Dimethyl ether synthesis from CO2 hydrogenation over hybrid catalysts: effects of preparation methods

Hybrid catalysts CuO/ZrO2 + montmorillonite K10 have been tested in the direct synthesis of dimethyl ether (DME) from CO2 + H2 mixture. The metallic function CuO/ZrO2 was synthesized by three methods i.e. citric method and NaOH or Na2CO3 co-precipitation method. The catalyst prepared with NaOH method was modified by 3 wt% of Ga, Cr, Mn and Ag. In order to determine the physicochemical properties, the following techniques were used: XRD, BET, reactive adsorption of N2O and H2TPR. All catalysts were tested in a high pressure fixed bed flow reactor under 40 atm pressure in the hydrogenation of CO2. The aim of the present study is to examine the influence of the synthesis method and calcination temperature on catalytic activity of studied catalysts. It was found that the CuO/ZrO2 prepared by citric method and calcined at 823 K is the best catalytic system. Moreover, the addition of 3 wt% Ag significantly improves selectivity to DME from 21 to 35% in comparison with undoped CuO/ZrO2.