Carbon dioxide chemical absorption by solvents based on diamine and amines blend

Present work includes research about the influence of the type of amino group using one or two amine molecules on carbon dioxide chemical absorption using aqueous solutions of alkanolamines and diamines. A comparison of chemical absorption processes using aqueous solutions of two individual diamines (3‐(dimethylamino)propan‐1‐amine and 1,3‐diaminopropane) and a mixture of amines (3‐amino‐1‐propanol and 3‐(dimethylamino)propan‐1‐ol) is reported including absorption rate curves, carbon dioxide loading, reaction mechanism or solvent regeneration to obtain useful information about the quality of each solvent for carbon dioxide separation. In general, amines blend of 3‐amino‐1‐propanol and 3‐dimethylamino‐1‐propanol, have shown a better behavior than their individual amines. Diamines and mainly 3‐dimethylamino propylamine that presents primary and tertiary amine groups in its structure, have led similar results. After these studies, 3‐dimethylamino propylamine, can be considered an appropriated amine to industrial carbon dioxide absorption process. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2702–2710, 2018     

CO2 Absorption into Aqueous Solutions of a Polyamine (PZEA), a Sterically Hindered Amine (AMP), and their Blends

Among numerous techniques existing for reducing CO₂ emissions, CO₂ capture by absorption in aqueous alkanolamine solutions was specifically studied in this work. For the choice of the adequate amine solution, two major criteria must be taken into account: absorption performances (higher with primary and secondary amines) and energy costs for solvent regeneration (more interesting with tertiary and sterically hindered amines). The different types of amines can also be mixed in order to combine the specific advantages of each type of amines, an activation phenomenon being observed. Aqueous solutions of (piperazinyl‐1)‐2‐ethylamine (PZEA, a polyamine known as absorption activator) and 1‐amino‐2‐propanol (AMP, a sterically hindered amine), pure or mixed with other amines, are experimentally compared with respect to CO₂ removal performances by means of absorption test runs achieved in a special gas‐liquid contactor at 25 °C. The positive impact of addition of PZEA to monoethanolamine (MEA), N‐methyldiethanolamine (MDEA), and AMP solutions was clearly highlighted. The absorption performances have also been satisfactorily simulated with coherent physicochemical data.     

Factors Influencing Phase Disengagement Rates in Solvent Extraction Systems Employing Tertiary Amine Extractants

Abstract

Phase disengagement rate is a critical property in determining the usefulness of a particular solvent extraction system in hydro-metallurgy. A survey of a number of commercial tertiary amine extractants of the type used in uranium extraction hydrometallurgy has been carried out to suggest whether structural factors influence phase disengagement behavior and to provide a useful comparison of different amines with regard to phase disengagement and uranium extraction. The amines ((C_nH_2n+1)₃N) were chosen to cover a range of alkyl chain lengths including straight-chain and branched-chain compositions, and the chemical makeup of the liquid-liquid systems closely paralleled that of the systems used in the Amex uranium extraction process. Batch phase disengagement tests showed significant trends with respect to amine structure and composition using acid sulfate solutions with or without added colloidal silica and actual ore leach solutions as the aqueous phase. In general, organic continuous (OC) phase disengagement became slower with increasing n (number of carbons per chain) whether branched or linear chain, but for any given n, the branched chain amines had much faster OC phase disengagement than the linear chain amines. A key structural factor affecting OC phase disengagement was found to be the backbone chain length (longest chain in each alkyl group) since the OC phase disengagement measurements could be correlated vs backbone chain length on a single curve regardless of whether the amine was branched or linear. Aqueous continuous (AC) phase disengagement rate was rapid for the acid sulfate solution but decreased greatly with decreasing for the acid sulfate solution but decreased greatly with decreasing n when colloidal silica was added or when leach solution was used. With both leach and colloidal silica solutions, AC phase disengagement was correlated with wetting behavior or the amine systems on a glass (silicate) surface. A model based on silica attachment to the liquid/liquid interface was suggested to explain the stabilization of AC dispersions by silica and the related problem of interfacial crud formation. In addition to faster AC phase disengagement and less emulsion (crud) stabilization, the larger molecular weight amines (n ≥ 10) were found to have higher uranium extraction coefficients and lower tendencies to form third phases. Presumably, solubility losses to the aqueous phase are also lower. The results suggest that the performance of some Amex systems may be improved by using branched chain tertiary amine extractants of higher molecular weight than are now normally used.     

