Acid Gas Loading Research Articles

Predicted Separation of Acid Gases from Gas Mixtures by Functionalized Porous Aromatic Frameworks.

The selective adsorption of target acid gas molecules from binary gas mixtures by porous aromatic frameworks (PAFs) with two identical functional groups per aromatic ring (PAF-R2) was computationally investigated using grand canonical Monte Carlo simulations. PAF-R2 adsorption was considered for three binary mixtures of small molecular concentrations of acid gas and abundant nitrogen gas (CO2/N2, SO2/N2, and H2S/N2). The results indicate that additional functional groups enhance acid gas loadings and selectivity, compared with pristine PAF and single-functionalized PAFs. Low pressures yield linearly increasing gas loadings and constant selectivity, while high pressures yield much higher adsorption and selectivity. In particular, SO2 loading and selectivity under high pressures are heavily influenced by the PAF's maximum adsorption limit, which can be linked back to the functional groups and their configuration. In summary, PAF-(3,5)-(COOH)2 (nomenclature of PAFs is provided in the Appendix in the Supporting Information) and many other PAF with the same two electron-withdrawing groups are predicted to have great acid gas adsorption and selectivity from gas mixtures, while PAF-(3,5)-(OH)2 (one of PAFs with two identical electron-donating groups) is predicted to have good adsorption and selectivity, especially under elevated pressures. The results of this work can provide insights into various types of PAFs with great selective adsorption ability and their corresponding conditions. The simulation procedures and results may inspire the exploration and screening of other types of PAFs or porous materials, for acid gas absorption.

High-pressure solubility measurement and eNRTL thermodynamics modeling of carbon dioxide in aqueous solutions of 2-((2-aminoethyl) amino) ethanol + dimethyl sulfoxide at different conditions

We measured the solubility of carbon dioxide in the aqueous solution of 2-((2-aminoethyl) amino) ethanol (AEEA) as a chemical solvent plus dimethyl sulfoxide (DMSO) as a physical solvent. A quasi-static high-pressure equilibrium cell was used for the measurement of CO2 solubility in the AEEA + DMSO + H2O systems at the compositions of (10, 20, 70), (15, 15, 70), (20, 10, 70), (25, 5, 70) wt. %. We performed the experiments at temperatures of 318.15, 328.15, and 343.15 K and pressures up to 5000 kPa. Also, we compared the CO2 solubility in the aqueous mixture of 2-((2-aminoethyl) amino) ethanol (AEEA) + dimethyl sulfoxide (DMSO), 2-((2-aminoethyl) amino) ethanol (AEEA) + sulfolane, methyl diethanolamine (MDEA) + dimethyl sulfoxide (DMSO), and methyl diethanolamine (MDEA) + sulfolane. We used the Electrolyte-NRTL thermodynamic model to correlate the solubility of CO2 in the aqueous solutions of AEEA + DMSO and to predict the partial pressure of CO2 versus the acid gas loading. The present modeling provided an excellent representation of the experimental data over the whole temperature range for 121 experimental data, which resulted in an average absolute deviation of 12.96 %.

