THESIS TK142541 KINETIC STUDY OF CARBON DIOXIDE …
68
THESIS TK142541 KINETIC STUDY OF CARBON DIOXIDE ABSORPTION INTO GLYCINE PROMOTED METHYLDIETHANOLAMINE (MDEA) Presented By : YOSRY ELHOSANE AHMED ELHOSANE 2314201 701 Supervisors : Prof. Dr. Ir. ALI ALTWAY, M.Sc NIP. 1951 08 04 1974 12 1001 Dr. Ir. SUSIANTO, DEA NIP.1962 08 20 1989 03 1004 MASTER PROGRAM CHEMICAL ENGINEERING DEPARTMENT FACULTY OF INDUSTRIAL TECHNOLOGY INSTITUT TEKNOLOGI SEPULUH NOPEMBER SURABAYA 2016
Transcript of THESIS TK142541 KINETIC STUDY OF CARBON DIOXIDE …
THESIS TK142541
KINETIC STUDY OF CARBON DIOXIDE ABSORPTION INTO
GLYCINE PROMOTED METHYLDIETHANOLAMINE
(MDEA)
Presented By : YOSRY ELHOSANE AHMED ELHOSANE
2314201 701
Supervisors :
Prof. Dr. Ir. ALI ALTWAY, M.Sc
NIP. 1951 08 04 1974 12 1001
Dr. Ir. SUSIANTO, DEA
NIP.1962 08 20 1989 03 1004
MASTER PROGRAM
CHEMICAL ENGINEERING DEPARTMENT
FACULTY OF INDUSTRIAL TECHNOLOGY
INSTITUT TEKNOLOGI SEPULUH NOPEMBER
SURABAYA 2016
KINETIC STUDY OF CARBON DIOXIDEABSORPTION INTO GLYCINE
PROMOTED METHYLEDIETHANOLAMINE
(MDEA)
Student Name : Yosry Elhosane Ahmed Elhosane
Advisors : 1. Prof. Dr. Ir. Ali Altway, M.Sc
2. Dr. Ir. Susianto, DEA
Abstract
Carbon dioxide is commonly seen as one of the major contributors to climate
change that is why removing carbon dioxide from the chemical industry field is very
important things to mitigate the problem of global warming, so we need to reduce CO2
emissions by using the optimized method .
The chemical absorption using tertiary alkanolamines solution one of must
important method which have been proposed and studied for the removal of carbon dioxide,
because the MDEA solvent has low cost, low corrosive tendencies, high stability, low
viscosity, low tendency to foam, and low flammability, however it has low reaction rate
therefore added glycine as promoter to conventional solvents and to increase the rate of the
reaction, because glycine is a primary amine compound which is reactive, moreover, glycine
has resistance to high temperatures so it will not easy to degradable and suitable for
application in industry.
The main purpose of this study is to provide reaction kinetics data of CO2
absorption into glycine promoted methyldiethanolamine(MDEA) by using laboratory scale
wetted wall column equipment at the atmospheric pressure by varying temperature from
303,15 to 328,15 and glycine concentration from 1%to 3% and the carbon dioxide absorption
rate is measured by titration of liquid effluent
Based on the result of this study, we observed that by increasing temperature and
concentration of glycine ,the absorption rate of carbon dioxide in MDEA solution will
increase, In addition the reaction rate constant will be affected by the temperature and the
concentration of promoter. The correlation of reaction rate constant k glycine is: k glycine
=5.3409E+13exp(-3251.9/T) with activation energy for glycine promoter is 27.0363 kJ/kmol.
Key words : reaction kinetic ;carbon dioxide absorption; promoter ; wetted column.
CONTENTS
ABSTRACT.............................................................................................................i
CONTENS ............................................................................................................iii
LIST OF FIGURES...............................................................................................v
LIST OF TABLE.................................................................................................vii
NOTATION..........................................................................................................ix
CHAPTER 1 INTRODUCTION
1.1 Background...................................................................................1
1.2 Research problem…......................................................................5
1.3 Objective of the project.................................................................5
CHAPTER 2 LITERATURE REVIEW
2.1 The method of removal carbon dioxide ..........................................7
2.2 capture technology ..........................................................................7
2.2.1 Adsorption.......................................................................................8
2.2.2 Membranes ......................................................................................8
2.2.3 Membrane gas absorption ...............................................................8
2.2.4 Gas separation membranes ............................................................9
2.2.5 cryonics separation..........................................................................9
2.2.6 Physical absorption .........................................................................9
2.2.7 chemical absorption ........................................................................9
2.3 Absorption process............................................................................10
2.4 Absorption with chemical reaction ................................................10
2.5 Procedures with alkanoamines .........................................................12
2.5.1 Reaction mechanism of alkanoamines ........................................13
2.5.2 Reaction kinetics of carbon dioxide ............................................13
2.6 Gas-liquid contactors ........................................................................15
2.7 Carbon dioxide in wetted wall column ...........................................15
2.8 Reaction regimes .............................................................................17
2.9 The previous works .........................................................................18
CHAPTER 3 RECEARCH METHODOLOGY
3.1 Description of research ...................................................................21
3.2 Materials and equipment ................................................................21
3.2.1 Materials ....................................................................................21
3.2.2 Research Equipment ..................................................................21
3.3 Operating conditions and variables research ..................................24
3.4 Research procedure .........................................................................25
3.5 Data evaluation ...............................................................................26
CHAPTER 4 RESULTS AND DISCUTIONS
4.1 The effect of temperature and concentration of promoter on carbon
dioxide absorption rate ....................................................................29
4.2 The effect of temperature and promoter concentration
on outlet concentration of carbonate ............................................... 30
4.3 Carbon dioxide recovery ................................................................31
4.4 Reaction rate constant ....................................................................32
4.4.1 Glycine promoter reaction rate constant .........................................32
4.4.2 Apparent reaction rate constant (kapp) ...........................................33
4.5 Compression between k glycine and another rate constant promoter
.........................................................................................................34
4.6 Comparison between glycine promoted MDEA and DEA promoted
MDEA .............................................................................................36
4.6.1 The rate of carbon dioxide absorption .............................................36
4.6.2 The reaction rate constant .................................................................36
4.6.3 DEA constant rate for this study and previous study .......................37
CHAPTER 5 CONCOLUSION
5.1 Conclusion .....................................................................................39
References ......................................................................................41
LIST OF FIGURES
Figure 2.1 Mass Transfer of Gas into Liquid with Chemical Reaction….......11
Figure 2.2 Structure of alkanoamine ………………………………………....12
Figure 2.3 Structure of glycine ........................................................................ 12
Figure 2.4 Velocity discretion in a wetted wall column .................................. 16
Figure 3.1 Wetted wall column type ............................................................... 23
Figure 3.2 Eexperimental set up ..................................................................... 23
Figure 4.1-a The effect of temperature and promoter concentration on carbon dioxide
absorption rate .................................................................................................. 29
Figure 4.1-b The effect of temperature and concentration promoter on carbon dioxide
absorption rate .................................................................................................. 30
Figure 4.2 The effect of temperature and concentration of promoter on carbonate final
concentration .................................................................................................... 31
Figure 4.3 The effect of temperature and concentration promoter on overall constant rate
reaction ............................................................................................................. 32
Figure 4.4 The effect of temperature and concentration of promoter on promoter reaction rate
constant ............................................................................................................ 33
Figure 4.5 The effect of temperature inverse and concentration of promoter on apparent
reaction rate constant (kapp) ............................................................................ 34
Figure 4.6 Comparison of k glycine with another rate constant promoter
.......................................................................................................................... 36
Figure(4.7) Comparison of the effect of temperature on carbon dioxide absorption rate for
glycine and DEA .............................................................................................. 36
Figure(4.8) Comparison of glycine and DEA constant rate using MDEA ...... 37
Figure (4.9) :Comparison of DEA constant rate for this study and previous study 38
Figure 4.10 :Comparison of kov constant rate for this study and previous using MDEA
solvent…………………………………………………………………38
LIST OF TABLE
Table 4.1 carbon dioxide recovery…………………………………………………………...31
Table 4.1 comparison of reaction rate constant of carbon Dioxide for several solvent
………………………………………………………………………………………………..35
NOTATION
A Pre-exponensial factor
BF film wide(m)
CB0 concentration of reactant (kmol m-3
)
CA Concentration of CO2 in the liquid (kmol m-3
)
CAi Concentration of CO2 at the interface (kmol m-3
)
CAe Equilibrium concentration of CO2with liquid (kmol m-3
)
Ci Ion concentration of the valence Zi (kmol m-3
)
d pipediameter of liquid (m)
DAG diffusion coefficient of gas CO2 (m2s
-1)
DAL Diffusivityof CO2 into H2O, (m2/s
-1)
DBL Diffusivity of CO32-
into H2O, (m2
s-1
)
E Activation energy (kg m-2
s2)
Ei Enhancement factor
g Gravity (m s-2
)
h High of column (m)
Ha Hatta number
He Henry constant (Pa m3 kmol
-1)
He0 Henry constant for gas-liquid system (Pa m
3 kmol
-1)
kapp kov - kOH- [OH-] - kDEA[DEA] (s
-1)
kov Reaction constant overall pseudo first order (s-1
)
kOH- Reaction rate constant from reaction (2.11) (s-1
)
kH2O Reaction rate constant from reaction(2.10) (s-1
)
kglycine Reaction constantof glycine (m3/kmol.s)
kappglycine kglycine[glycine] (s-1
)
kg Mass transfer coefficient of gas (kmol m-2
s-1
)
kL Mass transfer coefficient of liquid, (kmol m-2
s-1
)
KMDEA Reaction constant of Methyldiehanolamine (MDEA)
K1 Equilibrium constant for The first ionization of carbonic acid (kmol/m3)
K2 Equilibrium constant The second ionization of carbonic acid (kmol m-3
)
Kw Ionization of water (kmo2.
m-6
)
MB Molecular Wight of solvent (kg.kmol-1
)
MW Molecular Wight of water (kg.kmol-1
)
PA Partial pressure of CO2 (Pa)
PAi Partial pressure ofCO2 atinterface (Pa)
q Total absorption rate (kmol s-1
)
Q The amount of gas which absorbed (kmol m-2
)
rov Overall reaction rate (kmol/ m3 s)
R Gas constant (m3 Pa kmol
-1 K
-1)
Absorption rate per area after contact time t (kmol m-2
s-1
)
Re Reynold number
Sc Schmidt number
Sh Sherwood number
tc Contact time of gas at surface (s)
T Temperature (K)
U Velocity distribution at the liquid film (m s-1
)
Us Velocity at film surface (m s-1
)
VA Molar volume ( m3/kmol)
V Liquid flow rate (m3s
-1)
x Distance from the liquid film (m)
Zi valence ion
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Chapter 1
Introduction
1.1-Background
It is widely accepted that increasing carbon dioxide ( ) emissions to
our atmosphere is the major contributor to global climate change , which pollutes
environment.
