Hollow-Fiber-Supported Gold and Zirconium-Doped Faujasite Catalytic Membranes for Hydrogen Purification

Hollow-fiber-supported Au-Zr/faujasite (FAU, NaY) catalytic membranes were prepared and used as a flow-through catalytic membrane reactor for CO preferential oxidation (CO-PROX) in H₂-rich gas. The catalytic membranes were prepared by the modification of FAU zeolite membranes with Zr⁴⁺ and Au³⁺ by ion-exchange, then activation. The obtained catalytic membranes were characterized by using TEM, X-ray photoelectron spectroscopy, temperature-programmed reduction, and temperature-programmed desorption and their catalytic activity toward CO-PROX was tested. The results showed that the activation conditions affected the size and oxidation states of the resulting Au nanoparticles strongly, and therefore, affected the catalytic activity strongly. The catalytic activity of the Au nanoparticles can be improved by the doping of Zr to form surface oxygen vacancies and the synergetic effect of Au-Zr. Meanwhile, the presence of the zeolite framework allows the stabilization of small Au nanoparticles. The Au-Zr/FAU catalytic membrane prepared under the optimized conditions showed a high catalytic performance (CO conversion above 95 %, turnover frequency>0.4 s⁻¹) and outstanding stability (up to 450 h) below 80 °C, which made it a promising candidate for H₂ purification.