Modeling Differential Enthalpy of Absorption of CO with Piperazine as a Function of Temperature.

Temperature-dependent correlations for equilibrium constants (ln ) and heat of absorption (Δ) of different reactions (i.e., deprotonation, double deprotonation, carbamate formation, protonated carbamate formation, dicarbamate formation) involved in the piperazine (PZ)/CO/HO system have been calculated using computational chemistry based ln values input to the Gibbs-Helmholtz equation.

Understanding Carbamate Formation Reaction Thermochemistry of Amino Acids as Solvents for Postcombustion CO Capture.

The carbamate stability constant for a data set of 10 amino acids, having potential for being postcombustion CO capture (PCC) solvents, has been calculated using various implicit and explicit solvation shell models. This work also includes an extensive study of gas-phase free energy and enthalpy for the amino acid carbamate formation reaction with the Hartree Fock method, density functional methods [B3LYP/6-311++G(d,p)], and composite methods (G3MP2B3, G3MP2, CBS-QB3, and G4MP2). Ideal PCC solvent properties require finding a profitable tradeoff between various thermodynamic and system optimization parameters.

Postcombustion CO2 Capture Solvent Characterization Employing the Explicit Solvation Shell Model and Continuum Solvation Models.

Unlabelled: A study on the explicit and implicit solvation models for calculation of solvation free energy of ions and pKa of amino acids presented recently [ Gupta , M. ; J. Chem.

Theoretical study of differential enthalpy of absorption of CO2 with MEA and MDEA as a function of temperature.

Temperature dependent correlations for enthalpy of deprotonation, carbamate formation, and heat of absorption of the overall reaction between aqueous MEA and MDEA and gaseous CO2 are calculated on the basis of computational chemistry based ln K values input to the Gibbs-Helmholtz equation. Temperature dependency of reaction equilibrium constants for deprotonation and carbamate formation reactions is calculated with the SM8T continuum solvation model coupled with density functional theoretical calculations at the B3LYP/6-311++G(d,p) level of theory. Calculated reaction equilibrium constants and enthalpies of individual reactions and overall heat of absorption are compared against experimental data in the temperature range 273.

Modeling temperature dependency of ionization constants of amino acids and carboxylic acids.

The temperature sensitivity of pK(a) values for a data set of 10 amino acids and 5 carboxylic acids is studied using PCM and SM8T continuum solvation models coupled with density functional theoretical calculations at the B3LYP/6-311++G(d,p) level of theory. The data set of amino acids was chosen on the basis of their potential to be solvents for postcombustion CO2 capture processes and available literature data. Calculated results are compared with experimental data in a temperature range of 273-393 K.

Biological N removal from wastes generated from amine-based CO2 capture: case monoethanolamine.

Large-scale amine-based CO(2) capture will generate waste containing large amounts of ammonia, in addition to contaminants such as the actual amine as well as degradation products thereof. Monoethanolamine (MEA) has been a dominant amine applied so far in this context. This study reveals how biological N removal can be achieved even in systems heavily contaminated by MEA in post- as well as pre-denitrification treatment systems, elucidating the rate-limiting factors of nitrification as well as aerobic and denitrifying biodegradation of MEA.

Biodegradation of amine waste generated from post-combustion CO(2) capture in a moving bed biofilm treatment system.

Nitrogen and organic matter removal from reclaimer waste of a monoethanolamine (MEA) based CO(2)-capture plant was demonstrated in a pre-denitrification biofilm system. The reclaimer waste was generated from a 30 % (w/w) MEA solvent used for capturing CO(2) from flue gas from a coal-fired power plant. MEA, N-(2-hydroxylethyl)glycine (HEGly) and 2-hydroxyethylformamide (HEF) were the major contaminants treated.

Modeling temperature dependency of amine basicity using PCM and SM8T implicit solvation models.

PCM and SM8T continuum solvation models are used to study the temperature dependency of a set of amines in the temperature range 273-393 K using density functional theoretical calculations. Gaseous phase calculations are done using B3LYP and M06 functionals at the 6-311++G(d,p) basis set level. pK(a) values calculated computationally are compared with experimental values in the given temperature region using both continuum solvation models.

Explicitly representing the solvation shell in continuum solvent calculations.

A method is presented to explicitly represent the first solvation shell in continuum solvation calculations. Initial solvation shell geometries were generated with classical molecular dynamics simulations. Clusters consisting of solute and 5 solvent molecules were fully relaxed in quantum mechanical calculations.

NMR study and quantum mechanical calculations on the 2-[(2-aminoethyl)amino]-ethanol-H2O-CO2 system.

13C and 1H NMR spectra were obtained for AEEA (2-[(2-aminoethyl)amino]-ethanol)-H2O-CO2 systems and quantum mechanical calculations were carried out for the different AEEA species. The results suggest that the main AEEA species under the conditions studied are free amine, primary carbamate, and secondary carbamate. There is also some indication that a dicarbamate species is formed, this species does however only appear to be formed in small amounts.