Amine Blends Research Articles

Physicochemical and thermodynamic properties of aqueous blends of 3-aminopropyl triethoxysilane and amines at 298.15–333.15 K

We report the density, viscosity, sound velocity, and refractive index experimental data of four silane–amine blended systems viz. (1) 3-aminopropyl triethoxysilane (TESA) + N-(2-aminoethyl) piperazine (AEP), (2) 3-aminopropyl triethoxysilane (TESA) + 2-methyl-1-propanol (AMP) (3) 3-aminopropyl triethoxysilane (TESA) + Methyldiethanolamine (MDEA) and (4) 3-aminopropyl triethoxysilane (TESA) + Diethanolamine (DEA). The temperature range for all the measurements is (298.15–333.15) K up to a mole fraction of 0.2 of TESA in the solution. The physicochemical properties were well fitted against the first principle and artificial neural network models. We further calculated key properties for CO2 capture such as diffusivity in CO2, isentropic compressibility, thermal expansion coefficients, Gibb's free energy, entropy, and enthalpy of activation. The data collected from this work could contribute to further detailed kinetic analysis of CO2 absorption over these capturing solvents

Impact of blends of aqueous amines on absorber intercooling for post combustion CO2 capture system

Climate change is the biggest challenge of this century due to the global consequences of human activities on the ecosystem resulting in global warming. The emissions of greenhouse gases, mainly CO2 from the combustion of fossil fuels in the power plant is the main cause of global warming and to mitigate these emissions is the foremost challenge. Nowadays, the most preferred method is post combustion chemical absorption using amine-based solvents. However, high energy requirements for this method restrict its deployment. An efficient approach used for the reduction of the high energy requirement of post combustion CO2 capture process was absorber intercooling. Therefore, this research evaluates the effect of two configurations of intercooled absorber such as “simple” and “advanced” intercoolers for CO2 capture integrated with natural gas combined cycle power plant using aqueous alkanolamines, such as 30 wt.% monoethanolamine and 50 wt.% methyl-diethanolamine and their blends. For pure methyl-diethanolamine case, at lean loading 0.01 intercooling configurations; simple and advanced shows the highest reduction of 21.01% and 22.82% in the specific reboiler duty, respectively in comparison to other blends at the expense of highest liquid solvent flow rate. Simple and advanced intercooling configurations shows optimum results for the case with 40% monoethanolamine and 60% methyl-diethanolamine in a blend with decrease of 9.19% and 17.28% in solvent flow rate and a decrease of 9.42% and 16.83% in specific reboiler duty required for 90% CO2 capture rate, respectively. For pure monoethanolamine case at lean loading 0.2 absorber intercooling does not offer significant results.

Thermodynamic modeling and new experimental CO2 solubility into aqueous EAE and AEEA blend, heat of absorption, cyclic absorption capacity and desorption study for post-combustion CO2 capture

In the present study, carbon dioxide (CO2) solubility into aqueous blend of 2-(ethylamino) ethanol (EAE) and aminoehtylethanolamine (AEEA) was measured. The performance of CO2 capture by this amine blend was investigated in terms of CO2 solubility, heat of absorption, cyclic CO2 solubility, and initial rate of change of CO2 solubility. CO2 absorption study was carried out using bubble column reactor in the temperature range of 298.15 to 323.15 K, 8.11 to 20.27 kPa CO2 partial pressure, 0.10 to 0.30 wt fraction of AEEA in EAE and AEEA blend, and 10 to 30 wt% total concentration of blend solution. Desorption experiments were performed at 393.15 K. Maximum CO2 solubility was 1.033 mol CO2/mol amine at 298.15 K, 20.27 kPa, 0.30 wt fraction of AEEA in the blend, and 10 wt% of EAE and AEEA solution. A semi-empirical Kent-Eisenberg thermodynamic model and an empirical model were developed to calculate equilibrium CO2 solubility in the studied range of operating conditions with 2.56% and 0.45% average absolute deviation, respectively. At 313.15 K, 15.20 kPa CO2 partial pressure and total concentration of 30 wt% of EAE and AEEA blend, the equilibrium CO2 solubility was resulted as 0.748 mol CO2/mol amine and cyclic solubility of 0.503 mol CO2/mol amine was achieved. Heat of CO2 absorption was measured based on Gibbs Helmholtz equation and found as −72.25 kJ/mol for 30 wt% aqueous EAE and AEEA blend. Results of absorption capacity of EAE and AEEA solution and monoethylethanolamine (MEA) were compared at same operating conditions. This blend had higher CO2 solubility, lesser heat of absorption, more cyclic capacity and faster rate of change of initial CO2 solubility than MEA.

