Separation Of Azeotropic Mixture Of Methanol-acrylonitrile-water By Heterogeneous Batch Extractive Distillation

The separation of methanol and acrylonitrile by heterogeneous batch extractive distillation was studied via theoretical analysis, experiment and simulation.The most adopted and simple approach of selecting solvent, which integrates qualitative screening and selection methods, was applied. And water was finally selected as the best solvent. The vapor-liquid binary equilibrium data of the system of methanol-acrylonitrile were obtained by the vapor-liquid equilibrium experiments at ambient pressure. The experimental results were tested for thermodynamic consistency. And the vapor-liquid binary equilibrium data of the system of methanol- water and acrylonitrile-water were obtained from the literature. The parameters of NRTL were correlated by the experimental and literature data through the NRTL-RK mixing model. Estimating the liquid-liquid ternary equilibrium by UNIFAC group contribution method gives more accurate results.The heterogeneous azeotropic batch extractive distillation is an integrated process of heterogeneous batch distillation and extractive distillation, which is a brand-new research subject. To comprehend the process and guide the design, the feasibility analysis of the process was carried out by using a simplified differential model in the extractive section, first chose feed stage and feed policy of solvent, reflux policy and feasibility criteria, then studied the feasibility of each step of the column using the extractive profile curve maps, deriving the feasible areas and the proper range of the solvent ratio to vapor and the reflux ratio.The heterogeneous batch extractive distillation process for the separation of the azeotropic mixture of methanol-acrylonitrile by water as solvent was simulated via ASPEN commercial software. The effects of operation parameters such as the volume of decanter, reflux ratio, solvent ratio to vapor, theoretical stages and feed stage of solvent were obtained by simulation. The heterogeneous batch extractive distillation experiment was also simulated, and the experiment results agreed well with those simulated.