Preparation And Pyrolysis Gasoline Hydrogenation Property Of Catalysts With High Ni Dispersion Degree Prepared By Layered Precursor Methods

鈽匰upported metal catalysts were conventionally by impregnating active metal on different kinds of supports. But impregnation method commonly leads to a low metal dispersion on the surface of supports, because the big surface tension of impregnant solvent effect. Moreover the fine metal particles formed tended to sinter during the heating treatment at a high temperature. The layered double hydroxides (LDHs) are a group of anionic clays with layered structure, due to the crystal orientation effect different metal ions in the sheets and the static repulsion lie among the anions in the interlays will uniformly disperse. These materials can be used as precursor to make metal catalysts with high metal dispersion degree after calcinations and reduction.鈽匢n this paper, NiAl-LDHs have been synthesized on the surface of alumina carrier by chelated-ionization equation method. Ammonia is used as precipitator. The NiAl-LDHs/Al₂O₃ possesses higher specific area and narrower pore distribution. After calcination and reduction Ni/Al₂O₃ catalysts with high metal dispersion is formed. The surface metal dispersion degree can be mensurated by TPR and H₂-TPD technology. The results indicate the surface metal dispersion degree of this catalyst is higher than the catalyst prepared by conventional method. Low. temperature calcination is benefit to get high metal dispersion catalyst.鈽匩i/Al₂O₃ catalysts have been prepared using urea as the precipitator. The results indicate the surface metal dispersion degree of the catalyst prepared by this method is above 30%, much higher than the catalyst prepared by conventional method.鈽匱he catalysts prepared in this paper have been applied in the reaction of pyrolysis gasoline hydrogenation. Compared with the contrastive catalyst, these kind catalysts have higher reaction activity and selectivity.