(173h) Modified Amine-Based Sorbent in Monolithic Structure 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. Its performance was compared with that of unmodified amine-based sorbent on the same monolithic structure. Modified amine-based sorbent washcoated on a monolithic structure showed slightly lower adsorption capacities than unmodified sorbent on the same structure due to lower binding energy between adsorbed CO₂ molecules and modified amine sites. However, modified amine-based sorbent on the monolith showed higher CO₂ recovery than unmodified amine-based sorbent on the same monolithic structure under the same temperature vacuum swing adsorption conditions. The amount and purity of gases recovered from the monolith were analyzed using CO₂ analyzer and mass spectrometer.

Based on the performances of the small monolith blocks, the performances of large monolith blocks with unmodified and modified amine-based sorbents were also evaluated in a DAC system placed in an environmental chamber under various temperature, humidity and wind speed conditions simulating different climatic conditions. In this presentation, the performances of modified amine-based sorbent on monolithic structure will be 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.