Silylamine reversible ionic liquids were designed to achieve specific physical properties in order to address effective CO₂ capture. The reversible ionic liquid systems reported herein represent a class of switchable solvents where a relatively non-polar silylamine (molecular liquid) is reversibly transformed to a reversible ionic liquid (RevIL) by reaction with CO₂ (chemisorption). The RevILs can further capture additional CO₂ through physical absorption (physisorption). The effects of changes in structure on (1) the CO₂ capture capacity (chemisorption and physisorption), (2) the viscosity of the solvent systems at partial and total conversion to the ionic liquid state, (3) the energy required for reversing the CO₂ capture process, and (4) the ability to recycle the solvents systems are reported.

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Amine scrubbing is an efficient method for carbon capture and sequestration, but secondary amines present in all amine solvents can form carcinogenic nitrosamines. Decomposition kinetics for n-nitrosopiperazine (MNPZ), nitrosodiethanolamine (NDELA), and nitroso-(2-hydroxyethyl) glycine (NHeGly) were measured over a range of temperature, base concentration, base strength, and CO2 loading pertinent to amine scrubbing. MNPZ and NDELA decomposition is first order in the nitrosamine, half order in base concentration, and base-catalyzed with a Brønsted slope of β = 0.5. The activation energy is 94, 106, and 112 kJ/mol for MNPZ, NDELA, and NHeGly, respectively. MNPZ readily decomposes at 150 °C in 5 M piperazine, making thermal decomposition an important mechanism for MNPZ control. However, NHeGly and NDELA are too stable at 120 °C in 7 M monoethanolamine (MEA) for thermal decomposition to be important. Base treatment during reclaiming could rapidly and selectively decompose NHeGly and NDELA to mitigate nitrosamine accumulation in MEA.

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The Madelung energy of tetrathiafulvalenium-tetracyanoquinodimethanide (TTF-TCNQ) has been calculated as a function of assumed charge transfer, charge distribution, and temperature, using a modified Evjen summing criterion. A large, temperature-independent, Madelung energy, EM --2.3 eV/molecule (--53 kcal/mole), was calculated for the case of delocalized unit charges on the molecules. EM alone is shown to be insufficient to stabilize charge transfer in TTF-TCNQ, and the polarization energy is shown to be the most plausible source of additional energy gain upon charge transfer. The near-neighbor Coulomb interactions are evaluated and shown to be the major source of energy gain upon charge delocalization on the molecule.