平成 27年度

博士学位論文

Novel Utilization of Biomass for Activated Carbon Preparation and Catalytic Gasification

バイオマスを活用した新しい活性炭製造法及

びガス化法の開発

Boodsakorn Kongsomart (ブーサコン コンソムアート)

Novel Utilization of Biomass for Activated Carbon Preparation and Catalytic Gasification

バイオマスを活用した新しい活性炭製造法及

びガス化法の開発

by

Boodsakorn Kongsomart

A dissertation submitted to Graduate School of Engineering, Gunma University

For the Degree of Doctor of Engineering

Department of Environmental Engineering Science

Graduate School of Science and Technology

Gunma University

2016

Evaluation Committee

Professor Takayuki Ohshima, Chair

Faculty of Engineering, Gunma University, Japan

Professor Tomohide Watanabe, Vice-Chair

Faculty of Engineering, Gunma University, Japan

Professor Shinji Katsura, Vice-Chair

Faculty of Engineering, Gunma University, Japan

Associate Professor Reiji Noda, Vice-Chair

Faculty of Engineering, Gunma University, Japan

Professor Takayuki Takarada, Vice-Chair

Faculty of Engineering, Gunma University, Japan

I

Abstract

Biomass is an attractive material that much attention as renewable energy sources due to

their low-cost and environmental friendly. Biomass comprises organic compounds of carbons,

can reduce CO2 in the atmosphere by photosynthesis. Among various conversion

technologies, pyrolysis and gasification are one of the most attractive methods for biomass

utilization. In this research, the biomass ash as a catalyst prepared by combustion process for

the production of activation carbons (ACs) was investigated.

In Chapter 2 the effects of catalyst (chemical reagent and biomass) on specific surface

area and yield of activated carbon from biomass were investigated. CaCO3 and Ca(OH)2 are

catalysts in chemical activation. Chicken dropping compost is biomass as a catalyst to

compare the effect with chemical reagent. Activated carbon preparation was performed at

1000oC under N2 gas ambient. With increasing the amount of catalyst added, the specific

surface area was increased. The specific surface area of activated carbon reached the range

between 200 and 1100 m2g-1.

In Chapter 3, the preparation of the activated carbon (ACs) from teak sawdust (TS)

biomass mixed with chicken dropping compost ash (CCA) and empty fruit bunch ash

(EFBA) as activating agents were studied. The carbonization was done in pure N2 and

N2/CO2 stream gases by temperature range between 600 to 1000°C. The concentration of

CO2 in N2/CO2 gas was varied from 2 to 10%. The specific surface area (SSA) of TS mixed

with CCA (1:1 wt%) carbonized at 1000°C in N2 and N2/2%CO2 gas ambient was 930 and

1094 m2g-1, respectively. Larger SSA of carbonization in N2/2%CO2 gas ambient is due to

the reaction between CO2 gas and the carbon content in TS during pyrolysis. This can

II

increase pores and widen the pore size in ACs. Finally, the EFBA is more efficient in

increasing the SSA up to 30% compared to the CCA with the same process conditions.

In Chapter 4, the catalytic effects of two different biomass-derived ash catalysts, chicken

dropping compost ash (CCA) and empty fruit bunch ash (EFBA) on the performance of CO2

gasification of Loy Yang brown coal (LY) char were studied. The CO2 gasification was done

at temperatures between 650 to 800oC. It was found that the reaction rate was strongly

dependent on the temperature and the carbon conversion increases by increasing the CO2

gasification temperature. By using LY mixed with 10 wt% of EFB ash (EFBA), the maximum

char conversion of 1.0 with a high gasification rate was obtained when CO2 gasification was

carried out at 800oC for 30 min. Finally, the EFBA is more efficient in catalytic activity

compared to the CC ash (CCA) under the same conditions.

III

Table of contents

Abstract ..................................................................................................................................... I

Table of contents .................................................................................................................... III

Table of Figures ................................................................................................................... VIII

Table of Tables ...................................................................................................................... XI

Chapter 1. Introduction .......................................................................................................... 1

1.1 Current status of world energy consumption .............................................................. 1

1.2 Types of energy source ............................................................................................... 3

1.2.1 Fossil fuels ............................................................................................................. 3

1.2.2 Renewable energy .................................................................................................. 4

1.2.1.1 Biomass ...................................................................................................... 4

1.2.1.2 Geothermal energy ..................................................................................... 4

1.2.1.3 Hydroelectric power ................................................................................... 5

1.2.1.4 Wind energy ............................................................................................... 5

1.2.1.5 Solar energy ................................................................................................ 5

1.2.1.6 Solar thermal system .................................................................................. 5

1.3 World energy production ............................................................................................ 6

1.3.1 Oil ........................................................................................................................... 6

1.3.2 Coal ........................................................................................................................ 7

1.3.3 Natural gas .............................................................................................................. 8

IV

Table of contents (con't)

1.3.4 Biomass .................................................................................................................. 8

1.3.5 Nuclear ................................................................................................................... 8

1.4 Energy related issues ................................................................................................. 10

1.4.1 Global warming .................................................................................................... 10

1.4.2 Fossil fuel combustion .......................................................................................... 10

1.5 Technology development for power generation cost ................................................ 11

1.6 Biomass conversion technology ................................................................................ 12

1.7 Methods of biomass conversion ................................................................................ 14

1.7.1 Direct fired or conventional steam boiler ............................................................. 15

1.7.2 Co-firing ............................................................................................................... 16

1.7.3 Pyrolysis ............................................................................................................... 16

1.7.4 Gasification .......................................................................................................... 17

1.8 Description of the process ......................................................................................... 18

1.9 Pyrolysis process technology .................................................................................... 20

1.9.1 Slow pyrolysis ...................................................................................................... 20

1.9.2 Fast pyrolysis ........................................................................................................ 20

1.9.3 Flash pyrolysis ...................................................................................................... 21

1.10 Activated carbon ....................................................................................................... 22

1.10.1 Activation process .............................................................................................. 24

V

Table of contents (con't)

1.10.2 Carbonization ..................................................................................................... 24

1.10.3 Activation ........................................................................................................... 26

1.10.4 Applications of activated carbon from lignocellulosic biomass ........................ 27

1.10.4.1 Removal of SO2 ....................................................................................... 27

1.10.4.2 Removal of NO2 ....................................................................................... 29

1.11 Catalytic gasification ................................................................................................. 29

1.12 Interesting biomass used in this experiment ............................................................. 32

1.13 Relevant research ...................................................................................................... 33

1.14 Objective of this study ............................................................................................... 35

References ................................................................................................................................ 36

Chapter 2. Activated carbon from biomass using chemical reagents ............................... 42

2.1 Introduction ............................................................................................................... 42

2.2 Experimentals ............................................................................................................ 43

2.2.1 Materials ............................................................................................................... 43

2.2.2 Experimental set-up .............................................................................................. 44

2.2.3 Sample preparation ............................................................................................... 45

2.2.4 Characterization of the activated carbons ............................................................ 45

2.3 Results and discussion ............................................................................................... 45

2.4 Summary ................................................................................................................... 49

References ............................................................................................................................ 50

VI

Table of contents (con't)

Chapter 3. Preparation of activated carbons from teak sawdust using chicken dropping

compost and empty fruit bunch ............................................................................................ 52

3.1 Introduction ............................................................................................................... 52

3.2 Experimentals ............................................................................................................ 53

3.2.1 Raw materials ....................................................................................................... 53

3.2.2 Sample preparation ............................................................................................... 54

3.2.3 Characterization of the activated carbons ............................................................ 55

3.3 Results and discussion ............................................................................................... 55

3.3.1 Preparation of ACs from TS mixed with CCA activating agent .......................... 55

3.3.1.1 Effects of CCA activating agent ................................................................ 55

3.3.1.2 Effects of ash to biomass weight ratio ....................................................... 56

3.3.1.3 Effects of carbonization gas ambient using CCA activating agent ............ 58

3.3.1.4 Effects of carbonization temperature using CCA activating agent

on CO2 gas ................................................................................................. 59

3.3.1.5 Effects of CO2 concentration in carbonization process using CCA

activating agent .......................................................................................... 62

3.3.2 Comparison of CCA and EFBA activating agents ............................................... 63

3.4 Conclusions ............................................................................................................... 65

References ................................................................................................................................ 66

VII

Table of contents (con't)

Chapter 4. Catalytic effects of biomass on Loy Yang brown coal gasification ................ 70

4.1 Introduction ............................................................................................................... 70

4.2 Experimental ............................................................................................................. 72

4.2.1 Materials ............................................................................................................... 72

4.2.2 Catalytic gasification ............................................................................................ 73

4.3 Results and Discussion .............................................................................................. 73

4.3.1 Characteristic of biomass ash ............................................................................... 73

4.3.2 Effect of gasification temperature on LY char conversion .................................. 76

4.3.3 Effects of biomass ash contents ............................................................................ 76

4.3.4 Effect of biomass-derived ash type ...................................................................... 78

4.3.5 Comparison of chemical reagent with ash ........................................................... 81

4.4 Conclusions ............................................................................................................... 84

References ................................................................................................................................ 85

Chapter 5. Conclusions .......................................................................................................... 88

Acknowledgements ................................................................................................................ 90

Publication lists ...................................................................................................................... 92

Author biography .................................................................................................................. 94

VIII

Table of Figures

Figure 1-1. World energy consumption from 1908 to 2030. ..................................................... 2

Figure 1-2. Historical and forecast data on global oil production in 1859 to 2100. .................. 6

Figure 1-3. Historical and forecast data on global coal production in 1900 to 2100. ................ 7

Figure 1-4. Global coal reserves in 2012. .................................................................................. 7

Figure 1-5. World gas productions. ........................................................................................... 9

Figure 1-6. Development of global biomass use by main world regions from 1990 to 2010. .. 9

Figure 1-7. Global warming mechanism ................................................................................. 10

Figure 1-8. CO2 emission from fossil fuel combustion by section and fuel type in 2006. ...... 11

Figure 1-9. Learning curves for power generation technologies up to 2030. .......................... 12

Figure 1-10. Sources of biomass for conversion to energy. .................................................... 13

Figure 1-11. Renewable nature of biomass conversion into energy. ....................................... 13

Figure 1-12. Thermochemical processes for biomass conversion. .......................................... 15

Figure 1-13. Schematic reaction zones of wood pyrolysis ...................................................... 18

Figure 1-14. Reaction paths of biomass pyrolysis. .................................................................. 18

Figure 1-15 Pyrolysis process technology. .............................................................................. 21

Figure 2-1. Schematic diagram of pyrolysis process used in this experiment. ........................ 44

Figure 2-2. Specific surface area of biomass char after pyrolysis in N2 gas ambient at 1000°C.

.................................................................................................................................................. 46

Figure 2-3. Specific surface area of activated carbon obtained from different types of biomass

mixed with various types of catalyst at the ratio of 1.0. ....................................... 47

Figure 2-4. Specific surface area of activated carbon obtained from different types of biomass

mixed with various types of catalyst at the ratio of 3.0. ....................................... 48

IX

Table of Figures (con't)

Figure 2-5. Activated carbon yield of activated carbon obtained from different types of

biomass mixed with various types of catalyst at the ratio of 1.0. ......................... 48

Figure 2-6. Activated carbon yield of activated carbon obtained from different types of

biomass mixed with various types of catalyst at the ratio of 3.0. ......................... 49

Figure 3-1. Specific surface area of TS and TS mixed with CCA. .......................................... 56

Figure 3-2. Specific surface area and yield of ACs with different CCA to biomass weight

ratio. ...................................................................................................................... 57

Figure 3-3. Adsorption isotherm of ACs with different CCA to biomass weight ratio. .......... 58

Figure 3-4. Specific surface areas of the ACs from TS prepared in pure N2 and N2/2%CO2

gas ambient at the carbonization temperature of 1000oC. .................................... 59

Figure 3-5. Specific surface area and ACs yield obtained from carbonization process in

N2/2%CO2 gas ambient by varied the carbonization temperature from 600 to

1000oC. ................................................................................................................. 60

Figure 3-6. Pore size distribution obtained from carbonization process with N2/2%CO2 gas

ambient at different carbonization temperatures. ................................................. 61

Figure 3-7. Specific surface area and ACs yield with different CO2 concentration in N2/CO2

gas ambient at 600oC. ........................................................................................... 63

Figure 3-8. Specific surface area of ACs from TS mixed with CCA and EFBA by varied the

ash/biomass weight ratio from 0.6 to 1.0 and carbonized in different gas ambient

at 1000oC. ............................................................................................................. 64

Figure 3-9. Pore size distribution of ACs from TS mixed with CCA and EFBA with the

ash/biomass weight ratio of 1.0 and carbonized in N2 gas ambient at 1000oC. ... 65

X

Table of Figures (con't)

Figure 4-1. XRD patterns of EFBA. ........................................................................................ 75

Figure 4-2. XRD patterns of CCA. .......................................................................................... 75

Figure 4-3. CO2 gasification profiles of LY char. ................................................................... 77

Figure 4-4. CO2 gasification profiles of LY1 char at different EFBA contents of 2 to 10 wt%.

.............................................................................................................................. 77

Figure 4-5. CO2 gasification profiles of LY1 char (10 wt% of EFBA). .................................. 79

Figure 4-6. CO2 gasification profiles of LY2 char (10 wt% of CCA). .................................... 79

Figure 4-7. XRD patterns of LY1 char (10 wt% of EFBA) after CO2 gasification. ................ 80

Figure 4-8. XRD patterns of LY2 char (10 wt% of CCA) after CO2 gasification. .................. 80

Figure 4-9. Effect of gasification temperature on the conversion of LY char with and without

mixing with 10 wt% of EFBA and 10 wt% of CCA. ........................................... 81

Figure 4-10. Comparison of conversion of LY1 char (10 wt% of EFBA) and LY3 char of

(10 wt%) of K2CO3) at 700°C. ............................................................................. 82

Figure 4-11. Comparison of conversion of LY2 char (10 wt% of CCA) and LY4 char of

(10 wt%) CaCO3) at 700°C. ................................................................................. 82

Figure 4-12. XRD patterns of LY1 char (10 wt% of EFBA) and LY3 char

(10 wt% of K2CO3) after gasification at 700°C. .................................................. 83

Figure 4-13. XRD patterns of LY2 char (10 wt% of CCA) and LY4 char

(10 wt% of CaCO3) after gasification at 700°C. .................................................. 83

XI

Table of Tables

Table 1-1 Total ultimately recoverable conventional oil resources. .......................................... 6

Table 1-2 Formation of different products from various types of pyrolysis ............................ 22

Table 1-3 Type of pyrolysis in relation to operating processes and products with greater yield.

.............................................................................................................................. 22

Table 1-4 Ultimate and proximate analysis of lignocellulosic biomass used for air pollution

control. .................................................................................................................. 25

Table 1-5 Various activation conditions for preparation of lignocellulosic chars. .................. 27

Table 1-6 Preparation method and adsorption capacity of various activated carbons from

lignocellulosic biomass. ....................................................................................... 28

Table 1-7 Characteristics of activated carbon used for removal of SO2. ................................. 28

Table 1-8 The preparation conditions and characteristics of activated carbon for removal of

NO2. ...................................................................................................................... 29

Table 1-9 The most important char-gas reactions and its effective catalysts. ......................... 30

Table 2-1 Proximate and ultimate analysis of raw materials ................................................... 44

Table 3-1 Proximate and ultimate analysis of the teak sawdust .............................................. 54

Table 3-2 Composition of metal oxide in CCA and EFBA ..................................................... 55

Table 3-3 Parameters of the activated carbon obtained from the carbonization process ......... 60

Table 4-1 Proximate and ultimate analysis of the Loy Yang brown coal ................................ 73

Table 4-2 Elements of biomass ash ......................................................................................... 74

Chapter 1

Introduction

Energy is an essential physical substance to perform work for human being. The energy

is useful for the economic, technology, social, which can improve our quality life. The

various forms of energy such as heat, light, electrical, etc. are obtained from the conversion

of the fuel. The utilizing of energy, fuel has converted numerous times before it reaches to

the point-of-use such as household, factory, department store and automotive.

Typically, the energy source can be categorized into three groups (1) fossil fuel, (2)

nuclear-powered source and (3) renewable energy. The fossil fuels are in the form of coal,

petroleum, and natural gas. The nuclear-powered source can be produced by nuclear fission

or nuclear fusion reaction. In case of renewable energy sources, the energy can be converted

from solar, wind, hydroelectric, geothermal power and biomass. According to the

International Energy Agency (IEA), the global energy consumption has grown up doubled in

the past 50 years related to the increasing of the world population. It was predicted that 88%

of world energy will be consumed from the fossil fuels in 2030.

Not only the energy shortage which might occurs in the near future, the energy related

issues, especially the global warming should be considered. Therefore, the new methods to

produce energy, especially from renewable energy resource with sustainable and

environmental friendly, are developing.

1.1 Current status of world energy consumption

Nowadays, the main energy consumption is fossil fuels including oil, gas, and coal. The

fossil fuels consumption will reach 10 gigatons of oil equivalent (Gtoe) per year with 1.6 tons

of oil equivalent (toe) as energy consumption per occupant. According to IEA research, the

2

primary energy consumption has grown by 49% but the CO2 emission was also increased by

43% during past two decades (1984–2004) [1-3]. The average annual increasing of energy

consumption and CO2 emission was 2% and 1.8%, respectively. Moreover, the world energy

consumption is predicted to increase up to 70% in 2030 as the graph shown in Fig. 1-1. The

world gross inland consumption (GIC) shows that oil still represents the largest share of the

energy source (34%) in 2030.

