Evaluation of porous adsorbents for CO2 capture under humid conditions: The importance of recyclability

Abstract

Breakthrough measurement has been the most common method for studying multicomponent adsorption of porous materials with a feed gas containing CO2, N2 and H2O. However, most studies of breakthrough measurement on novel adsorbents have focused on the CO2 adsorption that occurs during the first breakthrough run, thus leading to the misleading conclusion that the synthesized porous adsorbents are capable of capturing very large volumes of CO2 even in the presence of water vapor. Therefore, we conducted evaluations of CO2 adsorption on porous adsorbents by breakthrough measurement under dynamic conditions, using a range of commonly reported porous adsorbents and focusing on recyclability and kinetics. Aside from during a first run with fresh samples, most adsorbents showed poor recyclability in humid conditions. However, HKUST-1 and 1°-MCM-41 could capture CO2 under humid conditions over successive adsorption–desorption cycles. We also found that the sorption kinetics could be important for optimal utilization of amine-appended sorbents in industrial carbon-capture processes.

Keywords

• CO2 capture
• Porous adsorbents
• Water vapor
• Breakthrough measurement
• Recyclability
• Sorption kinetics