Preparation of thin Pd membrane on CeO2-modified porous metal by a combined method of electroless plating and chemical vapor deposition

A thin Pd membrane with a thickness of 6 μm has been prepared on a commercially available macro porous stainless steel (MPSS) tube using an electroless plating technique followed by the surface modification with cerium hydroxide particles. The hydrogen flux through the membrane is as high as 0.235 mol/(m2 s) at 773 K with a pressure gradient of 100 kPa, but the separation factor (H2/Ar) is only 14 due to the surface defects. The other membrane with a Pd thickness of 10 μm prepared by the same method produces a high separation factor of 108, but the hydrogen flux decreases to 0.178 mol/(m2 s). The defects of the 6 μm membrane can be removed by the chemical vapor deposition (CVD) of a Pd complex on the surface. After the CVD treatment for three times, the separation factor increases greatly to 565 without decreasing the original hydrogen flux. Hence, the combined method of electroless plating and CVD provides a good route for preparing thin Pd/CeO2/MPSS composite membranes with high hydrogen permeability and selectivity.