Investigating the reaction mechanism of dimethyl carbonate synthesis through isotopic labeling experiments.

The synthesis of dimethyl carbonate (DMC) from carbon dioxide and methanol was studied over a ceria- zirconia mixed metal oxide. When using oxygen-18 labeled ceria-zirconia, no oxygen-18 labeled DMC or water was observed. On the other hand, using oxygen-18 labeled methanol led almost exclusively to the formation of double labeled DMC, CH 3 18 O (C 16 O) 18 OCH 3. These results were used to further elaborate the proposed reaction mechanisms for DMC synthesis. The rate-controlling step identified was that of a nucleophilic attack of gas phase methanol on surface monomethyl carbonate species to form DMC. [Display omitted] • Dimethyl carbonate synthesis over oxides does not follow a Mars-Van Krevelen route. • The rate controlling step is a nucleophilic attack of methanol/methoxy species. • Zirconia promotion of ceria weakens the methyl carbonate species metal‑oxygen bond. [ABSTRACT FROM AUTHOR]