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1、TheFirecat®catalyticcombustorWhatiscatalysis?Catalysisisaprocessinwhichtherateofachemicalreactionischangedbyasubstancecalledacatalyst.Unlikeotherreagentsthatparticipateinthechemicalreaction,acatalystisnotconsumedbythereactionitself.Althoughcatalystsarenotc
2、onsumedbythereactionitself,theymaybeinhibited,deactivatedordestroyedbysecondaryprocesses.Inheterogeneouscatalysis,typicalsecondaryprocessesincludecokingwherethecatalystbecomescoveredbypolymericsideproducts.Catalystsdonotchangetheextentofareaction:theyhaven
3、oeffectonthechemicalequilibriumofareactionbecausetherateofboththeforwardandthereversereactionarebothaffected(seealsothermodynamics).Thefactthatacatalystdoesnotchangetheequilibriumisaconsequenceofthesecondlawofthermodynamics.Supposetherewassuchacatalystthat
4、shiftedequilibrium.Introducingthecatalysttothesystemwouldresultinreactiontomovetothenewequilibrium,producingenergy.ProductionofenergyisanecessaryresultsincereactionsarespontaneousifandonlyifGibbsfreeenergyisproduced,andifthereisnoenergybarrier,thereisnonee
5、dforacatalyst.Then,removingthecatalystwouldalsoresultinreaction,producingenergy;i.e.theadditionanditsreverseprocess,removal,wouldbothproduceenergy.Thus,acatalystthatcouldchangetheequilibriumwouldbeaperpetualmotionmachine,acontradictiontothelawsofthermodyna
6、mics.(http://en.wikipedia.org/wiki/Catalysis)Thoughcatalystsareusedincountlessapplicationsinchemistry,foodprocessing,painting,coating,laminating,engineemissioncontrols...;we’reinterestedinthesmallgroupofso-called“OxidationCatalysts”only.Oxidationcatalysisw
7、orksasfollows:O2inafirststepdissociatesto2Owhichisthenformingunstablechemicalcompoundswithnoblemetalparticlesincorporatedinawash-coatlayer.ThesepreciousmetalsarePalladium(Pd),Platinum(Pt),andRhodium(Rh).Bythiswayresidualoxygenthatwouldotherwisejustleavethr
8、uchimneyisheldbackandthusforminganenvironmentwith“extraoxygen”;hot,highlyreactive,“free”oxygenradicals.SincebondingforcesbetweenOandnoblemetalsareverylow(whichisinfactthereasonwhythesemetalsare“noble”),Ocanea
