Structure and Thermochemistry of Phase-Changing Aminosilicone-Based CO2-Capture Absorbents

Liquid aminosilicone-based CO₂ absorbents that solidify upon reaction with CO₂ have been developed. These phase-changing absorbents have the potential for superior performance for capturing CO₂ from the flue gas of pulverized-coal power plants. A process has been conceived in which the liquid aminosilicones are reacted with the CO_2­­ in flue gas using a spray column. The solid CO₂-rich powders that form are then collected and sent to a desorber where the powder is heated, releasing high-purity CO₂ and regenerating the liquid aminosilicone, which is recycled back to the spray column. Compared to a conventional monoethanol amine-based CO₂-capture process, phase-changing absorbents have potentially higher CO₂ capacity, greater thermal stability, and simplified separations, due to their low volatility. Studies have been performed to evaluate the particle sizes and morphologies of the solid powders formed in a spray column when these materials are reacted with the CO₂ in simulated flue gas. The crystalline structure of these materials has been studied, and thermochemical methods have been used to study the absorption and desorption of CO₂.