Methane, the main constituent in shale gas and flammable ice, is expected to replace petroleum to produce high value-added chemicals such as aromatics. However, methane’s relatively highly inert which is resulting from the high C-H bond strength and supersymmetric structure hinders its applications.
Recently, the research team led by Prof. LIUZhongmin and Prof. ZHU Wenliang developed an efficient reaction strategy for the transformation of methane into aromatics by coupling of CH3Cl with CO over H-zeolites.
This study was published in Angew. Chem. Int. Ed. on 1 Feb. It was selected as Very Important Paper and inside back cover.
Highly Enhanced Aromatics Selectivity by Coupling of Chloromethane and Carbon Monoxide over H-ZSM-5 (Image by FANG Xudong)
The researchers used HZSM-5 as catalysts to achieve high aromatics selectivity as well as high selectivity of BTX (benzene, toluene, and xylene).They found that the selectivity to aromatics increases from 39.0% to 79.3% after introducing CO, and corresponding BTX selectivity also increases from 17.7% to 48.0%at 2.0 MPa, 673 K. After optimizing reaction conditions, aromatics selectivity as high as 82.2% (BTX selectivity up to 59.3%) was obtained, which is far higher than any prior results reported in the literature.
Moreover, multiple characterizations, such as in situ DRIFT and 13C isotope labeling experiments show that 2,3-dimethyl-2-cyclopentene-1-one (DMCPO) is generated from acetyl groups and olefins. Furthermore, CO is proven to be inserted into the DMCPO and aromatics rings. A new aromatization mechanism is proposed, including the formation of the above intermediates, which conspicuously weakens the hydrogen transfer reaction, resulting in a considerable increase in aromatics selectivity and a dramatic drop in alkanes.
“Our study broadens approaches towards the transformation of methane into chemicals, and ensure the sustainable development of natural gas in an environmental pathway,” said Prof. ZHU.
The study was supported by the National Natural Science Foundation of China,the Strategic Priority Research Program of CAS, the Dalian High-Level Talent Innovation Support Program, and National Special Support Program for High-Level Talents. (Text by FANG Xudong and LIU Hongchao)
Highly Enhanced Aromatics Selectivity by Coupling of Chloromethane and Carbon Monoxide over H-ZSM-5.Xudong Fang,Hongchao Liu,*Zhiyang Chen,Zhaopeng Liu,Xiangnong Ding,Youming Ni,Wenliang Zhu,*and Zhongmin Liu*, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION,61:e202114953, 2022.