Global warming and climate change refer to an increase in average global
temperatures. Natural events and human activities are believed to be contributing
to an increase in average global temperatures. This is caused primarily by
increases in ―greenhouse‖ gases such as Carbon Dioxide and trace gases .
The term greenhouse is used in conjunction with the phenomenon known
as the greenhouse effect. Described as follows: Energy from the sun drives the
earth’s weather and climate and heats the earth’s surface. In turn, the earth
radiates energy back into space. Some atmospheric gases (water vapour, carbon
dioxide, and other gases) trap some of the outgoing energy, retaining heat
somewhat like the glass panels of a greenhouse. These gases are therefore known
as greenhouse gases. The greenhouse effect is the rise in temperature on Earth as
certain gases in the atmosphere trap energy. A warming planet thus leads to a
change in climate which can affect weather in various ways.
Carbon dioxide ( ) is the primary greenhouse gas emitted through
human activities. In 2013, CO2 accounted for about 82% of all U.S. greenhouse
gas emissions from human activities. Carbon dioxide is naturally present in the
atmosphere as part of the Earth's carbon cycle (the natural circulation of carbon
among the atmosphere, oceans, soil, plants, and animals). Human activities are
altering the carbon cycle—both by adding more CO2 to the atmosphere and by
influencing the ability of natural sinks, like forests, to remove CO2 from the
atmosphere. While CO2 emissions come from a variety of natural sources, human-
related emissions are responsible for the increase that has occurred in the
atmosphere since the industrial revolution, the main human activity that emits
2
CO2 is the combustion of fossil fuels (coal, natural gas, and oil) for energy and
transportation, although certain industrial processes and land-use changes also
emit CO2. The main sources are described below.
Electricity is a significant source of energy in the United States and is
used to power homes, business, and industry. The combustion of fossil
fuels to generate electricity is the largest single source of CO2 emissions in
the nation, accounting for about 37% of total U.S. CO2 emissions and 31%
of total U.S. greenhouse gas emissions in 2013. The type of fossil fuel
used to generate electricity will emit different amounts of CO2. To produce
a given amount of electricity, burning coal will produce more CO2 than oil
or natural gas.
Transportation. The combustion of fossil fuels such as gasoline and
diesel to transport people and goods is the second largest source of CO2
emissions, accounting for about 31% of total U.S. CO2 emissions and 26%
of total U.S. greenhouse gas emissions in 2013. This category includes
transportation sources such as highway vehicles, air travel, marine
transportation, and rail.
Industry. Many industrial processes emit CO2 through fossil fuel
combustion. Several processes also produce CO2 emissions through
chemical reactions that do not involve combustion, for example, the
production and consumption of mineral products such as cement, the
production of metals such as iron and steel, and the production of
chemicals. Fossil fuel combustion from various industrial processes
accounted for about 15% of total U.S. CO2 emissions and 12% of total
U.S. greenhouse gas emissions in 2013. Note that many industrial
processes also use electricity and therefore indirectly cause the emissions
from the electricity production.
Carbon dioxide is constantly being exchanged among the atmosphere,
ocean, and land surface as it is both produced and absorbed by many
microorganisms, plants, and animals. However, emissions and removal of CO2 by
3
these natural processes tend to balance.In the United States, since 1990, the
management of forests and non-agricultural land has acted as a net sink of CO2,
which means that more CO2 is removed from the atmosphere, andstored in plants
and trees, than is emitted. This sink offset about 13% of total emissions in 2013 .
Environmental solutions are necessary to reduce the emissions
mainly responsible of anthropogenic greenhouse effect. This study focused on one
of the solutions using reactive absorption technology to remove .
Absorption solvents:
Since absorption has such advantages as large capacity, high efficiency
and good industrial performance, it always has been favored by researchers. The
selective chemical absorption of by a solvent is the most well-established
method of capture in power plants and from the gas sources. High product
yields and purities can be obtained with this method.
When a choice is possible, preference is given to solvents with high
solubility's for the target solute and high selectivity for the target solute over the
other species in the gas mixture. A high solubility reduces the amount of liquid to
be circulated. The solvent should have the advantages of low volatility, low cost,
low corrosive tendencies, high stability, low viscosity, low tendency to foam, and
low flammability. Since the exit gas normally leaves saturated with solvent,
solvent loss can be costly and can cause environmental problems. The choice of
the solvent is a key part of the process economic analysis and compliance with
environmental regulations.
Alkanolamines solution is one of the most effective solvents. Chemical
absorption with aqueous alkanolamine solutions like mono ethanol amine (MEA)
are commonly used absorption liquids. Alkanolamine solutions, including
monoethanolamine (MEA)-based processes, have been widely used in capturing
from natural gas sources.The removal of carbon dioxide ( ) from natural
gas and refinery gases or fossil fuel combustion is frequently accomplished by
using aqueous alkanolamine solutions. Among the alkanolamines N-
methyldiethanolamine (MDEA) is widely used as an absorption solvent for acid
4
gases. Addition of primary and secondary amine as a solution is found in
absorption to remove which will be used as the raw material of one of the
chemical industry. With the primary and secondary amine we gets a high
absorption rate and low reaction heat.
Because one of the most important information which needed to
estimate mass transfer enhancement of gas-liquid on gas absorption followed by
chemical reaction is kinetic data, many researchers have been done to learn about
kinetic data for reaction of gas-liquid. (Xu, 1995) learnt about kinetic of the
reaction of CO2 gas with 2-Amino-2-methyl-1-propanol solutions. (Davis.A.R and
Sandall.O.C, 1993 ), had learnt about kinetic of the reaction of Carbon
dioxidewith secondary Amines in Polyethylene Glycol solution. Rinker, et al.
(1994) studied about the kinetics and modelling of the absorption of CO2 in
solution of N-MDEA. Pacheco et al. (1998) explain that the absorption
ofCO2using Methyldiethanolamine (MDEA) the amount of gas that is absorbed is
controlled by fast reaction diffusion and is not affected by the detention gas-film,
Huttenhuis (2008) studied about kinetics of the reaction of pure CO2with the N-
MDEA in aqueous solution. MDEA solvent chosen as the absorbent because it
has several advantages such as : a low vapour pressure, it is not easy degradation,
low corrosive, low reaction heat, high selectivity to remove , and more
attractive. Likewise Polasek, 1994 compared MDEA compounds with other
amine compounds, the result acid gas loading, a higher concentration of MDEA
in the (strength) solution can get 50-55% higher mass with lower corrosively,
degradation resistance is higher, the reaction heat more low and low vapour
pressure.
Aqueous solutions containing salts of amino acids represent further
candidate solvents having good potential for capture. Due to their ionic
nature, these salt solutions exhibit low volatility, high surface tension, and
increased resistance to oxidative degradation. Their reactivity and CO2 absorption
capacity are comparable to those of aqueous amines of the related classes. They
are also added as promoters to conventional solvents. Some examples of
commercial interest are glycine (Giammarco- Vetrocoke), alanine, and diethyl or
dimethyl glycine (Alkacid, BASF), because it is has one amino and one
5
carboxylic acid group, all reagents have carboxyl group but Glycine has an amino
group on the other end of the carbon chain.
1.2- Research Problem:
We observe from the previous research about the CO2 absorption and reaction
kinetics has been done, by using MDEA absorbent solution or carbonate with
several promoters, such as DEA, MEA, boric acid, and piperazine, but the
determination of thereaction kinetics by promoter amine compounds such as
glycine to a MDEA solution still has not been done, therefore in this research
study absorption of CO2 intoglycine promoted MDEA solution using a wetted
wall column of laboratory scale at 1 atmospheric pressure.
1.3-Objectives of the project :
The main aim of this research is to determine kinetic data for
absorptioninto glycine promoted N‐Methyldiethanolamine
(MDEA) solution.
The effect of temperature and promoter concentration on carbon
dioxide absorption rate and carbonate .
Comparison between glycine and diethanolamine(DEA) as a
promoter.
6
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7
Chapter 2
Literature Review
2.1 The method of carbon dioxide removal:
Removal of from gases can be split up into two different methods.
Firstly, the removal with alkanolamines by which the is removed by
absorption reactions. Depending on the process requirements, several options for
alkanolamine based treating solvents with varying compositions of solutions have
been proposed. These options can be classified into four groups. 1) Amine-Water,
2) Amine-Water- Organic Solvent, 3) Amine promoted Carbonate Processes, and
4) Amine mixtures- Water/Organic Solvent. The second method is the removal of
with alkaline salts, for example sodium- or potassium carbonate. The major
processes are based on aqueous solutions of sodium and potassium compounds.
Several processes have been proposed and studied for the removal of carbon
dioxide from sour gas. the most important gas purification techniques is
absorption. It involves the transfer of carbon dioxide from the gaseous to the liquid
phase through the phase boundary. At the process of absorption of gas into liquid,
gas principally is absorbed through mechanism of diffusion (molecular &
turbulent) and convection into liquid through interface. Carbon dioxide absorption
may be physical when merely dissolved in the absorbing solvent such as water, or
it may be chemical when carbon dioxide reacts with the absorbing solution such
MDEA solutions, so there are two types of absorption, physical absorption and
chemical absorption which will discuss in this chapter.
