(144f) Effect of Moisture on Sub-Ambient DAC with MIL-101(Cr)-Amine Sorbents

The level of humidity in air is a crucial factor that impacts the performance of solid sorbents in direct air capture (DAC) of CO₂, impacting sorption kinetics, thermodynamics and energy consumption in sorbent regeneration. There may be advantages to operating DAC technologies in regions where the absolute humidity is low. As the absolute humidity dramatically reduces with decreasing temperature, it may be advantageous to operate DAC plants in cold or temperate climates. Unfortunately, very few DAC sorbents have been studies under “sub-ambient” conditions (< 20 ºC). In this study, amine-impregnated (TEPA, tetraethylenepentamine or PEI, poly(ethyleneimine)) MIL-101(Cr) metal-organic frameworks (MOFs) are prepared, characterized, and used as model sorbents for sub-ambient DAC. Their 400 ppm CO₂ adsorption behavior is investigated at sub-ambient and humid conditions with CO₂/H₂O temperature programmed desorption (TPD) and in situ FTIR spectroscopy, supplemented by cyclic sorption/desorption cycling to probe the potential for low temperature DAC operation.