Effects of membrane selectivity and configuration on methane purity and recovery from high carbon dioxide content natural gas

Abstract Many membranes for gas separation and purification reportedly exhibit carbon dioxide/methane selectivity of 2.6 to 37 for polymer membranes and as high as 42.65 for inorganic membranes. Researches on improving membrane selectivity appear to be on the rise because higher selectivity is thought to offer better carbon dioxide capture and removal. However, the present study demonstrates that a membrane, even with high carbon dioxide/methane selectivity of 750 with flow configuration of Type 1, could not enrich methane effectively from high carbon dioxide content natural gas to the purity level that meets the natural gas pipeline quality of 75%. Thus, the membrane is not suitable for application in some of Malaysian, Australian and Brazilian gas fields which contain extraordinarily high carbon dioxide. Results from the present study demonstrate that methane was successfully enriched to 81.41% in the permeate when membrane with methane/carbon dioxide selectivity of 1000 with flow configuration of Type 2 was used. This paper addresses the concern regarding the efficacy of high membrane selectivity in methane enrichment process from high carbon dioxide content natural gas and provides the necessary correlations, analyses, and suggestions.