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Ni系水蒸气转化催化剂上积炭和消炭的机理探讨.docx

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Ni系水蒸气转化催化剂上积炭和消炭的机理探讨 Title:MechanismsofCokingandDecokingonNi-BasedCatalystsforSteamReformingofHydrocarbons:ADiscussion Abstract: Cokinganddecokingarecrucialphenomenaincatalyticprocesses,determiningtheperformanceandsustainabilityofcatalysts.Inthispaper,weexplorethemechanismsofcokinganddecokingonNi-basedcatalystsforsteamreformingofhydrocarbons.Understandingtheseprocessesisessentialforoptimizingcatalystdesignandenhancingoverallefficiency. 1.Introduction Thesteamreformingofhydrocarbons,suchasnaturalgasormethane,isakeyprocessintheproductionofhydrogenasacleanenergysource.However,thecatalyticperformanceofNi-basedcatalystsisoftenlimitedbytheformationofcarbondeposits(coking)onthecatalystsurface.Cokingleadstoadeclineincatalyticactivity,selectivity,andstability,thusnecessitatingperiodicregenerationorreplacementofthecatalyst.Therefore,understandingthemechanismsbehindcokinganddevelopingeffectivedecokingtechniquesiscrucialforsustainablecatalyticprocesses. 2.CokingMechanisms Cokingoccursthroughacomplexsequenceofreactionsinvolvingtheadsorption,decomposition,andpolymerizationofhydrocarbonsonthecatalystsurface.Theprecisereactionstepsandkeyintermediatesmayvarydependingonthespecificreactantsandreactionconditions. 2.1AdsorptionofHydrocarbons Hydrocarbonmolecules,suchasmethane,adsorbontothecatalystsurfacethroughweakvanderWaalsforces.Thisleadstotheformationofcarbonaceousspecies,whichcanbeeitherlinearorcyclicstructures. 2.2DecompositionofHydrocarbons Heatingtheadsorbedhydrocarbonsinitiatesthedecompositionprocess,resultinginthereleaseofhydrogenandtheformationofsurfacecarbon.Thissurfacecarboncanbepresentinvariousforms,includingfilamentouscarbonoramorphouscarbon. 2.3PolymerizationofCarbonSpecies Thesurfacecarbonspeciesfurtherundergopolymerizationreactions,leadingtotheformationoflargercarbondeposits.Thesedepositscanobstructactivesitesonthecatalystsurface,reducingthecatalyticactivityandselectivity. 3.FactorsInfluencingCoking SeveralkeyfactorsinfluencethecokingpropensityofNi-basedcatalysts: 3.