Effect of support on the size and composition of highly dispersed Pt-Sn particles
Effect of support on the size and composition of highly dispersed Pt-Sn particles
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DOI：
10.1006/jcat.2002.3699
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发表时间：
2002-10-25
影响因子：
7.3
通讯作者：
Holmen, A
中科院分区：
文献类型：
--
作者：
Bednarova, L;Lyman, CE;Holmen, A
Pt和Sn沉积在γ-Al 2 O3，MgO和Mg（Al）O载体上，通过CO化学吸附和分析电子显微镜在扫描透射电子显微镜与能量色散X射线能谱（STEM/EDX）进行了研究。在1-nm范围内的单个颗粒的组合物和尺寸，并与从体积化学吸附获得的分散测量结果进行比较。我们证明，通过化学吸附测量确定的分散度可以给出不切实际的低值，可能是由金属-载体相互作用引起的，而STEM/EDX揭示了金属颗粒的正确尺寸。金属-载体相互作用似乎不存在于γ-Al_2 O_3载体上，而仅存在于Mg（Al）O和MgO载体上。丙烷脱氢催化剂的性能与金属颗粒表面Pt的含量有关。结果表明，金属粒子的组成与催化剂的活性有一定的关系。活性最高的是含有高Pt含量的金属颗粒的催化剂;然而，一些Sn对于减少焦化和可能增加稳定性是必需的。(C)2002 Elsevier Science（美国）。
Platinum and tin deposited on gamma-Al2O3, MgO, and Mg(Al)O supports were investigated by CO chemisorption and analytical electron microscopy in the scanning transmission electron microscopy with energy-dispersive X-ray spectrometry (STEM/EDX). Composition and size of individual particles in the 1-nm range are presented and results are compared with dispersion measurements obtained from volumetric chemisorption. We demonstrate that dispersion determined by chemisorption measurements can give unrealistically low values, possibly caused by metal-support interaction, while STEM/EDX reveals the correct size of metal particles. The metal-support interaction seems not to be present on gamma-Al2O3 support but only on Mg(Al)O and MgO supports. The performance of the catalyst in propane dehydrogenation is related to the amount of Pt on the metal particle surface. It is shown that there is a relationship between the composition of metal particles and the activity of the catalyst. The most active is a catalyst that contains metal particles with high Pt content; however, some Sn is necessary for reduced coking and probably for increased stability. (C) 2002 Elsevier Science (USA).