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

Abstract

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 °C showed H2 permeance of 9.9 × 10 −7 mol m−2 s−1 Pa−1 with a H2/SF6 permeance ratio of 7,600, which was a significant improvement over pure SiO2–ZrO2-derived membranes (H2 permeance: 1.4 × 10 −6 mol m−2 s−1 Pa−1, H2/SF6 permeance ratio: 11). Heat-treatment of an acac−-modified SiO2–ZrO2-derived membrane prepared at temperatures that ranged from 250 °C (H2 permeance: 4.5 × 10−8 mol m−2 s−1 Pa−1, H2/CH4: 100, CO2/CH4: 60, H2/SF6: >18,000 at 50 °C) to 550 °C resulted in an improved H2 permeance of 3.4 × 10−6 mol m−2 s−1 Pa−1 with reduced permeance ratios (H2/CH4: 3, H2/SF6: 9) at 50 °C. A membrane prepared by heat-treating a 250 °C-fired membrane at 300 °C showed the best trade-off with H2 permeance-H2/SF6 permeance ratios above the trade-off line compared with membranes prepared at other temperatures.