Solutions Of N-methyldiethanolamine Research Articles

Селективная очистка природного газа с использованием промотированных растворов N­метилдиэтаноламина на Оренбургском ГПЗ

Селективная очистка природного газа с использованием промотированных растворов N­метилдиэтаноламина на Оренбургском ГПЗ

Kinetics of CO2 reaction with N-methyldiethanolamine and aminobutanol using stopped flow technique

Removal of carbon dioxide (CO2) from natural gas streams is mandatory to avoid pipeline corrosion, increase the heating value of the gas and reduce the gas volume in case of liquefied natural gas (LNG). The use of N-Methyldiethanolamine (MDEA) solution combined with other rate promoters such as Piperazine (PZ) is a common practice in Gas treatment technology. In this work, the use of Aminobutanol (AB) mixed with MDEA for the removal of (CO2) from natural gas streams is presented. The reaction kinetics of (CO2) with mixtures of MDEA and AB was investigated using stopped flow technique. The experiments were performed over a temperature range of 293 to 313 K and solution concentration of 0.5 and 1 moles/l in different MDEA/AB proportions. Obtained kinetics data were interpreted using zwitterion mechanisms for the primary amine AB. The individual rate constants of the participating reactions were regressed and their corresponding activation energies were estimated.

Enzyme-enhanced CO2 absorption process in rotating packed bed

Carbon dioxide is considered the most important contributor to the global warming effect. To reduce greenhouse gas emissions, CO2 should be separated from the exhaust gas stream in a selective way. The most often applied technology to capture CO2 from exhaust gases is the reactive absorption in aqueous amine solutions, which is currently widely used in different industrial applications. The efficiency of this technology could be improved by applying high-gravity technologies that intensify mass transfer and can enable substantial equipment size reduction compared to the traditionally used packed columns. Rotating packed bed (RPB) technology meets these requirements very well. Applying innovative materials such as the highly efficient enzyme carbonic anhydrase can further improve the efficiency of the CO2 absorption process. This combination of intensified technology together with new solvents is expected to improve the total efficiency of CO2 absorption. In this study, we present our experimental results of CO2 absorption using 30 wt% N-methyldiethanolamine (MDEA) solution in water in an RPB unit with and without carbonic anhydrase for different gas and liquid flow rates. The results indicate significantly improved performance of CO2 absorption, up to 18 times compared to the solvent without enzyme.

Experimental Study of Carbon Dioxide Solubility in Aqueous N-Methyldiethanolamine Solution with 1-Butylpyridinium Tetrafluoroborate Ionic Liquid

New experimental data for CO2 solubility in the aqueous solutions of N-methyldiethanolamine (MDEA) and 1-butylpyridinium tetrafluoroborate ([Bpy][BF4]) ionic liquid (IL) are reported. The experiments were conducted in a static high pressure equilibrium cell. Solubility measurement of CO2 was performed in various solution compositions of IL and MDEA in a wide temperature range of 298.15–343.15 K and pressures up to 4 MPa. The experimental results revealed that, by increasing the weight percent of IL, the absorption capacity of aqueous mixtures diminishes. It was also observed that the main capacity of CO2 loading in the absorbent solutions belonged to MDEA through chemical absorption, whereas its concentration was more effective than IL in gas solubility. The experimental results are correlated using a semiempirical model with good accuracy.

Enhancement of CO2 solubility in a mixture of 40 wt% aqueous N-Methyldiethanolamine solution and diethylenetriamine functionalized graphene oxide

Graphene oxide functionalized by diethylenetriamine (DETA) was prepared and characterized with SEM, XRD, BET, TGA and IR spectroscopy techniques to find out its morphology, crystalline building, porous structure, thermal stability and functional groups. The CO2 solubility in 40 wt% aqueous amine solution, 40 wt% aqueous amine solution +0.1 wt% GO, and 40 wt% aqueous amine solution +0.1 wt% DETA-GO is determined. The solubility measurements were performed at three temperature (303.15, 313.15 and 323.15 K) and CO2 partial pressures up to 2200 kPa. Addition of GO and DETA-GO to MDEA (N-Methyldiethanolamine) solution enhanced the CO2 adsorption capacity of the aqueous amine solution up to 7.5% and 12.5%, respectively. Increasing CO2 partial pressure and decreasing temperature enhanced the CO2 solubility.

