Abstract:

The effects of amino acid-citric acid modification on Y zeolite crystal form, pore structure, acidity and microstructure were investigated. Unsupported hydrocracking catalyst was prepared by pretreatment of Ni-W unsupported active phase with the modified Y molecular sieve. The reaction performance of the catalyst was investigated in a fixed bed hydrogenation unit using straight-run diesel as raw material. The results showed that the modified molecular sieves with better crystal retention, lower total acid content, slightly increased the B acid and L acid ratio and abundant pit structure on the surface could be obtained by the combined modification of amino acid and citric acid. The modified molecular sieves could be applied to the preparation of unsupported hydrocracking catalyst, which was beneficial to the interactions of unsupported active phase particles and the acid center on the surface of molecular sieves. In the process of converting straight-run diesel oil in a refinery, the prepared catalyst showed better hydrogenation saturation and ring-opening performance, and was more beneficial to obtaining diesel fractions with low BMCI value, providing high-quality raw materials for steam cracking units.

Key words: molecular sieves, modification, catalyst, hydrogenation, cracking

摘要：

以环境友好的氨基酸和柠檬酸作为Y分子筛改性试剂，考察了氨基酸-柠檬酸组合改性方法对于Y分子筛晶型、孔结构、酸性以及微观形貌的影响；将Ni-W非负载活性相与改性分子筛预处理后制备非负载型加氢裂化催化剂，以直馏柴油为原料，用固定床加氢装置进行反应性能考察。结果表明，氨基酸-柠檬酸组合改性方法可以得到晶型保留较好、总酸量降低、B酸与L酸比值略有增加、表面具有丰富坑孔结构的改性Y分子筛，应用于非负载型加氢裂化催化剂制备，有利于非负载活性相粒子与分子筛表面酸中心的结合，所制备催化剂在转化某炼厂直馏柴油的过程中，表现出了较好的加氢开环性能，更有利于获得低芳烃指数（BMCI）的柴油馏分，为蒸汽裂解装置提供优质原料。

关键词: 分子筛, 改性, 催化剂, 加氢, 裂化