Hybrid Membrane Absorption Process for Post Combustion CO2 Capture

Gas Technology Institute (GTI) and PoroGen Corporation are jointly developing a novel hybrid membrane – absorption process for pre- and post-combustion CO2 capture (Carbo-Lock™ process). The novel Carbo-Lock™ process combines advantageous features of both absorption and membrane processes to generate cost-effective separation and capture of CO2 from various emission sources. Together the organizations are making extensive laboratory and bench-scale measurements to bring this technology development to commercialization. The Carbo-Lock™ process is a hybrid of membrane and the conventional absorption processes. CO2-containing gas passes through small membrane tubes (hollow fibers with porous walls) while a CO2 selective solvent (typically an amine solution) flows on the shell side of the membrane tubes. CO2 passes through the nano-porous membrane and is absorbed in the selective solvent. The CO2 rich solvent can be regenerated in a second membrane module operated in a reverse process. The Carbo-Lock™ process uses a novel hollow fiber membrane technology patented by PoroGen. This novel membrane is made from a chemically and thermally stable commercial engineered polymer poly(ether ether ketone) or PEEK. The PEEK membrane contactor can provide a platform for solvent-based systems beyond conventional amines. The reduced size requirements translate to lower solvent inventories, less metal exposure to corrosive liquids, and lower visual impact (smaller footprint) for siting at congested power plants. Since the gas and liquid phases are not directly in contact, the solvent purity levels are expected to remain high and solvent losses, from foaming and carryover, are expected to remain low. Utilizing the membrane contactor in the regeneration section will greatly reduce energy usage for desorbing CO2 from the solvent. The system operates at very low gas pressure drops, comparable to those achieved with very large diameter columns, and much lower than those of conventional membrane systems. The preliminary test and computer simulation results of hybrid Carbo-Lock™ membrane-absorption process are presented in this paper.