High-entropy oxide-derived Cu catalysts for the coupling reaction of cyclohexanol dehydrogenation with acetone hydrogenation

Abstract

Dehydrogenation of cyclohexanol to cyclohexanone is a vital step in manufacturing nylon; however, this endothermic reaction is unfavourable at low temperatures. In this work, a high-entropy oxide (Cu_0.75Zn_0.15Mg_7.1Al₁Sc₁O₁₁-HEO) was synthesized from a well-structured Cu_0.75Zn_0.15Mg_7.1Al₁Sc₁(OH)₂₀CO₃ layered double hydroxide. Characterization results disclosed that Cu_0.75Zn_0.15Mg_7.1Al₁Sc₁O₁₁-HEO possesses a large specific surface area (157 m² g⁻¹), enhanced basicity and high Cu dispersion in the framework of HEO (74.0%). The reduced Cu_0.75Zn_0.15Mg_7.1Al₁Sc₁O₁₁-HEO catalyst was highly active and stable in the dehydrogenation of cyclohexanol compared with Cu-based catalysts prepared using binary, ternary, and quaternary mixed metal oxides. More interestingly, the conversion of cyclohexanol could be enhanced when acetone was used as the solvent and/or hydrogen acceptor. Thus, it was confirmed that the addition of acetone can enhance the yield of cyclohexanone and simultaneously result in the hydrogenation of acetone to isopropanol.