Preparation of Immobilized Chromium Schiff Base Complexes and Their Catalytic Performance for Cyclohexene Epoxidation

Abstract

Three typical amino acid Schiff base chromium(III) complexes immobilized on MCM-41 were prepared and characterized by various physico-chemical methods such as Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray powder diffraction, N 2 sorption, and elemental analysis. The obtained immobilized complexes were effective catalysts for the epoxidation of cyclohexene with 30% hydrogen peroxide and they exhibited significantly enhanced catalytic performance compared with their corresponding homogeneous analogues. Under optimal reaction conditions the highest conversion of cyclohexene was 52.6% with 73.5% epoxide selectivity. In addition, the catalytic activity was retained after recycling 6 times. 将 3 种典型的氨基酸-水杨醛 Schiff 碱铬 (III) 配合物固载于介孔 MCM-41 上, 制得非均相 Schiff 碱铬配合物, 用傅里叶变换红外光谱、紫外-可见光谱、X 射线固体粉末衍射、N 2 吸附和元素分析对其结构进行了表征, 并以 30% H 2 O 2 为氧化剂, 考察该配合物对环己烯环氧化反应的催化性能. 结果表明, 均相配合物非均相化后, 其催化活性明显提高. 在较优的反应条件下, 环己烯转化率可达 52.6%, 环氧环己烷选择性为 73.5%, 且该非均相催化剂重复使用 6 次后, 仍保持较高的催化活性. Three promising immobilized complexes were prepared for the epoxidation of cyclohexene. The highest cyclohexene conversion was 52.6% with 73.5% epoxide selectivity. Moreover, catalytic activity was retained after 6 runs.