离子液体桥连的聚苯乙烯负载型2,2,6,6-四甲基哌啶氧化物催化剂的稳定性

Stability of the catalyst obtained by covalently immobilization of 2,2,6,6-tetramethylpiperidine-1-oxyl on the polymer surface through ionic liquid linkage

研究将小分子催化剂2,2,6,6-四甲基哌啶氧化物通过化学共价键键合离子液体桥连的方法负载在聚苯乙烯氯球上,制备负载型催化剂。考察其在N2气氛的热稳定性、溶剂中的溶胀性以及两相反应体系(NaClO/NaBr、CH2Cl2/H2O)中的化学稳定性。结果表明,负载型催化剂在反应温度低于180℃表现出较好的热稳定性,且在苯甲醇催化氧化过程中可以循环使用20次,苯甲醇转化率大于95%。所得催化剂具有亲水亲油的两亲性,适用于两相体系的催化环境,比直接负载2,2,6,6-四甲基哌啶氧化物的催化剂有更好的耐溶剂性及稳定性。

PS-IL-TEMPO catalyst was prepared by covalently immobilizing the small molecular catalyst 2,2,6,6-tetramethylpiperidine-l-oxyl （TEMPO） through ionic liquid linkage on the surface of the chlo- romethylated polystyrene beads （PS-C1）. And its thermal stabilities in nitrogen atmosphere, swelling behaviors in the solvents, and chemical stabilities in a biphasie oxidation system （NaClO/NaBr, CH2Cl2/H2O） were investigated. The results showed that the catalyst for catalytic oxidation of benzene methanol exhibited good thermostability at reaction temperature below 180 ℃, and could be reused for 20 consecutive recycles with benzene methanol conversion of more than 95%. The catalyst with amphiphilic properties of hydrophilicity and hydrophobicity was suitable for biphasic oxidation surrounding, and had better solvent resistance and stability than the catalyst directly loaded with 2,2,6,6-tetramethylpiperidine-1-oxyl.