苯异丙基化反应条件对β沸石失活的影响

EFFECT OF REACTION CONDITIONS ON DEACTIVATION OF ZEOLITE β FOR BENZENE PROPYLATION

改性 β沸石是液相合成异丙苯的高效催化剂。根据中试催化剂的失活机理 ,设计了实验室条件下催化剂的催速失活反应。采用UV Vis、13 CNMR表征中试失活催化剂上的沉积物 ,考察了温度、进料苯烯摩尔比、总质量空速及反应时间对催化剂失活的影响。结果表明 ,反应温度对积炭的影响最为敏感 ,随着反应温度的升高 ,多烷基化和稠环化副反应的几率增加 ,催化剂上沉积物的稠环化加重。在相同的温度下 ,随着进料中苯烯摩尔比的减小 ,多烷基化和稠环化沉积物的生成量增加。在催化剂可承载范围内 (总质量空速小于 2 0h-1) ,空速对沉积物组成和生成量的影响不大。随着反应时间的延长 ,沉积物的生成速率减小。

Modified zeolite β showed remarkable performance as a catalyst for benzene propylation in liquid phase. The zeolite catalyst was deactivated after 8000 h operation in pilot-plant scale, and the formed carbonaceous deposit was examined by 13 C NMR and UV-Vis. The accelerated decay was designed to investigate the effect of reaction conditions (temperature, the ratio of benzene to propene, MHSV and time on stream) on coke deposition for pilot-plant deactivated catalysts and/or accelerating decayed catalysts, and comparative characterization was carried out. Results showed that reaction temperature played a crucial role to the nature of the deposit and further reaction of the products was expedited with the increase of the reaction temperature. The ratio of benzene to propene was another factor relating to the total amount of the deposit on catalyst, while space velocity showed no obvious effects. The longer the time on stream, the lower the rate of further coke formation was observed.