Efficient Catalytic Combustion of Cyclohexane over PdAg/Fe 2 O 3 Catalysts under Low-Temperature Conditions: Establishing the Degradation Mechanism Using PTR-TOF-MS and in Situ DRIFTS.

Cyclohexane, a typical volatile organic compound (VOC), poses high risks to the environment and humans. Herein, synthesized PdAg/Fe ₂ O ₃ catalysts exhibited exceptional catalytic performance for cyclohexane combustion at lower temperatures (50% mineralization temperature ( T ₅₀ ) of 199 °C, 90% mineralization temperature ( T ₉₀ ) of 315 °C) than Pd/Fe ₂ O ₃ ( T ₅₀ of 262 °C, T ₉₀ of 335 °C) and Fe ₂ O ₃ ( T ₅₀ of 305 °C, T ₉₀ of 360 °C). In addition, PdAg/Fe ₂ O ₃ displayed enhanced stability by alloying Ag with Pd. The redox and acidity of the PdAg/Fe ₂ O ₃ were studied by XPS, H ₂ -TPR, and NH ₃ -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 Fe ₂ O ₃ 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.