Tandem Catalysis for Selective Oxidation of Methane to Oxygenates Using Oxygen over PdCu/Zeolite
Bo Wu, Tiejun Lin, Min Huang, Shenggang Li, Ji Li, Yu Xing, Ruoou Yang, Fanfei Sun, Zheng Jiang, Yuhan Sun, Liangshu Zhong
Abstract
Abstract Selective oxidation of methane to oxygenates with O 2 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 2 in the presence of H 2 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 −1 Pd h −1 (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 2 O 2 from O 2 and H 2 , while Cu single atoms not only accelerated the activation of H 2 O 2 for the generation of abundant hydroxyl radicals (⋅OH) from H 2 O 2 decomposition, but also enabled the homolytic cleavage of CH 4 by ⋅OH to methyl radicals (⋅CH 3 ). Subsequently, the ⋅OH reacted quickly with the ⋅CH 3 to form CH 3 OH with high selectivity.