Different Strategies for Accelerated CO2 Absorption in Packed Columns by Application of the Biocatalyst Carbonic Anhydrase

Within this work, the combination of an energetically favorable aqueous N-Methyldiethanolamine (MDEA) solution and the enzyme carbonic anhydrase is investigated in a packed column pilot plant. The use of aqueous MDEA solution for CO2 separation is already known from natural gas applications, for which an increased driving force due to the higher partial pressures of CO2 overcompensates reaction kinetic limitations. The objective of the addition of carbonic anhydrase is to countervail the loss of separation efficiency caused by the lower driving force in CO2 capture from power plant flue gases. Hence, carbonic anhydrase acts as a key to harness the energetic advantage of these solvent systems. However, application of the enzyme also poses restrictions on the process. Especially compliance with the enzyme stability limits is challenging for desorption, which is generally performed at high temperatures.In order to determine an optimal implementation of the enzyme into the process the current work presents different strategies how to apply CA as a biocatalyst in reactive absorption processes and shows how absorption efficiency is influenced. For introducing the enzyme to a packed column two approaches are investigated in this study. The simplest way of application is to dissolve the enzyme in the solvent. This allows the enzyme to work exactly where the reaction kinetic limitation can be found, in the liquid boundary layer. However, due to the temperature sensitivity of the enzyme an additional enzyme recovery step prior to the desorber might be necessary if desorption is to be performed at high temperatures. The immobilization of the enzyme inside the absorption column presents an alternative to prevent this additional separation, but may cause additional mass transfer limitations at the solid particles in which the enzyme is immobilized. The immobilization and the necessity of a suitable packing in which the enzyme particles can be filled, also makes this strategy more complicated but allows placing the enzyme at a location of most suitable process conditions in the column. But most importantly it completely avoids that the enzymes experience high temperature in the desorber. Systematic investigations of the influence of specific liquid load, liquid inlet temperature, MDEA-concentration and enzyme immobilization on absorption performance are conducted. Dissolved enzyme showed a nearly three times higher absorption performance than the immobilized enzyme under equivalent operating conditions, however the immobilized enzyme concentration used was effectively 50 times lower, meaning the result is actually quite promising for immobilized CA. From the investigated operating conditions, a liquid inlet temperature of 20°C, a MDEA concentration of 30wt.-% and a liquid flow rate of 24 m3 m-2 h-1 showed the best absorption performance with the dissolved enzyme. The measured absorption rate was 7.57 times higher than without enzyme added.

On the estimation of viscosities and densities of CO2-loaded MDEA, MDEA + AMP, MDEA + DIPA, MDEA + MEA, and MDEA + DEA aqueous solutions

As noteworthy properties of amine aqueous solutions, the densities and viscosities of aqueous N-Methyldiethanolamine (MDEA) solutions and mixtures of MDEA with 2-Amino-2-methyl-1-propanol (AMP), Diisopropanolamine (DIPA), Monoethanolamine (MEA), and Diethanolamine (DEA) were estimated under CO2 gas loading using Adaptive Neuro-Fuzzy Inference System (ANFIS), Multi-Layer Perceptron Artificial Neural Network (MLPANN), Support Vector Machine (SVM), and Least Square Support Vector Machine (LSSVM). The density and viscosity were estimated as a function of temperature, CO2 loading, pressure, and molecular weight of mixtures. In this regard, the actual data points were collected from the literature. Genetic Algorithm (GA) was employed to determine hyper variables of the LSSVM approach and Levenberg–Marquardt algorithm was employed to optimize bias and weight values of the ANN model. In addition, Particle Swarm Optimization algorithm (PSO) was used to determine membership parameters of the ANFIS approach and related parameters of the SVM were optimized using GA. The developed tools can be of massive value for chemical engineers and chemists to have a quick check of the densities and viscosities of the aforementioned amine solutions. Results obtained from the proposed models are in satisfactory agreement with actual data. According to statistical analyses, while the obtained values of Mean Squared Error (MSE) and R-squared (R2) for estimating densities of amine solutions are 0.000011 and 0.9938, 0.000013 and 0.9937, 0.000009 and 0.9953, 0.000001 and 0.9993 for the ANN, ANFIS, SVM, and LSSVM models respectively, these values obtained 0.079 and 0.994, 0.113 and 0.9911, 0.0634 and 0.9971, 0.0079 and 0.9996 for estimating the viscosities of amine-based solutions.

