MSc. thesis Samir Najem Aldeen Khurshid721123/FULLTEXT01.pdf · MSc. thesis Samir Najem Aldeen...
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Biodiesel production by using heterogeneous catalyst MSc. thesis Samir Najem Aldeen Khurshid Division of Chemical Technology Department of Chemical Engineering and Technology Royal Institute of Technology (KTH) Stockholm, Sweden March 2014
Transcript of MSc. thesis Samir Najem Aldeen Khurshid721123/FULLTEXT01.pdf · MSc. thesis Samir Najem Aldeen...
Biodiesel production by using heterogeneous catalyst MSc. thesis
Samir Najem Aldeen Khurshid Division of Chemical Technology Department of Chemical Engineering and Technology Royal Institute of Technology (KTH) Stockholm, Sweden March 2014
Biodiesel production by using heterogeneous catalyst MSc. thesis
Samir Najem Aldeen Khurshid Supervisor Rolando Zanzi Vigouroux Chemical Technology, Chemical Engineering and Technology Royal Institute of Technology (KTH), Stockholm, Sweden Examiner Henrik Kusar Chemical Technology, Chemical Engineering and Technology Royal Institute of Technology (KTH), Stockholm, Sweden March 2014
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ACKNOWLEDGEMENT
This work is dedicated to the soul of my big sister, the person who supported me all the time and learned
me since I was child. She gave me kindness and advice and left me early.
I would like to thank my supervisor PhD Rolando Vigouroux for his support, instruction and direction in
my master thesis in chemical engineering for energy and environment. I thanks also the Associate Professor
Yohannes Kiros for his efforts in laboratory part.
Thanks and gratitude to my mother and father for they gave me discipline in life and supported me wherever
I settle and I am grateful to my wife who is very a considerate person and patient in difficult times.
Thanks and gratitude to my children Yousef and Amir because they brought the happiness to my heart.
Thanks and gratitude to all the teachers who taught me.
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ABSTRACT
Industrial development is associated with an increasing in pollution levels and rising fuel prices. Research
on clean energy contributes in decreasing global warming impacts (significant environmental benefits),
reducing emissions gases. The developing of renewable energies increases the energy independence and
impacts on agriculture in a positive way.
Transesterification reaction of triglycerides to produce fatty acid methyl ester (FAME) was investigated by
using virgin rapeseed oil and doped lithium calcium oxide Li-CaO as a heterogeneous solid basic catalyst.
The influence of different parameters conditions such as the catalyst weight % base oil weight, mass ratio
of methanol to oil, operation time, reaction temperature and mixing intensity on the yield and properties of
the produced biodiesel were studied
The used catalyst and the produced biodiesel were characterized by using techniques of gas chromatography
(GC), X-ray diffraction (XRD), BET surface area measurement (BET) and viscometer.
The results indicate the influence of the various reaction conditions such as molar ratio of methanol to oil,
mass ratio of catalyst to oil and reaction temperature on the on the yield and properties of the obtained
biodiesel yield.
Increasing the temperature under a range lower than methanol boiling point will increase the yield. An
increase of the amount of catalyst from 2.5 wt% to 5 wt% does not increase the amount produced
biodiesel. The yield of produced biodiesel increases with the alcohol to oil ratio.
An amount of 2.5 wt% catalyst is enough catalyst in order to achieve high yield of biodiesel. At alcohol to
oil ratio 6:1 the yield of produced biodiesel increases when the reaction time increases from 1 to 2 hours.
At higher alcohol to ratio (9:1 and 12:1), an increase of reaction time from 1 to 2 hours does not increase
the yield of produced biodiesel. At 60 °C, the yield of obtained biodiesel increase when the mixing rate
increases from 160 to 320 rpm. 97 % yield of biodiesel has been obtained using Li-CaO catalyst using
12:1 molar ratio of methanol to oil , 60°C, 160 rpm mixing rate, catalyst loading 2,5% (base oil weight)
and one hour reaction time.
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TABLE OF CONTENTS
ABSTRACT ................................................................................................................................................................. 3
1. INTRODUCTION ................................................................................................................................................... 7
2. FEEDSTOCK AND PRODUCTS .......................................................................................................................... 8
2.1 Oil ...................................................................................................................................................................... 8
2.2 Alcohol ............................................................................................................................................................. 12
2.2.1 Methanol, MeOH ....................................................................................................................................... 12
2.2.2 Ethanol ...................................................................................................................................................... 13
2.3 Biodiesel .......................................................................................................................................................... 15
2.4 Glycerol ............................................................................................................................................................ 20
2.5 Catalyst ............................................................................................................................................................. 21
2.5.1 Homogeneous Catalyst.............................................................................................................................. 21
2.5.2 Heterogeneous Catalyst ............................................................................................................................ 22
2.5.3 Enzyme Catalyst ........................................................................................................................................ 23
3 KINETIC MODEL ................................................................................................................................................. 23
3.1 Kinetic of transesterification reaction ............................................................................................................. 23
3.2 Mechanism of Reaction ................................................................................................................................... 27
4 ANALYSIS EQUIPMENTS .................................................................................................................................. 33
4.1 Gas Chromatography (GC) .............................................................................................................................. 33
4.2 Brunauer, Emmett and Teller (BET) ................................................................................................................ 34
4.3 Viscosity measurement .................................................................................................................................... 36
4.4 X-Ray diffraction ........................................................................................................................................... 38
5 - EXPERIMENTAL SETUP CONDITIONS ......................................................................................................... 42
5.1 Catalyst preparing : .......................................................................................................................................... 42
5.2 Reaction and Retention time ............................................................................................................................ 43
5.3 Calculations ...................................................................................................................................................... 45
6 - RESULTS and DISCUSION ................................................................................................................................ 46
6.1 Temperature Influence .................................................................................................................................... 46
6.2 Amount catalyst .............................................................................................................................................. 47
6.3 Mixing rate ..................................................................................................................................................... 48
6.4 Alcohol to oil ratio .......................................................................................................................................... 49
6.5 Reaction time .................................................................................................................................................. 50
6.6 Waste cooking oil ............................................................................................................................................ 51
6.7 Conversion vs. reaction time ........................................................................................................................... 52
6.8 Accuracy and Error of results ........................................................................................................................... 53
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7- CONCLUSION ...................................................................................................................................................... 54
8- REFERENCES ...................................................................................................................................................... 55
List of tables
Table 1: Composition of rapeseed oil .......................................................................................................................... 8
Table 2: Oil Composition of various edible oil. .......................................................................................................... 9
Table 3: Biodiesel and feedstock generation ............................................................................................................. 10
Table 4: Biodiesel properties form different oil sources compared to petroleum derived diesel ............................ 11
Table 5: Comparison of Fuel Properties ................................................................................................................... 12
Table 6: Ethanol and petrol physical properties ........................................................................................................ 13
Table 7: Ethanol generation type .............................................................................................................................. 14
Table 8: Comparison between petrodiesel and biodiesel properties .......................................................................... 15
Table 9: Properties of the obtained biodiesel and the standards of biodiesel in the United States and Europe ......... 19
Table 10: Advantage and Disadvantage of biodiesel and fossil Diesel [65-67] ....................................................... 19
Table 11. Different catalysts used in transesterification of different oils .................................................................. 23
Table 12: Stoichiometry of the transesterification reaction for biodiesel production .............................................. 24
Table 13: GC operation setup.................................................................................................................................... 34
Table 14: BET surface Area Report .......................................................................................................................... 35
Table 15: Influence of lithium amount on the CaO surface area .............................................................................. 36
Table 16: Density of different glycerol mixture and temperature [27] ..................................................................... 37
Table 17 Absolut viscosity of different glycerol mixture and temperature [28] ...................................................... 38
Table 18: Samples tested in XRD analysis: .............................................................................................................. 39
Table 19: XDR setting .............................................................................................................................................. 41
Table 20: Molecular weights for catalyst feedstock .................................................................................................. 42
Table 21: Biodiesel yield by using Li/CaO with different feedstock [90, 91 ] ......................................................... 43
Table 22: Triglycerides conversion vs. FAME yield% ............................................................................................. 53
Table 23 samples viscosities ..................................................................................................................................... 61
Table 24: Experimental Result ................................................................................................................................... 62
Table 25 Experimental Result ................................................................................................................................... 63
List of figures
Figure 1: MEOH environmental production process ................................................................................................ 12
Figure 2: Ethanol production process ........................................................................................................................ 14
Figure 3: EU-biodiesel production (tons) [47] .......................................................................................................... 16
Figure 4 shows the alkali-catalyzed process of biodiesel production. ....................................................................... 16
Figure 5: Process flow chart of alkali-catalyzed biodiesel production ...................................................................... 17
Figure 6: Monthly Prices Received by US Farmers Since 1990 ............................................................................... 18
Figure 7: United State Annul Biodiesel production and consumption ...................................................................... 18
Figure 8: Flow chart for biodiesel and glycerol production ...................................................................................... 20
Figure 9: Flow chart for Biodiesel production .......................................................................................................... 22
Figure 10: Particle Catalyst Surface .......................................................................................................................... 25
Figure 11: LH Mechanism for transesterification of triglycerides with Alcohol [33] .............................................. 29
Figure 12: Eley-Rideal (ER) mechanism of (a) Brønsted acid and (b) Lewis solid acid catalysts ........................... 30
Figure 13: Steps in a Heterogeneous Catalyst Reaction ........................................................................................... 31
Figure 14: Reaction rate vs. the ratio of velocity to particle size ............................................................................... 32
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Figure 15: Catalyst boundary layer ............................................................................................................................ 32
Figure 16 GC ......................................................................................................................................................... 33
Figure 17: BET ........................................................................................................................................................... 35
Figure 18 a. BET surface area , b. catalyst pore volume ........................................................................................... 35
Figure 19 Viscosimeter ............................................................................................................................................. 36
Figure 20: XRD ......................................................................................................................................................... 39
Figure 21: sample A. Li-CaO Catalyst XRD Analysis ............................................................................................. 40
Figure 22: Experimental operation system ............................................................................................................... 44
Figure 23: graduated cylinder .................................................................................................................................... 44
Figure 24: Effect of temperature on FAME yield. .................................................................................................... 46
Figure 25: Effect of temperature on FAME yield. ................................................................................................... 47
Figure 26: Effect of Catalyst % on FAME yield. ..................................................................................................... 48
Figure 27: Effect of mixing intensity on FAME yield. ............................................................................................ 48
Figure 28: External resistance to mass transfer [ 26 ] ............................................................................................... 49
Figure 29: Effect of methanol-oil mole ratio on FAME yield................................................................................... 49
Figure 30: Effect of methanol-oil mole ration on FAME yield................................................................................. 50
Figure 31: Effect of Reaction time on FAME yield .................................................................................................. 51
Figure 32: Effect of Reaction time on FAME yield .................................................................................................. 51
Figure 33: Yield of produced biodiesel vs temperature. Waste cooking oil. ............................................................. 52
Figure 34: Triglycerides conversion vs. FAME yield% ............................................................................................ 53
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1. INTRODUCTION
In the last decade, the world has witnessed many changes in the energy field where many companies around
the world created new strategies based on reducing the environmental impact and achieving competitive
prices of biofuel compared with fossil fuel.