Robust synthesis of amine-based natural gas sweetening plants

The natural gas processing and refining industry uses acid gas removal units to improve the quality of their sour gas feed to a certain level. Various disturbances such as sour gas feed conditions or solvent quality can influence the operation of such plants. A framework is developed using linear control tools which can be used to assess the flexibility of the operating condition of a sweetening plant against such disturbances. A quantitative measure of the flexibility and controllability of a design is provided as a systematic tool for the designer to evaluate different process structures or conditions. The framework can also be used to calculate the maximum tolerable disturbances by the process. The framework is illustrated in a plant that removes acid gas from a raw gas stream using MDEA as the solvent. The parameter σ1 as the maximum singular value of the steady state transfer matrix of the plant is considered as the sensitivity of the outlet H2S and CO2 purities against external disturbances where a higher value means more sensitivity. The results show that higher solvent concentrations are preferred considering the robustness of the absorption column against the sour gas feed disturbances and the uncertainties of the solvent properties. For example, at the solvent flow rate of 40,000 kg/h, the value of σ1 is 2.817, 0.736 and 0.148 at the wt% of 20%, 30% and 40%, respectively. Also, it is shown that for a plant designed with the sweet gas H2S purity of 2 ppm, when a solvent with 20 wt% and flow of 88897.3 kg/h is used, the feed quality disturbance of 0.59 kg/h and 505.19 kg/h in the H2S and CO2 mass flows relative to their nominal can be tolerated before reaching the maximum allowable value of 3 ppm. Such calculations at the 45% point with solvent flow of 44015.8 kg/h lead to the maximum tolerable disturbance of 1.79 kg/h and 967.36 kg/h in the H2S and CO2 flows. The rationale behind this behavior can be well understood if the plot of acid gas loading of rich amine is considered. A lower acid gas loading is observed at higher solvent wt% which means that more free solvent molecules are available in the solvent stream to absorb new acid gases. Accordingly, it has a better capability of confronting external disturbances. Also, the effect of the number of stages of the absorption column on the maximum tolerable disturbance is studied. It is concluded that the robustness of the process will decrease against both types of disturbances as the number of stages increases and lower disturbances can be handled without H2S outlet constraint violation.

Kinetic and Thermodynamic Analysis of High-Pressure CO2 Capture Using Ethylenediamine: Experimental Study and Modeling

One of the alternatives to reduce CO2 emissions from industrial sources (mainly the oil and gas industry) is CO2 capture. Absorption with chemical solvents (alkanolamines in aqueous solutions) is the most widely used conventional technology for CO2 capture. Despite the competitive advantages of chemical solvents, the technological challenge in improving the absorption process is to apply alternative solvents, reducing energy demand and increasing the CO2 captured per unit of solvent mass. This work presents an experimental study related to the kinetic and thermodynamic analysis of high-pressure CO2 capture using ethylenediamine (EDA) as a chemical solvent. EDA has two amine groups that can increase the CO2 capture capacity per unit of solvent. A non-stirred experimental setup was installed and commissioned for CO2 capture testing. Tests of the solubility of CO2 in water were carried out to validate the experimental setup. CO2 capture testing was accomplished using EDA in aqueous solutions (0, 5, 10, and 20 wt.% in amine). Finally, a kinetic model involving two steps was proposed, including a rapid absorption step and a slow diffusion step. EDA accelerated the CO2 capture performance. Sudden temperature increases were observed during the initial minutes. The CO2 capture was triggered after the absorption of a minimal amount of CO2 (~10 mmol) into the liquid solutions, and could correspond to the “lean amine acid gas loading” in a typical sweetening process using alkanolamines. At equilibrium, there was a linear relationship between the CO2 loading and the EDA concentration. The CO2 capture behavior obtained adapts accurately (AAD < 1%) to the kinetic mechanism.

Effect of Methane, CO2, and H2S on the Solubility of Methyl and Ethyl Mercaptans in a 25 wt % Methyldiethanolamine Aqueous Solution at 333 and 365 K

We have investigated the solubility of methanethiol and ethanethiol (methyl and ethyl mercaptans in an aqueous methyldiethanolamine solution (25 wt%) by using static-analytic method at 333 and 365K. The measurements were done for different pressure of methane in the absence of acid gas with individual acid gas present, and with mixture of acid gases present (CO2 and/with H2S). Additional measurement of Henry's law constant were realized by considering gas stripping method. Effect of total pressure (realized by addition of methane) and effect of acid gas loading for a constant total pressure around 7 MPa were studied. The increasing of pressure and acid gas loading increase the apparent Henry's law constant of the mercaptan, highlighting a drop out effect of the mercaptans.

