Highly Enhanced Aromatics Selectivity by Coupling of Chloromethane and Carbon Monoxide over H-ZSM-5
Xudong Fang1,2, Hongchao Liu1, Zhiyang Chen1,2
1National Engineering Laboratory for Methanol to Olefins, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
Abstract:
The transformation of methane into high value-added chemicals such as aromatics provides a more desired approach towards sustainable chemistry but remains a critical challenge due to the low selectivity of aromatics and poor stability. Herein, we first report a coupling reaction of CH3 Cl and CO (CCTA) based on methane conversion, which achieves extremely high aromatics selectivity (82.2 %) with the selectivity of BTX up to ca. 60 % over HZSM-5. The promoting effects have been demonstrated on other zeolites especially 10-membered rings (10 MR) zeolites. Multiple characterizations show that 2,3-dimethyl-2-cyclopentene-1-one (DMCPO) is generated from acetyl groups and olefins. Furthermore, isotopic labeling analysis confirms that CO is 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, leading to a considerable increase of aromatics selectivity and a dramatic drop in alkanes.
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