Engineering Synergistic Cu ⁰ -Cu ⁺ -Amorphous ZrO ₂ Interfaces via Coprecipitation for Selective Ethanol-to-Ethyl Acetate Conversion

The catalytic conversion of bioethanol to ethyl acetate (EtOAc) via one-step dehydrogenative dimerization offers an economical and environmentally friendly route to obtaining valuable chemicals. This work systematically investigated the effects of the Zr/Cu ratio, calcination, and reduction temperatures on the structure and performance of coprecipitated and impregnated copper zirconium catalysts. Comprehensive characterization (XRD, HRTEM, XPS, H2-TPR, N2O chemisorption, and NH3/CO2-TPD) reveals that an intimate Cu0-Cu+-ZrO2 interfacial structure is indispensable for effective catalysis. Coprecipitation outperforms impregnation, as it fosters stronger metal–support interactions, stabilizes amorphous ZrO2 (when calcined at 400 °C), enriches the Cu+ content, and establishes balanced acid–base properties. The optimized CZ(8)cop-400 catalyst achieves a 52.8% ethyl acetate selectivity and exceptional stability under mild reaction conditions (210 °C, atmospheric pressure). In contrast, impregnated CZ(8)imp-400 exhibits higher initial activity but suffers rapid deactivation. Furthermore, calcination at 500 °C induces tetragonal ZrO2 crystallization, degrading the performance. This work demonstrates that controlled synthesis and thermal treatment critically govern interfacial nanostructure essential for efficient ethanol-to-ethyl acetate conversion.