Reaction of CO₂ With Alcohols to Linear-, Cyclic-, and Poly-Carbonates Using CeO₂-Based Catalysts

Reaction of CO₂ with alcohols to organic carbonates is one of non-reductive CO₂ conversion methods. The catalysts are needed for this reaction, at the same time, effective H₂O removal methods are also needed because the yield of organic carbonates is strongly limited by the equilibrium. The development of heterogeneous catalysts for the synthesis of dimethyl carbonate from CO₂ and methanol, which is a model and typical reaction, is described. This is because heterogeneous catalysts are more suitable to the practical process than homogeneous catalysts from the viewpoint of the separation of catalysts from the products and the reusability of the catalysts. One of the reported heterogeneous catalysts is CeO₂, and it has been also reported that the combination of dimethyl carbonate synthesis from CO₂ and methanol with the hydration of nitriles such as 2-cyanopyridine, where both reactions are catalyzed by CeO₂, enabled high yield of the carbonate. In addition, the combination of CeO₂ catalyst + nitriles can be applied to the synthesis of a variety of linear-, cyclic (five- and six-membered ring)-, and poly-carbonates from CO₂ and corresponding alcohols.