Advanced solvents for CO2 separation applications

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University of Alabama Libraries

The objective of this dissertation is to advance the understanding of several novel solvents for CO2 capture and separation applications. Many of the solvents investigated were imidazole based, as these compounds are highly tunable, neutral, and less expensive analogs to imidazolium based ionic liquids (ILs). While much is known about the physical properties of ILs, the physical properties of these neutral compounds have not been researched as thoroughly, and so there is a need to explore these compounds as potential CO2 capture media. It has been further proven that the most effective means of predicting CO2 capture performance in imidazole based compounds is by examining the fractional free volume (FFV) using a molecular simulation program like COSMOTherm. Other non-imidazole based physical solvents were synthesized and compared to commercially available processes. 1,2,3-Trimethyoxypropane (1,2,3 TMP) was found to compare favorably with regard to CO2 absorption and viscosity to the current industry standard for CO2/CH4 pre-combustion separation techniques, Selexol, while being significantly less toxic. Chemical solvents for post-combustion CO2 capture were also investigated. It was determined that changing the substituents on 1-(3-aminopropyl)imidazole increases the CO2 solubility by increasing the basicity of the imidazole ring. The advantages in vapor pressure of these substituted aminopropylimidazole over traditionally used alkanolamines could potentially provide massive operational savings by reducing solvent losses through evaporation and increased solvent life.

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Chemical engineering