Highly active CuZn/SBA-15 catalyst for methanol dehydrogenation to methyl formate: Influence of ZnO promoter

Abstract

• The catalytic performance of x CuZn/SBA-15 was dramatically superior to Cu/SBA-15. • The activity of x CuZn/SBA-15 in methanol dehydrogenation to MF was affected by ZnO amount. • The appropriate ZnO amount improved Cu dispersion and Cu 0 /(Cu 0 +Cu + ) ratio. • 10CuZn/SBA-15 exhibited most excellent activity along with favorable stability. Stable and efficient Cu/SBA-15 and x CuZn/SBA-15 ( x = 5, 10 and 15) in methanol dehydrogenation to methyl formate (MF) are prepared through a double-solvent impregnation (DI) method. Among all catalysts, 10CuZn/SBA-15 shows the highest catalytic performance with selectivity to MF about 88.1 % and methanol conversion of 31.1 %, which is attributed to the well-dispersed Cu particles and high ratio of Cu°/(Cu° + Cu + ). The proper amount of ZnO could improve dispersion of Cu because of its geometrical spacer, inhibiting growth of Cu particle, and the best dispersion is achieved in 10CuZn/SBA-15. Furthermore, the Cu°/(Cu° + Cu + ) ratio is greatly promoted with the assistance of ZnO, attributed to Cu-ZnO interaction, which reaches maxima of 53.3 % at a Cu/Zn mole ratio of 10. Specially, the optimized catalyst shows evident suitability at high temperature for methanol dehydrogenation reactions along with high level of conversion and selectivity for 100 h. Overall, our findings reveal that modification by the appropriate amount of ZnO in Cu-based catalyst has a positive impact on obtaining MF for the methanol dehydrogenation.