Enhanced Conversion in the Direct Synthesis of Diethyl Carbonate from Ethanol and CO2 by Process Intensification

To overcome the low equilibrium conversion in the direct synthesis of diethyl carbonate from ethanol and CO2 under moderate reaction conditions, the reaction was conducted in a membrane reactor packed with pelletized Cu‐Ni:3‐1 supported on activated carbon. A SiO2/γ‐Al2O3 commercial membrane and zeolite A membranes synthesized on commercial Al2O3 supports were evaluated in the membrane reactor. Although characterization of the membranes by X‐ray diffraction confirmed the presence of a zeolite A layer on the supports, gas permeation and permselectivity tests of ethanol and water evidenced some defects of the synthesized membranes. An increase in conversion with respect to a conventional packed‐bed reactor was observed in the membrane reactors prepared on Al2O3, but equilibrium conversion was not attained. However, with the commercial membrane, the ethanol conversion was higher than the equilibrium conversion. Direct synthesis of diethyl carbonate in a membrane reactor packed with Cu‐Ni:3‐1/AC was evaluated. Improved ethanol conversion to diethyl carbonate was obtained in all membrane reactors. Ethanol conversions higher than equilibrium were attained in a membrane reactor prepared with commercial SiO2/Al2O3 membrane. The enhancement of ethanol conversion resulted from H2O permeation through the membrane.