Solubility Of N2O Research Articles

The N2O analogy in the CO2 capture context: Literature review and thermodynamic modelling considerations

The literature review presented in this work shows that, despite the central role of the N2O analogy, there is no sound evidence in literature that the ratios of the solubility of N2O to that of CO2 in water can be used for correlating the solubilities of the two gases in the systems of industrial interest for post combustion CO2 capture, for instance 5M MEA. On the contrary, the data evaluated in this work indicates that the use of the ratio of the solubility of N2O to that of CO2 in water may be restricted to systems that are much more dilute than that. The use of the ratio requires that good correlations for Henry’s constants of CO2 and N2O in water are available. However, we show there is a remarkable lack of VLE data on the N2O–water system in literature.A thermodynamic modelling of Henry’s constants of CO2 and N2O in water is conducted, and two alternative correlations are provided: one for operations up to 1MPa (typical of post-combustion CO2 capture), and the other for operations up to 20MPa (for natural gas sweeting process). The correlations for the ratio of the solubility of N2O to that of CO2 in water are presented together with their 95% confidence bands.

Density and N2O solubility of aqueous hydroxide and carbonate solutions in the temperature range from 25 to 80 °C

The solubility of N2O in aqueous solutions of hydroxides containing Li+, Na+ and K+ counter ions and the hydroxide blends with carbonates were measured for a range of temperatures (25–80°C) and concentrations (0.08–3M). To evaluate the solubility experiments in terms of apparent Henry׳s law constant [kPam3kmol−1], the accurate liquid densities of these systems were measured by an Anton Paar Stabinger Density meter DMA 4500. The measured densities were compared with Laliberté and Cooper׳s density model (Laliberte and Cooper, 2004) with less than 0.3% AARD (Average Absolute Relative Deviation). By using the experimental data for N2O solubility, the parameters in the model of Weisenberger and Schumpe (Weisenberger and Schumpe, 1996) were refitted for aforementioned systems. The ion specific and temperature dependent parameters for these systems in the original model, valid up to 40°C and 2M concentration, were refitted to extend the validity range of the model up to 3M and 80°C with 4.3% AARD.

Reactive Absorption of Carbon Dioxide in l-Prolinate Salt Solutions

Aqueous amino acid salt solutions are seen as more sustainable alternative CO2 solvents compared to conventional alkanolamines. The absorption of CO2 into aqueous solutions of potassium l-prolinate, over the temperature range of 290–303 K, was studied using a stirred cell. To compare the effect of potassium versus sodium as counterion, the absorption rates of CO2 in sodium l-prolinate solutions were also determined. The amino acid salt concentration was varied between 0.5 and 3 mol dm–3. Physicochemical properties such as density, viscosity, and physical solubility of N2O, required in the interpretation of absorption rate experiments, were determined separately. The obtained experimental reactive absorption fluxes were interpreted, using the pseudo-first-order approach, into intrinsic reaction kinetics. The potassium-based solvent showed, on average, a 32% higher reactivity toward CO2 than the sodium equivalent. The kinetic data were correlated in a power-law reaction rate expression. The reaction order with respect to the amino acid was found to be between 1.40 and 1.44 for both l-prolinate salts, and the second order kinetic rate constant, k2, was calculated for the potassium salt to be 93.7 × 103 dm3·mol–1·s–1 at 298 K with an activation energy of 43.3 kJ·mol–1. l-Prolinate salts show higher chemical reactivity toward CO2 than most of the amino-alcohols and amino acid salts.

Physical Properties of Partially CO2 Loaded Aqueous Monoethanolamine (MEA)

Monoethanolamine (MEA) is commonly used as a benchmark for solvent development within postcombustion CO2 capture. The physical properties data for this system are scarce, especially for loaded solutions. In this paper new measurements of physical properties (density, viscosity, and physical N2O solubility) of unloaded and loaded solutions are presented. Available literature data were collected, and semiempirical models were developed and shown to represent all experimental data very well.

