(298f) Effect of the Support Characteristic on Direct Air Capture Performance for PEI-Incorporated Sorbents

Polyethylenimine-based sorbents have been widely used for direct air capture of CO2, and the CO2 sorption performance depends sensitively on the porous substrates, while the mechanisms are yet to be determined. Herein, we prepare two series of sorbents based on poly(1-trimethylsilyl-1-propyne) (PTMSP) with high surface area but moderate porosity and biodegradable cellulose-aerogel blends (CAB) with high surface area and porosity. Specifically, PTMSP and PEI were dissolved in tetrahydrofuran, which was then cast to obtain thin films (15-20 µm); CAB films was immersed in PEI/methanol solution, which was then dried to obtain the sorbents. The structure and morphology of the sorbents were thoroughly characterized as a function of the PEI loading (0 – 50 mass%). For example, adding 30 mass% PEI in PTMSP increases CO2 sorption to 0.39 mmol/g while decreasing surface area from 800 to 100 m2/g; introducing 30% PEI in CAB increases CO2 sorption from 0 to 0.25 mmol/g while decreasing surface area from 500 to 124 m2/g. Both materials showed good cyclic stability for over 10 adsorption/ desorption cycles. These findings will help in highlighting the effect of tailoring substrate properties and synthesis methods on the DAC performance of the materials. This work will provide insights into the development of next-generation DAC materials, which are environmentally sustainable and durable.