(206c) Utilization of Captured CO2 for Manufacturing Alkyl Carbonates

There are very limited uses for captured CO₂ other than enhanced oil recovery (EOR) which currently has in excess of 126 projects globally. Some of these EOR projects use 2 Mega-tonne/yr of CO₂. The Global Carbon Capture and Sequestration (CCS) Institute provides a list of current and future CO₂ storage sites not linked to EOR and highlights the challenges and costs of coordinating the development of a CO₂ transportation infrastructure. Few major industrial CO₂ generation sources (e.g. fossil electric power plants, refineries, petrochemical production, ammonia/urea manufacturing facilities, etc.) are located close to these storage sites. As a result, technologies for converting captured CO₂ to value-added products are being actively pursued.

The SBIR project focuses on techno-economic merits of utilization of captured CO₂ for manufacturing alkyl carbonates. The E3Tec project team aims to convert captured CO₂ to the simplest alkyl carbonate, dimethyl carbonate (DMC) while selectively co-producing mono-ethylene glycol (MEG). An alternate process being tested uses ammonia as a chemical carrier to produce only DMC. Heat integrated reactive distillation (HIRD) equipped with side reactors and pervaporation (PerVap) membranes is ideally suited for these complex reversible and equilibrium controlled reactions.

DMC is a high-value specialty chemical with major applications in manufacturing polycarbonate, as a low VOC solvent, in lithium-ion batteries and as an intermediate in manufacturing of polyurethane. DMC is also a possible diesel fuel additive and this application would expand the DMC market tremendously. MEG is a major commodity chemical used in polyethylene terephthalate (PET) with end-use in making films, fibers, and bottles. No single chemical product will be able to make a major impact CO₂ abatement, either by direct consumption and/or off-setting CO₂ emission for the end product. However, multiple plants from distributed CO₂ source sites will constitute a significant “wedge” in the overall CO₂ abatement target. In order for CO₂ utilization to make a major impact, commodity chemicals such as methanol and urea would need to be the products. ; However, it would be very hard to compete against these commodity chemicals, especially with low natural gas prices. Specialty chemicals, such as DMC and MEG, with favorable product margin will provide the basis for early commercialization.

Methanol is feedstock for DMC, so once the DMC technology is demonstrated, an integrated process to make DMC can be developed with CO₂ capture linked to methanol. In essence, DMC is an ideal chemical for CO₂ utilization. The economic analysis shows that high-value products, such as alkyl carbonates, would offset the costs of CO₂ capture and sequestration.