MCM-41在微孔分子筛Y上的附晶生长

Overgrowth of mesoporous MCM-41 on zeolite Y

在采用传统的催化剂为载体的加氢精制工艺中,柴油馏分的深度加氢脱芳、脱硫依然是当今催化领域比较难以解决的问题之一.基于柴油中典型芳烃化合物和含硫化合物的分子尺寸,在第二段加氢工艺中,设计了具有介微复合孔分布的耐硫性催化剂载体.在微孔分子筛Y表面进行了MCM41的附晶生长,合成出了一种复合分子筛并利用各种表征手段对合成的样品进行了表征.结果表明,复合分子筛不同于同样条件下合成的纯MCM41和Y型分子筛的机械混合物.它具有介孔和微孔双重孔结构,而且复合分子筛中介孔相MCM41的孔壁中引入了Y型分子筛的次级结构单元,使孔壁厚度增大,改善了水热稳定性.

The deep hydrodearomatization and desulfurization of diesel fuel is a very challenging task by conventional hydrotreating processes using conventional catalyst support. Based on the molecular dimensions for typical aromatics and sulfur-containing compounds in diesel fuel, a pore structure design was proposed for sulfur-tolerant catalysts used in the second stage for aromatics reduction. A novel molecular sieve composite Y overgrown with a thin layer of mesoporous MCM-41 was prepared. The as-synthesized samples were characterized with various techniques. The results indicated that this composite was different from the mechanical mixture of MCM-41 and NaY. The composite possessed a mesopore system as well as a microporous structure of zeolite Y. Moreover, the mesopore wall of the composite was built of a lot of secondary building units characteristic of zeolite Y, which was quite different from the amorphous nature of MCM-41 in the mechanical mixture. The hydrothermal stability was improved.