Investigation on Nanocomposite Membranes for High Pressure CO2/CH4 Separation

Abstract

The novel nanocomposite membranes were prepared for CO2/CH4 separation, and a good selectivity >30 at high pressure >30bar was obtained by testing a plate-and-frame module with a membrane area 110 cm2. The Joule- Thomson effect was found to have negligible influence on the temperature drop inside the membrane module due to the very high heat transfer coefficient for the membrane materials, which is different from the HYSYS simulation results. The water permeance was determined to be higher compared to CO2 permenace especially at high pressure, which indicated high water vapor content should be achieved in the feed gas to avoid the drying of the membrane and maintain high membrane separation performance in a real process. A two-stage membrane system was designed to purify CH4 from a 50% CO2/50% CH4 gas mixture, and the CH4 purity of 70% can be achieved in the 2nd stage. Process simulation using HYSYS integrated with ChemBrane indicated that a multi-stage membrane system is needed to achieve the industrial requirement on the production of sweet natural gas.