Fabrication of Pd-Nb bimetallic doped organosilica membranes by different metal doping routes for H_(2)/CO_(2) separation

Monometallic doping has proved its superiority in improving either permselectivity or H_(2) permeability of organosilica membranes for H_(2)/CO_(2) separation,but it is still challenging to break the trade-off effect.Herein,we report a series of Pd-Nb bimetallic doped 1,2-bis(triethoxysilyl)ethane(Pd-Nb-BTESE,PNB)membranes with different metal doping routes for simultaneously improving H_(2) permeance and H_(2)/CO_(2) permselectivity by the synergetic effects of Pd and Nb.The doped Pd can exist in the BTESE network as nanoparticles while the doped Nb is incorporated into BTESE network forming Nb-O-Si covalent bonds.The metal doping routes significantly influence the microstructure of PNB networks and gas separation performance of the PNB membranes.We found that the PNB membrane with Pd doping priority(PNB-Pd)exhibited the highest surface area and pore volume,comparing with Nb doping priority(PNB-Nb)or Pd-Nb simultaneous doping(PNB-PdNb).The PNB-Pd membrane could not only exhibit an excellent H_(2) permeance of~10^(−6) mol·m^(−2)·s^(−1)·Pa^(−1) but also a high H_(2)/CO_(2) permselectivity of 17.2.Our findings may provide novel insights into preparation of bimetallic doped organosilica membranes with excellent H_(2)/CO_(2) separation performance.