Direct Air Capture of CO₂ with an Amine Resin: A Molecular Modeling Study of the CO₂ Capturing Process

Several reactions,
known from other amine systems for CO2 capture, have been
proposed for Lewatit R VP OC 1065. The aim of
this molecular modeling study is to elucidate the CO2 capture
process: the physisorption process prior to the CO2-capture
and the reactions. Molecular modeling yields that the resin has a
structure with benzyl amine groups on alternating positions in close
vicinity of each other. Based on this structure, the preferred adsorption
mode of CO2 and H2O was established. Next, using
standard Density Functional Theory two catalytic reactions responsible
for the actual CO2 capture were identified: direct amine
and amine-H2O catalyzed formation of carbamic acid. The
latter is a new type of catalysis. Other reactions are unlikely. Quantitative
verification of the molecular modeling results with known experimental
CO2 adsorption isotherms, applying a dual site Langmuir
adsorption isotherm model, further supports all results of this molecular
modeling study.