2.2Capture technologies:
Carbon Capture and Storage (CCS) refers to the set of technologies
developed to capture carbon dioxide ( ) gas from the exhausts of power
stations and from other industrial sources, the infrastructure for handling and
transporting to use as an energy source.
There are several technologiesthatcouldbeusedfor captures, such as
absorption, adsorption, cryogenic recovery, membrane separation and chemical
8
looping combustion. Because chemical absorption has thread vantage of dealing
with low concentration, low pressure and large flux exhaust gas in large scale
industrial application; it has been regarded as one of the most promising method
to capture from flue gas.
2.2.1 Adsorption:
Is the process by which molecules of a substance, such as a gas or a
liquid, collect on the surface of another substance, such as a solid and become
attached to the surface of solid. The molecules are attracted to the surface but do
not enter the solid's minute spaces, as in absorption .Some drinking water filters
consist of carbon cartridges that adsorb contaminants. Compare absorption.
2.2.2 Membranes:
Membranes, made of polymers or ceramics, can be used to effectively
sieve out carbon dioxide from gas streams. The membrane material is specifically
designed to preferentially separate the molecules in the mixture. A range of
configurations exists either simply as gas separation devices or incorporating
liquid absorption stages. This process has not yet been applied on a large scale
and there are challenges related to the composition and temperature of the flue
gases.
Membranes are used to separate from other gases (gas separation
membranes) and to allow to be absorbed from a gas stream into a solvent
(membrane gas absorption). Other membranes being developed are facilitated
transport membranes. There are a range of membranes types for these processes.
2.2.3 Membrane Gas Absorption:
A membrane can be used with a solvent to capture the . The
diffuses between the pores in the membrane and is then absorbed by the
solvent. The membrane maintains the surface area between gas and liquid phases.
This type of membrane is used when the has a low partial pressure, such as in
flue gases, because the driving force for gas separation is small.
9
2.2.4 Gas separation membranes
The advantage of using gas separation membranes is that the equipment
is much smaller and there is no solvent involved. At the current stage of
development, the main cost is the energy required to create a large enough
pressure difference across the membrane to drive separation.
A membrane acts as a semi-permeable barrier. The passes through
this barrier more easily than other gases. In general, the rate at which a particular
gas will move through the membrane can be determined by the size of the
molecule, the concentration of gas, the pressure difference across the membrane
and the affinity of the gas for the membrane material.
2.2.5 Cryogenics separation:
Cryogenics separation separates from the flue gas stream by
condensation. At atmospheric pressure, condenses at -56.6°C .This physical
process is suitable for treating flue gas streams with high concentrations
considering the costs of refrigeration. This is also used for capture for ox fuel
process-diffusion.
2.2.6 Physical absorption:
Absorption method has been used commercially for a long time and
proved for large scale process.This involves the physical absorption of into a
solvent based on Henry’s law. Regeneration can be achieved by using heat,
pressure reduction or both. Absorption takes place at high partial pressures.
As such, the main energy requirements originate from the flue gas pressurization.
Physical absorption is therefore not economical for gas streams with partial
pressures lower than 15vol%.
2.2.7 Chemical absorption:
Chemical absorption is an absorption which is followed by chemical
reaction where the absorbed gas is reacted with the reactant in liquid phase;
10
Chemical absorption involves the reaction of with a chemical solvent to form
a weakly bonded intermediate compound which may be regenerated with the
application of heat producing the original solvent and a stream (IPCC, 2005).
The selectivity of this form of separation is relatively high. In addition, a
relatively pure stream could be produced. These factors make chemical
absorption well suited for capture for industrial flue gases.Chemical
absorption and chemical/physical adsorption are methods under consideration for
large scale capture systems.
2.3 absorption process:
Process of absorption (also called gas absorption, gas scrubbing, or gas
washing) is a mass transfer process in which a gas mixture is contacted with a
liquid (absorbent or solvent) to selectively dissolve one or more species from the
gas phase to a liquid solvent, the components transferred to the liquid phase are
referred to as solute. The separation of components in a gaseous mixture by
absorption is based on the difference in solubility of the components in a solvent
(absorbent). Gas absorption is separation processes used in the chemical industry
and for environmental control.
Absorption involves no change in the chemical species present in the
system. Absorption is used to separate gas mixtures, remove impurities, or recover
valuable chemicals. The operation of removing the absorbed solute from the
solvent is called stripping. Absorbers are normally used with strippers to permit
regeneration (or recovery) and recycling of the absorbent. Most absorption
operations are carried out in counter current flow processes, in which the gas flow
is introduced in the bottom of the column and the liquid solvent is introduced in the
top of the column.
2.4 Absorption with Chemical Reaction
Mass transfer with chemical reaction takes place whenever two phases
which are not at chemical equilibrium with one another are brought into contact .
Such phenomena are made up of a number of elementary steps , which may be
summarized as follows :
11
1-Diffusion of one reactant from the bulk of gas phase to interface between the
gas-liquid.
2-Diffusion of the reactant from the interface towards the bulk of liquid phase.
3-Chemical reaction within liquid phase.
4-Diffusion of reactant initially presents within liquid phase, and/or of reaction
product, within phase liquid itself, due to concentration gradients which are set up
by the chemical reaction.
Mass transfer processes are coupled with a chemical reaction, in order to
improve the rate and yield of the process.
gas (A) to reacts with other solvent/ reactant dissolved in liquid with rate of
reaction of rA. Consider Figure 2.3, we make mass balance of A over volume
element dv or (S.dx).
Figure 2.1 Mass Transfer of Gas into Liquid with Chemical Reaction
Rate in = Rate out + Accumulation + Reaction rate
(2.1)
(2.2)
x
interface
Gas
dv
NA+dNA
liquid
rA(x,t)
x dx
NA
).().()( dxSrdxSt
CSdNNSN A
AAAA
).().( dxSrdxSt
CSdNSNSN A
AAAA
x-DN A
AA
c
12
Diffusion flux A in liquid (Fick’s first law)
When the Equation (2.2) is divided by S.dx , and substitution value of NA we get
(2.3)
It becomes necessary to write such an equation (2.3) for each molecular species
taking part in the reaction in order to completely describe the system.
2.5 Procedures with alkanolamines
Bottoms firstly described the absorption of CO2 by tri-ethanolamine
(TEA). His patent was used for early gas-treating plants. Further research showed
that other alkanolamines could absorb CO2 as well. The most important and used
alkanolamines, shown in Figure 2.2, are
a. monoethanolamine (MEA)
b. diethanolamine (DEA)
c. methyldiethnolamine (MDEA)
Figure 2.2 Structure of alkanoamine
Figure 2.3 Structure of glycine
AAA
A rt
C
x
CD
2
2
AA
A rt
D-d
c
x
C
dx
A
13
2.5.1 Reaction mechanism of alkanolamines
To understand and clarify the absorption mechanism of CO2 by
alkanolamines there has to be discriminated between the primary, secondary, and
tertiary amines. The mechanism of the primary and secondary alkanolamines MEA
and DEA can be represented as the general equations (2.4) and (2.5).
The overall forward reaction between and primary and secondary
alkanolamnes usually has been represented as:
+ R1R2NH ↔R1R2NCOOH (2.4)
R1R2NCOOH + R1R2NH R1R2NCOO-+ R1R2NH2
+ (2.5)
In accordance with the convention used in the amine literature, MDEA is
represented as R1R2R3N, where R1 = R2 = CH2CH2OH and R3 = CH3. When
CO2 is absorbed in aqueous MDEA solutions, the following reactions may occur
in the liquid phase:
O (2.6)
The first step is bimolecular, second-order, and rate determining, while
the second step was supposed to take place instantaneously. However, this scheme
is a substantial simplification for the reaction mechanism that actually occurs.
Since 1960a large number of studies on the reaction between CO2 and
alkanolamines in aqueous solutions has been presented.
2.5.2Reaction Kinetics of carbon dioxide absorption:
When the carbon dioxide absorbed in the solution there is reactions occur
at the equilibrium as follows:
↔
(2.7)
→
(2.8)
14
→
(2.9)
𝐷𝐸𝐴 ↔ 𝐷𝐸𝐴
(2.10)
DEA
→ 𝐷𝐸𝐴
(2.11)
↔ (2.12)
(2.13)
(2.14)
Where ,
and
From equilibrium reaction above we can determine the value of
and as the following (YI dkk,2009;Mahajani and Dackwerts,1982):
(2.15)
(2.16)
And the value of , calculate from the following equations :
+
(2.17)
(Yi dkk,2009;Kent and Elsenberg,1976)
(2.18)
(Yi dkk,2009;Danckwerts and Sharma,1966)
(2.19)
(Yi dkk,2009;Kent and Elsenberg,1976)
The reaction steps which determine the rate of reaction for the reaction (2.7) :
CO2 + H2O ↔ HCO3
- + H
+ (2.20)
CO2 + OH-
↔ HCO3- (2.21)
For the solution which has PH>8 the reaction (2.18) will be ignored and
reaction (2.19)is dominant as so the rate of reaction is :
(2.22)
15
(2.23)
If we adding methyldiethanolamine promoter the reaction will be accordis(Lin
dkk,2009;Penders dkk,2013):
+MDEA+ ↔ 𝐷𝐸𝐴
(2.24)
So the reaction rate equation is:
[ 𝐷𝐸𝐴} (2.25)
The overall reaction rate equation( will be defined by:
[ (2.26)
Where velocity reaction constant overall pseudo first order
𝐷𝐸𝐴 (2.27)
= 𝐷𝐸𝐴 (2.28)
= (2.29)
So equation (2.26) to be :
[ 𝐷𝐸𝐴 (2.30)
] (2.31)
2.6 Gas-Liquid Contactors:
Gas-liquid contactors are frequently encountered in chemical process
industry. In these contactors a gas phase and a liquid phase are brought into contact
with each other and mass transfer between the gas and the liquid phase takes place.