The new form of energy has several features. It requires lower cost of infrastructure and lower
environmental impact since it will replace a big share of demand to fossil fuel. In addition it reduces effects
of greenhouse gases due to less SOx, NOx and CO2 gases emissions compared with fossil fuel production.
At the same time the capability to produce it from different raw agriculture material, edible and non-edible
oil is increasing. However it is less than expected due to bad weather, drought affect and growth of global
population which tend to increase global grain prices as occurred in 2012 that leads to raise a big question
about which is more important, food or biofuel [1][2].
Today biodiesel compared with petroleum is considered an environmentally friendly fuel due to low carbon
dioxide emissions, biodegradable fuel, high cetane number, high combustion efficiency, lower aromatic
and sulphur content in comparison to petroleum diesel, making the biodiesel a competitive fuel in the mar-
ket [3-5].
Biodiesel production aims to get good qualities and quantities by choosing suitable and cheap feedstock
such as virgin vegetable oils, used cook oils and animals fats. A good raw oil for biodiesel production low
least fatty acid content. In the study, rapeseed oil (a virgin oil) is used for biodiesel production. Other types
of edible vegetable oil can be used for instance; soybean oil, sunflower, palm oil, canola and peanut oil or
even non-edible oils such as sea mango, jatropha, rubber seed and pongamia pinnata [6].
The main structure of biodiesel consists of triglyceride molecules of three fatty acids. It has ester bonding
to a single molecule of glycerol. The fatty acid has different lengths of chain depends on their number of
carbon.
Biodiesel is produced through esterification and transesterification reactions of vegetable oil and animal
fats with an alcohol. Methanol or ethanol are usually the alcohol for biodiesel preparation. The reaction is
facilitated with a suitable catalyst either homogeneous or heterogeneous. The amount of free fatty acid is
import in order to select the appropriate catalyst [7] [82].
The competition of producing biodiesel related with raw materials cost is high since the production process
uses edible oil. Moreover, the conflict on food prices is currently high. For these reasons, the use of cheap
non-edible vegetable oils or waste cooking oils decreases the cost of the raw materials.
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Unfortunately, a significant free fatty acid content reduces catalyst activity which leads to reduce biodiesel
yield. Moreover, the produced biodiesel is required to undergo an efficient purification [8] [9].
Transesterification by acid-catalysed is one of the best method dealing with free fatty acid in spite of it has
a relatively slow reaction rate [10]. It can be a promising method for biodiesel production using oils with
high FFA content if it is combined with an alkali-catalysed transesterification [11- 14,70-71].
Lithium a dope calcium oxide particles exhibits a high activity for TG conversion. Table 1 illustrates the
composition of rapeseed oil. Oleic acid (61.5%) is the biggest component in Rapeseed Oil [41].
Table 1: Composition of rapeseed oil
Palmitic acid Estearic acid Oleic acid Linolenic acid Linoleic acid
C16H32O2 C18H36O2 C18H34O2 C18H30O2 C18H32O2
Percentage % 5.3 2.1 61.5 9.1 20.5
Molecular weight
(g/mol)
256 284 282 278 280
2. FEEDSTOCK AND PRODUCTS
2.1 Oil
Rapeseed oil is an extract from Brassica Napus. It is one of the cruciferous plant family (cabbage family)
used as a raw material for biodiesel production. Today it is considered as one of the most important crop in
Europe due to its oil content importance 40–45% [15].
Many types of edible vegetable oils like rapeseed, corn, canola and soybean are used as biofuel. They act
as good diesel substitutes [16] [17]. But the high viscosity and high molecular mass of triglycerides affect
directly the biofuel quality. It causes incomplete combustion, high carbon deposits and injection nozzle
problems. In addition, it causes high pour point of biodiesel.
Fluid dynamics are influenced by the cold weather, therefore it is necessary to improve fluid (Oil) physical
properties to become similar to diesel characteristics through transesterification or pyrolysis modification
[18].
For the current time, transesterification of triglycerides with alcohol is more favourable than pyrolysis
method due to some unacceptable physical properties of biodiesel produced by pyrolysis, for instance high
cetane number, an accepted amount of copper, sulphur and water, low viscosity product and high
requirement of high temperature for operation which is approximately 500C [19][74].
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The waste cooking oil requires pre-treatment before transesterification reaction. Waste cooking oil contains
high amounts of free fatty acids which need to be removed. Some pretreatment method for waste cooking
oils are steam injection, column chromatography, neutralization, film vacuum evaporation and vacuum
filtration. But these pretreatment methods make the process less efficient and more complicated. A usual
method to treat the waste cooking oils is the esterification of FFA with sulphuric acid acting as catalyst.
Both the homogenous and heterogeneous acid catalysts can be used in this method [20].
Table 2 shows the composition of various edible and non-edible oils [2, 9].
Table 2: Oil Composition of various edible oil.
Fatty acids
Oleic
linoleic
Palmitic
Stearic
Linolenic
Palmitoleic
other
Rapeseed
55.68
17.82
4.12
1.57
7.61
0.05
13.15
Palm
40
10
45
5
-
-
-
Soybean
23
51
10
4
7
-
-
Jatropha
43.1
34.3
14.2
6.9
-
-
14
Pongamia
pinnata
71.3
18.3
7.9
8.9
-
-
-
Rubber
Seed
24.6
39.6
10.2
8.7
16.3
-
-
Biofuel and its feedstock are classified into different generation order as shown in table 3 [21, 22].
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Table 3: Biodiesel and feedstock generation
Generation Produced
material Based on Limitation
First
Biodiesel
Agricultural feedstock , e.g. cane,
oil extracts from plants
Conflicts between fuel pro-
duction, graze land for cattle
and food production.
Second
Biodiesel
Methanol
Chemical conversion of biomass gasification of forest residues and
black liquor for the production of
hydrogen, methanol /DME.
Conflicts with the
forest industry. Biomass insufficient for fuel
production
Third
Fully syn-
thetic e.g.
methanol
Renewable sources such as
solar, hydro power, wind power
Limited efficiency
According to the table 3, biodiesel is produced from first and second generation processes while methanol
is produced from second and third generations. The biggest limitations to biodiesel production are the food
conflict, the vegetable oils prices and graze land for cattle while methanol production faces conflict with
the forest, in addition, biomass is not enough to cover the demand for biofuel
Rapeseed oil is the oil used in this study with Li-CAO acting as heterogeneous catalyst. The biodiesel
produced from rapeseed oil has viscosity 4.5 cSt at 40 °C higher than petroleum diesel (2.6 cSt).
The biodiesel produced from rapeseed oil has a pour point of -12 °C and it has a heating value of 170 MJ/kg
as shown in table 4 where the physical and chemical properties of biodiesel from different oil sources are
compared to petroleum derived diesel [64].
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Table 4: Biodiesel properties form different oil sources compared to petroleum derived diesel
Non-Edible Oil
Specie
Viscosity cSt, 40°C
Density g/𝑐𝑚3
Specific gravity
Pour point
𝐶0
Flash point 𝐶0t
Acid Value Mg KOH/g
Heating value MJ/kg, LHV
Jatropha curcas
4.800
0.92
-
2
135
0.4
38.5
Sea mango
29.57
0.92
-
-
-
20
40.86
Palanga
72
0.9
221
44
39.25
Rubber seed
5.81
0.874
-
130
0.118
Edible Oil
Rapeseed oil
4.50
-
0.882
-12
170
-
-
soybean
4.08
0.885
-3
69
-
-
Palm
4.42
0.9
15
182
0.08
sunflower
32.6
0.92
274
0.15
39.6
Petroleum Diesel
Petroleum Diesel
2.6
-
0.850
-20
68
-
-
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2.2 Alcohol
2.2.1 Methanol, MeOH
MeOH is a basic alcohol used in excess in transesterification of triglycerides to produce biodiesel fuel at a
present of catalyst and it is known as methyl alcohol and wood alcohol and abbreviated as MeOH. MeOH
is light, volatile and colourless. MeOH is consider as a safe fuel. However, it is in fact flammable and burns
with an invisible flame and it is biodegradable quickly when compared with petroleum fuels. The
differences between them are shown in table 5.
MeOH is a polar liquid at ambient temperature (25C), in spite of his ability of attracting water molecular
in stored case, it still has bad solubility in water and petrol or organic compounds [44].
