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<p>ZSM-23 and γ-Al₂O₃ were first synthesized individually and subsequently combined to prepare a composite support by physical mixing in a 10:90 weight% ratio. A CoMo/composite catalyst was then produced via incipient wetness impregnation. The catalytic performance was evaluated in the hydrotreating of a model FCC naphtha feed containing thiophene (1000 ppm S), 1-hexene (20 vol%), and n-heptane (80 vol%). Hydrotreating experiments were conducted at T = 220–280&#xa0;°C, <i>P</i> = 2&#xa0;MPa, H₂/feed ratio of 120 NL/L, and LHSV values of 5 and 10&#xa0;h<sup>− 1</sup>. The supports and catalysts were characterized by X-ray diffraction, nitrogen adsorption–desorption, scanning electron microscopy, Fourier transform infrared spectroscopy, atomic absorption spectroscopy, NH₃-temperature-programmed desorption, and thermal gravimetric analysis. The incorporation of unidirectional pore structure ZSM-23 zeolite into γ-Al₂O₃ significantly modified the catalyst’s acidity, resulting in enhanced olefin isomerization and improved octane number retention. Under optimal isomerization conditions (240&#xa0;°C, LHSV of 10&#xa0;h⁻¹), the composite CoMo/AZ23 catalyst achieved an isomerization percentage of 66.8%, compared to 53.3% for the conventional CoMo/γ-Al₂O₃. Consequently, under these conditions, the composite catalyst preserved fuel quality with a slight octane number increase (+ 0.1), effectively preventing the significant 2.5-unit loss associated with the conventional catalyst. This breakthrough directly enables the development of industrial hydrotreating catalysts capable of producing higher-value fuels.</p> Graphical abstract <p></p>

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Enhanced olefin isomerization over CoMo/ZSM-23-γ-Al₂O₃ composite catalyst in hydrotreating of FCC naphtha

  • 期刊论文

  • 发表日期：

    2026年1月5日

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  • Zahra Mirghiasi,
  • Seyed Mahdi Latifi,
  • Mehdi Rashidzadeh,
  • Hamid Kiarad

摘要

ZSM-23 and γ-Al₂O₃ were first synthesized individually and subsequently combined to prepare a composite support by physical mixing in a 10:90 weight% ratio. A CoMo/composite catalyst was then produced via incipient wetness impregnation. The catalytic performance was evaluated in the hydrotreating of a model FCC naphtha feed containing thiophene (1000 ppm S), 1-hexene (20 vol%), and n-heptane (80 vol%). Hydrotreating experiments were conducted at T = 220–280 °C, P = 2 MPa, H₂/feed ratio of 120 NL/L, and LHSV values of 5 and 10 h− 1. The supports and catalysts were characterized by X-ray diffraction, nitrogen adsorption–desorption, scanning electron microscopy, Fourier transform infrared spectroscopy, atomic absorption spectroscopy, NH₃-temperature-programmed desorption, and thermal gravimetric analysis. The incorporation of unidirectional pore structure ZSM-23 zeolite into γ-Al₂O₃ significantly modified the catalyst’s acidity, resulting in enhanced olefin isomerization and improved octane number retention. Under optimal isomerization conditions (240 °C, LHSV of 10 h⁻¹), the composite CoMo/AZ23 catalyst achieved an isomerization percentage of 66.8%, compared to 53.3% for the conventional CoMo/γ-Al₂O₃. Consequently, under these conditions, the composite catalyst preserved fuel quality with a slight octane number increase (+ 0.1), effectively preventing the significant 2.5-unit loss associated with the conventional catalyst. This breakthrough directly enables the development of industrial hydrotreating catalysts capable of producing higher-value fuels.

Graphical abstract