Partial oxidation of methane over bimetallic copper–cerium oxide catalysts

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2010-04, Vol.320 (1), p.47-55
• Main Authors: Ferreira, Ana C., Ferraria, A.M., do Rego, A.M. Botelho, Gonçalves, António P., Girão, A. Violeta, Correia, Rosário, Gasche, T. Almeida, Branco, Joaquim B.
• Format: Article
• Language: English
• Subjects: Bimetallic; Catalysis; Catalytic partial oxidation; Chemistry; Copper–cerium oxide; Exact sciences and technology; General and physical chemistry; Methane; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2009.12.014

Bimetallic copper–cerium oxide catalysts were obtained by two routes using either the intermetallic compound CeCu 2 or the sol–gel reaction in the presence of urea. The structure and morphology of the copper–cerium oxides particles were significantly different depending on the synthetic method. The catalysts performance was investigated for the catalytic partial oxidation of methane (POM). The activity and selectivity of 2CuO·CeO 2 (intermetallic route sample) was comparable to that of noble metals, e.g. 5 wt% Rh/Al 2O 3, and stable for a large period of time on stream. The interaction between copper and cerium oxide phases seems to be responsible for such good catalytic behavior, which is a direct consequence of the synthetic method used in this work. The performance of bimetallic copper–cerium oxides was investigated for the catalytic partial oxidation of methane. They were synthesized by two routes using either the intermetallic compound CeCu 2 as catalytic precursor or the sol–gel method via cerium and copper nitrates (1:2) in the presence of urea. The catalysts prepared by the sol–gel method were always less active and selective than the catalyst prepared by the intermetallic route, which was comparable in catalytic behavior to noble metal catalysts on alumina (e.g. 5 wt% Rh/Al 2O 3, Conv. CH 4 > 90%, Sel. H 2 > 99%, H 2/CO ≈ 2.0) at T = 750 °C. To our knowledge, this is a novelty for copper based catalysts. The copper–cerium oxide catalysts were also quite stable in the temperature range studied, 350–800 °C, and for a long period of time on stream. Such catalytic behavior seems to be determined by the surface morphology and composition and by an unusual interaction between the copper and cerium oxide that hinders the deactivation of the catalyst at high temperatures, which is a direct consequence of the synthetic method used in this work. Therefore, the bimetallic copper–cerium oxide catalyst obtained by the intermetallic route seem to be a good option to produce syngas with the advantage of being less expensive than the catalysts based on noble metals.