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dc.contributor.authorSayan, S.en_US
dc.contributor.authorDemirel, B.en_US
dc.contributor.authorPaul, J.en_US
dc.date.accessioned2016-02-08T10:37:36Z
dc.date.available2016-02-08T10:37:36Z
dc.date.issued2000en_US
dc.identifier.issn0016-2361
dc.identifier.urihttp://hdl.handle.net/11693/25009
dc.description.abstractHydrocracking of methyldecalin over Pd/REX has been studied with surface sensitive techniques in the critical temperature range 325– 3508C. Results from in situ characterization of adsorbed species, and post-reaction analysis of the catalyst surface by infrared and photoemission spectroscopies, were related to product distributions. The results are discussed in light of quantum chemical calculations of free and catalyst bound intermediates, following ring-opening reactions. Liquid and gaseous products were detected by infrared and UV/Vis spectroscopies. Apparent activation energies of product formation hydrogen consumption, over a broader temperature range, were derived from previous autoclave experiments. An increase in temperature, 325–3508C, results in a shift from preferred cracking products to aromatics, an enhanced level of light hydrocarbon off-gases, and a higher coverage of carbonaceous residues. The increased level of carbonaceous residues is accompanied by a lowered coverage of the reactant, at the surface. The altered product distribution can be characterized by apparent single activation energies, valid from 300 to 4508C. Methane and aromatics show a similar rapid increase with temperature, hydrogen consumption a more timid increase, indicating a reaction limited by diffusion, and cycloalkane production a modest inverse temperature dependence. Fully hydrogenated ring-opening products represent valuable fuel components, but hydrogen deficiency can instead lead to chemisorbed precursors to coke. Our calculations show that cyclohexane, 1,2-diethyl, 3-methyl has a lower heat of formation than the corresponding surface intermediates, but a small enthalpy advantage can easily be countered by entropy effects at higher temperatures. This balance is critical to the formation of preferred products, instead of catalyst deactivation and aromatics. The theoretical results further show that surface intermediates, where the terminating hydrogen is replaced by a C–O bond, have distinct vibrations around 1150 cm21. q2000 Elsevier Science Ltd. All rights reserved.en_US
dc.language.isoEnglishen_US
dc.source.titleFuelen_US
dc.relation.isversionofhttp://dx.doi.org/10.1016/S0016-2361(99)00276-8en_US
dc.subjectAromatic hydrocarbonsen_US
dc.subjectCatalystsen_US
dc.subjectCrude petroleumen_US
dc.subjectEmission spectroscopyen_US
dc.subjectInfrared spectroscopyen_US
dc.subjectPalladiumen_US
dc.subjectPhotoemissionen_US
dc.subjectTemperatureen_US
dc.subjectUltraviolet spectroscopyen_US
dc.subjectZeolitesen_US
dc.subjectMethyldecalinen_US
dc.subjectRare earth exchangeen_US
dc.subjectSurface sensitive measurementen_US
dc.subjectHydrocrackingen_US
dc.titleMethyldecalin hydrocracking over palladium/zeolite-Xen_US
dc.typeArticleen_US
dc.departmentDepartment of Chemistryen_US
dc.citation.spage1395en_US
dc.citation.epage1404en_US
dc.citation.volumeNumber79en_US
dc.citation.issueNumber11en_US
dc.identifier.doi10.1016/S0016-2361(99)00276-8en_US
dc.publisherElsevier Science Ltd, Exeter, United Kingdomen_US


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