Separation of acetonitrile/methanol/benzene ternary azeotrope via triple column pressure-swing distillation

•TCPSD for separating acetonitrile/methanol/benzene was investigated.•Feasibility of TCPSD to separate ternary system was analyzed by triangular diagrams.•Process parameters were optimized using Aspen Plus and Visual Basic.•The best sequence of TCPSD was obtained based on economics.

Acetonitrile/methanol/benzene mixture forms more than one different azeotropes and its triangular diagram presents several distillation boundaries at atmospheric pressure. A process named as triple column pressure-swing distillation (TCPSD) was proposed to separate this complex ternary system. The feasibility of the process was confirmed using residue curve maps and rigorous steady-state simulations were implemented on Aspen Plus. On basis of minimum total annual cost, several operating parameters were optimized by pressure-swing optimization software using the sequential iterative optimization procedure and the economics of TCPSD were compared with four different separation configurations. The results demonstrated that the A-M-B separation configuration was the most optimal column sequence in global optimization to separate acetonitrile/methanol/benzene azeotropic mixture using TCPSD. TCPSD may arouse the interest of researchers in various fields and can assist engineers to select the optimal separating process.