The gelation rate of LaMnO3 colloid was successfully modulated by introducing trace of tartaric acid and nitric acid simultaneously to construct 3DOM LaMnO3. To enhance surface oxygen vacancies, Fe, Zn, Cu and Co metal oxides were introduced on the surface of 3DOM LaMnO3 to modulate their surface composition, respectively. The morphology, crystalline, composition and reducibility of the prepared catalysts were characterized by SEM, XRD, XPS and TPR, respectively. The results showed that the surface oxygen defects can be enhanced distinctly with the introduction of metal oxides. Among the four metal oxides modified LaMnO3, the Co/LaMnO3 sample exhibited highest oxygen defects content and lowest reduction temperature. The catalytic properties of the five samples follow as the order: LaMnO3 < Fe/LaMnO3 < Zn/LaMnO3 ≈ Cu/LaMnO3 < Co/LaMnO3, which is consisted with that of their surface oxygen vacancies content, indicating that oxygen vacancies content is a crucial factor on catalytic oxidation of ethyl acetate.
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This work is supported by National Nature Science Foundation of China (51572004, 21504001), Natural Science Foundation of the Higher Education Institutions of Anhui Province, China (KJ2016SD06), Natural Science Fund for Distinguished Young Scholars from Anhui Polytechnic University (2016JQ01), and Top-notch Talent Cultivation Plan from Anhui Polytechnic University (2016BJRC002).