State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China.
Environ Sci Technol. 2020 Nov 17;54(22):14465-14473. doi: 10.1021/acs.est.0c06048. Epub 2020 Oct 29.
This work presents a new strategy for industrial flue gas purification with TiO-based photocatalysis technology, which could be achieved by a novel dual-stage circulating photocatalytic reactor. A lab-scale fixed bed reactor is utilized to investigate the performance of photocatalytic toluene degradation and inactive catalyst regeneration by thermal/UV treatment. The relationships between operational conditions and toluene oxidation are surveyed and discussed in detail. The results show that the intermediates could be further removed and decomposed by introducing UV radiation, compared with heat treatment alone. To reveal the photocatalytic mechanism and identify the accumulated intermediates over anatase TiO, the adsorbed toluene and aromatic intermediates are identified by XPS, DRIFTS, and on-line MS. The aromatic ring and other covalent bonds (C═O, C-O, and O-H) are detected during photocatalytic oxidation. The reaction pathway involving hydrogen abstraction is referred as the dominant pathway for toluene degradation, and ring opening via ·OH radicals is crucial to make aromatic intermediates change into CO and HO. The results indicate that benzoic acid and benzaldehyde are the main accumulation because of their high reaction energy. A possible reaction mechanism is proposed for toluene oxidation, deactivation, and regeneration of catalysts, which has a significant value for guiding the practical applications.
本工作提出了一种利用 TiO2 光催化技术净化工业烟道气的新策略，该策略可通过新型双级循环光催化反应器实现。利用实验室规模的固定床反应器研究了光催化甲苯降解和热/UV 处理再生失活催化剂的性能。详细考察和讨论了操作条件与甲苯氧化之间的关系。结果表明，与单独热处理相比，引入 UV 辐射可进一步去除和分解中间产物。为了揭示光催化机制并确定锐钛矿 TiO2 上积累的中间产物，通过 XPS、DRIFTS 和在线 MS 对吸附的甲苯和芳烃中间体进行了鉴定。在光催化氧化过程中检测到芳环和其他共价键（C═O、C-O 和 O-H）。氢提取反应途径被认为是甲苯降解的主要途径，而·OH 自由基开环对于使芳烃中间体转化为 CO 和 HO 至关重要。结果表明，由于其高反应能，苯甲酸和苯甲醛是主要的积累物。提出了一种可能的甲苯氧化、催化剂失活和再生反应机制，对指导实际应用具有重要价值。
