改性Y型分子筛上苯与多乙基苯的液相烷基转移

The Study of Liquid Phase Transalkylation of Benzene with Polyethylbenzene over the Modified Y Zeolite

为获得高性能的液相烷基转移反应催化剂,采用不同的方法对Y型分子筛进行改性处理。采用N_2吸附-脱附、程序升温脱附(NH_3-TPD)和吡啶吸附红外(Py-IR)等手段对样品进行了表征,并在连续微型固定床反应器中考察了改性Y型分子筛上苯和多乙基苯烷基转移反应的催化性能。结果表明,催化剂的烷基转移反应性能与Y型分子筛的孔道和B酸量有密切的关系。通过铵离子交换和酸处理改性均可以提高催化剂的B酸量、比表面积、孔容和孔径;水蒸汽处理会降低酸量;铵离子交换和酸处理复合改性的Y型分子筛催化性能最好。适宜的反应条件为:反应温度180~240℃,反应压力2.5~4.0 MPa,总物料重量空速3~5 h^(-1),苯与二乙苯的质量比2~4,在该条件下二乙苯转化率大于65%,乙基选择性大于98%。该催化剂性能稳定,1 000h运行后活性仍没有下降。

Modifications of Y zeolite by post treatment were carried out to prepare the high efficient catalyst for liquid-phase transalkylation.Y zeolites with different acidic properties and pore structures were characterized by N_2 adsorption-desorption,NH_3 temperature programmed desorption（NH3-TPD） and the Pyrdine（Py）-IR spectra.The catalytic performance of the modified Y zeolites was tested in the liquid-phase transalkylation reaction of benzene with polyethyl benzene in a continuous fixed-bed micro-reactor.The results showed that the catalytic performance has close relationship with the pore system and the amount of Brφnsted acid.The amount of Brφnsted acid can be improved by modifications of ammonium ion exchange and the acid treatment.It was found that the surface area,pore volume,average pore size and the steam treatment will reduce the amount of acid.The Y zeolite obtained by combined modifications of ammonium ion-exchange and acid treatment showed the best catalytic performance.The suitable reaction conditions for modified Y are as follows：reaction temperature 180-240℃,reaction pressure 2.5-4.0 MPa,weight hourly space velocity（WHSV） 3-5 h（-1） and the mass ratio of benzene to diethylbenzene 2-4.Under these conditions,the conversion of diethyl benzene was greater than 65%and the selectivity to the ethylated benzene was greater than 98%.No decline in the catalytic activity was observed after 1 000 hours run.