Methane Steam Reforming in Hydrogen-permeable Membrane Reactor for Pure Hydrogen Production

Steam reforming of methane over a ruthenium catalyst has been carried out at 500 degrees C in a membrane reactor equipped with a palladium membrane supported on a porous stainless steel tube. Hydrogen and carbon dioxide are mainly produced in the reaction, while hydrogen is selectively permeated through the membrane. Since equilibrium-shift takes place by hydrogen separation from the reaction mixture, the methane conversion significantly exceeds the equilibrium value, which is low at 500 degrees C. The selectivity to carbon monoxide by-produced in the reaction is lower than that expected from the equilibrium. Although the equilibrium conversion decreases with an increase in the reaction pressure, the conversion with the membrane reactor can increase because the hydrogen separation is promoted by the pressure increase. The catalytic activity is an important factor to produce a sufficiently high methane conversion and it is enhanced at a high reaction pressure.