The Effects of Amine Type and Lean Amine Temperature on Gas Sweetening Processes

In the North Gas Company (NGC) in Kirkuk, Iraq, sour gas stream is loaded with considerable amounts of H2S and CO2 of 2.95% and 2.54%, respectively. A DEA amine system is currently used to reduce these sour component concentrations below 5 ppm and 2% for H2S and CO2, respectively. This study used Bryan Research and Engineering’s ProMax® process simulation software to optimize this amine sweetening system by adopting other amine types and blends, such as methyldiethanolamine (MDEA). It could be argued that a 50 wt% MDEA solution circulated at 414 m3/h was determined to be the optimum operating conditions. This design met sweet gas specifications and minimized the reboiler duty to 38 MW, 30.9% reduction in steam consumption. The experimental simulation work is also examined the effects of lean solvent temperature on the gas sweetening process efficiency and performance and find out that the lean amine temperature within the range of 43–48°C in all sceneries give acceptable sweetening results.

CO2 capture performance and mechanism of blended amine solvents regulated by N-methylcyclohexyamine

Blended amine solvents are considered potential alternatives to monoethanolamine for CO2 capture, for the fast absorption kinetics of primary/secondary amine and low regeneration penalty of tertiary amine. In this research, blended amine solvents comprising N,N-dimethylcyclohexylamine (DMCA) and N-methylcyclohexyamine (MCA) were proposed. CO2 absorption increased the polarity of the products and ensured the absorbent remained homogenous throughout the absorption/desorption cycles. Through quantum chemical calculation, the low stability of MCA-carbamate was confirmed by a ΔΔG3 value of −6.41 kcal/mol, and a possible reaction route from carbamate to bicarbonate was revealed. Thus, the CO2 capacity of DMCA-MCA reached 0.875–0.985 mol CO2/mol amine. Moreover, MCA exhibited considerably low forward energy barrier for zwitterion formation (2.7 kcal/mol), and the CO2 absorption of DMCA could be accelerated through the proton transfer reaction with the MCA-zwitterion. Accordingly, the total mass transfer coefficient of CO2 in DMCA-MCA approached 2.02 × 10−10 mol/cm2 s Pa, which was 1.2-fold higher than that of 5 M MEA. The total regeneration energy of DMCA-MCA blend was estimated at 2.20 GJ/t CO2, which was 44.9% lower than 5 M MEA. This study developed a novel DMCA-MCA blended solvent with rapid absorption rate, huge CO2 capacity and efficient regeneration for CO2 capture.

Equilibrium CO2 solubility in the aqueous mixture of MAE and AEEA: Experimental study and development of modified thermodynamic model

In the present study, equilibrium solubility of CO2 was studied in the aqueous blend of 2-(methylamino)ethanol (MAE) and aminoethylethanolamine (AEEA). Total concentration of blend solution, weight fraction of AEEA in aqueous (MAE+AEEA) blend, temperature, and partial pressure of CO2 was varied from 10 to 30 wt %, 0.10 to 0.30, 298.15 to 323.15 K, and 8.11 to 20.67 kPa, respectively. Maximum loading 0.944 mol CO2/mol amine was occurred at 298.15 K, 20.27 kPa of CO2 partial pressure, 10 wt % total concentration with 0.30 wt fraction AEEA. The Kent-Eisenberg thermodynamic model was modified by incorporating newly introduced correction factor (Fk) to predict CO2 solubility in the aqueous blend of MAE+AEEA. Experimental data and model predicted data was in good agreement with each other. In addition, heat of CO2 absorption was also calculated for this amine blend and reported as -73.43 kJ/mol.

