Simultaneous absorption of carbon dioxide,sulfur dioxide,and nitrogen dioxide into aqueous 1, 8-diamino-p-menthane

3 gaseous mixtures of CO₂, SO₂, and NO₂ were simultaneously absorbed into 1, 8-diamino-p-menthane (DAM) in a stirred, semi-batch tank with a planar, gas-liquid interface within a range of 0–2.0 kmol/m³ of DAM, 0.05–0.3 atm of CO₂, 0.0025–0.04 atm of SO₂, and 298.15–323.15 K at a fixed NO₂ of 0.001 atm to measure their total molar fluxes. Diffusivity and Henry constants of CO₂, SO₂, and NO₂ were obtained using the reference data, measured by N₂O analogy. The mass transfer coefficient of each gas, needed to obtain the absorption rate without a chemical reaction, was modified with viscosity of aqueous DAM solution. In CO₂-SO₂-NO₂-DAM system accompanied by first-order reaction with respect to CO₂ and instantaneous reactions with respect to SO₂ and NO₂, the enhancement factors of CO₂ and SO₂ were obtained by using an approximate solution of mass balances consisting of reaction regimes of two gases, one of which reacts instantaneously, and then, the enhancement factor of NO₂ by comparing the instantaneous rates of SO₂ and NO₂. The observed values of the molar flux approached to the calculated values very well.     

Simultaneous Absorption of Carbon Dioxide and Sulfur Dioxide into Aqueous 1,8-Diamino-p-menthane

Abstract

Carbon dioxide and sulfur dioxide were simultaneously absorbed into aqueous 1,8-diamino-p-menthane (DAM) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–2.0 kmol/m³ of DAM, 0.01–0.12 mole fraction of CO₂, 0.001–0.012 mole fraction of SO₂, and 298-318 K. Absorption data of each gas in the CO₂-DAM and SO₂-DAM systems are obtained to verify their reaction regimes, based on film theory, respectively, which are used to analyze the simultaneous absorption mechanisms of CO₂ and SO₂ in the CO₂-SO₂- DAM systems. In the simultaneous absorption rate of CO₂ and SO₂ into DAM solution, the absorption of CO₂ belongs to the second-order reaction of finite rate and the absorption of SO₂ belongs to the instantaneous reaction regime.     

New AMP/polyamine blends for improved CO2 capture: Study of kinetic and equilibrium features

2-Amino-2-methyl-1-propanol (AMP), which is the sterically hindered form of monoethanolamine (MEA), is a credible substitute to conventional CO₂-capturing solvents. Its performance can be improved by blending with a highly reactive polyamine promoter. Two such aqueous blends of AMP/TETA and AMP/TEPA were chosen here (TETA = triethylenetetramine and TEPA = tetraethylenepentamine). The kinetics of CO₂ absorption in the proposed blends was investigated at 308, 313, and 318 K using the stirred cell technique. The concentrations of AMP and polyamine were varied between 2 to 3 kmol/m³ and 0.1 to 0.5 kmol/m³, respectively. From the measured values of the fast pseudo-first order constants, the second-order rate constants for the reactions of CO₂ with TETA (14 695 m³/(kmol s)) and TEPA (19 250 m³/(kmol s)) were determined at T = 313 K. Both TETA and TEPA react faster with CO₂ than MEA. Further, the respective activation energy values were found (40 and 37 kJ/mol). Finally, the equilibrium solubility of CO₂ for both blends was measured at T = 303 K. The loading capacity was higher than that for the aqueous blends of AMP/MEA, AMP/DEA, and AMP/MDEA (here, DEA and MDEA denote diethanolamine and N-methyldiethanolamine). The highest value of loading capacity (1.12 mol CO₂/mol amine at 2.01 kPa equilibrium partial pressure of CO₂) was noted in AMP/TEPA mixtures. The new findings on our proposed blends will strengthen the AMP/polyamine application in CO₂ separation.     

Simultaneous Absorption of Carbon Dioxide and Sulfur Dioxide into Aqueous 2-Amino-2-Methy-1-Propanol

Abstract

Carbon dioxide and sulfur dioxide were simultaneously absorbed into aqueous 2-amino-2-methyl-1-propanol (AMP) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–4.0 kmol/m³ of AMP, 0.03–0.3 mole fraction of CO₂, 0.005–2 mole fraction of SO₂, and 298–318 K. Absorption data of each gas in the CO₂-AMP and SO₂-AMP systems are obtained to verify their reaction regimes, based on film theory, respectively, which are used to analyze the simultaneous absorption mechanisms of CO₂ and SO₂ in the CO₂-SO₂-AMP systems. The measured absorption rates of CO₂ and SO₂ are compared to those formulated by an approximate solution of the mass balances with simultaneous reactions.     

