Inorganic Membrane-based Process for High Efficiency Catalytic Conversion and Product Separation in Direct Synthesis of Dimethyl Carbonate

Dimethyl carbonate (DMC) is a promising green chemical due to its simplicity, versatility, low toxicity, high polarity, low corrosivity, and biodegradability. Further, “direct synthesis” of DMC using CO2 as a reactant offers a pathway forward to effective greenhouse gas reutilization. DMC is one of the most promising organic carbonates in terms of the range of applications.The US EPA has exempted DMC under its VOC classification rules making it a viable substitute for hydrocarbon solvents such as MEK, t-butyl acetate, etc. It has been proposed for use as a fuel additive (MTBE substitute), lithium ion battery electrolyte, and a platforming chemical for higher carbonates, polyurethanes, isocyanates, and polycarbonates. However, the commercial impact of DMC has been muted with worldwide production limited to 600% enhancement in DMC yield over the equilibrium limit was demonstrated. In the NF testing, 96 to >98% DMC rejection from methanol was obtained. Membrane performance stability was demonstrated in both subsystems at the target operating temperature. With this data, an integrated MR/NR process model was developed and technoeconomic analysis was completed. The TEA demonstrated substantial savings, yielding DMC production costs below competing petroleum derived chemicals. During the Phase II program, the primary objective will be to demonstrate the integrated CME-DMC process at a pilot scale of 1 to 5 lb/hr at the target operating conditions developed in Phase I. This unit will be the basis for the Phase III commercialization scale-up. In parallel, system optimization and finished product development activities will be undertaken to further improve process economics. Utilization of CO2 captured from power plant emissions remains a significant challenge. DMC represents a significant opportunity to tap this “no cost” reactant, with a market potential of over $3 billion/year. Further, renewable chemicals will improve US security and stability by reducing dependence upon depleting fossil oil supplies from politically volatile regions.