Heat of absorption of CO2 in aqueous solutions of DEEA and DEEA + MAPA blends—A new approach to measurement methodology

The heat of absorption is an important parameter that affects the CO2 absorption and stripping performance of amine-based CO2 capture. The present paper aims at development of the experimental method of determining the heat of absorption using a batch reaction calorimetry. A prospective high‐capacity CO2‐capturing solvent based on an aqueous solution of N,N-diethylethanolamine (DEEA) blended with small concentrations of 3-(methyloamino)propylamine (MAPA) is therefore studied. The differential and integral heat of absorption of CO2 was measured at 40 °C and 60 °C using single DEEA and amine blends. Experiments show that the heat of absorption in DEEA and DEEA + MAPA blends depends both on loading and temperature, though the temperature dependency is not as high as reported earlier. Increasing the MAPA/DEEA concentration ratio increased the heat of absorption in the amine blends.

Elucidating the performance of (N-(3-aminopropyl)-1, 3-propanediamine) activated (1- dimethylamino-2-propanol) as a novel amine formulation for post combustion carbon dioxide capture

The exploration of energy-efficient amine solvents for CO2 removal from fluegas streams has been adopted as a key strategy for the wide implementation of CO2 capture technology in fossil fuel-based power plants for post-combustion CO2 capture. The current study entails an insight into the CO2 absorption performance of a novel aqueous amine blend of N-(3-aminopropyl)-1,3-propanediamine (APDA) and 1-dimethylamino-2-propanol (1DMAP) with special emphasis to the investigation of CO2 solubility at equilibrium state. In order to investigate the effect of promoter addition, the concentration of APDA has been gradually increased from 0.02 w to 0.10 w in the mixed solvent blend. The generated solubility data are correlated using two different modeling approaches viz., equilibrium based modified form of Kent-Eisenberg (KE) thermodynamic model and feed-forward neural network model. The model prediction is further extended to estimate pH and the overall speciation profile of all the molecular as well as ionic species prevailing in the solvent system. The CO2 solubility data are also analyzed in view of estimating the heat duty requirement for the absorption process. The heat of absorption of CO2 in aqueous (APDA + 1DMAP) blend has been calculated using theGibbs-Helmholtz equation. Along with solubility measurement, important thermophysical properties such as density and viscosity of the aqueous amine solution are also measured and correlated using established Redlich-Kister and Grunberg Nissan models.

Techno-economic analysis of acid gas removal from associated and non-associated sour gas using amine blend

Acid gas removal (AGR) is a critical step in the supply chain of natural gas for its safe transmission and clean combustion. Chemical amines are the most commonly employed commercial solvents for the gas cleaning. Due to energy intensive nature of the AGR process, ways to improve process efficiency are vital. This study investigated the removal of acid gases from the associated and non-associated sour feeds using a blend of diglycolamine (DGA) and methyldiethanolamine (MDEA) solvents at a total strength of 50 wt. %. Steady-state process simulation models have been developed to seek the process improvement by utilization of amine blends. The study performed a detailed energy and economic analysis to understand the feasibility of the investigated amine blends. The results show that when 45 wt. % DGA is mixed 5 wt. % MDEA additive for the processing of associated gas, a saving of 3.42 $/MMSCF of sweet gas produced is achieved. On the other hand, cost per MMSCF of sweet gas increases significantly when DGA additive is mixed with MDEA amine for the processing of non-associated gas.

Effect of Various Parameters on the Thermal Stability and Corrosion of CO2-Loaded Tertiary Amine Blends

In this study, the thermal stability and corrosivity of various CO2-loaded tertiary amine blends in both aqueous and non-aqueous form in stainless steel cylinders were studied for combined acid gas and water removal. The thermal stability was measured from the remaining amine concentration and the corrosivity was measured from the amount of various metals in blends using titration and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The experimental data were used to calculate the rate constants of amine group loss. The developed model represented the experimental data very well. Solvent change from H2O to triethylene glycol (TEG) in blends decreased the thermal stability and vice versa for corrosivity. The amine stability was increased when contact with stainless steel was reduced. An increase in the amine concentration or CO2 loading at constant temperature decreased the thermal stability and vice versa for corrosivity.

