A simple sol-gel method was adopted to synthesize boehmites with high surface area using aluminum iso-propoxide (AIP), acetic acid (AA) and 2-propanol, and the effects of surface area and methanol dehydration on activity were investigated. The hydrolysis conditions of AIP in the presence of AA in 2-propanol solvent were systematically varied to observe their effect on phase formation, crystallinity, surface area and pore size distribution of the alumina. The surface area and the number of acidic sites varied considerably with the variation in the molar ratio of AA/AIP. This study revealed that a high surface area boehmite (in the range of 628-717 m(2)/g) could be obtained by keeping the molar ratio of AA/AIP as 0.5 and that of H2O/AIP at similar to 3. Rod shaped, porous gamma-Al2O3 powder with a high surface area of 438 m(2)/g was obtained after calcination of the boehmite at 500 degrees C for 5 h in air. The temperature programmed desorption of ammonia (NH3-TPD) of the gamma-Al2O3 samples demonstrated higher concentration of acidic sites when acetic acid was used during preparation than when it was not used. The vapor phase dehydration of methanol (containing 20 mol% H2O) to dimethyl ether (DME) was conducted on the prepared aluminas. With increasing surface area of gamma-Al2O3, the temperature required to reach 50% conversion of methanol decreased due to the increased number of acidic sites which are favorable for methanol dehydration with low byproduct formation. The catalytic activity for methanol dehydration to DME correlated well with the total number of acidic sites of gamma-Al2O3, which was controlled by changing the AA/AIP and H2O/AIP molar ratios. (C) 2008 Elsevier B.V. All rights reserved.