Surface Self-Cleaning Effect of Bifunctional Catalyst To Boost the High Yield Production of Aromatics Directly from Syngas

• Published in: ACS catalysis 2024-05, Vol.14 (11), p.8972-8982
• Main Authors: Zhang, Lin, Su, Junjie, Liu, Chang, Liu, Su, Zhou, Haibo, Jiao, Wenqian, Hu, Yongfeng, Xiong, Feng, Lu, Yiqing, Ye, Yingchun, Zheng, Xusheng, Zhang, Yida, Wang, Yangdong, He, Heyong
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.4c01110

Direct synthesis of aromatics from syngas (STA) over an oxide–zeolite bifunctional catalyst is promising as a petroleum alternative route. Aromatics space-time yield (STY) is a key parameter for measuring the production capacity in an industrial process. However, it is still a great challenge to achieve high aromatics STY for industrial applications. Herein, we synthesized a series of CeMnO x catalysts with a self-cleaning effect. The structures and reduction process of CeMnO x catalysts were thoroughly characterized by X-ray absorption fine structure and in situ X-ray diffraction. Changes in surface carbon species during the reaction are revealed by in situ X-ray photoelectron spectroscopy and in situ Raman spectroscopy. Our results demonstrate that the intermediates can be converted to long-chain hydrocarbon or even graphite carbon species which can cover the surface of MnO x , inhibiting the reactants from further interacting with the active sites. Ce promotion in MnO x may remove the dissociated carbon species from the oxide surface by converting excess surface carbon species into short-chain hydrocarbons; thus, the growth of graphite carbon species is inhibited. This self-cleaning effect of CeMnO x catalysts facilitates the syngas conversion via maintaining a high exposure of active sites during the reaction, especially under high pressure and temperature. The aromatics STY (on carbon base) can reach as high as 4.27 mmol g–1 h–1 over CeMnO x +HZSM-5 bifunctional catalyst, which outperforms the data previously reported.