Determining the Diffusivity of Nitrous Oxide in Soil using In Situ Tracers

Diffusion is a key process for understanding the movement of nitrous oxide (N2O), carbon dioxide (CO2), methane (CH4), oxygen (O2), and other biogeochemically important gases in soil. Soil gas diffusivity is highly variable, which makes the application of generic predictive models based on soil macrofeatures uncertain. In situ methods provide greater certainty but intensive sampling usually makes such determinations expensive. We compared single and inter-port diffusivity determinations using a sparse sampling alternative. We used 28 in situ profile probes with ports at five depths for pulse sulfur hexafluoride (SF6) and N2O tracer injections at single ports followed by two or three measurements in five adjacent ports at an agricultural site in southwest Michigan, USA. We repeated this procedure for three dates in the summer and two in the fall. In general, the sparse method provided accurate measurements of soil diffusivity. Estimated diffusivities of SF6 and N2O had poorer agreement in the summer (r2 = 0.49) than in the fall (r2 = 0.96), likely due to less uniform soil moisture in summer. The low N2O to SF6 diffusivity ratio (0.67 compared with 1.82 in free air) suggests that water solubility of N2O plays a significant role in retarding its movement in the soil. Movement of the relatively insoluble SF6 is not obscured by dissolution in water making SF6 a superior tracer compared with N2O. Median diffusivities in ports where the gas was injected were only moderately correlated (r2 = 0.45) with diffusivities at the same depth measured by the inter-port method, likely due to an increase in the variability of diffusivity with distance from the injection port. Results show it is possible to estimate N2O diffusivity with sparse measurements; accuracy can likely be further improved with knowledge of soil moisture and texture in the immediate vicinity of the injection and sampling ports, as uncertainty in water modeling is reduced.

Isotopomer analysis of production, consumption and soil-to-atmosphere emission processes of N2O at the beginning of paddy field irrigation

In irrigated rice paddies, episodic release of nitrous oxide (N2O) from the soil to the atmosphere has been observed during the first flood irrigation, but the biogeochemical mechanisms underlying these emissions remain unclear. To elucidate both microbial pathways of N2O production, consumption and emission processes of N2O from soil surfaces, we analyzed isotopomer ratios (bulk nitrogen and oxygen isotope ratios, δ15Nbulk and δ18O, and intramolecular 15N site preference, SP) of surface-emitted N2O and N2O in soil gas from paddy fields in Japan at the beginning of irrigation. Results indicate that surface-emitted N2O is produced at shallow depths above the rising groundwater table, and that it is emitted by diffusive transport through air-filled soil pores. Immediately after soil surfaces are submerged, N2O accumulates in the soil because of the low diffusivity and high solubility of N2O in water. Isotopomer analysis revealed that high N2O emissions during the flooding process resulted mainly from N2O production by bacterial denitrification (nitrate reduction). Moreover, as soil submergence progressed, declining soil NO3− concentration promoted the use of N2O as an electron acceptor. Thereby, most of the N2O was reduced to N2. N2O emissions were increased by nitrogen fertilizer application before irrigation. The applied nitrogen fertilizer might enhance N2O production.

Density of PG+AMP+H<sub>2</sub>O and Solubility of N<sub>2</sub>O in PG+AMP+H<sub>2</sub>O

Density of PG+AMP+H<sub>2</sub>O and Solubility of N<sub>2</sub>O in PG+AMP+H<sub>2</sub>O

Prediction of N2O Solubility in Alkanolamine Solutions from the Excess Volume Property

The CO2 solubility is very important property when establishing thermodynamic models for the VLE. In order to obtain the CO2 solubility the normal procedure is to use the N2O analogy as the CO2 solubility cannot be directly measured. This calls for a rather extensive experimental program. In this work a simple and less laborious model was developed based on the excess molar volumes to estimate the excess Henry's constant. This method only requires density data and the N2O solubility into pure solvents (Water/Alkanolamine). The model works well to represent experimental data for different temperatures and concentrations.

Solubility of N2O in and Density and Viscosity of Aqueous Solutions of Piperazine, Ammonia, and Their Mixtures from (283.15 to 323.15) K

Solubilities of N2O in and densities and viscosities of aqueous solutions of ammonia, piperazine (PZ), and their aqueous blends were measured at (283.15, 293.15, 303.15, 313.15, and 323.15) K. The experiments cover the mass fraction ranges: (1 to 30) mol % ammonia, (0.1 to 2) mol % PZ, and (1 to 11) mol % ammonia + (0.18 to 2) mol % PZ in the blended solutions. The results are compared with available data in the literature. The experimental density and viscosity data were correlated using two semiempirical correlations as a function of temperature and concentration of ammonia and PZ.

