%0 Journal Article
%T ReactionMechanismandDeactivationModesofHeterogeneousCatalyticSystems
%J ´ß»¯Ñ§±¨
%P 387-404
%D 2011
%R 10.1016/S1872-2067(10)60181-7
%X £¿Solvingtheproblemofcatalystdeactivationisessentialinprocessdesign.Todothis,variousaspectsofthekineticsofprocesseswithcatalystdeactivation,andtheirdifferentmechanisms,arediscussed.Catalystdeactivationoftencannotbeavoided,butmoreknowledgeonitsmechanismcanhelptofindkineticmeanstoreduceitsharmfulconsequences.Whendeactivationiscausedbycoke,thegenerationofcokeprecursorsisthedeterminingstepinthedeactivationkinetics.Differenttypesofdeactivationweredistinguishedthatleadtodifferentevolutionoftheprocess.Thephenomenonofnon-uniformcokingcanbelinkedtocatalystsurfacenon-uniformity.Fortheclassofcatalystswithmorethanonetypeofactivesites,anexplanationwassuggestedfortheobservedtrendsinthedeactivationmodes.Forcatalyticprocessesusingcatalystparticlesofindustrialsize,theinfluenceofintraparticlediffusionresistanceisimportant.Theanalysisshowedthatforanumberofprocesses,thedecreaseofthereactionrateduetodeactivationislessunderdiffusioncontrol.Forcertainreactionmechanisms,thereexistoperationconditionswheretherateoftheprocessunderdiffusioncontrolexceedstherateinthekineticcontrolregime.Asignificantproblemisthechangeofselectivityinthecourseofcatalystdeactivation.Theselectivitymayeitherdecreaseorincrease,anddependsonthereactionmechanismduringdeactivation.Thechangesarelargerwhenthereisnodiffusionresistance.Theintentionalpoisoningofcatalystsanditsinfluenceoncatalystactivityandselectivityfortheprocessofethyleneoxideproductionwasdiscussed.
%K catalystactivity
%K catalystselectivity
%K catalystdeactivation
%K activesite
%K diffusionregime
%U http://www.chxb.cn/CN/abstract/abstract20332.shtml