Controlled immobilization of methyltrioxorhenium(VII) based on SI-ATRP of 4-vinyl pyridine from halloysite nanotubes for epoxidation of soybean oil

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• 作者：Junqing Jiang^a ; ^b ; Yanwu Zhang^b ; Danhua Cao^b ; Pingkai Jiang^a ; ^{pkjiang@sjtu.edu.cn}
• 关键词：Controlled immobilization ; Methyltrioxorhenium ; Halloysite nanotubes ; SI-ATRP graft polymerization ; Epoxidation ; Soybean oil
• 刊名：Chemical Engineering Journal
• 出版年：2013
• 出版时间：15 January, 2013
• 年：2013
• 卷：215-216
• 期：Complete
• 页码：222-226
• 全文大小：580 K

文摘

Poly(4-vinylpyridine) (P-4VP) brushes of different lengths were grafted onto halloysite nanotubes (HNTs) by surface-initiated atom transfer radical polymerization (SI-ATRP) and methyltrioxorhenium(VII) (CH₃ReO₃, MTO) was immobilized onto HNTs through P-4VP brushes to catalyze epoxidation of soybean oil. 2-Bromoisobutyryl bromine was chosen as the initiator of SI-ATRP and anchored by reacting with hydroxyl groups of HNTs. To reduce the effect of 4-vinylpyridine on the initiator, Me₆tren as the ligand was introduced into the polymerization. The length of P-4VP brushes was controlled by the polymerization time. Through coordination between N in pyridine rings and MTO, a novel heterogeneous catalyst with different loadings of MTO for epoxidation of soybean oil was prepared. FTIR, TGA, TEM, GPC, UV-visible absorption spectroscopy and ¹H NMR were used to characterize HNTs with P-4VP brushes and the heterogeneous catalysts. The results indicated that the length of P-4VP brushes increased with the polymerization time and MTO loading increased with P-4VP brush length. MTO molecules dispersed uniformly in P-4VP brushes and the heterogeneous MTO combined with H₂O₂ had good catalytic activity and selectivity to epoxidation of soybean oil. TOF of heterogeneous MTO increased with MTO loading and no ring-opening reaction occurred during epoxidation.