Catalytic oxidation of toluene by manganese oxides: Effect of K+ doping on oxygen vacancy.
J Environ Sci (China)
; 142: 43-56, 2024 Aug.
Article
em En
| MEDLINE
| ID: mdl-38527895
ABSTRACT
Alkali metal potassium was beneficial to the electronic regulation and structural stability of transition metal oxides. Herein, K ions were introduced into manganese oxides by different methods to improve the degradation efficiency of toluene. The results of activity experiments indicated that KMnO4-HT (HT Hydrothermal method) exhibited outstanding low-temperature catalytic activity, and 90% conversion of toluene can be achieved at 243°C, which was 41°C and 43°C lower than that of KNO3-HT and Mn-HT, respectively. The largest specific surface area was observed on KMnO4-HT, facilitating the adsorption of toluene. The formation of cryptomelane structure over KMnO4-HT could contribute to higher content of Mn3+ and lattice oxygen (Olatt), excellent low-temperature reducibility, and high oxygen mobility, which could increase the catalytic performance. Furthermore, two distinct degradation pathways were inferred. Pathway â
(KMnO4-HT) toluene â benzyl â benzoic acid â carbonate â CO2 and H2O; Pathway â
â
(Mn-HT) toluene â benzyl alcohol â benzoic acid â phenol â maleic anhydride â CO2 and H2O. Fewer intermediates were detected on KMnO4-HT, indicating its stronger oxidation capacity of toluene, which was originated from the doping of K+ and the interaction between KOMn. More intermediates were observed on Mn-HT, which can be attributed to the weaker oxidation ability of pure Mn. The results indicated that the doping of K+ can improve the catalytic oxidation capacity of toluene, resulting in promoted degradation of intermediates during the oxidation of toluene.
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MEDLINE
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En
Ano de publicação:
2024
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Article