Simultaneous Absorption of Carbon Dioxide and Nitrogen Dioxide into Aqueous 2-amino-2-methy-1-propanol

Carbon dioxide and nitrogen dioxide were simultaneously absorbed into aqueous 2-amino-2-methyl-1-propanol (AMP) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–4.0 kmol/m³ of AMP, 0.03–0.3 atm of CO₂, 0.005–0.2 atm of NO₂, and 298–318 K. Absorption data of each gas in the CO₂-AMP and NO₂-AMP systems were obtained to verify their reaction regimes, based on film theory, respectively, which were then used to analyze the simultaneous absorption mechanisms of CO₂ and NO₂ in the CO₂-NO₂-AMP systems. The measured absorption rates of CO₂ and NO₂ were compared to those formulated by an approximate solution of the mass balances with simultaneous reactions.     

The absorption rate of CO2/SO2/NO2 into a blended aqueous AMP/ammonia solution

The Inter-governmental Panel on Climate Change (IPCC) reported that human activities result in the production of greenhouse gases (CO₂, CH₄, N₂O and CFCs), which significantly contribute to global warming, one of the most serious environmental problems. Under these circumstances, most nations have shown a willingness to suffer economic burdens by signing the Kyoto Protocol, which took effect from February 2005. Therefore, an innovative technology for the simultaneously removal carbon dioxide (CO₂) and nitrogen dioxide (NO₂), which are discharged in great quantities from fossil fuel-fired power plants and incineration facilities, must be developed to reduce these economical burdens. In this study, a blend of AMP and NH₃ was used to achieve high absorption rates for CO₂, as suggested in several publications. The absorption rates of CO₂, SO₂ and NO₂ into aqueous AMP and blended AMP+NH₃ solutions were measured using a stirred-cell reactor at 293, 303 and 313 K. The reaction rate constants were determined from the measured absorption rates. The effect of adding NH₃ to enhance the absorption characteristics of AMP was also studied. The performance of the reactions was evaluated under various operating conditions. From the results, the reactions with SO₂ and NO₂ into aqueous AMP and AMP+NH₃ solutions were classified as instantaneous reactions. The absorption rates increased with increasing reaction temperature and NH₃ concentration. The reaction rates of 1, 3 and 5 wt% NH₃ blended with 30 wt% AMP solution with respect to CO₂/SO₂/NO₂ at 313 K were 6.05～8.49×10^?6, 7.16–10.41×10^?6 and 8.02～12.0×10^?6 kmol m^?2s^?1, respectively. These values were approximately 32.3–38.7% higher than with aqueous AMP solution alone. The rate of the simultaneous absorption of CO₂/SO₂/NO₂ into aqueous AMP+NH₃ solution was 3.83–4.87×10^?6 kmol m^?2s^?1 at 15 kPa, which was an increase of 15.0–16.9% compared to 30 wt% AMP solution alone. This may have been caused by the NH₃ solution acting as an alternative for CO₂/SO₂/NO₂ controls from flue gas due to its high absorption capacity and fast absorption rate.     

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     

A Study on CO2 Absorption Kinetics by Aqueous Solutions of N,N‐Diethylethanolamine and N‐Ethylethanolamine

N‐Ethylethanolamine (EEA) and N,N‐diethylethanolamine (DEEA) represent promising candidate alkanolamines for CO₂ removal from gaseous streams, as they can be prepared from renewable resources. In this work, the reaction rate constant for the reaction between CO₂ and EEA was determined from the absorption rate measurements of CO₂ in a blend comprising DEEA, EEA and H₂O. A stirred‐cell reactor with a plane, horizontal gas‐liquid interface was used for the absorption studies. While the DEEA concentration in the formulated solution was varied in the range of 1.5–2.5 kmol/m³, the initial EEA concentration was 0.1 kmol/m³. A zwitterion mechanism for EEA and a base‐catalyzed hydration mechanism for DEEA were used to describe the reaction kinetics. At 303 K, the second‐order reaction rate constant for the CO₂ reaction with EEA was found to be 8041 m³/(kmol s). The liquid‐side mass transfer coefficient was also estimated, and its value (0.004 cm/s) is in line with those typical of stirred‐cell reactors.     

