Synergism from interfaces between Cu and crystalline ZrO2 nanosheets fabricated by acetic complex method for oxalates hydrogenation

Abstract

Herein, the Cu species uniformly combining with highly crystalline ZrO2 nanosheets had been prepared by a one-pot acetic complex method. The selectivity to ethylene glycol of 98.9%, which corresponds to 99.8% conversion of diethyl oxalate was obtained over the one prepared by using acetic acid (AC) both as the complex agent and solvent. In addition, a stable performance was achieved (life span of >160h). It also showed good performance in hydrogenation of dimethyl oxalate (95.7h−1 turnover frequency). Essentially, solvents with different dielectric constant employed in complexation process had a prominent influence on the structure and catalytic activity of Cu/ZrO2 catalyst via solvation. Besides, complexation process was also important since AC could be regarded as L-type ligands in a low dielectric constant solvent, forming of ion-clusters which resulted in exclusive formation of the Cu-O-Zr interface after calcination. Evidently, the surface synergistic effect held the key to the continuous hydrogenation reaction related to the activation of the carbonyl groups and the hydrogen dissociation, thus creating a synergetic nanoenvironment for the successful completion of the “multi step turning into one-step” in the series reaction.