Study of Mixtures of 1,3-Propanediol+DBU and DBU+Sulfolane for a New Sustainable Solvent for CO 2 Removal

CO 2 removal, especially the one applied to reduce the emissions of CO 2 to the atmosphere (carbon capture, utilization, and storage), is one of the main research topics nowadays because of its great contribution to the reduction in climate change and to making many industrial processes sustainable. In this regard, alternative solvents to the traditional ones are under study with the aim of employing a more sustainable solvent for the environment, health, and society, in comparison with the traditional amine aqueous solutions that are toxic and corrosive. The CO 2 -binding organic liquids (CO 2 -BOLs) are a class of components of interest. In this work, the vapor–liquid equilibrium (VLE) data for two newly selected binary mixtures based on CO 2 -BOLs, 1,3-Propanediol+DBU and DBU+Sulfolane, have been experimentally determined at the Process Thermodynamics laboratory (PT lab) of Politecnico di Milano to evaluate the suitability of these mixtures for being a solvent for CO 2 removal. All the experiments have been carried out by using the Fischer ® Labodest ® VLLE 602 unit at a constant pressure of 30 kPa. The densities of the mixtures for all the considered compositions have been determined at atmospheric pressure with a density meter (Mettler Toledo Densito Density2Go). No data on the VLE of these mixtures can be found in the literature. This is the first work focusing on mixtures of these components that could be employed as solvents for CO 2 removal as alternative solvents to the monoethanolamine (MEA) aqueous solution in the process of chemical absorption. The collected experimental data have then been used for the definition of the thermodynamic model by considering different possible theories (NRTL, Wilson, and UNIQUAC) that could be employed for the representation of the two systems.