Al-MCM-41, [SiO2]/[Al2O3] = 30, mesoporous catalysts were synthesized using tetraethylorthosilicate (TEOS) as a source of silica and hexadecyltrimethylammonium bromide (CTAB) as a structure-directing agent (SDA) in the presence of tetrapropylammonium hydroxide (TPAOH) as a co-surfactant additive. The catalytic activities of the calcined samples were evaluated for the dehydration of methanol to dimethyl ether (DME) at 250-450 degrees C and a gas hourly space velocity (GHSV) of 14,000-80,000 mLg(cat)(-1) h(-1). Al-MCM-41 samples synthesized in the presence of TPAOH showed higher activity than those synthesized in its absence. The improvement in catalytic activity correlates with the increase in acidity brought about by the enhanced condensation of aluminosilicate framework in the Al-MCM-41 structure. Al-MCM-41 catalysts were also combined with methanol synthesis catalysts to form bifunctional catalysts for the synthesis DME from CO2/H-2 at temperature. 260 degrees C: pressure, 735 psi; GHSV, 2000 mLg(-1) (cat) h(-1) in a fixed-bed reactor. (C) 2010 Elsevier B.V. All rights reserved.