抄録
Gas permeation properties through silica based metal-doped microporous membranes prepared by the sol-gel method were investigated. In order to control pore size and affinity with permeating gas molecules, especially with CO2 for CO2/N2 gas separation membranes, nitrates of Ni, Al, Mg metals, and ammonium salt of vanadium were added to silica colloidal solutions. The molar ratio of additives, Si/M was 9/1. CO2 and N2 adsorption measurements on pure silica and metal-doped silica powder samples were conducted to estimate the affinity of the membrane materials with those gases. Pure silica and Ni-doped silica showed the largest amount of adsorbed CO2. Ni-doped silica membranes showed no attract difference from a typical pure silica membrane for temperature dependencies of gas permeance, while Mg-doped silica membranes might have relatively smaller effective pores for CO2/N2 separation and the value of permeance ratio of 57 could be obtained at 50 ℃. On the other hand, V-doped silica membranes had larger pores and N2 gas permeance increased with decreasing temperature, which would result in lower performance of CO2 separation. Concerning the Al-doped silica membranes, the affinity with CO2 decreased by addition of Al. In addition, activation energy of He and H2 for permeation on Al-doped membranes became greater, which suggested densification of silica network because of Al dispersion in the dense phase.