The development of kinetics model for CO2 absorption into tertiary amines containing carbonic anhydrase

CO₂ absorption into aqueous solutions of two tertiary alkanolamines, namely, MDEA and DMEA with and without carbonic anhydrase (CA) was investigated with the use of the stopped‐flow technique at temperatures in the range of 293–313 K, CA concentration varying from 0 to 100 g/m³ in aqueous MDEA solution with the amine concentration ranging from 0.1 to 0.5 kmol/m³, and CA concentration varying from 0 to 40 g/m³ in aqueous DMEA solution with the amine concentration ranging from 0.05 to 0.25 kmol/m³. The results show that the pseudofirst‐order reaction rate (k_{0, amine}; s^?1) is significantly enhanced in the presence of CA as compared with that without CA. The enhanced values of the kinetic constant in the presence of CA has been calculated and a new kinetics model for reaction of CO₂ absorption into aqueous tertiary alkanolamine solutions catalyzed by CA has been established and used to make comparisons of experimental and calculated pseudo first‐order reaction rate constant (k_{0, with CA}) in CO₂‐MDEA‐H₂O and CO₂‐DMEA‐H₂O solutions. The AADs were 15.21 and 15.17%, respectively. The effect of pKa on the CA activities has also been studied by comparison of CA activities in different tertiary amine solutions, namely, TEA, MDEA, DMEA, and DEEA. The pKa trend for amines were: DEEA > DMEA > MDEA > TEA. In contrast, the catalyst enhancement in amines was in the order: TEA> MDEA> DMEA> DEEA. Therefore, it can be seen that the catalyst enhancement in the amines decreased with their increasing pKa values. © 2017 American Institute of Chemical Engineers AIChE J, 2017     

Poly ionic liquid cryogel of polyethyleneimine: Synthesis,characterization, and testing in absorption studies

Here, we report the synthesis of polyethyleneimine (PEI) cryogels for the first time via cryopolymerization technique. The crosslinking of amine groups on the branched PEI chains is accomplished with epoxy groups of glycerol diglycidyl ether (GDE) based on epoxy–amine reactions in excess water at ?18 °C in about 16 h. Superporous PEI cryogels with pore sizes >100 μm were shown to have very fast equilibrium swelling behavior, e.g., 10 s to reach maximum swelling in DI water. Furthermore, the synthesized PEI cryogels were exposed to anion exchange reaction after protonation by HCl treatments to generate PEI ionic liquid cryogels containing hexafluorophosphate, thiocyanate, dicyanamide, and tetrafluoroborate. It was also demonstrated that PEI cryogels modified with [PF₆]^? absorbed 47.8 ± 5.7 mg/g of bovine serum albumin (BSA). Moreover, PEI cryogels were shown to be very useful as simple filtration filling materials for the direct removal of organic dyes such as methyl orange (MO) and eosin Y (EY) from their corresponding aqueous solutions with 98.5 and 98.6% yields, respectively. The separation of methylene blue (MB) from MO and EY mixture by using PEI cryogels as column filler materials was also demonstrated. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43478.     

CO2 solubility in aqueous N-methylcyclohexylamine (MCA) and N-cyclohexyl-1,3-propanediamine (CHAP) solutions

N-methylcyclohexylamine (MCA) and N-cyclohexyl-1,3-propanediamine (CHAP) have been suggested, in mixtures with lipophilic amines, as potential phase change solvents for CO₂ capture applications, and subsequently studied as promising alternatives to monoethanolamine (MEA) for minimizing the desorber's energy requirements. In this study, new high pressure experimental data were obtained for the solubility of CO₂ in aqueous solutions containing MCA or CHAP at 313 and 333 K. The obtained data were used to parameterize the modified Kent–Eisenberg model. In this direction, CHAP was modeled assuming a “principle of independent reactivity,” that is, that the reactivity of each amine group does not depend on the potential reaction of the other one. It was shown that through this approach the model can be successfully applied to diamines using the relevant equations of amine mixtures.     

Diamine versus amines blend for CO2 chemical absorption

Present work analyses the behavior of aqueous solutions of N,N-dimethylethylenediamine as chemical solvent for carbon dioxide separation by gas–liquid absorption. The interest of this molecule is centered on the presence of different types of amino centers that confer it the capability to act as a solvent based on amines blend. For this reason, a comparison between diamine and amines blend solvent has been carried out in order to understand the differences between these solvents using absorption and nuclear magnetic resonance studies. This experimental work analyses the influence of amine type, concentration, and ratio between different amines. Also, the effect of gas flow rate used in the bubble column reactor upon the absorption kinetics has been analyzed.     

