Understanding the synergy between MgO-CeO2 as an effective promoter and ionic liquids for high dimethyl carbonate production from CO2 and methanol

摘要

Direct conversion of carbon dioxide (CO2) to dimethyl carbonate (DMC) using methanol (MeOH) is an attractive approach to utilize CO2. However, this reaction is limited by low CO2 solubility and large amount water formation. For now, dehydrating agents are used to solve this problem. Our goal is to substitute to these dehydrating agents with more abundant porous metal oxide/ionic liquids (ILs) hybrid catalysts. Herein, we have prepared a glycol-based symmetrical cation with different anions assisted ILs combined with electrospun MgO-CeO2 metal oxide nanofiber sponge-500 (EMCMONS-500). The hybrid catalyst displays excellent performance towards DMC synthesis. Notably it showed 98.9% selectivity, and 73.1 mmol g(-1) cat DMC yield within 3 h reaction time, 3 MPa CO2 pressure, 120 degrees C, and 1.12 mmol catalyst loading. In addition, the catalyst shows there is no change in yield and selectivity after several recycles. Furthermore, due to a sponge-like morphology of the EMCMONS-500 catalyst, in which the creation of strong heterojunction takes place which is confirmed by electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) measurements. On the other hand, ILs give tunable acidic properties, high thermal stability, less viscosity, and low vapor pressure. Therefore, EMCMONS-500 easily mixed into ILs and form a highly porous network which gives a huge surface to volume ratios to form a nanoconfinement structure which is helpful to capture more CO2. Considering these advantages of ILs-EMCMONS-500 can be suitable catalyst for CO2 utilization.