Synthesis of Pt-zeolite coated palladium alloys as catalytic membranes for hydrogen production

PdAu composite membranes were applied for the preparation of PtNaA-PdAu catalytic membranes for hydrogen production from the water gas shift reaction. In the first stage, the deposition of NaA zeolite on top of the PdAu alloys was optimized. Functionalization employing a 1.0 v/v % 3-aminopropyltriethoxysilane solution prior to both seeding and hydrothermal synthesis allowed obtaining a homogeneous and complete PdAu alloy surface coverage. Even though the NaA zeolite coverage decreased the pure hydrogen permeance at 623 K and 50 kPa in comparison with a PdAu membrane, the resistance to a CO containing stream was higher. From direct incorporation of Pt during the zeolite synthesis, a homogeneous, well-intergrown PtNaA zeolite coverage on top of a PdAu alloy membrane was obtained. PtNaA catalytic tubular membranes were evaluated in the water gas shift reaction at 673 K. The membranes were active and stable under reaction conditions, without evidence of methane formation.