Viscosity Measurement and Correlation of Unloaded and CO2-Loaded Aqueous Solutions of N-Methyldiethanolamine + 2-Amino-2-methyl-1-propanol

This work contributes to new and complementary experimental viscosity data for blended amine mixtures of aqueous N-methyldiethanolamine + 2-amino-2-methyl-1-propanol (MDEA + AMP) solutions with and without CO2 at different temperatures and mass fractions. For the unloaded MDEA + AMP solutions, measurements were conducted with total amine mass fractions ranging from 0.30 to 0.60. In the case of CO2-loaded aqueous MDEA + AMP solutions, experiments were performed at CO2 loadings ranging from 0.11 to 0.80. Proposed correlations were used to represent viscosity at the unloaded and CO2-loaded solutions within experimental uncertainty.

A novel blended amine functionalized porous silica adsorbent for carbon dioxide capture

In order to accomplish efficient CO2 capture, poly(ethyleneimine) (PEI) and tetraethylenepentamine (TEPA), with commonly used and inexpensive, was codispersed into the as-prepared SBA-15 (SBA-15(p)) to prepared blended amine functionalized adsorbent. The influence of the mass ratio of PEI to TEPA on the adsorption property was investigated. The promoting effects of TEPA on CO2 capture property were investigated. The adsorbents were characterized using N2 adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and in situ diffuse reflectance infrared fourier transform spectroscopy (in situ DRIFTS). Among the prepared adsorbents, the SBA-15(p) with 30 wt% PEI and 40 wt% TEPA has the CO2 capture capacity of 4.64 mmol/g and the optimal amine efficiency (0.359 molCO2/molN) at 75 °C with 20 vol% CO2 in N2. The addition of TEPA species could improve the CO2 adsorption amount with high amine utilization. The P123 with wheel-like distribution in SBA-15(p) promotes the CO2 capture by optimizing the accessibility of amine to the CO2. After 15 adsorption cycles, the SBA-15(p) with 40 wt% PEI and 30 wt% TEPA has better reusability and cyclic performance, the adsorption capacity can keep around 4.13 mmol/g. The result indicated that more PEI in the adsorbent would improve the adsorbent cyclic stability. Meanwhile, the in-situ DRIFTS results suggested that the reaction of CO2 molecule with the amine active sites in the adsorbent, agrees with anionic and cationic mechanisms.

Strain rate sensitivity of polyurea coatings: Viscous and elastic contributions

Polyurea, a reaction product of isocyanates and an amine blend has been reported to be highly strain rate sensitive, which responds in its own unique way when subjected to increasing strain rates. The amine blend comprise of a long chain amine, forming the soft segments, chain extender, which brings the urea linkages closer and a crosslinker, which serves as a chemical bond between the chains. In this work, we attempt to tune the viscous contribution in polyurea, by increasing crosslinking density, while keeping the amount of chain extender more or less constant. The viscoelastic behavior and its effect on the time dependant behavior was established by extensive dynamic studies. Quasi-static tests and Split Hopkinson testing was performed over large deformation rates (10−4 to 103 s−1). It was observed that polyureas with larger viscous contribution (tan δ), were capable of exhibiting larger strain rate sensitivity.

Amine-based solvent for CO2 absorption and its impact on carbon steel corrosion: A perspective review

Carbon dioxide (CO2) is one of the commonly emitted gaseous by-products in industrial processes. While CO2 gas is the main cause to greenhouse effect, various CO2 capture technologies have been proposed and implemented to sequester the CO2 before the waste gases being released into the atmosphere. One of the mature technologies for CO2 absorption is by using amine-based solvents. In this regard, different single amine solvents or blended amine solvents have been proven for their capability to remove CO2. However, the dissolution and reaction of CO2 gas with the amine solvents turn the solution corrosive. Such phenomenon is undesired as it posts corrosion problem to the absorption column, which normally built of carbon steel material. Henceforth, understanding the behaviour of different amine-based solvents in absorbing CO2 and its subsequent impact on carbon steel corrosion is very significant. In this review article, we will outline some of the more commonly used solvents and their respective advantages and disadvantages, motivating further investigation into the corrosion tendency. Meanwhile, existing gaps in this research area are discussed for future investigation.