Often, but not necessarily, the mass transfer is accompanied by the simultaneous
occurrence of a chemical reaction. A good understanding of the behavior of gas-
liquid contactors is essential for design purposes.
A variety of gas liquid contacting equipment is in use. In some of these, the gas is
dispersed in the liquid in the form of bubbles (for example, tray towers, bubble
columns, etc) in some others the liquid is dispersed in the form of droplets films in
a continuous gas phase (for example, Wetted wall column).
2.7 Carbon dioxide absorption in wetted wall column
The wetted wall column was constructed from a tube with a wall defined
surface area stand when the Liquid overflowed from the inside and formed a liquid
16
film over the outer surface of the tube. Gas entered from the bottom of the wetted
wall column and counter currently contacted the liquid film as show in the fig 2.1
Assumptions:
Conceder steady-state
Laminar flow rate of a fluid.
Velocity on x and y direction is neglected.
Diffusion on y and z is neglected.
When the film has reached the final velocity distribution, a velocity v at high x
below the surface is (Altway 2009)
(
)
⁄
⁄
⁄ (2.32)
Where = liquid film velocity , =volumetric flow rate of liquid d=, d= pipe
diameter ,g gravity velocity , =density liquid , = viscosity liquid .
At the pipe wall surface U=0 where = ( the film thickness)
Then =
⁄ (2.33)
So the equation will come
) (2.34)
The velocity of ta the surface ( is
(
)
⁄
⁄ (2.35)
Figure (2.4) velocity distribution in a wetted wall column
Us
gas
LiquidFilm
cairan
z
x
wall pipe
17
And if the high of the column is h and assume the reaction at next the surface so
the gas contact time with the film surface is :
⁄
⁄ (2.36)
If the a mount of gas absorbed is Qs per surface area unit during the
contact time (t) , the average absorption rate during time t is Q(t) /(t).assume the
film is very thin so the total surface area which opened equal as big as pipe surface
area πdh. The total absorption rate(q) inside the film become
(2.37)
The absorption rate(q) can get from the experiment ,and Q(t) can get from
the equation (2.33) and (t ) can got from equation (2.32) changed with the flow rate
change (v) or the high of column (h), so the Q(t) can determined as function time
(t)(Altway 2009).
2.8 Reaction Regimes:
For example, we consider the case of gas absorption accompanied by irreversible
chemical reaction of general order in liquid phase: A + zB P. In this case, we
assume that the reaction rate is given by the expression.
(2.38)
Reaction of this type include the first-order case (m=1, n=0) and the
second-order case ( m = 1, n =1). In the chemical absorption phenomena there are
two competitive processes we have to consider; reaction and diffusion .This is
based on the relative rate between reaction and diffusion, so it can be classified
into several regimes reaction such as: very slow reaction, slow reaction, fast
reaction, very fast reaction, and spontaneous reaction. For classification of these
reaction regimes one usually applied Hatta Number (Hikita,1963), defined as :
(2.39)
There are three reaction regimes based on the relative rate of reaction and
diffusion √M< 0.02 In this case very slow reaction compared to diffusion rate. If
the target of process is for gas absorption, hence it can be assumed that no
chemical reaction occur in film and also in bulk of the liquid, and these is no effect
n
B
m
Amn CCkr
n
B
m
AAmn
L
CCDkmk
M 1
1
21
18
of chemical reaction on the absorption rate. So the rate of absorption of gas with
very slow reaction equal to the rate of physical absorption (without reaction). If the
target of process is for chemical reaction hence this process is controlled with
chemical reaction, and process rate equal to rate of reaction. This region is referred
to as the ―very slow reaction regime‖
√M< 0.02 The reaction is too slow to have any significant influence on the
diffusion phenomena, so there is no reaction in the film and essentially no rate
enhancement will take place, but the reaction is fast enough to maintain in the bulk
of the liquid. This situation is referred to as the ―Slow Reaction Regime‖. In this
regime the chemical reaction only have the effect of keeping the concentration of
solute low (i.e. a larger driving force).
The reaction is fast enough for an appreciable fraction of the
absorbed gas to react in the film, the concentration of unreacted dissolved gas in
the bulk of the liquid will be negligible small (in the case of an irreversible
reaction). This region is referred to as the ―Fast Reaction Regime‖.
2.9 The previous work:
The process of pure carbon dioxide absorption is analyzed in aqueous
solutions of N-methyldiethanolamine (MDEA) which use by Fernando. and
Antonio (2008) The experiments were made in a stirred tank reactor with a plane
and known interface area. From the results, they deduce that the process takes
place under isothermal conditions and moderately fast regime, with second-order
kinetics. They determined a reaction order of one with respect to the amine, and an
expression for the kinetic constant valid throughout the entire range of temperature
Pawlakand Chacuk.,(2010) studied absorption rate in aqueous
methyldiethanolamine solutions was measured using a stirred cell with a flat gas-
liquid interface .The measurements were based on a batch isothermal absorption of
the gas. The kinetic experiments were conducted under pseudo-first-order regime.
The calculated initial absorption rates enabled to estimate the forward, second
order reaction rate constant of reaction with MDEA in aqueous solution.
The kinetics absorption of into aqueousblendsof2-(1-piperazinyl)-
ethylamine(PZEA)and N-methyldiethanolamine (MDEA) were studied at using a
wetted wall column absorber. The PZEA concentrations in the blends with MDEA
202.0 M
19
to see the effect of PZEA as an activator in the blends with two different total
amine concentrations Based on the pseudo-first-order condition for the
absorption, the overall second-order reaction rate constants were determined from
the kinetic measurements .The kinetic rate parameters were calculated and
presented at each experimental condition .this research done by Paul.et.al( 2010).
Deutgen, et al(2011) used two different reactors to gather information
about the kinetics of promoted potassium carbonate solutions for CO2 capture
from flue gas. A bubble reactor was used to enable the fast evaluation of a wide
range of different solutions under a defined variation of experimental parameters as
temperature and gas flow rate. Secondly a wetted wall column reactor was used to
obtain kinetic data of gas molecules on a clearly defined liquid surface. A variation
of the experimental parameters as pressure, temperature and composition of the
phases enables a process -steering in and out of chemical equilibrium.
Arunkumar and Bandyopadhyay,(2011) presents a theoretical and
experimental investigation on the absorption of into piperazine(PZ) activated
aqueous N-methyldiethanolamine (MDEA) solvent .Good agreement between the
model predicted and experimental results validates the mathematical model
developed in this work to represent mass transfer in PZ activated aqueous
MDEA.
The kinetics of absorption in aqueous solutions of MDEA +
[bmim][BF4] were investigated using stirred cell reactor where the relevant
parameters were evaluated. The rate equation of the absorption reaction was found
to be close to first order with respect to at temperatures ranging from 303
to333 K The activation energy decreased Calculated results of the enhancement
factor and Hatta number showed that the performance of absorption in the
aqueous MDEA + [bmim][BF4] solution almostobeyed the pseudo first order
regime.thisstudy was made by Ahmady and Mohamed,(2012).
In the work by Nathalie (2013) the absorption of carbon dioxide in
aqueous N-methyldiethanolamine (MDEA) and aqueous sodium carbonate with
and without carbonic anhydrase (CA) was studied in a stirred cell contactor in the
temperature range 298–333 K. Based on the results with MDEA and sodium
20
carbonate, the observed kinetics as a function of the free enzyme concentration are
described. These results were incorporated into the Proceed Process Simulator
(Arendsen et al., 2012) to determine the impacts of the kinetic benefit of CA on
commercial absorber sizing for carbon dioxide capture from flue gases.
1
Chapter 3
Research Methodology
3.1 Description of Research
This study will be conducted to determine the reaction kinetics data of carbon
dioxide absorption gas into glycine promoted MethyleDiethanolamine (MDEA)using a
laboratory scale wetted wallcolumn at atmospheric pressure and the temperature in the
interval 303.15 K ( 30° C ) - 328.15 K ( 55 ° C).
3.2 Materials and Equipment
3.2.1 Materials
The materials will used in this study are the gas mixture of carbon dioxide and
nitrogen (with a composition of 20% and 80 % N2), Methyldiethanolamine ( MDEA ),
Glycine, Sodium hydroxide ( NaOH ), Hydrochloric acid ( HCl ), Oxalic acid ( C2H2O4 ),
Aqueduct, phenolphthalein indicator and methyl orange Indicator
3.2.2 Research Equipment
The equipment used in the study is wetted wall column deviceas shown in Figure
3.1.Design of WWC refers to some previous research, such as Pacheco (2000); Bishnoi and
Rochelle (2000); Dang (2001); Cullinane and Rochelle (2004); Rochelle, (2009); Thee,
(2012) ;Rif’ah Amalia ,(2014) ; which engaged in the mass transfer, thermodynamics and
kinetics of the reaction in the process of carbon dioxide gas absorptionwith glycine and the
solvent or the Methylealkanolamine(MDEA).Wetted Wall Column composed of two coaxial
cylinders of glass, the glass with outer diameter of 8 cm and an inside glasswith outer
diameter of 4 cm. In the middle there is a tube of stainless steel with a length of 9.3 cm, an
outer diameter of 1.3 cm and a contact surface area of 37.96 cm2. Tube serves as a flow
channel solution of Methylydiethanolamine (MDEA) -glycine. Solution of
Methylediethanolamine flows in the inner tube and then overflows at the upper end of the
tube and a flowing move down to form a thin layer on the entire surface of the tube, while the
flow of carbon dioxide gas flows from the bottom to the top and comes in contact with a thin
layer ofMethyediethanolamine solution in the entire outer surface of the tube . Annulus side
between the two cylinder glass serves for heating the flow from Water Bath Thermostat as
regulator mediaof temperature system stabilityinWWC.
