The adsorption properties of NaY zeolite for separation of ethylene glycol and 1,2-butanediol: Experiment and molecular modelling

Abstract

The separation of ethylene glycol (EG) and 1,2-butanediol (1,2-BDO) azeotrope in the synthesis process of EG via coal and biomass is becoming of increasing commercial and environmental importance. Selective adsorption is deemed as the most promising methods because of energy saving and environment favorable. In this paper, NaY zeolite was used to separate 1,2-BDO from EG, and its adsorption properties was then investigated. The isotherms of EG and 1,2-BDO in vapor and liquid phases from 298 to 328 K indicated that they fitted Langmuir model quite well, and the NaY zeolite absorbent favored EG more than 1,2-BDO. The Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation techniques were conducted to investigate the competition adsorption and diffusion characteristics in different adsorption regions. It was observed that EG and 1,2-BDO molecules all have the most probable locations of the center of the 12-membered ring near the Na cations. The diffusivities of EG are lower than those of 1,2-BDO at the same adsorption concentration. At last, the breakthrough curves of the binary mixture regressed from the empirical Dose–Response model in fixed-bed column showed that the adsorption selectivity of EG could reach to as high as 2.43, verified that the NaY zeolite could effectively separate EG from 1,2-BDO. This work is also helpful for further separation of other dihydric alcohol mixtures from coal and biomass fermentation.