An effective hybrid solvent of MEA/DEEA for CO2 absorption and its mass transfer performance in microreactor

The gas-liquid two-phase flow and the mass transfer characteristics for CO2 absorption into the binary amine mixture of monoethanolamine (MEA) and N,N-diethylethanolamine (DEEA) aqueous solution were investigated in T-junction microchannel reactor with a square cross-section. The effects of gas-liquid flow rate and absorbent concentration on bubble length, velocity and mass transfer coefficient were studied. Three flow regimes including slug-bubbly flow, slug flow and slug-annular flow were observed under experimental condition, and the gas-liquid two-phase flow pattern map was depicted. It is found that the transitions between three flow regimes depend primarily on the competition of forces exerted on bubble in the T-junction. The kinetics of CO2 absorption into blended amine aqueous solutions was analyzed to understand the mass transfer enhancement mechanism of new hybrid solvent. Furthermore, the liquid-side overall mass transfer coefficient kL and the liquid-side overall volumetric mass transfer coefficient kLa were determined through processing experimental images recorded by a high-speed camera. The results show that kLa is in the range of (3.04–20.07) s−1 in this work, which is 2–3 orders of magnitude higher than that in the conventional equipment. The dimensionless Damköhler number (Da) and Peclet number (Pe) are introduced to correlate the liquid-side volumetric mass transfer coefficient, new correlation shows good prediction accuracy with the average deviation of 3.64%.

Sulfolane and di-iso-propanol lean amine blend operating temperature and pressure effect to natural gas sweetening using process simulation

Blending physical and chemical solvents has shown to be promising for removing hydrogen sulfide, carbon dioxide and mercaptan from natural gas effectively. Studies show that using sulfolane and methyl di-ethylene amine blend yields better performance than traditional methods. However, the Shell process depicts that blending sulfolane with di-iso-propanol amine significantly minimizes the problem associated with amine re-circulation efficiency observed with the application of sulfolane and methyl di-ethylene amine. This study aimed at investigating the effect of temperature and pressure to the acid gas removal performance of sulfolane and di-iso-propanol lean solvent using Aspen HYSYS software. In addition, the determination of optimum blend ratio was considered. The acid gas composition of the natural gas stream was 16.9%. This is a hypothetical data used to mimic a relatively high acid gas content in a typical raw natural gas feed. During the process simulation, the lean solvent temperature and pressure were varied between 5 and 210 °C, and 20 and 250 bar, respectively, while maintaining the reactant flow rate at 819.5 kg/h. Findings informs that the optimum blend formulation obtained was 15% water, 15% sulfolane and 70% di-iso-propanol amine at operating temperature and pressure of 50 °C and 45.5 bar, respectively. At the end of the process, the acid gas composition reduced from 16.9 to 0.26%, with an increase in the methane composition by 16.12%. This was as a result of the reduction in the vapor point of the lean solvent, which significantly contributed to enhancing the contact time and efficiency between the gas feed and lean solvent. Hence, the sales gas specification for natural gas was met at lower operating temperature and pressure below 10 °C and 25 bar, respectively.

Selection of efficient absorbent for CO2 capture from gases containing low CO2

Amine-based absorption processes are widely used in natural gas processing, but recently they have been considered for CO2 capture from flue gas emitted from thermal power plants. The main issue of amine used in the CO2 capture process is the high cost of solvent regeneration. So, this issue can be solved by using efficient amine absorbent. The amine type absorbents employed in the experimentation were an aqueous blend of 2-(Diethylamino)ethanol (DEEA) with different types of diamine activators such as piperazine (PZ), 2-(2-aminoethylamino)ethanol (AEEA), hexamethylenediamine (HMDA), ethylenediamine (EDA), and 3-(Dimethylamino)-1-propylamine (DMAPA). An absorption experiment was performed to evaluate the CO2 absorption performance in terms of CO2 loading, absorption capacity, and absorption rate. The experiment was performed to assess the CO2 desorption performance in terms of desorption capacity, desorption rate, cyclic capacity, and regeneration efficiency. From the results of absorption-desorption and comparison with benchmark amine absorbent MEA, the aqueous blend of DEEA and HMDA indicated the best performance for CO2 capture applications among all the tested amine blends.

