Efficient esterification of n butanol With acetic acid using green solvents

Abstract

Ionic Liquids (ILs) and deep eutectic solvents (DESs) provide an important alternative in the conventional esterification process. A total of 42 cations and 32 anions resulting in 1344 possible combinations were screened via the COnductor Like Screening Model for Real Solvents (COSMO-RS Model). The esterification reactants and products, n-butanol (n-BuOH), acetic acid (HAc) and n-butyl acetate (n-BuAc) in different combination of cation and anions were used to predict the activity coefficient at infinite dilution (IDAC) with the help of screening charge density. From the predicted IDAC values, the capacity (C), selectivity (S) and performance index (PI) were calculated to screen potential ILs for the green esterification process. Results revealed that 1-ethyl-3-methylimidazolium hydrogen sulphate, {[EMIM][HSO4]}, 1-ethyl-3-methylimidazolium ethyl sulphate, {[EMIM][EtSO4]}, 1-butyl-3-methylimidazolium acetate, {[BMIM][OAc]} and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, {[BMIM][NtF2]} gave a high solvent selection parameters values and therefore these ILs were chosen for further experimentation. In addition, deep eutectic solvents (DESs) a new green solvent were also been used in the experimental work to increase the conversion of n-butanol and yield of n-butyl acetate (n-BuAc) at 298.15 K and 1 atm. newlineFurther, density and solution thermodynamic properties of 33 binary mixtures were measured and calculated over the entire mole fractions at different temperatures from 293.15 K to 343.15 K. From these results, it was observed that {[EMIM][HSO4]}, {[EMIM][EtSO4]}, {[BMIM][OAc]}, {[ChCl][Gly]} and {[ChCl][HAc]} with n-butanol (n-BuOH), acetic acid (HAc) and water had strong molecular interactions from the mole fraction 0.3 (for HAc) to 0.7 (for n-BuOH). newline