Gas sweetening simulation and its optimization by two typical amine solutions: An industrial case study in Persian Gulf region

The selective removal of acid gases using amine-based solutions is a significant process in the petroleum and natural gas industries. This work investigates the effectiveness of two common chemical solvents of Methyl Diethanolamine (MDEA) and Diethanolamine (DEA) and the blends of them with different mass concentration and circulation rate to absorb H2S and CO2 from natural gas in an existing industrial process plant in Phase I of the South Pars Gas Complex (SPGC) located in Persian Gulf region. This sweetening unit was simulated for H2SCO2MDEAH2O and H2SCO2DEAH2O systems incorporated into the Amine Package in the Promax simulator. Sensitivity analyses were performed on circulation rate (140–350 m3/h for MDEA and 300–520 m3/h for DEA), concentration (30–65 wt.% for MDEA and 30–40 wt.% for DEA) of amine solution and the MDEA to DEA ratio (eight different cases) which are the main factors improving process performance. The effect of these factors has been separately studied on the parameters such as acid gas content in the sweetened gas, reboiler duty, acid gas loadings, amine carryover and pH. The results confirmed that higher solvent concentration and circulation rate are beneficial to the sour gas absorption process. However, they require greater corresponding energy to regenerate rich-loaded solution in the reboiler. It enhances the operational costs. Based on the results, the optimal concentration and flow rate of MDEA and DEA solvents was obtained at 40 and 32 wt.% and 150 and 350 m3/h, respectively.

Experimental Measurement of Carbon Dioxide Solubility in Aqueous N-Methyldiethanolamine + 2-(2-Aminoethylamino) Ethanol + Sulfolane and Diethanolamine + 2-(2-Aminoethylamino) Ethanol + Sulfolane Hybrid Solvents at Various Temperatures and High Pressure

The sets of vapor–liquid equilibrium (VLE) data for CO2 solubility in a combination of (N-methyldiethanolamine (MDEA) + 2-(2-aminoethylamino) ethanol (AEEA)) and (diethanolamine (DEA) + AEEA) as a chemical solvent blended with sulfolane as a physical solvent are acquired at 313.15–343.15 K within the CO2 partial pressure range up to 5600 kPa. The measurements are fulfilled for two different hybrid solvents of MDEA + AEEA + sulfolane with the weight compositions of (20–10–10) wt % and (20–10–20) wt % and a mixed solvent of DEA + AEEA + sulfolane with (20–10–10) wt %. It is deduced that CO2 loading was enhanced by substituting the MDEA with DEA, diminishing the temperature, and raising the pressure. Besides, increasing the sulfolane concentration in the aqueous system of MDEA + AEEA + sulfolane leads to enrichment in the effectiveness of the solution in CO2 absorption in the high loading region. In contrast, at low pressures, it adversely affects the acid gas loading. Moreover, it was displayed that at the same total mole of alkanolamines and sulfolane, the CO2 solubilities of AEEA + sulfolane and AEEA + MDEA + sulfolane are higher than those of AEEA + MDEA + sulfolane and MDEA + sulfolane, respectively. Therefore, it could be claimed that AEEA presents a better performance in CO2 capturing than MDEA. Besides, it was demonstrated that AEEA + sulfolane represents a higher capability in CO2 elimination than DEA + AEEA + sulfolane. Thus, the ability of DEA to remove CO2 is lesser than AEEA. Altogether, the degree of alkanolamines’ selectivity toward CO2 is found as AEEA > MDEA > DEA.