CO2 Absorption in Mixed Aqueous Solution of MDEA and Cholinium Glycinate

A new mixed solvent system that consists of cholinium glycinate ([Cho][Gly]) and aqueous N-methyldiethanolamine (MDEA) solution was developed in this work to serve as CO2 absorbent. The equilibrium absorption was carried out to investigate the effect of solution composition, pressure, and temperature on CO2 absorption performance. The effect of CO2 absorption on the viscosity of the aqueous solutions was studied, and the regeneration efficiency of the aqueous solutions was also investigated. The results showed that the CO2 absorption loading decreased with increasing [Cho][Gly] concentration and temperature, and the absorption loading strongly depended on CO2 partial pressure. The reactivity of MDEA was significantly enhanced with the addition of [Cho][Gly]. The aqueous solution with (10 wt % [Cho][Gly] + 20 wt % MDEA) showed an optimal CO2 absorption and high regeneration efficiency. Furthermore, the CO2 absorption mechanism in the aqueous [Cho][Gly]-MDEA solution was explored by 13C nuclear magnetic res...

Multivariate Analysis in Selective Nitroacetophenone Conversion by Hydrogen Sulfide under Phase Transfer Catalysis

Response surface methodology (RSM) was employed to model and optimize an improved Zinin reduction of a nitroarene, p-nitroacetophenone (p-NAP), by hydrogen sulfide (H2S) under biliquid phase transfer catalysis. A novel Zinin reagent, H2S laden aqueous N-methyldiethanolamine (MDEA) solution, was prepared and used for this purpose. A quadratic regression model was tested with a multivariate experimental design based on the relationship between p-NAP conversion (response) and four independent variables—temperature, catalyst concentration, p-NAP–sulfide mole ratio, and MDEA concentration. The optimum values of the independent variables were found as temperature 339.45 K, catalyst concentration of 0.082 kmol/m3, p-NAP/sulfide mole ratio of 0.452, MDEA concentration of 2.20 kmol/m3, and maximum p-NAP conversion of 96.31% has been attained. The analysis of variance (ANOVA) has been used to evaluate the goodness of the fit of the model, and the desirability function has been used to find the value of the optimize...

Thermophysical properties of concentrated aqueous solution of N -methyldiethanolamine (MDEA), piperazine (PZ), and ionic liquids hybrid solvent for CO 2 capture

In the present study, thermophysical properties such as density, refractive index, surface tension, and viscosity of the concentrated aqueous solution of N-methyldiethanolamine (MDEA), piperazine (PZ), and ionic liquids (ILs) 1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][OTf], 1-butyl-3-methylimidazolium acetate [bmim][AC] were investigated. All the properties were measured at atmospheric pressure and temperature ranging from (298.15–343.15) K, with a regular interval of 5 K. The concentrations of N-methyldiethanolamine (MDEA) and piperazine (PZ) were kept constant at 30 and 3 wt%, respectively, while the concentration of ionic liquids [bmim][OTf], [bmim][AC] were varied between 5 and 20 wt%. All the properties under investigation demonstrated their significant dependence on temperature and ionic liquid concentration. Increasing temperature showed decreasing trend of density, viscosity, refractive index, and surface tension of the hybrid solvents. Except for surface tension, density, refractive index, and viscosity were increased by increasing the concentration of ionic liquid in the hybrid solvents. Surface tension data were decreased with an increase in the concentration of ionic liquids at a constant temperature. The thermophysical properties of concentrated aqueous solution of hybrid solvents were correlated using an empirical correlations approach with respect to temperature and concentration. A good agreement was found between the correlated and experimental data at all conditions.

