Hydrogen Permselective Silica Hybrid Membranes Prepared by a Novel CVD method

H2 permselective silica hybrid membranes were successfully prepared by using a novel deposition method. H2/SF6 permeances ratio was over 3000 through the membrane prepared by a PrTMOS/O3 counter diffusion CVD method at 270°C. H2 permeance through this membrane was 9.1 x 10-7 mol m-2 s-1 Pa-1 that is two orders higher than that through a silica membrane prepared by a TMOS/O2 counter diffusion CVD method at 600 °C. A high H2 permeance membrane was obtained from high O3 concentration during the deposition. Effects of deposition temperatures were investigated. Deposition temperature was important parameter to control pore size of the membrane. H2 permselctive membrane was obtained at 240°C deposition, while N2 permselective membrane was obtained at 270°C deposition. Pore size of the membranes increased with increasing the deposition temperatures upto270°C. C3H6/C3H8gas separation and C6H6/C6H12pervaporation separation were investigated using PrTMOS membranes by changing deposition conditions. The maximum C3H6/C3H8permeance ratio was 12.1 at the 320 °C permeation test. On the other hand, the maximum C6H6/C6H12separation factor was 113 at the 320 °C deposition by changing O3 flow rate. All the selectivities were considered to be a molecular sieving mechanism. Many types of the membranes were obtained by controlling the pore sizes of the membranes.