Nanoscale tailoring on thin bimetallic organo-oxide membranes for H2/CO2 separation

The design of tailored novel membrane networks with excellent hydrothermal stability allowing gas sieving is highly desired to take them a step closer to large scale commercialization for energy efficient separation. Bistriethoxysilylmethane (BTESM) containing Si-C-Si bonds was used as a precursor for the fabrication of Tiincorporated BTESM organosilica membranes on a macroporous ceramic support with a mesoporous intermediate layer. The precise engineering on the sol-gel parameters allowed the formation of bimetallic clusters with 2-4 nm size range in the clear organo-oxide sols. XPS analyses indicated the development of Si-O-Ti connections in the organo-oxide membrane network. A high H-2 permeance of 6.3 x 10(-7) mol/m(2)sPa and attractive ideal selectivities of 10, 10, 119 and 222 for H-2/N-2, H-2/CH4, H-2/C3H6 and H-2/C3H8, respectively are attained from an exceptionally thin BTESM membrane. H-2/CO2 ideal selectivity increases from 4 to 8 upon incorporation of 15 mol% Ti into membrane network while selectivities increase to 32 for H-2/N-2, 44 for H-2/CH4, and 246 for H-2/C3H8 with 1.25-fold increase in H-2 permeance. H-2/CO2 ideal selectivity of 24 was achieved with moderate H-2 permeance of 1.7 x 10(7) mol/m(2)sPa after hydrothermal treatment for 45 h for BTESM15 membrane as thin as 65 nm. This is the one of the thinnest ceramic supported organosilica membrane reported having acceptable H-2 permeance after hydrothermal treatment.

Automated summary

Tailored novel membrane networks with excellent hydrothermal stability are desired for gas sieving applications. Ti-incorporated BTESM organosilica membranes show high H-2 permeance and ideal selectivities for various gas pairs.