Simulation And Experiment Of Bio-butanol Extractive Separation With Ionic Liquids

Bio-butanol as a potential biofuel and widely used chemical material has attracted more and more attentions.The commonly used separatting method of liquid-liquid extraction exist the problems of low extracting effect,low screening efficiency and unclear mechanism in the extracting process.Therefore,the develop of new and energy-saving extractants and extracting method and the select of efficient screening method are of great significances to break the shackles of existing extraction technology and promoting the development of industry.Combining with the thermodynamic prediction,the liquid-liquid phase verification and process simulation,the screening method,the extraction performance and screening rule in the process within 1-butanol plus water binary system and model fermentation broth fromed by acetone,1-butanol,ethanol(ABE for short)and water were systematically studied,due to the low 1-butanol content in fermentation broth.Additionally,the improvements of predictive model in the screening were conducted.Meanwhile,the extraction of new aqueous two phase(ATP)system on bio-butanol was explored,and the extracting conditions were optimized.Finally,the site,way and strength of the interactions between the molecules were uncovered by the means of quantum calculation,H1 NMR and molecular dynamics simulation.A suitable extractant named [HMIM][FEP] is selected from 1200 kinds of ionic liquids.The selected extractant performs well both in the binary system and the model fermentation broth.The order of extracting performance from other existing extractants is: [HMIM][FEP] > K3PO4 > [HMIM][PF6] > mesitylene > oleyl alcohol.An instructive screening rule for bio-butanol extraction is summarized and builded.Also,the new hybrid separation process of extraction and distillation is more concise and less investmental.The extractant consumption and the energy consumption are reduced by 10% and 4.4% when compared with the referenced process who utilizes mesitylene as extractant.The LLE experiment was conducted to verify the feasibility and practicability of the predictive model,and the improvements of model were conducted based on this.The predictions calculated at parameterization level of BP-TZVPD fine in the C30-1701 version using the BP functional at def2-TZVPD quantum level is closer to the experimental values when dealing with the ionic liquid as the form of multiple conformations and ion pair.The calculated root mean square deviation is about 4.9%.The [BMIM][Cl]-K3PO4 ATPs owns the best separation effect and the 1-butanol can be enriched into the upper phase fully.Meanwhile,the good extraction effects on acetone and ethanol are also obtained with partition coefficients greater than 20.It is also found that the separation effect of ATP extraction is determined by the type and concentration of inorganic salt and the structures of ionic liquids.The separation effects are beneficial to the inorganic salt with strong phase forming ability,high concentration and ionic liquid with short side chain of cation and small volume of anion.The extracting mechanism investigation shows that the interaction between[HMIM][FEP] and 1-butanol is stronger than that between 1-butanol and water or mesitylene.The addition of [HMIM][FEP] can break the interaction formed between1-butanol and water.The addition of kosmotropic salt attracts the water to form a‘hydration shell' around it,and the 1-butanol molecule is repelled out of the system by the new and stronger interaction formed between the polar group of 1-butanol and the chaotropic salt in the ATP extraction process.Finally,the bio-butanol is extracted.