氢氛下萘异丙基化提高催化剂的活性

引言 萘异丙基化可得到2，6-二异丙基萘（2，6-diisopropylnaphthalene，简称2，6-DIPN），进一步空气氧化可制备2，6-萘二甲酸．后者是一种重要的高分子单体，用于合成高性能的热致性液晶高聚物和新一代聚酯聚萘二甲酸乙二酯（PEN）．与通用聚酯PET相比，PEN具有更好的物理机械性能、耐热性能、气体阻隔性能和抗紫外线辐射性能等．

Enhancement of catalyst activity in isopropylation of naphthalene in hydrogen atmosphere

Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene (2,6-DIPN) is a raw material for the production of advanced polyester materials such as PEN and liquid crystal polymers.In this study, the preparation of 2,6-DIPN through the isopropylation of industrial refined naphthalene with propylene was conducted in 0.5 L autoclave with steam dealuminated H-mordenite (SDHM) as the shape-selective catalyst instead of the conventional Friedel-Crafts catalysts and resulted in high selectivity and high yield of 2,6-DIPN.In order to slacken the deactivation of HM, the reaction was carried out in H2 atmosphere.The dehydrogenation of fused-ring polycyclics could be minimized and coke formation could be reduced.The preferred reaction conditions found were temperature of 275—300 ℃,hydrogen pressure of 0.4 MPa,reaction time of 7—8 h and 6%—7% of SDHM by mass,in which no side reactions were observed. From NH₃-TPD profiles,it could be seen that the relative strength of strong acid sites of SDHM in hydrogen isopropylation was greater than that in nitrogen isopropylation after the same reaction period.Comparing with the results obtained in nitrogen atmosphere, the conversion of refined naphthalene and yield of 2,6-DIPN could be remarkably increased to an average value as high as 90 % and 35 % respectively.Hence the catalytic activity of SDHM could be maintained for a longer time in H₂ atmosphere.