1. CO2-Assisted in situ hydrogen extraction for highly selective aromatization of n-Hexane over Zn modified HZSM-5 catalyst.
- Author
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Chen, Xiaobo, Ren, Delun, Yan, Hao, Li, Zhiqiang, Zhang, Xinyang, Luan, Bo, Wang, Yaowei, Shi, Huibing, Jiang, Haiying, Hu, Yuhang, Hu, Xue, Zhang, Aijie, Dong, Mingyuan, Zhou, Xin, Feng, Xiang, Liu, Yibin, and Yang, Chaohe
- Subjects
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IN situ processing (Mining) , *HYDROGEN transfer reactions , *AROMATIZATION , *INTERSTITIAL hydrogen generation , *CARBON dioxide , *CATALYSTS , *SOLVENT extraction - Abstract
We successfully realized the highly selective aromatization of n-hexane by the assistance of CO 2 over Zn modified HZSM-5 catalyst. The in situ H originated from the C-H activation of n-hexane and cyclohexane could be timely removed through the dynamic evolution between CO 2 and Lewis acid site, thus inhibiting the hydrogen transfer side reaction and promoting the desorption of BTEX. Therefore, the Zn/ZSM-5-CO 2 catalyst exhibits as high as 49.7% BTEX yield, which is nearly 10% higher than that of the Zn/ZSM-5-N 2 catalyst (40.3%). [Display omitted] • The introduction of CO 2 could timely remove the in situ H. • Hydrogen transfer between olefins and aromatics is effectively inhibited. • The binding of hydrogen proton to π electrons is weakened. • The loss of medium strength Lewis acid is significantly reduced. • The Zn/ZSM-5-CO 2 catalyst exhibits as high as 49.7% BTEX yield and superior catalytic stability. Controlling the evolution of H species in CO 2 -assisted alkane activation represents an opportunity for simultaneously upgrading light alkanes and greenhouse gas CO 2. Herein, we successfully realized the highly selective aromatization of n -hexane by the assistance of CO 2 over Zn modified HZSM-5 catalyst. Multi-characterizations demonstrated that the introduction of CO 2 could timely remove the in situ H originated from the C-H activation of n -hexane and cyclohexane through the dynamic evolution of the pentagonal coordination Zn-OH+-(CO)-O-Zn structure. On this basis, hydrogen transfer between olefins and aromatics is effectively inhibited, and the binding between π electrons of benzene ring and hydrogen proton is weakened, accelerating the generation and desorption of BTEX. Therefore, the Zn/ZSM-5-CO 2 displays a record high 49.7% BTEX yield, which is nearly 10% higher than that of the Zn/ZSM-5-N 2 (40.3%). In addition, the loss of medium strength Lewis acid caused by in situ H reduction of Si(Al)-O-Zn structure is significantly reduced, ensuring its superior catalytic stability under long-term conditions. These results may provide some insights for the profitable utilization of petrochemical resources to aromatics over zeolites. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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