Hydrogen concentration and purification by membrane process: a multistage analysis

In this work, the concentration and purification of hydrogen from multicomponent gas mixtures, such as syngas and H2:CH4 blends, were investigated by simulations of multi-stage membrane configurations. In particular, the separation performance of carbon, polymeric and Pd-alloy membranes were analyzed for obtaining a final H2 stream completely pure with a recovery higher than 90%. Carbon and polymer membranes in multistage configuration confirmed their suitability to be used as concentration units able to increase the hydrogen content in the gas mixture. A further purification of these pre-concentrated streams was carried out adding Pd-alloy membranes that were able to recover more than 90% of hydrogen fully pure. The use of an integrated process constituted of a concentration stage based on polymer/carbon membranes followed by a purification stage based on a Pd-alloy membrane allowed to drastically reduce the operating pressure and, moreover, save Pd-alloy membrane area.