Bond Breaking and Rearrangement

Control of the multitude of pathways which feed molecules can take is the primary objective of aU catalyst and process developments. The work covered in this chapter focuses primarily on describing the approaches in material and catalysis development which have led to major advances in zeolite application in hydrocarbon conversion. The breaking and formation of carbon-carbon and carbon-hydrogen bonds constitute the majority of the chemical transformations involved here with the less prevalent, but very important, breaking of carbon bonds with sulfur, nitrogen and oxygen taking place in parallel. 

Many books, reviews and treatises have been pubUshed on related subjects [1-7]. Thus the objective of this chapter is the deUneation of the key features of the catalytic surface and the process conditions which enable better control of the reaction pathways for more efficient and environmentally friendly processes and minimal utiHzation of precious natural resources. As it stands today, hundreds of known framework types have been synthesized and scaled-up [8], but only a handful have found significant application in the hydrocarbon processing industries. They are zeolite Y and its many variants, ZSM-5, Mordenite and zeohte Beta. Other very important crystalline materials (including aluminophosphates (ALPOs), 

Zeolites in Industrial Separation and Catalysis. Edited by Sand Kulprathipanja Copyright 2010 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-32505-4 

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Hydrocracking and hydroisomerization are related bond breaking and rearrangement processes which rely on the use of dual function catalysts operating under high hydrogen pressure to achieve their objectives. In fact, they share the same fundamental mechanistic steps and differ mainly in the degree to which some... 

Chapter 16 discusses carbon-carbon bond breaking and rearrangement The chapter attempts to identify the key properties of zeolites which must be tailored... 

In acid-base catalysis,proton addition to or abstraction from reactant molecules (with Bronsted acids or bases), or formation of coordination bonds (with Lewis acids), and subsequent bond breaking and rearrangement are the key reaction processes. Most cases involve ionic reaction intermediates bound to the surface by electrostatic interactions. 

Before considering detector characteristics and some recent developments in chemiluminescence detection, it should be noted that analytical applications of chemiluminescence involve two types of chemiluminescent response. In the first type, the chemiluminescent molecule is used as a detection label and is, therefore, present in limiting concentration relative to the reagents used to initiate the chemiluminescent reaction. The chemical reaction will therefore be pseudo first order. The slowest process in the sequence of events leading to light emission is the reaction itself, e.g., hydrolysis, bond-breaking, and rearrangements. From Eq. 

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