Chemical Engineering April 2022 - 5

Chementator
Mixed-salt processes target lower-cost
CO2 capture
A
mixed-salt process
(MSP) designed to
reduce the costs and
increase the energy
efficiency of removing carbon
dioxide from post-combustion
fluegas is advancing in two
related projects. In the first,
a 10-MW engineering-scale
demonstration plant for the
MSP is under construction at
the University
of
NETL
CO2 emmitter facility
Edited by:
Gerald Ondrey
Regeneration
tower
CO2 absorption
towers
ENZYMES IN A CAGE
Researchers at the Karlsruhe
Institute of Technology
(KIT; Germany;
www.kit.edu) have embedded
enzymes
into
Illinois'
(Urbana-Champaign;
www.illinois.edu) Abbott Power
Plant. In the second, researchers are conducting
bench-scale development and
testing of a new solvent formulation for the
MSP that is designed to further improve the
process economics.
MSP emerged from earlier work by SRI
International (Menlo Park, Calif.; www.sri.
com) that investigated chilled ammonia as a
solvent for CO2 capture (Chem. Eng., July
2013, p. 11).
The MSP, which was licensed to Baker
Hughes (Houston; www.bakerhughes.com)
in 2021, uses a non-degradable solvent
based on inexpensive K2CO3 and NH3 solutions
to remove CO2 from power plant
exhaust gas. The National Energy Technology
Laboratory (NETL; Morgantown, W.Va.;
www.netl.doe.gov), which is providing costshared
funding for the two projects, notes
that in the MSP chemistry, NH3 plays a dual
role as a catalyst and as an absorbent, due
to its high mobility and reactivity with CO2.
" By operating absorbers near ambient temperature,
solvent-chilling energy requirements
are reduced, as is water usage and ammonia
loss, resulting in reduced operational costs, "
according to NETL technology manager Andrew
Jones. Also, high-pressure stripping
and
heat recovery
within
the
regenerator
Flue-stream
collection
conduit
Particulate bag-house
& sulfur scrubber
reduces CO2 compression requirements,
which lowers both capital and
operational costs, project leaders state.
The MSP demonstration plant, slated to
be completed in 2024, aims to test the process
with real-world fluegas for long time
periods, while demonstrating the process
efficiencies and gathering information for a
techno-economic analysis.
Meanwhile, SRI is conducting large
bench-scale testing on an advanced version
of the MSP (A-MSP). In this project, the tertiary
amine methyl diethanolamine (MDEA),
traditionally used for treating acid gas, is
added to the solvent formulation to increase
the CO2 loading and reduce parasitic energy
loss. " The key advantage of the A-MSP design
is operation of the regenerator at low
temperature and high pressure,
eliminating
water stripping and thus generating a
greater than 99%-pure dry CO2 stream, "
says Jones. This results in cost reductions
for solvent regeneration and CO2 compression
and allows the removal of the expensive
first CO2 compression stage.
Recycling polyesters, polycarbonates and more
- at room temperature
A
new catalytic recycling method that avoids harsh
processing conditions could widely expand the
recyclability of a broad range of plastics, including
polycarbonates, polyesters and mixed-waste
feeds. Researchers from the Center for Sustainable and
Circular Technologies (CSCT; www.ccst.ac.uk) at the University
of Bath (www.bath.ac.uk) reported that the process,
which employs a zinc-based catalyst and methanol,
could fully break down poly-bisphenol A carbonate (BPAPC)
beads into bisphenol A (BPA) and dimethyl carbonate
(DMC) in just 20 min at room temperature. By efficiently
breaking down BPA-PC, the catalyst not only handles a
difficult-to-recycle waste stream, but it also prevents BPA,
a harmful pollutant, from leaching into the environment.
This is said to be the first instance of metal-mediated
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
BPC-PC methanolysis showing high activity at room
temperature. In addition to methanolysis, the team investigated
several chemical strategies, such as alcoholysis,
glycolysis and aminolysis, to maximize the range of attainable
products from different waste streams using the
new catalyst. The catalyst can also break down other
plastic materials, including polylactic acid (PLA), polyester
amides (PEAs) and polyethylene terephthalate (PET).
Traditional recycling technologies for these materials include
energy-intensive processes like pyrolysis or hydrosilylation,
so the ability to rapidly recycle them into their
chemical constituents at ambient conditions brings many
economic and sustainability benefits. The team has demonstrated
the technology at laboratory scale, and work is
ongoing to scale up the reaction volume.
APRIL 2022
5
metal-organic frameworks
(MOFs), and demonstrated
for the first time
that stabilization by these
frameworks is sufficient
for use of the enzymes in
a continuous reactor. The
enzymes are stabilized in
both aqueous and organic
solvents.
Using an enzyme-MOF
flow reactor, the researchers
found that the stability
of the immobilized enzyme
was about 30 times
that of the free enzyme,
while the catalytic activity
reached about 30%
of that of a free enzyme.
The study was reported
in a recent issue of Angewandte
Chemie.
NEW IX RESIN
Lanxess AG (Cologne,
Germany; www.lewatit.
com has added Lewatit
TP 308 to its range of
selective ion-exchange
(IX) resins, which are suitable
for the purification of
lithium salt solutions. The
macroporous Lewatit TP
308 has been developed
specifically to treat lowconcentration
lithium salt
solutions (<2 g/L) con(Continues
on p. 6)
To sequestration
http://www.kit.edu http://www.illinois.edu http://www.sri.com http://www.bakerhughes.com http://www.lewatit.com http://www.netl.doe.gov https://www.csct.ac.uk/about-us/ http://www.bath.ac.uk http://WWW.CHEMENGONLINE.COM
Chemical Engineering April 2022

Table of Contents for the Digital Edition of Chemical Engineering April 2022