Table 5: Comparison of Fuel Properties
Property Density at 20°C LHV (MJ/Kg) Octane number Fuel eqv. GHG[ gCO2 eq/MJ ]
Methanol
0.79
19.7
> 110
0.48
Waste wood
methanol : 5
Farm wood
methanol:7
Petrol 0.74 43.9 92 1
Industrial Methanol is synthesized mainly from natural gas and coal as in China and South Africa. It is
considered as renewable fuel when it is produced by using a conversion biomass through thermochemical
or biotechnological processes.
In fact it is required essential pre-treatment methods for the raw materials such as drying mechanical cutting
as it is shown in Fig.1:
Figure 1: MEOH environmental production process
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Methanol is used for synthesis of different types of industrial products e.g. formaldehyde, acetic acid,
olefins and DME (an environmentally friendly alternative to diesel oil) which are used in transport segment.
Methanol is used directly as a petrol by mixing it with some chemicals or using it as synthesis petrol
additives like MTBE/TAME.
The production MeOH in the world reached in 2007 to 40 million tons. The German company Choren
Industries is producing methanol from wood since 2004 using the Carbo-V process. In Sweden about 6
tons per day of methanol have been used as an intermediate in the production of Bio DME with investment
about 14 million EUR in the Chemrec AB pilot plant in Piteå [45].
2.2.2 Ethanol
Ethanol is abbreviated as EtOH and it is defined as ethyl alcohol. It is a pure, grain alcohol or drinking
alcohol. EtOH physical properties are light alcohol, volatile and flammable liquid. It burns with an almost
invisible flame. It is colourless and biodegradable. It has characteristic odour. EtOH attracts water while
storing. EtOH forms with water an azeotropic mixture [46]. Ethanol is different in physical properties than
petrol as it is shown in table 6.
Table 6: Ethanol and petrol physical properties
Property Density (20°C) LHV (MJ/Kg) Octane
number
Fuel eqv. GHG[ g CO2 eq /MJ]
Ethanol
0.79
26.7
> 100
0.65
Sugar beet ethanol : 33
Farmed wood ethanol: 20
Wheat straw ethanol .11
Petrol 0.74 43.9 92 1
First generation ethanol is produced from sugar and/or starch from food crops such as wheat, corn, sugar
beet and sugar cane. Cellulosic ethanol is second generation ethanol and it is produced from lignocellulosic
biomass such as agricultural residues (straw, corn stover), wood chips or energy crops (miscanthus,
switchgrass).
The fermentation of sugar for ethanol production is represented by the reaction:
C6H12O6 = 2 C2H5OH + 2 CO2
The process takes place in the presence or obscene of Oxygen. The process consumes energy through the
distillation unit used to obtain high pure EtOH. It is still a complicated process due to adapted yeasts re-
quirement, chipping, pre hydrolysis and hydrolysis requirements as it is shown in Fig.2 [47].
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Figure 2: Ethanol production process
It is reasonable to think that cellulosic ethanol will become increasingly important on the biofuel market as
shown in table 7 [47].
Table 7: Ethanol generation type
Generation type Feedstock Feature
First generation of
EtOH
Based on agricultural feedstock e.g.
sugar cane oil extracts from plants and
grain.
Have limited Feedstock potential
The energy efficiency is low in LCA
perspective.
Increased conflicts between fuel
production, graze land food
production
Second generation of
EtOH
a. Cellulosic ethanol
b. Based on chemical conversion of
biomass e.g. gasification of black
liquor for the production of
hydrogen or forest residues
More sustainable
Biomass insufficient for fuel
production
Conflicts with the forest industry.
Industrial processes efficiency can reach 90 to 95 % of theoretical yields but the composition of biomass
must be modified to break down the cellulose and hemicellulose at first into fermentable sugars and lignin.
Currently, the conventional spark-ignition engines without technical changes can operate with low
percentage ethanol to gasoline blends (E5, E10). Modern flexi-fuel vehicles can use high ethanol content
blends such as 85% EtOH (E85).
15
Global bioethanol production reached 84.6 Bl. in 2011. 62% was produced in the United States, 25% was
produced in Brazil and 4.6% was produced in the EU.
The use of methanol in biodiesel production is favourable due to the simplification of the glycerol
separation from the final products. The use of ethanol in the production of biodiesel requires a low water
content in both the alcohol and the oils in order to obtain efficient glycerol separation.
2.3 Biodiesel
Biodiesel is a renewable fuel, non-toxic and biodegradable. It is a good alternative for conventional fossil
diesel fuel since it has similar properties as shown in table 8. However, it requires the use of additives to be
suitable for motor fuel in order to overcome oxidation processes limitations [48].
Currently, the main holdback for commercial biodiesel is the high cost of production, usually over US$0.5/l,
compared to US$0.35/l for petroleum based diesel [84].
Table 8: Comparison between petrodiesel and biodiesel properties
Density at
20°C
Viscosity at 20°C
(m𝑚2/s)
Cetane
number
LHV
(MJ/Kg)
Fuel eqv.
FAME 0.88 7.5 56 37.1 0.91
DIESEL 0.83 5.0 50 43.1 1
The essential feedstock for FAME production through transesterification process (reversible reaction) are
vegetable oils and animal fats. It is also used waste cooking oils as raw materials for more environmental
and economic aspects. The reaction uses to be carried out in batch reactor provided with controlled heating
and mixing system.
Triglycerides react with excess methanol using a strong base or strong acid as a catalyst (sodium or
potassium in industrial scale) to produces FAME and glycerol:
16
Because of the low established cost and running cost of biodiesel production, it is considered very promising
to establish small installations of biofuel production. Biodiesel has been produced in EU since 1992, Fig 3.
The EU annual production is up to 6,100,000 tones with about 120 production plants. Austria, Germany,
Italy, France and Sweden are the main producers of biodiesel in EU [51].
The use of 1 kg biodiesel leads to a reduction of about 3 kg of CO2 emissions. Therefore, the use of biodiesel
leads to a significant reduction in CO2 emission from 65% to 90% less compared with the use of
conventional diesel.
Figure 3: EU-biodiesel production (tons) [47]
Direct use of the oil causes poor fuel atomization in injection, gum formation, deposition of coke in engine,
oxidation and polymerization of fatty acids due to the high viscosity of the oil. The combustion efficiency
decreases because of insufficient mixing of the fuel with air leading to higher emission of hydrocarbons.
By producing biodiesel the physical properties of the oils are enhanced making the biodiesel a reliable, safe
fuel to use for diesel engines. The biodiesel uses to be blended with conventional diesel in different
percentage. The biodiesel production requires pretreatment for feedstock oils in order to reduce the free
fatty acid content under 2,5wt%.
Figure 4 shows the alkali-catalysed process of biodiesel production.
The alkali homogeneous catalysed process of biodiesel production is more economic today the process
using heterogeneous or enzymatic catalysts [7] [43].
17
Figure 5: Process flow chart of alkali-catalysed biodiesel production
The production process can occur in the following steps:
1. Mixing of alcohol and catalyst: The catalyst is normally sodium hydroxide or potassium hydroxide which dis-
solves in the alcohol by using a standard agitator or mixer during the reaction. The alcohol and catalyst mix then
charge into a closed reaction vessel and the oil or fat is added.
2. Separation: In this section glycerine and biodiesel are separated. The reacted mixture is sometimes neutralized
at this step.
3. Alcohol removal. The excess alcohol in each phase can be removed with a flash evaporation process or by dis-
tillation since the glycerine and biodiesel phases have been separated.
4. Glycerine Neutralization. The glycerine by-product contains often unused catalyst and soaps that are neutral-
ized by adding an acid and sent lately to storage for crude glycerine. The glycerine can be used for preparation
of cosmetics and medicine [43].
5. Methyl Ester Wash. The biodiesel purifies by washing with warm water to remove residual catalyst or soaps
after separating from the glycerine
6. Product Quality.
The finished biodiesel must be analysed to ensure it meets any required specifications. The most important
aspects of biodiesel production:
Complete Reaction
Removal of Glycerine
Removal of Catalyst
18
Removal of Alcohol
Absence of Free Fatty Acids
In the U.S. and other countries, biodiesel cost is influence by the type of used feedstock. Figure 5 shows
the price of biodiesel produced from wheat, maize and soybeans [63].
Figure 6: Monthly Prices Received by US Farmers Since 1990
In fact the increase competition with food can be solved by using waste cooking oil. But the production of
biodiesel using waste cooking oil is more complicated because of the high FFA content in waste cooking
oils.
A common process is to pretreat the waste cooking oil performing esterification with acidic catalyst (e.g.
sulphuric acid). Then a base catalysts can be used for the transesterification and production of biodiesel.
The United State Annul Biodiesel production and consumption is shown in Fig.6 [63] [72]. At present the
amount produced biodiesel is at the same range of the consumption rate. In July 2013 the average cost of
one gallon biodiesel, B20, was 3,891 $ lower than the cost of petrodiesel which was 3.91$ [65].
Figure 7: United State Annul Biodiesel production and consumption
2000 2005 2010 2015
0
200
400
600
800
1000
1200
yearMill
ion
Gal
lon
s
Consumption
Production
19
Biodiesel fuel is used pure or blended with fossil diesel fuel in transport section and district heating. In
table 9 the properties of biodiesel concerning ester content, free glycerol, total glycerol, density, flash point,
sulphur content, kinematic viscosity, copper corrosion, cetane number, iodine value, and acid value are
shown [90]. In table 10 some advantages and disadvantages of the biodiesel are listed.
