Efficient Catalytic Combustion of Cyclohexane over PdAg/Fe2O3 Catalysts under Low-Temperature Conditions: Establishing the Degradation Mechanism Using PTR-TOF-MS and in Situ DRIFTS

Qiuxia Liu; Meicheng Wen; Yunlong Guo; Shengnan Song; Guiying Li; Taicheng An

doi:10.1021/acsami.2c14515

Efficient Catalytic Combustion of Cyclohexane over PdAg/Fe₂O₃ Catalysts under Low-Temperature Conditions: Establishing the Degradation Mechanism Using PTR-TOF-MS and in Situ DRIFTS

ACS Appl Mater Interfaces. 2022 Dec 21;14(50):55503-55516. doi: 10.1021/acsami.2c14515. Epub 2022 Dec 1.

Authors

Qiuxia Liu^{1

2}, Meicheng Wen^{1

2}, Yunlong Guo^{1

2}, Shengnan Song^{1

2}, Guiying Li^{1

2}, Taicheng An^{1

2}

Affiliations

¹ Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou510006, China.
² Guangdong Engineering Technology Research Center for Photocatalytic Technology Integration and Equipment, Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou510006, China.

PMID: 36456474
DOI: 10.1021/acsami.2c14515

Abstract

Cyclohexane, a typical volatile organic compound (VOC), poses high risks to the environment and humans. Herein, synthesized PdAg/Fe₂O₃ catalysts exhibited exceptional catalytic performance for cyclohexane combustion at lower temperatures (50% mineralization temperature (T₅₀) of 199 °C, 90% mineralization temperature (T₉₀) of 315 °C) than Pd/Fe₂O₃ (T₅₀ of 262 °C, T₉₀ of 335 °C) and Fe₂O₃ (T₅₀ of 305 °C, T₉₀ of 360 °C). In addition, PdAg/Fe₂O₃ displayed enhanced stability by alloying Ag with Pd. The redox and acidity of the PdAg/Fe₂O₃ were studied by XPS, H₂-TPR, and NH₃-TPD. In situ diffuse reflectance infrared Fourier transform spectroscopy and proton-transfer-reaction time-of-flight mass spectrometry were applied to identify the intermediates formed on the catalyst surface and in the tail gas during oxidation, respectively. Results suggested that loading PdAg onto Fe₂O₃ significantly enhanced the adsorption and activation of oxygen and cyclohexane, oxidative dehydrogenation of cyclohexane to benzene, and catalytic cracking of cyclohexane to olefins at low temperatures. This in-depth study will benefit the design and application of efficient catalysts for the effective combustion of VOCs at low temperatures.

Keywords: PdAg/Fe2O3 catalysts; catalytic combustion; cyclohexane; degradation intermediates and mechanism; degradation kinetics.