Absorption of Carbon Dioxide by a
Suspension of Activated Carbon in
Aqueous Amine Solutions
Yahia Alhamed
King Abdulaziz University
Faculty of engineering
Department of Chemical and Materials Engineering,
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
1
Introduction
Main features of CO2
• As a feed
– Chemical industries (e.g. urea production)
– Food and beverage carbonation.
• As an impurity
– Natural gas processing
– Ammonia synthesis
• As a pollutant
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
2
CO2 Removal Using Amines
MEA and DEA are widely used in industry.
TEA is less used due to its lower capacity,
higher cost, and lower reactivity.
The capacity of 1ry amines is limited to  0.5
mole CO2/mole amine.
Any increase in the absorption capacities of
these systems for CO2 will definitely improve
the economics of these processes.
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
3
Previous Studies (Achievements)
• Significant enhancement of CO2 absorption rate into
water-activated carbon (AC) slurries.
• The feasibility of using immobilized 1ry amine in
place of homogeneous additives to enhance CO2 in
3ry amine solutions.
• Use activated carbon (AC) as a solid activator.
– Higher rate of absorption of CO2.
– Unknown absorption capacity in the presence of
AC.
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
4
Objectives
• Study the effect of AC (activator) on the
absorption capacities of CO2 in a suspension of
AC - aq. amine solution.
• Study the effect of amine type, amine
concentration and AC loading on the adsorption
capacities.
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
5
Experimental
Dryer
To soap film meter
CO2 Mass flow controller
To GC for analysis
F
V1
Bubble column
F
N2 Mass flow controller V2
Dryer
CO2 Cylinder
To soap film meter
V3 -
To GC for analysis
N2 Cylinder
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
6
Breakthrough curves of CO2
flow rate of CO2 leaving the
absorption column (ml(STP)/min.)
250 ml of 0.05 mol/l MEA, CO2 = 0.2, at 250 ml (STP)/min,
50
40
Cc
Cc
Cc
Cc
Cc
Cc
30
20
10
= 0 g/l
=5 g/l
= 10 g/l
=30 g/l
=50 g/l
=100 g/l
0
0
10
20
30
40
Time (min.)
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
7
Effect of AC loading on CO2 absorption capacity
R is defined as:
CO2 absorbed by amine(aq)  AC
CO2 absorbed by amine(aq)
R > 1  increase absorption capacity due to AC
addition.
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
8
Effect of AC loading on R for DEA solution
YCO2 = 0.4; total feed rate = 150 ml (STP)/min.
4.5
CA = 0.0 mol/l
CA = 0.05 mol/l
CA = 0.1 mol/l
CA = 0.3 mol/l
R
3.5
2.5
1.5
0.5
0
10
20
30
40
AC loading (g/l)
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
9
R versus AC loading for MEA concentration
4.5
R
3.5
2.5
CA = 0.05 mol/l
1.5
0.5
0
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
20
40
60
80
AC loading (g/l)
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
100
120
10
R vs AC loading at various concentrations of TEA.
1.4
1.3
1.2
1.1
R
1.0
0.9
CA = 0.01 mol/l
CA = 0.05 mol/l
CA = 0.1 mol/l
CA = 0.2 mol/l
0.8
0.7
0.6
0.5
0
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
20
40
AC loading (g/l)
60
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
80
100
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Conclusions
• Adding AC to amine solutions is beneficial.
• Addition of AC (activator) allows the use of
lower amine concentrations while keeping the
same absorption capacity.
• This is more beneficial in case of MEA
(corrosive than DEA) at concentrations > 20%
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
12
Further work
Effect of :• AC particle size,
• Temperature,
• flow rate and composition of the gas,
Adsorption studies of amines by AC are very
important to explain the results obtained.
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
13
• Thank you very much for your attension
Dr. Y. Alhamed KAU
Jeddah Saudi Arabia
CHEMINDIX2007 Manama
Bahrain 26 - 29 April 2007
14