Comparison of ZnO-Supported Cu, Cu-Mn, Cu-Fe, Cu-Co and Cu-Ni Catalysts in CO Hydrogenation

Paper presented at the 10th International Congress on Catalysis, Budapest, 19-24th July 1992.Cu/ZnO catalysts prepared by precipitation have been modified by Mn, Fe, Co and Ni. After characterisation these have been assessed for their activity and selectivity in CO hydrogenation. The dispersion of the ternary catalysts remains similar to Cu/ZnO alone and temperature-programmed reduction suggests that the IB and VII-VIII metals are interacting in these catalysts. The conditions of reductive pretreatment of the samples critically affects their activity and selectivity in CO hydrogenation. Mn increases the rate of methanol synthesis of Cu/ZnO after reduction at suitable temperatures. However, Fe and Co decrease activity, increase alkane production and increase ethanol production, and decrease methanol production compared to Cu/ZnO. The causes of this are considered in some detail. Finally, Ni suppesses both the rate of CO hydrogenation and the selectivity to methanol of Cu/ZnO and this might be because of the formation of a partial Cu-Ni alloy. The realtive importance of Cu-Mx+ and Cu-M pairs in CO hydrogenation upon these catalysts is still the subject of discussion