Anti-Foaming Study for 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 physical solvent, such as commercial Selexol solvent. This process has the potential of capturing and removing 90 percent of CO₂emissions from power plants - major contributors to global warming.

We previously explore the use of hydrophobic physical solvent, hybrid-PDMS, for pre-combustion carbon capture.   Solvent showed compatible CO₂ solubility to Selexol at different operating conditions. However, foaming issue prevent its use for pre-combustion carbon capture.    To solvent this problem, we investigated adding a none-volatile ionic liquid, allyl pyridinum Tf₂N, in hybrid-PDMS. A 1-liter Continuous Stirred Tank Reactor (CSTR) equipped with a 2-liter gas buffer tank has been used to measure CO₂, H₂, and CH₄isotherms at different temperatures. For gas solubility measurement, a dynamic pressure-step method was applied.

This study has established an understanding of the influence of second non-volatile solvent on hybrid-PDMS solvent physiochemical properties, including foaming, gas solubility, CO₂ selectivity, viscosity, and so on.