Carbon Dioxide Chemical Absorption Research Articles

Carbon Dioxide Removal Using Blended Amine Solution in a Randomly Packed Bed Column

Many researchers are currently investigating carbon dioxide capture and storage since it is suppressing the global warming phenomenon. Aqueous carbon dioxide chemical absorption is the most effective method. The present study incorporates the applicability and performance of blended alkanol amine solutions monoethanolamine (MEA) with diethylenetriamine (DETA) as a chemical blended absorbent investigated in a pilot scale column packed randomly with Rashing rings. The effect of operating conditions on absorption performance was examined. The performance investigation is given in terms of the overall mass transfer coefficient and carbon dioxide capture efficiency (ƞ). Typically, DETA: MEA with a mass ratio of 1:1 and total mass concentration of 30 % wt. could provide the highest KGav with a value of 0.1572 (kmol/(m3*Kpa*hr)) and ƞ with a value of 98.79 %. While at the same condition in terms of liquid and gas rate, with DETA: MEA in the blending mass ratio 0.25:1, the KGav and ƞ values equal to: 0.1198 (kmol/(m3*Kpa*hr)) and 96.37%, respectively. Based on these findings, it is reasonable to assume that diethylenetriamine, a solution of alkanol amines, would serve as an efficient blending absorbent for carbon dioxide removal.

Integrated capture and solar-driven utilization of CO2 from flue gas and air

Integrated capture and solar-driven utilization of CO2 from flue gas and air

Carbon Dioxide Chemical Absorption Using Diamines with Different Types of Active Centers

The present research analyzes chemical solvents based on the use of diamines (Ethylenediamine-EDA, 1,2-Dimethylethylenediamine-DMEDA and Tetramethylethylenediamine-TMEDA) for carbon dioxide absorption, taking into account the type of amino centers in the molecules. The presence and type of radicals can affect amine solubility in water, reaction mechanism, reaction kinetics, etc. Diamines have been considered interesting candidates for carbon dioxide chemical absorption, observing a high influence of the molecule structure. The present work analyzes a series of solvents based on diamines with the same chain length between amino centers, but different types of radicals. This study shows an important variability in the behavior of these solvents. EDA-based solvents have shown high absorption rates and stability, but carbamate hydrolysis is relatively low, avoiding an increase in carbon dioxide loading.

CO2 chemical absorption into AMP aqueous solution and mass transfer intensification in cascade sudden expansion microchannels

Carbon dioxide chemical absorption into 2-amino-2-methyl-1-propanol (AMP) aqueous solution and mass transfer enhancement in cascade sudden expansion microchannels were investigated by a high-speed digital camera. The influences of the flow rates of gas and liquid phases, the sudden expansion units and the concentration of AMP on the gas-liquid two-phase flow and mass transfer performance are studied systematically. Results showed that the increase of sudden expansion unit is conductive to increase liquid side volumetric mass transfer coefficient and enhancement factor. The maximal enhancement factor could reach to 1.33, and the maximally effective mass transfer efficiency could reach 1.6 under taking the energy consumption into account. The gas phase flow rate has slight effect on mass transfer enhancement factor E, while E decreases with increasing liquid phase flow rate. With the increase of AMP concentration, the volumetric mass transfer coefficient increases, but the enhancement factor decreases. A new correlation with good prediction performance was proposed for the volumetric mass transfer coefficient. Furthermore, the energy consumption and effective mass transfer efficiency were assessed.

Kinetics, absorption and regeneration of biphasic solvent with ethylpiperidine for carbon dioxide absorption

The development of new solvents for carbon dioxide separation by chemical absorption has increased its importance during last years. Present work develops a series of studies using biphasic solvents (two liquid phases) in which amine is transferred from organic to aqueous phase during carbon dioxide chemical absorption. This type of solvents gets to reduce the amount of solvent that must be regenerated by stripping and this fact allows to reduce significantly the cost associated to this operation. The experimental results corresponding to the proposed solvent (based on the use of N-ethylpiperidine) have shown a suitable behavior when high ratios of organic phase/aqueous phase are used that allows to reduce the energy penalty. This behavior has been confirmed using bubbling and packed columns. Solvent regeneration studies showed suitable results avoiding losses in absorption rate and absorption capacity.