Simultaneous absorption of CO<Subscript>2</Subscript> and SO<Subscript>2</Subscript> into aqueous AMP/NH<Subscript>3</Subscript> solutions in binary composite absorption system

To enhance the absorption rate for CO₂ and SO₂, aqueous ammonia (NH₃) solution was added to an aqueous 2-amino-2-methyl-1-propanol (AMP) solution. The simultaneous absorption rates of AMP and a blend of AMP+ NH₃ for CO₂ and SO₂ were measured by using a stirred-cell reactor at 303 K. The process operating parameters of interest in this study were the solvent and concentration, and the partial pressures of CO₂ and SO₂. As a result, the addition of NH₃ solution into aqueous AMP solution increased the reaction rate constants of CO₂ and SO₂ by 144 and 109%, respectively, compared to that of AMP solution alone. The simultaneous absorption rate of CO₂/SO₂ on the addition of 1 wt% NH₃ into 10 wt% AMP at a p _A1 of 15 kPa and p _A2 of 1 kPa was 5.50×10⁻⁶ kmol m⁻² s⁻¹, with an increase of 15.5% compared to 10 wt% AMP alone. Consequently, the addition of NH₃ solution into an aqueous AMP solution would be expected to be an excellent absorbent for the simultaneous removal of CO₂/SO₂ from the composition of flue gas emitted from thermoelectric power plants.     

Simultaneous absorption of carbon dioxide,sulfur dioxide and nitrogen dioxide into aqueous 2-amino-2-methy-1-propanol

The absorption mechanism of three acidic gases in alkali solution, such as the system of carbon dioxide, sulfur dioxide, and nitrogen dioxide in 2-amino-2-methyl-1-propanol (AMP), was used to predict the simultaneous absorption rates using the film theory. Diffusivity, Henry constant and mass transfer coefficient of each gas were used to obtain the theoretical enhancement factor of each component. The theoretical molar fluxe of each gas was obtained by an approximate solution of mass balances with reaction regions of the first order reaction of CO₂ and instantaneous reactions of SO₂ and NO₂ in CO₂-SO₂-NO₂-AMP system. From the comparison between the theoretical total fluxes of these gases and the measured ones, the solubility and the reaction rate between each gas and AMP influenced its molar flux.     

Absorption of Carbon Dioxide into Ionic Liquid of 2-Hydroxy Ethylammonium Lactate

Abstract

Absorption of carbon dioxide into organic solvents such as DMA, NMP, DMSO, and DMF with the 2-hydroxy ethylammonium lactate (HEAL) ionic liquid was investigated using a batch stirred tank with a plane of gas-liquid interface in a range of 0–2.0 kmol/m³ of HEAL and 298–318 K at 101.3 kPa. The absorption of CO₂ was analyzed with the film model accompanied by the zwitterion mechanism of CO₂ with HEAL. The proposed model fits the experimental data of the enhancement factor due to the ready, chemical absorption of CO₂ in different solvents, temperatures, and HEAL concentrations. The reaction rate constant of CO₂ with HEAL was correlated linearly with the solubility parameter of the solvent.     

The solubility of H2S and CO2 in a diethanolamine solution at low partial pressures

The solubility of H₂S, CO₂ and their mixtures in a 2.0 kmol m^?3 aqueous solution of diethanolamine has been determined at 40°C and 100°C at partial pressures of the acid gases between 0.003 and 6.5 kPa. The results have been compared with values calculated by a method of prediction.     

Absorption of carbon dioxide into aqueous colloidal silica solution with different sizes of silica particles containing monoethanolamine

Carbon dioxide was absorbed into an aqueous nanometer-sized colloidal silica solution in a flat-stirred vessel at 25 °C and 101.3 kPa to measure the absorption rate of CO₂. The concentrations of silica were in the range of 0–31 wt% and the sizes were 7, 60, and 111 nm. The solution contained monoethanolamine (MEA) of 0–2.0 kmol/m³. The volumetric liquid-side mass transfer coefficient (k _L a) of CO₂ was correlated with the empirical formula representing the rheological property of silica solution. The use of the aqueous colloidal silica solution resulted in a reduction of the absorption rate of CO₂ compared with Newtonian liquid based on the same viscosity of the solution. The chemical absorption rate of CO₂ was estimated by film theory using k _L a and physicochemical properties of CO₂ and MEA.     

Absorption of carbon dioxide in aqueous colloidal silica solution with NaOH

The absorption rate (R _A ) of carbon dioxide was measured into an aqueous nanometer-sized colloidal silica solution of 0–31 wt% and NaOH of 0–2 kmol/m³ in a flat-stirred vessel for various sizes and speeds of 25 °C and 101.3 N/m² to obtain the volumetric liquid-side mass transfer coefficient (k _L a _L ) of CO₂. The film theory accompanied by chemical reaction between CO₂ and NaOH was used to estimate the theoretical value of absorption rate of CO₂. The empirical correlation formula containing the relationship between k _L a _L and rheological property of the aqueous colloidal silica solution was presented. The value of R _A in the aqueous colloidal silica solution was decreased by the reduction of k _L a _L due to elasticity of the solution.     

