An emerging technology is the membrane reactor for steam reforming. In this system, the steam reforming, water gas shift and hydrogen purification steps all take place in a single reactor. The methane and steam mixture are fed into a catalyst-filled reactor. On one side of the reactor is a palladium membrane that is selectively permeable to hydrogen. As the steam reforming reaction proceeds, the hydrogen is driven across the membrane by the pressure difference. Depending on the temperature and pressure, the methane can be completely converted and pure hydrogen can be produced.