Modeling of CO2 solubility in aqueous N-methyldiethanolamine solution using electrolyte modified HKM plus association equation of state

In this work, a new type of electrolyte cubic plus association equation of state as emHKM-CPA EoS has been developed and was used to modeling the CO2 solubility in aqueous alkanolamine such as N-methyldiethanolamine (MDEA) and diethanolamine (DEA) solutions. This EoS consists of the several terms as the cubic HKM part for dispersion contribution, electrolyte part and association term. The Mean Spherical Approximation (MSA) term together with Born term are used for electrostatic long-range interaction and charging processes, respectively, and for association the Wertheim equation was applied. Using the present EoS, the solubility of CO2 in aqueous MDEA solutions is modeled so that the 470 experimental solubility data were used at the different solution compositions, temperatures, pressures and acid gas loadings. At first, the pure components parameters were obtained through regression of the pure components vapor pressure and saturated liquid density experimental data. Consequently, the binary interaction parameters were calculated using the binary vapor-liquid equilibrium data. Finally, the ternary H2O-CO2-MDEA and H2O-CO2-DEA systems were modeled using a reactive bubble point pressure calculation method. Moreover, the present EoS is applied for LLE calculation of heptane-MEA system. The results showed that the calculated values were in good agreement with the experimental data. For the H2O-CO2-MDEA and H2O-CO2-DEA systems, the percentage of Absolute Average Deviation (AAD%) were 12.14 and 9.17, respectively, that shows emHKM- CPA is an efficient EoS which can be successfully applied to representation of the solubility of CO2 in aqueous alkanolamine solutions in wide ranges of temperature, pressure, acid gas loading, and amine concentration.

A new CO2 absorption data for aqueous solutions of N-methyldiethanolamine + Hexylamine

The aim of this work is to develop a new chemical solvent for CO2capture and compare its performance with a reference based solvent MDEA (MethylDiEthanolAmine). A mixture of MDEA and Hexylamine activator (HA) is designed to improve the performance of the process and allow a substantial gain in terms of energy regeneration and reducing the cost of capture. New CO2 absorption data is obtained using a Lewis cell gas-liquid interface at 298, 313 and 333 K with mass concentrations MDEA 37 wt%+ HA 3 wt%,MDEA 35 wt%+ HA 5 wt% and MDEA 33 wt%+ HA 7 wt%, to assess the CO2 absorption flux and the absorption capacity of the new solvent. Our results show that for the mixture of MDEA 37 wt%+ HA 3 wt%, the kinetics reaction is fast with reduced activation energy compared to that of MDEA 40 wt%.

Evaluation of density, viscosity, surface tension and CO2 solubility for single, binary and ternary aqueous solutions of MDEA, PZ and 12 common ILs by using artificial neural network (ANN) technique

In this study, density, viscosity, surface tension and CO2 solubility for single, binary and ternary aqueous solutions of N-methyldiethanolamine (MDEA), piperazine (PZ) and 12 common ionic liquids (ILs) were predicted by applying artificial neural network (ANN) technique. The input data included operating temperature (293.15–373.15K) and pressure (0.177–3938.400kPa) in addition to the weight fractions of aqueous solutions of MDEA, PZ and ILs which were respectively in the range of (0.0–1.0), (0.0–0.09) and (0.0–1.0) as well as the molecular weight of ILs (148.18–505.00g/mol) and their acentric factors (0.325–1.261). More than 2600 experimental data points for density, viscosity, surface tension and CO2 solubility were collected from literature. By using the Levenberg-Marquardt back-propagation and tan-sigmoid as learning algorithm and transfer function, respectively, four ANN models were examined to treat these data. It was found that the best ANN architectures for predicting these properties were respectively (7:3:0:1), (7:6:0:1), (7:4:0:1) and (7:10:0:1). The calculated properties were compared with the corresponding experimental data which indicated a negligible error.

