Naphtha reforming, catalytic chemistry

Dehydrocyclisation of alkanes to aromatic compounds is one of the basic reactions of naphtha reforming, which is one of the most important industrial catalytic processes. IThe nature of the ring closure step is one of the main questions of understanding the chemistry of dehydrocyclisation. Sharan reviewed earlier work on tracer studies of this reaction.[ 1 An excellent discussion on the development of ideas and the role of [ C] isotope in elucidating reaction pathways has been published by Davis.Two basic ideas have competed in Scheme 2. One assumed stepwise dehydrogenation of open-chain alkanes then cyclisation as one of... 

But how ubiquitous actually are alkalis in the promotion of reactions catalyzed at metal surfaces An examination of recent authoritative sources [6,7] shows that the majority of medium-to large-scale processes do not employ alkali promoters, even when one includes nonmetallic (i.e., metal oxide) catalysts. In a number of cases (e.g., steam reforming of naphtha) it seems clear that the role of alkali is simply to reduce the acidity of the oxide support. There are famous cases, of course, where the presence of alkali species on the catalytically active metal surface is critically important to the chemistry. Notable are ethene epoxidation (Ag-Cs), ammonia synthesis (Fe-K), acetoxylation of ethene to vinyl acetate (Pd, Pd/Au-K), and Fischer-Tropsch synthesis (Fe, Co, Ru-K). The first three are major industrial... 

Dehydrogenation is a key reaction in the production of commodity chemicals such as butadiene, styrene and formaldehyde and in the catalytic reforming of petroleum naphtha [1-3], In the fine chemical industry, however, dehydrogenation is used less than the numerous hydrogenation reactions which are available. Dehydrogenation is usually an endothermic reaction which requires high temperatures. For such conditions the chemical stability of many fine chemicals is often insufficient. Most of the dehydrogenation reactions used in fine chemistry yield aromatic or heteroaromatic compounds and aldehydes or ketones. 

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