Removal of Acid Gases from Methane-Containing Gas Mixtures by Membrane-Assisted Gas Absorption. Hollow-Fibre Module Configuration with Absorption System Based on Dimethyldiethanolammonium Glycinate

The present study is focused on continuing the development, improvement and optimisation of a new hybrid separation method – membrane-assisted gas absorption, which is designed for processing methane-containing gas mixtures, namely for the removal of acid gases. The second part is devoted to the design of absorbent solutions and their application in the proposed technology in order to improve the efficiency of acid gas removal and reduce hydrocarbon losses. Absorbents of acid gases based on aqueous solutions of methyldiethanolamine containing ionic liquid [M2E2A][Gly] have been proposed and investigated. As a result of the study, the optimal absorbent composition for further separation tests in a membrane-assisted gas absorption unit was determined. The efficiency of the process was investigated on the example of 8-component gas mixture containing methane, ethane, propane, n-butane, nitrogen, carbon dioxide, hydrogen sulfide and xenon. The membrane-assisted gas absorption unit demonstrated high efficiency of acid gas removal and high hydrocarbon recovery. The final efficiency of the investigated system with the new absorbent was up to 99 % for acid gas removal with hydrocarbon losses of up to 1 % at maximum capacity.