Biochar-mediated release of CO2 from monoethanolamine/H2O solution with low energy requirement over ZrO2/SiO2/biochar ternary catalysts.

CO 2 absorption technology based on amine solutions has sustained appeal due to its high efficiency in post-combustion capture of CO 2. However, the high energy penalty of solvent regeneration limits its large-scale industrial application. Therefore, designing inexpensive catalysts to reduce solvent regeneration energy consumption remains challenging. This study reports a recyclable ternary catalyst, ZrO 2 /SiO 2 /biochar, which was synthesized by co-pyrolysis of zirconium oxychloride and wheat flour in the presence of SiO 2 nanoparticles. The incorporation of biochar improved the distribution of Lewis acidic sites (LAS) and Brønsted acidic sites (BAS). The improved BASs and LASs of ZrO 2 /SiO 2 /biochar catalyst were conductive to donate protons or accept electrons and thus, the amount and rate of CO 2 desorption from CO 2 -saturated monoethanolamine (90 °C) were more than 24% and 26% higher, respectively, to compare with the catalyst-free system at the same conditions. As a result, the energy penalty was decreased by about 31%. A biochar-mediated proton-transfer mechanism that the presence of biochar increased the mesoporous proportion, the BAS and L/B ratio as well as the favorable charge transfer was inferred for the ZrO 2 /SiO 2 /biochar-catalyzed CO 2 release through experimental evidence. The results reveal the role of biochar in solid acid catalysts for CO 2 desorption, which will provide a novel strategy for building solid acid catalysts to reduce energy requirements in CO 2 capture. [Display omitted] • ZrO 2 /SiO 2 /BC was synthesized by co-pyrolysis of ZrOCl 2 and wheat flour in the presence of SiO 2 nanoparticles. • ZrO 2 /SiO 2 /BC catalysis accelerated CO 2 desorption and saved energy. • Biochar increased Brønsted and Lewis acidity of the catalyst. • Biochar promoted charge transfer between ZrO 2 and SiO 2. [ABSTRACT FROM AUTHOR]