XPS and TPR examinations of γ-alumina-supported Pd-Cu catalysts

• Published in: Applied catalysis. A, General General, 2001-01, Vol.206 (1), p.113-124
• Main Authors: Batista, Jurka, Pintar, Albin, Mandrino, Djordje, Jenko, Monika, Martin, Vincent
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Pd-Cu bimetallic clusters; Supported Pd-Cu catalysts; Temperature-programmed reduction (TPR); Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; X-ray photoelectron spectroscopy (XPS); γ-Kind alumina
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/S0926-860X(00)00589-5

Alumina-supported palladium-copper catalysts, which promote liquid-phase nitrate reduction, have been prepared according to different impregnation sequences of γ-Al 2O 3 support and characterized by X-ray photoelectron spectroscopy (XPS), X-ray induced Auger electron spectroscopy (XAES) and temperature-programmed reduction (TPR). Analysis of Pd XPS/XAES spectra reveals that palladium is present on the γ-alumina support in the metallic form. Copper is reduced at lower temperatures in the presence of palladium particles compared to the CuO/γ-Al 2O 3 sample. Due to the low copper content in catalysts ( σ Cu≈10 14 atoms cm −2), the XPS/XEAS spectral features of reduced copper species are quite different from those of bulk copper. As shown by TPR and XPS/XAES data, formation of highly dispersed Pd-Cu bimetallic clusters is suggested. It was discovered by means of TPR analysis that the catalyst preparation in which the γ-alumina support is impregnated first by copper salt, results in higher formation of the Pd-Cu alloy.