A review of potential amine solvents for CO2 absorption process: Absorption capacity, cyclic capacity and pKa

Abstract

Solvent selection is an important element to enable low energy requirement in post combustion CO2 capture process by means of chemical absorption. In this paper, we investigated the CO2 capture performance of 132 different aqueous amine solvents available in the literature. The properties studied were absorption capacity, cyclic capacity and the pKa – absorption capacity relationship. In addition, fast solvent screening was critically evaluated.

Based on published data, no single amine showed superior performance in terms of absorption capacity and cyclic capacity. However, most of the studied amine solvents showed a better performance than MEA. In some cases, amines studied using the different screening techniques showed results which contradicted with the equilibrium value; the screening work seemed to lead to results where the equilibrium value was exceeded. Further, it was indicated that a solvent with promising cyclic capacity with desorption at 70 °C or 80 °C, not necessarily show the same potential with desorption at 120 °C. Thus, the value of the screening experiments can be questioned. At last, it was found a linear relationship between the pKa value of an amine solvent and its absorption capacity.