Catalyst Preparation And Application Research For Ethanol Steam Reforming

Energy is the foundation of the national economic development, H2pollution-freeenergy is replaceable of fossil fuel, and that the process of hydrogen production fromethanol steam reforming have been proved viable. How to develop a catalyst with lowtemperature, high activity and high selectivity for ethanol steam reforming is of greatsignificance for the development of fuel cells.La₂O₃-ZrO₂support was prepared by coprecipitation method with series ofAg-Fe/La₂O₃-ZrO₂, Ni-Fe/La₂O₃-ZrO₂, Ni-Mn/La₂O₃-ZrO₂catalysts were prepared byimpregnation method. The crystal phase structure, redox property and carbon depositionmorphology of catalysts were characterized by X-ray powder diffraction （XRD）,Temperature programmed oxidation （TPO）, Temperature programmed reduction （TPR）and the scanning electron microscope （SEM） results. The activity of catalysts in ethanolsteam reforming was studied through minitype active evaluation device. The effects of thecatalyst composition including the atoms mole ratio of La and Zr in carrier, the load ofactive components and the active atoms mole ratio on the ethanol conversion werediscussed. The results showed that the catalysts were remarkable and stable tetragonalphase when La:Zr=2:8; The （4Ni1Fe）4（2La8Zr） catalyst with the mole ratio of Ni:Fe=4:1and the mole ratio of active components to support is1:4exhibit best catalytic activity andstability in ethanol steam reforming, with no inactivation phenomenon between523-873K.Reaction temperature significantly affected the ethanol conversion and reaction selectivity,the ethanol conversion on （4Ni1Fe）4（2La8Zr） catalyst is closed to100%at773K; Thestudy also found that all catalysts appear a certain degree of inactivation phenomenon athigh temperature. The TPO and SEM characterization for Ni-Fe/La₂O₃-ZrO₂catalystsshowed that carbon deposition is the main reason for catalyst deactivation. The form andamount of carbon deposition existed on catalyst is closely related to the Ni/Fe ratio, that isthe increase of Fe active component contributes to the generating of carbon nanotubeswhich has little impact on catalytic activity.To study the ethanol steam reforming reaction mechanism of （1Ag20Fe）20（2La8Zr）catalyst, the catalyst activity of ethanol, aldehyde, acetic acid, acetone, CO, CH₄, andCO₂steam reforming reaction were evaluated respectively. The results showed that tworeaction paths of ethanol-ethyoxyl-aldehyde-final products （H2, CO₂） andethanol-ethyoxyl-aldehyde-acetone-final products were found on the catalyst; And thatCO water gas shift reaction （WGSR） always happens accompanying in the reaction route.Moreover, WGSR activity of （1Ag20Fe）20（2La8Zr） catalyst is highest at873K and theCO conversion rate grows slowly after823k. The CH₄steam reforming is increasing with the increasing temperature but the reaction activity is very low during the wholetemperature range on （1Ag20Fe）20（2La8Zr） catalyst（The maximal methane conversionis14.21%at823K）.