Xie Jijia, Fu Cong, Quesne Matthew G, Guo Jian, Wang Chao, Xiong Lunqiao, Windle Christopher D, Gadipelli Srinivas, Guo Zheng Xiao, Huang Weixin, Catlow C Richard A, Tang Junwang
Department of Chemical Engineering, University College London, London, UK.
State Key Laboratory of Precision and Intelligent Chemistry, iChEM, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Department of Chemical Physics, University of Science and Technology of China, Hefei, China.
Nature. 2025 Mar;639(8054):368-374. doi: 10.1038/s41586-025-08630-x. Epub 2025 Jan 20.
Methane, the main component of natural and shale gas, is a significant carbon source for chemical synthesis. The direct partial oxidation of methane to liquid oxygenates under mild conditions is an attractive pathway, but the inertness of the molecule makes it challenging to achieve simultaneously high conversion and high selectivity towards a single target product. This difficulty is amplified when aiming for more valuable products that require C-C coupling. Whereas selective partial methane oxidation processes have thus typically generated C oxygenates, recent reports have documented photocatalytic methane conversion to the C oxygenate ethanol with low conversions but good-to-high selectivities. Here we show that the intramolecular junction photocatalyst covalent triazine-based framework-1 with alternating benzene and triazine motifs drives methane coupling and oxidation to ethanol with a high selectivity and significantly improved conversion. The heterojunction architecture not only enables efficient and long-lived separation of charges after their generation, but also preferential adsorption of HO and O to the triazine and benzene units, respectively. This dual-site feature separates C-C coupling to form ethane intermediates from the sites where •OH radicals are formed, thereby avoiding over-oxidation. When loaded with Pt to further boost performance, the molecular heterojunction photocatalyst generates ethanol in a packed-bed flow reactor with greatly improved conversion that results in an apparent quantum efficiency of 9.4%. We anticipate that further developing the 'intramolecular junction' approach will deliver efficient and selective catalysts for C-C coupling, pertaining, but not limited, to methane conversion to C chemicals.
甲烷是天然气和页岩气的主要成分，是化学合成的重要碳源。在温和条件下将甲烷直接部分氧化为液态含氧化合物是一条有吸引力的途径，但该分子的惰性使得同时实现高转化率和对单一目标产物的高选择性具有挑战性。当目标是获得需要碳 - 碳偶联的更有价值的产物时，这一困难会加剧。虽然选择性部分甲烷氧化过程通常会生成含碳氧合物，但最近的报道记录了光催化甲烷转化为含碳氧合物乙醇，转化率较低但选择性良好至高。在这里，我们表明具有交替苯环和三嗪基序的分子内结光催化剂共价三嗪基框架 -1 能以高选择性和显著提高的转化率驱动甲烷偶联和氧化生成乙醇。这种异质结结构不仅能使电荷产生后实现高效且长寿命的分离，还能使羟基和氧分别优先吸附到三嗪和苯单元上。这种双位点特性将碳 - 碳偶联形成乙烷中间体与形成羟基自由基的位点分开，从而避免过度氧化。当负载铂以进一步提高性能时，这种分子异质结光催化剂在填充床流动反应器中生成乙醇，转化率大幅提高，表观量子效率达到 9.4%。我们预计，进一步开发“分子内结”方法将为碳 - 碳偶联提供高效且选择性的催化剂，这适用于但不限于甲烷转化为含碳化学品。
