Experimental and kinetic study of the catalytic desorption of CO
2
from
CO
2
-loaded monoethanolamine (MEA) and blended
monoethanolamine e Methyl-diethanolamine (MEA-MDEA) solutions
Ananda Akachuku, Priscilla Anima Osei, Benjamin Decardi-Nelson, Wayuta Srisang,
Fatima Pouryousefi, Hussameldin Ibrahim, Raphael Idem
*
Clean Energy Technologies Research Institute (CETRI), Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan, S4S 0A2,
Canada
article info
Article history:
Received 6 March 2019
Received in revised form
23 April 2019
Accepted 24 April 2019
Available online 7 May 2019
Keywords:
CO
2
desorption
Solid acid catalyst
Kinetics
Mechanistic model
Activation energy
Acid sites
abstract
The kinetics of catalyst-aided desorption of CO
2
from CO
2
-loaded MEA (5 mol/dm
3
) and blended MEA-
MDEA (7 mol/dm
3
) solutions at CO
2
loadings from 0.3 to 0.5 mol CO
2
/mol amine were studied over a
Lewis acid catalyst (g-Al
2
O
3
) and a Brønsted acid catalyst (H-ZSM-5) in an absorberedesorber CO
2
capture bench-scale plant (columns of 0.051 m ID and height of 1.067 m) at temperatures of 348e368 K.
The results showed that the conversion increases relative to no catalyst for MEA were 55 and 74% while
for MEA-MDEA, they were 65 and 85.2% with g-Al
2
O
3
and H-ZSM-5, respectively. A comprehensive
mechanistic LHHW rate model was developed for the catalytic CO
2
desorption process.
© 2019 Elsevier Ltd. All rights reserved.
1. Introduction
Carbon dioxide (CO
2
) is known to be a major contributor to
global warming due to its ever-increasing atmospheric concentra-
tion resulting mainly from human activities such as fossils fuel
combustion and deforestation. In the fight to reduce the industrial
emission of CO
2
, a landmark agreement aimed at keeping the global
temperature rise below 2
C above the pre-industrial levels was
reached at the 21st Conferences of Parties, COP 21, Paris summit [1].
This reduction in global temperature demands that more emphasis
is placed on the development and modification of new and existing
Carbon Capture Storage (CCS) technologies. Amine-based post-
combustion CO
2
capture (PCCC) has been reported to be one of the
most promising and efficient mitigation technologies used in CO
2
capture due to its capability of handling large amounts of exhaust
gas streams in a cost-effective manner [2,3]. It is a well known fact
that the regeneration of CO
2
from loaded amine occurs at an
elevated temperature within the range of 120e140
C[4]. This high
operational temperature introduces several drawbacks such as high
parasitic heat duty, solvent loss, and degradation, as well as stress
cracking corrosion, thus making amine PCCC a cost-prohibitive
process [5]. Meanwhile, about 70% of the operating cost is attrib-
uted to the energy requirement for amine regeneration [6], which
indirectly reduces the overall efficiency of the power plant to
approximately 30e40% if integrated with the CCS unit [7]. This
generates a large interest in the heat duty for regeneration, making
it one of the most important parameters that should be carefully
accounted for in the economic evaluation of the CCS technology [8].
The reaction kinetics is another essential parameter needed for
process design and optimization and highly depends on solvent
chemistry. Consequently, a robust and comprehensive model is
needed to account for the fundamental mechanism of the kinetic
phenomena underlying CO
2
absorption and desorption reactions.
Also, there is a need for a faster reaction rate because it allows for a
smaller absorber/desorber unit as well as reduced heat transfer
units.
Monoethanolamine (MEA), diethanolamine (DEA) and methyl-
diethanolamine (MDEA) are some commonly used solvents in
amine-based PCCC [9]. The reaction kinetics and mechanism of * Corresponding author.
E-mail address: Raphael.idem@uregina.ca (R. Idem).
Contents lists available at ScienceDirect
Energy
journal homepage: www.elsevier.com/locate/energy
https://doi.org/10.1016/j.energy.2019.04.174
0360-5442/© 2019 Elsevier Ltd. All rights reserved.
Energy 179 (2019) 475e489