nanoplate-aggregate co3o4 microspheres for toluene combustion

ChineseJournalofCatalysis35(2014)1475–1481

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Article

Nanoplate‐aggregateCo3O4microspheresfortoluenecombustion

FangWang,HongxingDai*,JiguangDeng,ShaohuaXie,HuanggenYang,WenHanKeyLaboratoryofBeijingonRegionalAirPollutionControlandLaboratoryofCatalysisChemistryandNanoscience,DepartmentofChemistryand ChemicalEngineering,CollegeofEnvironmentalandEnergyEngineering,BeijingUniversityofTechnology,Beijing100124,China

A R T I C L E I N F O

A B S T R A C T

Articlehistory:Received28January2014Accepted3March2014Published20September2014

Nanoplate‐aggregatemicrospherical Co3O4 was prepared by an ethylenediamine‐assisted hydro‐thermal route and characterized bymeans of numerous techniques. Their catalytic activities fortoluenecombustionwereevaluated.TheCo3O4 sampleobtainedusing1.0mlofethylenediamineandahydrothermaltreatmentat140°Cfor12hhadananoplate‐aggregatemicrosphericalmor‐phology.ThismicrosphericalCo3O4samplewithasurfaceareaof66m2g−1hadahigheradsorbedoxygen concentration and better low‐temperature reducibility than bulk Co3O4. Over the Co3O4

microspheresample,thetemperaturesrequiredfor50%and90%tolueneconversionswere230and254°C,respectively,ataspacevelocityof20000mlg−1h−1.ThegoodcatalyticperformanceoftheCo3O4microspheresamplewasrelatedtoitslargesurfacearea,highoxygenadspeciesconcen‐tration,andgoodlow‐temperaturereducibility.

©2014,DalianInstituteofChemicalPhysics,ChineseAcademyofSciences.PublishedbyElsevierB.V.Allrightsreserved.

Keywords:CobaltoxidemicrosphereNanoplatemorphologySurfactant‐assistedhydrothermal synthesisToluenecombustion

1. Introduction

Most volatile organic compounds (VOCs) emitted from in‐dustrial and transportation activities areharmful to the envi‐ronment and human health. Catalytic oxidation is one of themosteffectivewaystoremoveVOCs,andtransitionmetalox‐idesarethemostcommonlyusedcatalysts.Co3O4isaversatiletransitionmetal oxide and shows good catalytic performancefor theoxidationofVOCsdue to its excellent reducibility andplentifuloxygenvacancies[1–3].Thephysicochemicalproper‐tiesofCo3O4stronglydependon itsmorphologyandexposedcrystal faces[4–6]. In thepastyears,a largenumberofCo3O4samples with different morphologies (nanowires [7,8], nano‐rods [4,9,10], nanocubes [5,11,12], and nanospheres [13,14])havebeen fabricated, and someof themwereapplied for the

oxidation of VOCs. For instance, Co3O4 nanoparticles showedgood activity in catalyzingVOCoxidation [15]. Xue et al. [16]observedasignificanteffectofCo3O4morphologyoncatalyticactivityofAu/Co3O4forethyleneoxidation.

Previously,ourgrouphasusedsilica(SBA‐16orKIT‐6)‐andpolymethyl methacralate‐tempalting, hydrothermal, and mi‐croemulsion methods to make ordered mesoporous Co3O4[17,18],sphericalCo3O4[19],andporousCo3O4nanowiresandnanorods [2], and we found that they performedwell in thecombustionof VOCs. To thebest of our knowledge, however,there have been no reports on catalytic oxidation of tolueneover nanoplate‐aggregatemicrospherical Co3O4. In this work,we report the ethylenediamine‐assisted hydrothermal prepa‐rationof Co3O4microspheres and their catalytic performancefortoluenecombustion.

