加氢处理催化剂的制备和表征Ⅰ.MoNiP/Al_2O_3催化剂的制备及助剂的作用

Preparation and Characterization of Hydrotreating CatalystsⅠ. Preparation of MoNiP/Al_2O_3 and Effect of Promoters

采用专利方法制备出一种新型的γ Al2 O3 ,并以其为载体 ,制备出加氢处理催化剂MoNiP/Al2 O3 .用PAS CA ,XPS ,DRS ,TPR和微型反应色谱等技术对γ Al2 O3 和催化剂进行了表征 ,考察了Ni和P两种助剂的作用 .结果表明 ,γ Al2 O3 具有较大的孔径 ,集中的孔分布和较高的机械强度 ;活性金属Mo在γ Al2 O3 表面上的化学分散量(分散阈值 )可达 5 0 4～ 5 82 μmol/m2 .因而特别适合用作高活性加氢处理催化剂的载体 .引入的Ni主要是同Mo/Al2 O3 催化剂表面上较稳定的金属 载体相互作用复合物反应 ,并生成类NiMoO4 化合物 ;在MoNi/Al2 O3 催化剂中引入P ,有利于抑制四面体配位结构的物种Mo[T],增加八面体配位结构的物种Mo[O],改善催化剂的还原性能 ,从而提高催化剂的加氢处理活性 .助剂Ni和P的最佳含量分别为w(Ni) =4 0 %和w(P) =2 6 % .

Based on the characterization of a series of commercial γ Al 2O 3, a new type of γ Al 2O 3 has been developed. The γ Al 2O 3 has larger CDA for active metal (such as Mo or W) from 5 04 to 5 82 μmol/m 2, and also has larger pore diameter, concentrated pore volume distribution and higher mechanical strength, so it can be used as a good support for hydrotreating catalysts. The MoNiP/Al 2O 3 catalyst has been prepared and the effect of promoters Ni and P was studied by means of PASCA in conjunction with XPS, DRS, TPR and microreaction chromatography. The results showed that the promoter Ni combined with 2 types of stronger metal support interaction centers, resulting in formation of NiMoO 4 like compound. The optimum Ni content is w (NiO)=4 0% ( n (Ni)/ n (Mo)=0 323) in the catalyst. The promoter P plays a role in inhibiting the formation of tetrahedral structure Mo[T] and in promoting the formation of octahedral structure Mo[O]. The optimum P content is w (P)=2 6% ( n (P)/ n (Mo)=0 084) in the catalyst.