Study On Catalysts For Hydrogen Production From Chitosan And Glycerol Biomass

Hydrogen production from biomass is one of the important projects and has a very promisingprospect in the field of new energy development. According to recent researches, a relatively hightemperature is neededto producehydrogen byusing the method of biomass gasification bythermalcracking or through catalytic reforming on biomass derivatives which will lead to more energyconsumption with low efficiency and economic benefits. In this paper, we studied hydrogenproduction from biomass in two directions: On one hand, a series of metal oxide and inorganicnitratewerechosenascatalysttoinvestigatethecatalyticthermalcrackingprocessesofchitosan.Wehope to find some admirable samples which can accelerate the thermal crackingprocess of chitosananddecreaseits thermal decomposition temperature bythermal analysis method. Onthe other hand,we investigated steam reforming of glycerol which is the main by-product in biodiesel project forhydrogen production over highly active and relatively cheap Ni supported catalysts. Promisingsupports were chosentoimprovethe activityofNi evenatlowtemperatures. Thentwo componentssupported and bimetallic catalysts were made to modify the Ni based catalysts achieved before, thehighlyactiveandstablecatalystsforhydrogenproductionfromsteamreformingofglycerolcouldbefound at last. The physical and chemical property of catalysts was characterized by H2-TPR, N2adsorption,XRDandTEMtechniques.Themainresultsweresummarizedasfollows:1. In regard to the thermal cracking processes of chitosan, doping inorganic oxides likevanadium oxide andmetal nitrates such as copper nitrate or nickel nitrate to chitosan can obviouslyacceleratethermal crackingprocess of chitosananddecrease itsthermal decomposition temperature.Thesecompoundsareexcellentcatalyststoproducehydrogenbychitosandecomposition．2. CeO2, Al2O3and MgO supported Ni catalyst were prepared by incipient impregnation, theactivityofNi basedcatalyst inhydrogenproductionbyglycerol steam reformingwas studied atlowtemperatures. The results show that relatively high glycerol conversion(85.7%) were achieved at500oC withNi/Al2O3catalystduetoits highsurfacearea andlargeporevolume. However,Ni/CeO2sample was more active and stable at low temperature, there was almost no deactivation detectedafter20hours reaction at400oC. Base oxide supports (CeO2, MgO) were more effective than acidoxidesupportsinpreventingtheformationofCOandCH4. 3ModifiedNi/CeO2catalystswerepreparedbyaddingAl2O3orActivatedcarbon.Itwasfoundthat thedispersion andofCeO2andNi species wereimproved byaddingAl2O3whichledto higheractivity of Ni catalysts. Ni/CeO2-25%Al2O3showed the highest activity among this series ofcatalysts. The glycerol conversion was90%and theH2yield was88%overNi/CeO2-25%Al2O3at400oC. Good catalytic performance was also achieved on the AC modified Ni/CeO2catalysts. Theglycerol conversion was93%and the H2yield was89%over Ni/CeO2-10%AC at400oC. Thestability of modified Ni/CeO2catalysts did not decline with a moderate adding amount of Al2O3orAC.4. A series of Ni/CeO2-25%Al2O3bimetallic catalysts were prepared by adding Fe, Co, Cu.According to the experimental results, the activity of the catalysts for glycerin reforming increasedwhen the Ni/Co mass ratio was appropriate. Ni-40%Co/CeO2-25%Al2O3catalysts showed thehighestactivityamongNi-Cobimetalliccatalysts.TheinteractionbetweenNiandCospeciesdidnotmake the catalyst more stable, on the contrary, the activityof catalyst decreased obviouslyafter20hreaction at400oC. The performance of Ni/CeO2-25%Al2O3catalyst was inhibited with the additionofFeorCuwhichwasnotapplicableforhydrogenproductionfromsteamreformingofglycerol.