Synergy between different morphology ZnO/Cu and their effects on isopropyl acetatehydrogenation

Plate and rod-like hexagonal ZnO crystals were synthesized via a facile solution by adjusting precursor concentration. Crystal structure, growth habit and synergy between Cu and different morphology ZnO were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra and H₂ temperature-programmed reduction (H₂-TPR). The results show that ZnO crystals are elongated along the length axis and the plane diameter is reduced with the decrease of precursor concentration, which leads to morphology evolution from hexagonal plate to prismatic rod. The resulted ZnO crystals were used as a co-catalyst of copper for isopropyl acetate hydrogenation to prepare ethanol and isopropanol. The results indicate that ZnO morphology have a significant impact on isopropyl acetate hydrogenation. The Plate-like Cu/ZnO-a catalyst has the highest isopropyl acetate conversion rate and selectivity. A linear relationship between the percentage of polar plane surface area and conversion rate is identified. The isopropyl acetate conversion rate increases with the increase of polar surface percentage, which is because higher polar surface ratio of ZnO can lead to stronger interaction between ZnO and Cu. Moreover, the active component (copper) is better dispersed and easier to be reduced, which results in better catalytic hydrogenation performance.