Biomethane

purified from biogas

can be utilized as substitute for natural gas owing to its high calorific value (HCV). Typically biogas contains 60%—65% CH4

35%—40% CO2

small amounts of hydrogen sulfide

water vapor and trace amounts of other gases. Treatment of raw biogas must be implemented in order to convert biogas into HCV biomethane. Membrane separation process exhibits many distinct advantages

including low energy consumption

high efficiency

high process flexibility and environment friendliness. Particularly

facilitated transport membrane exhibits predominant features for biogas upgrading because of its unique transport mechanism. Materials for facilitated transport membrane and corresponding preparation methods/technologies are summarized. Influences of impurities

such as water and hydrogen sulfide on membrane separation as well as some techno- economic issues are discussed. Finally

prospects on membrane separation technology in biogas upgrading are presented.