67.
Combustion of CO, ethyl acetate and ethanol was studied over CuO
x/Al
2O
3, CuO
x–CeO
2/Al
2O
3, CuMn
2O
4/Al
2O
3 and Mn
2O
3/Al
2O
3 catalysts. It was found that modification of the alumina with ceria before subsequent copper oxide deposition increases the activity for combustion of CO substantially, but the effect of ceria was small on the combustion of ethyl acetate and ethanol. The activity increases with the CuO
x loading until crystalline CuO particles are formed, which contribute little to the total active surface. The CuO
x–CeO
2/Al
2O
3 catalyst is more active than the CuMn
2O
4/Al
2O
3 catalyst for the oxidation of CO but the CuMn
2O
4/Al
2O
3 catalyst is more active for the combustion of ethyl acetate and ethanol.
Thermal ageing and water vapour in the feed caused a modest decrease in activity and did not affect the CuOx–CeO2/Al2O3 and CuMn2O4/Al2O3 catalysts differently. In addition, no difference in intermediates formed over the two catalysts was observed.
Characterisation with XRD, FT-Raman and TPR indicates that the copper oxide is present as a copper aluminate surface phase on alumina at low loading. At high loading, bulk CuO crystallites are present as well. Modification of the alumina with ceria before the copper oxide deposition gives well dispersed copper oxide species and bulk CuO crystallites associated to the ceria, in addition to the two copper oxide species on the bare alumina. The distribution of copper species depends on the ceria and copper oxide loading. The alumina supported copper manganese oxide and manganese oxide catalysts consist mainly of crystalline CuMn2O4 and Mn2O3, respectively, on Al2O3. 相似文献