Reheat treatment under vacuum induces pre-calcined α-MnO2 with oxygen vacancy as efficient catalysts for toluene oxidation

Ruimei Fang; Jing Huang; Xinyue Huang; Xiao'ai Luo; Yanjuan Sun; Fan Dong; Haibao Huang

doi:10.1016/j.chemosphere.2021.133081

Reheat treatment under vacuum induces pre-calcined α-MnO₂ with oxygen vacancy as efficient catalysts for toluene oxidation

Chemosphere. 2022 Feb:289:133081. doi: 10.1016/j.chemosphere.2021.133081. Epub 2021 Nov 26.

Authors

Ruimei Fang¹, Jing Huang², Xinyue Huang³, Xiao'ai Luo⁴, Yanjuan Sun⁵, Fan Dong⁴, Haibao Huang⁶

Affiliations

¹ College of Environment and Resources, Chongqing Technology and Business University, Chongqing, 400067, China. Electronic address: fangruimei@126.com.
² College of Environment and Resources, Chongqing Technology and Business University, Chongqing, 400067, China.
³ College of Environment and Resources, Chongqing Technology and Business University, Chongqing, 400067, China; Yangtze Delta Region Institute (Huzhou) & School of Resources and Environment, University of Electronic Science and Technology of China, Huzhou, 313000, China.
⁴ College of Environment and Resources, Chongqing Technology and Business University, Chongqing, 400067, China; Yangtze Delta Region Institute (Huzhou) & Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Huzhou, 313000, China.
⁵ College of Environment and Resources, Chongqing Technology and Business University, Chongqing, 400067, China; Yangtze Delta Region Institute (Huzhou) & School of Resources and Environment, University of Electronic Science and Technology of China, Huzhou, 313000, China. Electronic address: syhsyj@163.com.
⁶ School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China.

PMID: 34843838
DOI: 10.1016/j.chemosphere.2021.133081

Abstract

Engineering α-MnO₂ with abundant oxygen vacancies is efficient to enhance its catalytic activity towards toluene oxidation. A simple and facile method was introduced to fabricate oxygen vacancies on α-MnO₂ surface by reheating the pre-calcined samples under vacuum condition. The reheat treatment especially at 180 °C is beneficial for the formation of oxygen vacancies on α-MnO₂ surface, enhancing the oxidation of toluene. The toluene conversion is up to 100% at 270 °C, which is 30 °C lower than that of α-MnO₂ without reheat treatment. The apparent activation energy (16.8 kJ mol^-1) of MnO₂-180 catalyst is lowest among these catalysts, which is essential for accelerating the oxidation of toluene. In-situ DRIFTS results indicate that the MnO₂-180 sample promotes the formation of benzaldehyde and the occurrence of ring-opening reaction, thus effectively improving the catalytic performance for toluene oxidation. A possible catalytic oxidation mechanism of toluene over α-MnO₂ catalysts after reheat treatment was proposed.

Keywords: Catalytic oxidation; Oxygen vacancies; Reheat treatment; Toluene; α-MnO(2).

MeSH terms

Catalysis
Manganese Compounds*
Oxides*
Oxygen
Toluene / analysis
Vacuum

Substances

Manganese Compounds
Oxides
Toluene
Oxygen