Comparison of Pressure-Swing and Extractive-Distillation Methods for Methanol-Recovery Systems in the TAME Reactive-Distillation Process

The process to produce tert-amyl methyl ether via reactive distillation requires a methanol-recovery section because the presence of C5-methanol azeotropes means that a significant amount of methanol is present in the distillate from the reactive column. The use of pressure-swing azeotropic distillation was studied in a previous paper [Al-Arfaj, M. A.; Luyben, W. L. Plantwide control for TAME production using reactive distillation. AIChE J. 2004, 50 (7), 1462] in which both the steady-state design and the plantwide control of the entire process were developed. This paper presents a quantitative steady-state and dynamic comparison of the pressure-swing process with an extractive-distillation process. Water is the extractive agent. The extractive-distillation process is found to be much more economical (40% lower capital investment and 60% lower energy cost). The plantwide dynamic controllability performances of the two systems are essentially equivalent.