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Structure and Quantification of Edge Sites of WS2/Al2O3 Catalysts Coupling IR/CO Spectroscopy and DFT Calculations
ChemCatChem ( IF 3.8 ) Pub Date : 2020-02-25 , DOI: 10.1002/cctc.201902053 Luz Zavala‐Sanchez 1 , Ibrahim Khalil 1 , Laetitia Oliviero 1 , Jean‐François Paul 2 , Françoise Maugé 1
ChemCatChem ( IF 3.8 ) Pub Date : 2020-02-25 , DOI: 10.1002/cctc.201902053 Luz Zavala‐Sanchez 1 , Ibrahim Khalil 1 , Laetitia Oliviero 1 , Jean‐François Paul 2 , Françoise Maugé 1
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IR spectroscopy of CO adsorption (IR/CO) and Density Functional Theory (DFT) calculations on sulfide W/Al2O3 catalyst were investigated for an insight into the sulfide edge sites. Parallel between experimental and theoretical results allow to assign the ν(CO) bands at 2121 and 2066 cm−1 to CO adsorption on M‐ and S‐edge sites of WS2 phase, respectively. Through a careful analysis of CO spectra on well‐selected W catalysts, the molar attenuation coefficients for CO adsorbed on the two exposed edges could be determined. This allowed the morphology of WS2 slabs to be calculated. This work shows that increasing the W loading (6–20 wt% W) changes the slab morphology from an almost pure triangle exhibiting mostly M‐edge to a truncated triangle. On W as well as on Mo sulfide catalysts, IR spectroscopy and DFT calculation show that CO adsorption allows to account for M‐ and S‐edge sites, and thus of the morphology of sulfide slabs. It was shown that increasing the W loading shifts the slab morphology from a triangle exposing predominantly M‐edge towards a more hexagonal shape. For close to monolayer coverage of alumina, Mo and W sulfide slabs present similar shape i. e. truncated triangle. However, edge sites of WS2 slabs clearly exhibit greater stability under H2 atmosphere than Mo sulfided ones.
中文翻译：
WS2 / Al2O3催化剂的IR / CO光谱和DFT计算的边缘位点的结构和定量
研究了硫化物W / Al 2 O 3催化剂的CO吸附红外光谱（IR / CO）和密度泛函理论（DFT）计算，以了解硫化物边缘位点。实验结果和理论结果之间的平行关系允许将2121和2066 cm -1处的ν（CO）谱带分别分配给WS 2相M和S边缘位点上的CO吸附。通过对精心挑选的W催化剂上的CO光谱进行仔细分析，可以确定吸附在两个暴露边缘上的CO的摩尔衰减系数。这允许WS 2的形态要计算的平板。这项工作表明，增加W负荷（W的6-20 wt％）可以将板坯形态从几乎呈纯M形的三角形转变为截断的三角形。在W以及Mo硫化物催化剂上，红外光谱和DFT计算表明，CO吸附可以解释M-和S-edge的位点，从而可以解释硫化板的形态。结果表明，增加W载荷可使板坯形态从主要暴露M边缘的三角形变为更六角形。对于氧化铝的接近单层覆盖，Mo和W硫化平板具有相似的形状i。e。截断的三角形。但是，WS 2平板的边缘部位在H 2气氛下明显表现出比Mo硫化平板更高的稳定性。
更新日期：2020-02-25
中文翻译：
WS2 / Al2O3催化剂的IR / CO光谱和DFT计算的边缘位点的结构和定量
研究了硫化物W / Al 2 O 3催化剂的CO吸附红外光谱（IR / CO）和密度泛函理论（DFT）计算，以了解硫化物边缘位点。实验结果和理论结果之间的平行关系允许将2121和2066 cm -1处的ν（CO）谱带分别分配给WS 2相M和S边缘位点上的CO吸附。通过对精心挑选的W催化剂上的CO光谱进行仔细分析，可以确定吸附在两个暴露边缘上的CO的摩尔衰减系数。这允许WS 2的形态要计算的平板。这项工作表明，增加W负荷（W的6-20 wt％）可以将板坯形态从几乎呈纯M形的三角形转变为截断的三角形。在W以及Mo硫化物催化剂上，红外光谱和DFT计算表明，CO吸附可以解释M-和S-edge的位点，从而可以解释硫化板的形态。结果表明，增加W载荷可使板坯形态从主要暴露M边缘的三角形变为更六角形。对于氧化铝的接近单层覆盖，Mo和W硫化平板具有相似的形状i。e。截断的三角形。但是，WS 2平板的边缘部位在H 2气氛下明显表现出比Mo硫化平板更高的稳定性。
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