Membrane Reactor

A membrane reactor is a device that combines a chemical conversion process with a membrane separation process in a single unit, adding reactants or removing products as the reaction proceeds. In hydrogen production from natural gas, a membrane reactor can fold the separate steps of conventional processing, steam reforming, the water-gas shift reaction and purification, into one unit, offering economic and environmental advantages over running them apart. Palladium and palladium-silver alloy membranes are favored for industrial hydrogen separation because palladium dissolves hydrogen exceptionally well despite its high cost; hydrogen passing through such a membrane adsorbs onto its surface, dissociates into atoms, diffuses across, recombines and desorbs on the low-pressure side. By continuously removing hydrogen as it forms, a membrane reactor can push a reaction past the conversion limit set by thermodynamic equilibrium, or reach the same conversion at a lower temperature, which is especially useful for equilibrium-limited reactions that absorb heat.