A KINETIC-MODEL FOR THE METHANOL HIGHER ALCOHOL SYNTHESIS FROM CO/CO2/H-2 OVER CU/ZNO-BASED CATALYSTS INCLUDING SIMULTANEOUS FORMATION OF METHYL-ESTERS AND HYDROCARBONS

The kinetics of the conversion of syngas (CO/CO2/H-2) to a methanol-higher alcohol mixture over a Cs-Cu/ZnO/Al2O3, catalyst were measured at a pressure of 5-100 bar, a temperature of 200-300 degrees C, a H-2/CO ratio in the feed of 0.66-4.37, a mole fraction of CO2 in the feed of 0-0.114 and a space velocity of 0.082 x 10(-3) - 2.56 x 10(-3) nm(3) s(-1) kg(cat)(-1),. Methanol was the major product and higher linear 1-alcohols (1 <n less than or equal to 7), higher branched 2-methyl-1-alcohols (4 less than or equal to n less than or equal to 9), methyl esters (2 less than or equal to n less than or equal to 4), dimethyl ether, paraffins(1 less than or equal to n less than or equal to 8), 2-methyl-paraffins (4 less than or equal to n less than or equal to 8), CO2 and H2O were analysed as significantly present secondary products. The best model available from literature predicts the obtained alcohol product distributions reasonably accurately up to (2-methyl-)1-pentanol inclusive whereafter the predictions fail completely. The predictions of the methyl esters from this model are reasonable but could be verified up to methyl propionate inclusive only. A new model is presented in this study, which is significantly more accurate than all existing models and gives accurate predictions over the entire carbon number range for both the alcohols and the methyl esters with average relative deviations of 6.7% and 4.1%, respectively. In contrast to all models from the literature, this model also incorporated the simultaneous hydrocarbon formation accurately with an average relative deviation of 9.8%. A thorough residual analysis delivers further support for the model adequacy. Finally, the alcohol and methyl ester product distributions from the literature proved to be reasonably described by this new model with average relative deviations of 22.9% and 14.1%, respectively.