A mesoporous silica (MCM-48) membrane: preparation and characterization

A new type of mesoporous membrane from a material with periodic structure has been developed. A membrane made of MCM-48 with a three-dimensional pore structure was deposited on a porous alumina support under hydrothermal conditions. The results of XRD and EDX elemental analysis clearly indicate that MCM-48 grew in the pores of alumina support and formed a composite layer of MCM-48/alumina. The peak intensity in the XRD pattern of the MCM-48 membrane did not decrease after calcination up to 773 K, showing that the MCM-48 membrane has high thermal stability. The as-synthesized MCM-48 membrane was gas tight for N2 at room temperature. The compactness of the calcined MCM-48 membrane was evaluated by the permeation of He, H2, CH4, O2, N2 and CO2 with pressure drops across the membrane of 100–270 kPa. The permeation of these gases through the calcined MCM-48 membrane was governed by Knudsen diffusion mechanism. The permeance of H2 was independent of the feed pressure, indicating that there was no contribution of viscous flow to the total permeation. This result supports that there existed no large pinhole in the composite layer of MCM-48/alumina.