Molecular-Level Overhaul of γ-Aminopropyl Aminosilicone/Triethylene Glycol Post-Combustion CO₂-Capture Solvents

Capturing carbon dioxide from post-combustion gas streams is an energy-intensive process that is required prior to either converting or sequestering CO₂. Although a few commercial 1st and 2nd generation aqueous amine technologies have been proposed, the cost of capturing CO₂ with these technologies remains high. One approach to decrease costs of capture has been the development of water-lean solvents that aim to increase efficiency by reducing the water content in solution. Water-lean solvents, such as γ-aminopropyl aminosilicone/triethylene glycol (GAP/TEG), are promising technologies, with the potential to halve the parasitic load to a coal-fired power plant, albeit only if high solution viscosities and hydrolysis of the siloxane moieties can be mitigated. This study concerns an integrated multidisciplinary approach to overhaul the GAP/TEG solvent system at the molecular level to mitigate hydrolysis while also reducing viscosity. Cosolvents and diluents are found to have negligible effects on viscosity and are not needed. This finding allows for the design of single-component siloxane-free diamine derivatives with site-specific incorporation of selective chemical moieties for direct placement and orientation of hydrogen bonding to reduce viscosity. Ultimately, these new formulations are less susceptible to hydrolysis and exhibit up to a 98 % reduction in viscosity compared to the initial GAP/TEG formulation.