Table 9: Properties of the obtained biodiesel and the standards of biodiesel in the United States and Europe
Property Value EN 14214 ASTM D-6751
Density at 15 °C, kg/m3 889 860–900
Free glycerol ,wt.% 0.008 <0.02
Total glycerol, wt.% 0.12 <0.24
kinematic viscosity at 40 °C, cSt 4.1 3.5–5.0 1.9-6.0
Esters content, wt.% 98.1 >96.5
Flash point, °C 161 >120 >130
Sulphur content, mg/kg 2.4 10 15
Iodine number , g I2/100 g 115 < 120
Copper corrosion 1A Class 1 NO. 3max
Cetane number 54 >51 >47
Acid value , mg KOH/g 0.10 <0.5
Table 10: Advantage and Disadvantage of biodiesel and fossil Diesel [65-67]
Advantage and disadvantage
Biodiesel
Nontoxic material, Better lubrication.
Renewable.
No greenhouse gasses emission, Biodegradable
Safe storage due to high flash point.
High cetane number which increase combustion efficiency.
Require anti freezing additive in cold weather due to its higher density.
Fossil Diesel
Toxic.
Lower lubrication, Not renewable.
Greenhouse gasses emission e.g. CO2, NOx , SOx.
Low flash point.
Low cetane number.
Require less amount of anti-freezing additive in cold weather due to its lower density.
20
2.4 Glycerol
Glycerol is a product of the transesterification reaction. It is characterized as colourless liquid. The
molecular formula is C3H8O3. Glycerol has a viscosity of 1.412 Pa*s and a boiling point of 290 °C [4]
[50].
It is used in different applications such as food industry, pharmaceutical, botanical extracts, chemical
intermediate, and antifreeze. It is used as substrate for anaerobic digestion and also in personal care
applications and cosmetic industries.
A large scale of glycerol is produced by esterification of triglycerides. The purification process of crude
glycerol product is expensive. The crude glycerol produced from hydrolysis of triglycerides required
different purification treatments. Activated carbon can be used to remove organic impurities. Unreacted
glycerol esters can be removed by alkali treatment. Salts in glycerol can be removed by ion exchange. By
treatment in multi-step distillation a high purity glycerol (> 99.5%) can be obtained. Figure 7 shows the
production of biodiesel including glycerol purification [47].
A fraction of glycerol uses to be burned in order recovery energy in spite of its LHV [5]. The purification
processes are expensive. The quality of the produced glycerol is variable. The selling price is low (1–8
U.S.cents / Ibm in 2011) [47, 49].
Figure 8: Flow chart for biodiesel and glycerol production
21
2.5 Catalyst
Currently three types of catalyst are used for biodiesel production homogenous, heterogeneous and
enzymatic. Different factors interact in choosing the catalyst, for instance: catalyst thermal stability,
deactivation and conversion rate [86].
2.5.1 Homogeneous Catalyst
Significant amounts of work have been carried out on homogeneous acid and base catalysis transesterification of
vegetable oils. Most of the biodiesel produced today is obtained with the base catalysed reaction for several reasons:
It is a low temperature and low-pressure reaction. It yields high conversion (98%) with minimal side reactions and
short reaction time. It is a direct conversion to biodiesel with no intermediate compounds. Biodiesel production from
feed stocks with high FFA (free fatty acids) is extremely difficult using alkaline catalysed transesterification. The
alkaline catalysts react with FFAs to form soap that prevents the separation of the glycerine and ester. Sulphuric acid
and hydrochloric acid are normally used as acid catalysts especially when the oil contains high amount of free fatty
acids and water.
In the two-step method a pre-esterification operation is applied to eliminate free fatty acids (FFAs) by reacting the
oil with alcohol in the presence of an acid catalyst. The purified oil was further reacted with alcohol in the presence
of an alkali catalyst.
Waste Cooking Oils and Jatropha oils use to have high concentration of free fatty acids.
The desired products of the reaction are the methyl or ethyl esters of the fatty acids initially contained in the fat or
oil. Glycerine and alkali salts (using alkaline esterification) are also obtained as by-products, which may be used as
raw materials in the chemical industry. Glycerine may be used in the pharmaceutical industry. The potassium salts
are used for production of potassium fertilizer.
One of the major disadvantages of homogeneous catalysts is that they cannot be reused or regenerated, because the
catalyst is consumed in the reaction and separation of catalyst from products is difficult and requires more equipment
which could result in higher production costs.
Homogeneous acid catalyst can be used with high-FFA feedstocks. The water has to be removed during
processing. Increasing water concentrations decrease the yield of obtained biodiesel. High temperatures
above 100 °C at moderate pressures and with continuous flow of an inert gas such as nitrogen are used in
order to remove water driving the reaction to high conversion.
Homogeneous acid catalyst has lower reaction rate than homogeneous alkaline requiring higher
temperatures and much excess of alcohol. Liquid acids are also associated with corrosion and
environmental problems [47, 52-55]...
Figure8 shows the industrial production of biodiesel.
22
Figure 9: Flow chart for Biodiesel production
2.5.2 Heterogeneous Catalyst
Heterogeneous catalysts can be separated from final product by filtration and reused. This causes less
consumption of both chemicals and time of course.
Heterogeneous catalysts are noncorrosive. They have a high selectivity and can be easily separated from
the products. Both basic solids such as metal oxides (CaO) and zeolites as well acid solid such as sulphated
tin oxide are used. The use of catalyst supports such as alumina, silica, zirconia and zinc oxide in order to
improve the mass transfer limitation of the three phase reaction will be included. Examples of
heterogeneous catalyst are; La2O3, SrO, BaO KNO3, KF, CaO, CaCO3. Table 11 shows some heterogeneous
catalysts used with different feedstock.
Mass transfer limitations in heterogeneous catalyst due to two phase zone (solid – Liquid) requires well
mixing efficiency in order to reduce the external limitations. It uses to be operated at high temperature and
high alcohol - oil mole ratio. Overcome on diffusion limitation shifts the equilibrium towards products.
Many features of acidic heterogeneous catalyst are suitable for biodiesel production, for instance
insensitivity for water content and free fatty acid content. Heterogeneous catalyst can be used in batch or
continues system. Acid catalysts are more expensive than alkali heterogeneous catalysts. They have also
less active site, therefore, they are more affected by adsorption reactants rate, surface reaction rate,
desorption product rate resulting in limiting biodiesel yield [53-58, 73, 85].
Currently, among the alkaline earth metal oxides, CaO is the most widely used for transesterification with
high yield (98% during the first cycle of reaction) [83]. Modified CaO catalyst with doped lithium increases
23
biodiesel yield since the lithium improves catalyst surface basicity and enhances calcium glyceroxide
formation.
Table 11. Different catalysts used in transesterification of different oils
Oils Rapeseed Soybean Sunflower Palm Jatropha
curcas
Catalyst Mg-Al HT WO3/ZrO2 CaO,SrO ETS-10 MgO, ZnO.
Al2O3
CaO / SBA-14 Mg-
Al.CO3
CaO
Yield 90.5 90 95 94,6 82
95 86.6 93
2.5.3 Enzyme Catalyst
In the last years research has been focused on use of an enzymatic catalyst for production of biodiesel. Lipases used
in biotechnology are normally of microbial origin and produced by fermentation processes. The use of lipases makes
the reaction less sensitive to high free fatty acid (FFA) content which is a problem with the standard biodiesel process.
A number of commercial lipases are available for applied biocatalysis. Whilst some are employed as free powders
the majority are used as immobilised preparations.
Enzyme catalysts have high selectivity and have approximately fixed running cost and reliable capital
investment. It consumes low energy since it operates at low temperature and pressure with one or two steps
of isolated enzymes and no side reactions (saponification) compared with alkali esterification.
It is insensitive to water content. Enzymatic reaction has low reaction rate and the enzyme has high cost
and less activity which is considered as drawback affecting the economic benefit of the process. The
produced glycerol covers the enzyme and reduces its efficiency, therefore, it is required additives to observe
and remove the glycerol such as silica gel [53-62].
3 KINETIC MODEL
3.1 Kinetic of transesterification reaction
Biodiesel is produced by a chemical a reversible chemical reaction of three mole of alcohol methanol with
one mole triglycerides (TG) to produce one mole glycerol and three moles of FAME:
A (TG ) + 3B (MeOH) = C (Glycerol) + 3D (FAME)
24
The reaction as shown down is reversible, it takes place at three different steps which starts with
triglycerides conversion to dig-glycerides and FAME follows by the second and third steps to produce
mono glyceride and glycerol respectively and FAME [68].
Triglyceride + R´H3OH ↔ diglyceride + FAME
Diglyceride + R´H3OH ↔ monoglyceride + FAME
Monoglyceride + R´H3OH ↔ glycerol + FAME
The reaction runs with excess methanol to shift the equilibrium to the forward direction. Table 12 shows
the stoichiometry of the transesterification reaction [26]
Table 12: Stoichiometry of the transesterification reaction for biodiesel production
species Symbol Initial mole Change Remaining
TG A NA0=1 -NA0X NA=NA0(1-X)
MEOH B NB0=3NA0 -3NA0X NB=3NA0(1-X)
Glycerol C NC0= 0 +NA0 NC=NA0X
FAME D ND0= 0 +3NA0 ND=3NA0X
The rate of the reaction is influenced by internal and external diffusion, adsorption and desorption and the
surface reaction rate.
The overall rate of transesterification reaction can be written if form of TG conversion. It is applied the
design equation combined with the mass balance of the reactants and the products depending on a basic
material (limiting material):
Design equation : dx/dt= rA .V/ NA0
Rate equation : rA= K1(CA.CB – CC.CD/Kc)
At equilibrium : Kc= CC.CD/ CA.CB
: K1=K . EXP(-E/RT)
where K= pre exponential factor, E = Activity energy , T= reaction temperature
25
Stoichiometry : NA= NA0(1-X) NA0 = CA0.V NA= CA.V
Combining : dx/dt = K . EXP(-E/RT) (CA.CB – CC.CD/Kc) . V/ NA0
dx/dt = K .EXP(-E/RT) [(NA.NB – NC.ND/Kc) / NA0 ]
dx/dt = K .EXP(-E/RT) [(NA0(1-X).3NA0(1-X) – 3NA0X. NA0X /Kc) / NA0]
dx/dt = 3K/Kc . EXP(-E/RT) [ (1-X)2 – X2]
ʃ dX
[(1−X)^2– X^2] = 3K/Kc . EXP(-E/RT) ʃ dt
Generally, an excess methanol is required in order to shift equilibrium for further increasing of biodiesel
yield.
