The oxygenation of alkyl chains is a well-known approach for enhancing the CO2 sorption, being even the basis of the two most successful industrial processes for natural gas sweetening (Rectisol and Selexol). Nevertheless,... [ view full abstract ]
The oxygenation of alkyl chains is a well-known approach for enhancing the CO2 sorption, being even the basis of the two most successful industrial processes for natural gas sweetening (Rectisol and Selexol). Nevertheless, even though some glymes, glycols and polymers present enhanced CO2 solubilities, the sorption mechanism is still unclear. Thus, prior to the application of these compounds to novel carbon capture and storage (CCS) technologies, an accurate description of their thermodynamic behavior is necessary for the optimal design and simulation of new processes.
In this work, a throughout thermophysical characterization of glycols and glymes was carried by measuring the densities and derivative properties of a large set of glycols and glymes in a wide pressure and temperature ranges. These compounds were selected aiming to evaluate the influence of different structural effects, such as the chain length increase and the replacement of hydroxyl end groups by methyl or ethyl groups, on the thermophysical properties. The experimental data measured along with vapor liquid equilibrium (VLE) data gathered from literature were used to develop a new molecular model within the framework of soft-SAFT for these polyethers. The accuracy and robustness of the proposed model was shown by the accurate description of different pure fluid properties (VLE, pρT and derivative properties), as well as through the description of the phase equilibria of different mixtures. Moreover, the transferability of the model to higher chain length members, not included in the model parameterization (e.g. PEG400 , PEGDME250), was evaluated and the assumptions within the model shown to remain valid. Ultimately, the model and molecular parameters were used to describe the CO2 solubilities in the glymes, allowing an accurate description of the experimental data using only one single binary interaction parameter close to unity, temperature and pressure independent, that was further correlated with the glymes’ molecular weight.
