Synthesis and characterization of a mesoporous silica(MCM-48)membrane on a large-pore alpha-Al2O3 ceramic tube

摘要

A mesoporous silica MCM-48 membrane was synthesized on a large-pore alpha-Al2O3 tubular support with an average pore size of 3-5 mu m by adopting the pore-prefilling method.The membranes and powders were characterized by small-angle X-ray diffraction,SEM measurement,N2 adsorption,and thermogravimetric analysis.X-ray diffraction(XRD)results showed the membrane possessed a periodic mesostructure.The N2 adsorption and desorption isotherms also showed that the membrane was a typical mesoporous material with pore channel size of about 2.7 nm.The TGA experiment proved that the removal of the surfactant is a stepwise mechanism.The permeability of the calcined mesoporous MCM-48 membrane was evaluated by the permeation of single gases(H2 and N2)with pressure drops across the membrane of 40-240 kPa.The permeation of these gases through the calcined MCM-48 membrane was strongly governed by Knudsen diffusion.The permeance of the single gas was independent of the pressure drop,indicating that there was no contribution of viscous flow to the total permeation.This result supports that there exist no large pinhole and crack in the mesoporous MCM-48 membrane,in agreement with SEM observation.