Heterogeneous thermodynamic comparison of the tert-butyl glycerol ether synthesis from glycerol via olefin etherification or alcohol dehydration

Abstract

On the basis of the principle of Gibbs free energy minimization, a genetic algorithm was used to carry out a comparative study on the heterogeneous thermodynamics of the glycerol etherification with isobutanol, and the glycerol dehydration with tert-butanol to butyl glycerol ethers. Under the conditions in the temperature range of 40-300 °C, the pressure range of 0.1-0.7 MPa, the feed of 100 mol of glycerol + 600 mol of other reactant, the effects of temperature and pressure on the equilibrium conversions, product selectivities and gas-liquid equilibrium composition were investigated. The results show that for the etherification process, low temperature is conducive to the generation of tri-tert-butyl glycerol ether, while high temperature is conducive to the generation of di-tert-butyl glycerol ether and mono-tert-butyl glycerol ether. The elevated pressures promote the formation of tri-tert-butyl glycerol, while inhibit the production of di-tert-butyl glycerol ether and mono-tert-butyl glycerol ether. For the dehydration process, the equilibrium conversion of glycerol is close to 100%, the selectivity of tri-tert-butyl glycerol ether is more than 90%, the selectivity of di-tert-butyl glycerol ether is less than 10%, and mono-tert-butyl glycerol ether is efficiently converted. The results also show that for the dehydration process, increasing the pressure moves the heterogeneous temperature range to the right, and the liquid phase composition can be adjusted by changing the pressure.