Molecular mechanism of efficient separation of isopropyl alcohol and isooctane by extractive distillation

Abstract

In this paper, a method of extracting isopropyl alcohol and isooctane system from industrial wastewater of fuel oil by extractive distillation is proposed to realize resource utilization of waste and reduce environmental pollution. Isooctane and isopropyl alcohol are both products obtained from petroleum refining, which are widely used in many fields. In this study, the quantum chemical was used to determine that glycerol (Gl) and N, N-dimethylacetamide (DMAC) were the best extractants to separate Isopropanol and isopropyl alcohol. The intermolecular electrostatic interaction and reaction site between the extractant and the system were determined by electrostatic potential (ESP) analysis. Inter-complex compounds and weak interactions were analyzed by interaction region indicator (IRI). The independent gradient model based on Hirschfeld partition (IGMH) was used to visualize the electron density of the molecule. Meanwhile, the simulation process of azeotropic mixture separation of IPA and ISO by extractive distillation was established, and the process was optimized by a sequential iterative method. The economic and environmental were used to evaluate and analyze the process, and the azeotropic mixture separation was realized. Compared with Gl, the extractive distillation separation of isopropyl alcohol and isooctane by DMAC reduces the total annual cost by 5 %, energy consumption, and reduces the greenhouse gas emissions by 1 %, and has greater environmental protection and economic benefits. This work is guided by quantum chemical calculation and reveals the interaction mechanism of solvent separation azeotropic mixture from the microscopic level, which provides an important reference value for realizing high efficiency, energy saving, and green separation of azeotropic mixture in industry.