关键词: 氧化镧助剂, 镍/二氧化硅催化剂, 间二硝基苯, 加氢, 间苯二胺

Abstract: A series of silica supported nickel catalysts promoted by lanthanumozide were prepared by using the incipient wetness co-impregnation and sequential impregnation methods.The effect of La₂O₃ introducing method on the activity and selectivity of Ni/SiO₂ catalyst for m-dinitrobenzene hydrogenation to m-phenylenediamine was studied,and the physical and chemical properties of the catalysts were investigated by the techniques of X-ray diffraction (XRD), temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS).The results showed that the addition sequence of La promoter played a substantial role in determining the catalytic hydrogenation properties of the nickel-based catalysts.When stepwise incipient impregnation method was used and La component was firstly impregnated on support before nickel component, the interaction between nickel and support was obviously weakened, the particle size of nickel crystallites was significantly reduced, and the nickel species were well dispersed, thus the activity of catalyst was apparently improved.In hydrogenation of m-dinitrobenzene under the conditions of hydrogen pressure 2.6 MPa, temperature 373 K and reaction time for 1 h, the conversion of m-dinitrobenzene and the yield of m-phenylenediamine on the above catalyst were up to 97.1% and 93.5%, respectively.The sample prepared by the La-Ni co-impregnation method also positively affected the catalytic performance of catalyst, but not as good as the former.When La component was impregnated after nickel component, however, the particle size of nickel crystallites increased apparently, thus resulting in dramatic decrease of catalyst activity.

Key words: 氧化镧助剂, 镍/二氧化硅催化剂, 间二硝基苯, 加氢, 间苯二胺