Performance of alumina, zeolite, palladium, Pd–Ag alloy membranes for hydrogen separation from Towngas mixture

The hydrogen permeation and separation properties of alumina, zeolite (ZSM-5), palladium and Pd–Ag alloy membranes were measured and compared. Hydrogen separation from a commercial Towngas mixture (49% H2, 28.5% CH4, 19.5% CO2 and 3% CO) was conducted. The commercial alumina membrane displayed excellent hydrogen permeation rate but was unable to separate hydrogen from the Towngas. Supported ZSM-5 membrane prepared by ex situ method was able to produce a product stream containing 60% H2 from Towngas, whereas, high purity hydrogen was generated using thin palladium and Pd–Ag alloy membranes prepared by electroless plating technique. Some of the constituent gases in Towngas mixture inhibit hydrogen flux through the palladium membrane, but the addition of silver serves to ameliorate the situation.