Selective oxidation of carbon monoxide in hydrogen-rich mixtures by permeation through a platinum-loaded Y-type zeolite membrane

A defect-free Y-type zeolite membrane was synthesized on the inner surface of a porous α-alumina support tube (i.d.=1.7 mm, o.d.=2.1 mm) by a hydrothermal process. The membrane was ion-exchanged with an aqueous 2.5 mmol l−1 solution of [Pt(NH3)4]Cl2 to give a Pt-loaded Y-type zeolite membrane (PtY membrane), was obtained by calcination in air and by reduction in a flow of H2. The PtY membrane was then applied to a membrane reactor system for selective oxidation of carbon monoxide, which was included in H2 at a concentration of 104 ppm. The total pressure on the feed and permeate sides was maintained at atmospheric pressure, and the permeate side was swept with an inert gas. The H2 flux through the PtY membrane was independent on the O2 concentration in the feed. When the feed rate of O2 was 1.2 times that of CO, the CO concentration on the permeate side was decreased to less than 8 ppm at temperatures of 200–250°C. When steam was added to the feed at a concentration of 2%, the H2 and CO fluxes through the membrane remained fundamentally unchanged.