Direct synthesis of dimethyl ether (DME) from syngas was investigated over a series of hybrid catalytic systems containing a Cu-based methanol synthesis component with varying amounts of ZnO and MgO, and gamma-Al2O3 as a methanol dehydration component. Methanol synthesis and methanol dehydration components were homogeneously mixed in a 2:1 weight ratio to prepare the hybrid catalysts, which were characterized by transmission electron microscopy, scanning electron microscopy, BET surface area analysis, powder X-ray diffraction, NH3 temperature-programmed desorption, and H-2 temperature programmed reduction methods. The syngas-to-DME (STD) reaction was studied in an isothermal fixed bed reactor at 30 bar and 260 degrees C. The catalysis results revealed improved effectiveness of the catalyst in the presence of 20 mol% MgO, enabling a significant enhancement in CO conversion from 19% to 37% and in DME selectivity from 36% to 83%, as compared with the activity of a catalyst without MgO. By-product CO2 and C-1 and C-2 hydrocarbon selectivity was also decreased from 48% to 14% for CO2 and from 8% to 2.5% for hydrocarbons. Catalyst performance, CO conversions and DME selectivity were evaluated by varying the reaction temperature, pressure, space velocity and H-2/CO ratio in syngas. XRD data revealed the formation of a good crystalline malachite structure for the catalysts containing up to 20 mol% MgO, but the crystallinity in the structure was lost when 30% MgO was added, resulting in decreased catalytic activity. (C) 2015 Elsevier Inc. All rights reserved.