Pt／MeAPSO-11在正十二烷临氢异构化反应中的催化性能

CATALYTIC PERFORMANCE OF Pt/MeAPSO-11 IN THE HYDROISOMERIZATION OF n-DODECANE

采用水热法合成了Mg、Mn和Ni取代的不同Si含量的SAPO11分子筛，并采用XRD、XRF、SEM、NH3-TPD和TG／DTG手段进行了表征。担载Pt后，采用H2化学吸附法测定了Pt的金属性质，并测定了Pt／MeAPSO-11在正十二烷临氢异构化反应中的催化性能。结果表明，Mg、Mn和Ni引入SAPO—11分子筛的骨架，产生了新的酸性位，提高了SAPO-11分子筛的酸性。含不同金属原子的SAPO-11的酸性强弱顺序为：MgAPSO—11〉MnAPSO—11〉NiAPSO—11〉SAPO-11。在正十二烷临氢异构化反应中，Pt／MeAPSO-11表现出较高的活性和异构化选择性，但受MeAPSO—11的酸性和Pt的脱氢／加氢性能的作用，当Si含量较低时，各催化剂的活性顺序为：Pt／MgAPSO-11〉Pt／NiAPSO—11〉Pt／SAPO-11〉Pt／MnAPSO11；当Si含量较高时，其活性顺序为：Pt／SAPO—11〉Pt／NiAPSO-11≈Pt／MgAPSO—11〉Pt／MnAPSO—11。

Mg, Mn and Ni substituted SAPO-11 molecular sieves with different Si content were synthesized by hydrothermal method and characterized by XRD, XRF, SEM, NH3-TPD and TG/DTG. After loading with Pt, the metallic properties of Pt and catalytic performance of Pt/MeAPSO 11 catalysts were tested by H2 chemisorption and n-dodecane hydroisomerization, respectively. The results indicated that by substituting Mg, Mn and Ni into the framework of SAPO-11, some new acid sites on SAPO-11 were generated and the acidity of SAPO-11 was increased. The acid strength of MeAPSO- 11 decreased in the order of MgAPSO-11 〉 MnAPSO- 11 〉 NiAPSO-11 SAPO-11. In the hydroisomerization of n-dodecane, all Pt/MeAPSO-11s exhibited high activity and isomerization selectivity. However, controlled by the acidity of MeAPSO-11 and the （de）hydrogenation of Pt, the activity decreased following the order of Pt/MgAPSO-11 〉 Pt/NiAPSO-11 〉 Pt/SAPO-11 〉 Pt/MnAPSO-11 at low Si content, whereas, at high Si content, it decreased as follows.. Pt/SAPO-11 〉 Pt/NiAPSO-11 ≈ Pt/MgAPSO-11 Pt/MnAPSO-11.