(668f) Sorbent-Coated Monolithic System for Direct Air Capture

A large portion of CO₂ emissions in ~5.2 gigatons (Gt) is released in relatively small quantities from distributed sources emitted each year in the U.S. Therefore, for such emissions, point source CO₂ capture is not feasible and direct air capture (DAC) is an indispensable part of a diversified portfolio of technologies to mitigate U.S. greenhouse gas emissions. Successful DAC technologies require the separation of high purity CO₂ (e.g., >95%) with high selectivity toward CO₂, low energy requirements, minimum chemical and thermal degradations, reliability, long lifetime, etc.

Adsorption-based CO₂ separation for DAC requires low pressure drop and low desorption energy. In this study, modified amine-based sorbent in a powdered form was washcoated onto a monolithic structure. The 100 cyclic performances of modified amine-based sorbent on monolithic structure were compared with those of unmodified amine-based sorbent on the same structure. The performances of these two sorbents on the monolithic structure will be compared in terms of adsorption capacities, kinetics, desorption energy requirements, and stability.

Its performance was compared with that of unmodified amine-based sorbent on the same monolithic structure. Modified amine-based sorbent coated onto a monolith structure showed higher CO₂ recovery than unmodified amine-based sorbent onto the same structure under the same temperature vacuum swing adsorption conditions. The higher CO₂ recovery is attributed to the reduced bonding strengths and thus faster desorption kinetics of CO₂ molecules from the modified amine sites. The desorption profiles of water vapor and CO₂ gas during the desorption phase will also be presented. The amount and purity of gases recovered from the monolith were analyzed using CO₂ analyzer and mass spectrometer. Diffuse reflectance infrared Fourier transform spectroscopic (DRIFTS) analysis data for the monolith block coated with modified amine-based sorbent also shows reduced oxidative degradation over that with unmodified amine-based sorbent. A preliminary techno-economic analysis based on the performances data will also be presented.