Synergistic Photocatalytic Treatment of Aromatic Hydrocarbons/NOx Mixtures Over TiO2: The Activation and Replenishment of Lattice Oxygen
Synergistic Photocatalytic Treatment of Aromatic Hydrocarbons/NOx Mixtures Over TiO2: The Activation and Replenishment of Lattice Oxygen
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DOI：
10.1016/j.cej.2022.138168
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发表时间：
2022-07
影响因子：
15.1
通讯作者：
Xiao Wang;A. Mahmood;Guanhong Lu;Xiaofeng Xie;Jing Sun
中科院分区：
文献类型：
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作者：
Xiao Wang;A. Mahmood;Guanhong Lu;Xiaofeng Xie;Jing Sun
通过原位FTIR和质谱分析吸附态和气相中间产物的演变，提出了单一芳烃/NOx气体的光催化氧化（PCO）机理及其在TiO 2（TiO 2）上的协同光催化处理。发现TiO 2表面晶格氧（TiO 2（·OL））对邻二甲苯和NOx的PCO都有很强的氧化作用，它们的消耗导致了光催化剂的失活。作为一种重要的共存污染物，NO被首次发现可以促进邻二甲苯、甲苯、苯乙烯和苯等芳烃的持续开环和降解。NO的PCO中间体NO2作为强氧化剂补充了TiO 2的晶格氧，保证了活性TiO 2（·OL）的持续生成，防止了光催化剂的失活。随着NO的引入，邻二甲苯的PCO效率从65%左右提高到100%，且在6 h内没有发生TiO 2性能衰减。芳烃的存在防止有毒的NO2逃逸到空气中，并促进NO无害地转化为亚硝酸根/硝酸根离子和N2。本文通过对芳烃/NOx混合物的协同稳定光催化处理过程的分析，阐述了晶格氧的活化和补充在PCO过程中的重要作用，探讨了PCO在空气净化中的应用潜力。
The photocatalytic oxidation (PCO) mechanisms of single aromatic hydrocarbons/NOxgases and the synergistic photocatalytic treatment of their mixtures over TiO2(anatase) are proposed by analyzing the evolution of adsorbed and gas-phase intermediates through in-situ FTIR and mass-spectroscopy. Photo-activated surface lattice oxygen of TiO2(TiO2(·OL)) is found to be a strong oxidant for the PCO of both o-xylene and NOxand their consumption led to the deactivation of photocatalysts. As an important coexist air pollutant, NO is firstly discovered as a helper for the persistent ring-opening and degradation of aromatics including o-xylene, toluene, styrene and benzene. NO2, a PCO intermediate of NO, acts as a powerful oxidant for replenishing lattice oxygen of TiO2, which guarantees the continuous generation of active TiO2(·OL) and prevents the deactivation of photocatalyst. With the introduction of NO, the PCO efficiency of o-xylene increases from ∼65% to 100% and no performance decay of TiO2happens in 6 h. The existence of aromatics prevents the escape of toxic NO2into air and promotes the harmless transformation of NO into nitrite/nitrate ions and N2. This work outlines the essential role of activation and replenishment of lattice oxygen in the PCO process by analyzing the synergistic and stable photocatalytic treatment of aromatic hydrocarbon/NOxmixtures, which explores the practical potentiality of photocatalysis in air purification.