催化裂化过程中苯并噻吩的转化规律

在固定流化床装置上,采用USY-Cat和V-USY-Cat催化剂,考察了苯并噻吩与四氢萘以不同比例混合进料在催化剂作用下的转化路径和硫分布。结果表明,苯并噻吩在催化裂化过程中主要发生氢转移-裂化、缩合、烷基转移和歧化反应。纯苯并噻吩很难开环裂化脱硫,其气体硫、液体硫和焦炭硫的摩尔选择性分别为0.45%、49.71%和49.84%。四氢萘的加入改变了苯并噻吩反应路径的选择性,使气体硫的摩尔选择性略有增加,焦炭硫的摩尔选择性下降到3.18%。催化剂的酸性质对产物硫分布也有影响,酸密度越高,越有利于气体硫的生成;V的加入提高了USY-Cat催化剂的L酸/B酸比,使焦炭硫的选择性上升。

Research on Transformation of Benzothiophene Under FCC Condition

Reaction pathways and sulfur distributions of benzothiophene (BT) were investigated in a fixed fluid bed reactor with the mixture of BT and tetralin at different ratios as feed and USY-Cat and V-USY-Cat as catalyst. The results showed that the main reaction pathways of benzothiophene were hydrogen transfer-cracking, polymerization, alkylation and disproportionation under FCC condition. It was very difficult for pure benzothiophene to crack into H₂S, and the selectivity of sulfur products distributing in gas, liquid and coke were 0.45%,49.71% and 49.84%, respectively. Compared with pure benzothiophene, the selectivity for benzothiophene conversion to H₂S increased in the presence of tetralin, and the selectivity of sulfur in coke was reduced to 3.18%. Besides, the properties of catalyst also had great effect on the sulfur distribution in the cracking of BT, that is, the catalyst with high acid density could enhance the selectivity of H₂S, and vanadium increased L/B ratio of USY-Cat, thereby increasing the selectivity of sulfur in coke.