Influence of Calcination Temperature on the Performance of Cu-Al-Ba Catalyst for Hydrogenation of Esters to Alcohols

Abstract

Novelchromium鄄freeCu鄄Al鄄Bacatalystswerepreparedbyco鄄precipitationandwerecalcinedat differenttemperatures.Theirperformanceduringthehydrogenationofpalmoilesterstohigheralcoholswasevaluated inanautoclave.Resultsshowedthatthecatalyticpropertiesofthecatalystsweregreatlyinfluencedbythecalcination temperatures.Theyieldofhigheralcoholsshowedthreestepswhenthecalcinationtemperatureofthecatalystswas raisedfrom150to750 益.Thethermogravimetric(TG鄄DTG)curvesoftheprecursoralsoexhibitedthreestepsrelatedto massloss.X 鄄 raypowerdiffraction(XRD),X 鄄 rayfluorescence(XRF),transmissionelectronmicroscopy鄄energy dispersivespectrometry鄄selectedareaelectrondiffraction(TEM鄄EDS鄄SAED),N 2 鄄 physisorption,andtemperature鄄 programmedreduction(TPR)characterizationrevealedthatthecatalystswereobtainedfromamalachite鄄boehmite鄄 BaCO 3 precursor.Aftercalcinationat300or550 益,thecatalystswerefoundtobecomposedofcrystallineCuOand BaCO 3 aswellasamorphousAl 2 O 3 .AmorphousAl 2 O 3 hasalargesurfaceareawhichresultsinahighdispersionof CuO.Rod鄄likeBaCO 3 helpsintheprovisionofmicropores.TheformationofBaAl 2 O 4 atacalcinationtemperatureof 750 益 destroystheamorphousstructureandcausesasharpdeclineinthesurfaceareaandporevolumeofthecatalyst andthiscausesCuOaggregation.Anoptimalhigheralcoholyieldof92.3%wasobtainedovertheCu鄄Al鄄Bacatalyst thatwascalcinedat550 益 duetoitslargersurfacearea,largerporevolume,andhigherdegreeofCuOdispersion.