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کاتالیزور کاربردی a: عمومی 2012
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همایش ، رویداد ، ژورنال
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  • ring opening of decalin via hydrogenolysis on ir/- and pt/silica catalysts

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    • تاریخ ارائه: 1392/07/24
    • تاریخ انتشار در تی پی بین: 1392/07/24
    • تعداد بازدید: 1363
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     the catalytic conversion of cis-decalin was studied at a hydrogen pressure of 5.2 mpa and temperatures of 250–410 °c on iridium and platinum supported on non-acidic silica. the absence of catalytically active brønsted acid sites was indicated by both ft-ir spectroscopy with pyridine as a probe and the selectivities in a catalytic test reaction, viz. the hydroconversion of n-octane. on iridium/silica, decalin hydroconversion starts at ca. 250–300 °c, and no skeletal isomerization occurs. the first step is rather hydrogenolytic opening of one six-membered ring to form the direct ring-opening products butylcyclohexane, 1-methyl-2-propylcyclohexane and 1,2-diethylcyclohexane. these show a consecutive hydrogenolysis, either of an endocyclic carbonsingle bondcarbon bond into open-chain decanes or of an exocyclic carbonsingle bondcarbon bond resulting primarily in methane and c9 naphthenes. the latter can undergo a further endocyclic hydrogenolysis leading to open-chain nonanes. all individual c10 and c9 hydrocarbons predicted by this “direct ring-opening mechanism” were identified in the products generated on the iridium/silica catalysts. the carbon-number distributions of the hydrocracked products c9− show a peculiar shape resembling a hammock and could be readily predicted by simulation of the direct ring-opening mechanism. platinum on silica was found to require temperatures around 350–400 °c at which relatively large amounts of tetralin and naphthalene are formed. the most abundant primary products on pt/silica are spiro[4.5]decane and butylcyclohexane which can be readily accounted for by the well known platinum-induced mechanisms described in the literature for smaller model hydrocarbons, namely the bond-shift isomerization mechanism and hydrogenolysis of a secondary-tertiary carbonsingle bondcarbon bond in decalin.

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