The probable assumption for catalyst behaviour is a single site, Eley-Rideal (ER). The reaction takes
place at the active site of the catalyst (fig. 10) [26]. According to this assumption, the activity of the cata-
lyst is promoted by increasing the number of basic sites of the catalyst or enlarging the surface area of the
catalysts
Figure 10: Particle Catalyst Surface
The rate of adsorption can be calculated by assuming that it has only effected of the methanol diffusion on
the active sites of the catalyst:
B + S = B . S (1) where B = alcohol
S = catalyst site
26
B.S = adsorbed alcohol on catalyst surface.
[NB]= YB CB [N0] (2) Where [NB] = alcohol concentration at the surface
YB = adsorption coefficient
CB = concentration of alcohol
[N0] = fraction of empty catalyst sites.
The rate of reaction on catalyst surface is calculated from the adsorbed alcohol when it reacts with TG in
liquid phase:
where B.S = adsorbed alcohol at catalyst surface
G = triglycerides = di glycerides =monoglycerides = Oil
M = adsorbed diglycerides or monoglycerides
F = produced FAME
So, the rate of surface reaction:
ra = k1 [NB] CG – k2 [NM] CF (4)
The rate of desorption of products (di glycerides or mono glycerides) is calculated from:
MS=M + S (5)
[NM] = YM CM [N0] (6)
Substituting equation 6 and 2 in equation 4, it is:
27
ra = k1 YB CB [N0].CG – k2 YM CM [N0] CF (7)
The total number of catalyst site, Ns, is the sum of the number of empty catalyst sites [N0], the sites with
alcohol at the surface [NB] and the sites with adsorbed diglycerides or mono glycerides [NM]
[NS] = [N0] + [NB] + [NM] (8)
Substitute equation 6 and 2 in equation 8
[NS] = [N0] + YB CB[N0] + YM CM [N0]
[N0]= NS
1+YB CB+YM CM (9)
Substitute eq (9) in equation 7
ra = k1 YB CB NS
1+YB CB +YM CM CG – k2 YM CM .
NS
1+YB CB+YM CM CF (10)
ra = [ k1 YB CB CG – k2 YM CM CF ] [NS
1+YB CB+YM CM ]
The rate of adsorption will be neglected in case it is much lower than bulk concentration.
YB CB ≫ YM CM.
YM CM = 0
3.2 Mechanism of Reaction
Reactions mechanism and kinetic are important to design a suitable and effective catalyst material under
the biodiesel reaction conditions. Biodiesel production depends on many factors such as, vegetable oil qual-
ity, mass ratio of oil to alcohol, operating temperature and time in addition to type of the catalyst.
28
Solid acid catalysed mechanism of esterification and transesterification of FFA with MeOH is represented
by two models, a single site Eley-Rideal (ER) and by dual-site mechanisms Langmuire Hinshelwood (LH)
[67, 92].
LH model for heterogeneous catalyst is shown in Fig.11 for the transesterification of ethyl acetate with
methanol using magnesium oxide catalyst [38]. The adsorption step (1a) and (1b) for the two reactants,
methanol and ethyl acetate, takes place on the active sites of the catalyst surface. In step 2 a surface tetra-
hedral intermediate (unstable complex) is formed from protonized carbonyl group and alkoxid group. A
fatty acid alkyl ester and diglyceride are produced in step 3 and 4 respectively [33, 38-41].
This model (dual-site) is acceptable from chemical point of view. Two reactants (Triglyceride and alco-
hol) are absorbed on the catalyst active site and the reaction takes places with the adsorbed species.
LH model is preferred when transesterification reaction takes place in present of higher carbon alcohol
while when low carbon alcohols such as methanol is used, the single site mechanisms, ER, is preferred.
As it shown in Fig.12, the alcohol is adsorbed on the catalyst site in ER mechanism. Alkoxides ion on the
surface attacks the positively polarized carbon of triglyceride which present in liquid phase,
It is shown in Fig 12 (a) ER mechanism base on Brønsted acid site type. The (ER) mechanism by solid
Lewis acid is shown in Fig 12 (b). The mechanism includes three main steps:
Physic sorption and chemisorption of triglyceride (TG) in to the catalyst site
A intermediate tetrahedral is formed when the alcohol attacks the electrophilic carbon
The final step include the cleavage of the fatty acid ester and dig glyceride from the catalyst and the
desorption from the site.
29
Figure 11: LH Mechanism for transesterification of triglycerides with Alcohol [33]
30
Figure 12: Eley-Rideal (ER) mechanism of (a) Brønsted acid and (b) Lewis solid acid catalysts
31
Esterification reaction has different limitations. The heterogeneous catalyst reaction is shown in Fig. 13
[26]. External diffusion limitation are present when methanol and triglycerides moles diffuse from the
bulk mixture fluid into the catalyst via a boundary layer around the catalyst particles (external mass
transfer, step 1). The velocity of fluid is varied and the concentration changes from CA0 (bulk
concentration) to CAs (concentration on Catalyst surface). Other limitation are represented by internal
diffusion limit resistance of fluid transfer when reactants diffuse through the catalyst pores (pore
diffusion, step 2). Adsorption limitation occurs when the reactants are adsorbed on the catalyst surface
(step 3). The transesterification reaction takes place on the surface of the catalyst (step 4).
Figure 13: Steps in a Heterogeneous Catalyst Reaction
The products face the same limitations as in steps 1, 2 and 3 take place in steps 5, 6 and 7 respectively. At
first the desorption of the products takes place (step 5). Then internal diffusion in the pores occurs when
the products are diffusing through the catalyst pores (step 6). Finally external diffusion is present when
the products (biodiesel and glycerol) are been transferred into the bulk mixture [26].
32
Figure 14: Reaction rate vs. the ratio of velocity to particle size
Figure 15: Catalyst boundary layer
The esterification rate limits by these previous steps can summarize by mass transfer diffusion resistance
and concentration gradient across the boundary layer around the catalyst particle as shown in Fig13.
Figure 14 shows the variation in reaction rate with the ratio of velocity to particle size. At low velocity
the mass transfer boundary layer thickness (figure 15) is large and diffusion limits the reaction. At higher
fluid velocity, increasing the mixing rate, the mass transfer boundary layer thickness decreases and no
longer limits the reaction rate. At a given fluid velocity (mixing rate) reaction-limiting conditions can be
achieved by using very small particles.
33
4 ANALYSIS EQUIPMENTS
4.1 Gas Chromatography (GC)
Gas chromatography GC (Fig.16) is used in order to analyse the produced biodiesel. The samples of the
produced biodiesel are diluted with solvent and internal standard solution before making the analysis in the
GC. We use 0.5 ml of solvent (Heptane), 0.011ml Internal Standard (Propylene acetate) and 0.113ml of
FAME (product) in the present work. The sample of biodiesel (FAME) is taken from the middle medium
of cylindrical product container [32].
Figure 16 GC
The GC device is connected to computer program and the analysis results are obtained as graphics, GC
analysis is explained in calculation part 5.3
A stream of an inert gas which commonly helium or argon acts as carrier pass. The detector gives analysis
as graphics [32].
Instruction on How to Use GC for Analysis of Biodiesel Yield (Model – Agilent (GC) 6890)
Equipment instruction:
1. Check the carrier gas (He and H2) tanks. They must be opened before start at least for 5 minutes.
2. Start GC using on button (power button). Wait until the machine checks each process.
3. Open the online access page on the GC computer when GC is ready
3. The GC conditions must be fulfilled as in table 13 below:
34
Table 13: GC operation setup
Inlet temperature 215
Injection Volume, l 1
FID temperature 300
H2 flow, ml/min 45
Oven program , 𝐶0 70 °C initial temp. (Hold for 0.5 min) and ramps: 10 °C / min. from 70°C -
130°C. 15°C /min from 130°C -180°C, 7 °C /min from 180°C to 200°C and
30 °C min from 200°C - 235°C . The final temperature is maintained during 7
minutes.
Air flow ml/min 450
Calibration standard Propyl acetate
Spilt ratio 80
He Make up flow, ml/min 40
Column He flow , ml/min 45
4. When checking the calibration conditions, run the blank sample to clean GC column (it can take 30 Min).
5. GC become ready for sample analysis after blank run.
4.2 Brunauer, Emmett and Teller (BET)
Adsorption and desorption phenomena are the principles of BET technique Fig 17. BET is used to estimate
catalyst surface area, pores volume and pore diameter. The catalyst sample is degassed overnight at 250
°C as drying temperature and 77.4 K for N2 adsorption.
BET recorded adsorption and desorption curves are shown in Fig.18. A BET surface area report is shown
in table 14.
35
Figure 17: BET
Table 14: BET surface Area Report
BET- Surface Area
Pore volume
Pore diameter
10.7225 𝑚2/g
0.0734 𝑐𝑚3/g
254.254 𝐴0
Figure 18 a. BET surface area, b. catalyst pore volume
Li-CaO is prepared by calcination of Ca(OH)2 with LiOH.H2O at 600°C. The exposure at high
temperature during 2 hours results in expansion of the pores diameter. Calcination improves mass transfer
diffusion and reduces internal diffusion resistance. The total surface area is reduced, surface basicity is
increased and the catalyst activity is improved. CaO surface is reduced by Lithium ions particles that fill
the micro pore of CaO [40, 81- 82].
