Mass Fractions Of MDEA Research Articles

Surface Thermodynamics, Viscosity, Activation Energy of N-Methyldiethanolamine Aqueous Solutions Promoted by Tetramethylammonium Arginate

The surface tension and viscosity values of N-methyldiethanolamine (MDEA) aqueous solutions promoted by tetramethylammonium arginate ([N1111][Arg]) were measured and modeled. The experimental temperatures were 303.2 to 323.2 K. The mass fractions of MDEA (wMDEA) and [N1111][Arg] (w[N1111][Arg]) were 0.300 to 0.500 and 0.025 to 0.075, respectively. The measured surface tension and viscosity values were satisfactorily fitted to thermodynamic models. With the aid of experimentally viscosity data, the activation energy (Ea) and H2S diffusion coefficient (DH2S) of MDEA-[N1111][Arg] aqueous solution were deduced. The surface entropy and surface enthalpy of the solutions were calculated using the fitted model of the surface tension. The quantitative relationship between the calculated values (surface tension, surface entropy, surface enthalpy, viscosity, activation energy, and H2S diffusion coefficient) and the operation conditions (mass fraction and temperature) was demonstrated.

Corrosion Behavior of Carbon Steel in Carbonated MDEA-MEA Aqueous Solutions

In order to deal with the long-term corrosion problems in the absorption of carbon dioxide (CO2) using alkylol amines, perfecting the corrosion parameters is necessary. The tafel curves of carbon steel in carbonated N-methyldiethanolamine (MDEA)-monoethanolamine (MEA) aqueous solutions were investigated by using the CHI602E electrochemical analyzer. Then the corresponding corrosion rates were calculated. The temperatures ranged from 303.2K to 323.2K. The mass fractions of MDEA and MEA respectively ranged from 0.30 to 0.40 and 0-0.10. The CO2 loading ranged from 0.1 to 0.4. The effects of temperatures, mass fractions and CO2 loadings on the corrosion rates were demonstrated. Results showed that corrosion rates increase with increasing temperatures, mass fractions and CO2 loadings. Moreover, the corrosion rates of carbon steel in carbonated MDEA-MEA aqueous solutions are obviously less than the corrosion rates in pure MDEA.

Study on the Viscosities of MDEA-Amino Acid Ionic Liquid Aqueous Solutions

The viscosities of 1-butyl-3-methylimidazolium glycine ([Bmim][Gly])-N-methyldiethanolamine (MDEA), tetramethyl amine glycine ([N1111] [Gly])-MDEA and l-butyl-3-methyl-imidazolium lysine ([Bmim][Lys])-MDEA aqueous solutions were respectively measured by using the NDJ-5S digital rotational viscometer. The temperatures ranged from 303.2K to 323.2K. The mass fractions of MDEA and amino acid ionic liquids (AAILs) respectively ranged from 0.30 to 0.45 and 0.05 to 0.15. The Weiland equation was used to correlate and predict the viscosities of [Bmim][Gly]-MDEA, [N1111] [Gly]-MDEA and [Bmim][Lys]-MDEA aqueous solutions. The temperature and mass fraction dependences of the viscosity of MDEA-AAIL aqueous solutions were demonstrated on the basis of experiments and calculations.

Polarization behavior of carbon steel in the CO2-[N1111][Lys]-MDEA aqueous solutions

Polarization behavior of carbon steel in the CO2 absorption process using tetramethylammoniumlysinate ([N1111][Lys]) promoted N-methyldiethanolamine (MDEA) aqueous solutions as absorbents was investigated at the temperatures ranging from 303.2K to 323.2K. The mass fractions of MDEA and [N1111][Lys] respectively ranged from 0.3 to 0.4 and 0 to 0.15. The effects of temperature and mass fractions of [N1111][Lys] on the polarization behavior were elucidated.

Solubility of low partial pressure H2S in MDEA-PZ aqueous solution

The solubility of hydrogen sulfide (H2S) in piperazine (PZ) promoted N-methyldiethanolamine (MDEA) aqueous solution was investigated. The temperature ranged from 303.2K to 323.2k. The mass fraction of MDEA and PZ respectively ranged from 0.3 to 0.4 and 0 to 0.075. On the basis of experimental measurement, the effects of mass fraction and temperature on the solubility of H2S in PZ-MDEA aqueous solution are illustrated.

CO2 removal in tray tower by using AAILs activated MDEA aqueous solution

A tray tower was designed to verify the absorption performance of CO2 in 1-butyl-3-methylimidazolium glycinate ([Bmim][Gly]), 1-butyl-3-methylimidazolium lysinate ([Bmim][Lys]) and tetramethylammonium glycinate ([N1111][Gly]) activated MDEA (N-methyldiethanolamine) aqueous solutions. The simulated flue gas was composed of 15% (mole fraction) CO2 and 85% N2 and the experiments were performed at 313.2 K. To find a suitable absorbent composition, the mass fractions of MDEA and amino acid ionic liquids (AAILs) respectively ranged from 0.200 to 0.400 and 0.025 to 0.100. The removal efficiency of CO2 (ηCO2) and the overall volumetric mass transfer coefficient (KGav) were determined. The effects of absorbent composition (w), absorbent flow rate (L), gas flow rate (G) and plate number (Np) on ηCO2 and KGav were demonstrated. Our results showed that, when activated by AAILs, MDEA aqueous solution was able to absorb CO2 in tray tower efficiently, and both ηCO2 and KGav were significantly increased, e.g., in the case of wMDEA = 0.200, ηCO2 and KGav were increased from 43.48% to 95.55% and from 0.0069 (kmol m−3 h−1·kPa−1) to 0.0350 (kmol m−3 h−1·kPa−1), respectively, when w[N1111][Gly] was changed from 0 to 0.100, indicating AAILs activated MDEA aqueous solution is of great potential for industrial application in CO2 capture process.

