ZnxMg1‐xO Solid Solutions: Efficient Bifunctional Acid‐Base Catalyst for the synthesis of Methyl Ethyl Oxalate from Dimethyl Oxalate and Ethanol

Abstract ZnO‐MgO composite catalysts were prepared by the coprecipitation method and used for the synthesis of methyl ethyl oxalate (EMO) from dimethyl oxalate (DMO) and ethanol (EtOH). The results of the SEM, XRD, FT‐IR and XPS confirmed that Zn 2+ ions were incorporated into the cubic MgO lattice to form the solid solution structure over ZnO‐MgO composites catalysts with 6–18 mol% ZnO. The ZnO‐MgO composite catalysts with a solid solution structure have a large specific surface area, high medium acidic density, and medium basic density according to the results of N 2 adsorption‐desorption, pyridine‐IR (Py‐IR) and NH 3 /CO 2 temperature‐programmed desorption (NH 3 ‐TPD/CO 2 ‐TPD). The Zn x Mg 1‐x O solid solution with 18 mol% ZnO‐MgO (Zn 0.18 Mg 0.82 O) catalyst showed the highest catalytic activity with 71.98 % conversion of DMO and 67.36 % selectivity to EMO (DMO: EtOH molar ratio=1 : 2, reaction time=20 min, reaction temperature=80 °C and catalyst amount=1.5 wt%). The high catalytic activity was attributed to the solid solution structure with high medium acidic density and medium basic density. The conversion of DMO showed a positive linear correlation with the medium acidic density and medium basic density according to the correlation between catalytic activity and acidity‐basicity.