ABSTRACT
This chapter discusses the progresses in design and preparation of asymmetric membranes for natural gas purification, particularly focusing on the CO2/CH4 separation. The interfacial polymerization approach is adopted from the development of thin-film composite membranes for water purification, where interfacial polymerization reaction occurs at the solvent interface between one monomer dissolved in aqueous solution and another monomer dissolved in organic solution. One of the challenges for polymeric membranes is plasticization, especially in practical natural gas purification that usually involves aggressive feed conditions. The dual-phase membranes have absolute selectivity for CO2, while low permeability and they must be operated at very high temperature, which are unattractive for practical natural gas purification. Compared with purely inorganic zeolites, metal-organic frameworks with organic linkers offers a more compatible interface with organic polymers, showing great potential in remarkable performance improvement, as well as scalable fabrication of asymmetric membranes.
