(700e) Epoxide-Modified Aminopolymer-Based CO2 Adsorbent for Direct Air Capture

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

In this study, epoxide-modified polyethylenimine (PEI)-based sorbent has been studied for DAC potential. The sorbent performances were examined using 1, 2-epoxybutane (EB)-modified PEI-impregnated mesocellular silica foam (MCF). The sorbent showed consistent saturated adsorption capacities of ~1.6-2 mmol CO₂/g of sorbent from 400 ppm CO₂in air between 25-40 °C. The sorbent could also be regenerated in 100% CO₂at 110-120 ºC and showed consistent and reliable adsorption and desorption performances during the adsorption and desorption over 100 cycles. It showed robust performances with minimum oxidative and thermal degradation over long-term adsorption and desorption cycles. It could readily achieve >95% CO₂ purity and also greatly reduce the current CO₂ desorption thermal energy requirement for PEI-based sorbent by up to ~45%.