Co(Ⅲ)官能化SBA-15的制备、表征及其催化环己烯环氧化

摘要

通过环戊二烯基修饰的SBA-15(SBA-15-Cp)与马来酸酐的Diels-Alder反应及水解合成了邻二羧酸官能化的SBA-15,并将原位生成的Co(Ⅲ)络合物负载于其上制得Co(Ⅲ)官能化SBA-15样品SBA-15-Co(Ⅲ).傅里叶变换红外光谱、元素分析和X射线光电子能谱法结果证实羧酸官能团和Co(Ⅲ)成功地引入到介孔材料中.X射线粉末衍射、N2物理吸附-脱附和高分辨透射电镜等表征结果表明,在制备过程中,材料仍较好地保持SBA-15的孔结构.以异丁醛为牺牲剂,乙腈为溶剂,氧气流速5 ml/min,在40℃反应6 h时,SBA-15-Co(Ⅲ)在环己烯环氧化反应中表现出较高的活性和稳定性,环氧环己烷产率和选择性分别达58%和63.7%,且经过6次循环后,仍分别可达51.6%和56.5%.%A Co(Ⅲ)-modified mesoporous material (SBA-15-Co(Ⅲ)) was prepared by supporting an in situ formed Co(Ⅲ) complex on o-dicarboxylic acid modified SBA-I5 (SBA-15-(COOH)2) that was synthesized by first the Diels-Alder reaction between maleic anhydride and cyclopentadienyl-modified SBA-15 (SBA-15-Cp) and then the hydrolysis of resulting anhydride. Fourier transform infrared spectroscopy, elemental analysis (ICP-AES), and X-ray photoelectron spectroscopy confirmed the successful incorporation of carboxyl and Co(Ⅲ) in the mesopores. The results of X-ray powder diffraction, N2-sorption, and high resolution transmission electron microscopy showed that SBA-I5-Co(Ⅲ) well maintained the mesostructure of SBA-15. In the presence of isobutyraldehyde, SBA-I5-Co(Ⅲ) showed moderate activity and stability in the epoxidation of cyclohexene when the flow rate of O2 was 5 ml/min. the solvent was acetonitrile. the reaction temperature was 40 ℃, and time was 6 h. The yield and selectivity of cyclohexene oxide could reach 58％ and 63.7％, respectively. The yield and selectivity of cyclohexene oxide could still maintained 5 1.6％ and 56.5％ after six catalytic cycles.