Carbon dioxide chemical absorption in non-aqueous solvents by the presence of water

Abstract Present work analyzes the role of water in a gas–liquid–liquid absorber using a non-soluble amine (octylamine) in water. The presence of water causes an enhancement in carbon dioxide loading and absorption rate in comparison with the use of the organic solvent. Several issues have been analyzed in present research work: influence of gas flow-rate, water and amine concentration, type of organic solvent and solvent regeneration. The analysis of experimental data and speciation studies by using nuclear magnetic resonance allows to understand the overall behavior with the accumulation of reaction products in the organic phase by the formation of water-in-oil microemulsion. The accumulation of reaction products allows to decrease the solvent flow rate that must be regenerated and it can decrease the cost of this type of operation.

Influence of organic co-solvents upon carbon dioxide chemical absorption

Present research work analyzes carbon dioxide chemical absorption using different types of alkanolamines (primary, secondary and tertiary) with the presence of several organic co-solvents. These additional substances have been considered as interesting additives in previous works that can produce improvements upon the overall carbon dioxide separation process. On the basis of this hypothesis, this research analyses the influence of these solvents upon the absorption process using two parameters: absorption rate and carbon dioxide loading. Two different types of co-solvents have been tested analyzing the effect of their concentration in the liquid phase. Also the influence of these substances upon the reaction mechanism has been studied.

CO2 absorption with tri-n-butylamine in GL and GLL systems

Present research work is focused on the analysis of carbon dioxide chemical absorption with tri-n-butylamine (TBA) due to the suitable behavior previously shown by some tertiary amines (mainly methyldiethanolamine). TBA has a negative characteristic due to its low solubility in water that implies the use of an organic co-solvent using several alcohols in present work. Ethanol showed the best experimental results in carbon dioxide absorption rate and loading. A decrease in carbon dioxide loading in comparison with tertiary amines in aqueous solution was observed due to the high chemical interactions between water and ethanol molecules. It was confirmed using monoethanolamine + water + ethanol as chemical solvent and its comparison with the liquid phase in the absence of ethanol. A very important issue for TBA-solvent is the dramatic decrease in solvent degradation under stripping experimental conditions. This fact reduces until a minimum the solvent make-up flow-rate with a very important decrease in the overall process cost.

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

Process analysis for the carbon dioxide chemical absorption–regeneration system

The process analysis for the post-combustion CO2 capture using amine-based solvents is nowadays a fundamental step in its industrial scale design. In this work, the absorption-solvent regeneration system is deeply analyzed for different values of the loading in the solvent entering the absorber. The importance of the temperature and composition column profiles is highlighted for both the columns. In particular, the tight connection between the profiles and the L/G ratio is found to influence the choice of solvent flow rate for what concerns the absorber. On the other hand, an alternative configuration for the stripper is proposed together with a new criterion for the evaluation of the packing height. Finally, it is found that, in order to minimize the energy consumption in the stripper, the rich solvent must be sent at the highest possible temperature, taking into account the limitations imposed by the minimum temperature approach in the cross heat-exchanger and the solvent degradation.

CO2 Absorption and Regeneration Using Amines with Different Degrees of Steric Hindrance

AbstractThe influence of steric hindrance in amines upon different characteristics in carbon dioxide chemical absorption, namely, absorption rate, carbon dioxide loading, and regeneration degree, has been analyzed. Aqueous solutions of monoethanolamine, 1‐amino‐2‐propanol, and 2‐amino‐2‐methyl‐1‐propanol were used to compare their behavior during carbon dioxide absorption. The presence of one or two methyl groups on the carbon next to the amino group produced changes in the analyzed parameters. In addition, the influences of the gas‐flow rate and amine concentration on the chemical solvent behavior were studied to improve the mass transfer under different experimental conditions.

Carbon dioxide capture with tertiary amines. Absorption rate and reaction mechanism

Present work analyzes the overall carbon dioxide chemical absorption process using tertiary amines in aqueous solution, taking into account absorption rate experimental data and 13C and 1H nuclear magnetic resonance. These studies try to detect the causes because different behaviors are obtained for absorption curves at different carbon dioxide loadings. The combined use of these techniques allows to evaluate the weight of different variables (chemical kinetics, mechanism, hydrodynamics, etc) upon the absorption overall process.

Carbon dioxide chemical absorption using methylpiperidines aqueous solutions

Present research work has centered on the improvement of carbon dioxide chemical absorption with piperidine aqueous solutions changing the solvent to reach better solvent characteristics and avoid certain negative items such as high toxicity and corrosion. This aim will be obtained by using solvents with an additional methyl group in the molecule in different parts of piperidine, and analyzing the effect upon carbon dioxide absorption behavior. The carbon dioxide absorption rate has been analyzed under different operation conditions (gas flow-rate and amine concentration) and type of solvent using a semicontinuous gas-liquid contactor (batch for liquid phase and continuous for gas phase). Also carbon dioxide loading was determined for each solvent in relation with reaction mechanism between carbon dioxide and each amine. The regeneration process was carried out for the best solvent using a treatment with calcium hydroxide avoiding the high temperatures in stripping methodology reaching better results that the best available technique.

