Study On Ni (Fe, Co) Catalysts Supported On La₂O₂CO₃ For Hydrogen Production From Steam Reforming Of Ethanol

Energy and environment is the most major problem for the human society sustainable development in future. Hydrogen energy attracts much attention because it is a clean and high energy content source. Meanwhile, ethanol, which can be prepared from fermentation of agricultural residues, is a non-toxic and renewable resource. So steam reforming of ethanol for hydrogen production has been paid more and more attention.In this thesis, various Ni, Fe, Cu and Co catalysts were prepared by impregnation method. Catalytic properties of the samples were evaluated in steam reforming of ethanol (SRE) 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 from La2(CO3)3 by calcinations method in air, bimetallic catalysts Ni-Fe/La2O2CO3 with different mole ratio of Ni and Fe and catalysts Ni/La2O2CO3, Cu/La2O2CO3 were prepared by impregnation method; The results showed that Ni-Fe/La2O2CO3 performed better than single catalyst (Ni/La2O2CO3,Fe/La2O2CO3) for SRE reaction, and higher selectivity of H2, Moreover, the stability of Ni-Fe/La2O2CO3 was better, which may be attribute to well dispersion of Ni and Fe on the surface of the supports, and the LaFexNi1-xO3 structure, which formed by Ni, Fe and La, could prevent from the agglomeration of nickel particles and solve the problem of coke deposition.In the second part, bimetallic catalysts Ni-Co/La2O2CO3 were prepared by impregnation method with different mole ratio of Ni and Co. The results showed that the catalyst with 1:1 mole ratio of Ni and Co performed better activity and selectivity for SRE reaction among the catalysts. The conversion of ethanol could reach 100% at 400℃; At 500℃, the selectivity of CO was the lowest about 0.28% and the selectivity of H2 was 93.77% on the catalysts, which was higher than single metallic catalysts (Ni/La2O2CO3 and Co/La2O2CO3). On steam reforming of ethanol (SRE), the capability of fracturing the C-C bond of Ni is higher than Co, but Co can improve the selectivity of H2. Therefore, the introduction of bimetallic catalysts Ni-Co improved the comprehensive abilities of the catalyst.In the third part, the support La2O2CO3 was modified by Ca and Zn. Ni/CaCO3-La2O2CO3 and Ni/ZnO-La2O2CO3 catalysts were prepared by impregnation method. The results showed that the catalysts with modified support performed better activity and selectivity. Ni/La2O2CO3 modified by Ca has good comprehensive abilities for ESR reaction. At 300℃, the conversion of ethanol was 81.8%, the selectivity of H2 was high as 92%, and the selectivity of CO was 2.3%.