HYDROGEN PURIFICATION OF THERMOCHEMICALLY DECOMPOSED GAS-USING ZIRCONIA-SILICA COMPOSITE MEMBRANE

Hydrogen puification characteristics were measured up to 773K using composite zirconia-silica membranes coated on the surface of porous ceramic tubing for thermochemically decomposed ps. The composition of the metal alkoxides solution used successfully in the coating process was Zr(OC3H7)4:3.09, Si(OC2H5)4:7.20, Y(CH3COO)3.4H2O:0.21, i - PrOH:89.50 in mol%. With ceramic tubing supplied from TOTO Co. Ltd, 20 coatings were needed to fabricate a defect-free membrane. Separation of gaseous mixtures of H2O, HBr and H-2 Was carried out at 423-773K and it was found that HBr is concentrated on the permeation side, and H-2 does not permeate through the membrane. Permeabilities for pure gases of H-2, He, CH4, NH3, H2O, N2, O2 and CO2 were measured with trans-membrane pressures up to 0.2 MPa at 303, 423, 523 and 773K. Permeation data of water vapour shows that its main permeation mechanism is surface diffusion on the pores in the membrane.