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<p>Developing highly efficient Pd-based catalysts with low Pd loading and ultrahigh atomic utilization efficiency remains a significant challenge in the selective hydrogenation of phenol to cyclohexanone. Herein, a dual-site catalyst incorporating both Pd single atoms (SAs) and Pd clusters on TiO<sub>2</sub> was successfully developed via atomic layer deposition (ALD). The size distribution of Pd clusters can be modulated by precise control of the Pd ALD cycles. The 0.6 wt.% Pd/TiO<sub>2</sub> catalyst synthesized with 9 Pd ALD cycles demonstrated optimal hydrogenation performance, achieving complete phenol conversion and 99% selectivity under mild conditions. Various characterization and theoretical calculations reveal that the optimal cluster size controlled by varying the number of Pd ALD cycles, modulates the electron density of adjacent Pd SAs. This electronic tuning regulates the adsorption properties of phenol and cyclohexanone. Pd SAs exclusively activate phenol, while clusters facilitate H<sub>2</sub> activation and hydrogen spillover, thus achieving optimal catalytic performance through the synergy between Pd SAs and clusters. Critically, weak adsorption of cyclohexanone on Pd SAs prevents its excessive hydrogenation. Conversely, excessively large clusters overly enhance the electron density of adjacent Pd SAs, weakening phenol adsorption at Pd SAs and promoting phenol adsorption on clusters. This disrupts the synergy between Pd SAs and clusters, leading to excessive hydrogenation. This study demonstrates the critical importance of synergistic effect between active sites in enhancing reaction efficiency, providing a solution to develop highly efficient atomically dispersed catalysts.</p>

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Rational regulation of palladium dual active sites for highly efficient hydrogenation of phenol

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • Menghao Xu,
  • Jiawen Yang,
  • Linlin Xian,
  • Chaoqiu Chen,
  • Panzhe Qiao,
  • Jiankang Zhang,
  • Xixi Zhang,
  • Conghui Wang,
  • Shichao Zhao,
  • Yong Qin

摘要

Developing highly efficient Pd-based catalysts with low Pd loading and ultrahigh atomic utilization efficiency remains a significant challenge in the selective hydrogenation of phenol to cyclohexanone. Herein, a dual-site catalyst incorporating both Pd single atoms (SAs) and Pd clusters on TiO2 was successfully developed via atomic layer deposition (ALD). The size distribution of Pd clusters can be modulated by precise control of the Pd ALD cycles. The 0.6 wt.% Pd/TiO2 catalyst synthesized with 9 Pd ALD cycles demonstrated optimal hydrogenation performance, achieving complete phenol conversion and 99% selectivity under mild conditions. Various characterization and theoretical calculations reveal that the optimal cluster size controlled by varying the number of Pd ALD cycles, modulates the electron density of adjacent Pd SAs. This electronic tuning regulates the adsorption properties of phenol and cyclohexanone. Pd SAs exclusively activate phenol, while clusters facilitate H2 activation and hydrogen spillover, thus achieving optimal catalytic performance through the synergy between Pd SAs and clusters. Critically, weak adsorption of cyclohexanone on Pd SAs prevents its excessive hydrogenation. Conversely, excessively large clusters overly enhance the electron density of adjacent Pd SAs, weakening phenol adsorption at Pd SAs and promoting phenol adsorption on clusters. This disrupts the synergy between Pd SAs and clusters, leading to excessive hydrogenation. This study demonstrates the critical importance of synergistic effect between active sites in enhancing reaction efficiency, providing a solution to develop highly efficient atomically dispersed catalysts.