High-pressure measurement and thermodynamic modeling of the carbon dioxide solubility in the aqueous 2-((2-aminoethyl)-amino)-ethanol + sulfolane system at different temperatures

In this work, we presented the set of the experimental VLE data of solubility of carbon dioxide in the blend of 2-((2-Aminoethyl) amino) ethanol (AEEA) and sulfolane utilizing a quasi-static high-pressure equilibrium cell. We performed the measurements under isothermal conditions at temperatures of 313.15, 328.15 and, 343.15 K, and up to the maximum pressure of 5500 kPa. We used the various solvent mass compositions of (30–20–50), (30–10–60), (20–20–60), (20–10–70), (10–20–70), (10–10–80) wt% for the AEEA + sulfolane + H2O system. It was found that the CO2 loading in the solvent significantly enhanced by decreasing temperature and increasing pressure. Besides, CO2 solubility was improved by increasing both of sulfolane and AEEA concentration. Nevertheless, at the low CO2 loading region, the acid gas loading was reduced through enhancing the sulfolane concentration. Moreover, it was shown that an aqueous mixture of AEEA + sulfolane has a better performance than an aqueous blend of MDEA + sulfolane for CO2 removal. Furthermore, to model the CO2 solubility in the mixtures, a robust thermodynamics model based on the E-NRTL function was employed to correlate and predict the partial pressure of CO2 against its loading. The reasonable agreement between the calculated and experimental results demonstrated the high accuracy of the present thermodynamic modeling.

Modeling and Simulation of the Simultaneous Absorption/Stripping of CO2 with Potassium Glycinate Solution in Membrane Contactor.

Global warming is an environmental problem caused mainly by one of the most serious greenhouse gas, CO2 emissions. Subsequently, the capture of CO2 from flue gas and natural gas is essential. Aqueous potassium glycinate (PG) is a promising novelty solvent used in the CO2 capture compared to traditional solvents; simultaneous solvent regeneration is associated with the absorption step. In present work, a 2D mathematical model where radial and axial diffusion are considered is developed for the simultaneous absorption/stripping process. The model describes the CO2/PG absorption/stripping process in a solvent–gas membrane absorption process. Regeneration data of rich potassium glycinate solvent using a varied range of acid gas loading (mol CO2 per mol PG) were used to predict the reversible reaction rate constant. A comparison of simulation results and experimental data validated the accuracy of the model predictions. The stripping reaction rate constant of rich potassium glycinate was determined experimentally and found to be a function of temperature and PG concentration. Model predictions were in good agreement with the experimental data. The results reveal that the percent removal of CO2 is directly proportional to CO2 loading and solvent stripping temperature.

Effectiveness of Amine Concentration and Circulation Rate in the CO2Removal Process

AbstractOptimization of an amine‐based method is vital to ensure product quality, equipment safety, and system efficiency. Here, the effectiveness of amine concentration and circulation rate is evaluated for a diglycolamine (DGA)‐based facility. The performance is measured using the concentration of carbon dioxide in the treated gas and the net acid gas loading of the amine solution. Both amine concentration and circulation rate were observed to affect the system efficiency. An optimal operating range was identified for the gas plant studied established on the performance criteria. The analysis is based on a proprietary mass transfer‐based process simulator of an amine‐based acid gas treating facility and field data.

Novel AGR-EOR Compression Integration for Process Optimization

Summary In this work we aim to enhance the sour-gas loading in acid-gas removal (AGR) systems, maximizing oil-production rate at the tertiary phase and enhanced oil recovery (EOR), and mitigating vented carbon dioxide (CO2) with minimal modification to the existing systems. We conducted a simulation study on the basis of a real natural-gas liquids (NGLs) plant and Qatari oil wells with a 390-MMscf/D feed of sour gas using HYSYS and ProMax process simulation tools to evaluate the novel configurations compared with a conventional AGR system. The results show that the acid-gas loading improved from 0.48 to 0.81, and the amine circulation rate decreased by 40%, while maintaining the treated-gas quality specifications (4 ppm H2S, 1 mol% CO2). The required CO2 compression power for CO2-EOR decreased by 15.49%, and the oil production was enhanced by 1,360 B/D. In addition, 13.6 MMscf/D of CO2 is mitigated and used rather than vented.

