稀土和磷改性对裂化催化剂反应性能的影响

我们采用稀土以及稀土和磷两种方式对Y型沸石表面进行修饰，NH3-TPD测试表明稀土和磷复合改性Y沸石(P—RE—USY)的酸性分布更集中在中强酸范围．在固定床和提升管装置上评价了含有P—RE-USY沸石催化剂的反应性能．经过稀土和磷复合改性，增强了沸石孔道的酸性中心，而表面活性中心在磷和稀土相互作用的改性中得以减少和弱化．这种修饰作用引导更多的烃分子进入沸石孔道中进行反应，减少了烃分子通过表面反应形成大量烯烃分子的几率．同时，由于烯烃的降低不完全来自二次氢转移反应的饱和过程，所以，适度降低二次反应有效地减少了中间馏分油的裂解，提高了柴油收率．

Effect of Modification through Rare Earth and Phosphorus on the Reaction Performance of Cracking Catalyst

Zeolite Y modified through rare earth alone or rare earth and phosphorus together was studied. The NH_3-TPD analysis showed that the acid distribution of P-RE-USY (zeolite Y modified with rare earth and phosphorus) is more concentrated on the range of intermediate and strong acidity. The P-RE-USY catalyst as an active component was evaluated in the small confined fluidized bed and pilot riser reactor. After modification with rare earth and phosphorus, the acidity density and strength in the pores of zeolite Y are improved effectively and the surface acidity is reduced and weakened suitably owing to the interaction of rare earth cation and phosphate anion. This kind of modification can direct more hydrocarbons to enter into the pores to be converted and remarkably reduced the possibility of naphtha olefins forming through surface cracking reaction. In addition, because naphtha olefin reduction doesn't depend on olefin saturation through secondary hydrogen transfer reaction completely, this kind of reaction mode can decrease the excessive cracking of mediate distillate and improves the diesel oil yield effectively.