催化裂化轻循环油生产轻质芳烃的分子水平研究

从分子水平研究了催化裂化轻循环油（LCO）经加氢处理后进行催化裂化生成苯、甲苯、二甲苯和乙苯等轻质芳烃（BTXE）的反应规律。认为加氢LCO中重质单环芳烃（包括烷基苯和环烃基苯）的含量及催化裂化反应条件是影响轻质芳烃产率的关键，适宜的加氢处理深度(加氢LCO氢质量分数为11.00%)、催化裂化较高的反应温度（大于550 ℃）和较大的剂油比（大于8）有利于生产轻质芳烃。在实验条件范围内，LCO中环烃基苯的表观裂化反应比例大于73.4%，表观缩合反应比例小于14.7%，表观未转化比例小于15.0%，且高温有利于LCO中环烃基苯的裂化反应。加氢LCO经催化裂化反应生成轻质芳烃的单程产率可达14.3%，约占催化裂化产物中单环芳烃总量的1/3。

MOLECULAR-BASED STUDY ON FCC LCO TO LIGHT AROMATICS

The reaction rule on production of light aromatics (BTXE) of benzene, toluene, xylene and ethylbenzene from hydrotreated LCO by FCC process is studied on molecular level. The results show that the content of heavy monocylic aromatics and FCC reaction conditions are the key factors which influences the yield of BTXE and that the optimal reaction conditions for converting LCO to light aromatics are: moderate hydrotreating severity (hydrogen content 11.0% in hydrotreated LCO), high reaction temperature (over 550 ℃) and middle ratio of catalyst to oil (more than 8) of FCC process. In the range of experimental conditions, the proportion of the apparent cracking reaction of monocyclic aromatic hydrocarbons in hydrotreated LCO is above 73.4%, the condensation reaction is less than 14.7%, and the rest is unconverted monocyclic aromatics. Increasing FCC reaction temperature is favorable for monocyclic aromatics cracking. The once-through yield of light aromatics reaches 14.3% under experimental conditions, about 1/3 of all monocyclic aromatic hydrocarbons in FCC products. It is concluded that the integration of hydrogenation and FCC process is a cost-effective technology to convert inferior LCO to high value BTXE light aromatics.