Mechanisms of low temperature capture and regeneration of CO2 using diamino protic ionic liquids.

Carbon dioxide (CO2) chemical absorption and regeneration was investigated in two diamino carboxylate protic ionic liquids (PILs), dimethylethylenediamine formate (DMEDAH formate) and dimethylpropylenediamine acetate (DMPDAH acetate), using novel calorimetric techniques. The PILs under study have previously been shown to possess a CO2 absorption capacity similar to the industrial standard, 30% aqueous MEA, while requiring much lower temperatures to release the captured CO2. We show that this is in part due to the fact that the PILs exhibit enthalpies of CO2 desorption as low as 40 kJ mol(-1), significantly lower than the 85 kJ mol(-1) required for 30% aqueous MEA. Computational and spectroscopic analyses were used to probe the mechanism of CO2 capture, which was found to proceed via the formation of carbamate moieties on the primary amine of both DMEDAH and DMPDAH. Evidence was also found that weakly acidic counter-ions such as formate and acetate provide, unexpectedly, an additional proton acceptor site in the traditional carbamate mechanism, revealing opportunities to increase CO2 uptake capacity in the future through careful design of the anion and cation used in the PIL capture agent.

Density, Speed of Sound, Viscosity, and Surface Tension of Dimethylethylenediamine + Water and (Ethanolamine + Dimethylethanolamine) + Water from T = (293.15 to 323.15) K

This work analyzes different physical properties with importance upon mass transfer processes (density, speed of sound, viscosity, and surface tension) for new chemical solvents for carbon dioxide capture (dimethylethylenediamine + water and ethanolamine + dimethylethanolamine + water). These solvents are composed of two different amino groups: a primary and a tertiary. In one solvent, it is achieved by the use of a diamine and for the other a mixture of two solutes is employed. Also excess properties have been studied in order to explain the behavior of previously commented properties on the basis of interactions between molecules. An increase in the amount of amine or amines in the mixtures generally causes a decrease in the analyzed properties but in speed of sound and viscosity a previous increase was observed. An increase in temperature also causes a decrease in all the physical properties. Also the diamine-based solvent shows higher molecular interactions than the amine mixture. These data allow one to perform a comparison between the properties of these solvents that can be useful information to choose one of them. On the basis of these properties, this kind of solvent (diamine + water) is better to be used in carbon dioxide chemical absorption

Screening and Characterization of Advanced Amine Based Solvent Systems for CO2 Post-Combustion Capture

Carbon dioxide chemical absorption with amine based solvents is currently the state-of-the-art technology for post-combustion carbon capture. However, many technical challenges still remain that need to be addressed to make it cost-effective. Through bench-scale tests, this research work is focused on developing and characterizing advanced amine-based solvents. Screening of amine solvents is performed to identify suitability on the basis of solvent maximum concentration, rich CO2 loading, lean CO2 loading, cyclic CO2 loading and energy requirement. The five alkanolamine solvents which are experimented upon in this work are: monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), Piperazine (PZ) and 2-Amino-2-methyl-1-propanol (AMP). These solvents are taken as reference solvents to allow comparison with literature data and to establish confidence in the experimental methods used for solvent evaluation. CO2 outlet concentration curves from the absorption experiments show that piperazine reaches equilibrium faster than any other solvent and the CO2 loading capacity from phosphoric acid titration method is highest in piperazine with a value of 0.92.

Kinetics of carbon dioxide chemical absorption into cyclic amines solutions

AbstractChemical reaction kinetics between carbon dioxide with two cyclic amines (pyrrolidine and piperidine) have been studied using a stirred tank reactor with a planar interfacial area. The operational variables considered in this work have been the amine concentration in the liquid phase and the reaction temperature. Specific absorption rates have been determined under different experimental conditions. Results indicate that the absorption process occurs in a pseudo first reaction regime exhibited first‐order kinetic with respect carbon dioxide and a second order for both cyclic amines. The reaction‐rate constant was determined under the different experimental conditions, and it was correlated depending on the temperature by means of an Arrhenius type equation. © 2010 American Institute of Chemical Engineers AIChE J, 2011