第十七屆全國催化學術(shù)集口頭墻報pa384

TuningcatalyticperformancesofcobaltcatalystsforH2production

viavariationofthetypeofcarbonsupport

HuiZhang1*,Y.AAhamld2,FeiHuang1,L.A.Petrov2

1SchoolofChemistryandChemicalEngineering,SouthwestPetroleumUniversity,Chengdu610500,;

2SABICChairofCatalysis,KingAbdulazizUniversity,Jeddah21589,SA

hui

：Ammonia position;H2production;Cobaltcatalysts;Carbonsupports

Hydrogen,asapotenialrenewablecleanenergy,hasbeenattractingmoreandmoreattentioninrecentyears[1].Liquidammonia,asahydrogencarrier,hastheadvantagesofbothhighenergydensityandhighhydrogenstoragecapacity(17.7%),whiakesammoniasuitableforon-boardgenerationofCOxhydrogenbycatalyticammonia position[2].Thedevelopmentofhighlyactive,stableandcheapsolidcatalysttobenifitammonia positionatlowtemperatureisstillachanllagingissuetodate.Anidealcatalystsupportforammonia positionshouldpossesshighelectronicconductivity,thermalstabilityandsurfacearea[2,3].NovelcarbonmaterialsexceptactivatedcarbonssuchasMulti-wallcarbonnanotubes,singlewallcarbonnanotubeandreducedgrapheneoxides,havebeenwidelyemployedascatalytcarriersduetotheirexcellentmechanicalstabilityandspecialelectrinicpropeties.

Severalcarbonmaterialsupportswereobtainedassupport:(1)Muti-wallcarbonnanotubes( Ts);(2)activecarbonwithdifferenttexturalstructure,AC-1,AC-2andAC-3;(3)Singlewallcarbonnanotubes, Ts;(4)reducedgrapheneoxides,RGO.Theserialofcarbonmaterials-supportedcobaltcatalysts(5wt%)wereprepared,labeledlike Ts,Co/AC-1,Co/AC-2,Co/AC-3, TsandCo/RGO,respectively.ThesampleswerecharacterizedusingXPS,N2-TPD,TEM,XRDandH2-TPRtechniques.Theammonia positionto

hydrogenreactionwascarriedoutinafixed-bedreactoratatmosphericpressure.

Table1.Texturalpropertiesofcarbonmaterials

Surfacearea Totalporevolume Averageporediameter

Carbonsupport

m2.g-1 cm3.g-1

nm

Ts

169.3

0.41

9.7

AC-1

2954.0

1.56

2.1

AC-2

695.2

0.41

2.1

AC-3

71.3

0.08

4.5

*OpenFundofStateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,SouthwestPetroleumUniversityof(PLN1132)；KingAbudulazizUniversityofSaudiArabia(ProjectHiCi-1432/4-4).

Table1reportsthephysicalcharacteristicsofthesupportmaterials.ItisapparentthatthreetypesofAChaveverydifferenttexturalcharacteristics.ThesurfaceareaandporevolumeofAC-1are2954m2g-1and1.6cm3g-1,respectively,whicharemuchlargerthanthesamevaluesoftheothertwotypesofACsupports.TheAC-3hasthesmallestsurfaceareaandporevolumeof71.3m2g-1and0.08cm3g-1,respectively,whileitsaverageporediameterof4.51nmwasthelargestamongthethreetypesofusedAC.Thesurfacearea,porevolumeandaverageporediameterofTssupportwas169.3m2/g,0.41cm3/gand9.7nm,respectively.Theorderofdecreasing

surfaceareaofACand TsusedascatalystsupportwasAC-1>AC-2> Ts>AC-3.

Fig.1.CatalyticactivitiesofCocatalystsforNH3 positionatdifferentreactiontemperatures

(A)andGHSV(B).

Fig.1showstheeffectofreactiontemperature(Fig.1(A))andNH3GHSV(Fig.1(B))onammoniaconversionondifferentcatalysts.FromFig.1(A)follows,thatNH3conversionwasreasedwithreasingofthereactiontemperature,suggestingthathighreactiontemperatureisfavorableforammonia positionreaction.Onthecontrary,ammoniaconversiondecreasedwiththe reaseofNH3GHSV,butthisdependencewasnotverystrong(seeFig.1(B)).Thus,theeffectofreactiontemperatureoncatalyticperformancewasgreaterthantheeffectofNH3GHSV

forammonia position.

CombiningthedatainFig.1(A)and(B),itfollowsthatregardlessofthereactiontemperatureandGHSV, TscatalysthasshownthehighestNH3conversion.Thecatalyticactivitiesofthepreparedcatalystswererankedinthefollowingorder: Ts>Co/AC-1>Co/AC-2>Co/AC-3>Co/RGO> Ts.

AhighlyefficientCocatalystforCOx-H2productionviaNH3 positionshouldhavethecombiningpropertiesofelectronictransportpropertiesandappropriatecarbonsupportstructure.

Acknowledgement.HuiZhangthankstheSABICChairofCatalysisforprovidingfinancialsupportduringhisstayinSaudiArabiaforexperimentresearch.

References

C.M.White,R.R