Leiden Institute of Chemistry, Leiden University , P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Covestro Deutschland AG , 51365 Leverkusen, Germany.
J Am Chem Soc. 2017 Oct 18;139(41):14693-14698. doi: 10.1021/jacs.7b08208. Epub 2017 Oct 3.
In this work, we report a fundamental mechanistic study of the electrochemical oxidative carbonylation of methanol with CO for the synthesis of dimethyl carbonate on metallic electrodes at low overpotentials. For the first time, the reaction was shown to take place on the metallic catalysts without need of oxidized metals or additives. Moreover, in-situ spectroelectrochemical techniques were applied to this electrosynthesis reaction in order to reveal the reaction intermediates and to shed light into the reaction mechanism. Fourier transformed infrared spectroscopy was used with different electrode materials (Au, Pd, Pt, and Ag) to assess the effect of the electrode material on the reaction and the dependence of products and intermediates on the applied potentials. It was observed that the dimethyl carbonate is only formed when the electrode is able to decompose/oxidize MeOH to form (adsorbed) methoxy groups that can further react with CO to dimethyl carbonate. Furthermore, the electrode needs to adsorb CO not too strongly; otherwise, further reaction will be inhibited because of surface poisoning by CO.
在这项工作中，我们对甲醇在低过电势下与 CO 进行电化学氧化羰基化反应合成碳酸二甲酯的机理进行了深入研究。这是首次证明该反应在金属催化剂上进行，而不需要氧化金属或添加剂。此外，我们还将原位光谱电化学技术应用于该电合成反应，以揭示反应中间体，并阐明反应机理。我们使用傅里叶变换红外光谱法对不同的电极材料（金、钯、铂和银）进行了研究，以评估电极材料对反应的影响，以及产物和中间体对施加电势的依赖性。结果表明，只有当电极能够将甲醇分解/氧化成（吸附的）甲氧基基团，并且这些基团能够进一步与 CO 反应生成碳酸二甲酯时，碳酸二甲酯才会形成。此外，电极对 CO 的吸附不能太强，否则由于 CO 的表面中毒，进一步的反应将受到抑制。
