Partial Oxidation of Methane to Methanol and Formaldehyde over Molybdenum-Oxide-Based-Catalysts

研究了氧化钼催化剂的结构和表面特征与甲烷部分氧化选择性的关系。讨论的问题包括活性位点的性质、促进剂的作用、催化剂-载体的相互作用、晶格氧的作用以及气相氧化剂的参与。采用激光拉曼光谱、x射线衍射、扫描电子显微镜三维成像、能量色散x射线分析、x射线光电子能谱、稳态动力学和瞬态响应实验制备了负载型、非负载型和促进型催化剂，并对其进行了表征。利用原位激光拉曼光谱结合同位素标记研究了晶格氧在氧化反应中的作用。甲烷很容易从天然气或炼油厂废水中获得。它直接部分氧化为甲醇或甲醛，与传统的生产这些产品的方法相比，将大大节省资本和运营成本。钼氧化物催化剂有望实现这种转化，但需要进一步研究以获得实用的工艺。

The relationship between the structural and surface characteristics of catalysts based on molybdenum oxide and the selectivity of these catalysts in the partial oxidation of methane is investigated. Among the issues addressed are the nature of active sites, the effects of promoters, catalyst- support interactions, the role of lattice oxygen, and the participation of the gas-phase oxidant. Supported, unsupported, and promoted catalysts are prepared and characterized using laser Raman spectroscopy, X-ray diffraction, scanning electron microscopy with three- dimensional imaging, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, steady-state kinetics, and transient response experiments. The role of lattice oxygen in the oxidation reaction is examined using in situ laser Raman spectroscopy in conjunction with isotopic labelling. Methane is readily available from natural gas or refinery effluents. Its direct partial oxidation to methanol or formaldehyde would offer major savings in both capital and operating costs over traditional methods of making these products. Molybdenum-oxide catalysts show promise for this conversion, but further study is needed to obtain a practical process.