Catalytic and Structural Studies of Mixed Silver-Copper Oxides (P3.40)
Recently synthesized mixed silver-copper oxides (Ag2Cu2O3 and Ag2Cu2O4) are interesting objects for catalytic applications owing to its unique crystal structure. In this work the structural features and catalytic properties of Ag2Cu2Ox oxides were studied in detail. To test catalytic activity the reactions of total and partial oxidation were used. The combination of physicochemical techniques was applied to characterize the reaction properties, surface composition and structural features of mixed oxides. Using in situ studies the influence of reaction treatment on the surface and crystal structure of mixed oxides was investigated. Both Ag2Cu2O3 and Ag2Cu2O4 oxides possessed high catalytic activity in low temperature CO oxidation. Under C2H4 epoxidation conditions mixed silver-copper oxides reached the high value of C2H4O selectivity (up to 25%). This was related to the formation of Ag°/CuO composite catalyst as a result of Ag2Cu2Ox decomposition during reaction exposure.
Mixed silver-copper oxides Ag2Cu2O3 and Ag2Cu2O4 were prepared and characterized as catalysts for CO oxidation and C2H4 epoxidation. The reversible redox transition Cu2+↔Cu1+ with the participation of Cu-O1-Cu-type oxygen may be crucial for catalytic CO oxidation on the Ag2Cu2O3 surface at low temperature. In case of Ag2Cu2O4 high catalytic activity at room temperature was caused by the presence of unusual oxidized copper and silver species. Both mixed oxides demonstrated activity in ethylene epoxidation reaction with C2H4O selectivity up to 25%. Such high values of selectivity related to the formation of Ag0/CuO composite catalyst after the treatment of mixed oxides by reaction medium during catalytic measurements.