Wu Bo, Lin Tiejun, Huang Min, Li Shenggang, Li Ji, Yu Xing, Yang Ruoou, Sun Fanfei, Jiang Zheng, Sun Yuhan, Zhong Liangshu
CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201210, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Angew Chem Int Ed Engl. 2022 Jun 13;61(24):e202204116. doi: 10.1002/anie.202204116. Epub 2022 Apr 20.
Selective oxidation of methane to oxygenates with O under mild conditions remains a great challenge. Here we report a ZSM-5 (Z-5) supported PdCu bimetallic catalyst (PdCu/Z-5) for methane conversion to oxygenates by reacting with O in the presence of H at low temperature (120 °C). Benefiting from the co-existence of PdO nanoparticles and Cu single atoms via tandem catalysis, the PdCu/Z-5 catalyst exhibited a high oxygenates yield of 1178 mmol g h (mmol of oxygenates per gram Pd per hour) and at the same time high oxygenates selectivity of up to 95 %. Control experiments and mechanistic studies revealed that PdO nanoparticles promoted the in situ generation of H O from O and H , while Cu single atoms not only accelerated the activation of H O for the generation of abundant hydroxyl radicals (⋅OH) from H O decomposition, but also enabled the homolytic cleavage of CH by ⋅OH to methyl radicals (⋅CH ). Subsequently, the ⋅OH reacted quickly with the ⋅CH to form CH OH with high selectivity.
在温和条件下用氧气将甲烷选择性氧化为含氧化合物仍然是一个巨大的挑战。在此，我们报道了一种ZSM-5（Z-5）负载的PdCu双金属催化剂（PdCu/Z-5），用于在低温（120 °C）、氢气存在的情况下，使甲烷与氧气反应转化为含氧化合物。得益于通过串联催化共存的PdO纳米颗粒和Cu单原子，PdCu/Z-5催化剂表现出1178 mmol g h（每克钯每小时含氧化合物的毫摩尔数）的高含氧化合物产率，同时含氧化合物选择性高达95%。对照实验和机理研究表明，PdO纳米颗粒促进了氧气和氢气原位生成过氧化氢，而Cu单原子不仅加速了过氧化氢的活化，使其从过氧化氢分解中产生大量羟基自由基（⋅OH），还能使⋅OH将CH均裂为甲基自由基（⋅CH ）。随后，⋅OH与⋅CH 快速反应，以高选择性形成CH OH。