Absorption of Carbon Dioxide into Aqueous Xanthan Gum Solution Containing Monoethanolamine

Abstract

Carbon dioxide was absorbed into the aqueous xanthan gum (XG) solution in the range of 0–0.151 wt% containing monoethanolamine (MEA) of 0–2 kmol/m³ in a flat‐stirred vessel with the impeller of 0.05 m and agitation speed of 50 rpm at 25°C and 0.101 MPa to measure the absorption rate of CO₂. The volumetric liquid‐side mass transfer coefficient (k_La_L) of CO₂ decreased with increasing XG concentration, and was correlated with the empirical formula having the rheological behavior of XG solution. The chemical absorption rate of CO₂ was estimated by the film theory using the values of k_La_L and physicochemical properties of CO₂ and MEA. The aqueous XG solutions made the rate of absorption of CO₂ accelerated compared with the Newtonian liquid based on the same viscosity of the solution.     

The solubility of carbon dioxide and hydrogen sulfide in a 35 wt% aqueous solution of methyldiethanolamine

The solubility of hydrogen sulfide and carbon dioxide in an aqueous solution containing 35 wt% methyldiethanolamine (MDEA) (3.04 kmol/m³, 4.52 mol/kg) has been measured at 40° and 100°C at partial pressures of the acid gas up to 530 kPa. Some data for hydrogen sulfide in a 50 wt% solution of MDEA (4.38 kmol/m³, 8.39 mol/kg) were also obtained. Also, densities of CO₂-aqueous MDEA solutions were measured at 40°C.     

Absorption of carbon dioxide into aqueous solutions of piperazine activated 2-amino-2-methyl-1-propanol

In this work, new experimental data on the rate of absorption of CO₂ into piperazine (PZ) activated aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) are reported. The absorption experiments using a wetted wall contactor have been carried out over the temperature range of 298-313 K and CO₂ partial pressure range of 2-14 kPa. PZ is used as a rate activator with a concentration ranging from 2 to 8 wt%, keeping the total amine concentration in the solution at 30 wt%. The CO₂ absorption into the aqueous amine solutions is described by a combined mass transfer-reaction kinetics-equilibrium model, developed according to Higbie's penetration theory. Parametric sensitivity analysis is done to determine the effects of possible errors in the model parameters on the accuracy of the calculated CO₂ absorption rates from the model. The model predictions have been found to be in good agreement with the experimental results of rates of absorption of CO₂ into aqueous (PZ+AMP). The good agreement between the model predicted rates and enhancement factors and the experimental results indicates that the combined mass transfer-reaction kinetics-equilibrium model with the appropriate use of model parameters can effectively represent CO₂ mass transfer in PZ activated aqueous AMP solutions.     

Absorption of carbon dioxide in alkanolamines in the presence of fine activated carbon particles

The rates of absorption of CO₂ into water and 0.1 kmol/m³ aqueous solutions of MEA, DEA and AMP were measured in a stirred cell with a flat gas-liquid interface in the presence of fine activated carbon particles. Experiments showed that the rates of absorption increased significantly with increases in the loading of activated carbon up to about 6 kg/m³ and thereafter remained constant.     

Chemical Absorption of Carbon Dioxide into Aqueous Colloidal Silica Solution with Diethanolamine

Abstract

The chemical absorption rate (R_A) of CO₂ was measured into the aqueous nanometer sized colloidal silica solution of 0–31 wt% and diethanoleamine of 0–2 kmol/m³ in the flat‐stirred vessel with the impeller size of 0.034 m and its agitation speed of 50 rev/min at 25°C and 0.101 MPa, and compared with the values estimated from the model based on the film theory accompanied by chemical reaction. The value of the volumetric liquid‐side mass transfer coefficient (k_La) of CO₂, which was used to estimate the value of R_A, was obtained by the empirical correlation formula presenting the relationship between k_La and the rheological behavior of the aqueous colloidal silica solution. The value of R_A in the aqueous colloidal silica solution was decreased by the reduction of k_La due to the elasticity of the solution.     

The solubility of mixtures of carbon dioxide and hydrogen sulphide in an aqueous dipa solution

The solubility of mixtures of carbon dioxide and hydrogen sulphide in an aqueous solution of di-isopropanolamine (2.5 kmol m^?3 DIPA) has been measured at temperatures of 40 °C and 100°C. Partial pressures of CO₂ ranged from 2.0 to 5991 kPa, while partial pressures of H₂S ranged from 1.3 to 4126 kPa.