High n-Hexane Adsorption Capacity of Composite Adsorbents Based on MOFs and Graphene with Various Morphologies

High ratio of Ce3+/(Ce3++Ce4+) enhanced the plasma catalytic degradation of n-undecane on CeO2/γ-Al2O3

n-Undecane (C11) is the main component of volatile organic compounds (VOCs) emitted from the printing industry, and its emission to the atmosphere should be controlled. In this study, a dielectric barrier discharge reactor coupled with CeO₂/γ-Al₂O₃ catalysts was used to degrade C11. The effect of the chemical state of CeO₂ on C11 degradation was evaluated by varying the CeO₂ loading on γ-Al₂O₃. The C11 conversion and COx selectivity were as high as 92% and 80%, respectively, under mild reaction conditions of energy density 34 J/L and 423 K to degrade 134 mg/m³ C11 in a simulated air using 10 wt%CeO₂ impregnated on γ-Al₂O₃. After analyses using in-situ plasma diffuse reflectance Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry, it was found that most of C11 were degraded to CO₂, and the main by-products on catalyst surfaces were alcohols and ketones. It was concluded from X-ray photoemission spectroscopy that the good performance of the 10 wt%CeO₂/γ-Al₂O₃ catalyst was due to its high Ce³⁺/(Ce³⁺+Ce⁴⁺) ratio as well as the oxygen vacancies. The Ce³⁺/(Ce³⁺+Ce⁴⁺) ratio of CeO₂ on γ-Al₂O₃ is crucial for the degradation of C11, providing a further roadmap for the plasma catalytic oxidation of alkanes.