Reforming, of petroleum

Supported bimetallic Re—Pt catalysts are important in selective reforming of petroleum. It is believed that sulhding the catalyst before use gives ReS units which act as inert diluents to reduce the size of a local ensemble of platinum atoms. Selectivity for desirable dehydrocyclization and isomerization reactions... 

The remaining two reviews treat active topics in applied chemical kinetics. Wehner provides a unified treatment of the theory of flames, including the role of intermediates and the problems of flammability limits and ignition conditions. Sinfelt discusses the near-simultaneous conduct of successive reactions needed, for instance, in the reforming of petroleum fractions, as produced by intimate mixtures of metallic and acidic catalysts. 

Most multipromoted catalysts have been described for the catalytic reforming of petroleum. For this process it is typical, that several reactions take place simultaneously dehydrogenation of cyclohexanes, dehydroisomerization of alkylcyclopentanes and dehydrocyclization of alkanes. Isomerization, hydrogenolysis, and hydrocracking are also involved in the process. 

The reforming of petroleum fractions boiling between about 90 and 200°C. to high octane gasolines constitutes one of the largest scale industrial catalytic operations of our times. The quantity processed over platinum catalysts exceeds 2 X 10 liters/day. A majority of the reactions involved are polystep hydrocarbon conversions (see refs. 10,11, and the extensive review of the art by Ciapetta et al., 31). 

Interest in carbon deposition cm platinum surfaces has been driven by the fact that this metal and its alloys are used extensively in the reforming of petroleum naphthas. This reaction is carried out over bi-functional catalysts which consist of a single metal (e.g. Pt) or a combination of metals (e.g. Pt/Ir, Pt/Re, Pt/Sn) dispersed on an acidic support such as alumina, on which the acidity is controlled by addition of... 

Derivation (1) Hydrodealkylation of toluene or pyrolysis of gasoline (2) transalkylation of toluene by disproportionation reaction (3) catalytic reforming of petroleum (4) fractional distillation of coal tar. 

Even so, it would be improper to include in such a discussion certain groups of chemicals such as nitrobenzene or aniline, despite the fact that the aromatic hydrocarbons which give rise to them are now substantially obtained by the reforming of petroleum hydrocarbons. However, there is always the possibility that the catalytic processes can give supplies of nearly every aromatic hydrocarbon, and since the latter are easily nitrated there is thereby a means of obtaining in two or three steps the nitro compounds, amines, hydroxylamines, hydrazines, etc., of the whole aromatic field. 

Xylenes. Mixed xylenes are generally obtained by the catalytic reforming of petroleum fractions (see Section 6.2.1.7, above) or by the recovery of the Cg fraction from an aromatic concentrate (pyrolysis gasoline) stream. An increasingly important source of mixed xylenes is from the disproportionation of toluene. The separation of mixed xylenes into para, meta, and ortho isomers can be accomplished by several methods (e.g., fractional crystallization). 

This monograph describes research on bimetallic catalysts conducted at the Exxon Research and Engineering laboratories since the early 1960s. Much of the monograph is concerned with research directed toward the validation and elucidation of the bimetallic cluster concept. Some discussion is devoted also to the technological aspects of these systems, with emphasis on their application for the catalytic reforming of petroleum fractions. 

Bimetallic catalysts have had a major impact in industrial catalysis, notably in the catalytic reforming of petroleum fractions. As background for a discussion of the application of such catalysts in the reforming process, some of the major features of catalytic reforming are reviewed first. 

Research on bimetallic catalysts has had a major impact in the reforming of petroleum naphtha fractions to produce high octane number components for gasolines. During the 1970s, bimetallic catalysts largely replaced traditional... 

The selectivity [e.g., the rate of hydrogenolysis relative to the rate of dehydrogenation (both of which are important reactions in the reforming of petroleum distillates)] may also depend on crystallite size ... 

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. 

These equations show that the hydrogenation process can be likened to the processes of catalytic cracking and reforming of petroleum in which a variety of saturated, unsaturated, aromatic and naphthenic compounds are produced [Macrae, 1966b],... 

Normally intramolecular elimination of alkane from alkyl(hydride) complexes occurs readily and is favoured thermodynamically. There is interest, however, in the possibility of carrying out the reverse reaction, the addition of a C—H bond to an unsaturated transition metal centre. Alkanes are susceptible to electrophilic attack, for example by Lewis or Br nsted acids which convert linear alkanes into their branched isomers via carbonium ion intermediates. Linear and cyclic alkanes can be converted into aromatic hydrocarbons and hydrogen over metal surfaces such as platinum. These reactions are carried out on a large scale industrially in the reforming of petroleum. 

The current raw material base for the production of nylon 66 is benzene, which is derived almost entirely from catalytic cracking and reforming of petroleum. Catalytic reduction of benzene to cyclohexane followed by catalyzed air oxidation gives a... 

Other Processes from catalytic reforming of petroleum and also from fractional distillation of coal tar and oil... 

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