*Correspondingauthor.Tel:+86‐10‐67396118;Fax:+86‐10‐67391983;E‐mail:[email protected] ThisworkwassupportedbytheNationalNaturalScienceFoundationofChina(21377008),2013EducationandTeachingPostgraduateStudentsEducation2011BeijingMunicipalityExcellentPh.D.ThesisSupervisor(20111000501),2013EducationandTeachingPostgraduateStudentsCulti‐vationNationalExcellentPh.D.ThesisSupervisorandCultivationBaseConstruction(005000542513551),andtheFoundationontheCreativeRe‐searchTeamConstructionPromotionProjectofBeijingMunicipalInstitutions.DOI:10.1016/S1872‐2067(14)60072‐3|http://www.sciencedirect.com/science/journal/18722067|Chin.J.Catal.,Vol.35,No.9,September2014

1476 FangWangetal./ChineseJournalofCatalysis35(2014)1475–1481

2. Experimental

2.1. Catalystpreparation

Thenanoplate‐aggregatemicrosphericalCo3O4samplewasprepared using the ethylenediamine‐assisted hydrothermalmethod.Co(NO3)26H2O(2.91g)wasdissolvedin30mldeion‐ized water, and 9 ml NH3H2O aqueous solution (28 wt%NH3H2O:H2O = 1:3, v/v) was then added dropwise to theCo(NO3)2aqueous solution.After stirring for0.5h,0.5,1.0or2.0mlethylenediaminewasaddedunderstirringfor0.5h.Themixed solutionwas transferred to a50‐mlTeflon‐lined stain‐lesssteelautoclave,whichwassealedandheatedat120,140,160,or200°Cfor12h.Aftertheautoclavewascooledtoroomtemperature (RT), the resulting precipitate was filtered out,washedwithdeionizedwaterandabsoluteethanolthreetimes,driedinanovenat60°Cfor24h,andgrounduniformly.Final‐ly, thepowderwas calcined inairusing a rampof1°Cmin−1fromRTto500°Candmaintainedatthistemperaturefor4h,thusgeneratingtheCo3O4samples.TheCo3O4sampleobtainedwith1.0mlethylenediamineinthehydrothermaltreatmentat140°Cfor12hwasdenotedasCo3O4microsphere.TheCo3O4samplesobtainedwith0,0.5,and2.0mlethylenediamineinthehydrothermal treatment at 140 °C for 12 hwere denoted asCo3O4‐1,Co3O4‐2,andCo3O4‐3,respectively.TheCo3O4samplesobtained with 1.0 ml ethylenediamine in the hydrothermaltreatment at 120, 160, and 200 °C for 12 hwere denoted asCo3O4‐4,Co3O4‐5,andCo3O4‐6,respectively.Forcomparison,abulk Co3O4 (Co3O4‐bulk) sample was prepared by thermallydecomposingCo(NO3)2inairat600°Cfor3h.Allofthechemi‐cals (AR) were purchased from Beijing Chemical ReagentCompanyandusedwithoutfurtherpurification.

2.2. Catalystcharacterization

X‐ray diffraction (XRD) patterns of the samples were rec‐ordedonaBrukerD8AdvancediffractometerwithCuKαradia‐tionandnickel filter(=0.15406nm).Thescanningelectronmicroscopic(SEM)imagesofthesampleswererecordedonaGemini Zeiss Supra 55 apparatus (operating at 10 kV). BET(Brunauer‐Emmett‐Teller) surface areas of the samplesweremeasuredbyN2adsorptionat196°ConaMicromeriticsASAP2020analyzer.Thesampleswereoutgassedat250°Cfor2.5hundervacuumbeforemeasurement.X‐rayphotoelectronspec‐troscopy (XPS,VGCLAM4MCDanalyzer)wasused todeter‐minetheCo2p,O1s,andC1sbindingenergies(BEs)ofsurfacespeciesusingMgK(hv=1253.6eV)astheexcitationsource.

Hydrogen temperature‐programmed reduction (H2‐TPR)experiments were carried out on a chemical adsorption ana‐lyzer (Autochem II 2920, Micromeritics). The sample (4060mesh,0.025g)wasloadedtoafixed‐bedU‐shapedquartzmi‐croreactor (i.d. = 4mm) and pretreated in a O2 flow (30mlmin−1)at500°Cfor1h.AftercoolinginthesameatmospheretoRT,aHeflow(30ml/min)waspassedtopurgethesamplefor 15 min. Finally, the pretreated sample was exposed to5vol%H2/Armixture(50mlmin−1)andheatedatarampof10°Cmin−1 fromRTto550°C.TheH2concentrationoftheeffluent

wasmonitoredonlinebyachemicaladsorptionapparatus.Thereduction peak was calibrated against that of the completereduction of well‐characterized CuO powders (Aldrich,99.995%).

