Electrochemical synthesis of dimethyl carbonate from methanol, CO₂ and propylene oxide in an ionic liquid

Abstract

BACKGROUND: Dimethyl carbonate (DMC) can be used effectively as an environmentally benign substitute for highly toxic phosgene and dimethyl sulfate in carbonylation and methylation, as well as a promising octane booster owing to its high oxygen content. Two-step transesterification from epoxide, methanol, and CO 2 is widely used in the bulk production of DMC. However, major disadvantages of this process are high energy consumption, and high investment and production costs. A one pot synthesis of DMC from carbon dioxide, methanol, and epoxide was, therefore, developed. But the yields of DMC are below 70% due to the thermodynamic limitation.

CO2electro-valorization to dimethyl carbonate from methanol using potassium methoxide and the ionic liquid [bmim][Br] in a filter-press electrochemical cell

“…In the past few years, the electrosynthesis of cyclic carbonates from epoxides and diols, and the production of organic carbamates from amines have been reported using ILs. The synthesis of dimethyl carbonate in the presence of ILs has also been the focus of special attention in the electrochemical field with Zhang et al and Feng and Liu, respectively, achieving 74 and 72% yields in the presence of [bmim][BF4] with a copper working electrode. To improve the yield in the same ionic liquid Feng et al and Wang et al used a nanoporous copper electrode based on platinum (NPC‐Pt) and silver (NPC‐Ag), slightly increasing the yield to 81 and 80%, respectively.…”

“…However, all these cited works achieved a high yield at the expense of using methyl iodide as additive, known to be a category 2 carcinogen. Yan et al also attained a 76% avoiding CH 3 I addition and using a platinum electrode in the presence of a different ionic liquid ([bmim][Br]). However, they used propylene oxide, which is also a category 2 carcinogen.…”

Progress in electrochemical catalytic conversion of CO<sub>2</sub> modulated by ionic liquids

“…虽然这简化产物的分 离过程, 但是该体系只获得了3.9%的收率. Cai课题 组 [31] 进一步研究发现, 以环氧丙烷代替甲醇钾, 可 以获得75.5%的收率. Liu课题组 [32,33] 通过电镀的方式 将Pt或者Ag修饰到纳米多孔铜的内表面, 以它们为 电极, 在BMIMBF 4 中通过电化学还原CO 2 制备了碳 酸二甲酯, 分别获得81%和80%的收率.…”

Electrosynthesis of dimethyl carbonate from methanol and CO2 using potassium methoxide and the ionic liquid [bmim][Br] in a filter‐press cell: a study of the influence of cell configuration

“…At the same time, it has been suggested that the electricity required for CO 2 electrochemical valorization processes may be provided by renewable sources, serving as an attractive future way of storing the intermittent and difficult to predict renewable energy as chemical energy . Several published studies report the electrosynthesis of DMC from CO 2 in the presence of ionic liquids (ILs) under mild conditions . ILs are salts characterized by negligible vapour pressure, high conductivity and a wide electrochemical window, and have attracted much attention as substitutes for conventional toxic and volatile solvents.…”

“…However, most of the cited references achieved high yields owing to the addition as a reaction promoter of methyl iodide, which is a category 2 carcinogen. Others workers avoided the addition of methyl iodide at the expense of using other toxic compounds such as propylene oxide or benzyl chloride . Although all the works cited previously used an undivided electrochemical cell, this type of cell does not allow study of the development of the process with separated anodic and cathodic compartments.…”