Naphthene hydrocarbon dehydrogenation

Wanae and Walters [69] studied the thermal degradation of cyclopentane in a static system at 438-548 °C and under pressure of 38-244mmHg. It is shown that under these conditions the cyclopentane conversion degree was below 25%. There are some other works [70, 71] devoted to cyclopentane dehydrogenation here, however, the cyclopentadiene yield does not exceed 3-11%. 

Studying cyclopentane pyrolysis processes, Frey [72] has found that in a hollow reactor about 5.4% of olefins and diolefms are formed, among which only 2.7% are formed by cyclopentadiene and 66.5% of cyclopentane remain unconverted. Thermal degradation of cyclopentane was thoroughly studied by Japanese scientists [73]. 

As observed from these investigations, the initial material velocity variation from 0.05 to 0.52 ml/(ml h) at 450 °C and 500 °C does not noticeably affect cyclopentadiene yield. At higher temperatures (550 °C and 600 °C) the reaction rate significantly increased within the range of the volume rates mentioned and a higher yield of the target product was reached. 

However, the reaction rate sharply increases with temperature (from 450 °C to 600 °C). For example, for the volume rate of 0.08 ml/(mlh) and the component ratio C5H8 20% H202 = 1 3, 

Conjugated Reactions of Oxidation with Hydrogen Peroxide in the Gas Phase 

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The ability of a catalyst to promote isomerization plays two roles in reforming it increases the amount of branched chain paraffins in the product and it converts naphthene hydrocarbons with cyclopentane rings into cyclohexane ring naphthenes which are necessary for the formation of aromatics by dehydrogenation. 

Once the paraffin and naphthenic hydrocarbons have been converted into reactive unsaturated hydrocarbons, many chemical reactions or processes are possible. Dehydrogenation may occur during decomposition [see Eqs. (19-9) to (19-12) and (19-15)]. In a general processing scheme dehydrogenation is usually coupled with or followed by other processes such as polymerization or alkylation. Reactions that have been termed cycUzaiion or aromatization may also be dehydrogenation reactions and may also involve decomposition, as indicated here ... 

The product coming out of the reactor consists of excess hydrogen and a reformate rich in aromatics. Typically the dehydrogenation of naphthenes approaches 100%. From 0% to 70% of the paraffins are dehydrocyclized. The liquid product from the separator goes to a stabilizer where light hydrocarbons are removed and sent to a debutanizer. The debutanized platformate is then sent to a splitter where Cg and C9 aromatics are removed. The platformate splitter overhead, consisting of benzene, toluene, and nonaromatics, is then solvent extracted (46). 

Aromatization the conversion of nonaromatic hydrocarbons to aromatic hydrocarbons by (1) rearrangement of aliphatic (noncyclic) hydrocarbons (q.v.) into aromatic ring structures and (2) dehydrogenation of alicyclic hydrocarbons (naphthenes). 

Catalytic Reforming A catalytic reaction of heavy naphtha(1) used to produce high-octane gasoline. The byproducts are hydrogen and light hydrocarbons the primary reaction is dehydrogenation of naphthenes to produce aromatics. Some reshaping of paraffins to produce aromatics and some isomerization of paraffins to produce isoparaffins also occur. 

On the other hand, the above may also mean that the initial thermal dehydrogenation of naphthenic compounds in FCC feed is a step which determines the quantity of hydrocarbons which can be converted to aromatics by hydrogen transfer. 

At higher cracking temperature other reactions, i.e. cyclization and dehydrogenation of naphthenes and hydrocarbon pyrolysis with production of benzene and ethylene, butadiene and hydrogen are also possible. 

Supported chromia catalysts have a wide range of applications such as hydrogenation and dehydrogenation reactions of hydrocarbons, the dehydrocyclization of paraffins, dehydroisomerization of paraffins, olefins, and naphthenes, and the polymerization of olefins [1-3]. In order to improve the activity and selectivity, characterization of some critical parameters for both fresh and spent catalysts is necessary. 

In a general scheme for the analysis of a complex mixture of hydrocarbons. Rowan envisaged carrying out the dehydrogenation of a mixture of isoalkanes and naphthenes with a view to selectively determining the content of cyclohexane hydrocarbons from the zones of the aromatic hydrocarbons formed, and also hydrogenation at room temperature for the selective conversion of olefins into the conesponding alkanes. 

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