Discovering the key role of MnO2 and CeO2 particles in the Fe2O3 catalysts for enhancing the catalytic oxidation of VOC: Synergistic effect of the lattice oxygen species and surface-adsorbed oxygen

Wissem Ben Soltan; Jing Sun; Wenlong Wang; Zhanlong Song; Xiqiang Zhao; Yanpeng Mao; Zhichao Zhang

doi:10.1016/j.scitotenv.2021.152844

Discovering the key role of MnO₂ and CeO₂ particles in the Fe₂O₃ catalysts for enhancing the catalytic oxidation of VOC: Synergistic effect of the lattice oxygen species and surface-adsorbed oxygen

Sci Total Environ. 2022 May 1:819:152844. doi: 10.1016/j.scitotenv.2021.152844. Epub 2022 Jan 14.

Authors

Wissem Ben Soltan¹, Jing Sun², Wenlong Wang³, Zhanlong Song¹, Xiqiang Zhao¹, Yanpeng Mao¹, Zhichao Zhang⁴

Affiliations

¹ National Engineering Laboratory for Reducing Emissions from Coal Combustion, Engineering Research Center of Environmental Thermal Technology of Ministry of Education, Shandong Key Laboratory of Energy Carbon Reduction and Resource Utilization, School of Energy and Power Engineering, Shandong University, Jinan, Shandong 250061, China.
² National Engineering Laboratory for Reducing Emissions from Coal Combustion, Engineering Research Center of Environmental Thermal Technology of Ministry of Education, Shandong Key Laboratory of Energy Carbon Reduction and Resource Utilization, School of Energy and Power Engineering, Shandong University, Jinan, Shandong 250061, China. Electronic address: sunjing0108@163.com.
³ National Engineering Laboratory for Reducing Emissions from Coal Combustion, Engineering Research Center of Environmental Thermal Technology of Ministry of Education, Shandong Key Laboratory of Energy Carbon Reduction and Resource Utilization, School of Energy and Power Engineering, Shandong University, Jinan, Shandong 250061, China. Electronic address: wwenlong@sdu.edu.cn.
⁴ Shandong Huanwo Environmental Protection Technology Co., ltd., Binzhou, Shandong 251800, China.

PMID: 35038514
DOI: 10.1016/j.scitotenv.2021.152844

Abstract

Highly active mesoporous Fe-Mn-Ce catalysts with high specific surface area (S_BET) were synthesized by a modified precipitation process for catalyzing toluene oxidation. The Fe_0.85Mn_0.1Ce_0.05 catalyst presents richer surface oxygen species (OS), a higher proportion of Mn⁴⁺ and Ce⁴⁺, a higher concentration of lattice defects and oxygen vacancies, the highest O_ads/O_latt ratio, and a superior low-temperature redox property compared with the Fe-Mn binary oxide and Fe₂O₃ and MnO₂ catalysts. The properties contribute to a high catalytic activity to achieve T₉₀% of toluene conversion at 264 °C and 185 °C with a gas hourly space velocity (GHSV) at 180,000 and 20,000 mL/(g∙h), respectively. The introduction of a slight quantity of Ce and Mn onto the Fe₂O₃ catalyst is the key to enhancing the synergistic effect of the lattice OS and surface-adsorbed oxygen, contributing to the activation oxidation procedure of toluene. In-situ DRIFTS analysis reveals that the rich oxygen vacancy concentration of catalysts accelerates the key steps for the generation and activation of oxidized products. These catalysts with rich oxygen vacancies can efficiently diminish the accumulation of a small number of the intermediary species (phenolate, C₆H₅-OH) produced during the catalytic oxidation of toluene.

Keywords: Catalytic oxidation of toluene; Mesoporous Fe-Mn-Ce catalysts; Oxygen vacancies; Precipitation process.