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<p>The particle size of catalyst active components is a key factor for catalytic activity. In this work, functionalized halloysite (Hal) provides a synthetic strategy for the preparation of catalysts loaded with small Pd particles. In this study, halloysite nanotubes were employed as catalyst supports, and the ac-Hal support was synthesized via mild treatment of halloysite nanotubes with acetic acid (ac). The ac-Hal-Pd catalyst was prepared by the coprecipitation method and exhibited excellent catalytic activity for toluene oxidation, with a temperature for 90% toluene conversion (T<sub>90</sub>) of 179&#xa0;°C. Transmission electron microscopy (TEM), CO pulse chemisorption, and CO adsorption in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses revealed that the Pd particles on the surface of the ac-Hal-Pd catalyst had a smaller particle size and more uniformly dispersed Pd particles. X-ray photoelectron spectroscopy (XPS) and O<sub>2</sub>-temperature-programmed desorption (O<sub>2</sub>-TPD) analyses indicate that the reduction in the particle size of Pd particles increases the proportion of Pd<sup>0</sup> on the catalyst surface and the concentration of adsorbed oxygen, which is also a key factor for the enhancement of catalytic activity. In situ DRIFTS spectra of NH<sub>3</sub> adsorption reveal that ac-Hal-Pd possesses a higher abundance of Lewis acid sites, which is favorable for the catalytic reaction. In situ DRIFTS results suggest that toluene oxidation over ac-Hal-Pd proceeds through the formation of benzyl alcohol/alkoxy species, benzaldehyde, benzoate/benzoic acid species, and maleic anhydride intermediates, which are finally oxidized to CO<sub>2</sub> and H<sub>2</sub>O.</p>

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Controllable synthesis of small-sized Pd nanoparticles on acetic acid-modified halloysite for enhanced toluene oxidation

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月19日

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  • Haoyan Zhang,
  • Yinmin Zhang,
  • Zhifei Hao,
  • Qihang Zhao,
  • Yanbing Gong,
  • Tianjia Chen,
  • Yongfeng Zhang,
  • Quanzhi Tian,
  • Hao Sun

摘要

The particle size of catalyst active components is a key factor for catalytic activity. In this work, functionalized halloysite (Hal) provides a synthetic strategy for the preparation of catalysts loaded with small Pd particles. In this study, halloysite nanotubes were employed as catalyst supports, and the ac-Hal support was synthesized via mild treatment of halloysite nanotubes with acetic acid (ac). The ac-Hal-Pd catalyst was prepared by the coprecipitation method and exhibited excellent catalytic activity for toluene oxidation, with a temperature for 90% toluene conversion (T90) of 179 °C. Transmission electron microscopy (TEM), CO pulse chemisorption, and CO adsorption in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses revealed that the Pd particles on the surface of the ac-Hal-Pd catalyst had a smaller particle size and more uniformly dispersed Pd particles. X-ray photoelectron spectroscopy (XPS) and O2-temperature-programmed desorption (O2-TPD) analyses indicate that the reduction in the particle size of Pd particles increases the proportion of Pd0 on the catalyst surface and the concentration of adsorbed oxygen, which is also a key factor for the enhancement of catalytic activity. In situ DRIFTS spectra of NH3 adsorption reveal that ac-Hal-Pd possesses a higher abundance of Lewis acid sites, which is favorable for the catalytic reaction. In situ DRIFTS results suggest that toluene oxidation over ac-Hal-Pd proceeds through the formation of benzyl alcohol/alkoxy species, benzaldehyde, benzoate/benzoic acid species, and maleic anhydride intermediates, which are finally oxidized to CO2 and H2O.