Roles of Oxygen Vacancies in the Bulk and Surface of CeO₂ for Toluene Catalytic Combustion

Abstract

Catalytic combustion technology is one of the effective methods to remove VOCs such as toluene from industrial emissions. The decomposition of an aromatic ring via catalyst oxygen vacancies is usually the rate-determining step of toluene oxidation into CO2. Series of CeO2 probe models were synthesized with different ratios of surface-to-bulk oxygen vacancies. Besides the devotion of the surface vacancies, a part of the bulk vacancies promotes the redox property of CeO2 in toluene catalytic combustion: surface vacancies tend to adsorb and activate gaseous O2 to form adsorbed oxygen species, whereas bulk vacancies improve the mobility and activity of lattice oxygen species via their transmission effect. Adsorbed oxygen mainly participates in the chemical adsorption and partial oxidation of toluene (mostly to phenolate). With the elevated temperatures, lattice oxygen of the catalysts facilitates the decomposition of aromatic rings and further improves the oxidation of toluene to CO2.

Roles of Oxygen Vacancies of CeO2 and Mn-Doped CeO2 with the Same Morphology in Benzene Catalytic Oxidation

“…Therefore, the Ce M 4,5 -edge EELS spectra were used to further investigate the distribution conditions of Ce 3+ and oxygen vacancies (Figure 5b). The proportions of Ce 3+ ([Ce 3+ ]) were calculated via the M 5 /M 4 white-line ratios for every sample [39]. The data show that the relative proportions of Ce 3+ in Ce-Mn-NF (0.876) and Ce-Mn-NC (0.837) are more than those of CeO 2 with the same morphology (CeO 2 -NF: 0.775, CeO 2 -NC: 0.765) due to Mn n+ replacing some Ce 4+ , which indicate that abundant Ce 3+ exists on the surface of Mn-doped CeO 2 and more oxygen vacancies are formed.…”

Catalytic Decomposition of Residual Ozone over Cactus-like MnO2 Nanosphere: Synergistic Mechanism and SO2/H2O Interference

“…As shown in Figure 5 b, the desorption peaks below 250 °C were associated with physically adsorbed oxygen. The peaks in the range of 250–600 °C were attributed to the release of the chemically adsorbed oxygen species, 52 as well as part of the subsurface lattice oxygen, 53 while the peaks above 600 °C were attributed to the bulk lattice oxygen species. 54 , 55 Both MnO 2 -IV and MnO 2 -I had obvious desorption peaks below 250 °C, which had a relatively good catalytic activity, coinciding with the reported studies that the deO 3 activity was related to the low-temperature oxygen adsorption–desorption properties.…”

Enhanced antibacterial activity of acid treated MgO nanoparticles on Escherichia coli

“…4d) than pure-MgO, which might be caused by the acid treatment. 32 To identify oxygen vacancies, the ESR measurement was adopted. The ESR signal was obtained from equal mass of MgO samples, thus the sample with stronger signal corresponds with more oxygen vacancies.…”