Solid Superacid Catalysts Based on Tungsten Oxide

摘要CTS-9510575 这项由位于伯克利的加州大学、埃克森公司和位于墨西哥伊斯塔帕拉帕的大都会自治大学共同开展的研究涉及基于分散在氧化锆或二氧化钛表面的氧化钨的固体“超强酸”的合成和表征。 先前的工作表明，氧化锆上的氧化钨对高级烷烃的异构化具有催化活性，而不会出现其他“超强酸”引起的裂解。 为了提高催化活性，需要更高的表面积。 这项工作包括详细研究的固态过程中涉及的高表面积的锆和钛的氧化物的沉淀和钨酸盐基团在其表面上的分散。 使用X-射线衍射和吸收技术，电子显微镜，红外和拉曼光谱进行结构研究;酸位密度和化学使用现场滴定和丙烯和二甲基环己烷的催化反应进行探测。 这些研究得到了使用原位红外光谱和同位素跳跃技术的机理研究的补充。 支链烷烃作为汽油、润滑油组分和化学原料中的辛烷值增强剂具有很大的价值。 传统上，这些都是使用液体酸的几种方法之一制成的，但人们普遍认为，这些方法将很快被使用固体酸的新方法所取代。 在这一举措中寻求的优点是更容易容纳，腐蚀性更小，环境友好，和提高选择性。 这项工作得到了化学反应过程计划（CTS），固态化学和聚合物计划（DMR）和美国计划（INT）的共同支持。 ***

ABSTRACT CTS-9510575 This joint effort between the University of California at Berkeley, Exxon Corporation and the Metropolitan Autonomous University at Iztapalapa, Mexico, involves the synthesis and characterization of solid "superacids" based on tungsten oxide dispersed as isolated species, clusters, or films on the surface of zirconia or titania. Previous work has shown that tungsten oxide on zirconia has catalytic activity for isomerization of higher alkanes without the cracking caused by other "superacids". In order to improve the catalytic activity, higher surface areas are desirable. This work includes detailed study of the solid-state processes involved in the precipitation of high-surface-area zirconium and titanium oxides and in the dispersion of tungstate groups on their surfaces. Structural studies are performed using X-ray diffraction and absorption techniques, electron microscopy, and infrared and Raman spectroscopies; acid-site densities and chemistry are probed using site titrations and catalytic reactions of propylene and dimethylcyclohexane. These studies are complemented with mechanistic studies using in-situ infrared spectroscopy and isotope jump techniques. Branched alkanes have great value as octane enhancers in gasoline, lubricant components, and chemical feedstocks. Traditionally, these have been made using one of several processes employing liquid acids, but it is generally accepted that these processes will soon be replaced by new processes using solid acids. Among the advantages sought in this move are easier containment, less corrosiveness, environmental benignity, and improved selectivity. This effort is supported jointly by the Chemical Reaction Processes Program (CTS), the Solid State Chemistry and Polymers Program (DMR), and the Americans Program (INT). ***