Application of Copper-Based Catalysts Prepared by the Formic Acid Reduction Method in the Dehydrogenation of Sec-butanol

Abstract

Copper-based catalysts supported on ZnO and SiO₂ (Cu–ZnO and Cu–SiO₂) were prepared via a formic acid reduction method and evaluated in the dehydrogenation of sec-butanol (SBA) to methyl ethyl ketone (MEK). The catalysts were comprehensively characterized by multiple techniques, and the catalytic mechanism was elucidated in conjunction with theoretical calculations. The results demonstrate that the Cu–ZnO catalyst prepared by formic acid reduction outperforms those synthesized by impregnation and coprecipitation methods. When using the formic acid reduction method, the Cu–SiO₂ catalyst exhibits superior catalytic performance to Cu–ZnO. Characterization reveals that the SiO₂ support endows the catalyst with a larger specific surface area (101.59 m²/g) and better copper dispersion, along with a higher Cu⁰/(Cu⁺+Cu⁰) ratio (41.3%), which collectively account for the enhanced catalytic activity. With varying copper loadings (30%, 35%, and 40%), Cu–SiO₂ consistently outperforms Cu–ZnO in catalytic performance. DFT calculations indicate that the adsorption energy of SBA on the Cu–SiO₂ model is higher than that on Cu–ZnO, with the hollow site exhibiting the most pronounced adsorption (− 592,571.24 kJ/mol), thereby facilitating the dehydrogenation reaction. For MEK and atomic hydrogen adsorption, the relative energies on the Cu–ZnO model are higher than those on Cu–SiO₂. Based on the experimental results, the active sites of the Cu–SiO₂ catalyst are primarily located at the hollow sites, whereas for the Cu–ZnO catalyst, the reaction preferentially proceeds at the top sites with lower relative adsorption energy.

Graphical Abstract