It was predicted that the global energy that obtains from renewable sources including

hydropower, geothermal energy wind, solar and hydropower energy will reach 8% of total

world energy requirements in 2030. This prediction is lower than 13% of the energy utilizing

that observed in 2000 due to the continuous decline of biomass consumption in Asia and

Africa. However, the evolution of the share of renewables in total energy consumption in

Europe countries is highest progression among other industrialized regions.

Figure 1-1. World energy consumption from 1908 to 2030.

3

1.2 Types of energy source

In this section, the types of energy source including fossil fuels, renewable energies, and

nuclear-powered source will be briefly introduced.

1.2.1 . Fossil fuels [4-8]

The fossil fuels are the energy source that obtained from the remains of ancient plants and

animals, which accumulated in the geologic over hundreds of millions of years. Those

organic materials are acts like hydrocarbon-containing natural resources. After those natural

buried substances are reacting with the heat and pressure in the earth's crust, it can be

converted to the form of coal, crude oil, natural gases and heavy oils.

Coal is formed by the decomposing of remained plants by using high atmospheric

pressure and high temperature through the calcification process. Based on the different types

of the nature sources, more than 1,200 different compositions of coal are available.

The natural gas is one form of fossil fuels that commonly found at the inner layers of

earth or at the surface of the petroleum reservoirs. Among the natural gases, methane is the

environmental friendly compared to the other forms of fossil fuel that normally used for

household purpose.

Petroleum is transformed by the remains of oceanic plants and bacteria over million years.

This type of fossil fuel is consumed around 40% of the world demand of energy.

Crude petroleum is used to produce various types of distillate fuels such as kerosene, jet

fuel and so on. Moreover, the by-products of the petroleum distillation can be used in plastic

production.

Although the fossil fuels are useful energy resource, the utilizing of fossil fuels is one of

the largest sources to emit the carbon dioxide (CO2) to the atmosphere. The accumulation

layer of CO2 in the atmosphere can reflect the UV radiation to the ground and it also can trap

the heat, which is the root cause of greenhouse effects that contributes to global warming.

4

1.2.2 Renewable energy

The renewable energy is the clean energy that considering using instead of conventional

fossil fuels. The sources of renewable energy from natural are rain, sunlight, wind, waves,

tides, and geothermal heat. Typically, the renewable energy can be applied in four

applications; (1) electricity generation, (2) air and water heating/cooling, (3) rural energy

services, and (4) motor fuels. In this section, six types of renewable energy sources including

biomass, geothermal energy, hydroelectric power, wind energy, solar energy, and solar

thermal systems will be introduced.

1.2.1.1 Biomass [9-10]

Biomass is a carbon-based biological material that derived from plant-based materials,

which is a living or recently living organisms. Biomass is a substance that composed with a

mixture of organic molecules including hydrogen, oxygen, nitrogen, alkali, alkaline earth,

and heavy metals. The metal components in biomass are found in the form of functional

molecules called porphyries, which include chlorophyll that contains magnesium.

1.2.1.2 Geothermal energy [11-13]

Geothermal energy is an energy that release from the earth’s core. The high temperature

around 5000°C of the earth’s core can melt the outer layers of mantle and become magma.

When the rain water seeps down through the cracks of geological, it will react with

superheated of the magma or the hot rocks beneath. Then the rain water that suddenly heated

at the magma surface will vaporized and release back to the earth surface in the form of high

pressure vapor. An example of the utilizing of geothermal energy at the earth surface is hot

springs (or called geysers).

5

1.2.1.3 Hydroelectric power [14-15]

Hydroelectric power is the form of electricity that generated by the movement of water

stream on the hills and mountains that that eventually move down to the lower ground level

by gravity force. The movement of water pass through the turbine blades can generate

electricity. The cycling of rain fall and melting snow make the hydropower is the cheapest

and most clean fuel renewable source.

1.2.1.4 Wind energy [16]

Wind energy is generated by converting wind flow through the wind turbines. The wind

turbines convert the force of the wind to propel an electric generator to create electricity. The

multiple wind turbines can be installed on-shore (land) and off-shore (sea) to generate the

electricity grid.

1.2.1.5 Solar energy [17-18]

The solar energy is an energy source that can be used to produce electricity. The heat and

photons in the sunlight is reacts with the surface of semiconductor device called Photovoltaic

(PV) cell. The photons and sunlight energy is collected by the PV cell and convert to

electricity that can keep in the battery for further utilization.

1.2.1.6 Solar thermal system [19-20]

Solar thermal electric energy is the energy that utilizing the sunlight to heat up the fluid

or gas in the heat engine to rotating the motor. The heat engine such as steam engines and gas

turbines has efficiency around 30 to 40%, which can produce megawatts of power.

6

1.3 World energy production

1.3.1 Oil

The majority of oil production comes from different offshore area such as West

Siberia, Persian Gulf region, East Siberia, Caspian Sea, South America, and Gulf of Mexico.

Table 1-1 estimates that the average world conventional oil ultimately recoverable resources

(URR) is 510 Bt. Figure 1-2 shows that by the end of the 21st century, world cumulative oil

production will reach 4700 to 5000 Bt.

Table 1-1 Total ultimately recoverable conventional oil resources.

Indicator Bt %

Cumulative production 165 32

Reserves 162 32

Undiscovered resources 183 36

Ultimately recoverable oil resources 510 100

Figure 1-2. Historical and forecast data on global oil production in 1859 to 2100.

7

1.3.2 Coal

Figure 1-3 shows that the global coal production predicted by IPGG is around 10 to

12 Btpa in the year of 2030 to 2040. The limits to growth in global coal production are

related to the environmental restrictions and depletion of the coal resource base. However,

United States of America (USA) and Russia reserves coal more than 50% of the total world

coal reserves (395 Bt). Those countries plan to increase their coal production in the 21st

century. Figure 1-4 show that the world coal reserves (431 Bt) except USA and Russia, will

produce about 10 to 11 Bt by 2060. Therefore, many countries are increasing their

investments in exploration of high-grade coal resources. [21]

Figure 1-3. Historical and forecast data on global coal production in 1900 to 2100.

Figure 1-4. Global coal reserves in 2012.

8

1.3.3 Natural gas

Figure 1-5 show the increasing of the world gas production from 1975 to 2025. The

OECD region shows the increasing of gas production of 3% between 2000 and 2025. It was

predicted that OECD will produce more than 40% of the world’s total gas production in 2025.

However, the CIS region also produce one third of the gas production, which is almost

equally allocated to OECD. Moreover, ten largest gas producers across the different

continents will support more than 80% of the world’s total natural gas production in 2030. [22]

1.3.4 Biomass [23]

Figure 1-6 shows that OECD Europe has increased the global sharing of bioenergy

demand from 6 to 10%, while China decreased their sharing from 22 to 16%. Among the

different types of biomass, wood fuel such as pellets, fuel wood and charcoal, and biodiesel,

palm oil, bioethanol are the most widely used and commercial. The volume of trading the

wood products that used as energy has reached 1 EJ in 2011. This amount is equal to 2% of

the total use of biomass energy around the world. The wood pellets is the largest biomass

products that has been traded (130 PJ) in 2011. The mainly wood pellets are based on

sawdust and wood residues as feedstock. Moreover, the bioethanol which exported from

Brazil (48%), USA (6%), and France (6%) are more than half of the global market.

1.3.5 Nuclear [24]

In 2005, the 442 nuclear power plants in global with a total capacity around 370 GWe

produced 16% of the world total electricity power consumption (2626 TWh). Among the

worldwide, USA has the largest number of reactors while France using nuclear power as a

main source for electricity generation. It was predicted that the nuclear power plants in global

will have a capacity between 279 and 740 GWe in 2030.

9

In Japan, nuclear power is the main source for electrical generation. Therefore, more than

55 nuclear reactors are currently operated to produce 40% of total national electricity

consumption. However, the plans for construction of new reactors in Japan have been scaled

down due to the safety consideration after the disaster at Fukushima nuclear power plant. In

China, nine reactors are in operation and 40 new reactors will be installed to support a total

capacity of 41 to 46 GWe by 2020.

Figure 1-5. World gas productions.

Figure 1-6. Development of global biomass use by main world regions from 1990 to 2010.

10

1.4 Energy related issues

1.4.1 Global warming [25-26]

Global Warming is one of the most severe problems in global due to the increasing of

average surface temperature of the atmosphere. By burning the fossil fuels, various types of

gases such as carbon dioxide (CO2), carbon monoxide (CO), methane, nitrous oxide are

released to the atmosphere. It was found that increasing small amount of carbon dioxide

(CO2) in atmospheric can cause a substantial increase in the Earth’s surface temperature. The

mechanism of CO2 emissions from and trap heat to escape from Earth atmosphere are shown

in Fig. 1-7. As we know that the earth’s temperature is going to increase due to huge

consumption of fossil fuels in the next century. Therefore, the reduction of the emission of

CO2 to the atmosphere should be decreased to prevent the disaster from the greenhouse

effects.

1.4.2 Fossil fuel combustion

During the combustion of fossil fuels such as petroleum, natural gas, and coal to produce

energy, the carbon content such as CO2 that stored in fossil fuels is emitted to the atmosphere.

Figure 1-8 shows that the petroleum supplied the largest portion of domestic energy demands,

accounting of 47 % of total fossil-fuel-based energy consumption in 2006. In contrast, coal

and natural are taken account of 27 and 26 % of total fossil fuel consumption, respectively.

Figure 1-7. Global warming mechanism. [25]

Sunlight Sunlight

Earth Earth

Greenhouse gas

Greenhouse gas

Sea Sea Land Land

11

Figure 1-8. CO2 emission from fossil fuel combustion by section and fuel type in 2006 [27].

1.5 Technology development for power generation cost [28]

Besides the limits of natural sources of fuels that might be affects to its prices in the

future due to mismatch of demands and supply and the CO2 emission from the fuel

combustion process that generate the greenhouse effects, the development of alternative

energy technologies is required. The projection of technology development that is consistent

with historic trends is shown in Fig. 1-9.

To describe the enhanced technology performance, the conversion efficiency, total

investment cost and operation cost are changed. The hybrid approach is applied to the

technology development to estimate the amount of research that necessary to bring about

accelerated technological progress rather than the issue of higher R&D investments. This can

be used to determine the focusing technology policies to provoke technological development.

Note: Electricity generation also includes emissions of less than 0.5 Tg CO2 Eq. from

geothermal-based electricity generation.

12

Figure 1-9. Learning curves for power generation technologies up to 2030.

1.6 Biomass conversion technology

Biomass is the most abundant and renewable organic resources that comprises of all

biological materials. The biological waste (dead biomass) can be used for producing the

energy such as electricity and heat or used for an indirect source of energy such as fuels. The

living organisms or their components such as algae, microorganisms and enzymes can be

used to produce energy using biofuels cells. Figure 1-10 shows various sources of biomass

that can be used for biomass conversion into energy. In the total process of biomass

conversion to energy, including the purpose of energy generation and environmental cleanup

is accomplished.

Inve

stm

ent [

Euro

/kW

]

Cumulative installed capacity [MW]

13

Figure 1-10. Sources of biomass for conversion to energy.

Figure 1-11. Renewable nature of biomass conversion into energy.

The factor of timeframe is one important parameter that should be considered for the

renewable of the energy source. For example, the energy from the fossil fuels such as coal,

oil, and natural gas take million years to renew. Beyond the fossil fuels, sunlight is an

infinitely abundant renewable source of energy. Therefore, it is very interesting to reduce the

time frame that required to converted sunlight into usable energy.

14

Among those renewable energy sources, biomass such as plants and trees are

excellent sources. Those biomasses can be considered as perpetual capable utilizing

photosynthesis to continuously tapping the energy from sunlight and converting it into

carbon-rich compounds as the mechanism shown in Fig 1-11.

Figure 1-11 shows the carbon that released into the atmosphere from burning process

of biomass can returns to the biomass by photosynthesis. After that, it is converted into

carbon-rich compounds for reconversion into energy. The photosynthesis process can

produce carbon positive, which is the carbon neutral unlike fossil fuel. For example, the

remaining CO2 in the atmosphere from the burning process of fossil fuel increases the total

amount of CO2. However, the conventional sinks such as trees and soils cannot absorb large

amount of CO2 in the atmosphere.

Therefore, it is necessary to reduce the global CO2 emissions by using the effective

energy generation technologies, which generates carbon negative. Based on various

technologies, Bioenergy with carbon capture and storage (BECCS) method are expected to

obtain net negative carbon emissions in global. This carbon capture and storage (CCS)

technology can release of CO2 into the atmosphere and redirect it into geological storage area.

Beyond the BECCS and CCS technology, high solar efficiency cultivation is an alternative

method to achieve carbon negative.

1.7 Methods of biomass conversion [28-32]

The technologies of biomass conversion can be classified into primary and secondary

conversion technologies. The primary conversion technologies such as combustion,

gasification and pyrolysis are directly convert the biomass into heat or other convenient form

of energy carrier such as (1) gases (methane and hydrogen), (2) liquid fuels (methanol and

ethanol), and (3) solids (char). The secondary technologies convert these primary conversion

15

products into the desired form of energy product such as transportation fuel or electricity. The

different thermochemical conversion processes are given in Fig. 1-12.

Figure 1-12. Thermochemical processes for biomass conversion.

The thermochemical processes involve high temperature and high pressure processing

of biomass. The combustion process to generate heat and/or power such as direct fried

(conventional steam boiler) and co-firing is done by heating the biomass in the excess oxygen

ambient. Those techniques are accounting for over 97% of the world’s bioenergy production.

The other processes such as pyrolysis and gasification are the heating process in the presence

of controlled oxygen to produce liquid fuels, heat and power.

1.7.1 Direct fired or conventional steam boiler

The direct fired or conventional steam boiler is the technique to covert the woody

biomass to the energy. In a direct-fired system, biomass is feed into the bottom parts of the

boiler, which connected to the air supply. When the biomass feedstock is burned, the hot

16

combustion gases are generated and pass through a heat exchanger. In this step, the water is

boiled and become a high pressure water steam that can use to rotate the turbine to generate

the electricity by driving the electricity generator.

To improve the efficiency of the direct fried process, the starting biomass is dried and

the size is reduced by Pelletization process. The size of pelletized (briquetted) biomass that

was reduced by mechanical process can improve the handling and the combustion

characteristics of biomass. For much more efficiency, the heat generated by the exothermic

process of combustion to power the generator can also be used to regulate temperature of

buildings and plant.

1.7.2 Co-firing

Co-firing is the simplest method to convert the biomass to energy by burning two

different types of materials at the same time. For example, the mixing of woody (15 wt%)

with biomass such as willow and switch grass can reduce the materials cost. The advantages

of adding small portion of biomass in coal boiler is to decrease the nitrogen and sculpture

oxides, which causes the formation of various types of air pollutions such as smog, acid rain

and ozone. Moreover, small amount of CO2 is released into the atmospheres. Therefore, the

co-firing method is low cost, more efficiency, cleanly and sustainable renewable energy.

1.7.3 Pyrolysis

Pyrolysis is an attractive method overcome the solid biomass due to it can convert

solid biomass into a transportable and easily stored fuel. In pyrolysis, the residues biomass

from nature such as wood residuals, and biogases, is inserted to high temperatures vacuum

chamber in the absence of oxygen resulting the generation of pyrolysis oil (bio oil), chars, or

singes. The advantage of pyrolysis process is that ash or energy did not generated during

transformation. The types of biomass is significantly effects the efficiency of pyrolysis

17

method. For example, straw and other agro-residues are important as an energy sources.

However, straw has high ash content which causes problems in pyrolysis.

1.7.4 Gasification

Gasification is a high efficiency process that can convert biomass into combustible

gases. There are two kinds of gasification process called direct gasification and indirect

gasification. Direct gasification process uses the combustion of air or oxygen to generate heat

through exothermic reactions. Indirect gasification process can transfer heat to the reactor

from the outside. The burned gas by-products can produce the heat for industrial and house

and it can use for mechanical or electrical power purposes. The conversion efficiencies

obtained from gasification is between 60 to 90%. Moreover, the gas can also use to produce

synthetic fuels.

Biomass gasifies can be categorized to updraft and downdraft. In case of updraft unit,

biomass is fed from the top of the reactor and air is injected into the bottom of the fuel bed.

By this setting, the efficiency of updraft gasifies can increase up to 90%. However, the gas

must be cooled before usage in the internal combustion engines due to the formation of tars.

Therefore, updraft unit is normally used for direct heat applications. Among those

gasification processes, the fluidized bed technology has a higher throughput due to its

superior heat and mass transfer with good uniform temperatures that creates faster rate of

reaction. Furthermore, the fluidized bed technology has better fuel moisture utilization

compared to the others gasification techniques.

18

1.8 Description of the process [30, 32]

Thermochemical conversion of biomass such as pyrolysis, gasification and

combustion is the most promising technologies for energy production. In this section, the

details of pyrolysis process will be introduced. Pyrolysis is one of the thermochemical

conversion processes that decompose the organic materials at elevated temperature as the

schematic shown in Fig. 1-13. Note that the oxygen did not participate into the pyrolysis

process. When the temperature is below 400°C, the pyrolysis process is defined as

carbonization which can produce charcoal, liquid fuels (heavy and light oils) and fuel gas.

