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首页> 外文期刊>Applied Surface Science >Carbon monoxide oxidation over well-defined Pt/ZrO2 model catalysts: Bridging the material gap
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Carbon monoxide oxidation over well-defined Pt/ZrO2 model catalysts: Bridging the material gap

机译：明确定义的Pt / ZrO2模型催化剂上的一氧化碳氧化：弥合材料缺口

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Four different Pt/ZrO2(C/)SiO2 model catalysts were prepared by electron beam evaporation. The morphology of these samples was examined before and after the catalytic reaction by Rutherford back-scattering (RBS), transmission electron microscopy (TEM) and grazing-incidence small-angle scattering (GISAXS). The catalytic behavior of such model catalysts was compared to a conventional Pt/ZrO2 catalyst in the CO oxidation reaction using different oxygen excess (lambda = 1 and 2). The so-called material gap was observed: model catalysts were active at higher temperature (620-770 K) and resulted in higher activation energy values (E-a = 77-93 KJ mol(-1) at lambda = 1 and 129-141 KJ mol(-1) at lambda = 2) compared to the powdered Pt/ZrO2 catalyst (370-470 K, E-a = 74-76 U mol(-1)). This material gap is discussed in terms of diffusion limitations, reaction mechanism and apparent compensation effect. Diffusion processes seem to limit the reaction on planar samples in the reactor system that was shown to be appropriate for the evaluation of the catalytic activity of powder samples. Kinetic parameters obeyed the so-called apparent compensation effect, which is discussed in detail. Langmuir-Hinshelwood-type of reaction, between COads and O-ads, was proposed as the rate-determining step in all cases. Pt particles deposited on planar structures can be used for modeling conventional powdered catalysts, even though some limitations must be taken into account. (c) 2006 Elsevier B.V. All rights reserved.
机译：通过电子束蒸发制备了四种不同的Pt / ZrO2（C /）SiO2模型催化剂。通过Rutherford背散射（RBS），透射电子显微镜（TEM）和掠入射小角散射（GISAXS）检查了催化反应前后样品的形态。在使用不同的氧气过量（λ= 1和2）的CO氧化反应中，将这种模型催化剂的催化行为与常规Pt / ZrO2催化剂进行了比较。观察到所谓的材料间隙：模型催化剂在较高温度（620-770 K）下具有活性，并导致较高的活化能值（Ea = 77-93 KJ mol（-1），λ= 1和129-141 KJ摩尔（-1）在λ= 2）与粉状Pt / ZrO2催化剂（370-470 K，Ea = 74-76 U摩尔（-1））相比。从扩散限制，反应机理和表观补偿效应的角度讨论了这种材料上的差距。扩散过程似乎限制了反应器系统中平面样品的反应，这被证明适合评估粉末样品的催化活性。动力学参数服从所谓的表观补偿效应，对此进行了详细讨论。在所有情况下，建议在COads和O-ads之间进行Langmuir-Hinshelwood型反应。即使必须考虑一些限制，沉积在平面结构上的Pt颗粒也可用于模拟常规粉末催化剂。 （c）2006 Elsevier B.V.保留所有权利。

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