Abstract
The direct functionalization of methane into platform chemicals is arguably one of the holy grails in chemistry. The actual active sites for methane activation are intensively debated. By correlating a wide variety of characterization results with catalytic performance data we have been able to identify mononuclear Fe species as the active site in the Fe/ZSM-5 zeolites for the mild oxidation of methane with H2O2at 50 °C. The 0.1% Fe/ZSM-5 catalyst with dominant mononuclear Fe species possess an excellent turnover rate (TOR) of 66 molMeOHmolFe−1h−1, approximately 4 times higher compared to the state-of-the-art dimer-containing Fe/ZSM-5 catalysts. Based on a series of advancedin situspectroscopic studies and1H- and13C- nuclear magnetic resonance (NMR), we found that methane activation initially proceeds on the Fe site of mononuclear Fe species. With the aid of adjacent Brønsted acid sites (BAS), methane can be first oxidized to CH3OOH and CH3OH, and then subsequently converted into HOCH2OOH and consecutively into HCOOH. These findings will facilitate the search towards new metal-zeolite combinations for the activation of C-H bonds in various hydrocarbons, for light alkanes and beyond.
| Original language | English |
|---|---|
| Pages (from-to) | 3152-3160 |
| Number of pages | 9 |
| Journal | Chemical Science |
| Volume | 12 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - 7 Mar 2021 |
Bibliographical note
Funding Information:Financial support for this work comes from the National Key Projects for Fundamental Research and Development of China (2016YFA0202801), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17020100), and the Foundation of Dalian Institute of Chemical Physics (DICP I201915), which are all gratefully acknowledged. B. Y. and Q. H. acknowledge the support of the National Natural Science Foundation of China (21872145) and National Research Foundation (NRF) of Singapore (NRFF11-2019-0051) respectively. W. J., D. M. F and A. M. B. acknowledge EPSRC and Yara international for funding. The X-ray absorption spectroscopy experiments were conducted at the Diamond and Shanghai Synchrotron Radiation Facility. We thank Xiaoge Bai from Tianjin Xianquan Instrument Co. for the assistance with FT-IR experiments and Yang Su for the assistance with STEM experiments. We also thank Dr Xuning Li and Prof. Fengtao Fan for the valuable discussion on57Fe M?ssbauer and IR results, respectively. We are also thankful to Prof. Tao Zhang for valuable discussion and suggestions.
Publisher Copyright:
© The Royal Society of Chemistry 2021.
Funding
Financial support for this work comes from the National Key Projects for Fundamental Research and Development of China (2016YFA0202801), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17020100), and the Foundation of Dalian Institute of Chemical Physics (DICP I201915), which are all gratefully acknowledged. B. Y. and Q. H. acknowledge the support of the National Natural Science Foundation of China (21872145) and National Research Foundation (NRF) of Singapore (NRFF11-2019-0051) respectively. W. J., D. M. F and A. M. B. acknowledge EPSRC and Yara international for funding. The X-ray absorption spectroscopy experiments were conducted at the Diamond and Shanghai Synchrotron Radiation Facility. We thank Xiaoge Bai from Tianjin Xianquan Instrument Co. for the assistance with FT-IR experiments and Yang Su for the assistance with STEM experiments. We also thank Dr Xuning Li and Prof. Fengtao Fan for the valuable discussion on57Fe M?ssbauer and IR results, respectively. We are also thankful to Prof. Tao Zhang for valuable discussion and suggestions.