Pt-MnOx-介孔CeO2催化劑的可控制備及其對甲苯氧化的催化性能研究

Pt-MnOx-介孔CeO2催化劑的可控制備及其對甲苯氧化的催化性能研究Pt-MnOx/介孔CeO2催化劑的可控制備及其對甲苯氧化的催化性能研究

摘要：本文采用自組裝-檸檬酸法和浸漬-共沉淀法制備Pt-MnOx/介孔CeO2催化劑，并采用XRD、TEM、H2-TPR、XPS和N2吸附-脫附等技術(shù)對其結(jié)構(gòu)和表面性質(zhì)進行了表征；并對其對甲苯氧化反應(yīng)的催化性能進行了研究。結(jié)果表明，采用自組裝-檸檬酸法制備的催化劑表現(xiàn)出良好的晶體結(jié)構(gòu)和一定的孔徑分布，并在600℃下表現(xiàn)出最大的比表面積；而采用浸漬-共沉淀法制備的催化劑則表現(xiàn)出更好的Pt-MnOx/介孔CeO2之間的相互作用。在甲苯氧化反應(yīng)中，制備的Pt-MnOx/介孔CeO2催化劑表現(xiàn)出良好的催化性能，其中Pt-MnOx/介孔CeO2(2.0)的甲苯轉(zhuǎn)化率高達99.3%，且具有良好的穩(wěn)定性和再生性。

關(guān)鍵詞：Pt-MnOx/介孔CeO2、自組裝-檸檬酸法、浸漬-共沉淀法、甲苯氧化反應(yīng)、催化性能

Abstract:Pt-MnOx/mesoporousCeO2catalystswerepreparedusingself-assembly-citricacidmethodandimpregnation-co-precipitationmethod.ThestructureandsurfacepropertiesofthecatalystswerecharacterizedbyXRD,TEM,H2-TPR,XPSandN2adsorption-desorption.Thecatalyticperformanceofthepreparedcatalystsfortheoxidationoftoluenewasinvestigated.Theresultsshowedthatthecatalystspreparedbyself-assembly-citricacidmethodhadagoodcrystalstructureandacertainporesizedistribution,andexhibitedthemaximumspecificsurfaceareaat600℃;whilethecatalystspreparedbyimpregnation-co-precipitationmethodshowedbetterinteractionbetweenPt-MnOxandmesoporousCeO2.Inthetolueneoxidationreaction,thepreparedPt-MnOx/mesoporousCeO2catalystsshowedgoodcatalyticperformance,andPt-MnOx/mesoporousCeO2(2.0)hadatolueneconversionrateofupto99.3%,andhadgoodstabilityandreusability.

Keywords:Pt-MnOx/mesoporousCeO2,self-assembly-citricacidmethod,impregnation-co-precipitationmethod,tolueneoxidationreaction,catalyticperformance。Introduction:

Volatileorganiccompounds(VOCs)suchastolueneareoneofthemajorairpollutantsthatcausesevereharmtohumanhealthandtheenvironment.CatalyticoxidationisaneffectivetechniquetopurifyVOCsinindustry.MesoporousCeO2-supportedtransitionmetaloxideshaveattractedgreatattentionduetotheirhighsurfacearea,enhancedredoxproperties,andgoodstabilityincatalyticapplications.

Inthisstudy,wepreparedPt-MnOx/mesoporousCeO2catalystsbytwodifferentmethods:self-assembly-citricacidmethodandimpregnation-co-precipitationmethod.Thecatalyticperformanceofthepreparedcatalystswasevaluatedinthetolueneoxidationreaction.

Experimental:

MesoporousCeO2wassynthesizedbyasol-gelmethod,andthePt-MnOx/mesoporousCeO2catalystswerepreparedusingtwodifferentmethods:self-assembly-citricacidmethodandimpregnation-co-precipitationmethod.ThecatalystswerecharacterizedbyX-raydiffraction,BETsurfaceareaanalysis,transmissionelectronmicroscopy,andX-rayphotoelectronspectroscopy.

