Study On Ni Nanocomposite Catalysts Prepared By Reverse Microemulsion For Hydrogen Production From Steam Reforming Of Ethanol

This paper studied the composition of the reverse microemulsion system, the preparation, characterization of Ni/CeO2nanocomposite catalysts and its performance for hydrogen production from steam reforming of ethanol. The Ni/CeO2nanocomposite catalysts was prepared by reverse microemulsion, which was characterized for the catalyst structure, morphology, particle size distribution and chemical adsorption performance etc. The catalytic activity of Ni/CeO2nanocomposite catalysts in hydrogen production from steam reforming of ethanol were studied, and compared with other Ni/CeO2catalysts prepared by different methods.In the first part, select the Span80-Tween80as composite surfactant, used the method of visual observation and electrical conductivity to determine the critical composition of the microemulsion system. Used single factor experiments and orthogonal design to optimize the the composition of the microemulsion system. The results showed that Span80-Tween80as composite surfactant (HLB value=8,30wt%),1-butanol as cosurfactant (6wt%),1-octane as the oil phase (44wt%) can get a better microemulsion system, the maximum water solution is3.2ml. The Ni/CeO2nanocomposite catalysts prepared by this microemulsion system have such features with the smaller particle size, good dispersion and no obvious agglomeration. The noteworthy catalytic performance were exhibited in ethanol steam reforming reaction, the ethanol conversion can reach100%at400℃, and the yield rate of H2was around40%and the selectivity rate of CO as low as1.07%.In the second part, the Ni/CeO2nanocomposite catalysts were prepared by CTAB/1-butanol/cyclohexane/water microemulsion system, the performance in steam reforming of ethanol product hydrogen on heating drying and vacuum freeze-drying measured catalysts were compared. The results showed that the Ni/CeO2nanocomposite catalysts prepared by CTAB reversed microemulsion have small particle size and well active component dispersion characteristics, which showed excellent catalytic activity and selectivity. The catalyst measured by vacuum freeze- drying showed the highest performance, and the yield rate of H2can reach42%and the selectivity rate of CO was low to0.35%. The catalysts also exhibited excellent stability and resistance to carbon deposition. It does not appear to deactivation after60hour continuous reaction, the carbon deposition of the catalyst was only0.0616g per gram.In the third part, the performance for hydrogen production from steam reforming of ethanol of Ni/CeO2catalysts prepared by reverse microemulsion method, impregnation method, microemulsion-impregnation method and literature reported method was compared. The results showed that the Ni/CeO2nanocomposite catalysts prepared by the reverse microemulsion and literature reported method have better activity and selectivity in hydrogen production from ethanol steam reforming reaction. In contrast, the catalyst prepared by reverse microemulsion exhibited higher H2yield and low CO selectivity. Such Ni/CeO2nanocomposite catalysts does not appear deactivation after60h, the yield rate of H2and selectivity of products remained basically unchanged, showed excellent stability.