Molecular interactions between amine and carbonate species in aqueous solution — kinetics and thermodynamics

Abstract

Post combustion capture, PCC, of CO2 from the flue gas stream of coal fired power stations is an attractive proposition for the reduction of CO2 output into the atmosphere. PCC based on reversible absorption by aqueous amine solution is probably the most advanced technology. Thus the investigation of the chemistry of CO2 absorption by such solutions is of crucial importance. A critical reaction is the formation of carbamates. There is a vast literature on this process but it is mainly based on empirical reaction mechanisms. In this contribution we present a molecularly correct mechanism for carbamate formation with primary amines. The results are derived from detailed, 1H-NMR based, kinetic and equilibrium investigation of the interaction of monoethanolamine, MEA, with carbonate species. All rate and equilibrium constants are reported.