For Better Industrial Cu/ZnO/Al2O3 Methanol Synthesis Catalyst: A Compositional Study

Abstract

A series of industrial related Cu/ZnO/Al2O3 methanol catalysts with different compositions were prepared by parallel coprecipitation method at neutral condition. The structural properties were characterized through BET, XRD, TEM, TPD and TPR, and the catalytic performances were evaluated on a 4-tube stainless steel continuous flow fixed-bed microreactor. The influence of composition on performances was investigated. The results show that Al2O3 increases the long-term stability of catalysts due to stabilizing effect, meanwhile, Al also promotes the formation of zincian malachite phase as the precursor during coprecipitation and aging. Furthermore, Al2O3 surface acidity also affects the byproducts selectivity. Cu/Zn ratio influences the activity of catalysts which could be traced back to precursor phases. ZnO also affects the long-term stability probably derived from its spacing effect. Taking activity, long-term stability and product purity all into consideration, an optimized composition was found to be with 2.8 ≤ n(Cu)/n(Zn) ≤ 3.0 and 10 ≤ n(Al) ≤ 12, over which the performances are better than that of commercial C307 catalyst in our experiments.