THE MECHANISM OF THE CATALYTIC OXIDATION OF SOME O

PLEASESCROLLDOWNFORARTICLEThisarticlewasdownloadedby:On:24January2011Accessdetails:AccessDetails:FreeAccessPublisherTaylor&FrancisInformaLtdRegisteredinEnglandandWalesRegisteredNumber:1072954Registeredoffice:MortimerHouse,37-41MortimerStreet,LondonW1T3JH,UKCatalysisReviewsPublicationdetails,includinginstructionsforauthorsandsubscriptioninformation:~content=t713597232THEMECHANISMOFTHECATALYTICOXIDATIONOFSOMEORGANICMOLECULESW.M.H.SachtleraaKoninklijke/Shell-Laboratorium,(ShellResearchN.V.),Amsterdam,TheNetherlandsTocitethisArticleSachtler,W.M.H.(1971)'THEMECHANISMOFTHECATALYTICOXIDATIONOFSOMEORGANICMOLECULES',CatalysisReviews,4:1,27—52TolinktothisArticle:DOI:10.1080/01614947108075484URL::*W.M.H.SACHTLERKoninklijkelShell-Laboratorium,Amsterdam(ShellResearchN.V.)TheNetherlandsI.INTRODUCTION.............................27II.CHEMISORPTIONOFUNSATURATEDHYDROCARBONSBYANOXIDESURFACE...........29111.ADSORBEDFORMSOFOXYGENONSILVER..........35IV.ADSORBEDFORMSOFOXYGENONOXIDES..........42V.CONCLUSION...............................49References.................................49I.INTRODUCTIONTherevolutioninindustrialorganicchemistryduringthelasttwodecadesischaracterizedbytwomarkedchanges:theuseofdifferentbasematerialsandthemanufactureofdifferentproducts.Coaltar,thetraditionalbasematerial,hasbeenreplacedbypetroleumfrac-tions,i.e.,industrialorganicchemistryhasbeenlargelytransformedintopetrochemistry.Amongtheproductspolymersarepredominant.Anecessaryconditionforreplacingthebasematerialwasthatmanlearnedtochangethechemicalstructureofhydrocarbonsbynotmerelyburningthem,butusingthemforthesynthesisofnewmole-cules.Thedecisivefactorthatrenderedthispossiblewashetero-geneouscatalysis.In1783Priestleydiscoveredthatwhenalcoholvaporwaspassedthroughtheheatedstemofaceramictobaccopipe,itdecomposedintoetheneandwater.In1795vanTroostwijk,Bondt,andLauwren-*Thispaperwaspresentedatthesymposiumon“OxidationinOrganicChemistry,”UniversityofManchester,July8and9,1969.27DownloadedAt:23:5424January201128W.M.H.SACHTLERbourghinHollandobservedthatclaymaterialwasessentialforthiscatalyticdecomposition:onlywhenclayfragmentswereinserteddiddecompositionoccurinheatedglasspipes.Itwasnotuntil1935thatHoudrysucceededinintroducingthecatalyticcrackingprocessintoindustrywithsilica-aluminaasthecatalyst.Thusthewaywasopenedforpreparingnotonlyhigh-qualitygasoline,butalsohugeamountsoflow-molecular-weightolefinicmonomersandaromaticsfromcrudeoil.Someoftheseolefinsarepolymerizedto,e.g.,isotacticpolypropylene,thusundergoingasecondcatalytictreatment.Mostoftheselow-molecular-weightolefinsandaromatics,however,havetobesubjectedtooneormorepartialoxidationsbeforetheybecometruepetrochemicals.Etheneisconvertedintoetheneoxide;propeneintoacrolein,acrylicacid,oracrylonitrile;buteneintobutadieneormethacrolein;benzeneintomaleicanhydride;naphthaleneintophthalicanhydride,tomentionjustafewexamples.Inallthesereactionsoxidationmustbeselective,becausetheproductspre-ferredbythermodynamics,namelyCO,,CO,andH,O,areobviouslynotdesired.Forthisselectiveoxidationacatalystisaprerequisite,becauseinanoncatalyzedreactionatlowtemperaturestherateisfartoolow,whereasathighertemperatures,whenthereactionratebecomesappreciable,theselectivityisnearlyzero.Variouspublications[l,21describeexperimentalresultsofcatalyticoxidationsandspeculateonthemechanismsoftheseim-portantprocesses.Evenfortheinsideritisdifficulttokeeptabsonthespateofpublicationsinthisfield.Thepurposeofthispaperis,therefore,toreviewthepublishedmaterialfromtheangleofthere-actionmechanismandtoseewhatgenerallawscanbederivedfromthedataavailableatpresent.Withthisaiminmindweshallconsideronlythoseoxidationswheretheelementoxygenisinvolvedasareactionpartner.Inpar-ticular,weshallmakeuseofdatacollectedwithfourmodelre-actions,viz.:C,H,+30,-C,H,Oetheneoxide(1)C3H6+O2Bi,O,*xMoOFC3H,0+H,Oacrolein(2)C,H8+*O,----tC,H,+H,Obutadiene(3)Bi,O,*xMoO,C,H,CHO+h0,C,H,COOHbenzoicacid(4)InallthesereactionsitisclearthatboththehydrocarbonandtheoxygenmoleculemustinteractchemicallywithatomsofthecatalystDownloadedAt:23:5424January2011CATALYTICOXIDATIONOFSOMEORGANICMOLECULES29surface.Theseinteractionshavebeensubjectofintensiveexperi-mentalandtheoretica