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Surface studies of planar model HDN catalysts.

机译：平面模型HDN催化剂的表面研究。

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摘要

Model catalysts based on oxidized Mo, and formed on planar supports, have been studied by x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES) and secondary electron microscopy (SEM). The reason for using planar catalysts is to reduce the effects of uncertainties that may occur, as a result of differential charging, when direct measurements are made on real catalysts. The model catalyst approach is designed to provide new information about the chemistry which takes place during the preparation stages of real catalysts. It is hoped that the observations made here may help to understand behaviors for high-area supported Mo catalysts.;Alumina supported molybdena model catalysts, prepared by wet deposition of ammonium molybdate on oxide-coated planar Al, were studied as a function of calcination temperature (200, 350 and 450°C). Characterizations by XPS, SIMS and SEM indicate that the Mo disperses more uniformly on the support when the heating was done at 450°C as opposed to the lower temperatures.;Comparative sulfidabilities of these model catalysts (i.e. the uncalcined form and those calcined at 200, 350 and 450°C) were assessed by XPS. The Mo dispersion affects the sulfiding of the samples calcined at lower temperatures, and in particular the amount of Mo(+4) sulfide formed through the treatment with H2S is greater when the Mo is better dispersed on the initial sample.;Reaction pathways associated with the nitridation by NH3 of MoO3 thin films, formed on a Mo substrate, were studied by XPS. Core level and valence spectra are consistent with the MoO3 being reduced, but the degree of reduction depends on the reaction temperature.;The nitridation of MoO3 samples formed on alumina and silica supports have also been characterized by XPS, and comparisons made with behavior for the NH3 reaction with MoO3/Mo. The samples on the oxide supports appear to show easier O-N replacement compared with the MoO 3/Mo system. In general, the reduction behavior for MoO3/AlO x is similar to that of MoO3/Mo, but the metal in MoO 3/SiO2 is more easily reduced (Mo(0) is detected after the reaction with NH3 on the SiO2 system but not on AlOx). (Abstract shortened by UMI.).
机译：通过X射线光电子能谱（XPS），二次离子质谱（SIMS），俄歇电子能谱（AES）和二次电子显微镜（SEM）研究了基于氧化Mo并形成在平面载体上的模型催化剂。使用平面催化剂的原因是为了减少在实际催化剂上进行直接测量时由于电荷差异而可能出现的不确定性的影响。模型催化剂方法旨在提供有关在实际催化剂制备阶段发生的化学反应的新信息。希望这里的观察结果可以帮助理解高面积负载的Mo催化剂的行为。研究了通过将钼酸铵湿法沉积在氧化物包覆的平面Al上制备的氧化铝负载的钼模型催化剂与煅烧温度的关系（200、350和450°C）。 XPS，SIMS和SEM的表征表明，与在较低温度下进行加热相比，在450°C加热时，钼在载体上的分散更均匀。;这些模型催化剂的比较硫化性（即未煅烧形式和在200℃煅烧的形式） ，350和450°C）通过XPS进行评估。 Mo分散会影响在较低温度下煅烧的样品的硫化，特别是当Mo更好地分散在初始样品上时，通过用H2S处理形成的Mo（+4）硫化物的量更大。利用XPS研究了在Mo衬底上形成的MoO3薄膜的NH3氮化作用。核心能级和化合价谱与还原的MoO3一致，但还原的程度取决于反应温度。; XPS还对在氧化铝和二氧化硅载体上形成的MoO3样品的氮化进行了表征，并对其行为进行了比较。 NH3与MoO3 / Mo反应。与MoO 3 / Mo系统相比，氧化物载体上的样品似乎显示出更容易的O-N置换。通常，MoO3 / AlO x的还原行为与MoO3 / Mo相似，但是MoO 3 / SiO2中的金属更易于还原（在SiO2系统上与NH3反应后检测到Mo（0），但不是在AlOx上）。 （摘要由UMI缩短。）。

著录项

  • 作者

    Leung, Yin-Ling.;

  • 作者单位

    The University of British Columbia (Canada).;

  • 授予单位 The University of British Columbia (Canada).;
  • 学科 Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 169 p.
  • 总页数 169
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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