2
Figure 3.1 Wetted Wall column
FI
T3
T2
T1
C
P1
P2
T4T5
T6
V3
V1
V2
R1R2
TC
TT
TT
Larutan
keluar
Larutan
masukGas
masuk
Gas
keluar
Air
panas
masuk
Air panas
keluar
WWC
FI
Figure 3.2 Experimental set up
Output of gas
Input of gas
Input of hot water Output of MDEA solution-promoter
Output of MDEA solution
_promoter-
Output of hot water
Out
put of
gas
Output of hotwater
Output
of
solution
input of
hotwater
input
of gas
input
of
liquid
3
Caption:
C: coil of heater
P1: Pump of MDEA solution with promoter
P2: Water Pump
R1: Rotameters of liquid
R2: Rota meters of gas
T1: Waterbath
T2: Tank reservoir (MDEA solution tank with promoter )
T3: Tank of overflow
T4: Feed tank of gas ( )
T5: Tube saturator
T6: Tank of samples
TT: Thermo transmitter
TC: Thermo control
V1: Gate valve solution
V2: Gate valve
V3: Gate valve (bypass)
WWC: wetted wall column
3.3 Operating Conditions and Research variables :
The operating conditions and the variables will used in this study are :
•Operating conditions:
1. Pressure: 1 atmosphere
2. Temperature:
30, 35, 40, 45, 50, 55 C
• Gas feed
1. Type of gases feed: a mixture of 20 % + 80 % N2
2. The gas flow rate: 6 L / min
• Solvents
1. Type of solvent: MDEA
2. The concentration of solvent: 30 % by weight
3. The solvent flow rate: 200 mL / min
• Promoters
4
1. Type of promoter: glycine
2. The concentration of promoter: 1-3 % (wt. %) Glycine
3.4 Research Procedure
1. Preparation of research material equipment:
a. Prepare a research materials, such as a gas mixture of carbon dioxide and nitrogen,
Methylediethanolamine (MDEA), glycine, distillation water, PhPh indicator, the indicator of
MO, hydrochloric acid, oxalic acid, and sodium hydroxide.
b. Preparing research equipment, such as Methyldiethanolamine solution tank, a tank of
samples, burette, the stand, Erlenmeyer, flask, measuring cup, funnel glass, volume pipette,
and pipette.
c. Stringing of wetted wall column equipment as Figure 3.2
d. Preparing the titration equipment which used for the solution analysis.
2. Operation procedure:
a. Fill water into the water bath (T1) as a regulator of temperature in the WWC jacket.
b. Creating Methyldiethanolamine solution of 30% by weight.
c .Each adding of glycine (wt%) in accordance with the variable to a solution of MDEA 30%
by weight, and for pure MDEA will not added glycine promoter.
d. MDEA solution with the promoter enter into the reservoir tank (T2).
e. Setting the operating temperature in accordance with the variable.
f. Circulate hot water in the annulus side column of WWC and returned to the water bath
(T1).
g. circulating MDEA solution with promoter by using the pump from the reservoir tank (T2)
to the overflow tank (T3) until the solution overflow.
h. Adjusting the flow rate of MDEA solution with the promoter, so the solution flows from
the bottom to up through the inside of the tube to form a thin film on the tube surface.
i. When the temperature has reached the desired system and the flow has stabilized, a mixture
of carbon dioxide and nitrogen gas flowed through the saturator tank (T5).
j. Then a mixture of carbon dioxide and nitrogen gas flows from the bottom of the column to
the top of the column outer stainless steel pipe so that it contacts between carbon dioxide and
nitrogen gas with a thin layer of fluid around the outer surface of the tube until steady state
conditions.
5
k. If achieved steady state conditions, taking samples of MDEA solution with promoter from
the sample reservoir tank (T6),for analysis using the content of carbonate and bicarbonate
using a titration method by using phenolphthalein and a methyl orange indictor.
3. Analysis of the samples
Analysis of the content of carbonate and bicarbonate
Analysis of the initial and final concentration content of carbonate and bicarbonate
will conducted by titration using phenolphthalein and methyl orange indicators.
3.5 Data Evaluation:
Based on data from experimental results and some of the literature can be calculated
to determine the reaction rate constants of promoter with the following stages:
Calculation of gas - liquid contact time (Danckwerts, 1970):
*
+
⁄
*
+
⁄
(3.1)
The calculation of the amount of gas absorbed per unit surface area for contact time
( t ) , then the average rate of absorption during t is Q ( t ) / t is (Danckwerts , 1970) :
(3.2)
Where
[ ]
Calculation of[ ] and[ ] of the equilibrium reaction using equation ( Yi et al , 2009) :
[ ]
[ ]
[ ]
(3.3)
[ ]
[ ]
[ ]
(3.4)
The value of , and obtained from the following equation :
(
) (3.5)
(Yi dkk, 2009)
3.6)
(Yi dkk, 2009)
(
)(3.7)
(Yi dkk, 2009)
(
) (3.8)
The calculation of the value of obtained by trial kov , using equation ( Altway , 2009)
6
√
√ (3.9)
After values obtained from equation (3.9), then the value kov can be determined from
equation (Danckwerts, 1970)
√ (3.10)
Determining the kapp valuefromthe followingequation:
kapp = kov - kOH- [OH-] – kMDEA [MDEA] (3.11)
where
kapp= kglycine [glycine] (3.12)
the value of can get from following equation(Lin dkk, 2009) :
(3.13)
The reaction rateconstant of glycine (kglycine)is a function of temperaturere presented by the
Arrhenius equation:
(3.14)
description:
1.The reaction conditionsin the absorptionof carbon dioxidein MDEA solution with
promotergenerallybeenin the regime ofrapid reactionwith the provisions ofpseudofirst
orderby the value of3 < Ha < ½ Ei, where (Danckwerts, 1970; Lin dkk, 2009) :
√
(3.15)
√
√
(3.16)
2.the mass transfer coefficient of gas (kg) can be obtained from this equation (Cullinane dan
Rochelle, 2004) :
(3.17)
Where
(3.18)
(3.19)
(3.20)
3.the mass transfer coefficient of liquid (kL) can obtained from this equation :
√
(3.21)
7
4. The diffusivity coefficient of liquid ( ) can obtained fromWilke Chang equation (Wilke
dan Chang, 1955):
√
(3.22)
And the diffusivity coefficient of gas obtained from the table 6.2-1 (Geankoplis 3rd
edition1993) and make the temperature correction from :
(
)
(3.23)
The solubility can be got from the henry constant equation:
.
⁄ (
)/ (3.24)
(Amalia.R, 2014)
8
Chapter 4
Results and Discussions
This chapter shows the results obtained for this study on the reaction kinetics data of carbon
dioxide absorption into glycine promoted Methyldiethanolamine (MDEA) using laboratory
scale wetted column equipment at atmospheric pressure by varying temperatures from 303.15
to 328,15 , the solvent content 30% wt. MDEA, glycine concentration (1%-3% wt.) , and the
gas phase contains 20% Carbon dioxide and 80% Nitrogen. The reaction kinetic data was
obtained from the carbon dioxide absorption rate data.
4.1The effect of temperature and concentration of promoter oncarbon dioxide
absorption rate
The effect of temperature and promoter (glycine) concentration on carbon dioxide absorption
rate was shown in Figure 4.1-a and Figure 4.1-b. The carbon dioxide absorption rate tends to
increase with increasing of temperature. These figures also indicate that the addition of
glycine as promoter can significantly enhance the absorption rate, because it is has one amino
and one carboxylic acid group.
Figure 4.1-a:
The effect of temperature and promoter concentration on carbon dioxide absorption
rate.
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
300 305 310 315 320 325 330
Ab
sorp
tio
n r
ate
of
Co
2 *
10
^5(k
mo
l/s)
T(K)
glycine 1%
glycine 2%
glycine 3%
MDEA-pure
9
Figure 4.1-b :The effect of temperature and promoter concentration on carbon dioxide
absorption rate.
The fact that the absorption rate is enhanced by increasing of temperature can be explained
by that increasing temperature will cause incrementof kinetic energy of substances molecules
so that the reaction will be faster,.in addition a higher temperature resulting in a higher
diffusivity ( Lin , 2009). And also increasing of promoter concentration from (1 -3%
wt.)will enhancethe reaction rate significantly.
4.2The effect of temperature and concentration promoter on outlet concentration of
carbonate:
The chemical absorption of carbon dioxide into Glycine promoted MDEA solution will
produce carbonate and bicarbonate, and a further absorption will raise their concentration in
the solution. In this study the absorption rate was estimated by measuring the carbonate and
bicarbonate concentration in the outlet solution. Figure (4-2) show that increasing of both
temperature and promoter concentration from (1%-3%wt) will cause increment in carbonate
concentration.
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
1 2 3 4 5 6
Ab
sorp
tio
n r
ate
of
Co
2 *
10
^5(k
mo
l/s)
T(K)
glycine 1%
glycine 2%
glycine 3%
MDEA-pure
10
Figure 4.2 : The effect of temperature and concentration of promoter on carbonate
outlet concentration.
The promoter concentration has a considerable effect on the contact time between gas
and liquid , increasing promoter concentring will increase the contact time consequently
carbonate concentration in the liquid stream.
4.3 Carbon dioxide recovery :
Table 4.1: Carbon dioxide recovery
Temp
(K)
CO2 recovery %
glycine
(1% w/v)
glycine
(2% w/v)
glycine
(3% w/v)
303.15 3.482054 3.97949 4.642738
308.15 3.792305 4.466493 4.88786
313.15 4.110761 4.795888 5.052811
318.15 4.52443 5.04648 5.307505
323.15 4.860662 5.302541 5.656044
328.15 5.205099 5.653815 6.012787
0
2
4
6
8
10
12
14
16
18
20
300 310 320 330
ou
tlet
co
nce
ntr
atio
n o
f C
arb
on
ate(
kmo
l/m
3)
T (K)
glycine 1%
glycine 2%
glycine 3%
MDEA-pure
11
4.4 Reaction rate constant:
Correlation of reaction rate constant has been developed from the results obtained in this
research and isfeatured in two model that is glycine promoter reaction rate constant (k
glycine) and apparent reaction rate constant (kapp).