Remarkable enhancement of convective heat transfer with different nanoparticles in N-methyldiethanolamine solution in gas sweetening process

In this work, effective thermal conductivity and convective heat transfer at different Reynolds number of nanofluid containing nanometer-size particles in N-methyldiethanolamine solution is measured. Thermal conductivity and stability of nanostructures in water-based nanofluid, as well as their dependence to temperature and time variation, are of a great concern. These nanofluids consists of 0.1 mass fraction of spherical silica nanoparticles (SiO2), carbon nanofiber (CNF), UiO-66-NH2 MOF, carbon nanotube functionalized with carboxylic acid as ligand (CNT-COOH), MgO nanoparticles, and colloidal silica. These nanofluids mixed with of N-methyldiethanolamine solution and thermal conductivity coefficients were measured. The appropriate result demonstrated the thermal conductivity is highly related to the optimum concentration of nanoparticle in base fluid, velocity, flow rate, and heat flux. It was found that a combination of CNF and SiO2 nanoparticles in a 1:1 ratio with 0.1wt.% could enhanced thermal conductivity which will induces greater enhancement by combined nanoparticle base amine fluid in heat transfer application. It has been shown increase of Reynolds number at the mass concentration 0.1wt.% an increase in convective heat transfer coefficient of nanofluid about 13%. These results improve the thermal conductivity properties of solution in amine plants.

Measuring solubility of hydrogen sulphide in aqueous blends of N-methyldiethanolamine and 2-((2 aminoethyl)amino)ethanol and correlating by the Deshmukh–Mather model

The solubility of hydrogen sulphide (H2S) in aqueous solution of N-methyldiethanolamine (MDEA) in the presence of different mole ratios of 2-((2-aminoethyl)amino)ethanol (AEEA) at low and medium pressures was obtained. The total concentrations of all the solutions have been fixed equal 3.36mol·L−1 (5.37 total moles of amines·kg−1 water). The mole ratio of [AEEA]/[MDEA] (mole ratio of AEEA per MDEA in fresh solutions) was set to 0.05, 0.10 and 0.125. The experimental total pressure varied from (7.3 to 1500) kPa and the temperatures were set to (313.2, 328.2, 343.2 and 358.2)K. The experimental values are presented as the total pressure against acid gas loading (mole H2S/total moles of amine). The results show that the AEEA concentration can improve absorption capacity of MDEA aqueous solution as the mole ratio [AEEA]/[MDEA] increases at constant total concentration. The Deshmukh–Mather model and Peng–Robinson equation of state were used for liquid and vapour phases, respectively to correlate the solubility of H2S in aqueous mixtures of AEEA and MDEA. The overall average absolute percent deviation (AAD%) in calculating the total pressure as a function of H2S loading obtained 8.15% for (AEEA–MDEA–H2S–H2O) quaternary system at the entire temperature and pressure ranges in this work.

Influence of temperature on the kinetics of enzyme catalysed absorption of carbon dioxide in aqueous MDEA solutions

In the present work the absorption of carbon dioxide in 1000molm−3 N-methyldiethanolamine (MDEA) solutions with and without enzyme has been studied in a stirred cell reactor in the temperature range 278–343K and enzyme concentrations ranging from 0 to 1600gm−3. During this study a new type of carbonic anhydrase has been tested: the evolved tetrameric enzyme GS6-046. The kinetic data from the new enzyme has been compared to the kinetic data obtained with the thermostable CA mutant 5X and the new enzyme showed a faster kinetics towards the CO2 hydration in combination with MDEA.The experimental kinetic data from the evolved CA at the temperatures 278, 288 and 313K resulted in a temperature dependent equation for the enzymatic rate constant kH2O*. In the temperature range 278–313K, this equation predicts kH2O* within an accuracy of 30%. However, at 343K the measured kH2O* is significantly overestimated.

A Fugacity Corrected Thermodynamic Framework for Aqueous Alkanolamine Solutions

A generalized thermodynamic framework for correlating the vapor–liquid equilibria of aqueous primary, secondary and tertiary alkanolamine solutions is presented. The model uses Universal Functional Activity Coefficient (UNIFAC) and translated modified Peng–Robinson equation of state to correlate the activity and fugacity effects of the solution, respectively. New UNIFAC binary interaction parameters are reported for aqueous monoethanolamine, diethanolamine and N-methyldiethanolamine solutions for a wide range of temperature, pressure and concentration. The results are in excellent agreement with experimental data.

