Synthesis of some bifunctional catalysts and determination of kinetic parameters for direct conversion of syngas to dimethyl ether

In the present study the catalyst preparation and modeling of the reaction kinetic for syngas transformation into dimethyl ether, using a mixture of a metallic oxides (CuO, ZnO and Al2O3) and an acidic component (γ-Al2O3) as the reaction catalyst, have been presented. Twenty-three catalysts samples were prepared according to a pre-designed research program consisting of four phases. In each phase, applying the experimental design method, a number of catalysts were synthesized by the co-precipitation method, using various amounts of metal nitrates. It was noted that the ZnO content of the catalyst, the nature of the precipitant agent, mass ratio of γ-alumina to total metal oxides and calcination temperature, had the highest impacts on the activity of the catalysts. Catalysts activity and kinetic measurements were carried out using a catalytic fixed bed microreactor. The operating temperature range was 230–300 °C and the pressure was 8 bar g. The experimental runs were performed applying a wide range of catalyst mass to molar feed ratios. A kinetic expression based on methanol synthesis and dehydration of the latter was devised and correlated with the experimental results. The degree of agreement between the two sets of data was higher than 85%.