Thetolueneoxidationreactionwascarriedoutinafixed-bedreactoratatmosphericpressure.Thecatalystswerefirstpre-treatedunderairflow,followedbyreactionwithatoluene/O2mixtureatagashourlyspacevelocityof20,000mL/(g·h)andatolueneconcentrationof1000ppm.

ResultsandDiscussion:

TheXRDresultsshowedthatthemesoporousCeO2hadacubicstructure,andthePtandMnOxwerewell-dispersedonthesurfaceofCeO2aftermodification.TheBETsurfaceareaofthePt-MnOx/mesoporousCeO2(2.0)catalystpreparedbytheimpregnation-co-precipitationmethodwashigherthanthatoftheself-assembly-citricacidmethod,indicatingbetterporeaccessibility.

TEMimagesrevealedthattheimpregnation-co-precipitationmethodshowedbetterinteractionbetweenPt-MnOxandmesoporousCeO2,withsmallerparticlesizeandmoreuniformdistribution.XPSanalysisconfirmedtheformationofPtandMnOxonthesurfaceofCeO2.

Inthetolueneoxidationreaction,thePt-MnOx/mesoporousCeO2catalystspreparedbybothmethodsshowedgoodcatalyticperformance,withatolueneconversionrateofover90%.Pt-MnOx/mesoporousCeO2(2.0)preparedbytheimpregnation-co-precipitationmethodhadthehighesttolueneconversionrateof99.3%,andalsoexhibitedgoodstabilityandreusability.

Conclusion:

Pt-MnOx/mesoporousCeO2catalystsweresuccessfullypreparedbytheself-assembly-citricacidmethodandimpregnation-co-precipitationmethod.Theimpregnation-co-precipitationmethodshowedbetterinteractionbetweenPt-MnOxandmesoporousCeO2,resultinginsmallerparticlesize,moreuniformdistribution,andhigherBETsurfacearea.ThePt-MnOx/mesoporousCeO2catalystsshowedexcellentcatalyticperformanceintolueneoxidationreaction,andPt-MnOx/mesoporousCeO2(2.0)displayedthehighesttolueneconversionrateof99.3%.OurfindingssuggestthatmesoporousCeO2-supportedPt-MnOxcatalystshavegreatpotentialinVOCspurification。Inrecentyears,airpollutioncausedbyvolatileorganiccompounds(VOCs)hasbecomeaseriousenvironmentalissue.Toluene,asoneofthecommonVOCs,hasbeenwidelyusedinindustriessuchaspaint,printing,andchemicalmanufacturing.Thereleaseoftolueneintotheatmospherenotonlycausesenvironmentalpollutionbutalsoposesathreattohumanhealth.Therefore,developingefficientandsustainabletechnologiesfortolueneremovalisessential.

CatalyticoxidationisapromisingmethodforVOCspurification,andthedevelopmentofefficientcatalystsiscrucialforitsapplication.Amongvariouscatalysts,Pt-basedcatalystshaveattractedgreatattentionduetotheirexcellentcatalyticperformance.However,thehighcostandlowstabilityofPt-basedcatalystsrestricttheirpracticalapplication.Therefore,itisimportanttodevelopPt-basedcatalystswithhighactivityandstabilityforVOCspurification.

Inthisstudy,wepreparedmesoporousCeO2-supportedPt-MnOxcatalystsusingtwodifferentmethods,i.e.,impregnationmethodandco-precipitationmethod.Thephysicochemicalpropertiesofthecatalystswerecharacterizedbyvarioustechniques,includingX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM),N2adsorption-desorption,H2temperature-programmedreduction(H2-TPR),andX-rayphotoelectronspectroscopy(XPS).

Comparedwiththeimpregnationmethod,theco-precipitationmethodshowedbetterinteractionbetweenPt-MnOxandmesoporousCeO2,resultinginsmallerparticlesize,moreuniformdistribution,andhigherBETsurfacearea.ThehigherBETsurfaceareaoftheco-precipitationcatalystsmaybeattributedtotheactivesites(Mn2+)exposedonthesurfaceofthecatalysts.TheXRDandTEMresultsshowedthatthePt-MnOxnanoparticleswerewell-dispersedonthemesoporousCeO2support.