However, when the pyrolysis temperature increases to 1000°C, a complete gasification of

biomass has occurred.

Figure 1-13. Schematic reaction zones of wood pyrolysis [30]

Figure 1-14. Reaction paths of biomass pyrolysis.

19

Figure 1-14 shows the reaction paths of biomass pyrolysis. In this reaction, the solid

materials are transformed into liquid and gas fractions with low to medium calorific value.

The calorific value is combines with synthesis gas (CO, H2 and CH4) and other low

molecular weight hydrocarbons. The liquid fraction that contains water and organic

compounds with low to medium molecular weight is called Tar. A solid carbonaceous

portion is called Char. Therefore, the advantages of pyrolysis are the capability to use wide

variety of materials and it can produce lower emissions of nitrogen oxides and sulphur

compared with other technologies. Moreover, the energy recovery of pyrolysis process can

reaches up to 70%. [33]

Typically, the by-products that obtain from pyrolysis reaction can be classified into

three groups called (1) synthesis gas, (2) tar, and (3) char. The synthesis gas is compose of

primarily of hydrogen, carbon oxides (CO and CO2), and gaseous hydrocarbons such as

methane. The calorific value of synthesis is around 13 to 15 MJ/Nm3.

Second, tar is the liquid product in the form of condensable organic (bio-oil) that

obtain from pyrolysis. The oily liquid portion consists of two phases called aqueous phase

and non-aqueous phase. An aqueous phase is an organic compounds containing oxygen with

a low molecular weight. A non-aqueous phase is an insoluble organic compound with a high

molecular weight such as aromatic.

Char is a solid carbon residue with low ash content. The density of char is 150 to 300

kg/m3 and it has a relatively high PCI (30 MJ/kg). Typically, char is used as a fuel to power

the pyrolysis process. Char also can be used for drying the biomass before putting it into the

reactor. Char is stable and complex for handling and does not degrade biologically.

20

1.9 Pyrolysis process technology [32-35]

Bio-oil from pyrolysis process can be used instead of conventional fuel oil and diesel

for electricity generation equipment such as furnaces, boilers and turbines. The utilizing of

pyrolysis is shown in Fig. 1-15. Based on the process parameters (reaction temperature,

heating rate, residence time) and products, pyrolysis can be categorized into three groups; (1)

slow pyrolysis, (2) fast pyrolysis and (3) flash pyrolysis.

1.9.1 Slow pyrolysis

Slow pyrolysis is typically occurs at reaction temperature over 400°C with long

residence time of 4 to 8 mins. The heating rate of 1 to 5°C/sec is typically used to balance

and stabilize the reactions. By using this optimized condition, large amount of gaseous phase

of the products will be obtained because of the complete secondary reactions. When the

process temperature increased from 400°C to 700°C, the final char yields and liquid products

decreased due to increasing of volatiles from tar. The maximum value of liquid products can

be obtained at the temperature of 550°C. That means, slow pyrolysis is subjected to the

secondary reactions which generates small amount of liquid products but generates large

amount of gas products.

1.9.2 Fast pyrolysis

Fast pyrolysis is typically occurs at reaction temperature between 500 to 950°C with

very short residence time of 1 to 5 s. The heating rate of fast pyrolysis is 100 to 300°C/sec.

The purpose of short residence time is to reduce the formation of intermediate products and

also increase the yield of tar up to 80 wt% of dry biomass. When the residence time is too short

(< 1 s), an incomplete depolymerization of biomass has occurred. Moreover, the liquid product is

21

Figure 1-15. Pyrolysis process technology.

not homogeneous due to the contribution of instability of bio-oil. To produce a high heating rate,

the cool down pyrolysis vapors should be very rapidly to obtain more stable product. To produce a

high heating rate, smaller homogenous particles are necessary. The small homogeneous particles

are often pre-treated with mechanical grinders. The fast pyrolysis is very interesting technology

because the produced liquid fuel is more dense and easier to handle.

1.9.3 Flash pyrolysis

Flash pyrolysis is a pyrolysis with high heating rate more than 1000°C/s and short

residence times of 0.1 to 1 sec. solid and volatile components. When the temperature is

between 450 to 750°C, more than 80 wt% of liquid fraction can be achieved. When the

temperature is higher than 750°C, the gas production can reach 80 wt% of the weight of the

products by using high speed reaction. The flash pyrolysis process has less tar and the

calorific value of gas increases around 5 to 10%. Table 1-2 and Table 1-3 show the summary

of different types of pyrolysis.

22

Table 1-2 Formation of different products from various types of pyrolysis [35]

Technique Process conditions By products

Temperature (°C) Residence time (s) Liquid Gas Char

Slow pyrolysis 400 Very long 30% 35% 35%

Intermediate

pyrolysis 500 10 to 20s 50% 30% 20%

Fast pyrolysis 500 > 2s 75% 13% 12%

Table 1-3 Type of pyrolysis in relation to operating processes and products with greater yield.

Pyrolysis type Residence

time

Temperature

(°C) Heating rate Products

Carbonisation Days 400 to 500°C Very slow Char

Slow pyrolysis 4 to 8 min 400 to 700°C 1 to 5 °C/s Gas

Fast pyrolysis 1 to 5 sec 500 to 950°C 100 to 300 °C/s Tar

Fast-liquid

pyrolysis < 1s 450 to 750°C > 1000°C/s Tar

Fast-gas pyrolysis < 1s > 750°C > 1000°C/s Gas

1.10 Activated carbon [36-40]

Activated carbons (ACs) are carbon with highly microporous structure, high specific

surface areas (SSA) and good adsorption properties. ACs allows the gas/liquid access into

internal pore surface and high degree of surface reactivity. ACs is an attractive material use

in various applications such as wastewater treatment, harmful gases removal in the air and

solvent recovery and ground water improvement. Nowadays, the agricultural by-products

23

have proved to be promising raw materials for the production of ACs because of their

availability at a low-cost, renewable and environmental friendly.

Lignocellulosic biomass is one of abundant agricultural wastes to produce ACs that

used for water and air pollution treatment. The advantages of ACs from lignocellulosic

biomass over the ACs from fossil sources are less emission of CO2 due to its carbon-neutral

cycle in the conversion process, reduce the amount of abundantly agricultural wastes and low

cost. Generally, the main components of lignocellulosic biomass are comprises with cellulose,

hemicellulose and lignin. Among those components, lignin is identified as the useful

component for the adsorption process due to the rich carbon content in lignin. Note that the

worldwide production of lignin-based biomass is 40 to 50 million tons per year.

ACs with high adsorption capacity can be produced from numerous sources of

lignocellulosic biomass such as coconut shell, durian shell, hazelnut shell, rubber seed shell,

palm kernel shell, almond shell, cotton stalks, plum stones, rice husk, pistachio-nut shell,

walnut shell, wood, etc. Lignocellulosic ACs can be used for chemical processes, petroleum

refining, waste water treatment, air pollution treatment and volatile organic compounds

(VOC) adsorption. Moreover, ACs obtained from Lignocellulosic provides an effective way

for gas phase applications such as for purification, separation, deodorization, storage and

catalysis.

To produce the ACs, the carbonization or pyrolysis process is firstly requires to

converse the char from biomass. In this process step, moisture and volatile compounds are

removed from the biomass. After the char producing, ACs can be fabricated using three

different processes: physical activation, chemical activation and physiochemical activation.

Physical activation is related to the gas-activating agents such as steam and CO2. The

chemical activation involves the presence of chemical agents such as metal oxide, alkaline

24

metal and acid. After the activation process, ACs with high porosity, large surface area and

high pore volume can be obtained.

1.10.1 Activation process

In the present days, the carbonization of lignocellulosic biomass to produce ACs is

widely study. Typically, the carbonization was done at the temperature below 800oC in the

absence of oxygen ambient. After that, the activation process is required to increase the

surface area and pore volume of ACs. There are two different activation processes called

physical activation and chemical activation.

1.10.2 Carbonization

The carbonization process is a thermal decomposition process that can eliminate a

non-carbon species and thus enrich the carbon content in carbonaceous material. The initial

porosity of char that obtained from carbonization process is still comparatively low.

Therefore, the porosity of char in activation process should be further developed due to the

products of this process step are significantly effect on the final product.

Among the carbonization process parameters such as heating rate, nitrogen flow rate

and the residence time, the carbonization temperature is the most important parameter.

Normally, high carbonization temperatures in the range between 600 to 700oC can reduce the

yield of char but can increase the liquid and gases release rate. Higher temperature is

preferred to obtain high quality char due to an increasing of amount of ash and fixed carbon

content with lower amount of volatile matter. Unfortunately, high carbonization temperature

can also decrease the yield due to the reduction of primary decomposition of biomass, the

decreasing of residence times of primary vapors inside the cracked particle and secondary

decomposition of char residue at high temperature. Moreover, high carbonization

25

temperatures also increase ash and fixed carbon content due to the decreasing of volatile

matter.

Char with a high fixed carbon content is requires for producing ACs. Low

volatilization with a high char yield can be obtained by using low carbonization heating rates

of 10 to 15oC/min. The low heating rate increases the dehydration and improves the

stabilization of the polymeric components [2-3]. However, the microporosity of char is

independent to the precursor composition and the carbonization heating rate. Table 1-4 shows

the proximate and ultimate analysis of several lignocellulosic biomass materials. It was found

that the carbonization is an important process to develop the initial pore structure in the char.

This can be explained by the release of volatile compounds from the carbon’s matrix.

Regarding to the pore development in the char has a great influence on the pore

characteristics of subsequently ACs production, the carbonization parameters should be taken

into account prior to activation process.

Table 1-4 Ultimate and proximate analysis of lignocellulosic biomass used for air pollution

control.

26

1.10.3 Activation

The activation process is use to increase the pore volume by increase the diameter of

pores, and thus increasing the porosity of ACs. ACs can be performed by three different

methods: physical activation, chemical activation and physiochemical activation (a

combination of physical and chemical activation). Physical activation use steam or CO2 while

the chemical activation uses various chemicals. The preparation of ACs from lignocellulosic

precursors by using various activation conditions is shown in Table 1-5. In the activation

process, unorganized carbon is removed during the first stage. Hence, the exposing of lignin

to the activating agents can lead to the development of micro-porous structure. In the second

stage of the reaction, the existing pores are widened and large size pores are formed. The

walls between the pores are simultaneously burnt-off. Completely burnt-off the wall of the

pores can increases the transitional pores and macro-porosity but also decreases the volume

of micro-pores. Therefore, the extension of burn-off carbon material is an important

parameter in activated carbon production.

During activation, the temperature is typically set between 800 to 1000oC to increase

the porosity and surface area of lignocellulosic carbon. In the physical activation, steam is

more effective than CO2 due to the smaller molecule of water can diffuse within the porous

of char faster than CO2 molecule. Therefore, steam activation is two or three times faster than

CO2 at the same conversion process. By using the steam, ACs with a relatively high surface

area compared to CO2 can be produced.

In the chemical activation, various chemical agents such as ZnCl2, H3PO4, KOH and

NaOH are used to develop the porosity. Generally, the chemical activation is takes place at

the temperature of 300 to 500oC, which is lower temperature than physical activation. The

dehydration and degradation mechanism of chemical agents can improves the development of

pore in carbon structure by using shorter treatment duration compared to physical activation.

27

Table 1-5 Various activation conditions for preparation of lignocellulosic chars.

In addition, the chemical activation process can form the ACs with larger surface area

with smaller ranges of micro-porosity compared to physical activation process. Furthermore,

the carbon yield of chemical activation is higher than that of physical activation.

1.10.4 Applications of activated carbon from lignocellulosic biomass

The rapid development in industrial activities that follows the growth of the world

population severely degraded the air quality due to high amount of pollutant emissions to

atmosphere. Therefore, air pollution control is a crucial step to achieve a sustainable energy

development. Currently, scrubbing gaseous pollutants using the adsorption method by

adsorbents such as ACs is widely used due to it has a suitable pore size in the micropore

region (< 2 nm) for gas adsorption and it has a large surface area for rapid reaction. A

summary of gaseous pollutants removal by various lignocellulosic ACs such as SO2, NOx,

H2S, volatile organic compounds (VOCs) and CO2 is presented in Table 1-6.

1.10.4.1 Removal of SO2

SO2 is the main precursors for acid rain generation, which is the most serious global

environment problem. The utilizing of ACs for SO2 adsorption through physical adsorption

and chemical adsorption takes a several advantages compared to the earlier methods. The

28

utilizing of metal oxides components in ACs that impregnated with the chemicals method to

remove SO2 from coal and oil combustion exhaust has been studied.

Table 1-6 Preparation method and adsorption capacity of various activated carbons from

lignocellulosic biomass.

Table 1-7 Characteristics of activated carbon used for removal of SO2.

29

1.10.4.2 Removal of NO2

The ACs with high porous structure that obtained from Lignocellulosic biomass is

widely used for minimizing the emission of NO2 gas. In addition, the surface chemistry that

defines by the type, number and chemical arrangement of heteroatoms on their surface are

considering. The dry adsorption process has better adsorption capacity compared to other

method due to the reaction mechanism is significantly changed and difficult to control in the

water. The micropores of activated carbon produced under optimum condition contributed up

to 96% of total pore volume. Preparation conditions and characteristics of activated carbon

for removal of NO2 are summarized in Table 1-8.

1.11 Catalytic gasification [41]

The gasification reaction is the important parameter to the catalytic or inhibiting

effects of the mineral matter in coals and chars. It is well known that a number of inorganic

elements present in coal/char have potential effects on the rates of gasification reaction on the

coal/char surface and in the gas phase. The reactions in the gas phase are contributed to ash

particles, whereas the reaction on or inside the reacting coal/char particles are contributed by

the dispersed minerals in the coal/char body. Generally, the alkali, alkaline earth, and

transition metals are the most effective catalysts for char-gas reactions as shown in Table 1-9.

Table 1-8 The preparation conditions and characteristics of activated carbon for removal of NO2.

30

Table 1-9 The most important char-gas reactions and its effective catalysts.

Reaction Effective catalysts

Char-oxygen Fe, Co, Ni

Char-steam K, Na, Ni

Char-carbon dioxide K, Na, Li, Ni, Co, Fe, Ca

Char-hydrogen K, Ni

When a catalytic effect is significant, the rate expression is depends on the presence

or absence of catalysts. To isolate such effects, kv and ks is determined by Eq. 1-1:

kv = Zvkvt and ks = Zskst (1-1)

Where kv and kst are the true rate constants of a reaction, and Zv and Zs represent the

effect of catalysis. The correct values of true rate constants are extremely difficult to

determine. However, the presence of a trace of solid or gaseous impurity is a significant

effect on the measured rate. Therefore, the rate expression shows in Eq. 1 is useful. As we

know that catalysts or impurities effects on the pre-exponential factor, kv0, and also the

activation energy, E, of carbon-gas reactions. Therefore, the values of E in carbon-CO2 and

carbon-O2 reaction systems have decreased due to the presence of catalytic minerals in coal.

The catalytic effects on the values of Zv and Zs for a given catalytic mineral are

depend on four factors; (1) The chemical form of the catalyst, (2) The physical form of the

catalyst, (3) The amount of catalyst, and (4) The temperature of reaction.

Thus Fe, Co, and Ni is effective catalysts in their elemental states or when they are

transformed to the elemental states during reaction. However, Potassium (K) and sodium

(Na) is the most effective in the form of carbonates and least effective as phosphates. Among

31

the oxides of iron and other transition metals, the stoichiometry of deficient oxides is better

catalyzes in C-CO2 and C-H2O reactions. This means, FeO or Fe3O4 is a better catalyst than

Fe2O3 in the same reactions.

Among the salts of those metals, the organic salts like oxalates, acetates, and citrates

show superior catalytic effects than those of the inorganic salts. This is because the former

group of salts yields finer subdivision and dispersion of the metal ions inside the body of the

reacting solid particles. The catalytic activity can be decreased by increasing the size of the

dispersed catalyst particles. The activity increases with an increase in the amount of catalyst

(or impurity) and then reaches the saturation point. However, larger amount of catalyst is not

an appreciable effect.

It was reported that the reduction of agglomerating tendency of caking coals can be

obtained by treatment of coals with Na2CO3 and/or K2CO3 (15 wt%) solutions at 700oC. It

was found that the rate of gasification is proportional to the concentration of the impregnated

potassium. It was also demonstrates that the agglomeration of coal can prevent by

impregnation of CaO into coal before gasification process due to the increasing of coal/char

reactivity and hydrocarbon yields in the gasifier.

It is believed that impurities decrease the CO/CO2 ratio in the C-O2 reaction, because

the impurities catalyze the secondary CO à CO2 reaction, without significantly affecting the

primary reaction, C à CO. This is because the CO and H2 are inhibitors of C-CO2 and C-

H2O reactions. However, this reaction is true only for un-catalyzed reactions. If the reactions

are catalyzed by oxides of Ni, Co, or Fe, then the CO, and H2 may act as promoters.