2.3. Catalyticevaluation

Acontinuousflowfixed‐bedquartzmicroreactor(i.d.=4mm)was used to determine catalyst activity for the oxidation oftoluene.Tominimizetheeffectofhotspots,0.6gquartzsands(4060mesh)wasusedtodilutethesample(0.1g).Thetotalflowrateofthereactantmixture(0.1%toluene+O2+N2(bal‐ance))was 33.3mlmin−1, giving a toluene/O2molar ratio of1/400andaspacevelocity(SV)of20000mlg−1h−1.Thetolu‐enewas obtained by passing aN2 flow through a bottle con‐taining pure toluene (AR) chilled in an ice‐water isothermalbath.theSVwaschangedthroughtheamountofsample.Inthecaseofwatervaporaddition,3.0vol%H2OwasintroducedbypassingthefeedstreamthroughawatersaturatoratRT.Reac‐tants and productswere analyzed online by a gas chromato‐graph (GC‐2010, Shimadzu) equippedwith a flame ionizationdetector(FID)andathermalconductivitydetector(TCD)usingastabilwax@‐DAcolumn(30min length) forVOCseparationanda1/8inCarboxen1000column(3minlength)forperma‐nentgasseparation.Thecarbonbalancethroughouttheinves‐tigationwasestimatedtobe99.5%.

3. Resultsanddiscussion

3.1. Crystalphasecomposition,morphology,andsurfacearea

Figure1showstheXRDpatternsoftheCo3O4samples.Thetwo samples possessed a cubic Co3O4 crystal structure withwell‐indexed planes (JCPDSPDF #74‐1657). The difference indiffraction intensity reflected the discrepancy in crystallinity.AscanbeseenfromFig.2,theparticlesoftheCo3O4bulksam‐plewere irregularpolyhedra.TheCo3O4samplederived fromthe ethylenediamine‐assisted hydrothermal route was com‐posedofmicrosphericalentitiesasseverallayersofanumberofnanoplates(Fig.2(b)(d)).Withachangeinthepreparation

10 20 30 40 50 60 70 80

(12

8)

(44

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2) (40

0)

(22

2) (

311)

(22

0)

(11

1)

(1)Inte

nsi

ty

2 ( o )

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Fig.1.XRDpatternsofCo3O4bulk(1)andCo3O4microspheres(2).

FangWangetal./ChineseJournalofCatalysis35(2014)1475–1481 1477

conditions(addedamountofethylenediamineorhydrothermaltemperature), themorphology of theCo3O4 samples obtainedwasirregular(Fig.3).Therefore,weinvestigatedindetailonlythe Co3O4 bulk and Co3O4 microsphere samples. The surfaceareasof theCo3O4bulkandCo3O4microspheresampleswere9.8and66.2m2g−1,respectively,whereastheCo3O4‐i(i=16)samples showed a surface area of 33.2, 43.5, 50.1, 39.3, 54.2,and26.9m2g−1,respectively.

3.2. Surfacecomposition,Cooxidationstate,andoxygenspecies

Figure4(a) illustratestheCo2p3/2XPSspectraofthesam‐ples. The Co 2p3/2 signal at 780.0 eV showed the presence ofsurfaceCo3+ species,while theCo2p3/2 signal at781.9 eV to‐gether with the shake‐up satellite at 785.5 eV confirms thepresenceofsurfaceCo2+species[20].ItcanbeobservedfromTable 1 that the surface Co3+/Co2+ molar ratio (1.44) of the

4 μm

(c)

20 μm

(b)

4 μm

(d)

200 nm

(a)

Fig.2.SEMimagesofCo3O4bulk(a)andCo3O4microspheres(bd).

20 μm

(b)

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20 μm

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20 μm

(e)

20 μm

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Fig.3.SEMimagesofCo3O4‐1(a),Co3O4‐2(b),Co3O4‐3(c),Co3O4‐4(d),Co3O4‐5(e),andCo3O4‐6(f).

772 777 782 787 792

781.9

(2)

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nsi

ty

Binding energy (eV)

(1)

780.0 (a)

527 529 531 533 535

(b)

(2)

(1)

533.4 531.8

530.3

Inte

nsi

ty

Binding energy (eV)

529.3

Fig.4.Co2p3/2(a)andO1s(b)XPSspectraofCo3O4bulk(1)andCo3O4microspheres(2).