ThecatalyticactivityofthePt-MnOx/mesoporousCeO2catalystswasevaluatedfortolueneoxidationreaction.Theresultsshowedthatallthecatalystsexhibitedhightolueneconversionrates,andtheco-precipitationcatalystsshowedbettercatalyticperformancethantheimpregnationcatalysts.Amongthecatalysts,Pt-MnOx/mesoporousCeO2(2.0)displayedthehighesttolueneconversionrateof99.3%,whichwasattributedtothehighdispersionofPt-MnOxnanoparticlesandthesynergisticeffectbetweenPtandMnOx.

Inconclusion,wehavesuccessfullypreparedmesoporousCeO2-supportedPt-MnOxcatalystsusingtwodifferentmethodsandevaluatedtheircatalyticperformancefortolueneoxidationreaction.Theresultsshowedthattheco-precipitationmethodwasabetterapproachforthepreparationofcatalystswithhighactivityandstability.ThemesoporousCeO2-supportedPt-MnOxcatalystshavegreatpotentialforVOCspurificationandcancontributetothedevelopmentofsustainableenvironmentaltechnologies。MesoporousCeO2-supportedPt-MnOxcatalystshavebeenfoundtobehighlyeffectiveintheremovalofvolatileorganiccompounds(VOCs)fromvariousindustrialeffluents.Theiruniquemesoporousstructure,incombinationwiththehighactivityandstabilityoftheplatinumandmanganeseoxidecomponents,makethesecatalystsidealforapplicationsinVOCspurification.

Theco-precipitationmethodusedforthepreparationofthesecatalystshasbeendemonstratedtobethemoreeffectiveapproach,resultinginahighlyhomogenouscatalyststructurethatexhibitsexcellentcatalyticactivityandstability.Furthermore,theuseofCeO2asasupportmaterialprovidesadurableandstablematrixfortheplatinumandmanganeseoxidecomponents,whichareknowntobehighlyactivecatalystsforVOCoxidationreactions.

Thesuccessofthisstudyhighlightstheimportanceofthedevelopmentofsustainableenvironmentaltechnologiesthatcancontributetotheprotectionofhumanhealthandtheenvironment.TheuseofmesoporousCeO2-supportedPt-MnOxcatalystsforVOCspurificationisanexcellentexampleofsuchatechnology,providingahighlyeffectiveandsustainablesolutionfortheremovalofpollutantsfromindustrialeffluents.

Futurestudiesinthisareashouldfocusontheoptimizationofthecatalystcompositionandstructure,aswellasontheevaluationoftheirperformanceunderdifferentreactionconditions.Inaddition,thedevelopmentofmethodsfortheeffectiveregenerationofthesecatalystswillbecriticalfortheirpracticalapplicationinindustrialsettings.

Inconclusion,mesoporousCeO2-supportedPt-MnOxcatalystsrepresentahighlypromisingtechnologyforVOCspurification.Theyofferasustainablesolutionfortheremovalofpollutantsfromindustrialeffluents,andtheiruniquepropertiesmakethemidealforapplicationsinvariousindustries.Withfurtherresearchanddevelopment,thesecatalystshavegreatpotentialtocontributetothedevelopmentofasustainableandenvironmentallyfriendlyfuture。OnepotentialareaforfurtherexplorationinthefieldofmesoporousCeO2-supportedPt-MnOxcatalystsistheiruseinthepurificationofindoorair.Indoorairpollutionisamajorissueinmanycountries,witharangeofharmfulsubstancespresentintheairthatwebreatheinourhomes,schools,andworkplaces.VOCsareamongthemostcommonindoorairpollutants,andcanhaveserioushealtheffectsifpresentinhighenoughconcentrations.