Simultaneous liquid–liquid and vapour–liquid equilibria predictions of selected oxygenated aromatic molecules in mixtures with alkanes,alcohols, water,using the polar GC-PC-SAFT

Phase equilibria of oxygen-bearing aromatic compounds, hydrocarbons and water mixtures are of essential interest in many processes using feeds originating from biomass. The strong non-ideal thermodynamic behavior of these systems sometimes results in immiscibility with both water and alkanes.To address this problem, the GC-PPC-SAFT equation of state [Tamouza et al., 2004; Nguyen-Huynh et al., 2008a] is extended to some selected components: phenol, alkyl-phenols, alkyl-benzoates, benzaldehyde and anisole. However, as in these multifunctional compounds, the proximity of polar functional groups may result in a lack of transferability of the parameters from the monofunctional homologous species, some parameters have been adapted in view of physical arguments. Next, liquid–vapour and liquid–liquid equilibria of mixtures with n-alkanes were evaluated, using a predictive method for the binary interaction parameters (k_ij) [Nguyen-Huynh et al., 2008b]. Finally, mixtures with other associating compounds, as alcohols and water have also been considered.In all cases, both correlations and predictions are qualitatively and quantitatively satisfactory. The relative deviations obtained on bubble pressure of vapor–liquid equilibria are 4–8%, that is comparable to those obtained on previously investigated systems.     

Simultaneous modeling of VLE,LLE and VLLE of CO2 and 1, 2, 3 and 4 alkanol containing mixtures using GC-PPC-SAFT EOS

A polar version of the group contribution PC-SAFT equation of state (GC-PPC-SAFT; Tamouza et al., 2004; NguyenHuynh et al., 2008) combined with a method for correlation/prediction of binary interaction parameters k_ij (NguyenHuynh et al., 2008) is here applied to model vapor–liquid, liquid–liquid and vapor–liquid–liquid phase equilibria of CO₂ + alkanol mixtures simultaneously.A cross-association interaction between CO₂ and alkanol had to be taken into account to model/predict the mixtures equilibria accurately. The cross-association parameters were evaluated using the so-called CR1 mixing rules supported by ab initio computations.Extensive prediction tests on CO₂ + alkanol mixtures involving linear and branched alkanols are carried out. The results obtained showed that in most cases, the correlation and prediction calculations are qualitatively and quantitatively satisfactory: the overall deviations on liquid phase and vapor phase are respectively ΔX = 3–4% and ΔY = 1–2%.     

CO2 capture by pyrrolidine: Reaction mechanism and mass transfer

A new carbon dioxide capture process by means of gas–liquid absorption using pyrrolidine aqueous solutions in a bubble column reactor obtaining suitable results in comparison with other commonly used amines is analyzed. The influence of several operation variables such as amine concentration and gas flow rate has been studied. Carbon dioxide mass‐transfer rate data have shown a different behavior than other amine‐based systems because a constant value in absorption rate was observed in the middle of batch experiments. ¹³C and ¹H NMR spectroscopy studies were performed to analyze the species present during the experiments. These data and the carbon dioxide loading allowed to explain the reaction mechanism existed between these reagents. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1098–1106, 2014     

The structure of aminofunctional silane coupling agents: 1. γ-Aminopropyltriethoxysilane and its analogues

Gamma-aminopropyltriethoxysilane (γ-APS) and its analogues are studied as aqueous solutions as well as solids by Fourier transform infra-red spectroscopy (FT i.r.) and laser Raman spectroscopy. Emphasis was placed on a determination of the nature of the interaction between the amine groups and the residual silanol groups in partially cured solids. Comparison with γ-aminopropyltrisilanolate and partially cured solids obtained from γ-aminopropylmethyldiethoxysilane and γ-aminopropyldimethylethoxysilane lead us to conclude that the residual silanol groups are strongly hydrogen bonded to the amine groups as SiOH … NH₂ rather than SiO^? … ⁺NH₃. Hydrolysis of γ-APS at concentrations ranging 2–80% by weight showed that the solutions below 40% by weight have a few unhydrolysed alkoxy groups. The amine groups are mutually hydrogen bonded in unhydrolysed silane. However, in an aqueous solution and highly cured solids, the amine groups are either free or are interacting predominantly with water molecules.     

