Theoretical investigation of CO2 adsorption mechanism over amine-functionalized mesoporous silica

This study aimed to investigate CO2 adsorption over 3-(trimethoxysilyl)propylamine (APTMS) and trimethoxy[3(methylamino)propyl]silane (MAPS)-functionalized mesoporous silica by making use of DFT modeling with the purpose of elucidating the capture mechanism over amine-based sorbents, which is indeed very crucial for the rational design of prospective adsorbents that would meet the future challenges associated with CO2 emissions. Our calculations demonstrated that carbamate and carbamic acid were the two main adsorption products. Hydrogen bonding interactions with the surface silanols as well as the neighboring amines were critical for the formation and stabilization of the products. Besides, surface silanols not only played a significant role on the thermodynamics and kinetics of the reaction mechanism, but also could directly participate in the reaction. Amine functionality seemed to be less conclusive on the reaction mechanism compared to the surface silanols under the conditions employed in this study.

Automated summary

This study investigated CO2 adsorption over functionalized mesoporous silica and found that hydrogen bonding interactions with surface silanols and neighboring amines were critical for the formation and stabilization of the adsorption products. It was also shown that surface silanols played a significant role in the thermodynamics and kinetics of the reaction mechanism, and could directly participate in the reaction. The impact of amine functionality on the reaction mechanism was found to be less conclusive compared to surface silanols under the conditions employed in this study.