Solubility Of CO2 In Mixtures Research Articles

Efficient hybrid modeling of CO2 absorption in aqueous solution of piperazine: Applications to energy and environment

Carbon dioxide (CO2) considerably contributes to the greenhouse effects and consequently, to the global warming. Thus, reduction of CO2 emissions/concentration in the atmosphere is an important goal for various industrial and environmental sectors. In this research work, we study CO2 capture by its absorption in mixtures of water and piperazine (PZ). Experimental techniques to obtain the equilibrium data are usually costly and time consuming. Thermodynamic modeling by Equations of State (EOSs) and connectionist tools leads to more reliable and accurate results, compared to the empirical models and analytical modeling strategies. This research work utilizes Genetic Programming (GP) and Genetic Algorithm-Adaptive Neuro Fuzzy Inference System (GA-ANFIS) to estimate the solubility of CO2 in mixtures of water and piperazine (PZ). In both methods, the input parameters are temperature, partial pressure of CO2, and concentration of PZ in the solution. A total number of 390 data points is collected from the literature and used to develop GP and GA-ANFIS models. Assessing the models by the statistical methods, both models are found to acceptably predict the CO2 solubility in water/PZ mixtures. However, the GP exhibits a superior performance, compared to GA-ANFIS; the values of Average Absolute Relative Error (AARD) are 5.3213% and 9.7143% for the GP and GA-ANFIS models, respectively. Such reliable predictive tools can assist engineers and researchers to effectively determine the key thermodynamic properties (e.g., solubility, vapor pressure, and compressibility factor) which are central to design and operation of the carbon capture processes in a variety of chemical plants such as power plants and refineries.

The Viscosity and Density of Ionic Liquid + Tetraglyme Mixtures and the Effect of Tetraglyme on CO2 Solubility

We show that the addition of tetraglyme (TG), which is a low viscosity liquid with relatively low vapor pressure, is effective in reducing the viscosity of ionic liquids (ILs). In particular, we measure the viscosities of mixtures of 18 ionic liquids with tetraglyme at temperatures between 278.15 and 323.15 K, with a focus on mixtures that are primarily ionic liquid. Thirteen of the ionic liquids contain aprotic heterocyclic anions (AHA ILs) paired with tetra-alkylphosphonium and imidazolium cations, which we have developed for cofluid vapor compression refrigeration and postcombustion CO2 capture applications. Three bis(trifluoromethylsulfonyl)amide ([Tf2N]−) ionic liquids are included for comparison, as well as trihexyltetradecylphosphonium acetate and trihexyltetradecylphosphonium dicyanamide ([P66614][acetate] and [P66614][DCA]). In addition, we present the densities of trihexyltetradecylphosphonium 1,2,3-triazolide ([P66614][3-Triz]) + tetraglyme mixtures at temperatures between 283.15 and 353.15 K. Finally, we show that the solubility of CO2 in mixtures of [P66614][3-Triz] + 30 mol % tetraglyme and trihexyltetradecylphosphonium 1,2,4-triazolide ([P66614][4-Triz]) + 30 mol % tetraglyme at 313.15, 333.5, and 353.6 K and pressures to 34 bar can be represented reasonably well by a mole fraction weighted sum of the solubilities (on a mole ratio basis) in the two pure components.

Effect of Additives on the CO2 Absorption in Aqueous MDEA Solutions

The use of antifoaming and corrosion inhibitor agents to prevent foaming and corrosion, respectively, is widely used in the carbon dioxide (CO2) absorption process using alkanolamines. However, the effect of these agents on the capacity of the alkanolamine solutions to absorb CO2 is unknown. We present a study on the phase equilibria and solubility of CO2 in mixtures of aqueous methyldiethanolamine (MDEA) solutions with and without these additives and show how the liquid phase properties and CO2 loading capacity is affected.

Physical Properties of 1-Butyl-3-methylimidazolium Tetrafluoroborate/N-Methyl-2-pyrrolidone Mixtures and the Solubility of CO2 in the System at Elevated Pressures

Densities and viscosities of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) (1) + N-methyl-2-pyrrolidone (NMP) (2) with w1 = 0.0000, 0.5000, 0.6999, 0.8981, and 1.0000 at T = (298.15 to 318.15) K were measured and fitted to standard equations. The results show that densities and viscosities of the hybrid solvents decrease with the increase of temperature and mass fraction of NMP. A high-pressure variable-volume view cell technique was used to determine the solubility of CO2 in pure solvents and mixtures under elevated pressures up to 6 MPa at temperatures from (298.15 to 318.15) K. The results indicate that the solubility of CO2 in the pure solvents and mixtures increases with the increase of pressure and with the decrease of temperature. The solubility of CO2 in the mixtures increases with the increase of the mass fraction of NMP, but it is very close to that in pure [bmim][BF4] as the mass fraction of NMP is around 0.1019.