Development of a reactive extraction process for enhancing acetalizations of ethylene glycol and 1,2-butanediol with propyl aldehyde

Ethylene glycol (EG) is a widely used industrial chemical material, and integrated chemical-looping separation technology (CLS) was verified effective to remove 1,2-butanediol (1,2-BDO) and recover EG produced via the syngas to EG route. Thermodynamic experiments were carried out and employed to analyze the vapor–liquid and liquid–liquid behaviors of the system. Propyl aldehyde, apart from as the reactant, also shows excellent performance in water removal and acetals extraction. Based on the results of the thermodynamic analysis, a reactive extraction process was proposed to intensify the acetalization of EG and 1,2-BDO mixture with propyl aldehyde. The reactive extraction model was established on Aspen Plus v11, and the effects of flow mode (co-current and counter-current), number of stages, the feed-in mole ratio of aldehyde to DIOL on the conversions of EG and 1,2-BDO, the recovery of 2-ethyl-1,3-dioxolane (2ED), and the purity of acetals were investigated. Results show that co-current flow mode performs better than counter-current flow mode and an aldehyde to DIOL feed-in mole ratio of 1.35 to 1 is sufficient. The whole flowsheet, which consists of a seven-stage reactive extraction column and two distillation columns, was designed and optimized. Remarkably, the conversions of EG and 1,2-BDO are over 0.95 and the recovery of 2ED is 0.999 with the aldehyde to DIOL stoichiometric coefficient, which indicates the effectiveness of this process and provides fundamental data and guidance for industrial application.