Co3O4microspherewas lower than that (1.65) of Co3O4 bulk,indicatingahigher surface Co2+ concentration in the former.That is, theCo3O4microsphere samplepossessedmoreoxy‐genvacanciesthanthebulkcounterpart.Itiswellknownthattheadsorbedoxygenspeciesconcentrationisassociatedwiththeoxygenvacancydensity.Foranoxygen‐deficientmaterial,more oxygen vacancies give a higher oxygen adspecies con‐centration.ThiswassubstantiatedbytheO1sXPSresult.AsshowninFig.4(b),anasymmetricalO1sXPSsignalwasrec‐orded for each sample, which was deconvoluted into thepeaksofseveralkindsofsurfaceoxygenspecies.Theoxygenadspeciesat529.3,530.3,531.8,and533.4eVwereassigna‐bletothesurfacelatticeoxygen(Olatt),adsorbedoxygen(Oads,e.g.,O2,O22,orO),hydroxyland/orcarbonatespecies,andadsorbedmolecularwater[21,22],respectively.ComparedtotheCo3O4bulksample,theOads/Olattmolarratioofthemicro‐sphericalCo3O4samplewasmuchhigher,indicatingahigherOadsconcentration.

3.3. Reducibility

Figure5(a)illustratestheH2‐TPRprofilesoftheCo3O4sam‐ples. The reduction of Co3O4 proceeds via the sequence ofCo3O4→CoO→Co0[9].Thefirstpeakat227230°CwasduetothereductionofCo3+toCo2+andtheremovalofoxygenadspe‐cies.The reductionpeaks at279292 and316341 °C corre‐spondedtothereductionofCo2+toCo0[23].IfthecobaltionsinCo3O4wereonlyCo3+andonlyCo2+andreducedtoCo0,theH2consumptionwouldbe18.07and13.33mmolg−1,respectively.Actually, the H2 consumptions of the Co3O4 bulk and Co3O4microspheresampleswere16.08and15.48mmolg−1,respec‐

tively. Furthermore, the low‐temperature H2 consumption(3.22mmolg−1)oftheCo3O4bulksamplewashigherthanthat(3.10mmol g−1) of the Co3O4microsphere sample, indicatingthat therewasmoreCo3+ inCo3O4bulk(i.e., theCo3O4micro‐spheresamplepossessedahigheroxygenvacancyconcentra‐tion and hence a higher oxygen adspecies concentration).Therefore, the cobalt species in the Co3O4 sampleswere pre‐sent in a mixed valence (Co3+ and Co2+), which was in goodagreementwiththeXPSresults.

Itisbettertoevaluatethelow‐temperaturereducibilityofasample using the initial (where less than 25% oxygen in thesamplewasremovedforthefirstreductionpeak)H2consump‐tion rate [24]. Figure 5(b) shows the initial H2 consumptionrateasafunctionofinversetemperatureoftheCo3O4samples.Obviously, the initial H2 consumption rate of the nano‐plate‐aggregate Co3O4 microsphere sample was higher thanthat of the Co3O4 bulk sample. This difference in low‐tem‐perature reducibilitywas in consistentwith the difference intheirOadsconcentrationsandcatalyticperformance.

3.4. Catalyticperformance

Inthequartzsandblankexperiment,noconversionoftoluenewasobservedbelow400 °C, indicating thatunder the adoptedconditions therewasnooccurrenceofhomogeneousreactions.Figure 6(a) shows catalytic activity of the samples for toluenecombustion.ItcanbeclearlyseenthatthemicrosphericalCo3O4sampleoutperformedthebulkcounterpart,withtheT10%,T50%,andT90%(temperaturesrequiredfortolueneconversionof10%,50%, and 90%, respectively) of 190, 230, and 254 °C at SV =20000mlg−1h−1(Table1),respectively.Toluenewascompletely

Table1 Surfaceelementcompositions,H2consumption,andcatalyticactivitiesoftheCo3O4bulkandCo3O4microspheresamples.

SampleSurfaceelementcomposition H2consumption(mmolg−1) Catalyticactivity

Co3+/Co2+molarratio Oads/Olattmolarratio 250°C >250°C T10%(°C) T50%(°C) T90%(°C)Co3O4bulk 1.65 0.38 3.22 12.86 230 273 304Co3O4microsphere 1.44 1.03 3.10 12.38 190 230 254

Reactionconditions:tolueneconcentration=0.1%,toluene/O2molarratio=1/400,SV=20000mlg−1h−1.

