Rapid CO₂ absorption into aqueous benzylamine (BZA) solutions and its formulations with monoethanolamine (MEA), and 2-amino-2-methyl-1-propanol (AMP) as components for post combustion capture processes

Our recent studies have identified benzylamine (BZA) as a promising candidate for CO₂ capture processes, however the formation of stable and insoluble BZA-carbamate salts in highly concentrated unblended BZA solutions, and at high CO₂ loadings, severely restricts the working concentration of the unblended BZA solvent. Thus, BZA is ideally placed as a candidate for use in a formulated solvent to improve the overall amine concentration and CO₂ loading which can be used.The current work focuses on the investigation of CO₂ absorption into aqueous solutions of BZA as well as formulations of BZA incorporating MEA and AMP as the second amine components, respectively. Mass transfer/kinetic measurements using a wetted wall column (WWC) at 40°C have been performed for a series of unblended BZA solutions as well as a series of amine concentrations and ratios in the formulations. Overall mass transfer coefficients as a function of total CO₂ loading in the solutions (0.0-0.4mol CO₂/total mole amine in solution) have been determined for the unblended BZA solutions and formulations. CO₂ absorption rates into unblended BZA solutions are significantly faster than in MEA solutions at similar concentrations and zero CO₂ loading. The majority of the BZA formulations investigated here can be considered promising candidates for CO₂ capture and possess larger or comparable mass transfer rates (up to 30% increase at low loadings) when compared to the corresponding unblended 5.0 and 6.0M MEA solutions under similar conditions. Formulations containing BZA and MEA demonstrated the fastest CO₂ absorption rates overall due to the presence of two fast reacting amines, both of which can actively and directly contribute to the absorption of CO₂