Grantee Research Project Results

Presently, there are no U.S. manufacturers for producing dimethyl carbonate (DMC), an environmentally benign and nonflammable solvent used in numerous applications. This strategically important solvent is used in numerous products, ranging from batteries to plastics, with most production occurring in China. DMC is a favored solvent for lithium ion batters due to its low volatility and nonflammable nature that can withstand large voltage windows and temperature excursions. Other applications for DMC include using it as an environmentally benign substitute for toxic phosgene and dimethyl sulfate in carbonylation and methylation reactions. In the manufacturing of polycarbonate, phosgene is used, which can be replaced with DMC. Current annual production of poly carbonate is 2 million tons worldwide, with an expected increase of 5 percent to 10 percent annually. DMC also is used in the synthesis of isocyanates, which are subsequently used to produce polyurethane, coating materials and insecticides. The demand for polyurethane resin was recently at 7.6 billion pounds in the United States, driven by building insulation, coatings, and adhesives.

 

Dimethyl carbonate production methods have historically involved toxic and hazardous reagents or resulted in harmful by-products. For instance, the phosgene method reacts methanol with phosgene in the presence of an aqueous alkali metal hydroxide solution and an inert water-immiscible organic solvent. These prior methods for DMC production all have suffered from low yields, the need for corrosion-resistant reactors, toxicity and explosive potentials. Additionally, these systems have required high energy consumption and high investment cost and production costs because of the requirement to separate intermediates. Consequently, there has been a push to develop one-pot or batch synthesis of DMC from carbon dioxide and methanol.

 

A greener manufacturing method is proposed by Reactive Innovations to produce DMC that will not only enable U.S. manufacturing of this important solvent, but will do so using an efficient reactor that minimizes energy and waste streams. This program will develop an electrochemical synthesis method for producing DMC from carbon dioxide and methanol feedstocks using an ionic liquid electrolyte medium. We will apply this reaction process in a microchannel electrochemical reactor that enables high production levels to be obtained continuously, unlike present electrochemical methods. This is due to the small dimensions for the flowing fluids that create overlapping boundary layers for thermal, hydraulic and mass-transfer leading to higher fluxes and, consequently, higher production throughout while minimizing waste streams.