36
Some previous researches have studied the influence of increasing lithium amount in wt.% on CaO sur-
face area. Increasing the amount of Li doping on CaO decreased the surface area dramatically (Table 15)
[67]. In experiments performed by Watkins [36] 4 wt.% Li on CaO decreased the CaO surface area from
20 to 8 m2/g. Rane found out that 28.5% wt% Li on CaO decreased the CaO surface area from 6 to 0.3
m2/g.
Table 15: Influence of lithium amount on the CaO surface area
Amount Li on CaO
wt.%
Influence on surface area of CaO
(𝑚2/g )
Reference
4 Decrease from 20 to 8 (𝑚2/g ) Watkins et al [36]
28.5 Decrease from 6 to 0.2 (𝑚2/g ) Rane et al [37]
7 Decrease from 2 to 0.076 (𝑚2/g ) Rane et al [37]
4.3 Viscosity measurement
Falling sphere viscometer DIN53015 is used in order to measure the viscosity of biodiesel (fig.19).
Figure 19 Viscosimeter
It implements Stock law to measure viscosity by calculating the falling time of the ball between lines at the
two ends of the cylinder. Measuring is repeated for 9 times.
Viscometer has inclination angle of 80 degree and operates in ±1-3 % error. The viscosity limits is in range
0,0006 – 250 N.S / m2 and the time is converted into viscosity value by using equation 1 [29].
37
Table 16: Density of different glycerol mixture and temperature [27]
% Glycerol Density
15 °C 15.5 °C 20 °C 25 °C 30 °C
0.00 0.99913 0.99905 0.99823 0.99705 0.99565
1.00 1.00155 1.00145 1.00050 0.99945 0.99500
2.00 1.00395 1.00385 1.00300 1.00180 1.00035
3.00 1.00635 1.00630 1.00540 1.00415 1.00270
4.00 1.00875 1.00870 1.00780 1.00655 1.00505
5.00 1.01120 1.01110 1.01015 1.00890 1.00735
6.00 1.01360 1.01350 1.01255 1.01125 1.00970
7.00 1.01600 1.01590 1.01495 1.01360 1.01205
8.00 1.01840 1.01835 1.01730 1.01600 1.01440
9.00 1.02085 1.02075 1.01970 1.01835 1.01670
10.00 1.02325 1.02315 1.02210 1.02070 1.01905
11.00 1.02575 1.02565 1.02455 1.02315 1.02150
12.00 1.02830 1.02820 1.02705 1.02560 1.02395
13.00 1.03080 1.03070 1.02955 1.02805 1.02640
14.00 1.03330 1.03320 1.03200 1.03055 1.02885
15.00 1.03580 1.03570 1.03450 1.03300 1.03130
16.00 1.03835 1.03825 1.03695 1.03545 1.03370
17.00 1.04085 1.04075 1.03945 1.03790 1.03615
18.00 1.04335 1.04325 1.04105 1.04035 1.03860
19.00 1.04590 1.04575 1.04440 1.04280 1.04105
20.00 1.04840 1.04825 1.04690 1.04525 1.04350
At first we measure the ball density by measuring its volume and weight:
Ball density = Ball weight / Ball volume = 3.78 g. / 2 ml. = 1,89 g/ml.
The following equation is used in order to calculate the viscosity of the produced biodiesel:
Biodiesel Viscosity = K * Full Time * (Ball Density – Biodiesel Density) (eq.1)
The contact k is calculated using a liquid of known viscosity. A mixture of 20% glycerol in water is used.
The standard density for a mixture 20% glycerol in water at 25°C is 1,045 g/ml as shown in table 16.
Viscosity of a mixture 20% glycerol 80% water at 25 °C is 1.542 g/ml as it is shown in table17.
38
The constant, k, is calculated as:
K= medium viscosity / [full time*(Ball Density-Biodiesel Density)] (eq.2)
= 1.542 / [ 4 (1.89 -1.045)] = 0,4663
4 s was the time of the ball between lines at the two ends of the cylinder.
In appendix, table 23, the calculation of the viscosity of the biodiesel is shown.
Biodiesel Viscosity = K * Full Time * ( Ball Density – Biodiesel Density )
= 0.4663. t (1.89-1.045 )
Table 17 Absolut viscosity of different glycerol mixture and temperature [28]
% Glycerol by weight Absolute Viscosity in centipoises
30 °C 25 °C 20 °C
0.00 0.800 0.893 1.005
5.00 0.900 1.010 1.143
10.00 1.024 1.153 1.311
15.00 1.174 1.331 1.517
20.00 1.360 1.542 1.769
25.00 1.590 1.810 2.095
30.00 1.876 2.157 2.501
35.00 2.249 2.600 3.040
40.00 2.731 3.181 3.750
4.4 X-Ray diffraction
XRD, shown in fig.20, is used to identify crystalline phase in a material. XRD is used to estimate structure
properties e.g. deflects, grain size, epitaxy and phase composition
The analysis is obtain as typical XRD pattern with different coolers peaks as it is shown in Fig.21 [42, 69].
39
Figure 20: XRD
Three catalyst samples A, B, and C have been prepared and analysed (table 18).
Table 18: Samples tested in XRD analysis:
Sample of
catalyst
Reflection angle Li-CaO
amount
Condition of preparing
A 37.5 1110 Ca(OH) 2 calcinated with LiOH.H2O for 2h. at 600°C.
B 37.5
820
Ca(OH)2 calcinated for 2h at 600°C. Then mixed with
half amount of LiOH.H2O and then calcinated the
mixture for 2h at 600°C. Finally mixed with the rest of
LiOH.H2O
C 37.5
720
Ca(OH) 2 calcinated for 2h at 600°C then mixed it with
total amount of LiOH2O .
Analysis start:20.000 degree and ended at 90.000 degree with step time 0.5 s and temperature 25 °C.
40
Figure 21: sample A. Li-CaO Catalyst XRD Analysis
The calcination conditions for catalyst A give higher maximum intensity of Li-CaO with angle 37 degree.
Catalyst A is selected for use in the experiments presented in this work.
41
SEMENS d 5000 OPERATING INSTRUCTION. [Ref: XRD instructions]
Switch on the x-ray diffractometer
1) Put on the cooling water (as much as possible, but do not over tighten )
2) Press the switch NETZ MAINS.
3) Check current and voltage. They should be in left bottom position (5 mA,20KV )
4) Press the YELLOW SWITCH.
5) Press shift x ray 1 enter
6) Press the GREEN SWITCH. (x-ray tube is now in function )
7) Turn the voltage to 40 KV stepwise according to schedule
Table 19: XDR setting
Retention time (min)
Stop (days) 20 kv 25 kv 30 kv 35 kv 40 kv
0,5 to 3 0.5 0.5 0.5 0.5 0.5
3 to 30 0.5 0.5 2 2 2
>30
or new tube
0.5 0.5 2 2 2
8) Turn the current from 5 to 30 mA
Shut off the XRD
1) Turn down the current to 5 mA.
2) Turn down the voltage to 20kv.
3) Press the RED SWITCH.
4) Press the NETZ MAINS.
5) Turn off the cooling water.
42
5 - EXPERIMENTAL SETUP CONDITIONS
5.1 Catalyst preparing:
CaO is widely used as a heterogeneous catalyst in biodiesel synthesis. The condition for catalyst production
such as temperature, pressure and time of sintering influence the catalyst activity and then the yield of
produced biodiesel
Lithium doped Calcium Oxide (Li- CaO) is prepared in order to be used as catalyst. In 6 experiments the
amount of catalyst is 2.5 wt % in relation to oil, while in the other 6 experiments the amount of catalyst is
increased to 5 wt % [75-81].
The catalyst consists of 99% CaO and 1% Li.
For 45 grams CaO, 0.45 g Li are it are required:
At 600 °C (calcination) the reactions takes place:
Ca(OH)2 → CaO + H2O
2 LiOH.H2O → Li2O +3 H2O
Table 20: Molecular weights for catalyst feedstock
Specie CaO Ca(OH) 2 Li2O LiOH.H2O
Mol.wt. (g/mol.) 56.08 74.1 29.9 41.96
In order to produce 45g of CaO and 0.54g of Li2O, it is required 60g of Ca(OH)2 and 1.26g of LiOH.H2O.
Ca(OH)2= CaO weight
CaO Mwt * Ca(OH)2 M.wt. =
45 g
56,08 (g
mol).
* 74.1 (g
mol) = 60 g.
LiOH.H2O= CaO weight
LiO M.wt. *( LiOH.H2O) M.wt. =
45 g
29.9 (g
mol).
* 41.96 (g
mol) = 1,26 g.
60g Ca(OH)2 and 1.26g. LiOH.H2O are crushed. The powder mixture is calcinated at 600 °C during two
hours.
43
The prepared catalyst is kept in dry and isolated place from air contact.
Li-CaO catalyst has been prepared in different conditions as it is shown in table 21.
Table 21: Biodiesel yield by using Li/CaO with different feedstock [90, 91]
Feedstock
Cat. weight %
Cat. Preparation
Operation conditions
yield
Karana oil
3.4 wt.% FFA
Impregnated with 1.75
wt.% of lithium and
heated at 120 °C for 24 h
T=65 °C, t=60 min,
alcohol/oil=12:1,catalyst
content=5%
>99%
Jatropha oil
8.3 wt.% FFA
Impregnated with 1.75
wt.% of lithium and
heated at 120 °C for 24 h
T=65 °C, t=120 min,
alcohol/oil=12:1,catalyst
content=5%
>99%
Used
cottonseed oil
15 wt.%
moisture
Impregnated with 1.5 wt.%
of lithium and
heated at 120 °C for 24 h
T=65 °C, t=150 min,
alcohol/oil=12:1,catalyst
content=5%
>99%
Rapeseed oil
5%
Calcination 575 °C for 4 h
alcohol /oil=12:1,catalyst
content=5%
>93%
5.2 Reaction and Retention time
The operation system consists of a small glass batch reactor with three necked. It is immersed in a hot
bath water controlled by electrical heater and thermometer as it is shown in Fig.22.
