Coupling of $$\hbox {CH}_{3}$$OH and $$\hbox {CO}_{2}$$ with 2-cyanopyridine for enhanced yields of dimethyl carbonate over $$\text {ZnO}$$–$$\text {CeO}_{2}$$ catalyst

Abstract

The present work is aimed to produce dimethyl carbonate by coupling of $$\hbox {CH}_{3}$$ OH and $$\hbox {CO}_{2}$$ with 2-cyanopyridine over ZnO– $$\text {CeO}_{2}$$ catalysts prepared by co-precipitation method. These catalysts were characterized by XRD, TEM, UV-Vis DRS, BET surface area, $$\hbox {CO}_{2}$$ and $$\hbox {NH}_{3}$$ -TPD techniques and applied for the titled reaction. Among the investigated catalysts 10ZnO–90 $$\text {CeO}_{2 }$$ catalyst with $$\text {CeO}_{2}$$ crystallite size 8.0 nm exhibited 96% conversion of methanol with 99% selectivity to dimethyl carbonate. The superior catalytic activity is a unified effect of crystalline size of $$\text {CeO}_{2}$$ and presence of an optimum number of acidic and basic sites. This protocol offers enhanced conversion of methanol with the simultaneous conversion of 2-cyanopyridine into 2-picolinamide by removing water molecules formed in the reaction. Incorporation of ZnO with $$\text {CeO}_{2}$$ enhanced the number of active sites, i.e., acidic and basic sites due to synergetic effect between ZnO and $$\text {CeO}_{2}$$ . The role of 2-cyano pyridine is to act as a dehydrating agent for the removal of $$\hbox {H}_{2}\hbox {O}$$ .