Efficient Synthesis of Cyclohexanol and Ethanol via the Hydrogenation of Acetic Acid-Derived Cyclohexyl Acetate with the Cu_xAl₁Mn_2−x Catalysts

The hydrogenation of cyclohexyl acetate (CHA), derived from the esterification of acetic acid and cyclohexene, not only alleviates the overcapacity of acetic acid, but also produces value-added cyclohexanol (CHOL) and ethanol at a low cost. Herein, we prepared Cu₁Al₁, Cu₁Mn₁ and Cu_xAl₁Mn_2−x catalysts via a deposition-precipitation method for the hydrogenation of CHA to CHOL and ethanol. As a result, the ternary Cu_xAl₁Mn_2−x catalysts exhibited superior behaviors to Cu₁Al₁ and Cu₁Mn₁. To our delight, Cu₁Al₁Mn₁ had a 95.0 % CHA conversion and 93.6 % selectivity to CHOL along with 97.6 % selectivity to ethanol in a batch reactor. Based on detailed characterization, the ternary Cu_xAl₁Mn_2−x catalysts possessed more uniformed dispersion of Cu particles, less aggregation and larger BET specific surface area than the binary catalysts. Furthermore, Cu₁Al₁Mn₁ possessed the highest Cu⁰/(Cu⁰+Cu⁺) molar ratio, the highest (Mn²⁺+Mn³⁺)/Mn⁴⁺ molar ratio and the most abundant surface oxygen vacancies, facilitating the adsorption and activation of CHA and hydrogen. In addition, Cu₁Al₁Mn₁ had excellent stability (>500 h) in a fixed-bed reactor.