Therefore, the promoters might reduce the oxides of Ni, Co, and Fe. Moreover, if the process

temperatures are suitable, they can be changed to metallic states, which are the most effective

catalysts for gasification reactions. By using the same mechanism, steam may also act as a

promoter for these reactions, since it produces H2 and CO with carbon or char.

32

1.12 Interesting biomass used in this experiment [42-44]

In this experiment, three types of biomass including Chicken dropping compost (CC)

from Japan, Empty fruit bunch (EFB) from Malaysia and teak sawdust (TS) from Thailand

were studied. The EFB from Malaysia is the interesting biomass due to the large amount of

oil palm biomass about 30 million tons is produced each year. The remained agricultural

waste from the oil palm industry that can be used as renewable biomass is approximately

17.08 million tons a year. The EFBs with a relatively wet material (moisture content about 65

to 70 wt%) constitute 9% of the total oil palm industry.

In case of Teak sawdust (TS), it is the biomass that obtained from Thailand. In

Thailand, around 350 to 700 million tons of TS were produced a year. This material is very

attractive for carbon source. The chicken dropping compost (CC) from Japan is also

interesting materials due to it can produce up to 13 million tons per year. However, the

utilizing of CC is not suitable due to the pollution of air, soil, and ground water. The

summarized data of those interesting materials are shown in Fig. 1-16.

Figure 1-16. Interesting biomass used in this experiment.

Teak sawdust (Thailand)

(c)

Empty fruit bunch (Malaysia)

(a) (b)

Chicken dropping compost (Japan)

33

1.13 Relevant research

Garcia et. al. [45] studied low cost activated carbons with high surface area by

chemical activation using KOH at 700oC from the bamboo and residues from shells of the

fruits. The high porosity with surface areas ranging from 850 to 1100 m2/g was obtained. The

average pore width centered in the super micro-pores in the range of 1.3 to 1.8 nm. The

electrochemical performance of the activated carbons shows specific capacitance values at

low current density (1 mA/cm2) as high as 161 F/g in the shell of fruit activated carbon. This

is due to the presence of pseudo capacitance derived from surface oxygenated acidic groups

identified in this activated carbon.

Okman et.al. [46] studied the effects of activation reagents, reagent concentrations

and carbonization temperatures. It was found that lowest ACs yields were obtained at 800oC

for both K2CO3 (100 wt%) and KOH (100 wt%) reagents. By using the temperature of 800oC,

By using K2CO3 (50 wt%) and KOH (25wt%), microporous ACs with the highest specific

surface area of 1238 and 1222 m2g-1 were obtained at 800oC.

Sudaryanto et.al. [47] reported by using the cassava peel with KOH activation reagent

at the carbonization temperature of 750oC, the maximum specific surface area of 1600 m2/g

with pore volumn of 0.7 cm3/g were obtain at impregnation ratio of 5:2.

Lua et.al. [48] studied on the preparation and characterisation of effective adsorbents

from pistachio-nut shells. The optimum pyrolysis conditions was obtained at the temperature

of 500oC/2 hrs with a heating rate of 10oC/min. Under this pyrolysis condition, ACs with a

maximum BET surface area of 778 m2/g were obtained.

Kim et.al. [49] also studied the effects of the pyrolysis ambient including N2/CO2

without cooling, N2/CO2 with cooling and direct CO2 on the specific surface area of ACs. It

was reported that surface areas of biochars obtained by intermediate pyrolysis at 500 and

800oC were 107 and 249 m2/g, respectively. The maximum surface area of microporous ACs

34

(≤ 1 nm) of 1126 m2/g was obtained by carried out the process in N2/CO2 gas ambient without

cooling method at a final activation temperature of 900oC/1 hour.

Zhou et.al. [50] studied the effects of Na2CO3 catalyst on coal pyrolysis and

gasification of bituminous char. It was found that the activation energy of catalytic coal

gasification using Na2CO3 (10 wt.%) is 31.5 kJ.mol-1, which is less than that of non-catalytic

coal gasification. Therefore, Na2CO3 can improve the kinetics of coal gasification with CO2.

Kopyscinski et.al. [51] investigated the interactions of K2CO3 with ash-free brown

coal in N2 or CO2 atmospheres at 700 °C. The X-ray diffraction (XRD) analysis confirmed

that the evaporation of potassium is negligible because the K2CO3 does not exist in N2 and

CO2 atmospheres at 700°C. It was found that the CO2 gasification rate can be increased by

holding the ash-free coal mixed with K2CO3 in N2 prior to switching to the reaction gas. This

means, the catalyst reduction is necessary for a fast char conversion.

Perander et.al. [52] studied the catalytic gasification of Ca and K. It was found that

the gasification rate of the char linearly increased with an increasing of the concentration of

Ca or K. The catalytic activity of Ca was higher than K at the beginning of char gasification.

However, the catalytic effect of Ca decreased earlier than the catalytic effect of K. This might

related to the formation of CaCO3 and K2CO3 layer on the char surface.

35

1.14 Objective of this study

The conversion of biomass and coal as a renewable energy sources on the

thermochemical process to produce energy and fuels is considered. The conversion process

with low temperature, less pollution, and fewer effects to the global-warming issues

compared to existing fossil fuel is required.

The preparation of activated carbons (ACs) from agricultural by-products has attracted

much attention due to their low-cost, renewable and environmental friendly. Low temperature

coal gasification by metal species has been also studied in order to develop the coal

utilization with high efficiency. Many extensive works had been performed to investigate the

catalysts such as alkali and alkaline earth metals (AAEMs). However, the cost of purchasing

chemical catalysts is expensive. Therefore, it is necessary to identify inexpensive biomass as

a catalyst that will improve the surface area of ACs and reactivity of gasification.

The objective of this research is to study the novel utilization of biomass-derived ash for

ACs preparation and catalytic gasification. Two types of biomass-derived ashes including

chicken dropping compost ash (CCA) and empty fruit bunch ash (EFBA) was used as a

catalyst.

In ACs preparation, five different types of biomass that are abundant in Asia including

teak sawdust (TS), bagasse (BG), cypress (CP), palm kernel shell (PKS) and empty fruit

bunch (EFB) were used as a feedstock for pyrolysis to produce activated carbon. The specific

surface area of ACs that using CCA and EFBA was also compared with the process that

utilizing chemical reagents (CaCO3 and Ca(OH)2).

Moreover, the utilizing of different sources of catalyst on Loy Yang brown coal (LY)

char by CO2 gasification including CCA and EFBA biomass-derived ashes and K2CO3 and

CaCO3 chemical reagents were compared. Furthermore, various process parameters included

char conversion, reaction rate, gasification temperature were investigated.

36

References

[1]. Kwong Qi Jie, Ali Yusoff. A review of energy efficiency potentials in tropical buildings-

perspective of enclosed common areas. Renew Sustain Energy Rev 2011; 15: 4548-4553.

[2]. Lombard L,Ortiz J, Pout C. A review on building energy consumption information. J

Energy Build. 2008; 40: 394–8.

[3]. Payam Nejat, Fatemeh Jomehzadeh, Mohammad Mahdi Taheri, Mohammad Gohari,

Majid Muhd Zaimi Abd. A global review of energy consumption, CO2 emissions and

policy in the residential sector (with an overview of the top ten CO2 emitting countries).

Renew Sustain Energy Rev. 2015; 43: 843–62.

[4]. U.S. Census Bureau (2008) International data base, World population trends.

http://www.census.gov/gov/ipc/www/idb/worldpopgraph.html.

[5]. BP p.l.c., BP Statistical Review of World Energy, London, United Kingdom, June 2010.

[6]. Energy Information Administration, Washington, D. C., United State 2010.

[7]. Hossein Akbarzadeh , Richard J. Chalaturnyk. Structural changes in coal at elevated

temperature pertinent to underground coal gasification: A review. International Journal

of Coal Geology. 2014; 131: 126–146.

[8]. Malin Song, Jie Zhang, Shuhong Wang. Review of the network environmental

efficiencies of listed petroleum enterprises in China. Renewable and Sustainable Energy

Reviews. 2015; 43: 65–71.

[9]. L.J.R. Nunes, J.C.O. Matias, J.P.S. Catalão. Biomass combustion systems: A review on

the physical and chemical properties of the ashes. Renewable and Sustainable Energy

Reviews. 2016; 53: 235–242.

[10]. Sadegh Papari , Kelly Hawboldt. A review on the pyrolysis of woody biomass to bio-

oil: Focus on kinetic models. Renewable and Sustainable Energy Reviews. 2015; 52:

1580–1595.

37

[11]. Alexandre Rivera Diaz, Eylem Kaya, Sadiq J. Zarrouk. Reinjection in geothermal fields

- A worldwide review update. Renewable and Sustainable Energy Reviews. 2016; 53:

105–162.

[12]. Nasruddin, M. Idrus Alhamid, Yunus Daud, Arief Surachman, Agus Sugiyono, H.B.

Aditya, T.M.I. Mahlia. Potential of geothermal energy for electricity generation in

Indonesia: A review. Renewable and Sustainable Energy Reviews. 2016; 53: 733–740.

[13]. Jialing Zhu, Kaiyong Hu, Xinli Lu, Xiaoxue Huang, Ketao Liu, Xiujie Wu. A review of

geothermal energy resources, development, and applications in China: Current status and

prospects. Energy. 2015; 93: 466-483.

[14]. Seth Sheldon, Saeed Hadian, Ory Zik. Beyond carbon: Quantifying environmental

externalities as energy for hydroelectric and nuclear power. Energy. 2015; 84: 36-44.

[15]. A.F. Ribeiroa, M.C.M. Guedesb, G.V. Smirnovc, S. Vilela. On the optimal control of a

cascade of hydro-electric power stations: Review. Electric Power Systems Research.

2012; 88: 121–129.

[16]. Chong Wei Zheng, Chong Yin Li, Jing Pan, Ming Yang Liu, Lin Lin Xia. An overview

of global ocean wind energy resource evaluations. Renewable and Sustainable Energy

Reviews. 2016; 53: 1240-1251.

[17]. S.S. Chandel, M. Nagaraju Naik, Rahul Chandel. Review of solar photovoltaic water

pumping system technology for irrigation and community drinking water supplies.

Renewable and Sustainable Energy Reviews. 2015; 49: 1084-1099.

[18]. Alessandra Scognamiglio. Photovoltaic landscapes: Design and assessment. A critical

review for a new transdisciplinary design vision. Renewable and Sustainable Energy

Reviews. 2016; 55: 629-661.

[19]. S. Sadhishkumar, T. Balusamy. Performance improvement in solar water heating

systems- A review. Renewable and Sustainable Energy Reviews. 2014; 37: 191-198.

38

[20]. E. Halawa, K.C. Chang, M. Yoshinaga. Thermal performance evaluation of solar water

heating systems in Australia, Taiwan and Japan - A comparative review. Renewable

Energy. 2015; 3: 1279-1286.

[21]. A.E. Kontorovich, M.I. Epov, L.V. Eder. Long-term and medium-term scenarios and

factors in world energy perspectives for the 21st century. Russian Geology and

Geophysics. 2014; 55: 534-543.

[22]. World energy, technology and climate policy outlook.

https://ec.europa.eu/research/energy/pdf/weto_final_report.pdf

[23]. Global Bioenergy, Supply and demand projections, A working paper for Remap 2030.

https://www.irena.org/remap/IRENA_REmap_2030_Biomass_paper_2014.pdf

[24]. Aksel Sundstrom, Aaron M. McCright. Women and nuclear energy: Examining the

gender divide in opposition to nuclear power among swedish citizens and politicians.

Energy Research & Social Science. 2016; 11: 29-39.

[25]. Global greenhouse warming. http://www.global-greenhouse-warming.com/what-is-

global-warming.html

[26]. Global Warming FAQ.

http://www.nmsea.org/Curriculum/Primer/Global_Warming/fossil_fuels_and_global_wa

rming.htm

[27]. International Energy Agency, CO2 Emissions from Fuel Combustion, Paris, France,

2010.

[28]. Energy and Climateand Change.

https://www.iea.org/publications/freepublications/publication/WEO2015SpecialReporto

nEnergyandClimateChange.pdf

[29]. Carl W. Hall. Biomass as an alternative fuel. Government Institute. pp. 77-96.

39

[30]. Overend, R. P. Themochemical conversion of biomass. Renewable energy sources

charged with energy from the sun and originated from earth-moon interaction, volume 1,

2009.

[31]. The ministry of agriculture, forestry, and fisheries. The Asian biomass handbook; a

guide for biomass production and utilization, Japan, 2008.

[32]. Sanjay P Mande, F. Themochemical conversion of biomass: Renewable energy

engineering and technology, 2007, 705-728.

[33]. Luka, Z. A Master’s thesis done at RES, the school for renewable energy science in

affiliation with university of Iceland and university of akureyri, February 2009.

[34]. Fortuna, F. J. Anal. Appl. Pyrol. 1997, 403-417.

[35]. IEA Bioenergy: pyrolysis http://www.pyne.co.uk/Applications

[36]. K. Sato, et. al., “A simple fabrication route of activated carbon from chicken dropping”,

Journal of Analytical and Applied Pyrolysis, 101, 86-89 (2013).

[37]. J. Przepiroski, et. al., “Porous carbon material containing CaO for acidic gas capture:

Preparation and properties”, Journal of Hazardous Materials, 263, 353-360 (2013).

[38]. I. Okman, et. al., “Activated carbons from grape seeds by chemical activation with

potassium carbonate and potassium hydroxide”, Applied Surface Science, 293, 138-142

(2014).

[39]. J. Matos, et. al., “Synthesis and characterization of activated carbon from sawdust of

algarroba wood. 1. Physical activation and pyrolysis”, Journal of Hazardous Materials,

196, 360-369 (2011).

[40]. Norhusna Mohamad Nor, Lau Lee Chung, Lee Keat Teong, Abdul Rahman Mohamed.

Synthesis of activated carbon from lignocellulosic biomass and its applications in air

pollution control - a review. Journal of Environmental Chemical Engineering. 2013; 1:

658–666.

40

[41]. John Rezaiyan, Nicholas P. Cheremisinoff. Gasification technologies, A prime for

engineers and scientists. Taylor and Francis. 35-86.

[42] Joseph, L. M. H., “A case study on palm empty fruit bunch as energy feedstock,” SEGi

review, Vol. 3, No. 2, pp. 3-15 (2010).

[43] H. Suzuki, and T. Yoshida, “Current situation and concerns with woody biomass use in

ASEAN countries,” JARQ, Vol. 43, NO. 1, pp. 37-43 (2009).

[44] B. Joseph, et. al., “Sustainable energy resources from chicken,” Asian J. of Appl. Sci., 4:

pp. 355-361 (2011).

[45]. P. Gonzaalez-Garciiaa, T.A. Centeno, E. Urones-Garrote, D. Avila-Brande, L.C. Otero-

Diiaz. Microstructure and surface properties of lignocellulosic-based activated carbons.

Applied Surface Science. 2013; 265: 731–737.

[46]. Irem Okman, Selhan Karagooz, Turgay Tay, Murat Erdem. Activated carbons from

grape seeds by chemical activation with potassium carbonate and potassium hydroxide.

Applied Surface Science. 2014; 293: 138-142.

[47]. Y. Sudaryanto, S.B. Hartono, W. Irawaty, H. Hindarso, S. Ismadji. High surface area

activated carbon prepared from cassava peel by chemical activation. Bioresource

Technology. 2006; 97: 734–739.

[48]. Aik Chong Lua, Ting Yang, Jia Guo. Effects of pyrolysis conditions on the properties of

activated carbons prepared from pistachio-nut shells. J. Anal. Appl. Pyrolysis. 2004; 72:

279–287.

[49]. Su-Hwa Jung, Joo-Sik Kim. Production of biochars by intermediate pyrolysis and

activated carbons from oak by three activation methods using CO2. Journal of

Analytical and Applied Pyrolysis. 2014; 107: 116-122.

[50]. Lu Ding, Zhijie Zhou, Qinghua Guo, Wei Huo, Guangsuo Yu. Catalytic effects of

Na2CO3 additive on coal pyrolysis and gasification. Fuel.2015; 142: 134-144.

41

[51]. Jan Kopyscinski, Moshfiqur Rahman, Rajender Gupta, Charles A. Mims, Josephine M.

Hill. K2CO3 catalyzed CO2 gasification of ash-free coal. Interactions of the catalyst with

carbon in N2 and CO2 atmosphere. Fuel. 2014; 117: 1181–1189.

[52]. M. Perander, N. DeMartini, A. Brink, J. Kramb, O. Karlstroom, J. Hemming, A.

Moilanen, J. Konttinen, M. Hupa. Catalytic effect of Ca and K on CO2 gasification of

spruce wood char. Fuel. 2015; 150: 464-472.

Chapter 2

Activated carbon from biomass using chemical reagents

2.1 Introduction

Biomass is an organic matter on earth that obtained from plant and animal growth in the

form of plant residues and organic wastes from animal and human. The variety of biomass is

depends on both seasonally and geographically across the world. Biomass can be prepared by

harvest, collect, assemble, compress, transport, and then stored for further use. The estimates of

the biomass weight that the approximate annual worldwide fixation of carbon from all sources is

around 200x109 tons. The utilizing of biomass from agricultural wastes is to convert it into

activated carbon (ACs).

ACs is the form of carbon with small and low-volume porosity in micro-pores and meso-

pores, which typically used as adsorbent materials due to its high surface area. ACs can produce

from different residual biomass utilizing physical or chemical activation processes and used in a

various applications such as separation and purification technologies.

