Redox behavior of gold supported on ceria and ceria-zirconia based catalysts
来源期刊：JOURNAL OF RARE EARTHS2009年第2期
论文作者：Carla de Leitenburg Marta Boaro Alessandro Trovarelli Jordi Llorca Michela Vicario
Key words：gold; ceria; zirconia; catalysis; reduction behaviour; nanoparticles; temperature programmed reduction; X-ray diffraction; rare earths;
Abstract: A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions (0.28≤x≤1.00). The morphological and structural characterization of these catalysts were carried out with X-ray diffraction, trans-mission electron microscopy (TEM) analysis and physical adsorption technique, and their redox properties were studied by temperature pro-grammed reduction using both H2 and CO as probe molecules. Two cycles of oxidation/reduction were carried out in order to evaluate the effects of redox aging and gold sintering on the oxygen exchange capability. As observed with other noble metals, gold enhanced and pro-moted the ceria reduction at lower temperatures. Reduction by CO was shown to be dependent on the fine dispersion of gold and to be nega-tively affected by the ageing process more than reduction with hydrogen. This might have implications in reactions like water gas shift and CO-PROX which involve CO as a main reactant.
Carla de Leitenburg1，Marta Boaro1，Alessandro Trovarelli1，Jordi Llorca2，Michela Vicario3
(1.Dipartimento di Scienze e Tecnologie Chimiche,Universitá di Udine,Via del Cotonificio 108,33100 Udine,Italy;
2.Institut de Tècniques Energètiques,UniversitatPolitècnica de Catalunya,Diagonal 647,ed.ETSEIB,08028 Barcelona,Spain;
3.Dipartimento di Scienze e Tecnologie Chimiche,Università di Udine,Via del Cotonificio 108,33100 Udine,Italy)
Abstract:A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions (0.28≤x≤1.00). The morphological and structural characterization of these catalysts were carried out with X-ray diffraction, trans-mission electron microscopy (TEM) analysis and physical adsorption technique, and their redox properties were studied by temperature pro-grammed reduction using both H2 and CO as probe molecules. Two cycles of oxidation/reduction were carried out in order to evaluate the effects of redox aging and gold sintering on the oxygen exchange capability. As observed with other noble metals, gold enhanced and pro-moted the ceria reduction at lower temperatures. Reduction by CO was shown to be dependent on the fine dispersion of gold and to be nega-tively affected by the ageing process more than reduction with hydrogen. This might have implications in reactions like water gas shift and CO-PROX which involve CO as a main reactant.
Key words:gold; ceria; zirconia; catalysis; reduction behaviour; nanoparticles; temperature programmed reduction; X-ray diffraction; rare earths;
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