摘要
The direct conversion of CO 2 with methanol into dimethyl carbonate (DMC) has received considerable attention as the sustainable development process for conventional routes. The CeO 2 -based catalysts owing to suitable acid-base sites were regarded as the promising catalysts. However, the process has been hindered mainly due to the difficulty in simultaneously regulating the appropriate acid-base properties on CeO 2 -based catalysts, as well as thermodynamic limitations of generating by-product water. In this work, by virtue of enhancing interaction between active components and supports, the highly efficient CeO 2 /Beta catalysts (CeO 2 /Beta-E) were prepared by ethanol as impregnation solvents to DMC synthesis. Meanwhile, the synergistic promoting catalytic systems of DMC synthesis from CO 2 with methanol was proposed. On one hand, the content and electronic properties of oxygen vacancies and Ce 3 + species were regulated to achieve the balance between suitable acid and base sites by ethanol as impregnation solvents. Furthermore, the desired intermediates of bidentate carbonates derived from activated CO 2 on oxygen vacancies and consecutive methoxy species originated from methanol on Ce 3+ species could be markedly promoted by reconstructed surface acid-base properties of CeO 2 /Beta catalysts. Notably, methanol could be rapidly converted to intermediate species over CeO 2 /Beta-E catalysts, which was the crucial step for activation. On the other hand, it was revealed the nature of continuous removal of by-product water into the reaction solution phase to enhance thermodynamic driving forces over CeO 2 /Beta-E catalysts. Consequently, CeO 2 /Beta-E catalysts delivered a DMC yield of 38.4 mmol/g with > 99 % selectivity and excellent cycling stability, providing theoretical insights and practical guidance for designing efficient catalysts for DMC synthesis from CO 2 with methanol.
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