Simulation of an Acid Gas Removal Unit Using a DGA and MDEA Blend Instead of a Single Amine

Abstract Most of the industrial acid gas removal (AGR) units employ chemical absorption process for the removal of acid gases from the natural gas. In this study, two gas processing plants operational in Saudi Arabia have been selected where two different amines n1amely, diglycolamine (DGA) and monoethanol amine (MDEA) are used to achieve the sweet gas purity with less than 4 ppm of H2S. This study performed a feasibility simulation of AGR unit by utilizing the amine blend (DGA+MDEA) for both plants instead of a single amine. The study used a commercial process simulator to analyze the impact of process variables such as amine circulation rate, amine strength, lean amine temperature, regenerator inlet temperature, and absorber and regenerator pressure on the process performance. The results reveal that when the MDEA (0–15 wt. %) is added to DGA, marginal energy savings can be achieved. However, significant operational energy savings can be made when the DGA (0–15 wt. %) is blended with MDEA being the main amine.

CO2 capture using aqueous 1-(2-Hydroxyethyl) piperidine and its blends with piperazine: Solubility and enthalpy

In this article, equilibrium CO2 solubility in aqueous 1-(2-Hydroxyethyl) piperidine (HEP) solutions pertaining concentrations (1, 2, 3) mol/L in the temperature range (303.15–323.15) K, and CO2 partial pressure range 0.1–100 kPa are presented. HEP; being a tertiary alkanolamine, its rate of CO2 absorption is comparatively slower than primary or secondary alkanolamine. Piperazine (PZ), a rate promoter was added to HEP in 1:4 mol ratio to form blends having enhance rate of CO2 absorption. Equilibrium CO2 solubility in four different aqueous blends; (0.8 mol/L HEP + 0.2 mol/L PZ), (1.6 mol/L HEP + 0.4 mol/L PZ), (2.4 mol/L HEP + 0.6 mol/L PZ), (3.2 mol/L HEP + 0.8 mol/L PZ) were measured over the temperature range of (303.15–323.15) K and CO2 partial pressure spanning over 0–70 kPa. Equilibrium constant for deprotonation reaction of HEP was estimated by measuring pKa of aqueous HEP solution at 298.15, 303.15, 313.15, 323.15 and 333.15 K. Experimentally obtained CO2 solubility data for single and blended amine solutions were correlated efficiently using activity coefficient model with AAD % of 3.76 and 3.22, respectively. Speciation of both single and blended amine solutions in their equilibrated liquid phase were predicted. Interaction parameters obtained through thermodynamic modelling of equilibrium solubility data for single and blended amine solutions were used to predict the enthalpy of CO2 absorption.

Equilibrium Solubility Measurement and Modeling of CO2 Absorption in Aqueous Blend of 2-(Diethyl amino) Ethanol and Ethylenediamine

The equilibrium CO2 solubility in an aqueous blend of 2-(diethyl amino) ethanol (DEEA) and ethylenediamine (EDA) was performed at atmospheric pressure with the use of a laboratory scale bubbling absorber. The total concentration of amine blend solution in the range of 1.13–4.90 mol·kg–1 and the EDA mole fraction in the total amine blend in the range of 0.05–0.20 were taken. The experiments for the measurement of CO2 solubility were performed at a temperature range of 303.15–333.15 K and CO2 partial pressure range of 10.13–20.27 kPa. The analysis of CO2 in the liquid phase was accomplished by a direct titration method using HCl solution. The solubility data of CO2 in DEEA+EDA solution of the present study were compared with data available in the literature. The experimental results were applied to develop an empirical mathematical model with an average absolute deviation of 7.03% to predict the CO2 equilibrium solubility in DEEA+EDA solution within the specified range of operating conditions. In addition, ...