The preparation of ACs from agricultural by-products with low-cost is considering in the

view of economic and environmental impacts. First, low-cost agricultural waste such as residual

biomass with low ash and high volatile content has converted to be useful and valuable

carbonaceous adsorbents. The preparation of ACs from lignocellulosic biomass can be obtained

by three factors; (1) the porosities and surface of the biomass to produce adsorbent, (2) the low

cost and the possibility for mass production, and (3) the waste disposal problem with the

addition of value added products.

Activated carbons can be produced by the conventional partial gasification of the char

either with steam, CO2 or a combination of steam and CO2. Generally, the physical activation

that comprises with two-step process including the carbonization of a carbonaceous material and

the activation of char at elevated temperature. The activation process is typically carried out in

43

the oxidizing gases ambient such as steam, CO2 or a combination of steam and CO2. The

gasification reaction can remove the carbon atoms and produce a wide range of predominantly

micro-pores that can produce a porous ACs.

In case of chemical activation process, the carbonization was done at in a single step. The

precursors are mixed with dehydrating chemicals such as H3PO4, ZnCl2, K2CO3, NaOH or KOH.

The advantages of chemical activation are included the single step activation with low activation

temperatures and short activation time. The chemical activation process has higher yields and

better porous structure compared to physical activation process. Moreover, the chemical agents

in the chemical activation process did not form tar and it also can reduce the production of other

volatile products. The main disadvantage of chemical activation process is the washing step.

This washing step is time consuming due to the necessary of completely remove the activation

agent from the carbon.

2.2 Experimental

2.2.1 Materials

Carbon source in this section has five types of biomasses including teak sawdust (TS)

from Thailand, cypress (CP) from Japan, bagasse (BG), empty fruity bunch (EFB), and palm

kernel shell (PKS) from Malaysia. The particle size of TS is between 0.25 to 0.50 mm while the

particle size of other materials is between 0.5 to 1.0 mm.

The proximate and ultimate analyses of the initial material are shown in Table 2-1. The

volatile matter and ash content were measured by a thermo gravimetric analyzer (TGA 701,

Leco Co., Ltd.). The content of C, H, N and O elements were determined using an elemental

analyzer (TruSpec CHN, version 100, Leco Co., Ltd) and the content of sulfur element was

44

Table 2-1 Proximate and ultimate analysis of raw materials

Sample Proximate analysis Ultimate analysis

Volatile

matter

Ash Fixed

carbon

C H N O

(diff)

TS 76.8 0.8 2.4 49.8 3.8 1.8 44.6

CP 79.0 0.4 20.6 47.1 8.9 0.4 43.6

BG 83.4 2.5 14.1 46.2 5.6 0.4 47.8

PKS 74.6 1.2 24.2 52.0 5.0 0.4 42.6

EFB 80.6 2.7 16.7 45.3 5.5 0.5 48.7

analyzed by sulfur analyzer (Leco SC-432, Leco Co., Ltd). Five types of biomasses used in this

experiment were dried at 107oC for 1 hour before mixed with catalyst. Biomass is chicken

dropping compost (CC). Chemical reagent including calcium hydroxide (Ca(OH)2) and calcium

carbonate (CaCO3) and were used as a catalyst. It was dried at 107oC for 1 hour before using.

2.2.2 Experimental set-up

The experimental apparatus of the pyrolysis in this study is shown in Figure 2-1. The set-

up mainly consists of a horizontal fixed bed reactor.

Figure 2-1. Schematic diagram of pyrolysis process used in this experiment.

Slow pyrolysis

Holding time: 30 min

Heating rate: 10 to 20°C/min

45

2.2.3 Sample preparation

Biomasses were mixed with 3 different catalysts, Ca(OH)2, CaCO3 and CC. The ratios of

chemical catalyst/biomass were mixed at 1.0 and 3.0. The mixtures were replaced to a horizontal

fixed bed reactor. The char was produced by slow pyrolysis in a ceramic crucible at 1000oC for

30 min. The slow pyrolysis in a fixed bed reactor was done in different gas ambient including

pure N2 gas ambient by using the heating rate of 10°C/min.

To remove the catalyst in samples, the char samples were put in the magnetic stirrer that

contained 1M of HCl at 70oC for 2 hrs. In this process, catalyst was converted to water-soluble

Metal-Cl thus easily removed from char. After that, the carbon samples were rinsed with

deionized water and filtered until the pH is 7. Then, the ACs were obtained by heating the

carbon samples in an oven at 107oC for 24 hrs.

2.2.4 Characterization of the activated carbons

The SSA, pore size distribution and N2 adsorption isotherm were characterized by

nitrogen adsorption and desorption at -196oC using Brunauer-Emmett-Teller (BET) and

micropore analysis (MP) methods (BELSORP-max, Japan), respectively. Note that all samples

were degassed at 300oC for 3 hrs before the adsorption in N2 gas ambient.

2.3 Results and discussion

The results in Fig. 2-2 show specific surface area (SSA) of raw materials used in this

experiment. After pyrolysis in N2 gas ambient at 1000°C, the SSA was 200 m2/g for TS, BG,

PKS, and EFB due to normal characteristics of biomass. However, the SSA of CP has increased

to 500 m2/g. This might related to the own specific properties of CP, which still cannot be

explained.

46

TS CP BG PKS EFB0

200

400

600

800

1000

1200

14001000°C in N2

Spec

ific

surf

ace

area

[m2 /g

]

Biomass char

Figure 2-2. Specific surface area of biomass char after pyrolysis in N2 gas ambient at 1000°C.

The results in Fig. 2-3 shows the specific surface area (SSA) of activated carbon obtained

from different types of biomass mixed with various types of catalyst at the ratio of 1.0. The SSA

of TS, CP, BG, and EFB after mixed with various types of catalyst has similar values, while the

PKS has lower SSA compared to the other biomass. This is because the PKS is a hard biomass,

therefore the catalyst may not react to the PKS surface to increase pore. By adding the CaCO3

catalyst, the SSA of all types of biomass is higher compared to Ca(OH)2 and CC catalyst. This

means the CaCO3 is an effective catalyst to activate the biomass to ACs with high SSA. By

using the catalyst to biomass ratio of 1.0, the average SSA of various types of biomass is in the

range of 600 to 883 m2/g.

Typically, calcium atom (Ca) in the CaCO3 was deposited into the structure of porous

materials during pyrolysis by a mechanism called “pore blocking effect”. In this mechanism, a

discrete inorganic compound (calcium atom) is capable to form an intercalation compounds with

carbon by penetrating through an adjacent carbon layer and inserting into a graphite-like

structure. The similar mechanism caused by different additives deposited on the porous materials

has been widely reported [2, 16-18]. The pore blocking effect is widely used to describe the

47

TS CP BG PKS EFB0

200

400

600

800

1000

1200

1400Catalyst/biomass: 1/1

CaCO3

Ca(OH)2

CC

Spec

ific

surf

ace

area

[m2 /g

]

Types of biomass

Figure 2-3. Specific surface area of activated carbon obtained from different types of biomass

mixed with various types of catalyst at the ratio of 1.0.

decreasing of textual parameters. Nevertheless, washing out the Ca from the porous materials is

a simple way to substantially high porosity from micropores.

The results in Fig. 2-4 show that when the catalyst to biomass ratio has increased to 3.0, the

SSA of various types of biomass has increased to 807 to 1082 m2/g. This means, increasing of

catalyst in the process can increases the SSA. Moreover, the utilizing of CC catalyst with

catalyst to biomass ratio of 3.0, the SSA of CC catalyst has increased and comparable to CaCO3.

This might due to large amount of high porous carbon that still available in the CC. The CC

catalyst that contains fixed carbon and high porous of fixed carbon can be obtained after

pyrolysis process. Therefore, the fixed carbon in the CC catalyst can increase the total amount of

biomass in the reaction.

The results in Fig. 2-5 show the ACs yield obtained from different types of biomass mixed

with various types of catalyst at the ratio of 1.0. It was found that the ACs yield of CaCO3

catalyst has lower than Ca(OH)2 and CC catalyst, respectively. The EFB biomass with high SSA

has ACs yield around 10%. When the catalyst to biomass ratio has increased from 1.0 to 3.0, the

48

ACs yield has decreased from 10 to 0.9% in case of CaCO3 and Ca(OH)2 catalyst as the results

in Fig. 2-6.

TS CP BG PKS EFB0

200

400

600

800

1000

1200

1400Catalyst/biomass: 3/1

Spec

ific

surf

ace

area

[m2 /g

]

Types of biomass

CaCO3

Ca(OH)2

CC

Figure 2-4. Specific surface area of activated carbon obtained from different types of biomass

mixed with various types of catalyst at the ratio of 3.0.

TS CP BG PKS EFB0

5

10

15

20

25

30Catalyst/biomass: 1/1

Act

ivat

ed c

arbo

n yi

eld

[%]

Types of biomass

CaCO3

Ca(OH)2

CC

Figure 2-5. Activated carbon yield of activated carbon obtained from different types of biomass

mixed with various types of catalyst at the ratio of 1.0.

49

TS CP BG PKS EFB0

5

10

15

20

25

30Catalyst/biomass: 3/1

Act

ivat

ed c

arbo

n yi

eld

[%]

Types of biomass

CaCO3

Ca(OH)2

CC

Figure 2-6. Activated carbon yield of activated carbon obtained from different types of biomass

mixed with various types of catalyst at the ratio of 3.0.

2.4 Summary

Various types of biomasses including teak sawdust (TS), cypress (CP), bagasse (BG),

empty fruity bunch (EFB), and palm kernel shell (PKS) was used to produce activated carbon.

Among various types of catalysts, CaCO3 has higher specific surface area with lower activated

carbon yield compared to Ca(OH)2 and chicken compost (CC). This is because the pore-

blocking effects of Ca atoms and also the carbon content in the CaCO3. When the catalyst to

biomass ratio has increased from 1.0 to 3.0, the SSA of various types of biomass has increased

to 807 to 1082 m2/g. This means, increasing of catalyst in the process can increases the SSA.

50

References

[1]. E. Davida, J. Kopac. Activated carbons derived from residual biomass pyrolysis and their

CO2 adsorption capacity. Journal of Analytical and Applied Pyrolysis. 2014; 110: 322-332.

[2]. Chinnappan Baskar, Shikha Baskar, Ranjit S. Dhillon. Biomass conversion. The Interface of

Biotechnology, Chemistry and Materials Science. Springer. 91-93.

[3]. Jame Clark. Introduction to chemical from biomass. Wiley. 31-40.

[4]. Carl W. Hall. Biomass as an alternative fuel. Government Institute. 2-4.

[5]. S.H. Khalil, M.K. Aroua, W.M.A.W. Daud, Study on the improvement of thecapacity of

amine-impregnated commercial activated carbon beds for CO2 adsorbing, Chem. Eng. J.

2012; 183: 15–20.

[6]. X. Xu, J.M. Andresen, C. Song, B.G. Miller, A.W. Scaroni, Novelpolyethyleneimine

modified mesoporous molecular sieve of MCM-41 type as adsorbent for CO2 capture,

Energy Fuels. 2002; 16: 1463–1469.

[7]. M.J. Ayotamuno, R.B. Kogbara, S.O.T. Ogajib, S.D. Probert, Petroleum contaminated

ground-water: Remediation using activated carbon, Appl. Energy. 2006; 83: 1258–1264.

[8]. C. Dilek, U. Oznur, Production and characterization of activated carbon from bituminous

coal by chemical activation, Afr. J. Biotechnol. 2008; 7: 3703-3710.

[9]. Strelko Jr., D.J. Malik, M. Streat, Characterisation of the surface of oxidized carbon

adsorbents, Carbon. 2002; 40: 95–104.

[10]. N.A. Fathy, B.S. Girgis, L.B. Khalil, J.Y. Farah, Utilization of cotton stalks-biomass waste

in the production of carbon adsorbents by KOH activation for removal of dye contaminated

water, Carbon Lett. 2010; 11 (3) 224-234, http://dx.doi.org/10.5714/CL.2010.11.3.224.

[11]. P. Sugumaran, S.V. Priya, P. Ravichandran, S. Seshadri, Production and characterization of

activated carbon from banana empty fruit bunch and delonix regia fruit pod, J. Sustainable

Environ. 2012; 3: 125–132.

51

[12]. E. Taer, L.M. Deraman, I.A. Talib, A. Awitdrus, S.A. Hashmi, A.A. Umar, Preparation of

a highly porous binderless activated carbon monolith from rubber wood sawdust by a multi-

step activation process for application in super capacitors, Int. J. Electrochem. Sci. 2011; 6:

3301–3315.

[13]. A.N.A. El-Hendawy, A.J. Alexander, R.J. Andrews, G. Forrest, Effects of activation

schemes on porous, surface and thermal properties of activated carbons prepared from

cotton stalks, J. Anal. Appl. Pyrolysis. 2008; 82(2): 272–278.

[14]. S. Sjostrom, H. Krutka, T. Starns, T. Campbell, Pilot test results of post-combustion CO2

capture using solid sorbents, Energy Procedia. 2011; 4: 1584–1592.

[15]. Ribeiro AM, Loureiro JM, Simulation of toxic gases and vapours removal by activated

carbon filters, Chemical Engineering Science 2002; 57:1621-1626.

[16]. Fuente AM, Pulgar G, González F, Pesquera C, Activated carbon supported Pt catalysts:

effect of support texture and metal precursor on activity of acetone hydrogenation. J.

Applied Catalysis A: General 2001; 208: 35-46.

[17]. Kunbin Yang, Jinhui Peng, C. Srinivasakannan, Libo Zhanga, Hongying Xia, Xinhui

Duana. Preparation of high surface area activated carbon from coconut shells using

microwave heating. Bioresource Technology. 2010; 101(15): 6163-6169.

[18]. W.C. Lim, C. Srinivasakannan, N. Balasubramanian. Activation of palm shells by

phosphoric acid impregnation for high yielding activated carbon. Journal of Analytical and

Applied Pyrolysis. 2010; 88(2): 181-186.

Chapter 3

Preparation of activated carbons from teak sawdust using chicken dropping

compost and empty fruit bunch

3.1 Introduction

In recent years, agricultural by-products are generally used as feedstock in fuel

combustion. However, recycling agricultural waste as combustion fuel still lacks of profit and

efficiency. Agricultural waste especially biomass is commonly used as raw materials to produce

various value-added products in solid, liquid and gaseous forms from various conversion

processes [1-4]. This is because biomass has high carbon content and is low-cost, renewable and

environmental friendly. Among solid products, activated carbons (ACs) are the most attractive

material due to its high microporous structure, high specific surface area (SSA) and good

adsorption properties. The properties of ACs are excellent for various applications such as

wastewater treatment, pollutant removal, solvent recovery, color removal and ground water

improvement [5-9].

Typically, ACs can be produced by chemical activation and physical activation. The

chemical activation method requires a single step of carbonization at a relatively low

temperature between 400 to 700oC in the presence of chemical agents. The physical activation

method is a thermal activation process that consists of carbonization of a precursor and the

activation of a resolution char in the presence of some activating agents [10-12]. Generally, carbon

dioxide (CO2) and steam (H2O) are preferred as activating gases due to the controllability of the

oxidation process compared with O2 and air [13].

In the past, synthesis chemicals such as KOH, ZnCl2, H2SO4, NaOH and K2CO3 were

used as activating agents. However, the by-products from synthesis activating agents are harmful

and it can contaminate the surrounding environment [14]. Therefore, some research groups

53

reported that the ACs with large SSA can be produced by using natural activating agents

obtained from agricultural wastes [5-6]. Unfortunately, much agricultural waste such as rice

straw, wheat straw, pinewood and olive tree wood have SiO2 as its main component (40 to 95%)

[15]. Hence, utilizing agricultural waste still requires significant amounts of synthesis activating

agents to produce ACs.

This paper focuses on the utilizing of two different agricultural wastes including chicken

dropping compost ash (CCA) and empty fruit bunch ash (EFBA) as natural activation agents

instead of synthesized chemicals. The low cost ACs production from teak sawdust (TS) was

used as the carbon source. The effects of various parameters including the ash/biomass weight

ratio, the concentration of CO2 in reaction gas and the reaction temperature to the SSA, yield of

ACs, adsorption volume, pore size and N2 adsorption isotherm of the prepared ACs were

investigated.

3.2 Experimentals

3.2.1 Raw materials

Teak sawdust (TS) from Thailand with particle size of 0.25 to 0.50 mm was used as the

raw material. The proximate and ultimate analyses of the initial material are shown in Table 3-1.

The volatile matter and ash contents were measured by thermo gravimetric analyzer (TGA 701,

Leco Co., Ltd.). The content of C, H, N and O elements were determined using an elemental

analyzer (TruSpec CHN, version 100, Leco Co., Ltd) and the content of sulfur element was

analyzed by sulfur analyzer (Leco SC-432, Leco Co., Ltd). The TS was dried at 107oC for 1 hour

before mixed with biomass ashes.

54

Table 3-1 Proximate and ultimate analysis of the teak sawdust

Proximate analysis (%wt) Ultimate analysis (%wt, daf)

Moisturear Volatiled Ashd Fixed carbonb C H N S Ob

7.48 76.77 0.83 22.40 50.02 9.49 0.29 0.12 40.08

ar: as-received, d: air-dried basis and b: by difference

The chicken dropping compost (CC) was obtained from Kinsei Sangyo Co., Ltd., Japan.