Implementation of electrolyte CPA EoS to model solubility of CO2 and CO2 + H2S mixtures in aqueous MDEA solutions

Abstract The electrolyte version of SRK plus association equation of state (eSRK-CPA EoS) was employed to correlate CO2 solubility in MDEA aqueous solutions. The applied model comprises the classic form of CPA EoS including SRK EoS plus Wertheim association term in addition to MSA theory and Born terms so that the two last terms are responsible for the long-range interactions. A reaction-containing bubble pressure computation technique comprising two nested loops was utilized to model the systems. The internal loop, calculates the liquid phase concentrations via reaction, mass and charge balance equation solving, whereas, the vapor phase concentrations will be obtained in the external one. 470 experimental data were used to correlate binary subsystems and the H2O + MDEA + CO2 ternary system. Since, there not exist any binary VLE data for MDEA + CO2 subsystem, two fitting scenarios were applied. At the first scenario, the binary interaction parameter was assumed equal to zero, while, in second approach the parameter was obtained through ternary system correlation. Both scenarios show very good accuracy in that the Absolute Average Deviation percentages (AAD) obtained were 19.12% and 18.85%, respectively. Also, to show the efficiency of the used model, a comparison between our results and those of the best-known models was made. Finally, having model parameters for H2S solubility from our previous work [A. Afsharpour, Petroleum Science and Technology 35 (3) (2017) 292-298], simultaneous solubility of CO2 + H2S mixtures in MDEA solutions was predicted using the eSRK-CPA EoS with no new optimizable parameters. As the results show, the applied model has a good performance for correlation and prediction of acid gas solubility in a wide range of pressures, temperatures, acid gas loadings, and MDEA concentrations.

Revamping of an acid gas absorption unit: An industrial case study

This work evaluates the efficiency of the aqueous mixture of Methyl Diethanolamine (MDEA) and Diethanolamine (DEA) at various mass concentrations to remove CO2 and H2S from natural gas in an industrial sweetening unit in Fajr Jam Gas Refining Company located in the south of Iran and gives recommendations for modifying the process. The sweetening unit includes absorber and desorption towers, flash drum, lean and rich amine exchanger, kettle type reboiler and a reflux drum. The considered process is simulated by Promax simulator (version 3.2) taking into account operational constraints and sustainability of the environment. The validity of simulation has been evaluated by comparison between simulation results and the plant data. The main objective of this work is the modification of natural gas sweetening unit to achieve lower energy consumption. Thus, the effect of amine circulating rate and MDEA to DEA ratio on steam consumption in the regeneration tower, CO2 and H2S concentration in the treated gas, and the acid gas loadings have been investigated. Therefore, substitution of DEA solvent in the unit with the aqueous mixture of DEA and MDEA is proposed. In the examined cases, the mass concentration of MDEA and DEA lies between 15 and 45 wt% and 0–30 wt%, respectively, with the reference cases having MDEA 0 wt% and DEA 31.6 wt%. The results show that in the proposed cases of alternative mixtures including cases 1 (MDEA15 wt% and DEA 30 wt%), 2 (MDEA 20 wt% and DEA 25 wt%), and 3 (MDEA 25 wt% and DEA 20 wt%) the amount of reduction in amine circulation rate are between 11.1%v/v and 19.4%v/v compared to the original amine circulation rate. Likewise, steam consumption decreases between 24.4 %wt/wt and 27 %wt/wt. Influence of anti-foam injection for the different cases were also studied and it was found that anti-foam with the concentration of 5000 ppmv is more suitable for the optimum operation and is a more cost effective.

