Investigation of CO2 solubility in monoethanolamine hydrochloride based deep eutectic solvents and physical properties measurements

Deep eutectic solvents(DESs)have drawn a growing research interest for applications in a wide range of scientific and industrial arenas.However,a limited effort has been reported in the area of gas separation processes and particularly the carbon dioxide capture.This study introduces a novel set of DESs that were prepared by complexing ethylenediamine(EDA),monoethanolamine(MEA),tetraethylenepentamine(TEPA),triethylenetetramine(TETA)and diethylenetriamine(DETA)as hydrogen bond donors to monoethanolamide hydrochloride(EAHC)salt as a hydrogen bond acceptor.The absorption capacity of CO2 was evaluated by exploiting a method based on measuring the pressure drop during the absorption process.The solubility of different DESs was studied at a temperature of 313.15 K and initial pressure of 0.8 MPa.The DES systems 1 EAHC:9 DETA,1 EAHC:9 TETA and 1 EAHC:9 TEPA achieved the highest CO2 solubility of 0.6611,0.6572 and 0.7017 mol CO2·(mole DES)-1 respectively.The results showed that CO2 solubility in the DESs increased with increasing the molar ratio of hydrogen bond donor.In addition,the CO2 solubility increased as the number of amine groups in the solvent increases,therefore,increasing the alkyl chain length in the DESs,resulted in increasing the CO2 solubility.FTIR analysis confirms the DES synthesis since no new functional group was identified.The FTIR spectra also revealed the carbamate formation in DES-CO2 mixtures.In addition,the densities and viscosities of the synthesized DESs were also measured.The CO2 initial investigation of reported DESs shows that these can be potential alternative for conventional solvents in CO2 capture processes.

Experimental and modelling study of the solubility of CO_2 in various CaCl_2 solutions at different temperatures and pressures

Study of the thermodynamic behaviour of CaCl2-H2O-CO2 systems is important in different scientific areas in the chemical and petroleum engineering fields. For example, a system including salt- H20-CO2 is a common system in CO2 geological storage. During carbonate matrix acidizing, this mixture also appears as the spent acid. Hence, study of the behaviour of this system and the solubility of CO2 in CaCl2 brine in different thermodynamic conditions is critical. In this study, CO2 solubility in 0, 1.90 and 4.80 mol/L CaCl2 solutions at 328.15 to 375.15 K and 68.9 to 206.8 bar were measured. These values are normal for oil reservoirs. A popular thermodynamic model is available in the literature for estimating the CO2 solubility in pure water and NaC1 solutions. In this paper, the available model was modified by experimental work to be applicable for CaCl2 as well. Based on the measured data, the component interaction parameters in the base model were adjusted for a CaCl2-H2O-CO2 system. The developed model could predict CO2 solubility in different conditions with remarkable accuracy, particularly for high concentration solutions and at high pressures. This improvement is up to 65% better than in the base model. This model can be used in Darcy scale models for predicting wormhole propagation during carbonate matrix acidizing.

A compositional model for CO_(2) ooding including CO_(2) equilibria between water and oil using the Peng–Robinson equation of state with the Wong–Sandler mixing rule

This paper presents a three-dimensional, three-phase compositional model considering CO2 phase equilibrium between water and oil. In this model, CO2 is mutually soluble in aqueous and hydrocarbon phases, while other components, except water,exist in hydrocarbon phase. The Peng–Robinson(PR) equation of state and the Wong–Sandler mixing rule with non-random two-liquid parameters are used to calculate CO2 fugacity in the aqueous phase. One-dimensional and three-dimensional CO2 flooding examples show that a significant amount of injected CO2 is dissolved in water. Our simulation shows 7% of injected CO2 can be dissolved in the aqueous phase, which delays oil recovery by 4%. The gas rate predicted by the model is smaller than the conventional model as long as water is undersaturated by CO2, which can be considered as 'lost' in the aqueous phase. The model also predicts that the delayed oil can be recovered after the gas breakthrough, indicating that delayed oil is hard to recover in field applications. A three-dimensional example reveals that a highly stratified reservoir causes uneven displacement and serious CO2 breakthrough. If mobility control measures like water alternating gas are undertaken, the solubility e ects will be more pronounced than this example.