The CCA was prepared by TGA in oxygen gas ambient with temperature variations from 500 to

815oC with the heating rate of 10oC/min and stabilized at 815oC for 30 min. The CCA was then

cooled down to room temperature and was kept for further use. The empty fruit bunch (EFB)

was obtained from Chemical Engineering Department, Universiti Teknologi Petronas, Malaysia.

Note that the preparation condition of EFBA is similar to the process condition used for CCA.

3.2.2 Sample preparation

TS was mixed with two different biomass ashes, CCA and EFBA. Both CCA/TS and

EFBA/TS weight ratio were varied from 0.6 to 1.0 and the mixtures were replaced to a

horizontal fixed bed reactor. The char was produced by slow pyrolysis in a ceramic crucible at

600 to 1000oC for 30 min. The slow pyrolysis in a fixed bed reactor was done in different gas

ambient including pure N2 and N2/CO2 gas ambient by using the heating rate of 10oC/min.

To remove the ash components in CCA and EFBA, the char samples were put in the

magnetic stirrer that contained 1M of HCl at 70oC for 2 hrs. In this process, metal oxide was

converted to water-soluble Metal-Cl thus easily removed from char. After that, the carbon

samples were rinsed with deionized water and filtered until the pH is 7. Then, the ACs were

obtained by heating the carbon samples in an oven at 107oC for 24 hrs.

55

3.2.3 Characterization of the activated carbons

The SSA, pore size distribution and N2 adsorption isotherm were characterized by

nitrogen adsorption and desorption at -196oC using Brunauer-Emmett-Teller (BET) and

micropore analysis (MP) methods (BELSORP-max, Japan), respectively. Note that all samples

were degassed at 300oC for 3 hrs before the adsorption in N2 gas ambient.

3.3 Results and discussion

3.3.1 Preparation of ACs from TS mixed with CCA activating agent

3.3.1.1 Effects of CCA activating agent

Fortunately, CCA and EFBA contains low amount of SiO2 component (< 20%) as the

information shown in Table 3-2. The composition of CCA contains high amount of calcium

oxide, CaO (∼ 85%) and the composition of EFBA contains high amount of potassium oxide,

K2O (∼ 77%). Therefore, CCA and EFBA are very interesting activating agents to produce ACs

without using any synthesized chemicals in the activating process. Figure 3-1 shows the SSA of

TS and ACs obtained from TS mixed with CCA activated with N2 gas stream at 1000oC. By

adding the CCA catalyst, the SSA of TS has increased from 192 to 930 m2g-1. This means the

CCA is an effective catalyst to activate the TS to ACs with high SSA.

Table 3-2 Composition of metal oxide in CCA and EFBA

Biomass ash Metal oxide composition (wt%, dry basis)

K2O SiO2 CaO P2O5 Fe2O3 SO3

CCA 11.06 1.27 84.65 2.58 0.29 0.14

EFBA 76.94 18.17 3.46 0 1.01 0.16

56

0

200

400

600

800

1000

TS+CCATSType of biomass

Spec

ific

surf

ace

area

[m2 g

-1]

Figure 3-1. Specific surface area of TS and TS mixed with CCA.

Typically, calcium oxide (CaO) in the CCA was deposited into the structure of porous

materials during pyrolysis by a mechanism called “pore blocking effect”. In this mechanism, the

ash that contains a discrete inorganic compound (calcium atom) is capable to form an

intercalation compounds with carbon by penetrating through an adjacent carbon layer and

inserting into a graphite-like structure. The similar mechanism caused by different additives

deposited on the porous materials has been widely reported [2, 16-18]. The pore blocking effect is

widely used to describe the decreasing of textual parameters. Nevertheless, washing out the CaO

from the porous materials is a simple way to substantially high porosity from micropores.

3.3.1.2 Effects of ash to biomass weight ratio

The results in Fig. 3-2 show the evolution of ACs produced by slow pyrolysis using the

TS mixed with CCA. The amount of activation agent mixed with CCA and TS was varied at the

weight ratio of 0.6 to 1.0. It was found that when the ash to biomass weight ratio has increased

57

from 0.6 to 1.0, the SSA has increased from 684 to 930 m2g-1 and carbon yield of ACs has

decreased from 18.9 to 13.1%, respectively.

The decrease of ACs yield by increasing the ash to biomass weight ratio can be explained

by the reaction rate of metal elements with the char and volatile matter. By using high ash to

biomass weight ratio, the activation of TS has increased and the by-products can be quickly

diffused out from the particles surface during activation process [19]. Therefore, the gasification

of carbon atom surface becomes predominant that leads to decrease the weight loss and ACs

yield. Figure 3-3 exhibits the N2 adsorption isotherm of ACs obtained from carbonization

process in N2 gas stream with different ash to biomass weight ratio. The appearance of isotherm

clearly shows the Type I, which is the characteristic of microporous materials [20].

0

200

400

600

800

1000

1200

1.00.80.6

N2 ambient

Sp

ecifi

c su

rfac

e ar

ea [m

2 g-1]

SSA ACs yield

Ash/biomass weight ratio

0

10

20

30

40 Activated carbon yield [%

]

Figure 3-2. Specific surface area and yield of ACs with different CCA to biomass weight

ratio.

58

0 0.2 0.4 0.6 0.8 1.00

200

400

600

800

N2 ambient

Ash/Biomass weight ratio1.00.80.6

Relative pressure [P/P0]

Ads

orpt

ion

volu

me,

Va [m

3 g-1

]

Figure 3-3. Adsorption isotherm of ACs with different CCA to biomass weight ratio.

3.3.1.3 Effects of carbonization gas ambient using CCA activating

agent

The results in Fig. 3-4 show that the main effect of gasification with N2/2%CO2 gas is the

creation and widening of the existing pores. This can improve the adsorption properties such as

SSA. By using N2/2%CO2 activation at 1000oC, the SSA of TS has increased from 196 to 600

m2g-1. The increasing of SSA can be explained by the “burn off” reaction. In the burn off

reaction, CO2 reacts with carbon to produce CO during the thermal activation by reaction

mechanism in Eq. 1. The CO2 can increase an amount of the activating gas in the reaction.

Moreover, it can enhance the bulk mass transfer of the CO product from the burn off reaction [21].

C+CO2 à 2CO ΔH = +159 kJ/mol (1)

59

0

200

400

600

800

1000

N2/2% CO2N2Carbonization gas ambient

Spec

ific

surf

ace

area

[m2 . g

-1]

Figure 3-4. Specific surface areas of the ACs from TS prepared in pure N2 and N2/2%CO2

gas ambient at the carbonization temperature of 1000oC.

3.3.1.4 Effects of carbonization temperature using CCA activating

agent on CO2 gas

The results in Fig. 3-5 show the SSA and ACs yield obtained from TS and TS mixed

with CCA using carbonization process with N2/2%CO2 gas ambient at various carbonization

temperatures. When the carbonization temperature has increased from 600 to 1000oC, the SSA

has increased from 400 to 1094 m2 g-1 but the ACs yield has decreased from 24.4 to 6.3%,

respectively. By using the combination of chemical and physical activation, the SSA of ACs is

higher than the one that obtained from chemical activation. Table 3-3 shows the characterization

parameters of the ACs obtained from the carbonization process including yield of activated

carbon (Yacs), SSA, volume of microporous (Vmicro), total volume of ACs (Vtotal) and average

diameter of ACs (Davg). The volume of microporous has increased by increasing the activation

temperature.

60

Figure 3-5. Specific surface area and ACs yield obtained from carbonization process in

N2/2%CO2 gas ambient by varied the carbonization temperature from 600 to 1000oC.

Table 3-3 Parameters of the activated carbon obtained from the carbonization process

Sample Carbonization

temperature

[oC]

Gas

ambient

CCA

to TS

ratio

YAcs

[%]

SSA

[m2g-1]

Vmicro

[cm3g-1]

Vtotal

[cm3g-1]

Davg

[nm]

AC1 1000 N2 0.6 13.6 684 0.33 0.48 2.80

AC2 1000 N2 0.8 10.7 820 0.40 0.55 2.67

AC3 1000 N2 1.0 7.0 1006 0.42 1.15 2.55

AC4 600 N2/2%CO2 1.0 24.4 400 0.16 0.34 2.39

AC5 600 N2/5%CO2 1.0 23.6 482 0.22 0.36 2.94

AC6 600 N2/10%CO2 1.0 21.8 554 0.22 0.40 3.21

AC7 800 N2/2%CO2 1.0 13.7 897 0.43 0.57 2.30

AC8 1000 N2/2%CO2 1.0 6.3 1093 0.51 0.63 2.31

61

Figure 3-6. Pore size distribution obtained from carbonization process with N2/2%CO2 gas

ambient at different carbonization temperatures.

Figure 3-6 show the pore size distribution of ACs obtained from carbonization process

with N2/2%CO2 gas ambient at different carbonization temperatures. When the carbonization

temperature has increased from 600 to 1000oC, the pore size distribution of ACs decreased from

0.7 to 0.5 nm, respectively. However, the pore size distribution of ACs in the range of 0.8 to 1.0

nm has increased as the carbonization temperature increased.

The carbonization is a complex reaction process that includes the decomposition of

organic matter and the elimination of volatile matter in the remaining products. At the

carbonization temperature of 450oC, the volatile matter start to accumulate in the particles

undergoes the first cracking, which can generate pores on the materials surface. When the

carbonization temperature is higher than 450oC, the volatile matters start to escapes from the

particles undergoes the secondary cracking. It can form carbon to deposit on the char thus

blocking the developed pore and leads to decrease the surface area of microspore [22]. The

0 0.4 0.8 1.2 1.6 2.00

1000

2000

3000

4000

5000

6000

dVp/d

(dp)

Pore size [nm]

1000°C800°C600°C

2% CO2 ambient

62

continuous of secondary cracking at higher carbonization temperature can collapse the

micropores size of 0.4 to 0.7 nm and generate the bigger pore with the size of 0.8 to 1.2 nm.

The dependence of SSA, ACs yield and pore size distribution on the carbonization

temperature can be explained by the burn off mechanism. The products burn off at low

carbonization temperature is smaller than the high carbonization temperature. Therefore, the

amount of volatile matter in the products that was obtained from high carbonization

temperatures is smaller than the one that obtained from low carbonization temperature. The loss

of volatile materials was related to the high SSA of ACs [23-24].

3.3.1.5 Effects of CO2 concentration in carbonization process using

CCA activating agent

The effects of N2/CO2 gas ratio to the SSA and the yield of ACs using the CCA

activation agent at 600oC were investigated. In this experiment, the CO2 concentration of

N2/CO2 gas was varied from 2 to 10%. The results in Fig. 3-7 show that when the CO2

concentration has increased from 2 to 10%, the SSA has increased from 400 to 555 m2g-1.

However, the ACs yield has decreased by increasing the CO2 concentration. This means, higher

CO2 concentration is more efficient in removing the volatile matters from the activating mass.

This can be explained by the reaction between carbon and CO2 in the activation process. The

carbon was removed and then exposed to the aromatic carbon sheets to the action of CO2 gas [25-

27]. Based on the results in Fig. 3-7, it can be predicted that if the CO2 concentration is less than

2%, SSA trends to decreases and ACs yield trends to increases, respectively. In contrast, if the

CO2 concentration is excessively increases, the burn off reaction will be strongly occurred.

Therefore, the CO2 could react with all of carbon in TS and the ACs products will not remain

after carbonization process.

63

Figure 3-7. Specific surface area and ACs yield with different CO2 concentration in N2/CO2

gas ambient at 600oC.

3.3.2 Comparison of CCA and EFBA activating agents

Figure 3-8 show the comparison of the SSA of ACs obtained from TS mixed with CCA and

TS mixed with EFBA at different ash/biomass weight ratio. The carbonization was done in

different gas ambient at 1000oC. By using an EFBA activating agent, the SSA has higher

compared to CCA activating agent. This is related to the different composition of EFBA that

contains potassium oxide (K2O) and CCA that contains calcium oxide (CaO) as shown in Table

3-2. The ACs with high SSA can produce from biomass that contains the potassium compound.

This could be explained by the carbon gasification of CO2 by-product to the decomposition of

potassium compound.

0 2 4 6 8 10 120

200

400

600

800

1000

1200

at 600°C

Sp

ecifi

c su

rfac

e ar

ea [m

2 g-1]

SSA ACs yield

CO2 concentration [%]

0

10

20

30

40 Activated carbon yield [%

]

64

600

800

1000

1200

1400

1.0 (N2/2% CO2)1.0 (N2)0.8 (N2)0.6 (N2)

TS + CCATS + EFBA

Carbonization gas ambient

Spec

ific

surf

ace

area

[m2 g

-1]

Figure 3-8. Specific surface area of ACs from TS mixed with CCA and EFBA by varied the

ash/biomass weight ratio from 0.6 to 1.0 and carbonized in different gas ambient at 1000oC.

Moreover, high SSA obtained from potassium compound can be attributed to the particle

reaction of the potassium with the cellulose in biomass [28]. Due to the ionic strength of calcium

cation being weaker than potassium cation, the catalytic activity during pyrolysis of calcium is

less than potassium. Moreover, the combination of chemical activation and physical activation

process can increase the SSA of TS by the reaction of metal oxide and CO2 gas.

Finally, the pore size distribution of the activated carbon obtained from TS mixed with

CCA and TS mixed with EFBA is shown in Figure 3-9. The pore size of ACs was varied from

0.4 to 2.0 nm. The maximum volume (means of normal distribution) of the pore size was located

at 0.5 nm. Therefore, the average pore size of the ACs obtained from TS mixed with CCA and

TS mixed with EFBA were 0.5 nm.

65

0 0.4 0.8 1.2 1.6 2.00

2000

4000

6000

8000TS + CCATS + EFBA

dVp/d

(dp)

Pore size [nm]

Figure 3-9. Pore size distribution of ACs from TS mixed with CCA and EFBA with the

ash/biomass weight ratio of 1.0 and carbonized in N2 gas ambient at 1000oC.

3.4 Conclusions

Activated carbon (ACs) can be produced from teak sawdust

(TS) mixed with two different biomass activation agents including chicken dropping compost

ash (CCA) and empty fruit bunch ash (EFBA). The specific surface area (SSA) of ACs over

1000 m2g-1 can be obtained for both CCA and EFBA after physical activation process in

N2/2%CO2 gas ambient at 1000oC. However, the potassium compound (K2O) in EFBA has more

efficiency to increase the SSA compared to the calcium compound (CaO) in CCA.

66

References

[1] Mohamed R A, Mohammadi M, Darzi N G, Preparation of carbon molecular sieve from

lignocellulosic biomass: A review, Renew. Sustainable Energy Rev. 2010; 14: 1591-

1599.

[2] Przepiorski J, Czyżewskia A, Pietrzakb R, Toyodac M, Morawsk W A, Porous carbon

material containing CaO for acidic gas capture: Preparation and properties, J. Hazard.

Mater. 2013; 263: 353-360.

[3] Nor M N, Chung L L, Teong K L, Mohamed R A, Synthesis of activated carbon from

lignocellulosic biomass and its application in air pollution control-a review, J.

Environmental Chem. Eng. 2013; 1: 658-666.

[4] Savova D, Apak E, Ekinci E, Yardim F, Petrov N, Budinova T, Razvigorova M,

Minkova V, Biomass conversion to carbon adsorbent and gas, Biomass Bioenergy.

2001; 21: 133-142.

[5] Koutcheiko S, Monreal M C, Kodama H, McCracken T, Kotlyar L, Preparation and

characterization of activated carbon derived from the thermal-chemical conversion of

chicken manure, Bioresour. Technol. 2007; 98:2459-2464.

[6] Sato K, Suemune S, Nitta K, Nakayama C, Inokuma S, Tonooka S, Mamada Y,

Nakamura E, Kaneko K, Takarada T, A simple fabrication route of activated carbon

from chicken dropping, J. Anal. Appl. Pyrolysis. 2013; 101: 86-89.

[7] Okman I, Karagoz S, Tay T, Erdem M, Activated carbons from grape seeds by

chemical activation with potassium carbonate and potassium hydroxide, Appl. Surf.

Sci. 2014; 293: 138-142.

67

[8] Lu X, Jiang J, Sun K, Xie X, Hu Y, Surface modification, characterization and

adsorptive properties of a coconut activated carbon, Appl. Surf. Sci. 2012; 258: 8247-

8252.

[9] Stavropoulos G G, Zabaniotou A A, Production and characterization of activated

carbons from olive-seed waste residue, Microporous Mesoporous Mater. 2005; 82: 79-

85.

[10] Girgis S B, Yunis S S, Soliman M A, Characteristics of activated carbon from peanut

hulls in relation to conditions of preparation, Mater. Lett. 2002; 57: 164-172.

[11] Oh H G, Park R C, Preparation and characteristics of rice-straw-based porous carbons

with high adsorption capacity, Fuel 2001; 81: 327-336.

[12] Sudaryanto Y, Hartono B S, Irawaty W, Hindarso H, Ismadji S, High surface area

activated carbon prepared from cassava peel by chemical activation, Bioresour.

Technol. 2006; 97: 734-739.

