Abstract:
The objective of this research was to obtain the suitavle ceriacomposition in the Ni/Al2O3 catalyat to produce high hydrogen yield from ethonolstream reforming process.Four different ceria promoted catalysts that were preparedin laboratory by using deposition method and one commercial catalyst were uesd.Indetermining the calcination temperature,XRD patterns show that the undesirableform of nickel aluminate,NiAl2O4 which is different to reduce,was increased whenthe calcination temperature increased from 350 to 650 oC.Therefore,the calcinationtemperature for Ni/CeO2/Al2O3 chosen was 350 oC.The number of active sites of allcatalyst ewre determined by hydrogen chemisoeption technique.The resultsillustrated that the number of active sites increased as the cerium compositionincreased.In contrast,at very high cerium compostion of 15% the number of activesites decreased because of the lower surface area of support.The reforming reactionwas performed in a packed bed reactor at 650 oC,for 5 hrs.It was found that thecommercial catalyst produced less hydragen and generated higher carbon formationthan those of prepared catalyst.The promoted catalyst was more active andproduced higher hydrogen rate,56 l/hr,that the unpromoted catalyst,52l/hr,and thecommercial catalyst,41 l/hr.Moreover,adding ceria to Al2O3 support can stabilizethe Ni/Al2O3 catalyst.The promoted catalyst gave constant gas rate and gascomposition.According to the experimental results,suitable ceria loading for ethanolstream reforming catalyst was 5-10%.In addition the effect of thermal cracking on thegas production was studied and it was carried out in blank reactor.It was found thatonly 7-10% of total hydrogen production rate was produced by thermal cracking ofethanol