改性HZSM-5催化剂上苯与乙醇烷基化反应的研究

Alkylation of benzene with ethanol over modified HZSM-5

采用离子交换方法,用硫酸铁、硝酸镍、硫酸钛对HZSM-5分子筛进行改性,得到三种不同金属改性的催化剂;通过XRD、ICP、BET、NH3-TPD、Py-IR对催化剂进行了表征,并在连续流动固定床反应装置上进行了活性评价。相同方法改性后钛的负载量最大,酸性变化不大;铁负载量次之,弱酸和中强酸量增加;镍的负载量最少,酸强度降低最多,孔径最小。反应评价结果表明,改性后的催化剂同未改性的相比苯的转化率增加,乙苯选择性略有降低,乙苯产率增加,其中铁、钛改性后的分子筛乙醇利用率增加。综合考虑,铁和钛是比较合适的改性元素。

Alkylation of benzene with ethanol has been investigated over Fe,Ni,Ti ion exchanged modified HZSM-5 catalysts.The catalysts were characterized by NH3-TPD,Py-IR,XRD,BET,ICP.The Ti loading amount is the most and the Ni loading amount is the least.Modification of Ni enhanced the strong acid and depressed the moderate acid.After modified by Fe the weak and moderate acid increased and the strong acid decreased.With modification of Ti,the weak and moderate acid did not change significantly while the strong acid increased.The ratio of B acid and L acid of Ni-ZSM-5 decreased,the Fe-HZSM-5 and Ti-HZSM-5 increased.The pore diameter of and the BET surface area decreased after Fe and Ti modification.The reaction results showed that the ethylbenzene selectivity of the catalysts decreased a little after modification,while the ethylbenzene yield and benzene conversion increased.In conclusion,the Fe-HZSM-5 and Ti-HZSM-5 were the proper catalysts for the title reaction.