Densities, Viscosities of Pure 1-(2-Hydroxyethyl) Pyrrolidine, 3-Amino-1-Propanol, Water, and Their Mixtures at 293.15 to 363.15 K and Atmospheric Pressure.

Densities and viscosities of pure 1-(2-hydroxyethyl) pyrrolidine, 3-amino-1-propanol, water, and their blends' data are reported from 293.15 to 363.15 K and at ambient pressure. Densities of pure water show higher values than that of 3-amino-1-propanol and 1-(2-hydroxyethyl) pyrrolidine, whereas pure 3A1P is more viscous than 1-(2-hydroxyethyl) pyrrolidine and water. The excess molar volumes and viscosity deviations from the data are correlated to the Redlich-Kister equation. The shape and value for the excess molar volumes and viscosity deviations could explain the intermolecular interaction between the molecules.

Vapor-Liquid Equilibria Data for 2-Piperidineethanol and 1-(2-Hydroxyethyl)pyrrolidine in Aqueous Solutions and a UNIQUAC Model Representation.

This work reports equilibrium data for two amines, 2-piperidineethanol (2-PPE) and 1-(2-hydroxyethyl)pyrrolidine (1-(2HE)PRLD), and their aqueous solutions. The pressure, temperature, and composition data are used to calculate experimental activities. Data cover temperatures from 363 to 426 K for the pure amines and from 323 to 373 K for the aqueous solutions. A UNIQUAC model was used to represent the binary vapor-liquid equilibria (VLE), whereas the Antoine equation was used for pure components. In an aqueous solution, the vapor pressure of 1-(2-hydroxyethyl)pyrrolidine (1-(2HE)PRLD) over the measured composition and temperature ranges is higher than that of 2-piperidineethanol (2-PPE). The developed UNIQUAC models represent the data well. For 2-piperidineethanol (2-PPE), the model gave 1.9% deviations for total pressure, 12.4% for vapor-phase composition, 12.7% for the calculated activity coefficients, and 16.2% for the excess heat capacity. In the case of 1-(2-hydroxyethyl)pyrrolidine (1-(2HE)PRLD), the model was slightly more accurate, representing the data with 1.7% deviation for total pressure, 5.9% for vapor-phase composition, and 5.2% for the calculated activity coefficient.

Solubility of Carbon Dioxide, Hydrogen Sulfide, Methane, and Nitrogen in Monoethylene Glycol; Experiments and Molecular Simulation.

Knowledge on the solubility of gases, especially carbon dioxide (CO2), in monoethylene glycol (MEG) is relevant for a number of industrial applications such as separation processes and gas hydrate prevention. In this study, the solubility of CO2 in MEG was measured experimentally at temperatures of 333.15, 353.15, and 373.15 K. Experimental data were used to validate Monte Carlo (MC) simulations. Continuous fractional component MC simulations in the osmotic ensemble were performed to compute the solubility of CO2 in MEG at the same temperatures and at pressures up to 10 bar. MC simulations were also used to study the solubility of methane (CH4), hydrogen sulfide (H2S), and nitrogen (N2) in MEG at 373.15 K. Solubilities from experiments and simulations are in good agreement at low pressures, but deviations were observed at high pressures. Henry coefficients were also computed using MC simulations and compared to experimental values. The order of solubilities of the gases in MEG at 373.15 K was computed as H2S > CO2 > CH4 > N2. Force field modifications may be required to improve the prediction of solubilities of gases in MEG at high pressures and low temperatures.

Chemical Stability and Characterization of Degradation Products of Blends of 1-(2-Hydroxyethyl)pyrrolidine and 3-Amino-1-propanol.

Aqueous amine solvents are used to capture CO2 from various flue gas sources. In this work, the chemical stability of a blend of 3-amino-1-propanol (3A1P) and 1-(2-hydroxyethyl)pyrrolidine [1-(2HE)PRLD] was studied. The chemical stability tests were conducted both in batch and cycled systems using various oxygen and NOx concentrations, additives (iron), and temperatures. In the thermal degradation experiments with CO2 present, the blend was more stable than the primary amines [(3A1P or monoethanolamine (MEA)] but less stable than the tertiary amine 1-(2HE)PRLD alone. Similar stability was observed between MEA, 3A1P, and the blend in the batch experiments at medium oxygen concentration (21% O2) and no iron present. 1-(2HE)PRLD was more stable. However, the presence of high oxygen concentration (96% O2) and iron reduced the stability of 1-(2HE)PRLD significantly. Furthermore, in the case of the blend, the chemical stability increased with increasing promoter concentration in batch experiments. During the cyclic experiment, the amine loss for the blend was similar to what was previously observed for MEA (30 wt %) under the same conditions. A thorough mapping of degradation compounds in the solvent and condensate samples resulted in the identification and quantification of 30 degradation compounds. The major components in batch and cycled experiments varied somewhat, as expected. In the cyclic experiments, the major components were ammonia, 3-(methylamino)-1-propanol (methyl-AP), N,N'-bis(3-hydroxypropyl)-urea (AP-urea), pyrrolidine, formic acid (formate), and N-(3-hydroxypropyl)-glycine (HPGly). Finally, in this paper, formation pathways for the eight degradation compounds (1,3-oxazinan-2-one, AP-urea, 3-[(3-aminopropyl)amino]-1-propanol, tetrahydro-1-(3-hydroxypropyl)-2(1H)-pyrimidinone, methyl-AP, N-(3-hydroxypropyl)-formamide, N-(3-hydroxypropyl)-ß-alanine, and HPGly) are suggested.

Impact of Solvent on the Thermal Stability of Amines.

Water-lean solvents have been proposed as a possible alternative to aqueous amine systems in postcombustion carbon capture. There is however little data available on how amine degradation is affected by different solvents. This study presents new insights on the effect of solvent on thermal degradation of alkanolamines from laboratory-scale degradation experiments. Replacing the water in aqueous monoethanolamine (MEA) solutions with organic diluents resulted in varying thermal degradation rates. Overall, all tested organic diluents (triethylene glycol, diethylene glycol, mono ethylene glycol, tetrahydrofurfuryl alcohol, N-formyl morpholine/water, and N-methyl-2-pyrrolidone) resulted in higher thermal degradation rates for loaded MEA. None of the proposed parameters, such as acid-base behavior, polarity, or relative permittivities, stood out as single contributing factors for the variation in degradation rates. The typical degradation compounds observed for an aqueous MEA solvent were also observed for MEA in various concentrations and with various organic diluents.

CO2 in Lyotropic Liquid Crystals: Phase Equilibria Behavior and Rheology.

The CO2 absorption of liquid crystalline phases of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic L92, (EO)8(PO)47(EO)8), monoethanolamine (MEA), and water, with a composition of 60% L92/10% MEA/30% water has been investigated to assess potential use in carbon capture and storage applications. Vapor⁻liquid equilibrium data of the liquid crystalline system with CO2 was recorded up to a CO2 partial pressure of 6 bar, where a loading of 38.6 g CO2/kg sample was obtained. Moreover, the phase transitions occurring during the loading process were investigated by small angle X-ray scattering (SAXS), presenting a transition from lamellar + hexagonal phase to hexagonal (at 25 °C). In addition, the rheology of samples with varying loadings was also studied, showing that the viscosity increases with increasing CO2-loading until the phase transition to hexagonal phase is completed. Finally, thermal stability experiments were performed, and revealed that L92 does not contribute to MEA degradation.