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<p>The valence state ratio of Cu species (Cu<sup>+</sup>/Cu<sup>0</sup>) is struggle to precisely control in conventional preparation methods, and the structure-activity relationship between this ratio and catalytic activity remains further clarification. This study employed the coprecipitation method to prepare CuO<sub>x</sub>-ZnO-ZrO<sub>2</sub> (CZZ) catalyst precursors. Subsequently, the distribution of Cu<sup>+</sup> and Cu<sup>0</sup> species was controlled through liquid-phase reduction reactions using NaBH<sub>4</sub> at different molar ratios (0, 0.2, 0.5, 1.0 and 1.5) relative to Cu. The impact of this regulation on the physicochemical characteristics and CO<sub>2</sub> hydrogenation performance of the catalysts were systematically examined. Under reaction conditions of 240 ℃, 3&#xa0;MPa, CO<sub>2</sub> /H<sub>2</sub> = 1/3, and GHSV = 12,000 mL⋅<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:{\text{g}}_{\text{cat}}^{\text{-1}}\)</EquationSource> </InlineEquation>⋅h<sup>− 1</sup>, CZZ-0.5 displayed the optimum catalytic performance. It demonstrated superior CO<sub>2</sub> conversion compared to other samples and achieved a methanol space-time yield (STY) of 0.48 g<sub>MeOH</sub>⋅<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\:{\text{g}}_{\text{cat}}^{\text{-1}}\)</EquationSource> </InlineEquation>⋅h<sup>− 1</sup>. Detailed characterization results indicated that the CZZ-0.5 catalyst showed the minimum Cu<sup>+</sup>/Cu<sup>0</sup> ratio, the most substantial Cu dispersion, the most ideal distribution of medium-strength basic sites, and the most plentiful oxygen vacancies. Mechanistic analysis revealed that Cu<sup>0</sup> sites are in charge of the adsorption and dissociation of H<sub>2</sub>, while Cu<sup>+</sup> sites facilitate the formation of formate and its rapid conversion to methoxy species. The optimal Cu<sup>+</sup>/Cu<sup>0</sup> ratio effectively enhances methanol synthesis efficiency through the cooperative interaction between Cu<sup>+</sup> and Cu<sup>0</sup> sites.</p> Graphical Abstract <p></p>

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Elucidating the Influence of the Cu+/Cu0 Ratio in CuOx-ZnO-ZrO2 Catalyst via NaBH4 Reduction for CO2 Hydrogenation to Methanol

  • 期刊论文

  • 发表日期：

    2026年4月6日

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  • Zefeng Wang,
  • Xinrui Pi,
  • ZiLong Jiao,
  • Wei Na,
  • Min Zheng,
  • Wengui Gao

摘要

The valence state ratio of Cu species (Cu+/Cu0) is struggle to precisely control in conventional preparation methods, and the structure-activity relationship between this ratio and catalytic activity remains further clarification. This study employed the coprecipitation method to prepare CuOx-ZnO-ZrO2 (CZZ) catalyst precursors. Subsequently, the distribution of Cu+ and Cu0 species was controlled through liquid-phase reduction reactions using NaBH4 at different molar ratios (0, 0.2, 0.5, 1.0 and 1.5) relative to Cu. The impact of this regulation on the physicochemical characteristics and CO2 hydrogenation performance of the catalysts were systematically examined. Under reaction conditions of 240 ℃, 3 MPa, CO2 /H2 = 1/3, and GHSV = 12,000 mL⋅ \(\:{\text{g}}_{\text{cat}}^{\text{-1}}\) ⋅h− 1, CZZ-0.5 displayed the optimum catalytic performance. It demonstrated superior CO2 conversion compared to other samples and achieved a methanol space-time yield (STY) of 0.48 gMeOH⋅ \(\:{\text{g}}_{\text{cat}}^{\text{-1}}\) ⋅h− 1. Detailed characterization results indicated that the CZZ-0.5 catalyst showed the minimum Cu+/Cu0 ratio, the most substantial Cu dispersion, the most ideal distribution of medium-strength basic sites, and the most plentiful oxygen vacancies. Mechanistic analysis revealed that Cu0 sites are in charge of the adsorption and dissociation of H2, while Cu+ sites facilitate the formation of formate and its rapid conversion to methoxy species. The optimal Cu+/Cu0 ratio effectively enhances methanol synthesis efficiency through the cooperative interaction between Cu+ and Cu0 sites.

Graphical Abstract