The catalyst activity is studied changing operation conditions. The influence of the ratio alcohol to Oil,
operating temperature, time of reaction, agitation rate and amount used catalyst on the yield and quality of
the produced biodiesel is studied.
Final sample product is kept in graduated glass cylinder as it is shown in Fig.23. After 24 h, different layers
of products are formed due to the difference in density.
The layers from the top cylinder to the bottom are: unreacted methanol, FAME, glycerol and catalyst.
In order to analysis the biodiesel, the sample is taken from the graduate cylinders from middle.
44
Figure 22: Experimental operation system
Figure 23: graduated cylinder
Each biodiesel sample introduced to the GC consist of heptane (0.5 ml), the produced biodiesel (0.113 ml)
and internal standard (IS) (0.011ml). The sample is placed in the GC injector to start the analysis.
It is very important to keep the samples in an isolate place away from the sunlight to avoid decomposition.
It is difficult to take the catalyst from graduated cylinder in order to reuse it. The catalyst sticks with glycerol
as one phase material. It can be separated by using thermal and physical methods which increase the running
cost in generally [89].
45
5.3 Calculations
Transesterification reaction is a reversible reaction:
3 alcohol (MeOH ) + 1 Oil (Triglyceride) = 3 biodiesel (FAME) + Glycerol
The theoretical amount of biodiesel which can be obtained assuming 100% conversion, is calculated.
Amount of oil volume = 60 mL in each experiment
Oil weight = Oil Volume x Oil density = 60 mL x 0.915 g / mL = 54.9 g
Oil molecular weight = 880 g / mol.
Oil mole = Oil weight / Oil molecular weight
= 54.9 g / 880 g / mol. = 0.0623 mol.
According to stoichiometry of the reaction, one mole of oil produces three mole of FAME.
Theoretical yield of FAME = 3 x 0.0623 mol. = 0.187 mol of biodiesel.
The real yield of FAME for each experimental is calculated using the results from GC analysis which appear
as different peaks at different retention time depends on FAME composition. The total area of those peaks
is divided by internal standard peak area, and then multiplied by the concentration of internal standard and
by the inverse of response factor in order to calculate the concentration of FAME in each sample.
Concentration of FAME = Area of FAME
A rea of IS * Concentration of IS. *
1
Response Factor
In order to calculate the response factor, two ratios (relations) are calculated:
Ratio 1 = Concentration of standard FAME
Concentration of IS = = 10 (relation between concentrations)
Ratio 2 = total FAME peak area
IS peak area =
40864,4
1773,9 = 23.036 (relation between areas)
Response factor = Ratio 2
Ratio 1 =
23,036
10 = 2.3
46
In the sample introduced to the GC the biodiesel is diluted with heptane and internal standard.
Real Concentration of FAME = Volume of sample ∗ Concentration of FAME
Volume of FAME
6 - RESULTS and DISCUSION
6.1 Temperature Influence
The boiling point of methanol is 64.7 °C and in order to avoid alcohol evaporation, reaction temperature
has to be less than 64.7 °C. The optimal temperature runs between 50 and 60 °C. Increasing the temperature
will reduce the viscosity of the oil which leads to a sufficient contact at the active site of catalyst surface
between the oil and the methanol. As a result, a higher yield of biodiesel is obtained [7, 23, and 24].
The reaction temperature has a positive influence on FAME yield as it is shown in fig.24. The temperature
range of 60–63 °C for 6:1 methanol to rapeseed oil mole ratio at atmospheric pressure is studied. The yield
of produced biodiesel increases when both the temperature and agitation rate are increased from 60 to 63
°C and from 160 to 320 rpm respectively at constant time (1h) (figure 24).
Figure 24: Effect of temperature on FAME yield.
Figure 24 shows the influence of the temperature and the ratio alcohol to oil on the yield of produced
biodiesel.
77,8
80,6
77,8
84
59 60 61 62 63 64
77
78
79
80
81
82
83
84
85
Temp, °C
Yiel
d %
6:1 Mole R., 2,5% Cat., I hr. , 60-63 C,160 rpm.
6:1 Mole R., 2,5% Cat , I hr, 60 -63 C ,160-330 rpm.
47
At 60°C the yield of produced biodiesel is increased from 77.8% to 95% when the ratio alcohol: oil is
increased from 6 to 9, and the amount of catalyst is increased from 2.5 wt% to 5wt%. At higher temperature,
at 63 °C, an increase of the alcohol: oil ratio and of the amount of catalyst does not influence the yield of
produced biodiesel in a positive way (figure 25).
An increase of temperature from 60 to 63 °C, using an alcohol: oil ratio of 9 and 5 wt% amount catalyst,
does not increase the amount of produced biodiesel. Using an alcohol: oil ratio = 6 and 2.5 wt% catalyst,
an increase of temperature only produces a slight increase of the amount produced biodiesel (figure 25).
At 63°C, close to methanol boiling point, the evaporation of methanol possible increases.
Figure 25: Effect of temperature on FAME yield.
6.2 Amount catalyst
An insufficient amount of catalysts results in an incomplete conversion of the triglycerides into the fatty
acid esters [23, 25]. During experiment, the catalyst loading is varied in the range of 2.5 to 5 wt. % rapeseed
oil weight as it is shown in figure 26 for three different methanol – oil mole ratios 6:1, 9:1 and 12:1 respec-
tively.
Figure 26 shows the influence of the amount of catalyst and the alcohol to oil ratio on the yield of produced
biodiesel. An increase of the amount of catalyst from 2.5 wt% to 5 wt% does not increase the amount
produced biodiesel. An amount of 2.5 wt% catalyst is enough catalyst in order to achieve high yield of
biodiesel [34].
An increase of the alcohol ti oil ratio from 6 to 12 increases the yield of produced biodiesel, at the studied
conditions (160 rpm agitation rate and 2 h reaction time).
77,8 80,6
95
72
59 60 61 62 63 64
0
20
40
60
80
100
Temp.C
Yiel
d %
6:1 Mole Ratio, 2,5% Cat. , I hr. ,160 rpm , 60-63 C
9:1 Mole Ratio, 5% Cat. , I hr ,160 rpm , 60-63 C.
48
Figure 26: Effect of Catalyst % on FAME yield.
6.3 Mixing rate
Agitation rate influences on biodiesel yield at constant methanol-oil mole ratio (6:1), 2,5% catalyst loading
and different reaction temperatures 60 and 63°C (figure 27).
Increasing mixing intensity (at constant catalyst loading) from 160 to 320 rpm has affected the FAME yield.
At 60 °C the yield of produced biodiesel has increased with mixing rate. At 63 °C the yield of biodiesel
has decreased when mixing rate is increased from 160 to 320 rpm.
Figure 27: Effect of mixing intensity on FAME yield.
Increasing agitation rate improves mass transfer of reactants on active sites of catalyst surface due to
decreasing the boundary layer between the catalyst surface and the fluid bulk as it shown in Fig.28. This
leads to reduce the external diffusion resistance of reactants and products around the catalyst surface.
Increasing the temperature together with agitation speed leads to increase the reaction rate due to decreasing
the activation energy of the reaction [26].
77,8 73,8
95
78,85
97 96
0 1 2 3 4 5 6
0
20
40
60
80
100
120
Catalyst , wt.%
Yie
ld %
2.5-5 % Cat., 6:1 mole ratio, 1 h. ,60 °C ,160 rpm.
2.5-5 % Cat., 9:1 mole ratio, 1 h. ,60 °C ,160 rpm.
2.5-5 % Cat., 12:1 mole ratio, 1 h. ,60 °C ,160 rpm.
77,8
84
80,6
76
0 100 200 300 400
74
76
78
80
82
84
86
mixing intensity , RPM
Yiel
d %
6:1 mole ratio, 60 C, 1 hr.2,5% Cat., 160-320 rpm
6:1 mole ratio, 63 C, 1 hr.2,5% Cat., 160-320 rpm
49
At 63 °C, a decrease of the yield occurs when the mixing rate is increased due the increase of the evaporation
of the methanol at temperatures close to the boiling point.
Figure 28: External resistance to mass transfer [26]
6.4 Alcohol to oil ratio
Effect of methanol - oil molar ratio is investigated as it is shown in Fig.29 with three different molar
ratios 6, 9 and 12 respectively during one hour operation time at constant temperature 60 °C and constant
rate of mixing, 160 rpm, while the catalyst amount has been changed from 2,5 % to 5% based on the
weight of oil.
Increasing of molar ratio achieves a proportional increasing of biodiesel yield % from 77.8 to 97 % for
the first used amount of catalyst (2.5% of oil weight) and from 73.8 to 96 % for the second test with
catalyst weight 5 wt% (oil weight).
An excess of methanol shifts the reaction to the right and higher amount biodiesel is produced [19].
Figure 29: Effect of methanol-oil mole ratio on FAME yield
77,8
95 97
73,8 78,85
96
0 5 10 15
0
20
40
60
80
100
120
Mole Ratio
Yiel
d % 2,5% Cat.,1hr,160 rpm, 60
C, (6-9-12)/1 mole ratio.
5% Cat.,1hr,160 rpm, 60 C, (6-9-12)/1 mole ratio
50
Figure 30 shows the influence of the alcohol to oil ration on the yield of obtained biodiesel for 2h reaction
time, catalyst amount 2,5 wt% to 5 wt% at constant temperature 60 °C and constant rate of mixing 160 rpm.
The yield of produced biodiesel increases with the alcohol to oil ratio. Using lower amount of catalyst (2.5
wt%) a high yield of biodiesel is obtained using an alcohol to oil ratio of 9. A further increase of alcohol to
an alcohol to oil ratio of 12, increases slight the yield of biodiesel.
