EFFECT OF HEAT-TREATMENT CONDITIONS ON CU-CR GAMMA-ALUMINA CATALYST FOR CARBON-MONOXIDE AND PROPENE OXIDATION/

The activity behavior of carbon monoxide and propene oxidation on Cu-C r catalysts was investigated by varying both the catalyst composition and the heat-treatment conditions. gamma-Alumina supported CuO, Cr2O3 and Cu-Cr oxide catalysts were employed. The Cu-Cr catalysts were trea ted by heating at 300-900 degrees C under oxidizing or reducing atmosp here. Calcined at 700-900 degrees C under oxidizing atmosphere, the fo rmation of Cu2Cr2O4 spinel structure resulted in an enhanced activity not only for carbon monoxide oxidation but also for propene oxidation. On the other hand, treatment in a reducing atmosphere at 700-900 degr ees C produced a sintered copper surface but induced a strong metal-su pport interaction that led to an enhancement in activity, but only for carbon monoxide oxidation. Additionally, the synergistic effect resul ting from the ligand effect, as Cr2O3 species is closely associated wi th CuO species, occurs for carbon monoxide oxidation, The activity of propene oxidation on the CuO catalyst reaches a maximum at a copper co ntent of about 10 wt.-% and that on the Cr2O3 catalyst reaches a maxim um at a chromium content of about 25 wt.-%.