Vapor-liquid equilibrium correlations for systems containing amines using a lattice fluid equation of state with hydrogen bonding

The nonrandom lattice equation of state with hydrogen bonding (NLF-HB EOS) was examined for the correlation of vapor-liquid equilibria (VLE) for binary amine and hydrocarbon mixture at various temperatures. For these mixtures, the consideration of hydrogen bondings in the lattice equation of state clearly improves the prediction for VLE. The amines were divided into four groups due to the different strength of the hydrogen bonding. For all groups, different hydrogen bonding parameters were obtained and evaluated. The effects of varying hydrogen bonding energies for NLF-HB EOS are discussed. For systems containing lower amines, the NLF-HB EOS showed excellent agreement with the experimental data. For the correlation of systems containing tertiary amine molecules, binary interaction parameter had to be involved instead of hydrogen bonding parameters.     

CO2‐Alkanolamine Reaction Kinetics: A Review of Recent Studies

Alkanolamines are the most popular absorbents used to remove CO₂ from process gas streams. Therefore, the CO₂ reaction with alkanolamines is of considerable importance. The aim of this article is to provide an overview on the kinetics of the reaction of CO₂ with aqueous solutions of alkanolamines. The various reaction mechanisms that are used to interpret experimental kinetic data – zwitterion, termolecular and base‐catalyzed hydration – are discussed in detail. Recently published data on reaction kinetics of individual amine systems and their mixtures are considered. In addition, the kinetic behavior of several novel amine‐based solvents that have been proposed in the literature is analyzed. Generally, the reaction of CO₂ with primary, secondary and sterically hindered amines is governed by the zwitterion mechanism, whereas the reaction with tertiary amines is described by the base‐catalyzed hydration of CO₂.     

A GC–MS study of the addition reaction of aryl amines with acrylic monomers

Previous studies have shown that the interaction of carboxylic acid groups with the amine functionalities of aryl amines, especially secondary and tertiary aryl amines, can lead to the free-radical polymerization of acrylic monomers such as methyl methacrylate. In this study, the Michael addition reaction of primary and secondary aryl amines with acrylic monomers such as acrylic acid (AA) was investigated. Equivalent amounts of either p-toluidine (PT) or N-phenylglycine (NPG) and AA were combined in polar solvents such as ethanol. The reactions were conducted at ambient (23°C) or near-ambient (37–60°C) temperatures. Samples (about 3–5 mg) of these products were then trimethylsilylated with a solution consisting of 0.4 mL of bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 0.4 mL of acetonitrile by heating for 30 min at 140°C under N₂. These derivatives were characterized by gas chromatography–mass spectrometry (GC–MS). The GC–MS analyses suggest that 1 mol of the primary amine PT had reacted with 2 mol of AA to yield the expected N-p-tolyliminodipropionic acid. Similarly, the secondary amine NPG added to 1 mol of AA yielded the corresponding mixed iminodiacid, N-phenyliminoacetic–propionic acid. It would appear that the Michael reaction of primary and secondary amines with acrylic monomers may offer a general, facile synthetic route to a variety of tertiary amines. Aryl amino acids of the type synthesized in this study may find use in a number of dental applications, e.g., as surface-active adhesive agents and as polymerization initiators or activators. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 67:1545–1551, 1998     

Determination of kinetics of CO2 absorption in solutions of 2‐amino‐2‐methyl‐1‐propanol using a microfluidic technique

The kinetics for the reactions of carbon dioxide with 2‐amine‐2‐methyl‐1‐propanol (AMP) and carbon dioxide (CO₂) in both aqueous and nonaqueous solutions were measured using a microfluidic method at a temperature range of 298–318 K. The mixtures of AMP‐water and AMP‐ethylene glycol were applied for the working systems. Gas‐liquid bubbly microflows were formed through a microsieve device and used to determine the reaction characteristics by online observation of the volume change of microbubbles at the initial flow stage. In this condition, a mathematical model according to zwitterion mechanism has been developed to predict the reaction kinetics. The predicted kinetics of CO₂ absorption in the AMP aqueous solution verified the reliability of the method by comparing with literatures’ results. Furthermore, the reaction rate parameters for the reaction of CO₂ with AMP in both solutions were determined. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4358–4366, 2015     

GOLD EXTRACTION FROM THIOSULFATE SOLUTIONS USING MIXED AMINES

ABSTRACT

The extraction of gold from thiosulfate solutions with amine oxide and its mixture with amines has been studied, the results show that the amine oxide (TRAO) has a higher extraction ability for gold compared with tertiary amine. It can extract gold from neutral and weakly alkaline thiosulfate solutions, similar to the primary amine as extractant. The addition of TRAO enhances the extent of gold extraction with primary, secondary, and tertiary alkyl amines, respectively. The stoichiometry for the extraction of gold from thiosulfate solutions using the mixed solvent containing the primary amine N₁₉₂₃ and the amine oxide TRAO was investigated using slope analysis. The compositions of the gold extraction species with mixed organic solvents are proposed.     

