Development of an acetylacetonate-modified silica-zirconia composite membrane applicable to gas separation

In this work, an acetylacetonate-modified equimolar SiO2-ZrO2 composite-derived membrane with molecular sieving properties was successfully fabricated. The sol-gel method was successfully employed to chemically modify zirconium tetrabutoxide prior to co-hydrolysis and -condensation with tetraethoxysilane, the resulting sol then used to fabricate a gas separation layer. An acetylacetonate-modified SiO2-ZrO2-derived membrane prepared at 300 degrees C showed H-2 permeance of 9.9. 10 7 mol m(-2) s(-1) Pa-1 with a H-2/SF6 permeance ratio of 7,600, which was a significant improvement over pure SiO2-ZrO2-derived membranes (H-2 permeance: 1.4. 10 6 mol m(-2) s(-1) Pa-1, H-2/SF6 permeance ratio: 11). Heat-treatment of an acac-modified SiO2-ZrO2-derived membrane prepared at temperatures that ranged from 250 degrees C (H-2 permeance: 4.5. 10 8 mol m(-2) s(-1) Pa-1, H-2/CH4: 100, CO2/CH4: 60, H-2/SF6: >18,000 at 50 degrees C) to 550 degrees C resulted in an improved H-2 permeance of 3.4. 10 6 mol m(-2) s(-1) Pa-1 with reduced permeance ratios (H-2/CH4: 3, H-2/SF6: 9) at 50 degrees C. A membrane prepared by heattreating a 250 degrees C-fired membrane at 300 degrees C showed the best trade-off with H-2 permeance-H2/SF6 permeance ratios above the trade-off line compared with membranes prepared at other temperatures.