A series of Ce‐Mn‐Ox catalysts synthesized under different hydrothermal conditions were evaluated by catalytic removal of toluene. The results of characterization showed that the contents of oxygen vacancies and active species in catalysts were crucial for the catalytic oxidation process. The concentration of Ce3+, Mn3+, and adsorbed oxygen associated with structural defects in Ce‐Mn‐Ox catalysts could be controlled by hydrothermal conditions, which were considered to promote redox capacity and improve catalytic oxidation performance. In addition, suitable synthetic conditions could increase the SBET and Vp of catalysts. Among the prepared catalysts, CM‐100 showed the best catalytic performance due to the generation of more defective oxygen and active species (Ce3+, Mn3+, and surface‐adsorbed oxygen). In addition, the CM‐100 catalyst showed satisfactory water resistance and stability.

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Manganese oxide catalysts are considered to be active in the catalytic purification of volatile organic compounds based on two theories. According to one view, defects are mainly constructed to increase the amount of adsorbed oxygen and, consequently, the catalytic activity, whereas the opposite view suggests that the mobility of lattice oxygen is the main reason for determining the catalytic performance. In order to investigate which form of oxygen is the key factor controlling the catalytic performance of manganese oxides, a series of manganese oxide octahedral molecular sieves (OMS‐2) with different adsorption and lattice oxygen properties were synthesized in this study, and the catalytic oxidation performance of the catalysts for toluene was examined. The impact of various oxygen species on the catalytic activity of OMS‐2 was investigated in depth by characterization by Raman, X‐ray diffraction, scanning electron microscope, Brunauer–Emmett–Teller, O2 temperature‐programmed desorption, H2 temperature‐programmed reduction, X‐ray photoelectron spectroscopy, and so forth. It was discovered that OMS‐2‐150 exhibits excellent catalytic activity for toluene purification due to its higher Mn4+ and lattice oxygen as well as low‐temperature reducibility. In addition, in situ diffuse reflectance, infrared Fourier transform spectroscopy also verified that lattice oxygen dominates the reaction and improves the catalytic performance. As such, in contrast to previous investigations, this study found that lattice oxygen migration was more important than adsorbed oxygen content for manganese oxides in the field of volatile organic compounds purification. This brings a new perspective to the preparation of manganese‐based catalysts with promising catalytic behaviors.

The CeO2 modified by silicotungstic acid (impregnation method [SiW/CeO2] and one pot method [CeO2‐Si‐W]) was investigated in the NH3‐SCR reaction. The surface nitrate species and surface acid sites were improved by the introduction of silicotungstic acid into CeO2, which stopped forming stable nitrate, and then improved the N2 selectivity. The interaction between Ce and W species existed and caused the formation of Ce2(WO4)3 at CeO2‐Si‐W, resulting in the abundance of unsaturated W=O, which contributed to the generation of Brønsted acid sites and was responsible for the superior SCR performance. Thus, CeO2‐Si‐W exhibited the best NOx conversion and nearly 100% NOx conversion was obtained at 225–450°C.