Solubility and Diffusivity of N2O in Aqueous 4-(Diethylamino)-2-butanol Solutions for Use in Postcombustion CO2 Capture

In this work, the solubility and diffusivity of nitrous oxide (N2O) in aqueous 4-(diethylamino)-2-butanol (DEAB) solutions were measured. Solubility was measured in a stirred cell reactor over the temperature range of 298–343 K and concentration range of 0.68–3.77 M. On the other hand, diffusivity was measured in a laminar jet absorber over the temperature range of 298–318 K and concentration range of 1.0–2.5 M. An attempt was made to correlate the solubility data with well-known models (semiempirical model, Redlich–Kister equation, and polynomial model). It was observed that only the polynomial model correlated the solubility of N2O in aqueous DEAB solution satisfactorily with an AAD of 0.1%. Similarly, an attempt was made to correlate the diffusivity data with well-known models (semiempirical model and modified Stokes–Einstein model). The semiempirical model provided better predicted N2O diffusivity data compared with the experimental data with an AAD of 3.4%. These data can then be used to determine th...

Density, viscosity, physical solubility and diffusivity of CO2 in aqueous MDEA + [bmim][BF4] solutions from 303 to 333 K

In this study, the physical solubility and diffusivity of N2O in aqueous MDEA+[bmim][BF4] solutions were measured over a range of temperatures of 303–333K and [bmim][BF4] concentrations of 0–2.0molL−1 at atmospheric pressure. The total MDEA concentration in the solutions was kept constant at 4molL−1. The “N2O analogy” was then used to estimate the physical solubility and diffusivity of CO2 in aqueous MDEA+[bmim][BF4] solutions. The density and viscosity of aqueous MDEA+[bmim][BF4] solutions were also measured over the same range of temperatures and concentrations of the ionic liquid. These data were used to develop correlations for the prediction of CO2 diffusivity in these systems.

The physical solubilities and diffusivities of N2O and CO2 in aqueous ammonia solutions on the additions of AMP, glycerol and ethylene glycol

Carbon dioxide (CO2) is a major greenhouse gas, the emissions of which should be reduced. There are various technologies for the effective separation of CO2. Of these, chemical absorption methods are generally accepted as the most effective. The monoethanolamine (MEA) process is an effective way to remove CO2, but is an expensive option for the separation of CO2 from massive gas-discharging plants. Therefore, ammonia solution, which is less expensive and more effective than MEA, was used for the removal of CO2. In this study, the physical solubility of N2O in (ammonia+water), (ammonia+2-amino-2-methyl-1-propanol+water), (ammonia+glycerol+water) and (ammonia+ ethylene glycol+water) was measured at 293, 303, 313, 323 K. Additive concentrations of 1, 3, and 5 wt% AMP, glycerol and ethylene glycol were added for each 9 wt% ammonia solution. A solubility apparatus was used to investigate the solubility of N2O in ammonia solutions. The diffusivity was measured with a wetted wall column absorber. The “N2O analogy” is used to estimate the solubility and diffusivity of CO2 in the aqueous ammonia solutions. OriginPro 7.5 was used to correlate the solubility and diffusivity of N2O in ammonia solutions. The parameters of the correlation were determined from the measured solubility and diffusivity.

CO2Absorption into Mixed Aqueous Solutions of 2-Amino-2-hydroxymethyl-1,3-propanediol and Piperazine

Solubility data of CO2 in aqueous mixtures of 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD) and piperazine (Pz) were measured over a range of temperature from 288.15 to 333.15 K and for total amine concentrations up to 3.1 kmol·m−3. The CO2 partial pressure was kept within 0.21−2 637 kPa using a vapor−liquid equilibrium (VLE) apparatus based on a static-analytic method. The solubility of N2O in the Pz−AHPD aqueous solutions was also performed in order to determine, with the N2O analogy, the Henry’s law constant of CO2 in these solutions. The experimental data for the ternary system AHPD−CO2−H2O were correlated using a modified Pitzer’s thermodynamic model for the activity coefficients combined with the virial equation of state for representing the fugacity coefficients. The solubility of carbon dioxide in aqueous solutions of mixed amine (Pz + AHPD) was predicted by supposing that the parameters characterizing the single amine systems are essential for describing the quaternary system behavior.

Solubility of N2O in aqueous monoethanolamine and 2-(2-Aminoethyl-amino)ethanol solutions from 298 to 343 K

The solubility of N2O in MEA and AEEA were measured at concentrations of 30 wt% and pure solutions for the temperatures between 298 and 343 K. The solubility of N2O decreases as the amine molecular weight increases in 30 wt% solutions. In pure amine solutions the trend is opposite. Solubilities of CO2 and N2O in water were also measured in the same range of temperatures. The ratio between the solubility of CO2 and that of N2O in water is dependent on temperature but an average value of 0.72 can be used.