Figure 30: Effect of methanol-oil mole ration on FAME yield
6.5 Reaction time
The effect of the reaction time on biodiesel yield in a batch reactor through is studied changing the reaction
period. Generally the effect of reaction time inside a reactor can be calculated by using the residence time
distribution method (RTD) to compute the expected conversion with time. There will be different reaction
times due to different RTD [24-26].
In our system (batch), effect of reaction time obviously increases biodiesel yield from 77,8 to 83% at
alcohol to oil ratio 6:1 when the reaction time increases from 1 to 2 h at constant temperature 60 °C, at
fixed agitation rate 160 rpm and 2,5% catalyst load (base of oil weight) as it is shown in Fig.31..
At higher alcohol to ratio (9:1 and 12:1), an increase of reaction time from 1 to 2 hours does not increase
the yield of produced biodiesel.
At higher amount of catalyst (5 wt%) an increase of the reaction time from 1 hour to 2 hour does not increase
the yield of produced biodiesel at the studied conditions.
8394 99,7
63
81,791,8
0 5 10 15
0
20
40
60
80
100
120
Mole Ratio
Yiel
d % 2,5% Cat.,2hr,160 rpm, 60 C,
(6-9-12)/1 mole ratio
5% Cat.,2 hr,160 rpm, 60 C, (6-9-12)/1 mole ratio
51
Figure 31: Effect of Reaction time on FAME yield
Figure 32: Effect of Reaction time on FAME yield
6.6 Waste cooking oil
Some experiments have been performed with waste cooking oil. Figure 33 shows that the yield of produced
biodiesel increases from 62.7 to 70.4 % when the temperature is increased from 55 °C to 60 °C and the
mixing rate is increased from 160 to 320 rpm.
An increase of the amount of catalyst (from 2.5 wt% to 5 wt%) does not increase the amount of produced
biodiesel at 320 rpm mixing rate, 60 °C, and alcohol to oil ratio of 6:1.
77,8 8395 9497 99,7
0 0,5 1 1,5 2 2,5
0
20
40
60
80
100
120
Time , h.
Yiel
d %
1-2 hr, 2.5% Cat.,6:1 mole ratio , 160 rpm 60C
1-2 hr, 2.5% Cat.,9:1 mole ratio , 160 rpm 60C
1-2 hr, 2.5% Cat.,12:1 mole ratio , 160 rpm 60C
73,863
78,85 81,7
96 91,8
0 0,5 1 1,5 2 2,5
0
20
40
60
80
100
120
Time , h.
Yiel
d %
1-2 hr,5% Cat., 6:1 mole ratio , 160 rpm 60C
1-2 hr, 5% Cat.,9 :1 mole ratio , 160 rpm 60C
1-2 hr, 5% Cat.,12 :1 mole ratio , 160 rpm 60C
52
Figure 33: Yield of produced biodiesel vs temperature. Waste cooking oil.
Waste cooking oils have contain high amounts of free fatty acids.
The alkaline catalysts react with FFAs to form soap that prevents the separation of the glycerol and ester.
Biodiesel production from feed stocks with high FFA (free fatty acids) is extremely difficult using alkaline
homogeneous catalyzed transesterification. Also heterogeneous catalyzed transterification is affected by
the high amount of free fatty acids
Sulphuric acid and hydrochloric acid are normally used as acid catalysts especially when the oil contains
high amount of free fatty acids and water. In the two-step method a pre-esterification operation is applied
to eliminate free fatty acids (FFAs) by reacting the oil with alcohol in the presence of an acid catalyst.
The purified oil was further reacted with alcohol in the presence of an alkali catalyst.
The purification of the oil, removing the impurities such as suspension catalyst solid particles, drops water,
soap, unreacted alcohol and unfiltered catalysed is very important. Unwashed biodiesel leads to fuel
degrades, reduce fuel lubricity, explosion and can corrode engine components.
6.7 Conversion vs. reaction time
Experiments are carried out with 6:1 methanol-oil mole ratio, 60 °C, 2.5% catalyst loading, 160 rpm
agitation speed and for 65 minutes reaction time.
Seven samples of 10 ml are taken every 10 min. from the reactor as shown in table 22.
In figure 34 it is observed that the yield for the first four samples, taken between 10 and 40 min, increases
slowly. The amount of biodiesel contained in samples 5 and 6, taken between 50 and 60 min, increased
markedly. In the sample 7 taken at 65 min a yield of biodiesel of 92% is obtained.
62,770,4
55,6
54 56 58 60 62
0
10
20
30
40
50
60
70
80
160-320 rpm,55-60 C ,6:1 Mole Ratio, 1 h.,2,5% Cat.
320 rpm,60 C ,6:1 Mole Ratio, 1 h., 2,5-5% Cat.
53
Table 22: Triglycerides conversion vs. FAME yield%
Sample 1 2 3 4 5 6 7
Time (min) 10 20 30 40 50 60 65
Yield % 11.1 12 16.27 23 32.7 55.8 91.7
Figure 34: Triglycerides conversion vs. FAME yield%
6.8 Accuracy and Error of results
Any experimental work has some expectations errors occur and limit the study results due to inaccuracy
readings of final results since it depends on visual reading for the intervals between the product layers in
graduate cylinders e.g. the volume of the glycerol sometime can be difficult to read samples FFA volume
which effect extremely on the study calculation .
Catalytic activity is influenced significantly by calcination temperature where the catalyst preparation de-
pends only on one temperature (600 C) of calcination. [87-88].
Many errors can happen in viscosity measuring. Falling time is used here. It can be errors in measuring the
time of ball falling. Counting the falling time of the ball is based on the average of ten readings in order to
avoid error of falling time.
The most effected error comes when catalyst contacts with atmosphere air. This leads to absorb carbon
dioxide by the catalyst and influence catalyst activity. This phenomena can be avoided by using a vacuum
place to keep the catalyst fresh along the experiment time.
11,1 12 16,323
32,7
55,85
91,73
0 10 20 30 40 50 60 70
0
10
20
30
40
50
60
70
80
90
100
time , min.
Yie
ld %
Yield vs. time
54
GC samples are prepared after some days of experiment date. This can involve some errors in measuring
the yield of biodiesel through GC analysis.
7- CONCLUSION
The study aims to optimize operation conditions parameters for esterification of triglycerides for produc-
ing biodiesel catalysed by Li-CaO heterogeneous catalyst. Calcium oxide impregnated with Li was shown
to be effective for the complete transesterification of rapeseed oil at 60°C with an oil/methanol molar ra-
tio of 1:12, 160 rpm agitation speed and with 2.5 wt % catalyst (based on the weight of rapeseed oil) in
one hour.
It demonstrates that Li-CAO catalyst particle exhibits high catalytic activity in the transesterification reac-
tion for biodiesel production by using rapeseed oil an edible vegetable oil in reliable easy and safety way.
Esterification reaction of TG with a 12:1 methanol - oil mole ratio has the highest yield (97% to 99.7 %
yield of the FAME).
Raising operation temperature under a temperature range lower than methanol boiling point will increase
the yield. An efficient process require a good agitation rate. At 63 °C, close to the methanol boiling point,
the yield of obtained biodiesel can decrease under certain conditions (high mixing velocity) because the
evaporation of the methanol.
An increase of the amount of catalyst from 2.5 wt% to 5 wt% does not increase the amount produced
biodiesel. An amount of 2.5 wt% catalyst is enough catalyst in order to achieve high yield of biodiesel
At 60 °C, the yield of obtained biodiesel increase when the mixing rate increases from 160 to 320 rpm.
The yield of produced biodiesel increases with the alcohol to oil ratio.
At alcohol to oil ratio 6:1 the yield of produced biodiesel increases when the reaction time increases from
1 to 2 hours. At higher alcohol to ratio (9:1 and 12:1), an increase of reaction time from 1 to 2 hours does
not increase the yield of produced biodiesel.
The development of the reaction has been studied showing the relation conversion vs reaction time. At 65
min a yield of 92% has been obtained with a 6:1 methanol-oil mole ratio, 60 °C, 2.5% catalyst loading, 160
rpm agitation speed.
Experiments using waste cooking oil has been performed showing a lower conversion the high amount of
free fatty acids in the waste cooking oil, forming soaps that prevents the separation of the glycerol and ester.
It is recommended to perform further kinetic studies at long time operation condition. The reusability of
catalyst as well as the use of waste cooking oil should be further studied.
55
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61
9. ANNEXES
Table 23 samples viscosities
Sample VT(ml) V Bio V Cat. V Gly. V MeOH Fall.tim.(s) Viscos. Cp
0 118 107 7 4 0 5 1.9
1 66 51 10 5 0 6.5 2.47
2 74 60 9 5 0 5.5 2.09
3 74 60 6 8 0 4.5 1.71
4 68 49.5 13 5 0.5 7.5 2.85
5 76 52 13.5 10 0.5 4 1.52
6 83 62.5 19 1 0.5 4.5 1.71
7 67.5 46.5 16 4 1 5.5 2.09
8 78.5 46 17.5 4.5 0.5 7.5 2.85
9 86 63 12 1 10 4 1.52
10 66 42.5 20 3 0.5 6.5 2.47
11 71 51 15 5 0 4.5 1.71
12 77 58 13 5 1 4.5 1.71
13 66 48 12 5 1 4.5 1.71
14 64 51 10 2 1 6.5 2.47
15 66 57 5 4 0 5 1.9
16 75 57 15 3 1 4.5 1.71
17 71 61 6 4 0 4.8 1.82
18 77 67 8 2 0 4.89 1.86
19 67 62 3 2 0 5.1 1.94
20 66 50 15 1 0 5 1.9
21 67 54 11 2 0 5 1.9
22 66 48 16 2 0 5 1.9
62
Table 24: Experimental Result
63
Table 25 Experimental Result
