ZSM-5分子筛催化苯基羟胺制对氨基苯酚性能考察

采用水热合成法制备了Na-ZSM-5，经离子交换制得H-ZSM-5(n(Si)/n(Al)=40)分子筛，并用其催化苯基羟胺Bamberger重排制对氨基苯酚。采用XRD、FT-IR、N₂吸附、SEM和Py-FTTR表征技术，研究了分子筛的物化性质。结果表明，自制的分子筛是结晶性良好的MFI结构微孔分子筛。Na-ZSM-5分子筛骨架中几乎无B酸，H-ZSM-5(40)分子筛存在微量的B酸和L酸中心。结果表明，H-ZSM-5(40)分子筛作酸催化剂，尽管苯基羟胺的转化率较低，但对氨基苯酚的选择性和收率分别高达72.48%和58.75%。通过优化获得的最佳催化反应条件：反应温度353 K，反应时间2 h，水作溶剂，苯基羟胺与催化剂的质量比为1∶3，苯基羟胺的转化率可高达86.35%，对氨基苯酚的选择性高达78.33%。

Preparation of p-Aminophenol from Phenyl-Hydroxylamine Catalyzed by ZSM-5 Zeolites

Na-ZSM-5 was prepared by in-situ hydrothermal process. H-ZSM-5 (n(Si)/n(Al)=40) molecular sieves were prepared by ion exchange. p-Aminophenol was prepared by Bamberger rearrangement catalyzed by the molecular sieves using phenyl-hydroxylamine as raw material. XRD, FT-IR, N₂ adsorption-desorption, SEM and Py-FTIR techniques were used to study the topological structure, micropore pore size and acidity of Na-ZSM-5 and H-ZSM-5 molecular sieves. The results showed that the prepared molecular sieves had MFI microporous structures with well crystallinity. Py-FTIR technique showed that Na-ZSM-5 had almost no B acid. H-ZSM-5(40) molecular sieve had weaker B acid and L acid. Catalysis performance showed that phenyl-hydroxylamine conversion was low in the presence of ZSM-5 with weaker acidity as catalyst. However, because of its moderate pore size, p-aminophenol selectivity and yield reached as high as 72.48% and 58.75%, respectively. The optimal conditions of p-aminophenol preparation from phenyl-hydroxylamine Bamberger rearrangement were as follows: mass ratio 1∶3 of phenyl-hydroxylamine to H-ZSM-5(40) molecular sieve, optimal reaction temperature of 353 K, optimal reaction time of 2 h, and water as solvent. Phenyl-hydroxylamine conversion and p-aminophenol selectivity were as high as 86.35% and 78.33%, respectively.