Purification of isopropyl alcohol by heterogeneous azeotropic distillation

Abstract

The ternary liquid system of isopropyl alcohol - water - cyclohexane was studied. For improving the efficiency of distillation process by using CHX as an entrainer, the suitable operating conditions of heterogeneous azeotropic distillation for dehydration of isopropyl alcohol in industrial scale were found. The first was the study of the phase behavior of ternary liquid system for isopropyl alcohol - water - cyclohexane at different concentrations. The solubility curve and plait composition at temperatures of 26⁰C and 30⁰C were determined. At the plait point of 26⁰C, the compositions are 27.08% isopropyl alcohol, 47.04% cyclohexane and 25.88% water by weight. At the plait point of 30⁰C, the compositions are 27.58% isopropyl alcohol, 46.72% cyclohexane and 25.70% water by weight. The second part was the finding of the suitable operating conditions of industrial scale heterogeneous azeotropic distillation by varying the feed rate and reflux rate. The suitable feed rate and percent reflux rate are 11.0 L/min and 98 percent, respectively and the purity of isopropyl alcohol is 99.955%. At this condition, cyclohexane loss is lowest. The top product compositions were calculated by material balance method. The top product compositions are 12.13% isopropyl alcohol, 84.16% cyclohexane and 3.71% water by weight.