Dynamics of Alkane Oxidation Reactions on Vanadyl Pyrophosphate Based Catalysts

本研究的目的是建立一个钒-磷-氧化物（VPO）催化剂（也称为焦磷酸钒基催化剂）上烷烃氧化的动态模型，该模型解释了催化系统中VPO晶格、VPO表面、表面和气相物质等成分如何相互作用，从而产生具有或不具有选择性的产物。该模型将包括碳氢键活化机制和氧加成机制、氧运输机制以及添加剂在决定选择性中的作用。为此，采用瞬态响应和原位光谱技术相结合的方法研究了VPO催化烷烃部分氧化的动力学过程。TAP（产品时间分析）反应器经过特殊修改，允许同时进行产品分析和原位红外或拉曼光谱。轻烷烃选择性转化为含氧化合物（醇、醚、醛、酯等）是石油化工和能源工业非常感兴趣的问题。氧合物是生产大量化学品、聚合物和塑料的中间体，也是汽油添加剂的一大需求，既可以提高辛烷值，又可以减少尾气污染物。它们通常使用VPO催化剂生产，通常来自烯烃原料。然而，烷烃（石蜡）是一种更便宜的原料，如果它们的部分氧化技术可以改进。＊＊＊

9322829 Gleaves The objective of this work is a dynamic model of alkane oxidation over vanadium-phosphorus-oxide (VPO) catalysts (also called vanadyl pyrophosphate catalysts) that explains how such components of the catalytic system as the VPO lattice, the VPO surface, surface adspecies, and gas-phase species interact to give products with or without selectivity. The model would include the mechanism of carbon-hydrogen bond activation and of oxygen addition, the mechanism of oxygen transport, and the roles of adspecies in determining selectivity. To this end, the dynamics of the partial oxidation of alkanes catalyzed by VPO are studied using a combination of transient response and in situ spectroscopic techniques. A TAP (temporal analysis of products) reactor is specially modified to permit simultaneous product analysis and in situ infrared or Raman spectroscopy. The selective conversion of light alkanes to oxygenates (alcohols, ethers, aldehydes, esters, etc.) is of great interest to the petrochemical and energy industries. Oxygenates are intermediates for production of a large array of chemicals, polymers, and plastics, and are also in great demand as gasoline additives, both to improve octane rating and to reduce tailpipe pollutants. They are often produced using VPO catalysts, usually from an olefin feedstock. However, alkanes (paraffins) are a cheaper raw material if the technology for their partial oxidation could be improved. ***