Abstract:
A series of CeO
2-ZrO
2-MnO
x catalysts with different Mn contents (denoted as CZM
X, where
X is the molar fraction of MnO
x) were prepared by the redox precipitation method; the effect of Mn content on the catalytic performance of CZM
X in the oxidative degradation of toluene was then investigated. The results indicate that that the CZM
0.6 catalyst exhibits the best performance in toluene oxidation; a complete conversion of toluene can be achieved at 230℃. The XRD results suggest that the crystallinity of CZM
X decreases first, steps over the valley and then increases again with the increase of Mn content. From the H
2-TPR characterization, in contrast, a volcanic tendency is observed for the interaction among Ce-Zr-Mn. In particular, the CZM
0.6 catalyst displays poorest crystallinity and strongest Ce-Zr-Mn interaction, which can enhance the surface oxygen species. Meanwhile, the Raman and O
2-TPD results prove that the abundant oxygen vacancies on the catalyst surface can promote the migration of surface active oxygen species and then enhance the catalytic performance of CZM
X in toluene oxidation. In addition, the
in-situ DRIFTS results illustrate that the reaction of toluene oxidation over the CeO
2-ZrO
2-MnO
x catalysts proceeds via benzoic acid as the essential intermediate, which is rapidly converted to CO
2 and H
2O in the presence of O
2.