Review for the Direct Synthesis of Dimethyl Carbonate

This review summarizes the state-of-the-art for direct synthesis of dimethyl carbonate (DMC) from carbon dioxide and methanol. In addition, conventional and alternative processes are also discussed in order to understand the advantages and disadvantages of the direct synthesis of DMC. Furthermore, the major applications of DMC are described: solvent, fuels additive, and building block for organic synthesis. The major drawbacks of the direct synthesis of DMC are the low yield and reaction rate, mostly induced by the highly stable carbon dioxide molecules. The development of novel catalyst and strategies to enhance the DMC yield – such as dehydrating agents that remove the water from the reacting mixture – are pointed out as the key solution for this route. Therefore, the main catalysts (homogeneous and heterogeneous catalysts) used so far are presented, together with the respective operating conditions and catalyst performance. The use of different dehydrating agents to increase the DMC yield is also discussed.