Tailoring Cu-Based Catalysts Supported on ZrO2-Al2O3 for Efficient and Selective Ethanol Conversion to Ethyl Acetate.

Selective conversion of ethanol to ethyl acetate is of significant industrial and environmental relevance, providing a sustainable route for adding value to ethanol. This study investigated Cu-based catalysts supported on ZrO2-Al2O3, focusing on the relationships among copper loading, metal-oxide interactions, and catalytic performance. Systematic variation of the copper content revealed that the Cu+/Cu0 ratio and the particle size distribution are crucial determinants of product selectivity. Lower copper loadings favored acetaldehyde production due to a higher Cu+/Cu0 ratio, while higher loadings favored Cu0 species and enhanced ethyl acetate selectivity by facilitating the formation of acyl species at the metal-oxide interface. The incorporation of ZrO2 was important for the creation of active sites necessary for condensation reactions. Advanced characterization techniques ((diffuse reflectance infrared Fourier transform spectroscopy DRIFTS)-CO, X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS)) elucidated key electronic and structural properties, showing the need to tailor the copper loading and the composition of the support to ensure efficient and sustainable ethanol conversion.