Nanorods （NR） and nanoparticles （NP） of ceria were prepared by hydrothermal synthesis method and used as catalyst support to load cobalt for steam reforming of ethanol （SRE）. The catalysts were characterized by using temperature programmed reduction, X-ray diffraction, transmission electron microscopy and thermal analysis techniques. CeO2 NP had relatively smaller particle size and larger surface area, and CeO2 NR could form more oxygen vacancies. For SRE reaction, Co/CeO2 NP was more active and exhibited a little better anti-sintering ability, while Co/CeO2 NR showed obviously better anti-carbon deposition ability. The larger surface area and higher dispersion of cobalt oxide resulted in the higher activity for Co/CeO2 NP catalyst. Meanwhile, the stronger interaction between cobalt species and ceria was attributed to the better anti-sintering ability for Co/CeO2 NP. The improvement of the anti-carbon deposition for Co/CeO2 NR was owing to the generation of oxygen vacancies from the ceria nanorods.
LaFeO3 perovskite supported Ni and Ni-Fe catalysts were prepared and applied to methanation reaction of syngas. Two preparation methods were employed. One was one-step citrate complexing method, and the other was a two step method using citrate complexing method to produce LaFeO3 and followed by loading nickel oxide on it with impregnation. The structure evolution of the sample as prepared was investigated by XRD, TPR and TEM techniques. For the former, the chemical composites of the calcined sample are NiO-Fe2O3/LaFe1-xNixO3. After reduction and reaction of CO methanation, its composites convert to Fe-Ni@Ni/LaFeO3-La2O2CO3, in which Fe-Ni@Ni is metal particles in nano-size composed of nickel core and Fe-Ni alloy shell. For the latter, the chemical composites of the calcined sample are NiO/LaFeO3; and after reduction and reaction of CO methanation, its chemical composites change to Ni/LaFeO3. Ni/LaFeO3 catalyst is a little more active, while Fe-Ni@Ni/LaFeO3-La2O2CO3 is much more stable and shows very good resistance to carbon deposition. In this work it is aimed to show that the structure and composites of the catalysts can be tailored using perovskite-type oxide as precursor with different preparing method or preparing condition. Therefore, it is a promising route to prepare supported bi-metal catalysts in nano-size for a lot of metals with desired catalytic performances.
NiO/Ce0.7Pr0.3O2 catalysts were prepared by co-precipitation method and used for steam reforming of ethanol to produce hydrogen. The influence of nickel content and the doping of Pr on the catalytic performance were investigated. The catalysts were characterized by using temperature programmed reduction （TPR）, X-ray diffraction （XRD） and thermal analysis techniques. 15 wt.%NiO/Ce0.7Pr0.3O2 catalyst was highly active and selective for steam reforming of ethanol to produce hydrogen. With the doping of Pr, the anti-carbon deposition property of the catalyst and the anti-sintering stability of metal nickel were effectively improved. The improvement of the anti-carbon deposition is attributed to generation of oxygen vacancies resulted from the Pr doping; while the improvement of anti sintering is ascribed to the intensified interaction between the nickel species and the support which is owing to the Pr-doping resulted incorporation of some nickel ions into ceria lattice.
