Intelligent Design And Application Research Of Extractants Based On Molecular Structure

With the vigorous promotion of the clean and efficient use of oil and energy in China,separation is playing an increasingly important role in the process industry in the purification of raw materials,product purification and waste treatment.In the petrochemical industry,it is common to encounter systems where the relative volatility of the components to be separated is close to 1 or azeotropes are formed,extractive distillation and liquid-liquid extraction are common and effective methods for such difficult separation systems.The choice of extractant is crucial.An intelligent design method of extractant based on the molecular structure was proposed for the molecular design of extractants in extractive distillation and liquid-liquid extraction.Firstly,two groups of physical indicators were determined for the factors affecting the separation performance of extractive distillation and liquid-liquid extraction extractants.Seven index vectors were used for extractive distillation extractants,which were solubility,relative volatility,enthalpy of evaporation,heat capacity,molar mass,boiling point,and melting point.For liquid-liquid extraction solvents,six index vectors were used,which were partition coefficient,selectivity,solvent loss,molar mass,boiling point,and melting point.Based on the above physical properties,a predictive model of extractant physical properties was established.Secondly,an extractant design method based on elements and chemical bonds was proposed.The elements and chemical bonding groups were pre-selected.And the molecules were automatically synthesized according to certain combinatorial rules using a knowledge-based molecular design method.The problem of the "combinatorial explosion" of molecules was avoided.The target properties of the extractant were set and the extractant that can meet the requirements was selected by predicting the relevant physical properties of the generated molecules.Based on the fuzzy and multi-indicator nature of extractant evaluation,the fuzzy comprehensive evaluation method was used to evaluate the extractant.Based on the separation performance of extractants and the relative importance of each index,the fuzzy comprehensive evaluation affiliation function was established.And the weight proportion of each index was determined by hierarchical analysis.Then,a molecular design program based on the knowledge-based method was written using the numerical calculation function of C++ language under Visual Studio2010.Developed an extractant intelligent design system using the MFC framework to design the program interface.It realized the functions of automatically determining the effective separation method of binary systems to be separated,intelligently synthesizing molecular structures,and outputting extractant molecules that satisfy the conditions.Finally,an intelligent design study of extractants was conducted for n-butane-n-butene extractive distillation and benzene-cyclohexane liquid-liquid extraction using the developed extractant intelligent design system.The accuracy of the molecular design results of this system was demonstrated by comparing the results with those reported in the literature.The intelligent design method of extractant proposed can design a variety of alternative extractant and improve the flexibility of the user in selecting extractant.The application research has proved that the intelligent design system of extractant developed is reliable and practical,and has important theoretical significance and application value.