Properties of symmetric 1,3-diethers based on glycerol skeletons for CO2 absorption

Abstract

CO2 absorption is at the forefront of separation processes due to the attention given to greenhouse gas emission control and its potential to slow global climate change. This report describes the study of new physical solvents for CO2 absorption through a single step etherification of epichlorohydrin, yielding symmetric 1,3-diethers based on a glycerol skeleton. Five such compounds were obtained in this manner: 1,3-dimethoxypropan-2-ol (DMP, 623-69-8), 1,3-diethoxypropan-2-ol (DEP, 4043-59-8), 1,3-di(propan-2-yloxy)propan-2-ol (DIPP, 13021-54-0), 1,3-bis(2-methoxyethoxy)propan-2-ol (DMEP, 130670-52-9), and 1,3-bis(2,2,2-trifluoroethoxy)propan-2-ol (DTEP, 691-26-9). Screening of synthesis methods was conducted and aqueous sodium hydroxide solution was found to be the best reaction medium. All compounds were purified through rigorous distillation and drying techniques. Density and viscosity values for each compound were collected in the range of 293.15–353.15 K. CO2 absorption capacities of these solvents were measured at 303.15, 318.15, 333.15 and 348.15 K at CO2 partial pressures in the range of 2–6 atm. Miscibility of these compounds with common organic solvents and water was also determined. Dipole moments were calculated for exploration of structure – property relationship. Among these solvents, DMEP and DTEP exhibited the largest affinity for CO2 with Henry's constants of 48.0 and 45.4 atm, respectively, at 303.15 K, reaching the same level as diglyme used industrially while allowing further modification for improvement in CO2 capture ability. Data obtained in this work should be useful as a guide for further design and synthesis of solvents based on glycerol skeletons for CO2 absorption applications.