Catalytic synthesis of dimethyl carbonate from urea and methanol using SnO2 nanoplates†

SnO₂ was synthesized using precipitation method, hydrothermal method, and sol–gel combustion method. The catalysts were characterized using various physiochemical techniques like X-ray diffraction (XRD), N₂ adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS), and CO₂-temperature programmed desorption (CO₂-TPD). The catalysts were mesoporous in nature, and it was seen that the catalysts synthesized from sol–gel method (SnO₂ (S)) showed tetragonal morphology with high crystallinity. Moreover, SnO₂ (S) possessed high basicity with medium basic strength. The catalysts were further used for the synthesis of dimethyl carbonate (DMC) using urea and methanol. The study demonstrates that SnO₂ catalysts were found to be effective for the DMC synthesis through urea route. Effect of Reaction conditions were optimized, and SnO₂ (S) was found to give 51.9% DMC yield at 170 °C, 7 hours of time, with 0.2 g of the catalyst. The catalyst was easily recovered and reused, and the structure of SnO₂ was found to be intact after the reaction.