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A combined experimental and theoretical study has been carried out on the wetting and reactivity of water‐lean carbon capture solvents on the surface of common column packing materials. Paradoxically, these solvents are found to be equally able to wet hydrophobic and hydrophilic surfaces. The solvents are amphiphilic and can adapt to any interfacial environment, owing to their inherent heterogeneous (nonionic/ionic) molecular structure. Ab initio molecular dynamics indicates that these structures enable the formation of a strong adlayer on the surface of hydrophilic surfaces like oxidized steel which promotes solvent decomposition akin to hydrolysis from surface oxides and hydroxides. This decomposition passivates the surface, making it effectively hydrophobic, and the decomposed solvent promotes leaching of the iron into the bulk fluid. This study links the wetting behavior to the observed corrosion of the steels by decomposition of solvent at steel interfaces. The overall affect is strongly dependent on the chemical composition of the solvent in that amines are stable, whereas imines and alcohols are not. Moreover, plastic packing shows little to no solvent degradation, but an equal degree of wetting. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Anthropogenic CO2 emissions from point sources (e.g., coal fired-power plants) account for the majority of the greenhouse gases in the atmosphere. Water-lean solvent systems such as CO2-binding organic liquids (CO2BOLs) are being developed to reduce the energy requirement for CO2 capture. Many water-lean solvents such as CO2BOLs are currently limited by the high viscosities of concentrated electrolyte solvents, thus many of these solvents have yet to move toward commercialization. Conventional standard trial-and-error approaches for viscosity reduction, while effective, are time consuming and economically expensive. We rethink the metrics and design principles of low-viscosity CO2-capture solvents using a combined synthesis and computational modeling approach. We critically study the effects of viscosity reducing factors such as orientation of hydrogen bonding, introduction of higher degrees of freedom, and cation or anion charge solvation, and assess whether or how each factor affects viscosity of CO2BOL CO2 capture solvents. Ultimately, we found that hydrogen bond orientation and strength is the predominant factor influencing the viscosity in CO2BOL solvents. With this knowledge, a new CO2BOL variant, 1-MEIPADM-2-BOL, was synthesized and tested, resulting in a solvent that is approximately 60 % less viscous at 25 mol % CO2 loading than our base compound 1-IPADM-2-BOL. The insights gained from the current study redefine the fundamental concepts and understanding of what influences viscosity in concentrated organic CO2-capture solvents. [ABSTRACT FROM AUTHOR]

Cover Feature: Molecular-Level Overhaul of -Aminopropyl Aminosilicone/Triethylene Glycol Post-Combustion CO2-Capture Solvents (ChemSusChem 13/2020) Keywords: amines; CO2 capture; gas purification; molecular dynamics; solvents EN amines CO2 capture gas purification molecular dynamics solvents 3286 3286 1 07/09/20 20200707 NES 200707 B The Cover Feature b illustrates the approach that bridges the fundamental aspects of atomistic simulations with the design of single-components diamines for CO SB 2 sb capture. Amines, CO2 capture, CO2 capture, gas purification, molecular dynamics, solvents. [Extracted from the article]