CO oxidation as a test reaction for strong metal-support interaction in nanostructured Pd/FeOx powder catalysts
CO oxidation as a test reaction for strong metal-support interaction in nanostructured Pd/FeOx powder catalysts
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DOI：
10.1016/j.apcata.2015.04.010
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发表时间：
2015-08-05
影响因子：
5.5
通讯作者：
Schloegl, Robert
中科院分区：
文献类型：
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作者：
Kast, Patrick;Friedrich, Matthias;Schloegl, Robert
通过硝酸盐前驱体的受控共沉淀方法制备了一系列不同负载的钯铁催化剂，以确保均匀的钯粒径分布。通过各种技术对预催化剂进行表征后，应用不同的受控还原条件来研究钯-铁系统内的相互作用，包括可逆和不可逆过程，如相变、SMSI、烧结和合金化。 DRIFTS、CO 化学吸附、TEM 和 XPS 测量的综合结果表明，通过强金属-载体相互作用，氧化铁物质可对 Pd 纳米粒子进行可逆表面装饰。发现此 SMSI 状态不稳定。观察到的结果与体相或钯颗粒尺寸无关。催化 CO 氧化被发现是研究该现象的合适测试反应：通过研究重复的程序升温循环中的起燃行为以及等温测量，观察到 SMSI 状态的较高活性和氧化失活。发现 Pd 分散度越高，稳定性越高。此外，通过详细的 XRD 测量研究了 Pd-Fe 系统的整体性能（如合金化）。 (C) 2015 Elsevier B.V. 保留所有权利。
A series of differently loaded palladium-iron catalysts was prepared by a controlled co-precipitation method of the nitrate precursors, in order to ensure homogeneous Pd particle size-distribution. After characterization of the pre-catalysts by various techniques, different controlled reduction conditions were applied to investigate the interactions within the Pd-iron system, containing reversible and irreversible processes like phase transformations, SMSI, sintering and alloying. Strong indications for the reversible surface decoration of the Pd nanoparticles with iron oxide species via strong metal-support interaction were found by the combined results of DRIFTS, CO-chemisorption, TEM and XPS measurements. This SMSI state was found to be unstable. It was observed independent of bulk phase or palladium particle size. Catalytic CO-oxidation was found to be a suitable test reaction for the study of the phenomenon: higher activity as well as oxidative deactivation of the SMSI state was observed by investigating the light-off behavior in repeated, temperature-programmed cycles as well as by isothermal measurements. The instability was found to be higher in case of higher Pd dispersion. In addition, bulk properties of the Pd-Fe system, like alloying, were investigated by detailed XRD measurements. (C) 2015 Elsevier B.V. All rights reserved.