Effect of the reduction temperature on the catalytic activity of Pd-supported catalysts

• Published in: Catalysis today 2005-10, Vol.107, p.487-492
• Main Authors: Ferrer, Victor, Moronta, Alexander, Sánchez, Jorge, Solano, Roger, Bernal, Serafín, Finol, Dora
• Format: Article
• Language: English
• Subjects: Catalysis; Chemistry; Exact sciences and technology; General and physical chemistry; Methane combustion; Pd catalysts; PdO; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; TPR
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2005.07.059

Four catalysts (0.58%Pd/Al 2O 3, 2.1%Pd/CeO 2, 7%Pd/Al 2O 3 and 7%Pd/Ce 0.8Tb 0.2O x /La 2O 3-Al 2O 3) were prepared by the incipient wetness impregnation method using aqueous solutions of Pd(NH 3) 4(NO 3) 2 and Pd(NO 3) 2. In all cases, the metallic loading was referred to as 100 g of support. The catalysts were characterized by XRD, temperature-programmed reduction (TPR) and surface area. The catalytic activity was measured using the methane combustion at 300 °C. The presence of large PdO particles was verified by the diffraction peak observed at 33.8° in the catalysts. TPR results for the 2.1%Pd/CeO 2 catalyst showed that the decoration effect of Pd by the support increased with the reduction temperature. The catalytic activity results revealed that the nature of the PdO x active phase strongly depended on both the reduction treatment and the oxygen partial pressure. The conversions for catalysts 2.1%Pd/CeO 2 (71%), 7%Pd/Al 2O 3 (79%) and 7%Pd/Ce 0.8Tb 0.2O x /La 2O 3-Al 2O 3 (80%) were higher than that of catalyst 0.58%Pd/Al 2O 3 (14%).