Selective oxidation of cyclopentene to glutaraldehyde by H2O2 over Nb-SBA-15

Abstract

A series of niobium-containing mesoporous materials Nb-SBA-15 have been prepared by a sonication–impregnation and hydrothermal process. The dispersion and structural properties of the niobium-containing species were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, temperature programmed desorption and N₂ adsorption–desorption. Their catalytic performance was evaluated for the selective oxidation of cyclopentene (CPE) to glutaraldehyde (GA). The novel Nb-based catalyst exhibited high activity with a CPE conversion of 87.3% and GA yield of 62% under favourable conditions. No significant deterioration of the catalyst performance was found in the cycle test, indicating the stability of the catalyst. The new Nb-SBA-15 catalyst displayed good catalytic performance both in ethanol and tert-butyl alcohol, which made the catalytic reaction system more flexible for future application. In addition, in situ infrared spectroscopy was adopted to monitor the reaction process. A mechanism of CPE oxidation to GA was proposed tentatively according to our experiment and some reports in the literature.