A review on polymeric membranes for natural gas purification

Raw natural gas consists of different hydrocarbon components. However there are other non-hydrocarbon components such as CO2, H2S, H2O, N2 and He. Among which, CO2 and H2S are considered as acid gases. CO2 causes the reduction of the heating value of the natural gas and may facilitate the formation of CO2 hydrates. The presence of H2S leads to corrosion of the pipeline and gas facilities. In addition, H2S enhances the toxicity of natural gas. Accordingly, acid gas removal is one of the most important steps in gas conditioning in order to meet the pipeline specifications as well as to pass the regulation limits. Although amine absorption is the well-known and mature technology, membrane technology is a new emerging process can be used for the purification of natural gas. The present review investigates the application of the polymeric membrane for the removal of acid gases (i.e., CO2 and H2S) from natural gas. Polymeric membranes used for acid gas removal, are mainly categorized to CA, Polyimides, Perfluoro-polymers, Poly sulfones, poly carbonates, Polyurethane, Pvm, Pvam, PBAX and PDMS. The combination of membrane and amine absorption technologies arises a new gas separation in this field called hybrid system which takes the advantages of both technologies. In this research work, different issues were discussed including: I) the parameters affecting the removal capacity of membranes; II) the approaches improving the membrane performance; III) membrane process design, configuration, optimization and economic analysis of hybrid system vs membrane only.