One-Step Synthesized SO42-/ZrO2-HZSM-5 Solid Acid Catalyst for Carbamate Decomposition in CO2 Capture.

Amine-based CO2 capture technology requires high-energy consumption because the desorption temperature required for carbamate breakdown during absorbent regeneration is higher than 110 °C. In this study, we report a stable solid acid catalyst, namely, SO42-/ZrO2-HZSM-5 (SZ@H), which has improved Lewis acid sites (LASs) and Bronsted acid sites (BASs). The improved LASs and BASs enabled the CO2 desorption temperature to be decreased to less than 98 °C. The BASs and LASs of SZ@H preferred to donate or accept protons; thus, the amount and rate of CO2 desorption from spent monoethanolamine were more than 40 and 37% higher, respectively, when using SZ@H than when not using any catalyst. Consequently, the energy consumption was reduced by approximately 31%. A catalyzed proton-transfer mechanism is proposed for SZ@H-catalyzed CO2 regeneration through experimental characterization and theoretical calculations. The results reveal the role of proton transfer during CO2 desorption, which enables the feasibility of catalysts for CO2 capture in industrial applications.