Nature and Properties of a Potassium-promoted Nimo/al2o3 Water Gas Shift Catalyst
Nature and Properties of a Potassium-promoted Nimo/al2o3 Water Gas Shift Catalyst
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DOI：
10.1016/0021-9517(84)90209-4
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发表时间：
1984-06
影响因子：
7.3
通讯作者：
M. Kantschewa;F. Delannay;H. Jeziorowski-;E. Delgado;S. Eder;G. Ertl;H. Knozinger
中科院分区：
文献类型：
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作者：
M. Kantschewa;F. Delannay;H. Jeziorowski-;E. Delgado;S. Eder;G. Ertl;H. Knozinger
对传统的NiMo Al2 O3催化剂和用K2 CO3浸渍后的相同材料进行了比较研究。通过常规和微探针拉曼光谱、漫反射和X射线光电子能谱、分析电子显微镜和程序升温分解对催化剂进行了表征。用透射红外光谱研究了一氧化碳的化学吸附。结果表明，K+离子与催化剂表面有很强的相互作用。K+的存在使NiMo Al2 O3催化剂中Mo 6+的八面体配位转变为四面体配位，并使Mo 6+的还原性大大降低. KNiMo Al 2 O 3中的硫化程度似乎也降低了，这种现象伴随着Mo 5+氧化态的稳定。CO化学吸附导致在氧化态和硫化态的两种催化剂上形成碳酸盐和甲酸盐。在还原的KNiMo Al2O3上，似乎也形成了CO聚合物阴离子.考察了K+离子对NiMo Al2 O3催化剂噻吩加氢脱硫、乙烯加氢、CO甲烷化和水煤气变换反应性能的影响。在K+离子存在下，HDS的活性显著降低，而WGS的活性同时增强。并试图将K2CO3浸渍引起的钼物种结构、对称性和价态的变化与催化性能的变化联系起来。
A comparative study has been performed of a conventional NiMo Al 2 O 3 catalyst and of this same material after impregnation with K 2 CO 3. The catalysts were characterized by conventional and microprobe Raman spectroscopy, diffuse reflectance and X-ray photoelectron spectroscopy, analytical electron microscopy and temperature-programmed decomposition. The chemisorption of carbon monoxide was studied by transmission infrared spectroscopy. The results indicate a very strong interaction of K+ ions with the catalyst surface. The original octahedral coordination of Mo 6+ in the NiMo Al 2 O 3 catalyst is transformed into a tetrahedral coordination and the reducibility of Mo 6+ is strongly decreased in the presence of K+ ions. Also the degree of sulfidation seems to be reduced in KNiMo Al 2 O 3, this phenomenon being accompanied by a stabilization of the Mo 5+ oxidation state. CO chemisorption leads to the formation of carbonates and formates on both catalysts in their oxidized and sulfided states. On reduced KNiMo Al 2 O 3 CO polymer anions also seem to be formed. The effect of K+ ions on the catalytic performance of the NiMo Al 2 O 3 catalysts was tested for thiophene hydrodesulfurization (HDS), ethylene hydrogenation, CO methanation, and water gas shift (WGS). A significant reduction in activity was observed for HDS in the presence of K+ ions, while the activity for WGS was simultaneously enhanced. An attempt is made to correlate the changes of the catalytic performance with the changes which are induced by K 2 CO 3 impregnation on structure, symmetry, and valence state of the molybdenum species.