Absorption performance of (CO2 + N2) gas mixtures in amino acid ionic liquids promoted N-methyldiethanolamine aqueous solutions

Amino acid ionic liquids (AAILs) including 1-butyl-3-methylimidazolium glycinate ([Bmim][Gly]), 1-butyl-3-methylimidazolium L-lysinate ([Bmim][Lys]) and tetramethylammonium glycinate ([N1111][Gly]) were used to enhance the absorption of CO2 in N-methyldiethanolamine (MDEA) aqueous solutions. The mole fractions of CO2 in N2+CO2 gas mixtures ranged from 0.2 to 1.0. The mass fractions of MDEA and AAILs respectively ranged from 0.300 to 0.400 and 0.050 to 0.100. The absorption capacity and absorption rate under series of conditions were presented and the influences of CO2 partial pressure and the types of AAILs on the absorption performance were demonstrated.

Study on the surface tensions of MDEA-methanol aqueous solutions

The surface tensions (γ) of N-methyldiethanolamine (MDEA)-methanol (MeOH) aqueous solutions were measured by using an automatic surface tension-meter (BZY-1). The temperature ranged from 303.2K to 323.2K. The mass fractions of MeOH and MDEA respectively ranged from 0.05 to 0.15 and 0.2 to 0.4. On the basis of the experimental measurement, the effects of temperature and mass fraction of MDEA and MeOH on surface tensions were analyzed.

Study on viscosity of MDEA-MeOH aqueous solutions

The viscosities of the N-methyldiethanolamine (MDEA)-methanol (MeOH) aqueous solutions were measured at temperatures ranging from (303.2 to 323.2) K. The mass fraction of MDEA and MeOH respectively ranged from 0.2 to 0.4 and 0 to 0.15. On the basis of experimental measurement, the effects of temperature, mass fraction of MDEA and MeOH on viscosities were demonstrated.

Absorption performance of CO2 in high concentrated [Bmim][Lys]-MDEA aqueous solution

The absorption performance of CO2 in 1-butyl-3-methylimidazolium lysinate ([Bmim][Lys]) promoted N-methyldiethanolamine (MDEA) aqueous solution was investigated at the temperatures ranging from 303.2 K to 323.2 K. The mass fractions of MDEA and [Bmim][Lys] respectively ranged from 0.3 to 0.45 and 0.05 to 0.15. The viscosities of CO2-unloaded and CO2-loaded MDEA-[Bmim][Lys] aqueous solutions were measured and modeled. The influences of temperature and concentration on the absorption capacity of CO2 were determined. The effects of temperature, solution concentration and solution viscosity on the absorption rate were illustrated.

Online NMR Spectroscopic Study of Species Distribution in MDEA−H2O−CO2 and MDEA−PIP−H2O−CO2

Quantitative online nuclear magnetic resonance (NMR) spectroscopy was used to study the species distribution in solutions of carbon dioxide (CO 2 ) in aqueous N-methyldiethanolamine (MDEA), and MDEA + piperazine (PIP). The mass fraction of MDEA in the unloaded ternary solution was 0.2, 0.3, and 0.4 g/g. In quaternary solutions, the mass fraction of MDEA was 0.3 g/g, and that of PIP was 0.1 g/g. The temperature ranged from 293 K to 333 K, and the overall CO 2 loading was up to 1.4 molco 2 /mol amine. For the measurements, a special apparatus was used that allowed the mixtures to be prepared gravimetrically and applied pressures up to 25 bar to keep the CO 2 in solution. It was coupled to a 400 MHz NMR spectrometer by heated capillaries. Using both 1 H and 13 C NMR spectroscopy, quantitative information on the concentrations of the following species was obtained: amines, carbamates, bicarbonate, and CO 2 . Because of the fast proton transfer between molecular and protonated amines, only the sum of their concentrations can be determined. Furthermore, a byproduct was observed and quantified. The experimental data were used to develop a thermodynamic model of the studied electrolyte solutions, based on the extended Pitzer G E -model. In the model development, vapor-liquid equilibrium (VLE) data from the literature also were included. The model describes both the species distribution and the VLE of the studied mixtures. The properties of the quaternary system are predicted from information on the subsystems.

Solubility of Carbon Dioxide in Aqueous Solutions of N-Methyldiethanolamine in the Low Gas Loading Region

A headspace gas chromatography technique was applied to determine the solubility of carbon dioxide in aqueous solutions of 2,2‘-methyliminodiethanol (N-methyldiethanolamine, MDEA) at low gas loadings (at stoichiometric molar ratios of carbon dioxide to MDEA between about 0.003 and 0.8). A temperature range T ≈ 313−393 K was covered. The stoichiometric molality of MDEA in water amounted to about 2, 4, and 8 mol/(kg of water) (mass fraction of MDEA ≈ 0.192, 0.323, and 0.488). The partial pressure of carbon dioxide was between about 0.1 and 70 kPa. A thermodynamic model for describing the vapor−liquid equilibrium (which applies Pitzer's molality-scale-based equation for describing the Gibbs excess energy of the aqueous phase) is revised and extended using the new data.