On the Kinetic of LPDME Process over Bi-Functional Catalyst in N-Hexadecane

Abstract

The intrinsic kinetics of the three phase dimethyl ether (DME) synthesis from syngas over a bi- functional catalyst has been investigated in an agitated slurry reactor at 20-50 bar, 200-240 °C and H2/CO feed ratio from 1 to 2. The bi-functional catalyst was prepared by physical mixing of CuO/ZnO/Al2O3 as methanol synthesis catalyst and H-ZSM-5 as methanol dehydration catalyst. The three reaction including methanol synthesis from CO and H2, methanol dehydration to dimethyl ether (DME) and water-gas shift reaction were chosen as the independent reactions. A kinetic model for the combined methanol + DME synthesis based on a methanol synthesis model proposed by Graaf and a methanol dehydration model by Bercic and Levec have been fitted our experimental data. Coefficients in the equations follow the Arrhenius and Van't Hoff relation. The calculated apparent activation energy of the methanol synthesis reaction and methanol dehydration reaction are 86.1 and 71.37 kJ/mol, respectively. Furthermore, slurry liquid (Hexadecane) affects the activity of the catalyst via interaction between liquid and adsorbed surface species and competitive adsorption of a solvent onto the catalyst carrier will reduce the reaction rate insignificantly.