Porous silica membranes with different pore sizes (average pore size: 0.3-1.2 nm) and surface chemistry were prepared from SiO2, steam-treated SiO2, SiO2 AZrO(2), and SiO2-ATiO(2) by sol-gel processing, and were applied to the pervaporation (PV) separation of methanol (MeOH) /dimethyl carbonate (DMC) mixtures at 50 degrees C. Although SiO2 AZrO(2) membranes demonstrated a separation factor of <10, the SiO2 porous membranes had an increased separation factor from 10-160. Silica membranes with an average pore size of 0.3 nm showed the highest permselectivity of methanol with a separation factor of 140 and a methanol flux of 180 mol/(m(2)h) for MeOH 50 mol% at 50 degrees C. To characterize the surface property of SiO2 membranes, SiO2 powdered samples were used for an adsorption experiment of vapor (MeOH, DMC) in single and mixed systems, revealing increased MeOH selective adsorption for SiO2 powders with hydrophilic and small pores, which was consistent with PV performance. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 2079-2089, 2011