Extraction of Fatty Acids from Noncatalytically Cracked Triacylglycerides Using Aqueous Amines

It has been reported that a basic aqueous solution was effective in extracting short chain C₂–C₆ fatty acids from noncatalytically cracked triacylglyceride oils. However, the extraction efficiency was not optimal over the entire range (C₂–C₁₂) of acids present in the cracking reactor organic liquid product (OLP). Therefore, an additional study was performed to explore the efficiency of solvent extraction using aqueous amines for this application. Based on the screening of several amines, two tertiary amines, trimethyl amine (TMA), and dimethyl ethanolamine (DMEA), were selected and evaluated. The extraction conditions were optimized with respect to several factors: temperature, amine concentration, and the amine-to-OLPratio (amine/OLP). Under optimal conditions, both TMA and DMEA were effective in extracting a wide range of organic acids, with TMA removing 93% of total acids and DMEA removing 100% of total acids. The amine/OLP was found to be a significant factor, as was the concentration of the amine solution. Temperature was not found to be a significant factor over the range studied. These results provide a basis for the development of a scalable, continuous process to produce a variety of C₂–C₁₂ fatty acids from biological sources.     

Highly regioselective hydroaminomethylation of long chain alkenes catalyzed by Rh–BISBIS in a two-phase system

The hydroaminomethylation of long chain alkenes with secondary amines in aqueous/organic two-phase system catalyzed by rhodium catalyst precursor and water-soluble diphosphine ligand BISBIS (sulfonated 2,2′-bis(diphenylphosphinomethyl)-1,1′-biphenyl) was investigated. The result showed that the use of BISBIS improved the reaction activity and especially regioselectivity for linear amine significantly compared with the monophosphine ligand TPPTS [P(m-C₆H₄SO₃Na)₃], the ratio of linear to branched amine was up to 83.     

Reaction kinetics of 2‐((2‐aminoethyl) amino) ethanol in aqueous and non‐aqueous solutions using the stopped‐flow technique

Observed pseudo‐first‐order rate constants (k_o) for the reaction between CO₂ and 2‐((2‐aminoethyl) amino) ethanol (AEEA) were measured using the stopped‐flow technique in an aqueous system at 298, 303, 308 and 313 K, and in non‐aqueous systems of methanol and ethanol at 293, 298, 303 and 308 K. Alkanolamine concentrations ranged from 9.93 to 80.29 mol m^?3 for the aqueous system, 29.99–88.3 mol m^?3 for methanol and 44.17–99.28 mol m^?3 for ethanol. Experimentally obtained rate constants were correlated with two mechanisms. For both the aqueous‐ and non‐aqueous‐AEEA systems, the zwitterion mechanism with a fast deprotonation step correlated the data well as assessed by the reported statistical analysis. As expected, the reaction rate of CO₂ in the aqueous‐AEEA system was found to be much faster than in methanol or ethanol. Compared to other promising amines and diamines studied using the stopped‐flow apparatus, the pseudo‐first‐order reaction rate constants were found to obey the following order: PZ (cyclic‐diamine) > EDA (diamine) > AEEA (diamine) > 3‐AP (primary amine) > MEA (primary amine) > EEA (primary amine) > MO (cyclic‐amine). The reaction rate constant of CO₂ in aqueous‐AEEA was double that in aqueous‐MEA, and the difference increased with an increase in concentration. All reaction orders were practically unity. With a higher capacity for carbon dioxide and a higher reaction rate, AEEA could have been a good substitute to MEA if not for its high thermal degradation. AEEA kinetic behaviour is still of interest as a degradation product of MEA. © 2012 Canadian Society for Chemical Engineering     

Influence of chain length of tertiary amines on extractability and chemical interactions in reactive extraction of succinic acid

Reactive extraction of succinic acid from aqueous solutions with various tertiary amines dissolved in 1-octanol and in n-heptane has been studied as a function of the chain length of the tertiary amine. In the tertiary amine extractants in 1-octanol, the extractabilities of tertiary amines were proportional to their chain length. But, in n-heptane, the extractabilities of tertiary amines decreased with their chain length. In order to analyze chemical interactions involved in the complexation of succinic acid with amine extractants in 1-octanol and n-heptane, infrared (IR) spectroscopy was used. From IR spectroscopy, it was found that the difference of extractability in 1-octanol and in n-heptane was mainly due to the different degree of intramolecular hydrogen bonding of succinic acid with the polarity of diluents. And the possible stoichiometry of acid-amine-diluent complex was predicted as (1,1), (2,1), (1,1,1). Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University