Chemical imaging of the sulfur-induced deactivation of Cu/ZnO catalyst bodies
Chemical imaging of the sulfur-induced deactivation of Cu/ZnO catalyst bodies
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DOI：
10.1016/j.jcat.2014.04.007
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发表时间：
2014-05-01
影响因子：
7.3
通讯作者：
Weckhuysen, Bert M.
中科院分区：
文献类型：
--
作者：
Beale, Andrew M.;Gibson, Emma K.;Weckhuysen, Bert M.
研究了硫中毒对工业Cu/ZnO/Al_2 O_3催化剂体的水煤气变换活性的影响。使用化学成像方法对样品进行了表征，包括XRD-CT，XAFS映射和XRF，以了解加速硫中毒导致催化剂失活的过程。在类似于90小时的运行后，所有催化剂表现出降低的活性; H2S浓度越高，失活的程度越大。对从反应器中回收的完整样品进行的非侵入性XRD-CT测量显示了硫化物相的形成，包括闪锌矿（β-ZnS）和结晶CuS，Cu 2S和CuSO 4相。这些硫化物相主要分布为样品边缘周围的渐变电晕，对于在500 ppm H2S的最高浓度下进行的实验，达到类似于1.5 mm厚。XAFS映射，这是特别敏感的本地周围的元素被探测的协调环境，证实了混合的Cu/Zn-O/S的协调环境的存在下，样品的核心保持无硫。XRD-CT和XRF的组合显示CuS在反应条件下似乎是移动的，导致Cu朝向样品的最边缘重新分布。因此，技术的组合表明，H2S失活的Cu/ZnO/Al 2 O3催化剂体发生通过相转化的活性Cu/ZnO相成硫化物和这些组分的再分布在样品上，而不是Cu活性位点中毒的S-ads物种。(C)2014作者爱思唯尔公司出版
The effects of sulfur poisoning on the water-gas shift (WGS) activity of industrial Cu/ZnO/Al2O3 catalyst bodies have been studied. The samples were characterized using chemical imaging methods, including XRD-CT, XAFS mapping, and XRF, in order to understand the process by which accelerated sulfur poisoning leads to catalyst deactivation. After similar to 90 h on stream, all catalysts exhibited reduced activity; the higher the H2S concentration, the greater the extent of deactivation. Non-invasive XRD-CT measurements performed on intact samples recovered from the reactor revealed the formation of sulfide phases, including sphalerite (beta-ZnS) and crystalline CuS, Cu2S, and CuSO4 phases. These sulfide phases were distributed predominantly as a graduated corona around the sample edge reaching similar to 1.5 mm thick for experiments performed in the highest concentration of 500 ppm H2S. XAFS mapping, which is particularly sensitive to the local coordination environment around the element being probed, confirmed the presence of mixed Cu/Zn-O/S coordination environments and that the core of the sample remained sulfur-free. A combination of XRD-CT and XRF revealed that CuS appeared to be mobile under reaction Conditions resulting in the redistribution of Cu toward the very edge of the samples. A combination of techniques has therefore demonstrated that H2S deactivation of Cu/ZnO/Al2O3 catalyst bodies occurs via phase transformation of the active Cu/ZnO phase into sulfides and redistribution of these components over the sample instead of Cu active site poisoning by S-ads species. (C) 2014 The Authors. Published by Elsevier Inc.