4.4.1 Glycine promoter reaction rate constant:
From the experiment results, literature and calculation ,an overall reaction rate
constant is obtained .the gained results is shown in the fig(4-3) the method used is trial and
error in equation (3.9) and (3.10).in this fig it observed that when the promoter concentration
and temperature increase the overall constant rate will increase. This isdue the fact that
reaction rate constant is influenced by both temperature and promoter concentration.
Figure 4.3: The effect of temperature and promoter concentration on overall reaction
rate constant.
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
300 305 310 315 320 325 330
kov(
S-1)
x 1
0^9
T(K)
glycine 1%
glycine 2%
glycine 3%
y = -3251.9x + 31.609 R² = 0.9896
20.7
20.8
20.9
21
21.1
21.2
21.3
21.4
21.5
21.6
21.7
21.8
0.003 0.00305 0.0031 0.00315 0.0032 0.00325 0.0033 0.00335
ln(
kgly
cin
e)(m
3/k
mo
l.s)
1/T(K)
12
Figure 4.4: The effect of temperature and concentration of promoter on promoter
reaction rate constant.
Reactivity of glycine as a promoter in the absorption of carbon dioxide can be
examined from the reaction rate constants which can be correlatedusing Arrhenius equation k
=A*exp (-E/RT).
Figure 4-4, we obtained intercept for glycine that is ln A = 31.609 and the slope is (-
E / R) = 3251.9, so the equation kglycine = 5.3409E+13exp (-3251.9 /T).
From the obtained equation the regression value is 0.9896 for glycine promoter and
the activation energy is 27.0363kJ/kmol.
Fig (4-4) showed that a low value of Lnk is obtained at high value of 1/T .
4.4.2 Apparent Reaction Rate Constant (kapp):
From experiment calculation, acorrelation for reaction rate constant apparent isalso
obtained (reaction rate constant of glycine promoter)as a function of temperature by using
equation (3.11).the relation between temperature and ln kapp is shown in fig(4.5)
Figure 4.5: The effect of temperature and concentration of promoter on apparent
reaction rate constant (kapp).
The reaction rate constant apparent as function of temperature is expressed by
Arrhenius equation:
Kapp=A*exp (-ER/T)
By:
[ ]
20
20.2
20.4
20.6
20.8
21
21.2
21.4
0.003 0.00305 0.0031 0.00315 0.0032 0.00325 0.0033 0.00335
ln k
app
(S-1
)
1/T(K)
glycine 1%
glycine 2%
glycine 3%
13
[ ]
.
4.5 Comparison between k glycine and another rate constant promoter:
The reaction rate constant for CO2 absorption using Glycine obtained in this study is
compared with other reaction rate constantsof different solvents from literature and is shown
in Table (4.1) and Figure (4.6).
It observed that glycine has the highest reaction rate constant comparing to the other.
Table 4.2 Comparison of reaction rate constant of carbon Dioxide for several solvent
promoter Value of k (L/mol.s) Referens
Glycine
This study
MEA
Aboudheir, 2006
MDEA
Aboudheir, 2006
DEA
Chih-et.al (2009)
PZER
Pual.S et.al(2009)
AMP
Yu-Ming.H.et.al(2011)
14
Figure 4.6: Compression of k glycine with another rate constant promoter
4.6 Comparison between glycine promoted MDEA and DEA promoted MDEA:
For the comparison an experiment has been done to determine kinetics data of
carbon dioxide absorption into diethanolamine(DEA) instead of glycine promoted
methyldiethanolamine (MDEA) by using laboratory scale wetted column equipment at
atmospheric pressure by varying temperatures from 303.15 to 313,15 , the solvent content
from 1 mol/l MDEA, and DEA concentration is (0.1, 0.2, 0.3 mol/l) the mixer of gas content
from 20% carbon dioxide and 80% nitrogen.
4.6.1 The rate of carbon dioxide absorption:
Figure (4.7) show that when diethanolamine wasused as the promoter instead of
glycine .the carbon dioxide Absorption rate increase when the concentration of the promoter
increase however it decrease when the temperature increase .
0
5
10
15
20
25
0.003 0.0031 0.0032 0.0033 0.0034
ln k
(m3/k
mo
l.s)
1/T(K)
k MEA-Aboudheir,2006
k MDEA-Aboudheir,2006
kglycine-This study
k DEA-Chih -et.al(2009)
k PZEA-Pual.S.et.al(2009)
15
Figure 4.7: Comparison of temperature effect on carbon dioxide absorption rate for
glycine and DEA for this study
4.6.2 The reaction rate constant:
From experimental result, acorrelation for reaction rate constant is obtained for
glycine and DEA, it observed that glycine reaction rate constant is larger than DEA reaction
rate constant as shown in figure (4.8), because Glycine has one amino and one carboxylic
acid group however DEA is an organic compound belongs to the secondary group with the
formula acts as weak base, reflecting the hydrophilic character of the secondary amine and
hydroxyl groups
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
302 304 306 308 310 312 314
CO
2 a
bso
rpti
on
rate
(km
ol/
s)
T(K)
glycine 1%
glycine 2%
glycine 3%
DEA 0.1 mol/l
DEA 0.2 mol/l
DEA 0.3 mol/l
0
5
10
15
20
25
0.003 0.00305 0.0031 0.00315 0.0032 0.00325 0.0033 0.00335
Ln k
(s-1
)
1/T(K)
K DEA
K glycine
16
Figure 4.8: Comparison of glycine and DEA rate constant using MDEA
4.6.3 DEA constant rate for this study and previous study:
The correlation of reaction rate constant is:
For this study:
k DEA=
For Chih-et.al (2009) study:
k DEA=
For Zhang et.al (2003) study:
Lnk DEA=24.515-5411.3/T
Figure 4.9: Comparison of DEA constant rate between this study and previous work
0
1
2
3
4
5
6
7
8
9
10
0.003 0.0031 0.0032 0.0033 0.0034
Ln k
(s-1
)
1/T(K)
k DEA- this study
k DEA-Chih et.al(2009)
k DEA-Zhang et.al(2003)
17
Figure 4.10: Comparison of kov constant rate for this study with previous study using
MDEA solvent
0.0
2.0
4.0
6.0
8.0
10.0
12.0
302 304 306 308 310 312 314
k o
v x
10
^9(s
-1)
T(K)
0.1 mol/l AMP
0.2 mol/l AMP
0.3 mol/l AMP
0.1 mol/l DEA
0.2 mol/l DEA
0.3 mol/l DEA
1%glycine
2% glycine
3% glycine
18
Appendix A
A.1 Determination of Steady State
Steady state is a condition in which there is no change in the concentration and is not
affected by time. Based on research obtained each time such a relationship with
concentrations obtained as follows:
Table A.1 Volume Data of HCl in The titration Method
Time (minute) Volume of HCl
(mL)
0 0
1 7.4
2 7.3
3 7.4
4 7.5
5 7.8
6 7.2
7 7.2
8 7.2
9 7.2
10 7.2
So it can be graphed the relations between HCl volume and the time as follows:
Figure A.1 The readings of Steady State
based on Figure A.2 can be seen that the steady state is achieved at time t = 6 minutes. So
that sampling in this study conducted at t = 6 minutes.
0
1
2
3
4
5
6
7
8
9
0 1 2 3 4 5 6 7 8 9 10
V of
HC
L
(ml)
Time (min)
19
A.2 Data Analysis
Here is an example of the calculation of the variable experimental results for glycine
promoter concentration (1% w / w). Solvent flow rate 200 ml / min and temperature 30oC
(303.15 K)
Analysis of The first Solution:
A mixture of MDEA solvent , glycine and distilled water can be made by calculation,
for example:
Base : 2000g
MDEA(30%) :600 g
Glycine(1%) :20 g
Aqueduct :1380 g
Total :2000 g
To analyze the content of carbonate and bicarbonate for initial solution, by titration using
hydrochloric acid (HCl) with the PhPh and MO indicator. The first titration to determine the
content of carbonate in initial solution as follows:
Volume of the solution sample : 5 mL
Molarity of HCl : 1 M
Volume of HCl (VHCl)PhPh : 7 mL
From the titration result can be calculate the mole of initial carbonate in 10 ml of solution
sample are::
[CO32-
]initial =
=
= 14 mmol/mL
The second titration to determine the content of initial bicarbonate as follows:
Volume of the solution sample : 5 mL
Molarity of HCl : 1 M
Volume of HCl (VHCl)PhPh : 7 mL
Volume of HCl (VHCl)MO-PhPh : 0 mL
From the titration result can be calculate the mole of initial bicarbonate in 10 ml of solution
sample are::
:
[HCO3-]initial =
=
= 0 mmol/mL
Final Solution Analysis :
To analyze the content of carbonate and bicarbonate for final solution, by titration using
hydrochloric acid (HCl) with the PhPh and MO indicator. The first titration to determine the
content of carbonate in final solution as follows:
20
Volume of the solution sample : 5mL
Molarity of HCl : 1 M
Volume of HCl (VHCl)PhPh : 7.1 mL
From the titration result can be calculate the mole of final carbonate in 10 ml of solution
sample are:
Mol CO32-
final =
=
=14.2mmol/mL
The second titration to determine the content of initial bicarbonate as follows:
Volume of the solution sample : 5 mL
Molarity of HCl : 1 M
Volume of HCl (VHCl)PhPh : 7.1 mL
Volume of HCl (VHCl)MO : 11.2 mL
Volume of HCl (VHCl)MO-PhPh : 4.1
From the titration result can be calculate the mole of final bicarbonate in 10 ml of solution
sample are::
:
MolHCO3-final=
=
= 8.2 mmol/mL
Determining of gas carbon dioxide concentration dissolved [CO2]e and [OH-] concentration
.
/
.