Studies on the effect of addition of piperazine and sulfolane into aqueous solution of N-methyldiethanolamine for CO2 capture and VLE modelling using eNRTL equation

In this work, new experimental vapour liquid equilibrium (VLE) data and modelling work of VLE of CO2 in piperazine (PZ) activated aqueous solutions of n-methyldiethylamine (MDEA) are presented. Besides, experimental VLE data of CO2 in a hybrid solvent, containing sulfolane as physical solvent along with aqueous (MDEA+PZ), have also been reported over the temperature range of 308–328K and CO2 partial pressure range of 1–1400kPa. The concentrations of MDEA in the aqueous solutions are 22–28mass% and also 42–48mass%. PZ is used as a rate activator within a concentration range of 2–8mass%. The total amine concentration in the aqueous solutions of (MDEA+PZ) has been kept within 30mass% and also 50mass%, while for the hybrid solvent the concentration of sulfolane has been maintained at 10mass% along with total 50mass% (MDEA+PZ). Electrolyte non random-two liquid (eNRTL) theory has been used to model the VLE. It has been found that there is a good agreement between the experimental and model results of CO2 solubility in PZ activated MDEA solutions. The CO2 cycle capacity is calculated considering a set of lower and higher CO2 partial pressures corresponding to lower (lean solvent) and higher (rich solvent) equilibrium CO2 loadings. For the sulfolane based hybrid solvent, it has been observed that the CO2 cyclic capacity of the solvent decreases with the lower lean-rich partial pressure range of 10–100kPa, but increases at higher partial pressure ranges of 100–1000kPa at 323K. PZ mass% in the hybrid solvent has also been found to have a positive effect on the CO2 cyclic capacity.

CO2 solubility in aqueous solutions of N-methyldiethanolamine+piperazine by electrolyte NRTL model

Accurate modeling of the solubility behavior of CO2 in the aqueous alkanolamine solutions is important to design and optimization of equipment and process. In this work, the thermodynamics of CO2 in aqueous solution of N-methyldiethanolamine (MDEA) and piperazine (PZ) is studied by the electrolyte non-random two liquids (NRTL) model. The chemical equilibrium constants are calculated from the free Gibbs energy of formation, and the Henry’s constants of CO2 in MDEA and PZ are regressed to revise the value in the pure water. New experimental data from literatures are added to the regression process. Therefore, this model should provide a comprehensive thermodynamic representation for the quaternary system with broader ranges and more accurate predictions than previous work. Model results are compared to the experimental vapor-liquid equilibrium (VLE), speciation and heat of absorption data, which show that the model can predict the experimental data with reasonable accuracy.

CFD Modelling of a Hollow Fibre Membrane for CO2 Removal by Aqueous Amine Solutions of MEA, DEA and MDEA

Abstract A mass transfer model was developed to capture CO2 from a gas mixture in hollow fibre membrane contactors under laminar flow conditions. The axial and radial diffusions through membrane and convection in tube and shell sides with chemical reaction were investigated. COMSOL software was used to numerically solve a system of non-linear equations with boundary conditions by use of the finite element method. Three different amine solutions of monoethanolamine (MEA), diethanolamine (DEA) and n-methyldiethanolamine (MDEA) were chosen as absorbent in lumen to consider the mass transfer rate of CO2 and its removal efficiency. The modelling results were compared with experimental data available in the literature and a good agreement was observed. The CFD results revealed that MEA had the best performance for CO2 removal as compared to DEA and MDEA under various operating conditions due to the different CO2 loading factor of absorbents. Furthermore, efficiency of CO2 removal was highly dependent on the absorbent concentration and flow rate, increasing of the gas flow rate caused a reduction in gas residence time in the shell and consequently declined CO2 mass transfer. The modelling results showed the effect of absorbent concentration on the CO2 mass transfer was improved due to availability of absorbent reactants at the gas-liquid interface.