Absorption of carbon dioxide into aqueous monoethanolamine solutions

The rates of absorption of pure carbon dioxide into aqueous diethanolamine solutions were measured at 25°C in a liquid-jet column and a wetted-wall column. Experimental results were analyzed with the chemical absorption theory based on the penetration model. Physical solubility of carbon dioxide in aqueous diethanolamine solutions was determined from the absorption rates measured in a near pseudo first-order reaction regime and was found to show a salting-out effect. The measured absorption rates were in good agreement with the theoretical predictions for gas absorption with an irreversible third-order reaction.

Absorption of carbon dioxide into aqueous sodium hydroxide and sodium carbonate-bicarbonate solutions

In this work, the absorption of pure carbon dioxide by aqueous triethanolamine solutions (TEA) was studied in terms of the kinetic process. The process was made in a stirred tank reactor with a flat and known interfacial area, the operating variables being temperature (288 to 313 K) and concentration in the range 0.1-2.0 M. From the results, it was deduced that the absorption of pure carbon dioxide by aqueous triethanolamine takes place under isothermal conditions in which there is an instantaneous reaction regime at low concentrations, while at higher concentrations it takes place in a moderately fast reaction regime, following a first-order kinetic with respect to alkanolamine. In these conditions of concentrations and temperatures essayed, an expression for the constant kinetic was deduced.

Carbon dioxide absorption in a cross-flow rotating packed bed

The rates of absorption of pure carbon dioxide into aqueous sodium sulfite solutions containing or not containing sodium sulfate were measured at 15, 25, 35 and 45°C and at atmospheric pressure using a liquid‐jet column, a wetted‐wall column, and a quiescent‐liquid absorber. The experimental results were analyzed by the chemical absorption theory based on the penetration model. The second‐order forward rate constants for the reaction between carbon dioxide and sulfite ion in aqueous solutions were calculated and correlated as a function of temperature and ionic strength of the solution. The chemical equilibrium constants for the reaction were also determined from the measurements of the total solubility of carbon dioxide in aqueous sodium sulfite solutions.

The process of absorption of pure carbon dioxide by individual drops of water has been studied. It has been shown that, contrary to the assumption of previous workers, the rate of gas absorption of a drop during the period of formation may be very high, especially when the time of formation is short. This is due to the turbulence produced within the drop by the injection of the supply jet, which reduces the resistance to diffusion at the surface of the drop. The absorption coefficient of drops during formation has been shown to be inversely proportional to a function of the time of formation, and directly proportional to the ‘degree of turbulence,’ a concept which can be expressed in terms of orifice dimensions. The influence of the ‘degree of turbulence’ on the magnitude of the overall absorption coeficients used in chemical engineering computations is discussed.

Absorption of carbon dioxide in O/W emulsion absorbent: Kinetics of absorption in N-methylcyclohexylamine and 2,6-dimethylpiperidine emulsion

To confirm the theory for gas absorption accompanied by an instantaneous irreversible reaction in laminar falling films of power‐law liquids which was presented in a previous paper, experiments were carried out on the absorption of pure carbon dioxide into aqueous kaolin slurries containing sodium hydroxide by using a long wetted‐wall column. The experimental data were in fairly good agreement with the theoretical predictions, the average deviation being 3.0%. The discussion on the effect of the power‐law index of the liquid upon the reaction factor suggested an approximate method of estimating the reaction factors for power‐law liquids.

Absorption characteristics of carbon dioxide into an O/W emulsion absorbent containing N-methylcyclohexylamine/2,6-dimethylpiperidine

Alkyl amines, which have multiple amino groups, are used as activators to improve the CO2 absorption performances of aqueous methyldiethanolamine (MDEA) solutions. The aqueous MDEA blends consisted of 20% (w/w) of MDEA and 10% (w/w) of activators, which are 3-methylamino propylamine (MAPA), diethylenetriamine (DETA), triethylene tetramine (TETA), and tetraethylenepentamine (TEPA). Aqueous solutions of monoethanolamine (MEA; 30% (w/w)) and MDEA (30% (w/w)) are used as reference absorbents for comparison. The CO2 absorption performances of aqueous MDEA blends were investigated by measurements of absorption capacities, absorption rates, and heats of absorption. The MDEA blends have higher CO2 absorption capacities than MEA and MDEA. MDEA/TEPA shows the highest CO2 loading amount of 0.753 mol-CO2·mol-absorbent–1 at 313 K. In addition, the MDEA blends show high cyclic capacities (0.241–0.330 mol-CO2·mol-absorbent–1), the values of which are about 3 times higher than that of MEA. All MDEA blends show higher absorption fluxes than MDEA. The MDEA/MAPA showed the highest overall mass transfer coefficient of 3.351 × 103 mol·m–2·s–1·kPa–1, 8 times higher than that of MDEA (0.451 × 103 mol·m–2·s–1·kPa–1) and even higher than that of MEA (3.014 × 103 mol·m–2·s–1·kPa–1). The heats of absorption of the MDEA blends (57.21–59.53 kJ·mol-CO2–1) are about 30% higher than that of MDEA and about 30% lower than that of MEA.

Marangoni instability during the absorption of carbon dioxide into aqueous solutions of monoethanolamine

Absorption of carbon dioxide in aqueous ammonia

ABSTRACTEnvironmental concerns from global warming and climate change demand carbon dioxide separation from post-combustion gases. Important parameters are involved in choosing the suitable solvent for carbon dioxide separation, including the reaction rate of carbon dioxide and the solvent. In this paper, the kinetics of carbon dioxide (CO2) absorption in aqueous solutions of Monoethanolamine (MEA) + 1,3-Diaminopropane (DAP), a diamine containing two primary amino group, was developed. The measurements were performed in a stirred cell with a horizontal gas-liquid interface in the temperature range of 313.15–333.15 K and aqueous solutions of 10 wt% MEA + 5 wt% DAP and 12.5 wt% MEA + 2.5 wt% DAP. Experiments were conducted in an isothermal batch reactor with a horizontal gas-liquid interface under pseudo-first-order conditions, enabling the determination of the overall kinetic rate constant from the pressure drop method. Second-order reaction rate constants of CO2 absorption in amine solutions were estimated using the calculated initial absorption rate. It was found that the rate constants in MEA+ DAP solutions were greater than in MEA solutions which means that DAP increases the reaction rate.

Chemical absorption into concentrated slurry: Absorptions of carbon dioxide and sulfur dioxide into aqueous concentrated slurries of calcium hydroxide

Absorption of carbon dioxide into aqueous solutions of ethylenediamine: Effect of interfacial turbulence