An effective heterogeneous WO₃/TiO₂–SiO₂ catalyst for selective oxidation of cyclopentene to glutaraldehyde by H₂O₂

Abstract

TiO₂–SiO₂ mixed oxide with large pore size was synthesized by the xerogel method and it was then used to prepare the WO₃/TiO₂–SiO₂ catalyst by an incipient wetness method. The as‐prepared WO₃/TiO₂–SiO₂ sample was employed as the first heterogeneous catalyst in the liquid‐phase cyclopentene oxidation by aqueous H₂O₂, which exhibited higher selectivity (about 75%) to glutaraldehyde (GA) and, in turn, higher GA yield than the WO₃/SiO₂ heterogeneous catalyst and even the tungstic acid homogeneous catalyst under the same reaction conditions. The amorphous WO₃ phase was identified as the active sites and the loss of the active sites was proved to be not important. The lifetime of the catalyst was determined and its regeneration method was proposed. The effects of various factors on the catalytic behaviors, such as the WO₃ loading, the calcination temperature, the surface acidity and the reaction media, were investigated and discussed based on various characterizations including BET, XRD, XPS, FTIR, EXAFS and Raman spectra etc.