/
where :
T = 30 oC = 303.15 K
[CO32-
]average =
=
[HCO3-] =
And K1 = 4.6950 x 10-7
kmol/m3, Kw = 1.264 x 10
-14 kmol
2/m
6, k2 = 5.156 x 10
-11 kmol/m
3.
So the concentration of CO2 dissolved at temperature 303.15 K is :
[ ]
[ ]
[ ]
=
=5.23702E-04 kmol/m3
To determine the carbon dioxide gas absorption rate:
Solvent flow rate (v) = 200 ml/min
21
= 3.33 x 10-6
m3/min
[CO32-
] initial = 14 kmol/m3
[CO32-
] final = 14.2kmol/m3
[ ] initial = 0kmol/m
3
[ ] final = 8.2kmol/ m
3
So the absorption rate of carbon dioxide gas is:
q= v x [([CO32-
]final - [CO32-
]initial)+( [ ]final-[
]initall)]
= (3.33 x 10-6
m3/min) x [{(14.2 kmol/m
3) –(14kmol/m
3)}+{(8.2kmol/m
3 )-(0 kmol/m
3)}]
= 2.79972E-05 kmol/s.
Contact time
*
+
⁄
*
+
⁄
where,
h = 0.093
solution = 0.000589283 kg/m.s
g = 9.8 m/s2
solution = 1163 kg/m3
d = 0.013 m
v = 200 ml/minute ⁄
= 3.14
the contact time between solution and gas is :
0 (
)
(
)(
)1
⁄
*
+
⁄
=
0.176965775 s
The average absorption rate at time t:
where,
q = 2.79972E-05 kmol/s
h = 0.013 m
d = 0.093 m
so the absorption rate average during t time (Q(t)/t)is :
= 0.007374943kmol/m2
Henry constant :
Henry constant can be obtained from this equation :
22110
log IhIhHe
He
22
Where , He0
is henry constant for gas –liquid system and I is ionic force from the solution
which can be get from :
He298 exp[
-
)] where
T = 30 oC = 303.15 K
∑
Ci is ion concentration – ion valence is Zi.
h = h+ + h- + hG
hG= hG,o+ hT(T-298.15)
for MDEA solution we got
ΣI*h= 1.21232768
(298)=0.036 (mol//dm
3.atm)
-dlnkH/d(1/T) =2200 K
so, the Henry constant will be:
exp(2200*(1/303.15-1/298))
= 3.19E-05 mol/cm3.atm
= 3.18E+6 m3.Pa/kmol
= 5.18E+7 m3 m
3.Pa/kmol
Diffusivity CO2 and CO32-
- Diffusivity CO2 and CO32-
into water can be calculate by using Wilke
Chang (Wilke and Chang, 1955) as follow :
√
where, = association parameter from solvent (water = 2.6)
MB = molecular weight of solvent (kg/kmol)
T = operation temperature (K)
= solvent viscosity (kg/m.s)
VA = molar volume solute (m3/kmol)
√
=
√
(
)
= 1.19085 x 10-9
m2/s
*By the same method DBL (CO32-
-H2O) = 1.04496 x 10-9
m2/s
- Diffusivity of CO2 into N2 gas is obtained from table 6.2-1 (Geankoplis,1993) at
temperature
298 K = 0.167 x 10-4
m2/s, so :
.
/
23
The diffusivity of CO2into N2 gas (DAG) at temperature 303.15 K is :
(
) (
)
( ) (
)
( ) m2/s
Mas transfer coefficient of Gas (kG)
kg =
where
Sc = Schmidt number =
=
= 1.376134927
v =
=
where QG (gas flow rate ) = 6 L/min = 0.0001 m3/s
Re =Reynolds number
=
=
= 414.1614516
Sh = Sherwood number
=
=
= 44.41256902
so
kg =
= 2.33051 x 10^(-8) kmol/s.m2.Pa
Mas transfer coefficient of liquid (kL)
kL = √
where
Г = liquid-flow rate, (kg/m.s) based on wetted perimeter
= liquid density, (kg/m3)
h = high contact area, (m)
= liquid viscosity , (kg/m.s)
g = gravity acceleration, (9.80665 m/s2)
24
kL = mas transfer coefficient , (kmol/s.m2)
Г =
=
BF = ,
-
⁄
BF = 2 (
)
3
⁄
= 1.7709514 m
So,
kL =0.422√
= 0.000732019 kmol/s.m2
CO2 concentration at Interface (CAi) and Overall Pseudo constant reaction rate First
Order (kov) √
√ ………. (a)
√ ………..(b)
where,
kg = mas transfer coefficient of the gas, (kmol/s.m2.Pa)
PA = partial pressure of the gas CO2, (Pa)
CAe = gas CO2 concentration equilibrium with the liquid,(kmol/m3)
DAL = gas CO2 diffusivity coefficient (m2/s)
He = Henry constant , (Pa.m3/kmol)
φ = √
Substitute equation (a) (b)
(
)
= (
)
= (
)
φ =
= 1.17 m/s
So,
φ = √
φ2 =
= φ2/
= (-1.17 m/s)2/1.19085 x 10
-9 m
2/S = 5.2E+8 S
-1
25
√
√
(
) ( )√(
)
(
)(
) √(
)
= 0.00683 kmol/m3
apparent reaction rate constant (kapp)
=
= 12169.4834 m3/kmol.s
[OH-] =
[ ]
[ ]
=
= 0.000421557 kmol/m3
1% glycine concentration into 1000 g solution MDEA can be obtained as:
Mw of glycine = 75.07 g/mol
sol. = 1163 kg/m3
V = 859.845x10
-6m3
= 0,86L
Mole of glycine=10/75.05 = 0.133mol
Molarity of glycine = 0.133mol/0.86 = 0.15465 mol/liter
kMDEA =2*10^9*exp(-5797.8/T)
T=303.15
kMDEA=9.88706627
kapp = kov - kOH- [OH-]-kMDEA[MDEA]
= (5.2E+8) – {(12169.4834 ) x (0.000421557)} - (9.88706627*2.927922)
= 5.2E+8 s-1
26
APPENDIX B
B.1 Analysis Result by using Titration method :
Table B.1 Calculation Data for [CO32-
] and [HCO3-] by Glycine Promoter at Concentration
1% wt
T (K) MolarHC
l (M)
Vol
HCl
(phph
)
Vol
HCl
(mo
)
[CO32-
]
first con
(mmol/mL
)
[HCO3-]
(mmol/mL
)
[CO32-
] last
con
(mmol/mL
)
[CO32-
]
average
(mmol/mL
)
303.1
5
1 7.1 11.2 14 8.2 14.2 14.1
308.1
5
1 7.3 11.5 14 8.4 14.6 14.3
313.1
5
1 7.5 11.8 14 8.6 15 14.5
318.1
5
1 7.8 12.2 14 8.8 15.6 14.8
323.1
5
1 8.1 12.5 14 8.8 16.2 15.1
328.1
5
1 8.4 12.8 14 8.8 16.8 15.4
Table B.2 Calculation Data for [CO32-
] and [HCO3-] by Glycine Promoter at Concentration
2% wt
T (K) Molar
HCl (M)
Vol
HCl
(phph)
Vol
HCl
(mo)
[CO32-
]
first con
(mmol/mL)
[HCO3-]
(mmol/mL)
[CO32-
] last
con
(mmol/mL)
[CO32-
]
average
(mmol/mL)
303.15 1 7.7 11.8 14 8.2 15.4 14.7
308.15 1 7.9 12.3 14 8.8 15.8 14.9
313.15 1 8.2 12.6 14 8.8 16.4 15.2
318.15 1 8.3 12.8 14 9 16.6 15.3
323.15 1 8.4 13 14 9.2 16.8 15.4
328.15 1 8.5 13.3 14 9.6 17 15.5
27
Table B.3 Calculation Data for [CO32-
] and [HCO3-] by Glycine Promoter at Concentration
3% wt
T (K) Molar
HCl (M)
Vol
HCl
(phph)
Vol
HCl
(mo)
[CO32-
]
first con
(mmol/mL)
[HCO3-]
(mmol/mL)
[CO32-
] last
con
(mmol/mL)
[CO32-
]
average
(mmol/mL)
303.15 1 8.1 12.6 14 9 16.2 15.1
308.15 1 8.2 12.8 14 9.2 16.4 15.2
313.15 1 8.2 12.9 14 9.4 16.4 15.2
318.15 1 8.3 13.1 14 9.6 16.6 15.3
323.15 1 8.5 13.4 14 9.8 17 15.5
328.15 1 8.7 13.7 14 10 17.4 15.7
Table B.4 Calculation Data for [CO32-
] and [HCO3-] at pure MDEA
T (K) Molar
HCl (M)
Vol
HCl
(phph)
Vol
HCl
(mo)
[CO32-
]
first con
(mmol/mL)
[HCO3-]
(mmol/mL)
[CO32-
] last
con
(mmol/mL)
[CO32-
]
average
(mmol/mL)
303.15 1 7 11.1 14 8.2 14 14
308.15 1 7 11.2 14 8.4 14 14
313.15 1 7.1 11.6 14 9 14.2 14.1
318.15 1 7.2 11.8 14 9.2 14.4 14.2
323.15 1 7.3 11.9 14 9.2 14.6 14.3
328.15 1 7.5 12.2 14 9.4 15 14.5
28
B.2 The Value of Henry Constant
Table B.5 Calculation Data for Henry Constant at the variable of temperatures
T(K) (-d ln Kh /
d(1/T))
((1/T)-
(1/298))
EXP((-d ln Kh /
d(1/T)) x ((1/T)-
(1/298))
He298 He˚t(mol/cm3.atm)
He˚t
(m3.pa/kmol)
303.15 2200
2200
2200
2200
2200
2200
-5.53E-05 0.885411541 0.000036
0.000036
0.000036
0.000036
0.000036
0.000036
3.19E-05 3.18E+06
308.15 -1.09E-04 0.787055915 2.83E-05 3.58E+06
313.15 -1.61E-04 0.702261834 2.53E-05 4.01E+06
318.15 -2.11E-04 0.628852251 2.26E-05 4.48E+06
323.15 -2.59E-04 0.565043676 2.03E-05 4.98E+06
328.15 -3.07E-04 0.509367738 1.83E-05 5.53E+06
B.3 The Value of Diffusivity
Table B.6 Calculation of Diffusivity
T (K) DAL(CO2->H2O)
(m2/s)
DAG(CO32-
->N2) (m2/s)
DAL(CO32-
-
>H2O) (m2/s)
303.15 2.310x10-9
1.719x10-5
1.044x10-9
308.15 2.601x10-9
1.769x10-5
1.062x10-9
313.15 2.913x10-9
1.819x10-5
1.079x10-9
318.15 3.241x10-9
1.870x10-5
1.096x10-9
323.15 3.589x10-9
1.922x10-5
1.113x10-9
328.15 3.953x10-9
1.975x10-5
1.131x10-9
29
B.4 The value of Mass Transfer Coefficient:
Table B.7 Calculation of Mass Transfer Coefficient for The gas at temperature 303.15 K -
328.15K
T
(K) Sc Re Sh
kg
(kmol/s.m2.Pa)
303.15 1.376134927 414.1614516 44.41256902 2.33051E-08
