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1、JOURNALOFCATALYSISL~,401-410(1990)CO2ChemisorptiontoCharacterizeCalciumCatalystsinCarbonGasificationReactionsA.LINARES-SOLANO,1M.ALMELA-ALARC6N,ANDC.SALINAS-MARTfNEZDELECEADepartamentodeQuimicaInorgclnicaeIngenieriaQulmica,UniversidaddeAlieante,Alicante,SpainRecei
2、vedMay8,1989;revisedMarch30,1990CO2chemisorption,atdifferenttemperatures,hasbeenstudiedinCaOandintheCaO-carbonsystembymeansofsimultaneousTG-DTA,MS,andXRDtechniques.AsawholethedifferenttechniquesusedshowthatCO2chemisorbsinanirreversiblemannerandismainlyrestrictedto
3、thesurfaceoftheCaOparticles,providedthatthechemisorptiontemperatureislowerthan573K.CO2chemisorptionat573KcanbeusedasatooltomeasuretheexternalsurfaceareaofCaOparticles.SelectiveCO2chemisorptionat573KhasbeenappliedtotheCaO-carbonsysteminthefieldofcatalyticcarbongasi
4、fication.SeveralexamplesaregiventoshowtheusefulnessofthecatalystsurfaceareadeterminedbyCO2chemisorptionininterpretingthecatalyticactivityofcalciumincarbongasification.©1990AcademicPress,Inc.I.INTRODUCTIONsystemprovidesaselectiveandrapidtech-niquetomeasuretheactive
5、sitedensityofTheimportanceofcatalystdispersion,alkalinecatalystoncoal.Hashimotoetal.thatis,theconcentrationofcatalystsites,(4),usingaflashdesorptionmethod(Curie-inthefieldofheterogeneouscatalysishaspointpyrolizer),determinedtheamountofbeenwelldocumented(1).Extensi
6、velitera-oxygentrappedbythealkalinemetal-car-tureexistsonthedeterminationofthebonsystem.Gasificationratesinsteamdispersionofacatalyst,whichisusuallywereproportionaltothechemisorbedoxy-measuredbyoneormoreofthefollowinggen.Cerfontainetal.(5),usingastep-techniques:se
7、lectivechemisorption,X-rayresponseexperimentwithlabeledmole-diffractionlinebroadening,electronmi-cules,havealsorelatedgasificationsitescroscopy,andsmall-angleX-rayscatteringforthealkalinemetal-carbontothe(2).However,inthefieldofcatalyzedamountofCO2chemisorbedbythe
8、cata-carbongasificationtheextentofcatalystlyst.MimsandPabst(6)concludedthatdispersionhasnotbeensufficientlyevalu-therelativereactionratesforalkalinesalt