Jiang Yuheng, Zhao Wenshi, Li Siyang, Wang Shikun, Fan Yingying, Wang Fei, Qiu Xueying, Zhu Yanfei, Zhang Yin, Long Chang, Tang Zhiyong
Chinese Academy of Science (CAS) Key Laboratory of Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China.
Center for Nanoscale Science and Technology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, P. R. China.
J Am Chem Soc. 2022 Sep 7;144(35):15977-15987. doi: 10.1021/jacs.2c04884. Epub 2022 Aug 15.
Photocatalytic conversion of methane to value-added products under mild conditions, which represents a long sought-after goal for industrial sustainable production, remains extremely challenging to afford high production and selectivity using cheap catalysts. Herein, we present the crystal phase engineering of commercially available anatase TiO via simple thermal annealing to optimize the structure-property correlation. A biphase catalyst with anatase (90%) and rutile (10%) TiO with the optimal phase interface concentration exhibits exceptional performance in the oxidation of methane to formaldehyde under the reaction conditions of water solvent, oxygen atmosphere, and full-spectrum light irradiation. An unprecedented production of 24.27 mmol g with an excellent selectivity of 97.4% toward formaldehyde is acquired at room temperature after a 3 h reaction. Both experimental results and theoretical calculations disclose that the crystal phase engineering of TiO lengthens the lifetime of photogenerated carriers and favors the formation of intermediate methanol species, thus maximizing the efficiency and selectivity in the aerobic oxidation of methane to formaldehyde. More importantly, the feasibility of the scale-up production of formaldehyde is demonstrated by inventing a "pause-flow" reactor. This work opens the avenue toward industrial methane transformation in a sustainable and economical way.
在温和条件下将甲烷光催化转化为高附加值产品，这是工业可持续生产长期追求的目标，但使用廉价催化剂实现高产量和高选择性仍然极具挑战性。在此，我们通过简单的热退火对市售锐钛矿型TiO₂进行晶相工程，以优化结构-性能关系。一种具有90%锐钛矿相和10%金红石相TiO₂且具有最佳相界面浓度的双相催化剂，在水溶剂、氧气气氛和全光谱光照射的反应条件下，在将甲烷氧化为甲醛方面表现出卓越性能。经过3小时反应，在室温下获得了前所未有的24.27 mmol g⁻¹的产量，对甲醛的选择性高达97.4%。实验结果和理论计算均表明，TiO₂的晶相工程延长了光生载流子的寿命，并有利于中间甲醇物种的形成，从而使甲烷有氧氧化为甲醛的效率和选择性最大化。更重要的是，通过发明一种“间歇-流动”反应器，证明了甲醛规模化生产的可行性。这项工作为以可持续和经济的方式实现工业甲烷转化开辟了道路。
