促进钾盐为水煤气变换反应的钌_交流催化剂

co变换催化剂

PromotedpotassiumsaltsbasedRu/ACcatalystsforwatergasshift

reaction

YajuanMaa,BingLiua, ,MengmengJinga,RenyuanZhangb,JunyuChena,YuhuaZhanga,JinlinLia,

KeyLaboratoryofCatalysisandMaterialsSciencesoftheStateEthnicAffairsCommission&MinistryofEducation,CollegeofChemistryandMaterialScience,South-CentralUniversityforNationalities,Wuhan430074,PRChinab

CollegeofChemistryandChemicalEngineering,XiaMenUniversity,XiaMen361005,PRChina

a

highlights

TheadditionofpotassiumsaltimprovedtheRu/ACactivityoverWGSreaction. COconversionincreasedfrom13.6%forRu/ACto56.1%forK2CO3-Ru/ACat300°C. Theincreaseoftheactivitywasduetothereductiontemperatureofthecatalyst. Thehighhygroscopicabilityofthesaltalsoincreasedthecatalystactivity.

articleinfoabstract

Inthiswork,wehavepreparedseveralkindsofpotassiumsaltsdopedRu/ACcatalystsandsystematicallystudiedtheircatalyticactivitiestowardswater–gasshift(WGS)reaction.ActivitytestingindicatedthatK2CO3dopedRu/ACcatalyst(Ru-K2CO3/AC)showedhighercatalyticperformancethanKOHandKOAcdopedRu/ACcatalysts,methaneselectivitydecreasedmostafterdopingKOH.AlthoughtheparticlesizeofRunanoparticlesinRu-K2CO3/ACcatalystwaslargerthanthatoftheparentRu/ACcatalyst,H2-TPRindicatedthatRuOxwasreducedatmuchlowertemperature,suggestingaweakerinteractionbetweenRuOxandthesurfacefunctionalgroupofactivecarbonafterthedopingofK2CO3.Thus,Runanoparticlesinteractedstrongerwiththereactionmolecules(COandH2O),leadingahighercatalyticactivity.Inaddi-tion,thedopingofK2CO3onthesurfaceofRu/ACcatalystalsoincreasedtheconcentrationofwateraroundRuactivesiteduetothehygroscopicability.Interestingly,itwasalsofoundthatthepreparedmethodalsogreatlyaffectedthecatalystactivity.Iftheactivecarbonwas rstlycoatedwithK2CO3,fol-loweddepositionofRumetalnanoparticles,(calledRu/K2CO3-ACcatalyst),theactivitydecreasedremarkablyascomparedtoRu-K2CO3/AC.ThelowcatalyticactivityofRu/K2CO3-ACwasmainlyduetotheaggregationofRunanoparticles.

Ó2015ElsevierB.V.Allrightsreserved.

Articlehistory:

Received27June2015

Receivedinrevisedform19October2015Accepted26October2015

Availableonline14November2015Keywords:

Water–gas-shiftreactionRutheniumbasedcatalystsPotassiumsaltsDoping

1.Introduction

Thewater–gasshift(WGS)reaction(CO+H2O?H2+CO2,DH=41.2kJmolÀ1)isoneofthemostfundamentalreactionsfortheremovalofCOandproductionofhighpurityH2fromsyngas.Thisreactioncanbeusedfortheupgradingofthereformedgasinfuelcells,asitiseffectivetoreduceCOtoaverylowcontent,avoidingthepoisoningofPtelectrodes[1].Inaddition,WGSreac-tionhasalsoplayedakeyroleinadjustingtheH2/COratioforFis-cher–Tropsch(FT)processes[2]andprovidinghydrogen-richCorrespondingauthors.Tel./fax:+862767842572.

E-mailaddresses:liubing@(B.Liu),lijl@(J.Li).

/10.1016/j.cej.2015.10.119

1385-8947/Ó2015ElsevierB.V.Allrightsreserved.

streamsforfuelcells[3].Industrially,inordertoproducehighpur-ityH2atthehighestpossibleCOconversion,two-stagemethodisappliedinWGSreaction:ahightemperatureshiftreactionoperat-ingat300–450°CbytheuseofFe-basedcatalysts(e.g.,Fe2O3/Cr2O3)andalowtemperatureshiftreactionoperatingat200–270°CbytheuseofCu-basedcatalysts(e.g.,Cu/ZnO/Al2O3)[4].However,someproblemsstillremaininthecomicaltwo-stageWGScatalysts.ThecatalyticactivityofFe2O3/Cr2O3isrelativelowatlowreactiontemperatures.Furthermore,theFe2O3/Cr2O3containsabout1–2wt.%hexavalentchromium(Cr6+),whichishighlytoxictohumans,organismsandtheenvironment[5].TheCu/ZnO/Al2O3catalystsdeactivatedatanoxidizingatmosphere[6].Therefore,theneedforthedevelopmentofhighactiveWGScatalystsstillremainsanimportantgoalinWGSreactions.