桥连结构对聚合物微球负载型TEMPO稳定性及催化氧化性能的影响

Effects of Bridge Structure on Stability and Catalytic Oxidation Performance of Polystyrene Microsphere Supported TEMPO

将2,2,6,6-四甲基哌啶氮氧自由基(TEMPO)通过醚键(-O-)和烷基咪唑(-(CH_2)n-im-)负载于交联聚苯乙烯微球上,分别制得PS-O-TEMPO、PS-im-C_4-TEMPO、PS-im-C_6-TEMPO和PS-im-C_(10)-TEMPO四种催化剂。采用傅立叶变换红外光谱仪(FT-IR)、元素分析仪(EA)、热重分析仪(TG)和激光粒度仪分别对催化剂的化学结构、热稳定性和溶液中的溶胀性能进行了表征。结果表明:与醚键负载相比,离子液体桥连可以使催化剂获得更高的TEMPO负载量;PS-im-C_6-TEMPO具有较高的热稳定性和较好的亲疏水性。将PS-im-C_6-TEMPO应用于序批式和固定床反应器中催化氧化苯甲醇,表现出较好的催化效果和稳定性。

Four catalysts(PS-O-TEMPO,PS-im-C4-TEMPO,PS-im-C6-TEMPO and PS-im-C10-TEMPO)were prepared by immobilization of2,2,6,6-tetramethylpiperidinooxy(TEMPO)on cross-linked polystyrenemicrospheres via-O-and-(CH2)n-im-bonds.Chemical structures of the resultant catalysts were confirmed byflourier transform infrared spectroscopy.TEMPO loadings were calculated from element analysis results,andthermal stabilities were measured with thermal gravimetric analyzer.The swelling capacities of themicrospheres were characterized with particle size analyzer.The results show that ionic liquid bridging resultsin higher TEMPO loading comparing to ether bonds.Moreover,PS-im-C6-TEMPO has better thermal stabilityand wettability,which exhibits good catalytic activity and stability when it is used in batch and fixed bedreactors for benzyl alcohol oxidation.