Selective Electrophilic Substitution of Halogens into Alkyl-Aromatics using ZSM-5

9321392隆德 本文研究了ZSM-5分子筛作为甲苯氯化反应催化剂的性能。 在三种可能的一氯化产物中，对氯甲苯是最有价值的;在涉及烷基芳烃的其他反应中，ZSM-5对帕拉异构体的形成具有选择性。 在这项工作中，使用了其中铁阳离子存在于沸石的离子交换位置的ZSM-5形式。 研究的第一个（按时间顺序）目的是确定催化剂在反应条件下是否失活，如果是，则测量失活的严重程度并确定其来源。 第二个目标是使用吸附能力和选择性、穆斯堡尔谱、吸附物质的红外光谱、透射电子显微镜、酸度测量、化学分析、离子交换和其他技术来探测活性位点。 催化剂的制备具有不同的脱水程度、铁的位置和硅/铝比。 进行反应器研究以测量催化活性和选择性。 第三个目标是从稳态和瞬态动力学测量和程序升温脱附数据开发反应动力学的机理微观动力学模型。 ZSM-5的性能进行了定量比较，传统的路易斯酸催化剂。 氯化反应和相关的芳香取代反应广泛应用于化学生产中。 目前，它们使用相对大量的廉价（并且不是非常活性的）催化剂来完成，这些催化剂产生大量的固体废物，这现在被认为是一个环境问题。 这项工作的目的是取代这些过程与那些采用少量的更活跃的催化剂，是相对良性的环境。 ***

9321392 Lund This is a study of the zeolite ZSM-5 as a catalyst for the chlorination of toluene. Of the three possible monochlorination products, p-chlorotoluene is the most valuable; in other reactions involving alkylaromatics, ZSM-5 is selective for formation of the para isomer. In this work, a form of ZSM-5 in which iron cations are present in ion-exchange positions of the zeolite is used. The first (chronologically) objective of the study is to determine whether the catalyst deactivates under reaction conditions, and if so, to measure the severity of the deactivation and determine its origin. The second objective is to probe the active site using sorption capacity and selectivity, Mossbauer spectroscopy, infrared spectroscopy of adsorbed species, transmission electron microscopy, acidity measurements, chemical analysis, ion exchange, and other techniques. Catalysts are prepared with various degrees of dehydration, location of iron, and silicon/aluminum ratios. Reactor studies are performed to measure catalytic activity and selectivity. The third objective is to develop a mechanistic microkinetic model of the reaction kinetics from steady-state and transient kinetics measurements and temperature-programmed desorption data. The performance of ZSM-5 is compared quantitatively to that of conventional Lewis-acid catalysts. Chlorinations and related aromatic substitution reactions are widely used in chemical manufacturing. They are presently done using relatively large amounts of inexpensive (and not very active) catalysts that create large amounts of solid waste that is now recognized to be an environmental problem. This work aims to replace such processes with ones that employ small amounts of more active catalysts that are relatively benign environmentally. ***