不同分子筛催化乙苯与异丁烯液相烷基化反应制对叔丁基乙苯性能

Performances of differen zeolites catalyzed liquid-phase alkylation of ethylbenzene and isobutylene to p-tert-butylethylbenzene

关键化学品对叔丁基乙苯(p-TBEB)在工程塑料、高铁航空和电子信息等领域有广阔的应用前景。目前烷基化生产p-TBEB过程存在原料受限、催化剂失活快等弊端,同时也缺乏针对不同构型分子筛用于制备p-TBEB性能的系统研究。分别选取具有BEA、FAU、MOR、MWW和MTW拓扑结构的HBeta、HUSY、HMOR、HMCM-22和HZSM-12氢分子筛,采用XRD、SEM、NH3-TPD和N2物理吸/脱附对分子筛的结构和性质等进行了表征。结果表明,所选取的分子筛皆为纯相分子筛,具有各自典型的形貌和酸分布。在反应温度为200℃、反应压力为2.5 MPa、乙苯与异丁烯进料物质的量之比为4.0和异丁烯质量空速为1.0 h-1的反应条件下,系统研究了不同拓扑结构分子筛用于乙苯与异丁烯液相烷基化制备p-TBEB的催化性能。结果表明,酸量与分子筛的反应活性和目标产物选择性的关联度不高,孔道结构是影响其烷基化性能的关键因素。和其他几种分子筛相比,具有一维十二元环孔道的HZSM-12氢分子筛不仅能维持较高的乙苯转化率(≈20%),还具有高目标产物选择性,是最优的乙苯与异丁烯反应制p-TBEB的分子筛催化材料。

Key chemical p-tert-butylethylbenzene(p-TBEB)has broad application prospects in engineering plastics,high-speed rail aviation,electronic information and so on.At present,the process of producing p-TBEB through alkylation has drawbacks,such as limited raw materials and rapid catalyst deactivation.There is also a lack of systematic research on the performance of different molecular sieves with different configurations for the preparation of p-TBEB.HBeta,HUSY,HMOR,HMCM-22 and HZSM-12 hydrogen molecular sieves with BEA,FAU,MOR,MWW and MTW topological structures were selected,and their structures and properties were characterized by XRD,SEM,NH3-TPD and N2 physical adsorption/desorption.The results show that the selected molecular sieves are all pure phase molecular sieves with typical morphology and acid distribution.The catalytic performances of different topological structure molecular sieves for the liquid-phase alkylation of ethylbenzene and isobutylene to prepare p-TBEB was systematically studied under the reaction conditions of reaction temperature of 200℃,reaction pressure of 2.5 MPa,molar ratio of ethylbenzene to isobutylene feedstock of 4.0 and isobutylene mass space velocity of 1.0 h^(-1).The results show that the acid amount has a low correlation with the reaction activity and target product selectivity of the molecular sieve,and the pore structure is the key factor affecting its alkylation performance.Compared with several other molecular sieves,the HZSM-12 hydrogen molecular sieve with one-dimensional twelve-membered ring pores not only maintains a high ethylbenzene conversion rate(about 20%),but also has high target product selectivity,making it the most preferred molecular sieve catalytic material for the reaction of ethylbenzene and isobutylene to prepare p-TBEB.