Genesis of Sites for n-Alkane Isomerization

提出的研究重点是更好地了解硫酸盐氧化锆和钨氧化锆上轻正构烷烃（正丁烷、正戊烷和正己烷）异构化的活性位点的性质。迄今为止，氧化锆基催化剂的利用潜力比能够实现的要大，这在很大程度上是由于它们具有快速失活的趋势。正丁烷异构化反应的诱导期仅持续几分钟，这在很大程度上决定了硫化氧化锆的未来行为。本研究将利用原位反应技术——同位素瞬态动力学分析（ITKA），来确定初始反应期间表面反应中间体浓度和停留时间的演变。在初始反应中加入微量的烯烃（1-丁烯、1-戊烯和1-己烯）将有助于确定活性位点的性质，特别是最近确定的“烯烃修饰”位点。原位漂移以及其他更传统的非原位技术将用于表征吸附物质和所研究的催化剂。教育部分将是对研究生和本科生的传统指导。更好地了解这些催化剂上不同正构烷烃异构化位点的异同点，可以指导设计更稳定的催化剂。围绕使用这种固体酸催化剂建立的工艺为用液体酸或需要腐蚀性化合物共同进料的固体酸催化剂取代不太环保的工艺提供了可能性。

The proposed research focuses on developing a better understanding of the nature of the active sites on sulfated- and tungstated zirconias for the isomerization of light n-alkanes (n-butane, n-pentane, and n-hexane). To date, zirconia-based catalysts have offered more potential for utilization than has been able to be realized, in large part due to their tendency towards fast deactivation. The reaction induction period, lasting only a few minutes for n-butane isomerization, largely determines the future behavior of sulfated zirconia. The proposed research will make use of an in-situ reaction technique, isotopic transient kinetic analysis (ITKA), to determine the evolution of the concentration and residence time(s) of the surface reaction intermediates during the initial reaction period. Addition of trace amounts of olefins (1-butene, 1-pentene, and 1-hexene) during initial reaction will help to define the nature of the active sites, and in particular "olefin-modified" sites that have recently been identified. In-situ DRIFTS as well as other more traditional ex-situ techniques will be used to characterize adsorbed species and the catalysts studied. The educational component will be the traditional mentoring of graduate and undergraduate students. A better understanding of the similarities and differences of the sites on these catalysts for the isomerization of the different n-alkanes may guide the design of more stable catalysts. Processes built around the use of such solid acid catalysts offer possibilities for replacing less environmentally friendly processes with liquid acids or solid acid catalysts requiring the co-feed of corrosive compounds.