催化柴油加氢裂化催化剂积炭形态及成因探讨

Characterization and Formation of Coke in Hydrocracking Catalyst for Light Cycle Oil

采用小型固定床加氢装置和Ni-Mo型加氢裂化催化剂进行催化裂化柴油(LCO)加氢裂化反应,采用TG-MS、GC-MS、13 C NMR和元素分析手段研究了催化剂积炭的类型和组成,并探讨了积炭的形成原因。结果表明,根据积炭燃烧的难易程度,催化剂积炭分为3种类型。积炭为缩合程度较高的稠环芳烃,侧链较少,且以短侧链为主。积炭中难溶性积炭较多,可溶性积炭主要为芘及其同系物和晕苯及其同系物,并含有少量氮杂环化合物。积炭前身物主要为芳烃,而LCO中芳烃含量过高以及较高的反应温度、低的氢分压是LCO加氢裂化过程催化剂积炭形成的主要原因。

A small fixed-bed hydroprocessing bench unit and Ni-Mo hydrocracking catalyst were used for light cycle oil hydrocracking,and then the species and composition of the coke in catalyst were characterized by thermal gravity-mass,gas chromatography-mass spectroscopy,solid ^（13）C nuclear magnetic resonance and elemental analysis.The coke formation was discussed.Results showed that the coke could be simplified in three types based on their combustion temperatures.Coke was mainly composed of polycyclic aromatics with a few short side chains and high degree of condensation.In the coke the amount of insoluble coke was more than the amount of soluble coke which mainly consisted of pyrene,coronene and their homologs and a few of nitrogen heterocyclic compounds.The aromatics in feedstock were considered as coke precursor,so more amount aromatics plus high temperature and low hydrogen pressure were the main causes of coke formation during the LCO hydrocracking.