(106a) CO2 Capture Using Nanoparticle Ionic Materials and Task-Specific Ionic Liquids

Since the industrial revolution in the late 18th and early 19th century, the amount of CO2 in the atmosphere has risen from 280 ppm in 1800 to 370 ppm in 2000, mainly due to the consumption of fossil fuels. Unfortunately, CO2 is one of the greenhouse gases that are considered to be responsible for global warming. Potential effects of global warming include sea level rises caused by the melting of glaciers and ice caps, increased frequency and intensity of precipitation and severe weather, poor agricultural yields, and species extinction due to the environmental changes. Moreover, the increased atmospheric CO2 concentration will acidify the ocean and will change the chemistry of the surface ocean. Once the shift in the oceanic chemical balance becomes significant, it will affect the ecosystems.

A number of CO2 capture and storage technologies are currently being developed to meet this challenge. For example, amine-based solvents such as monoethnolamine (MEA) and chilled ammonia are already being implemented for the CO2 separation from the post-combustion flue gas stream. These solvents have very high capacity to capture CO2, however they have some drawbacks including high vapor pressure, which leads to fugitive emissions during regeneration. MEA is also corrosive in nature, and thus, only dilute solution of MEA can be used for CO2 capture.

In order to overcome the shortcomings faced by amine-based solvent technologies, a novel carbon capture technology utilizing an amine-functionalized Task-Specific Ionic Liquid (TSIL) has been developed. Molecular ILs are made by pairing an asymmetric organic cation (e.g., dialkylimida-zolium or alkylpyridinium) with an inorganic anion (e.g. hexafluorophosphate) or an organic anion (e.g alkylsulfates). A high operating temperature is important for the economic feasibility of any CO2 separation technologies developed for industrial processes, and unlike conventional organic solvents that require ambient or lower operating temperatures, ILs are often non-volatile and stable over a very wide temperature range (-40 to > 300 ºC).

This study focuses on the development of CO2 capture fluids based on the nanoparticle ionic materials (NIMS) and TSILs. Their absorption isotherms are investigated as a function of CO2 partial pressure and temperature (i.e., combustion and gasification conditions). The effects of the volume fraction of nanoparticles and the different functional groups on the CO2 capture efficiencies of NIMS are also investigated. The experiments are carried out using a high-pressure high-temperature reactor setup and a micro balance system. The NIMS results are then compared with those for the commercially available ILs as well as MEA solvent, in order to optimize the design of NIMS for the maximum CO2 capture.