Palladium-niobium bimetallic doped organosilica membranes for H₂/CO₂ separation

In this work, high-performance palladium-niobium doped 1,2-bis(triethoxysilyl)ethane (Pd–Nb-BTESE) membranes were prepared for H₂/CO₂ separation by using the sol-gel method. Nb was first incorporated into the organosilica networks in the form of Nb–O–Si covalent bonds, while Pd nanoparticles were successfully embedded into the networks with size of 5–10 nm. Based on the synergetic effects of Pd–Nb doping, the as-prepared membranes showed more appropriate structures for H₂/CO₂ separation. By controlling the same doping amount of Nb and changing Pd doping contents (n (Pd): n(Si) = 0.05–0.4), we found that the Pd–Nb-BTESE membrane with higher Pd doping content showed higher H₂/CO₂ permselectivity and stronger H₂ adsorption capacity. The H₂/CO₂ separation performance of all the prepared Pd–Nb-BTESE membranes surpass the upper bound 2008. The membrane with n (Pd): n (Si) of 0.4 showed a superior H₂/CO₂ permselectivity of 107 and a high H₂ permeance of 1.12 × 10⁻⁷ mol m⁻² s⁻¹·Pa⁻¹. Our findings provide novel insights into tailoring and functionalizing organosilica membranes through bimetallic doping for practical applications.