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<p>Zn-modified ZSM-5 catalysts are widely used in alkane aromatization. Self-pillared ZSM-5 zeolites are ideal supports to anchor metals due to their high specific surface areas and abundant Si-OH defects, facilitating the dispersion of metal precursors in the zeolite. In this work, with self-pillared ZSM-5 zeolite nanosheets as the support, Zn<sub><i>x</i></sub>/SPZSM-5 catalysts were prepared by the incipient wet impregnation method, and the evolution in structure, acidity, and Zn species distribution was studied. Their catalytic performance for <i>n</i>-octane aromatization was also evaluated. NH<sub>3</sub>-temperature-programmed desorption, pyridine adsorption infrared spectra, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy results indicated that [ZnOH]<sup>+</sup> species are formed by introducing zinc into ZSM-5 zeolite, at the expense of the silanol hydroxyl and proton acid sites. The distribution of acid sites, the nature of zinc species, and the subsequent catalytic performance of Zn<sub><i>x</i></sub>/SPZSM-5 catalysts in <i>n</i>-octane aromatization are significantly influenced by the zinc contents. A linear correlation exists between the amount of [ZnOH]<sup>+</sup> species and the selectivity of aromatics for <i>n</i>-octane aromatization over the Zn<sub><i>x</i></sub>/SPZSM-5 catalysts. This could be attributed to the [ZnOH]<sup>+</sup> species being a critical species for promoting BTX (benzene, toluene, and xylene) formation, which can enhance the alkanes dehydrogenation and olefins aromatization, thus improving BTX selectivity.</p>

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Aromatization of n-octane catalyzed by [ZnOH]+ species on self-pillared nanosheet ZSM-5 zeolite catalysts

  • 期刊论文

  • 发表日期：

    2025年8月1日

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  • Peng Wang,
  • Jianjie Wang,
  • Xiaolong Shu,
  • Mengqi Bian,
  • Xia Xiao,
  • Dong Li,
  • Xiaoqiang Fan,
  • Lian Kong,
  • Zean Xie,
  • Zhen Zhao

摘要

Zn-modified ZSM-5 catalysts are widely used in alkane aromatization. Self-pillared ZSM-5 zeolites are ideal supports to anchor metals due to their high specific surface areas and abundant Si-OH defects, facilitating the dispersion of metal precursors in the zeolite. In this work, with self-pillared ZSM-5 zeolite nanosheets as the support, Znx/SPZSM-5 catalysts were prepared by the incipient wet impregnation method, and the evolution in structure, acidity, and Zn species distribution was studied. Their catalytic performance for n-octane aromatization was also evaluated. NH3-temperature-programmed desorption, pyridine adsorption infrared spectra, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy results indicated that [ZnOH]+ species are formed by introducing zinc into ZSM-5 zeolite, at the expense of the silanol hydroxyl and proton acid sites. The distribution of acid sites, the nature of zinc species, and the subsequent catalytic performance of Znx/SPZSM-5 catalysts in n-octane aromatization are significantly influenced by the zinc contents. A linear correlation exists between the amount of [ZnOH]+ species and the selectivity of aromatics for n-octane aromatization over the Znx/SPZSM-5 catalysts. This could be attributed to the [ZnOH]+ species being a critical species for promoting BTX (benzene, toluene, and xylene) formation, which can enhance the alkanes dehydrogenation and olefins aromatization, thus improving BTX selectivity.