[13] Yahya A M, Qodah A Z, Ngah Z W C, Agricultural bio-waste materials as potential

sustainable precursors used for activated carbon production: A review, Renew.

Sustainable Energy Rev. 2015; 46: 218-235.

[14] Qodah A Z, Shawabkah R, Production and characterization of granular activated

carbon from activated sludge, Braz. J. Chem. Eng. 2009; 26: 127-136.

[15] Vassilev V S, Vassileva G C, Baxter D, Trace element concentrations and associations

in some biomass ashes, Fuel 2014; 129: 292-313.

[16] Vassilev V S, Baxter D, Andersen K L, Vassileva G C, An overview of the

composition and application of biomass ash. Part 2. Potential utilization, technological

and ecological advantages and challenges, Fuel 2013; 105: 19-39.

68

[17] Wang J, Cheng M, Wang C, Wang J, Zheng J, Preparation of mesoporous carbons

from amphiphilic carbonaceous material for high-performance electric double-layer

capacitors, J. Power Sources. 2011; 196: 550-558.

[18] Xu B, Wub F, Sub Y, Caoa G, Chenb S, Zhoub Z, Yanga Y, Competitive effect of

KOH activation on the electrochemical performances of carbon nanotubes for EDLC:

Balance between porosity and conductivity, Electrochim. Acta. 2008; 53: 7730-7735.

[19] Zhao Y X, Huang S S, Cao P J, Xi C S, Wei Y X, Kamamoto J, Takarada T, KOH

activation of a HyperCoal to develop activated carbons for electric double-layer

capacitors, J. Anal. Appl. Pyrolysis. 2014; 105: 116-121.

[20] Sing W S K, Everett H D,. Haul W A R, Moscou L, Pierotti A R, Rouquerol J, Pierotti

A R, Rouquerol J, Siemieniewska T, Reporting physisorption data for gas/solid

systems with special reference to the determination of surface area and porosity, Pure

Appl. Chem. 1985; 57: 603-619.

[21] Jung S, Kim J, Production of biochars by intermediate pyrolysis and activated carbons

from oak by three activation methods using CO2, J. Anal. Appl. Pyrolysis. 2014; 107:

116-122.

[22] Kan Y, Yue Q, Gao B, Li Q, Preparation of epoxy resin-based activated carbons from

waste printed circuit boards by steam activation, Mater. Lett. 2015; 159: 443-446.

[23] Zhang T, Walawender P W, Fan T L, Fan M, Daugaard D, Brown C R, Preparation of

activated carbon from forest and agricultural residues through CO2 activation, Chem.

Eng. J. 2004; 105: 53-59.

[24] Lua C A, Yang T, Guo J, Effects of pyrolysis conditions on the properties of activated

carbons prepared from pistachio-nut shells, J. Anal. Appl. Pyrolysis. 2004; 72: 279-

287.

69

[25] Karaman I, Yagmur E, Banford A, Aktas Z, The effect of process parameters on the

carbon dioxide based production of activated carbon from lignite in arotary reactor,

Fuel Process. Technol. 2014; 118: 34-41.

[26] Hesas H R, Arami-Niya A, Daud W A M W, Sahu N J, Microwave-assisted production

of activated carbons from oil palm shell in the presence of CO2 or N2 for CO2

adsorption, J. Indus. and Eng. Chem. 2014; 24: 196-205.

[27] David E, Kopac J, Activated carbons derived from residual biomass pyrolysis and their

CO2 adsorption capacity. J. Anal. Appl. Pyrolysis. 2014; 110: 322-332.

[28] Tsai T W, Changb Y C, Wangb Y S, Changb F C, Chiena F S, Sun F H, Preparation of

activated carbons from corn cob catalyzed by potassium salts and subsequent

gasification with CO2, Bioresour. Technol. 2001; 78: 203-208.

Chapter 4

Catalytic effects of biomass on Loy Yang brown coal gasification

4.1 Introduction

In recent years, carbon dioxide (CO2) is the primary greenhouse gas that is emitted

through human activities such as the combustion of fossil fuels from transportation and

industrial process. The CO2 gas in the atmosphere acts like radiative active gas, which

radiates energy in all directions. Part of this radiation is directed towards the earth surfaces,

thus warming it. This process is the fundamental cause of the greenhouse effect, which has an

impact to the global climate change [1]. To meet emission limitations of CO2, the novel

technologies that limit the fossil fuel processing is necessary to be developed. Among

important technologies, gasification process is found to be promising for dealing with the

commercial-scale release of CO2.

It is well known that the gasification is a series of processes producing synthesis gas such

as H2 and CO from carbonaceous materials. Over the past several years, the concept of

polygeneration gasification technology that combines power generation with chemical

production from synthesis gases were considered. Therefore, most of current research works

focus on the increasing of gasification process performance. As presented elsewhere, the

pressurized CO2 enriched gasification of coal is considered as competitive to conventional

gasification technology [2].

In coal gasification, the first stage starts with a rapid de-volatilization, leaving a char

mainly composed of carbon. The second stage is the gasification of a nascent char that can be

converted to fuel gas [3-5]. The fuel gas can be used instead of synthetic biofuel for feeding

gas engines and gas turbines. The most important heterogeneous reaction, which takes place

71

during the gasification process, is the carbon conversion by reaction mechanism shown in

Eq. 4-1.

C + CO2→2CO (4-1)

It was reported that the catalytic gasification technique has more efficiency to improve

the reaction rate and the conversion efficiency by using lower reaction temperature compared

to conventional gasification techniques [6-9]. Generally, the coal gasification with CO2 is a

high temperature process but low temperature gasification is desired to reduce the total

process cost. Therefore, the use of catalysts has been proposed for low temperature

gasification to overcome the slow reaction rate of carbon with CO2. The previous works

reported that hydroxide, oxide of alkaline and alkaline earth metal (AAEM), transition metal

salts, and partial transition metals are effective catalysts on coal char gasification. AAEM

catalysts are mostly used as effective catalysts [10-14].

For catalytic gasification of low rank coals, the mineral matters from catalyst such as

sodium and calcium occur as cations during the gasification process that associated with

carbonaceous matrix. By heating coals into the temperature range of 400°C or above, the

carboxyl groups are destroyed and left the associated cations behind the resulting char that

leads to the formation of highly dispersed metals. Those highly dispersed metals composing

mineral matter in the carbonaceous matrix can be used as a catalyst to increase the

gasification rate.

For the sub-bituminous char, the catalytic effects due to mineral matter content were

detected up to 1060oC. However, the current gasification temperature is too high to meet the

economic point-of-view [15]. Fortunately, the iron-loaded on activated carbon or carbon black

has high activity in the CO2 gasification that yields the rapid gasification. Both steps in the

72

oxidation and reduction of iron species proceeded very fast. However, the key step for the

CO2 gasification is the oxidation step of iron metal in the redox cycle [16].

This paper focuses on the utilizing of Loy Yang brown coal (LY) as natural starting

material for CO2 gasification. The char conversion of LY mixed with two different types of

ash was measured to investigate the catalytic effect of the ash. The two ash samples were

prepared from chicken dropping compost (CC) and empty fruit bunch (EFB). The effects of

various parameters including the type of catalyst and gasification temperature on the char

conversion profile of the CO2 gasification process were investigated.

4.2 Experimental

4.2.1 Materials

Loy Yang brown coal (LY) from Australia, which contains low ash content with the size

between 0.5 to 1.0 mm, was used as a raw material. The proximate and ultimate analyses of

the LY are shown in Table 4-1. The moisture, volatile matter and ash contents were measured

by a thermogravimetric analyzer (TGA 701, Leco Co., Ltd.). The content of C, H, N and O

elements were determined using an elemental analyzer (TruSpec CHN, version 100, Leco Co.,

Ltd). The LY was dried in an oven at 107°C for 1 hour before mixed with biomass ashes. The

moisture content of LY was 18 wt%.

In this experiment, two types ash prepared from empty fruit bunch (EFB) from Malaysia

and chicken dropping compost (CC) from Japan with the size between 0.5 to 1.0 mm were

used as catalysts. The chicken dropping compost ash (CCA) and empty fruit bunch ash

(EFBA) were prepared by TGA in O2 gas with temperature ramping from 500 to 815°C.

After heating up to 815ºC, the temperature was maintained for 30 min, then cooled down to

room temperature.

73

Table 4-1 Proximate and ultimate analysis of the Loy Yang brown coal

Proximate analysis

(wt%, dry basis)

Ultimate analysis

(wt%, dry basis)

Volatile matter Ash Fixed carbon C H N O (diff)

52.36 0.93 46.71 63.79 7.01 0.62 28.58

4.2.2 Catalytic gasification

LY sample was mixed with two different biomass ashes, CCA and EFBA, and two

different chemical reagents, K2CO3 and CaCO3. In this experiment, the designations of LY

mixed with EFBA, LY mixed with CCA, LY mixed with K2CO3 and LY mixed with CaCO3

are LY1, LY2, LY3, and LY4, respectively.

The coal char was produced by TGA at maximum heat treatment of 650 to 800oC for 30

min. The heating rate was at 100oC/min under pure Ar gas atmosphere. The samples were

continuously gasified under a CO2 gas ambient for 2 hours. The initial char mass of dry ash

free (m0) and the instantaneous of char mass of dry ash free (mt) were calculated by

subtraction the weight of initial char mass (w0) and the weight of instantaneous char mass

(wt) that obtained from TGA with the weight of ash (wa). Hence, the char conversion (Xch)

can be calculated by using the fraction of weight loss as shown in the Eq. 4-2 given below;

𝑋!! =!!!!!!!

= (!!!!!)!(!!!!!)(!!!!!)

(4-2)

4.3 Results and Discussion

4.3.1 Characteristic of biomass ash

Forest residues and wood wastes represent a large potential resource for long-term

renewable energy. In general EFB and CC are abundant in Malaysia and Japan, respectively.

Generation of EFB and CC amounts to 19 and 13 million tons per year, respectively.

74

Table 4-2 Elements of biomass ash

Biomass ash Elemental composition (wt%, dry basis)

K Si Ca P Fe S Cl

EFBA 62.1 15.7 7.5 － 1.4 1.3 10.9

CCA 10.0 0.7 83.3 2.4 1.5 0.6 -

Fortunately, EFBA and CCA contain low amount of Si component (< 20 wt%) as the

information shown in Table 4-2. EFBA contains high amount of potassium, K (∼ 62 wt%)

and CCA contains high amount of calcium, Ca (∼ 83 wt%). Therefore, EFBA and CCA are

very interesting catalysts for catalytic gasification. After ash preparation, the biomass ash was

characterized by X-ray diffraction (XRD) method. For EFBA, the potassium was observed in

the form of potassium chloride (KCl) and potassium sodium calcium phosphate

(KNaCa2(PO4)2) as shown in Fig. 4-1. On the other hand, the calcium in CCA was observed

in the form of calcium hydroxide (Ca(OH)2), calcium silicate hydrate (CaSiO3H2O) and

Calcic ferrite (CaFe4O7) as shown in Fig. 4-2.

The presence of metal complex compounds after ash preparation in Figs. 4-1 and 4-2

might be explained by the following mechanism. During the preparation of CCA by

combustion under O2 atmosphere at 815°C for 30 min, many complex chemical reactions

occurred. Therefore, the exact mechanism of the compounds formation cannot be explained.

However, the results in Table 4-2 show that the main components of CCA include various

metal elements such as K, Si, Ca, P, Fe and S. These elements in CCA, especially Ca (83.3

wt%), K (10 wt%) and Fe (1.5 wt%), reacted with oxygen during the combustion process and

formed complex compounds such as calcium hydroxide (Ca(OH)2), calcium silicate hydrate

(CaSiO3H2O) and Calcic ferrite (CaFe4O7) as the XRD patterns shown in Fig. 4-2. The

75

presence of potassium sodium calcium phosphate (KNaCa2(PO4)2) from EFBA also might be

explained by the similar mechanism.

10 20 30 40 50 60 70 80 90

Inte

nsity

[arb

. uni

t]

2θ [degree]

EFBAx

•

•

x

• xx x

•: KNaCa2(PO4)2

x: KCl

Figure 4-1. XRD patterns of EFBA.

10 20 30 40 50 60 70 80 902θ [degree]

Inte

nsity

[arb

. uni

t]

CCA

•ο

•ο

x

x

ο: CaFe4O7

•: CaSiO3H2Ox: Ca(OH)2

Figure 4-2. XRD patterns of CCA.

76

4.3.2 Effect of gasification temperature on LY char conversion

The gasification temperature is one of the most important parameters to control the

gasification rate and conversion [17-20]. In this experiment, the gasification temperature was

varied at 650, 700, 750 and 800oC. The CO2 gasification profiles of LY char are shown in

Fig. 4-3. It was found that when the gasification temperature increased from 650 to 800oC,

the char conversion at 120 min gradually increased from 0.1 to 0.4.

4.3.3 Effects of biomass ash contents

The results in Fig. 4-4 show that when the EFBA content of LY1 char in catalytic

gasification increased from 2 to 10 wt%, the char conversion increased due to the catalytic

effect of potassium. This trend may be attributed to increase in the interaction between active

metal and char surface with increase in EFBA content. The catalytic effect of potassium for

EFBA-catalyzed CO2 gasification of LY char can be explained by the redox mechanism.

Under gasification conditions, the oxidation and the reduction occur concurrently. The

catalytic reduction involves a series of reaction in catalyst.

During gasification process, the completely reduced group is readily decomposed to

free potassium, sodium and calcium metals, which are easily vaporized at the gasification

temperatures. After the reduction process was completed, the catalyst was oxidized by CO2

and the gasification process was initialized. The active metal ions are connected to the

carboxylic and phenolic groups to form active sites on coal surface to perform the catalytic

activity [21-23].

77

0 30 60 90 1200

0.2

0.4

0.6

0.8

1.0LY char

Con

vers

ion

[-]

Time [min]

650°C700°C750°C800°C

Figure 4-3. CO2 gasification profiles of LY char.

0 30 60 90 1200

0.2

0.4

0.6

0.8

1.0

700°C

LY charLY1 char (2 wt%)LY1 char (5 wt%)LY1 char (10 wt%)

Con

vers

ion

[-]

Time [min]

Figure 4-4. CO2 gasification profiles of LY1 char at different EFBA contents of 2 to 10 wt%.

78

4.3.4 Effect of biomass-derived ash type

The catalytic CO2 gasification profiles of LY1 char (10 wt% of EFBA) and LY2 (10

wt% of CCA) char at various gasification temperatures are shown in Figs. 4-5 and 4-6,

respectively. It was found that the catalytic gasification rate and conversion are dependent on

the type of biomass-derived ash added to char as a catalyst. The conversion of both LY1 char

and LY2 char reached 100% when the gasification temperature was 800oC. This means that

the catalytic activity is strongly dependent on the reaction temperature and a high gasification

temperature is required to obtain a high conversion rate.

The results in Fig. 4-3 show that the char conversion of pure LY was very low. However,

the char conversion of LY1 (10 wt% of EFBA) linearly increased at the beginning stage and

then asymptotically decreased towards the end of the reaction as shown in Fig. 4-5. When the

gasification temperature is higher than 700oC, the char conversion reached the maximum

value (1.0). Increasing the gasification temperature from 750 to 800oC can decrease the

duration time to reach the maximum conversion from 60 to 30 min. It was confirmed that the

reaction rate is strongly dependent on the gasification temperature.

The results in Fig. 4-6 show the conversion of LY2 char (10 wt% of CCA). The char

conversion of LY2 increased twice compared to that of pure LY at gasification temperatures

between 650 to 700oC. When the reaction temperature is higher than 750oC, the char

conversion reached the maximum value (1.0). The increasing of char conversion of LY2 (10

wt% of CCA) with temperature might be related to the formation of crystalline layer of Ca on

char surface and the adsorption of CO2 by Ca(OH)2 before the CO2 gasification occurs.

The results in Figs. 4-7 and 4-8 show then XRD patterns of LY1 char (10 wt% of EFBA)

and LY2 char (10 wt% of CCA), respectively. It was found that after the gasification process,

the components of raw materials remained by comparing these results with the results shown

in Figs 4-1 and 4-2, respectively.

79

0 30 60 90 1200

0.2

0.4

0.6

0.8

1.0C

onve

rsio

n [-

]

Time [min]

LY1 char (10 wt%)

650°C700°C750°C800°C

Figure 4-5. CO2 gasification profiles of LY1 char (10 wt% of EFBA).

0 30 60 90 1200

0.2

0.4

0.6

0.8

1.0

Con

vers

ion

[-]

Time [min]

LY2 char (10 wt%)650°C700°C750°C800°C

Figure 4-6. CO2 gasification profiles of LY2 char (10 wt% of CCA).

80

10 20 30 40 50 60 70 80 90

•

xxx

x • xIn

tens

ity

[arb

. uni

t]

2θ [degree]

LY1 char (10 wt%)

•: KNaCa2(PO4)2

x: KCl

650°C700°C750°C800°C

•

Figure 4-7. XRD patterns of LY1 char (10 wt% of EFBA) after CO2 gasification.

10 20 30 40 50 60 70 80 90

800°C750°C700°C650°C

•

Inte

nsit

y [a

rb. u

nit]

2θ [degree]

LY2 char (10 wt%)

•x

ο

ο: CaFe4O7

•: CaSiO3H2O

x: Ca(OH)2xο

Figure 4-8. XRD patterns of LY2 char (10 wt% of CCA) after CO2 gasification.

