390952 Effects of Contaminants to Physical Solvents for Pre-Combustion CO2 Capture
The pre-combustion capture process involves converting fossil fuel into syngas, primarily a mixture of carbon monoxide and hydrogen, usually by gasification. During pre-combustion, coal is first transformed into hydrogen and CO2. In a CO2 separation unit, the carbon dioxide is separated from the hydrogen using a solvent, such as ionic liquids (ILs). This process has the potential of capturing and removing 90 percent of CO2 emissions from power plants - major contributors to global warming.
ILs are salts with many advantages over conventional pre-combustion CO2 capture materials, including low melting points, longer lifetimes and higher stability over a range of process conditions. While ILs for CO2 capture are a popular research topic, less attention has been focused on the impact of contaminants, i.e., water and coal derived contaminants (primarily H2S), on ILs for pre-combustion carbon capture process. We explore the use of physical solvents for pre-combustion carbon capture. Four solvents have been under investigation, including PDMS, hybrid-PDMS, and two types of ILs, i.e., P888 allyl Tf2N and allyl pyridinum Tf2N, with different initial viscosity. A 1-liter Continuous Stirred Tank Reactor (CSTR) equipped with a 2-liter gas buffer tank has been used to measure CO2 isotherms and CO2 breakthrough curves at different temperatures. For CO2 solubility and kinetics measurement without contaminants, a dynamic pressure-step method was applied, while a continuous flow operation was used for CO2 breakthrough measurement in the presence of H2O and H2S. Effects of H2O and H2S on these solvents physiochemical properties will be discussed. This study has established an understanding of the influence of precombustion contaminants, i.e., H2O and H2S, on solvents physiochemical properties, including CO2 solubility, CO2 absorption kinetics, viscosity, and so on.