Effects of surface acid–base properties of ZrO2 on the direct synthesis of DMC from CO2 and methanol: A combined DFT and experimental study

Abstract

ZrO2 is known as a prospective catalyst for the direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol, which is important for CO2 utilization and green chemicals production. To identify the relationship between catalytic activity and surface acid–base properties, here, hydroxylated tetragonal (t) and monoclinic (m) zirconia are explored using density function theory (DFT) calculations combined with catalytic activity tests, as well as various characterization techniques, including in situ Fourier transform infrared (FTIR) spectra and temperature-programmed desorption of CO2 and NH3. DMC is formed from the combination of methyl and methyl carbonates on both catalysts, and m-ZrO2 exhibits higher DMC yield than t-ZrO2. The amount and strength of surface Brønsted acid sites, rather than Lewis base sites and Lewis acid sites, strongly affect catalytic performance of ZrO2. In addition, compared with t-ZrO2, m-ZrO2 displays a smaller band gap which also facilitates its catalytic activity for DMC synthesis.