Study on the Roles of Water in Solid Amine-Based Direct Air Capture of CO2

Climate change triggered by the increasing amount of CO 2 released into the atmosphere has become a global priority. Direct Air Capture (DAC) of CO 2 has been regarded as one of the disruptive technologies to realize negative emission. Among the multiple strategies employed, adsorption on solid amines is a promising choice owing to its low energy requirements. Since the water vapor ubiquitously exists in ambient air, understanding the role it plays in DAC by the amine-functionalized solid sorbents is of vital importance. Due to the diversity in amine and support features, both promotion and deterioration of water impact on CO 2 adsorption were revealed. Herein we present a multifaceted review of the trends and innovations in DAC by solid amines under humid conditions. The effect of water was discussed over four groups of materials, based on the support categories, i.e ., (a) mesoporous silica, (b) mesoporous alumina, (c) mesoporous carbon and other inorganic supports, and (d) cellulose and other organic supports.