Genesis of Sites for n-Alkane Isomerization

拟议的研究侧重于更好地了解硫酸和钨酸盐氧化锆上轻正构烷烃(正丁烷、正戊烷和正己烷)异构化的活性中心的性质。迄今为止，氧化锆基催化剂提供了比人们所能实现的更大的利用潜力，这在很大程度上是因为它们有快速失活的趋势。正丁烷异构化的反应诱导期只持续几分钟，这在很大程度上决定了硫酸化氧化锆未来的行为。这项研究将利用一种原位反应技术，即同位素瞬时动力学分析，来确定初始反应阶段表面反应中间体的浓度和停留时间(S)的演化。在初始反应中加入微量的烯烃(1-丁烯、1-戊烯和1-己烯)将有助于确定活性中心的性质，特别是最近发现的“烯烃修饰”中心。将使用原位漂移以及其他更传统的非原位技术来表征吸附物种和所研究的催化剂。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烷烃异构化中心的异构化异构化的异构化中心的异同，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提供了用液体酸或固体酸催化剂取代不太环保的工艺的可能性，这些催化剂需要腐蚀性化合物的共同进料。

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.