Measuring and correlating solubility of hydrogen sulfide in aqueous solution of 2-((2 aminoethyl)amino)ethanol

The solubility of hydrogen sulfide (H2S) in aqueous solution of 2-((2-aminoethyl)amino)ethanol (AEEA) at low and medium pressures was determined for two different concentrations (i.e. 10 and 30 wt%). The experimental total pressure varied from (9.5 to 1594) kPa and the experimental temperature was set to (313.2, 328.2, 343.2 and 358.2) K. The experimental data are presented as the total pressure against acid gas loading (mole H2S per mole of AEEA). The Deshmukh-Mather model and Peng-Robinson equation of state were used for the liquid and vapour phase, respectively, to correlate the solubility of H2S in aqueous solutions of AEEA. The average absolute deviation percent (AAD%) in calculating the total pressure as a function of H2S loading obtained 5.0% for (AEEA– H2O–H2S) ternary system at the four values of temperature. The enthalpy change of the absorption of H2S in the 10 and 30 wt% aqueous solution of AEEA was also estimated with the tuned model.

Enhancing gas loading and reducing energy consumption in acid gas removal systems: A simulation study based on real NGL plant data

Amine scrubbing with absorption and desorption is the most established technology for Acid Gas Removal (AGR) systems, but suffers from high regeneration energy requirements and, hence offers a good opportunity for more development. A simulation study has been carried out based on a local NGL plant data to evaluate the performance parameters for AGR systems along with energy and utility consumptions for all single alkanolamines (Primary, Secondary and Tertiary) as well as the MDEA/PZ amine blend with different concentrations. The ultimate aim of the study is to address the critical industrial limitations in AGR systems, understand the individual performance for each amine under the same conditions and to investigate the Benchmark amine blend (MDEA + PZ) to optimize the absorption process in terms of enhancing acid gas loading and lowering the regeneration energy consumption. Ten cases have been investigated under the same conditions, where MDEA/PZ with 20/10 wt% has shown a better performance among single amines and benchmark amine blend 29/1 wt%; it could save 8% in steam consumption, 45% in cooling water, 62% in Lean Amine Air cooler, 45% in pumping power and 38% in solvent circulation rate, in addition to enhancing acid gas absorption by 67%.

Measuring the Density and Viscosity of Carbonated Aqueous 35 wt% Methyldiethanolamine Solution

The density and viscosity of carbonated aqueous 35wt% methyldiethanolamine solution were experimentally measured accompanied with the solubility of CO2 at temperatures from (303.15 to 363.15) K and pressures up to 0.8 MPa using the new setup developed in our laboratory.It was observed that both density and viscosity of mixtures decrease by increasing temperature and increase by increasing acid gas solubility (loading) in solution. Acid gas loading has an intense effect on the viscosity of solutions than on their density. The modified Seth now correlation was used to predict the density and viscosity of all solutions studied in this work.

Modeling of H2S solubility in aqueous MDEA solution using electrolyte SRK plus association equation of state

ABSTRACTH2S solubility in MDEA aqueous solution at different solution compositions, temperatures, pressures, and acid gas loadings was correlated using electrolyte SRK-cubic plus association equation of state. A total of 302 experimental data were used in this work. At first pure components parameters were obtained from literatures. Then binary interaction parameters were calculated through binary subsystems investigation. Finally, ternary system modeled using a reactive bubble point pressure calculation method. Considering number of binary interaction parameters that should be optimized, three scenarios were proposed. All of the scenarios present good results with acceptable absolute average deviation percentage (AAD%) but the third one shows better outputs. The AAD% in this scenario is 17.02.

Correlation of H2S solubility in aqueous MDEA solutions using electrolyte-modified Peng-Robinson plus association equation of state

ABSTRACTIn this survey, we use the emPR-CPA equation of state to model a ternary system of H2S solubility in MDEA aqueous solution at different solution compositions, temperatures, pressures, and acid gas loadings. For electrolyte part of the model, MSA theory and the Born term were used. There were 302 experimental data used in this work. To model a ternary system, at first pure components, then binary subsystems, and finally ternary system were modeled using a reactive bubble point pressure calculation method. An overall absolute average deviation percentage equal to 20.85 was achieved so that show the model efficiency for correlation of such systems.

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.

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.