Separation of ethyl acetate–isooctane mixture by heteroazeotropic batch distillation

Heteroazeotropic batch distillation process to recover isooctane as product from ethyl acetate–isooctane mixture with using acetonitrile. 3.0-2 class ternary diagram and liquid–liquid and liquid–liquid–vapour equilibrium envelopes estimated by the original UNIFAC model. •Distillation of isooctane from an ethyl acetate–isooctane mixture.•Heterogeneous azeotropic distillation in a batch rectification column.•Methanol and acetonitrile heterogeneous entrainers selected among 60 candidates.•Experiments carried out in a laboratory scale column with decanter at the top.•Isooctane is the distillate product while acetonitrile achieves the best separation. This paper studies the separation of an ethyl acetate–isooctane mixture by heterogeneous azeotropic distillation in a batch rectifying column. An initial list of 60 candidates was studied but only methanol and acetonitrile were obtained as potential heterogeneous entrainers. These entrainers form a low boiling heterogeneous azeotrope with isooctane. Experimental verification of the miscibility gap with isooctane was performed at 25°C for each entrainer giving a smaller region for methanol than for acetonitrile. Feasibility of the heterogeneous azeotropic batch distillation was carried out experimentally in a laboratory batch distillation column having 44 theoretical equilibrium stages and using a high reflux ratio. Several distillate fractions were taken as a function of the temperature at the top of the column. For both methanol and acetonitrile, the main fraction was defined by the condensed vapor providing a liquid–liquid split of the isooctane/entrainer heteroazeotrope into the decanter. Ethyl acetate impurity was detected in both decanted phases, but in much lower amount when using acetonitrile as entrainer. The process with acetonitrile also resulted in a shorter operating time and higher purity and recovery yield of isooctane as the main distillate product. Pure ethyl acetate remained into the boiler at the end of each process.