Metal‐Oxo Electronic Tuning via In Situ CO Decoration for Promoting Methane Conversion to Oxygenates over Single‐Atom Catalysts

• Published in: Angewandte Chemie 2024-04, Vol.136 (16), p.n/a
• Main Authors: Xu, Weibin, Liu, Han‐Xuan, Hu, Yue, Wang, Zhen, Huang, Zheng‐Qing, Huang, Chuande, Lin, Jian, Chang, Chun‐Ran, Wang, Aiqin, Wang, Xiaodong, Zhang, Tao
• Format: Article
• Language: English
• Subjects: Catalysts; C−H bond activation; Decoration; direct methane conversion; Dissociation; Electron density; Electronic structure; Heavy metals; heterolytic dissociation of C−H bond; Hydrogen bonds; Hydrogen peroxide; Low temperature; Methane; molecular decoration; Oxidants; Oxidation; Oxidizing agents; Palladium; PD-1 protein; Room temperature; Single atom catalysts; Tuning
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202315343

Direct methane conversion (DMC) to oxygenates at low temperature is of great value but remains challenging due to the high energy barrier for C−H bond activation. Here, we report that in situ decoration of Pd1‐ZSM‐5 single atom catalyst (SAC) by CO molecules significantly promoted the DMC reaction, giving the highest turnover frequency of 207 h−1 ever reported at room temperature and ~100 % oxygenates selectivity with H2O2 as oxidant. Combined characterizations and DFT calculations illustrate that the C‐atom of CO prefers to coordinate with Pd1, which donates electrons to the Pd1−O active center (L−Pd1−O, L=CO) generated by H2O2 oxidation. The correspondingly improved electron density over Pd−O pair renders a favorable heterolytic dissociation of C−H bond with low energy barrier of 0.48 eV. Applying CO decoration strategy to M1‐ZSM‐5 (M=Pd, Rh, Ru, Fe) enables improvement of oxygenates productivity by 3.2–11.3 times, highlighting the generalizability of this method in tuning metal‐oxo electronic structure of SACs for efficient DMC process. In situ CO decoration can significantly tune the electronic state of metal‐oxo center in single‐atom catalysts for promoting oxygenates production. CO activated Pd1‐ZSM‐5 displays the highest turnover frequency of 207 h−1 and ~100 % oxygenates selectivity with H2O2 as oxidant at 25 °C.