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<p>The petroleum refining industry uses catalysts containing molybdenum for mild hydrogenation processes. The amount of wasted catalyst produced by these catalytic processes is enormous. Molybdenum (Mo), nickel (Ni), and cobalt (Co) are the main valuable metals in Mo spent catalysts (SC), usually being supported on Al<sub>2</sub>O<sub>3</sub>. As environmental consciousness and the demand for metal values expand, catalysts may be used as additional sources for metal recovery; however, a cost-effective and efficient method is still challenging. This study developed an efficient procedure for Mo recovery from waste Mo/alumina catalyst as a value-added material. Spent catalyst was leached with HCl acid, and the impact of various parameters, including the temperature, solid/liquid ratio, time, and acid concentration, on the Mo and Al recovery was investigated. Leaching kinetics were explored using the shrinking core model (SCM) and Avrami model, revealing that the process is mainly controlled by product layer diffusion. From the leaching solutions, Mo-based materials were prepared via a solvothermal method in mild pressure (MoS<sub>2</sub>-R) and high pressure (MoS<sub>2</sub>-A) conditions. The MoS<sub>2</sub>-A sample was calcined at 800&#xa0;°C under argon to give a more crystalline structure (MoS<sub>2</sub>-C), and the Al impurity in the leaching solution was removed using ammonia buffer to prepare pure MoS<sub>2</sub> (96%), which was then calcined to give a more crystalline structure (MoS<sub>2</sub>-C2). The synthesized materials exhibited structures with varying crystallinity, morphology, and surface properties, which play a critical role in their photocatalytic hydrogen evolution performance. These value-added materials were investigated as photocatalysts for the hydrogen evolution reaction (HER). MoS<sub>2</sub>-R gave a superior yield of 273.7&#xa0;mmol·h<sup>−1</sup>·g<sup>−1</sup>, while MoS<sub>2</sub>-A, MoS<sub>2</sub>-C, and MoS<sub>2</sub>-C2 displayed values of 241.3&#xa0;mmol·h<sup>−1</sup>·g<sup>−1</sup>, 226.1&#xa0;mmol·h<sup>−1</sup>·g<sup>−1</sup>, 207.4&#xa0;mmol·h<sup>−1</sup>·g<sup>−1</sup>, respectively. The yield of the HER is clearly reduced by enhancing the crystallinity. The findings of the study present innovative viewpoints and ideas for further research into renewable energy and waste-derived resources.</p> Graphical Abstract <p></p>

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Sustainable Valorization of HDS Spent Catalyst into MoS2-Based Materials for Photocatalytic Hydrogen Generation

  • 期刊论文

  • 发表日期：

    2026年5月3日

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  • Atef S. Hindawi,
  • Rafat Tahawy,
  • Muhammad A. Abo El-Khair,
  • Asmaa S. Morshedy,
  • Sabah. M. Abdelbasir,
  • Hosny Ibrahim

摘要

The petroleum refining industry uses catalysts containing molybdenum for mild hydrogenation processes. The amount of wasted catalyst produced by these catalytic processes is enormous. Molybdenum (Mo), nickel (Ni), and cobalt (Co) are the main valuable metals in Mo spent catalysts (SC), usually being supported on Al2O3. As environmental consciousness and the demand for metal values expand, catalysts may be used as additional sources for metal recovery; however, a cost-effective and efficient method is still challenging. This study developed an efficient procedure for Mo recovery from waste Mo/alumina catalyst as a value-added material. Spent catalyst was leached with HCl acid, and the impact of various parameters, including the temperature, solid/liquid ratio, time, and acid concentration, on the Mo and Al recovery was investigated. Leaching kinetics were explored using the shrinking core model (SCM) and Avrami model, revealing that the process is mainly controlled by product layer diffusion. From the leaching solutions, Mo-based materials were prepared via a solvothermal method in mild pressure (MoS2-R) and high pressure (MoS2-A) conditions. The MoS2-A sample was calcined at 800 °C under argon to give a more crystalline structure (MoS2-C), and the Al impurity in the leaching solution was removed using ammonia buffer to prepare pure MoS2 (96%), which was then calcined to give a more crystalline structure (MoS2-C2). The synthesized materials exhibited structures with varying crystallinity, morphology, and surface properties, which play a critical role in their photocatalytic hydrogen evolution performance. These value-added materials were investigated as photocatalysts for the hydrogen evolution reaction (HER). MoS2-R gave a superior yield of 273.7 mmol·h−1·g−1, while MoS2-A, MoS2-C, and MoS2-C2 displayed values of 241.3 mmol·h−1·g−1, 226.1 mmol·h−1·g−1, 207.4 mmol·h−1·g−1, respectively. The yield of the HER is clearly reduced by enhancing the crystallinity. The findings of the study present innovative viewpoints and ideas for further research into renewable energy and waste-derived resources.

Graphical Abstract