Kinetics of carbonate based CO2 capture systems

Abstract The Henry’s law constants for physical solubility of N2O were measured up to 80 ∘C for sodium and potassium carbonate solutions and the results were compared with the model of Weisenberger and Schumpe (1996). Overall gas phase mass transfer coefficients were measured with a string of discs apparatus for 5–30 wt-% sodium carbonate solution and for 5–50 wt-% potassium carbonate solution up to 70 ∘C. The Henry’s law constants measured in this study agree well with literature. The Henry’s law constants increase with temperature and carbonate concentration. The model of Weisenberger and Schumpe agrees well with measured data at 25 ∘C, but it underestimates the Henry’s law constant at higher temperatures. Overall mass transfer coefficients for potassium and sodium carbonate increase with temperature but decreases with concentration at high concentrations. Potassium carbonate solutions have higher overall mass transfer coefficients than sodium carbonate. Adding amines as promoter gives decade higher absorption rates compared to pure carbonate solutions.

Solubility of N2O in Aqueous Solution of Diethylenetriamine

The solubilities of N2O in aqueous diethylenetriamine (DETA) solution at different mass fractions (15, 30, 45, 60, 75, 90, and 100) % of DETA were measured at different temperatures of (297.7 to 360.7) K. The solubility of N2O in aqueous DETA solution is strongly dependent on both temperature and mass fraction of DETA. A semiempirical model considering the excess quantity of Henry’s constant was correlated with the Redlich−Kister equation. The model gave satisfactory agreement with the experimental data.

Physiochemical Properties of Several Aqueous Potassium Amino Acid Salts

Aqueous amino acid salt solutions might be an attractive alternative over traditional alkanolamines in the removal of CO2 from flue gases especially because of their oxidative stability and negligible volatility. The density and viscosity of the aqueous solutions of the potassium salts of the following amino acids have been measured: β-alanine, 6-aminohexanoic acid, l-arginine, l-aspartic acid, l-glutamic Acid, dl-methionine, l-phenylalanine, l-proline, and sarcosine. Data are reported in the temperature range of (25 to 60) °C and concentration range of (0.25 to 3.5) mol·L−1. The data could be correlated accurately with relatively simple relations. The physical solubility of N2O in the same amino acid salt solutions was also measured at a temperature of 298 K and a concentration of 0.5 mol·L−1 of the amino acid salt. Using the N2O/CO2 analogy on one hand and Schumpe’s method on the other, the physical solubility of CO2 in these solutions was estimated. Both methods yielded results very close to each other.

Physical Solubility and Diffusivity of N2O and CO2 in Aqueous Solutions of Piperazine and (N-Methyldiethanolamine + Piperazine)

In this work, the physical solubility and diffusivity of N2O in aqueous solutions of piperazine (PZ) and an aqueous blend of N-methyldiethanolamine (MDEA) and piperazine have been measured over a range of temperatures and at atmospheric pressure. For the binary mixtures, the mass percents of PZ used are (1.74 to 12) %. For the ternary mixtures, the total amine strength in the solution has been kept at 30 mass %. The “N2O analogy” is then used to estimate the physical solubility and diffusivity of CO2 in aqueous PZ and PZ-blended aqueous MDEA solutions. The experimental physical solubility and diffusivity data have been correlated as a function of temperature and concentration of amine and compared with the available data in the literature.

Kinetics of CO2 Absorption in Aqueous Sodium Glycinate Solutions

The physical solubility and diffusivity of N2O and CO2 in aqueous sodium glycinate (SG) solutions of various concentrations (1.0−3.5 kmol/m3) and temperatures (303.15−323.15 K) were reported. The kinetics of the reaction between CO2 and SG has been studied using absorption data measured by a wetted-wall column apparatus at various temperatures and concentrations. The second-order rate constant of CO2 with SG was determined to be k2(m3 kmol-1 s-1) = 1.95 × 1013 exp(−7670/T), where T is the absolute temperature (given in Kelvin). The activation energy for the reaction of CO2 with SG was calculated to be 63.8 kJ/mol.

Physical Solubility and Diffusivity of N2O and CO2 in Aqueous Sodium Glycinate Solutions

Physical solubility and diffusivity of N2O and CO2 in pure water and of N2O in aqueous sodium glycinate solutions of mass fraction (0.1 to 0.5) were measured at T = (303.15 to 323.15) K. Since it was not possible to measure these properties for CO2 due to the chemical reaction between CO2 and the amine group of sodium glycinate, these were estimated using the well-known N2O analogy. While the physical solubility increases with a decrease in temperature and with a decrease in mass fraction, diffusivity decreases with a decrease in temperature as well as an increase in mass fraction except for concentrated solution (mass fraction 0.4 and 0.5) where it increases with a decrease in temperature.