Direct Air Capture of CO₂ Using Amine/Alumina Sorbents at Cold Temperature

Rising CO2 emissions are responsible for increasing global temperatures causing climate change. Significant efforts underway to develop amine-based sorbents directly capture from air (called direct (DAC)) combat the effects of However, sorbents’ performances have usually been evaluated at ambient (25 °C) or higher, most often under dry conditions. A significant portion natural environment where DAC plants can be deployed experiences below 25 °C, and always contains some humidity. In this study, we assess adsorption behavior amine (poly(ethyleneimine) (PEI) tetraethylenepentamine (TEPA)) impregnated into porous alumina cold (−20 humid capacities °C 400 ppm highest 40 wt% TEPA-incorporated γ-Al2O3 samples (1.8 mmol CO2/g sorbent), while wt % PEI-impregnated exhibit moderate uptakes (0.9 g–1). both PEI- decrease with decreasing content temperatures. The 20 TEPA show best performance −20 conditions (1.6 1.1 g–1, respectively). Both also stable high working 1.2 g–1) across 10 cycles adsorption–desorption (adsorption desorption conducted 60 °C). Introducing moisture (70% RH improves capacity amine-impregnated PEI, TEPA, good results presented here indicate that PEI potential materials conditions, further opportunities optimize these scalable deployment different environmental