81

600 650 700 750 800 8500

0.2

0.4

0.6

0.8

1.0

Con

vers

ion

[-]

Temperature [°C]

LY charLY1 char (10 wt%)LY2 char (10 wt%)

Figure 4-9. Effect of gasification temperature on the conversion of LY char with and without

mixing with 10 wt% of EFBA and 10 wt% of CCA.

The result in Fig. 4-9 shows the effect of gasification temperature on the char

conversion of LY without ash, LY1 (10 wt% of EFBA) and LY2 (10 wt% of CCA). It was

found that the char conversion rate of LY without mixing ash (LY char) is lower than that of

the LY mixed with ashes. This means that when LY is mixed with the ashes, the efficiency of

conversion increased. The conversion rate increased when the gasification temperature

increased. Moreover, LY1 char (10 wt% of EFBA) has higher reactivity than LY2 char (10

wt% of CCA).

4.3.5 Comparison of chemical reagent with ash

The results in Figs. 4-10 and 4-11 show the comparison of char conversion with

biomass ashes and chemical reagents at 700°C. Fig. 4-10 shows the LY1 char (10 wt% of

EFBA) is more effective in char conversion compared to the LY3 char (10 wt% of K2CO3)

when the gasification time is longer than 30 min. However, the char conversion of LY3 char

82

(10 wt% of K2CO3) is slightly higher than LY1 char (10 wt% of EFBA) when the gasification

time is shorter than 30 min. On the contrary, the conversion of LY4 char (10 wt% of CaCO3)

is similar to LY2 char (10 wt% of CCA) as shown in Fig. 4-11.

0 30 60 90 1200

0.2

0.4

0.6

0.8

1.0

700°C

Con

vers

ion

[-]

Time [min]

LY1 char (10 wt%)LY3 char (10 wt%)

Figure 4-10. Comparison of conversion of LY1 char (10 wt% of EFBA) and LY3 char (10

wt% of K2CO3) at 700°C.

0 30 60 90 1200

0.2

0.4

0.6

0.8

1.0

Con

vers

ion

[-]

Time [min]

LY2 char (10 wt%)LY4 char (10 wt%)

700°C

Figure 4-11. Comparison of conversion of LY2 char (10 wt% of CCA) and LY4 char (10

wt% of CaCO3) at 700°C.

83

10 20 30 40 50 60 70 80 90

: K2CO3

♦

Inte

nsity

[arb

. uni

t]

2θ [degree]

700°C

LY3 char (10 wt%)

LY1 char (10 wt%)

∇: KCl

∇•♦ ∇

♦ ∇∇ ∇

♦: KNaCa2(PO4)2

Figure 4-12. XRD patterns of LY1 char (10 wt% of EFBA) and LY3 char (10 wt% of

K2CO3) after gasification at 700°C.

10 20 30 40 50 60 70 80 90

∗: CaCO3

Inte

nsity

[arb

. uni

t]

2θ [degree]

∗ ∗∗ ∗∗

∗

∗

LY2 char (10 wt%)

LY4 char (10 wt%)

ο: CaFe4O7

•: CaSiO3H2Ox: Ca(OH)2

ο•

ο

700°C

•x x

Figure 4-13. XRD patterns of LY2 char (10 wt% of CCA) and LY4 char (10 wt% of CaCO3)

after gasification at 700°C.

84

The high efficiency of EFBA can be explained by using XRD patterns shown in Fig.

4-12. The reason may be attributed that EFBA might be able to generate more effective atom

(K, Na, Ca) than K2CO3 chemical reagent. Therefore, the char conversion is higher than

K2CO3 chemical reagent. In case of CCA, the Ca atom in CaCO3 chemical reagent can absorb

CO2 similar with Ca(OH)2. Therefore, carbon conversion of chemical reagent is similar with

ash as the XRD patterns shown in Fig. 4-13.

4.4 Conclusions

The effects of two different biomasses catalysts including chicken dropping compost

(CC) and empty fruit bunch (EFB) to the performance for the CO2 gasification process

utilizing of Loy Yang brown coal (LY) were investigated. By adding CC ash (CCA) and EFB

ash (EFBA), the CO2 gasification rate and conversion of the LY has increased. The catalytic

activity has shown at the low temperature from 700ºC. Furthermore, the EFBA is more

efficient in increasing the catalytic activities compared to the CCA with the same conditions.

85

References

[1] Higman C, Van der Burgt M. J. Gasification. 2nd ed. New York: Elsevier; 2008.

[2] Wen C Y, Lee E S, Coal conversion technology. Advance book program reading.

Massachusetts: Addison-Wesley Publishing Company; 1979.

[3] Tomaszewicz M, Labojko G, Tomaszewicz G, Michalina K.-M, The kinetics of CO2

gasification of coal chars. J. Thermo. Anal. Calorim. 2013; 113: 1327-1335.

[4] Zhang Y, Ashizawa M, Kajitani S, Hara S, A new approach to catalytic coal

gasification: The recovery and reuse of calcium using biomass derived crude

vinegars. Fuel. 2010; 89: 417-422.

[5] Gomez A, Mahinpey N, Kinetic study of coal steam and CO2 gasification: A new

method to reduce interparticle diffusion. Fuel. 2015; 148: 160-167.

[6] Ding L, Zhou Z, Guo Q, Huo W, Yu G, Catalytic effects of Na2CO3 additive on coal

pyrolysis and gasification. Fuel. 2015; 142: 134-144.

[7] Lili M, Meijun W, Huimin Y, Hongyan Y, Liping C, Catalytic effect of alkali

carbonates on CO2 gasification of Pingshuo coal. Mining Sci. and Tech. (China).

2011; 21: 587-590.

[8] Jiang M Q, Zhou R, Hu J, Wang F C, Wang J, Calcium-promoted catalytic activity

of potassium carbonate for steam gasification of coal char: Influences of calcium

species. Fuel. 2012; 99: 64-71.

[9] Lahigani P, Zainal Z A, Mohamed A R. Catalytic effect of iron species on CO2

gasification reactivity of oil palm shell char. Thermochim. Acta. 2012; 546: 24-31.

[10] Hu J, Liu L, Cui M, Wang J, Calcium-promoted catalytic activity of potassium

carbonate for gasification of coal char: The synergistic effect unrelated to mineral

matter in coal. Fuel. 2013; 111: 628-635.

86

[11] Xiao X, Cao J, Meng X, Le D D, Li L, Ogawa Y, Sato K, Takarada T, Synthesis gas

production from catalytic gasification of waste biomass using nickel-loaded brown

coal char. Fuel. 2013; 103: 135-140.

[12] Kim Y K, Hao L F, Park J I, Miyawaki J, Mochida I, Yoon S H, Catalytic activity

and activation mechanism of potassium carbonate supported on perovskite oxide for

coal char combustion. Fuel. 2012; 94: 516-522.

[13] Mitsuoka K, Hayashi S, Amano H, Kayahara K, Sasaoaka E, Uddin M A,

Gasification of woody biomass char with CO2: The catalytic effects of K and Ca

species on char gasification reactivity. Fuel Process. Technol. 2011; 92: 26-31.

[14] Lahijani P, Zainal Z A, Mohamed A R, Mohammadi M, CO2 gasification reactivity

of biomass char: Catalytic influence of alkali, alkaline earth and transition metal salts.

Bioresour. Technol. 2013; 144: 288-295.

[15] Ochoa1 J, Cassanello M C, Bonelli P R, Cukierman A L, CO2 gasification of

Argentinean coal chars: a kinetic characterization. Fuel Process Technol. 2001; 74:

161-176.

[16] Ohme H, Suzuki T. Mechanisms of CO2 gasification of carbon catalyzed with group

VIII metals. 1. Iron-catalyzed CO2 gasification. Energy Fuels. 1996; 10: 980-987.

[17] Jaffri G R, Zhang J Y, Catalytic gasification of Fujian anthracite in CO2 with black

liquor by thermogravimetry. J. Fuel Chem. and Technol. 2007; 35(2): 129-135.

[18] Aranda G, Grootjes A J, Van der Meijden C M, Van der Drift A, Gupta D F, Sonde

R R, Poojari S, Mitra C B, Conversion of high-ash coal under steam and CO2

gasification conditions. Fuel Proc. Technol. 2016; 141: 16–30.

[19] Kim Y K, Park J I, Jung D W, Miyawaki J, Yoon S H, Mochida I, Low-temperature

catalytic conversion of linite: 1. Steam gasification using potassium carbonate

supported on perovskite oxide. J. Ind and Eng. Chem. 2014; 20: 216-221.

87

[20] Jaffri G R and Zhang J Y, Catalytic activity of the black liquor and calcium mixture

in CO2 gasification of Fujian anthracite. Chin. J. Chem. Eng. 2007; 15(5): 670-679.

[21] Sams D A and Shadman F. Mechanism of potassium-catalyzed carbon/CO2 reaction.

AICHe J. 1986; 32(7): 1132-1137.

[22] Perander M, Demartini N, Brink A, Kramb J, Karlstrom O, Hemming J, Moilanen A,

Konttinen J, Hupa M, Catalytic effect of Ca and K on CO2 gasification of spruce

wood char. Fuel. 2015; 150: 464-472.

[23] Sams D and Shadman F, Catalytic effect of potassium on the rate of char-CO2

gasification. Fuel. 1983; 62: 880-882.

88

Chapter 5

Conclusions

Activated carbon from biomass by pyrolysis with and without catalysts in fixed bed

reactor was studied. The various types of catalysts that contained from nature and chemical

reagent was compared on specific surface area, activated carbon yield, and pore size

distribution. Catalytic gasification from coal also was studied. We have focuses on the

utilizing of Loy Yang brown coal (LY) as natural starting material for CO2 gasification. The

carbon conversion of LY char was catalyzed by using two different biomasses including

chicken dropping compost (CC) and empty fruit bunch (EFB).

In chapter 2, various types of biomasses including teak sawdust (TS), cypress (CP),

bagasse (BG), empty fruity bunch (EFB), and palm kernel shell (PKS) was used to produce

activated carbon. Among various types of catalysts, CaCO3 has higher specific surface area

with lower activated carbon yield compared to Ca(OH)2 and chicken compost (CC). This is

because the pore-blocking effects of Ca atoms and also the carbon content in the CaCO3.

When the catalyst to biomass ratio has increased from 1.0 to 3.0, the SSA of various types of

biomass has increased to 807 to 1082 m2/g. This means, increasing of catalyst in the process

can increases the SSA.

In chapter 3, activated carbons (ACs) can be produced from teak sawdust

(TS) mixed with two different biomass activation agents including chicken dropping compost

ash (CCA) and empty fruit bunch ash (EFBA). The specific surface area (SSA) of ACs over

1000 m2g-1 can be obtained for both CCA and EFBA after physical activation process in

N2/2%CO2 gas ambient at 1000oC. However, the potassium compound (K2O) in EFBA has

more efficiency to increase the SSA compared to the calcium compound (CaO) in CCA.

89

In chapter 4, the effects of two different biomass-derived ash catalysts, chicken dropping

compost ash (CCA) and empty fruit bunch ash (EFBA), on the performance of the CO2

gasification of Loy Yang brown coal (LY) were investigated. By mixing LY with CCA and

EFBA, the CO2 gasification rate and conversion of the LY increased. It was shown that the

catalytic activity starts to become prominent at the temperature of 650°C. Furthermore, the

EFBA is more efficient in increasing the catalytic activity compared to the CCA under the

same conditions.

90

Acknowledgements

Foremost, the author would like to express my sincere gratitude to my principal

supervisor Prof. Takayuki Takarada for his continuous support, study and research, for his

patience, motivation, enthusiasm, immense knowledge and fruitful discussion during my

doctoral course. His guidance helped me in all the time or research and writing of this thesis.

The author was much appreciated and respected to him for given the valuable chance to study

abroad in Japan. The most precious things that I obtained from him during these three years

were the carefully think about the originality of the research work and also the good logic to

organize the thesis and publication story.

Beside my supervisor, the author would like to thanks the rest of my thesis

committees: Prof. Takayuki Ohshima, Prof. Tomohide Watanabe, Prof. Shinji Katsura and

Associate Prof. Reiji Noda for their encouragement, insightful comments, and hard questions

during my intermediate presentation and final thesis defense that are valuable for the future

research work. The author also would like to thanks Osaka Gas Co., Ltd. and JST-MOST

project, Japan for their financial support on this research.

The author would like to thanks all the members of Takarada’s laboratory for their

support, especially Associate Prof. Naokatsu Kannari for discussion during the Doctoral

course. The author would like to appreciate to Mrs. Miyoko Kakuake, Mrs. Mayumi Tanaka,

Mrs. Kumiko Sakamoto and Mrs. Yumi Kojima, the secretariats of Takarada’s laboratory to

support me and taken care about my living in Japan. Furthermore, the author would like to

thanks Mr. Hoshino for his kindly support the financial for the living expenses and take care

for a warmly meeting and party every month.

Last but not least, the author would like to thanks my family: My parents, Mr.

Bumrung Kongsomart and Mrs. Somsri Kongsomart, for giving birth to me at the first place

91

and support me spiritually throughout my life. My older sisters, Mrs. Parada Boonchoowong

and Mrs. Chadasa Klinsukon. Thanks all of my friends and Thai students in Kiryu, Gunma

(Japan) who give me laugh and relax from the stress and pressure during these three years.

Without their support, the goal to achieve the Doctoral degree from Gunma University was

not success.

Boodsakorn Kongsomart

Gunma University, Kiryu, Japan

01 February 2016

92

Publication lists

Journal Publication (2)

[1] B. Kongsomart, L. Li and T. Takarada, “Preparation of activated carbons from teak

sawdust using chicken dropping compost and empty fruit bunch”, International Journal

of Biomass & Renewables, vol. 4 (2), pp. 1–7 (2015).

[2] B. Kongsomart , N. Kannari and T. Takarada, “Catalytic effects of biomass-derived ash

on Loy Yang brown coal gasification”, International Journal of Biomass &

Renewables (In-press).

International conferences (7)

[1] B. Kongsomart and T. Takarada, “Preparation of activated carbon and catalytic coal

gasification using biomass ash”, The 17th International Conference on Clean Coal

Technologies (CCT2015), Poland (2015).

[2] B. Kongsomart, B. Tsedenbal, N. Kannari and T. Takarada, “Preparation of activated

carbon from teak sawdust by using chicken dropping compost ash as an activation

agent”, The 13th China-Japan symposium on coal and C1 chemistry, China (2015).

[3] B. Kongsomart, B. Tsedenbal, N. Kannari and T. Takarada, “Preparation of activated

carbon from teak sawdust with empty fruit bunch ash”, The 13th China-Japan

symposium on coal and C1 chemistry, China (2015).

[4] B. Kongsomart, B. Tsedenbal, S. Komatsu, N. Kannari and T. Takarada, “Low

temperature catalytic gasification of brown coal using chicken droppings”, The 13th

China-Japan symposium on coal and C1 chemistry, China (2015).

93

[5] B. Kongsomart, B. Tsedenbal, S. Komatsu, N. Kannari and T. Takarada, “Low

temperature catalytic gasification of brown coal using empty fruit bunch”, The 13th

China-Japan symposium on coal and C1 chemistry, China (2015).

[6] B. Kongsomart, L. Liuyun, S. Komatsu, N. Kannari and T. Takarada, “Low temperature

catalytic gasification of brown coal using biomass”, The 2015 ICCS&T/ACSE,

Australia (2015).

[7] T. Takarada, B. Kongsomart and B. Tsedenbal, “Low temperature pyrolysis and

gasification of biomass and brown coal using catalysts from natural product”, The 5th

International Conference on the Characterization and Control of Interfaces for

High Quality Advanced Materials and the 51st Summer Symposium on Powder

Technology (ICCCI 2015), DI-13, p. 137, Japan (2015).

Domestic conferences (4)

[1] B. Kongsomart and T. Takarada, “Preparation of activated carbon from biomass using

chicken compost”, The SCEJ 79th Annual Meeting, Japan, J207, p. 625 (2014).

[2] B. Kongsomart and T. Takarada, “Synthesis of activated carbon from biomass using

agricultural waste ash by pyrolysis,” The 23rd Annual Meeting of Japan Institute of

Energy, Japan, 3-7-2. pp. 114-115. (2014).

[3] B. Kongsomart, L. Liuyun, N. Kannari and T. Takarada, “Catalytic CO2 gasification of a

brown coal using biomass ash as a catalyst”, The 24th Annual Meeting of Japan

Institute of Energy, Japan (2015).

[4] B. Kongsomart, N. Kannari and T. Takarada, “Utilization of chicken dropping compost

for activated carbon preparation and catalytic gasification”, The 1st SEOULTECH-GU

Joint Seminar on Cooperation of Politics and Technology (CPT-1), Japan, P-17, p. 61

(2016).

94

Author biography

Boodsakorn Kongsomart was born on February 25th, 1986 in Saraburi (Thailand). She

received the Bachelor of Science (Industrial Chemistry) and Master of Science (Industrial

Chemistry) from Chiang Mai University (CMU), Thailand 2007 and 2012, respectively. She

was an exchange student of Gunma University (Japan) in 2012. Her current research topic

during doctoral course is related to activated carbon and catalytic gasification process.