Carbon Capture with Ionic Liquid Sorbents

Research is active on technologies for application of ionic liquids to carbon capture or other separation processes in energy systems. Two related inventions titled, "Triazolium-based Ionic Liquids as CO2 Capture Solvents and Membranes” and "Fabrication of Fiber Supported Ionic Liquids and Methods of Use” are available for licensing and/or further collaborative research from the U.S. Department of Energy’s National Energy Technology Laboratory.
Fossil fuels will be used to provide clean, affordable energy well into the 21st century, but there are concerns about impacts of greenhouse gases, particularly carbon dioxide (CO2) from fossil fuels. Capture of carbon from fossil fuel plants can produce CO2 in a concentrated stream that is amenable to geological storage. Carbon capture can be applied after fossil fuels are burned for electric power production (post-combustion capture), or in gasification plants (pre-combustion capture), where coal is converted into a clean low-carbon fuel gas that is burned in a gas turbine. However, currently available carbon capture processes significantly reduce efficiency and increase electricity cost. More efficient and economical processes for CO2 capture are needed for these applications. This invention addresses a novel class of ionic liquids (ILs) that offers promising properties for use in CO2 capture processes, as well as methods to use in applying the IL to gas separation. ILs are organic salts that are commonly liquid at room temperature. They typically have good solubility, negligible vapor pressure (reducing potential air pollution), and good thermal stability. The invention covers a class of compounds in the IL family that is based on the triazolium chemical structure (compounds containing three nitrogen atoms in a five-membered ring with two carbon atoms). The invention guides synthesis of these ILs using controllable reaction pathways resulting in compounds with a wide range of properties that are produced in good yields. Some of the resulting compounds have been shown to have improved properties over other IL classes, including increased CO2 solubility and thermal stability, facilitating their use for CO2 capture at high temperatures for high efficiency.
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