甲苯与叔丁醇在超稳Y沸石上的烷基化反应研究

Studies on Alkylation of Toluene with Tert-butyl Alcohol over USY Zeolite

考察了HM、USY、Hβ、HZSM-5等4种沸石分子筛在甲苯与叔丁醇烷基化反应中的催化性能,用NH3-TPD和Py-IR等手段对几种催化剂的物化性质进行了表征。结果表明,除催化剂的酸量外,催化剂的酸种类和孔结构也是影响催化性能的重要因素;L酸在甲苯的叔丁基化反应中起主要活性中心作用,且强酸中心的存在对烷基化产物的选择性不利。采用催化活性较高的超稳Y沸石分子筛作催化剂,考察了反应条件对烷基化反应的影响。在适宜的操作条件下,即催化剂焙烧温度623K、反应温度180℃、反应时间4h、初始压力0.6MPa和n(叔丁醇)/n(甲苯)为2时,甲苯转化率达46.4%,叔丁基甲苯(TBT)选择性为97.0%,对叔丁基甲苯(p-TBT)选择性为65.9%。

Catalytic performances of zeolite molecular sieves （ HM, USY, HI3 and HZSM-5） were investigated for the alkylation of toluene with tert-butyl alcohol in a 100 mL stainless steel batch reactor equipped with a stirrer, and the physical chemical properties of the above catalytic zeolites were characterized by ammonia program temperature desorption （NH3-TPD） and pyridine infrared spectroscopy （Py-IR） techniques. The results show that, besides the acid amount of catalyst, both the acid type and pore structure of the zeolites are the key factors influencing the catalytic behavior. The Lewis acid sites in catalyst mainly act as the active centers for the tert-butylation of toluene, and the strong acid sites do not favor the selectivity of target product. For the USY zeolite catalyst, which shows high catalytic conversion and selectivity, the influence of reaction conditions on tert-butylation of toluene were evaluated. The results show that the toluene conversion of 46.4%, the tert-butyltoluene （TBT） selectivity of 97.0% and the para-tert-butyltoluene （p-TBT） selectivity of 65.9% can be obtained by using the USY zeolite with calcination temperature 623 K as catalyst and under the suitable conditions as fallows： The reaction temperature and reaction time are 180℃ and 4 h, respectively, the initial pressure is 0,6 MPa, the molar ratio oftert-butyl alcohol to toluene is 2 and the cyclohexane is used as solvent.