摘要
以正硅酸乙酯为硅源 ,通过原位溶胶 -凝胶技术 ,将全氟磺酸树脂NafionNR5 0 (简称NR5 0 )颗粒分散组装到多孔性SiO2 中 ,制得中孔孔道、NR5 0纳米颗粒分布均匀的固体酸催化剂Nafion/SiO2 ,增加NR5 0的有效比表面积和酸性中心的暴露量 ,提高其酸性中心的可接近程度。在非极性溶剂异丙苯中 ,催化剂Nafion/SiO2 对α -甲基苯乙烯的二聚反应具有高催化活性和选择性 ,其单位酸性中心的催化活性比NR5 0高 2～ 3个数量级 ;α -甲基苯乙烯的二聚反应为一级反应。
Nafion NR50 resin has been used as a heterogeneous strong acid catalyst for a range of acid-catalyzed reactions;however,the activity is limited in non-polar solvents or for gas phase reactions due to the extremely low surface area.In this paper,a novel solid acid catalyst Nafion/SiO 2 with meso-pore was prepared using an in-situ sol-gel technique wherein solutions of Nafion resin were mixed with soluble silicon sources of tetraethylorthosilicate to form a gel.Nafion resin nano-particles were completely trapped and highly dispersed within a porous silica network.In the batch reactor,the dimerization of α-methylstyrene catalyzed by these solid acid catalysts was examined at 50 ℃ and atmosphere pressure in non-polar solvent cumene.These new porous materials exhibited significantly enhanced activity for the dimerization of α-methylstyrene due to the increased accessibility of the Nafion resin-based acid sites,and activity enhancements of 2～3 orders of magnitude (per unit acid site of Nafion resin) relative to the pure Nafion NR50 were observed.Simultaneously,first-order rate constants for the dimerization of α-methylstyrene catalyzed by these catalysts were also determined.
出处
《石油化工》
CAS
CSCD
北大核心
2002年第6期427-430,共4页
Petrochemical Technology