308.15 1.290799952 429.0804249 43.34487987 2.30256E-08
313.15 1.213683613 443.6691457 42.31943061 2.27539E-08
318.15 1.143756121 457.9226645 41.33391503 2.24896E-08
323.15 1.080141657 471.8385795 40.38618648 2.22325E-08
328.15 1.02209215 485.4166579 39.47424451 2.19822E-08
Table B.8 Calculation of Mass Transfer Coefficient for The liquid at Temperature 303.15
K -328.15K and MDEA 30% Concentration with the glycine promoter (1; 2; 3 %wt)
Temp
(K)
KL (kmol/s.m2)
glycine
(1% w/v)
glycine
(2% w/v)
glycine
(3% w/v)
303.15 0.000732019 0.000725222 0.000728495
308.15 0.000788328 0.000785579 0.000789155
313.15 0.000847041 0.000848722 0.000852615
318.15 0.000908155 0.00091466 0.000918883
323.15 0.000971667 0.000983397 0.000987964
328.15 0.00103757 0.001054936 0.001059861
30
Table B.9 Calculation of Mass Transfer Coefficient for The liquid at Temperature 303.15
K -328.15K with pure MDEA 30% Concentration
Temp (K) KL (kmol/s.m2)
303.15 0.000730106
308.15 0.000786323
313.15 0.000844945
318.15 0.00090597
323.15 0.000969396
328.15 0.001035216
31
B.5 Absorption Rate, time of CO2Absorption Contact and CAe
Table B.10 The Calculation of Absorption Rate, The Time of Contact and CAe at Temperature 303.15 K – 328.15 K with MDEA 30%
Concentration with glycine promoter (1; 2; 3 % wt)
Temp
(K)
Absorption Rate, q (kmol/s) Time of Contact (s) CAe (mmol/mL)
glycine glycine glycine glycine glycine glycine glycine glycine glycine
(1% w/v) (2% w/v) (3% w/v) (1% w/v) (2% w/v) (3% w/v) (1% w/v) (2% w/v) (3% w/v)
303.15 0.0000279972 0.0000319968 0.0000373296 0.176965775 0.178624244 0.177821842 0.000523702 0.000502326 0.000589092
308.15 0.0000299970 0.0000353298 0.0000386628 0.172533247 0.173137023 0.172352559 0.000570688 0.000601112 0.000644033
313.15 0.0000319968 0.0000373296 0.0000393294 0.168354327 0.168020775 0.167253742 0.000616767 0.000616047 0.000702917
318.15 0.0000346632 0.0000386628 0.0000406626 0.164409122 0.163239866 0.162489711 0.000659533 0.000667308 0.000759249
323.15 0.0000366630 0.0000399960 0.0000426624 0.160679682 0.158763056 0.158029197 0.000674 0.000722315 0.000814314
328.15 0.0000386628 0.0000419958 0.0000446622 0.157149777 0.154562845 0.153844689 0.000690717 0.000816707 0.000874895
32
Table B.11 The Calculation of Absorption Rate, The Time of Contact and CAe at
Temperature 303.15 K – 328.15 K with pure MDEA 30% Concentration
Temp
(K)
Absorptio
n Rate, q
(kmol/s)
Time of
Contact (s)
CAe
(mmol/mL)
303.1
5
2.73306E-05 0.00019286
8
0.00052744
2
308.1
5
2.79972E-05 0.00018802
4
0.00058291
7
313.1
5
3.06636E-05 0.00018345
7
0.00069463
7
318.1
5
3.19968E-05 0.00017914
6
0.00075131
2
323.1
5
3.26634E-05 0.00017507 0.00077787
7
328.1
5
3.46632E-05 0.00017121
2
0.00083703
4
B.6 Calculation of CO2 Concentration at The Interface (CAi) and Overall
Reaction velocity Constant Pseudo First Order (kov)
Table B.12 The Value of CAi and kov at Temperature 303.15 K – 328.15 K with
MDEA 30% Concentration with glycine promoter (1%wt)
T (K) P (Pa) CAi φ kov
303.15
20265.000
6.83E-03 1.17E+00 5.20E+08
308.15 6.46E-03 1.34E+00 6.20E+08
313.15 6.13E-03 1.53E+00 7.33E+08
318.15 5.89E-03 1.75E+00 8.71E+08
323.15 5.74E-03 1.91E+00 9.51E+08
328.15 5.61E-03 2.07E+00 1.03E+09
33
Table B.13 The Value of CAi and kov at Temperature 303.15 K – 328.15 K with
MDEA 30% Concentration with glycine promoter (2%wt)
T (K) P (Pa) CAi φ kov
303.15
20265.000
7.44E-03 1.22E+00 5.61E+08
308.15 6.74E-03 1.52E+00 7.92E+08
313.15 6.50E-03 1.67E+00 8.75E+08
318.15 6.06E-03 1.89E+00 1.02E+09
323.15 5.70E-03 2.12E+00 1.17E+09
328.15 5.32E-03 2.45E+00 1.44E+09
Table B.14 The Value of CAi and kov at Temperature 303.15 K – 328.15 K with
MDEA 30% Concentration with glycine promoter (3%wt)
T (K) P (Pa) CAi φ kov
303.15
20265.000
7.68E-03 1.39E+00 7.29E+08
308.15 7.08E-03 1.58E+00 8.64E+08
313.15 6.50E-03 1.79E+00 1.00E+09
318.15 6.07E-03 2.02E+00 1.16E+09
323.15 5.75E-03 2.28E+00 1.35E+09
328.15 5.49E-03 2.55E+00 1.56E+09
34
B.7 The Values kglycine
Table B.15 the Calculation of kglycine at Temperature 303,15 K – 328,15 K with
MDEA 30% Concentration with the glycine promoter (1; 2; 3 % wt)
Temp
(K)
kglycine (s-1
)
glycine
(1% w/w)
glycine
(2% w/w)
glycine
(3% w/w)
303.15 3.36E+09 1.81E+09 1.57E+09
308.15 4.00E+09 2.56E+09 1.86E+09
313.15 4.73E+09 2.82E+09 2.15E+09
318.15 5.62E+09 3.28E+09 2.50E+09
323.15 6.14E+09 3.79E+09 2.91E+09
328.15 6.64E+09 4.66E+09 3.35E+09
Conclusion
From the data calculation of carbon dioxide absorption reaction kinetics into glycine
promoted methyldiethanolamine (MDEA) using laboratory scale wetted column equipment at
atmospheric pressure with varying temperatures from 303.15 to 328,15 the following results
is obtained :
1. The temperature and promoter concentration has an affection on absorption rate,
when we increase the temperature the absorption rate will increase, and also by
increasing promoter concentration from (1 -3% wt.) the reaction rate will be faster.
2. It is observed that the final concentration of carbonate will increase as result of
increment of temperature and concentration of promoter.
3. The overall reaction rate constant is affected by the temperature and promoter
concentration.
4. Correlation of reaction rate constant for reaction of CO2 with glycine and DEA using
MDEA is developed, the correlation of reaction rate constant (kglycine ) expressed
by the following equation :
= 5.3409E+13exp ( -3251.9 / T )
With activation energy for glycine promoter is 27.0363kJ/kmol.
While the apparent reaction rate constant was correlated as follows, kapp=A*exp (-ER/T)
where:
And correlation of reaction rate constant (DEA) expressed by ::
= 2.5715E+6exp ( -1665.8 / T )
5.When Diethanolamine(DEA) is used as promoter instead of glycine the carbon dioxide
Absorption rate also increase when the concentration of the promoter increase however
decrease when the temperature increase.
6.The value of glycine rate constant is larger than DEA rate constant at the same temperature
.
References
Ahmady. A,M.A. Hashim., (2012). Kinetics of Carbon Dioxide absorption into aqueous
MDEA + [bmim][BF4] solutions from 303-333k. Chemical Engineering Journal
200–202 , 317–328 .
Ahuja, D. A., (1990). Realative contributions of greenhouse gas emissition to global
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The Author Biograph
Yosry Elhosane Ahmed was born in AL Mikherif village -
South Gezira –Sudan in 1985 on 3 January. His father has two
wives. He is the fifth child out of ten children from his father
and the fifth child of six children from his mother.He studied
his primary and high school at Al-kumor Al-Ga’aleen school in
2003. He has studied his bachelor degree in chemical
engineering at AL-Imam AL-Mahdi University (kosti -Sudan)
in 2009. After two years, he works at his University as teaching
a assistance.
In 2013, he continued has study at Institute Teknology Sepuluh Nopember (ITS) ,
Faculty of Industry Technology, Chemical Engineering department, Surabaya, Indonesia .
The writer's interest is in chemical Engineering science specifically, Mass and Heat transfer.
For any acquiring do not hesitate to contact the Author via [email protected].