80 200 320 440

341

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227

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onsu

med

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Init

ial H

2 co

nsu

mp

tion

rat

e (m

mol

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)

1000/T (K1)

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Fig.5.H2‐TPRprofiles(a)andinitialH2consumptionrateasafunctionofinversetemperature(b)ofCo3O4bulk(1)andCo3O4microspheres(2).


oxidizedtoCO2andH2OovertheCo3O4samples,andtherewerenoincompleteoxidationproducts,assubstantiatedbythecarbonbalance (99.5%) in each run. To better evaluate the catalyticactivityof the samples,weuse the specific reaction rates (nor‐malizedbyweightamountandsurfaceareaofthesample)versusreactiontemperature,asshowninFig.6(b)and(c),respectively.It is observed that the changing trend in specific reaction ratenormalizedbyweightamountofthesampleversustemperaturewasrathersimilartothatfortolueneconversionversustemper‐ature,butdifferentfromthespecificreactionratenormalizedbysurfaceareaofthesampleversus temperature.Thisresult indi‐cated that the surface area had an important influence on thecatalyticactivityofthesample.

To examine the effect ofwater vaporon the catalyticper‐formance,we conducted tolueneoxidation in the presence of3.0vol%watervaporoverthemicrosphericalCo3O4sample.AsshowninFig.7,theadditionofwatervaporat260°Cdidnotleadtoasignificantdecreaseintolueneconversion,butintro‐duction of water vapor at 220 °C induced a drop in tolueneconversionby4%.Thisresultwaspossiblyduetothecompeti‐tiveadsorptionofwater,toluene,andoxygen.Whenthewatervaporwascutoff,tolueneconversionat220°Cwasrestoredtoalmost the initial value in the absenceofwatervapor.There‐

fore,thedeactivationduetowatervaporintroductionwasre‐versible.

Figure8showstheeffectofSVonthecatalyticactivityoftheCo3O4microspheresample.Asexpected,thetolueneconversionincreasedwiththedropinSV.Inordertoexaminethecatalyticstability,wecarriedoutthe100hon‐streamreactionexperimentovertheCo3O4microspheresampleat250°Cand20000mlg−1h−1. As shown in Fig. 9, no significant loss in activity was ob‐

100 150 200 250 300 3500

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Fig.6.Tolueneconversion(a),specificreactionratenormalizedbycatalystamount(b),andspecificreactionratenormalizedbythesurfaceareaofthecatalyst(c)asafunctionoftemperatureoverCo3O4bulk(1)andCo3O4microspheres(2).Reactionconditions:0.1%toluene,toluene/O2molarratio=1/400,SV=20000mlg−1h−1.

0 100 200 300 400 500 6000

20

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H2O off H2O off

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H2O onH2O on

Tol

uen

e co

nve

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n (

%)

Time (min)

H2O on

(1)

Fig.7.Theeffectof3.0vol%watervaporonthecatalyticactivityat220°C(1)and260°C(2)overCo3O4microspheres.Reactionconditions:0.1%toluene,toluene/O2molarratio=1/400,SV=20000mlg−1h−1.

100 150 200 250 3000

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40000 ml g1 h1 20000 ml g1 h1

Tol

uen

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Temperature (oC)

10000 ml g1 h1

Fig. 8. Toluene conversion as a function of reaction temperature atdifferentSVvaluesoverthenanoplate‐aggregatemicrosphericalCo3O4catalyst. Reaction conditions: 0.1% toluene, toluene/O2molar ratio =1/400.

0 20 40 60 80 10050

60

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100

Tol

uen

e co

nver

sion

(%

)

Time (h) Fig.9.Toluene conversion as a functionof on‐stream reaction timeoverthenanoplate‐aggregatemicrosphericalCo3O4sample.Reactionconditions: 0.1% toluene, toluene/O2 molar ratio = 1/400, SV =20000mlg−1h−1,250°C.


served.Thisresultdemonstratedthat themicrosphericalCo3O4samplewasstableundertheadoptedconditions.

Inthepastyears,manymaterialshavebeenusedasthecat‐alyst for toluene combustion. The activities of these catalystsare summarized inTable2.Usually, the specific reaction ratenormalizedbythesampleamountisusedtocomparethecata‐lyticactivityofdifferentsamples.Atagivenreactiontempera‐ture(150or250°C),thespecificreactionrate(0.0376mmolg−1h−1at150°Cor0.711mmolg−1h−1 at250 °C)over theCo3O4microshperes was much higher than those over Mn3O4 [25],‐Mn2O3[25],‐MnO2[25],bulkCo3O4[17],LaMnO3[26],and5 wt% Au/CeO2 [27], but lower than those overCo3O4‐HT‐CTAB [2], mesoporous Co3O4 [17,18], and 0.5 wt%Pd/LaMnO3[28].

