Study On Ni, Ru Catalysts Supported On Composite Supports For Hydrogen Production From Steam Reforming Of Ethanol

Energy crisis and environmental problems are two difficult problems in current world.Hydrogen energy is a clean and high energy content source.Ethanol,which can be prepared from fermentation of agricultural residues,is a renewable resource. Hence steam reforming of ethanol for hydrogen production is attracting more and more attention.In this thesis,different series of composite supports were prepared by impregnation method and solid-phase burning method,and various Ni and Ru catalysts were prepared by impregnation method.Catalytic properties of the samples were evaluated in ethanol steam reforming(ESR) reaction.Specific surface areas of the supports were measured by BET.The catalysts were characterized by means of X-ray diffraction(XRD),temperature programmed reduction(TPR),and the coke deposition of catalysts was investigated by thermogravimetric(TG).In the first part,La₂O₂CO₃ was prepared by La₂(CO₃)₃ calcination method in air, ZnO-La₂O₂CO₃ with different mole ratio of Zn:La and catalysts Ru/ZnO, Ru/La₂O₂CO₃,Ru/ZnO-La₂O₂CO₃ were prepared by impregnation method.The results showed that Ru_xLa_yO existed in Ru/ZnO-La₂O₂CO₃,and the catalyst with 1:1 mole ratio of Zn:La in the support performed better for ESR reaction,the conversion of ethanol was 100%,the selectivity of H₂ was higher than 90%,and the selectivity of CO was lower than 1%at 450℃.In the second part,MgO-La₂O₂CO₃ with different mole ratio of Mg:La and catalysts Ni/MgO,Ni/La₂O₂CO₃ Ni/MgO-La₂O₂CO₃were prepared by impregnation method.The results showed that the catalysts Ni/MgO-La₂O₂CO₃ performed well activity and selectivity for ESR reaction.The catalyst with the support of 1:2 mole ratio of Mg:La performed the optimum activity,selectivity and stability for ESR reaction at low temperature,the conversion of ethanol could reach 100%at 400℃.In the third part,MgO,CeO₂ and MgO-CeO₂ with different mole ratio of Mg:Ce were prepared by solid-phase burning method,catalysts Ni/MgO,Ni/CeO₂ and Ni/MgO-CeO₂ were prepared by impregnation method.Specific surface areas of the supports were measured by BET,The results indiicated that the supports prepared by solid-phase burning method had high surface area,well dispersed NiO,bulk-like NiO phase and the NiO interacting with the support co-existed in Ni/CeO₂ and Ni/MgO-CeO₂,The catalysts supported on composite supports exhibited better performence than the catalysts supported on single supports,and the catalyst with the support of 1:1 mole ratio of Mg:Ce performed the optimum activity,selectivity and stability for ESR reaction at low temperature.In the last,Ni-Ru/MgO-CeO₂ were prepared,effect of the addition of a small amount of Ru on the Propertis of Catalyst for Hydrogen Production from Steam Reforming were investigated.The results showed that the ability of Ni for rupture of C-C bond was similar with that of Ru.The addition of Ru could improve H₂ selectivity,reduce CO selectivity,and restrain the formation of C₂H₄ and C₂H₆. Meanwhile,the ability to resist against carbon deposition of NMC could be enhanced by the addition of Ru,resulting in the improvement of the stability for ESR reaction at low temperature.