(395aw) Surface Functionalization of Micro and Mesoporous Sorbents For Post-Combustion CO2 Capture

He, J., Stanford University
To, J., Stanford University
Lyons, C. T., Stanford University
Haghpanah, R., Stanford University
Gary, B., Stanford University
Rupp, E. C., National Energy Technology Laboratory
Bao, Z., Stanford University
Stack, D., Stanford University
Wilcox, J., Stanford University

Solid sorbent technologies for CO2 capture have several advantages over the traditional amine-based solvent absorption approaches. For instance, within an adsorption-based approach water is absent, which decreases the energy requirements associated with regeneration since heating a large amount of water is the greatest energetic expense associated with CO2 capture using solvent-based approaches.  Another benefit of using solid sorbents is the ability to tune the structural parameters of the material, as well as perform chemical modifications to enhance CO2 uptake.  In addition, materials such as carbon possess favorable heat conduction properties. 

Mesoporous silica materials have been highly developed in materials chemistry, and allow for more extensive chemical modification for CO2 capture.  While developing chemistry amenable to both silica and carbon surfaces, mesoporous carbon-based framework development will allow for heat to be dissipated readily during the adsorption process, which will lead to maximum capacity, in addition to the ease of heat transfer into the system for regeneration.

We aim to use careful chemical modification of mesoporous silica- and carbon-based materials to achieve highly selective, recyclable, and efficient materials for CO2 adsorption. Through careful tuning of the surface CO2 adsorption chemistry, we can control the thermodynamics and kinetics of carbon dioxide adsorption to allow for efficient material development. Our inspiration for this idea comes from carbonic anhydrase (CA), an enzyme that can selectively adsorb and regenerate CO2. CAs are found in the red blood cells of mammals, and are used to capture CO2 as bicarbonate, which can easily dissolve in blood and transported to the lungs.  The enzyme active site has been tuned such that the overall transformation is both kinetically fast and near thermodynamically neutral, allowing for both rapid and reversible CO2 conversion.  It is our aim to apply this design principle to sorbent-based technologies to enhance the mass transfer of CO2 from the gas to adsorbed phase, in addition to enhancing the kinetics associated with adsorption and desorption (regeneration) processes.