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Kinetics of propane dehydrogenation over Pt-Sn/Al2O3

机译:PT-SN/AL2O3上丙烷脱氢的动力学动力学

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The kinetics of the gas-phase dehydrogenation of propane over Pt-Sn (1 : 1 mol ratio) supported on AI2O3 was investigated for the first time over the high range of reactant/products partial pressures (up to 0.875 atm), The Ft precursor was reduced to metallic form after a temperature-programmed reduction (TPR) at 873 K. X-ray photoelectron spectroscopy (XPS) analysis suggests that a Pt-Sn surface alloy forms, decreasing the H2 adsorption on the Pt-Sn sites (5.6 nm in average size) relative to monometallic Pt (6.8 nm). We performed kinetic studies in the absence of mass/heat transfer limitations. The incorporation of Sn into Pt in Pt-Sn/Al2O3 enhanced the catalytic activity and stability when compared to Pt/Al2O3. We attribute this response to the surface electronic interaction between Pt and Sn. The initial propane consumption rate increases with the partial pressure of propane and decreases with the partial pressure of propene, while varying that of hydrogen has a negligible effect. Applying the Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach, the most likely kinetic model is non-dissociative adsorption of propane with simultaneous release of H2, where surface reaction is the rate-limiting step. Our results of the kinetic aspects provide practical insights relevant to propane dehydrogenation.
机译:首次研究了AI2O3上支持的PT-SN(1:1 mol比)的气相脱氢动力学的动力学,首次在高反应物/产物部分压力(高达0.875 atm)的高范围内,FT PROCURSOR(FT PROCURSOR)在873 K处温度填充(TPR)后,还原为金属形式。X射线光电子光谱(XPS)分析表明,PT-SN表面合金形式形式,减少了PT-SN位置的H2吸附(5.6 nm(5.6 nm)平均大小)相对于单金属PT(6.8 nm)。在没有质量/传热限制的情况下,我们进行了动力学研究。与PT/AL2O3相比,在PT-SN/AL2O3中将SN掺入Pt-SN/AL2O3中增强了催化活性和稳定性。我们将这种响应归因于PT和SN之间的表面电子相互作用。初始的丙烷消耗率随丙烷的部分压力而增加,并随丙烯的部分压力而降低,而氢的变化具有可忽略的作用。采用Langmuir-Hinshelwood-Hougen-Watson(LHHW)方法,最有可能的动力学模型是丙烷与丙烷同时释放H2的非分解性吸附,其中表面反应是速率限制步骤。我们对动力学方面的结果提供了与丙烷脱氢相关的实用见解。

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