It is well established that the oxidation of organics over atransitionmetaloxideinvolvesaMarsvanKrevelenmechanism,whereorganicmoleculesareoxidizedbythelatticeoxygenofthemetal oxide, and the partially reduced metal oxide is thenre‐oxidizedby the gas phase oxygen [2931].Wang et al. [31]attributed the higher reactivity ofmanganese oxide to the im‐provement in oxygen activation ability, which enhanced thecombustion of ethanol and acetaldehyde. In the case of Co3O4,latticeoxygencouldbeconsumedbyreactionwithtolueneandthenreplenishedbygasphaseoxygen[32,33].Thus, the latticeoxygenof cobaltoxide isof great importance in tolueneoxida‐tion. The low‐temperature reducibility reflects the reactivity ofthelatticeoxygeninCo3O4.AsshowninFig.5,thelatticeoxygenreactivity (i.e., low‐temperature reducibility) of the Co3O4 mi‐crosphereswashigher than thatofCo3O4bulk. Surfaceoxygenvacanciesalsohaveanimportantroletoplay[34,35].Thepres‐enceofoxygenvacancies favors theactivationofoxygenmole‐culestoactiveoxygenadspecies.ThemicrosphericalCo3O4sam‐plepossessedahigheroxygenadspeciesconcentration(whichisrelated to the surface oxygen vacancy density) than the Co3O4bulksample, ingoodagreementwith their catalyticactivity se‐quence. In addition, the surface area (66m2 g−1) of nanoplate‐aggregateCo3O4microsphereswasmuchhigherthanthat(10m2g−1)ofCo3O4bulk.Therefore,weconcludethatthelargesurfacearea, high oxygen adspecies concentration, and good low‐tem‐peraturereducibilityaccountedforthegoodcatalyticperforman‐ce of the nanoplate‐aggregate Co3O4 microspheres for toluenecombustion.

4. Conclusions

Thenanoplate‐aggregatemicrosphericalCo3O4catalystwasprepared using an ethylenediamine‐assisted hydrothermalstrategy. This catalyst had a cubic crystal structure and wascomprised of nanoplate‐aggregate microspheres. The micro‐spherical Co3O4 sample outperformed the bulk counterpart,givingtheT50%andT90%of230and254°CatSV=20000mlg−1h−1, respectively. The large surface area, high surface oxygenadspeciesconcentration,andgoodlow‐temperaturereducibil‐ity of the Co3O4 microspheres were responsible for its highcatalyticperformance.

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Table2Comparisonontheactivityofvariouscatalystsfortoluenecombustion.

CatalystReactioncondition

Specificreactionrate(mmolg−1h−1)

Ref.Tolueneconcentration(%) SV(mlg−1h−1) At150°C At250°C

Co3O4microspheres 0.1 20000 0.0376 0.711 ThisworkCo3O4‐HT‐CTAB 0.1 20000 0.164 0.818 [2]BulkCo3O4 0.1 20000 0.0164 0.246 [17]MesoporousCo3O4 0.1 20000 0.246 0.818 [17]MesoporousCo3O4 0.1 20000 0.778 0.818 [18]Mn3O4 0.1 15000 0 0.522 [25]‐Mn2O3 0.1 15000 0 0.00614 [25]‐MnO2 0.1 15000 0 0 [25]LaMnO3 0.19 178h−1 0.000277 0.00554 [26]5wt%Au/CeO2 0.7 186 0 0.00533 [27]0.5wt%Pd/LaMnO3 0.1328 18000h−1 0.293 0.880 [28]


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GraphicalAbstract

Chin.J.Catal.,2014,35:1475–1481 doi:10.1016/S1872‐2067(14)60072‐3

Nanoplate‐aggregateCo3O4microspheresfortoluenecombustion

FangWang,HongxingDai*,JiguangDeng,ShaohuaXie,HuanggenYang,WenHan BeijingUniversityofTechnology

Nanoplate‐aggregate microspherical Co3O4 prepared by the ethylene‐diamine‐assisted hydrothermal route exhibits good catalytic perfor‐mance for tolueneoxidationbecause of its high surface area and con‐centrationofadsorbedoxygenandgoodlow‐temperaturereducibility.

nanoplate-aggregate co3o4 microspheres for toluene combustion

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