Application of polyimide membranes for biogas purification and enrichment

In the paper the results of the tests of the CH4 enrichment in simulated biogas mixture consisted of methane, carbon dioxide and hydrogen sulphide were presented. It was showed that using the capillary module with polyimide membranes it was possible to achieve the enrichment of CH4 from the concentrations of 55-85% up to 91-94.4%. The membrane material was resistant to the small concentrations of sour gases and assured the reduction of H2S and water vapour concentrations, as well. The required enrichment was achieved in the single module, however to prevent CH4 losses the multistage or hybrid systems should be used to improve process efficiency.