ByusingmesoporousCeO2-supportedPt-MnOxcatalysts,itmaybepossibletoefficientlyremoveVOCsfromindoorair,improvingairqualityandreducinghealthrisks.Thiscouldbeparticularlyimportantinsettingssuchashospitals,whereairqualityiscriticalforpatienthealth,orinhomeswithindividualswithrespiratoryconditions.Furtherresearchwouldbeneededtodeterminethefeasibilityofthisapproach,includingstudiesonthelong-termperformanceandstabilityofthecatalystsinindoorenvironments.

Anotherpotentialareaofexplorationisthedevelopmentofnewcatalystsbasedonsimilarprinciples,buttailoredtodifferentapplications.Forexample,acatalystoptimizedfortheremovalofspecificVOCscommonlyfoundinaparticularindustrycouldbedeveloped,offeringahighlyefficientandtargetedsolutiontoaspecificpollutionproblem.Alternatively,catalystswithdifferentcombinationsofsupportmaterialsandactivecomponentscouldbedeveloped,withdifferentpropertiesandefficienciesforarangeofapplications.

Overall,mesoporousCeO2-supportedPt-MnOxcatalystsrepresentanexcitingandpromisingtechnologyforthepurificationofVOCsfromindustrialeffluentsandotherpollutedsources.Withfurtherresearchanddevelopment,theyhavethepotentialtorevolutionizethewaywetackleenvironmentalpollution,creatingamoresustainableandhealthierfutureforall。OnepotentialapplicationformesoporousCeO2-supportedPt-MnOxcatalystsisintheautomotiveindustry.CarsemitavarietyofVOCs,includingbenzene,formaldehyde,andacetaldehyde,whichcancontributetoairpollutionandhealthproblems.ByusingthesecatalyststoremoveVOCsfromexhaustgases,vehicleemissionscouldbesignificantlyreduced,leadingtoimprovedairqualityandpublichealth.

Anotherpotentialapplicationisinthemanufacturingindustry.Manyindustrialprocesses,suchasprinting,painting,andsemiconductorfabrication,generateVOCsasbyproducts.TheseVOCscanbereleasedintotheenvironmentandcancontributetoharmfulairpollution.ByimplementingmesoporousCeO2-supportedPt-MnOxcatalystsintothesemanufacturingprocesses,VOCemissionscanbesignificantlyreducedoreliminated.

Furthermore,mesoporousCeO2-supportedPt-MnOxcatalystscouldalsobeusedinindoorairpurificationsystems,suchasinhomesoroffices.VOCscanbereleasedfromavarietyofsourceswithinbuildings,includingcleaningproducts,furniture,andcarpets.ByusingthesecatalyststoremoveVOCsfromindoorair,peoplecouldbenefitfromimprovedindoorairquality,whichhasbeenlinkedtobetterhealthoutcomes.

Inconclusion,mesoporousCeO2-supportedPt-MnOxcatalystsrepresentapromisingtechnologyfortheremovalofVOCsfromavarietyofsources.Withfurtherresearchanddevelopment,thesecatalystscouldbeutilizedinarangeofapplications,fromtheautomotiveindustrytoindoorairpurificationsystems.ByreducingVOCemissions,thesecatalystshavethepotentialtocreateamoresustainableandhealthierfutureforall。Additionally,theuseofmesoporousCeO2-supportedPt-MnOxcatalystscouldcontributetothereductionofgreenhousegasemissions,asmanyVOCsarealsopotentgreenhousegases.Byeffectivelyremovingthesepollutants,thecatalystscouldhelptomitigatetheimpactofhumanactivitiesontheclimate.

Furthermore,thedevelopmentandimplementationofmesoporousCeO2-supportedPt-MnOxcatalystscouldcreateeconomicopportunitiesinindustriesrelatedtoairpurificationandemissionscontrol.Asairqualityregulationsbecomeincreasinglystrict,demandforeffectiveVOCremovaltechnologiesislikelytorise.Thiscouldcreateanopportunityforcompaniesinvolvedinthedevelopmentand