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Thermodynamic Research On Phase Equilibrium In Separation Process Of Dinitronaphthalene Isomer Via Solvent Crystallization

Posted on:2018-04-09Degree:MasterType:Thesis
Country:ChinaCandidate:C B DuFull Text:PDF
GTID:2321330518969398Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
1,5-Dinitronaphthalene and 1,8-dinitronaphthalene are important intermediates for synthetic dyes,pigments,pharmaceuticals,pesticides,photographic materials and advanced polyurethanes.Especially,a large amount of polyurethane materials used at home and abroad results the increase in 1,5-dinitronaphthalene market demand year by year.Therefore,they have broad market prospects.Up to yet,the industrial method for producing 1,8-dinitronaphthalene and 1,5-dinitronaphthalene is nitration of naphthalene with mixture of concentrated nitric acid and concentrated sulfuric acid.Nevertheless,the nitration product acquired with this method is the isomeric mixtures of 1,8-dinitronaphthalene and 1,5-dinitronaphthalene.Solvent crystallization of separating 1,5 and 1,8-dinitronaphthalene mixtures is an effective method,but this method needs more comprehensive accurate solubility data.The solubility of 1,5-dinitronaphthalene in methanol,ethanol,1-propanol,acetonitrile,trichloromethane,acetone,toluene,ethylbenzene,ethyl acetate,N-methyl-2-pyrrolidone(NMP)and N,N-dimethylformamide(DMF)and of 1,8-dinitronaphthalene in methanol,ethanol,isopropanol,1-butanol,acetonitrile,trichloromethane,acetone,toluene,ethyl acetate,NMP and DMF were measured by using isothermal dissolution method within temperature range from(273.15 to 343.15)K under atmospheric pressure of 101.1 kPa.At the same temperature,the order of the solubility of 1,5-dinitronaphthalen from high to low in different organic solvents was:NMP>DMF>trichloromethane>toluene>(ethyl acetate,acetone)>ethylbenzene>acetonitrile>1-propanol>ethanol>methanol;and of 1,8-dinitronaphthalen,NMP>DMF>acetone>(ethyl acetate,acetonitrile)>trichloromethane>toluene>methanol>ethanol>isopropanol>1-butanol.The solubility data were correlated by ?h equation,Apelblat equation,Wilson equantion and NRTL equation.The largest values of RAD and RMSD were 4.46%and 37.90×10-4,respectively.In addition,the mixing Gibbs energy,mixing enthalpy,mixing entropy,activity coefficient at infinitesimal concentration(?1x)and reduced excess enthalpy(H1E,?)were obtained by using Wilson model.The solubility of 1,5 and 1,8-dinitronaphthalene in binary(acetonitrile + methanol),(acetone + methanol)and(toluene + methanol)solvent mixtures were investigated by the equilibrium method within temperature range from(273.15 to 313.15)K under atmospheric pressure of 101.1 kPa.The solubility of 1,5 and 1,8-dinitronaphthalene increased with increased temperature and mass fraction of acetone or acetonitrile for the systems acetone + methanol and acetonitrile + methanol.For the toluene + methanol system,at the same temperature,they increased at first and then decreased with an increased in mass fraction of toluene.The experimental solubility data were correlated by Jouyban-Acree model,van't Hoff-Acree model,modified Apelblat-Acree model,Sun model and Ma model.The largest values of RAD and RMSD were no more than 4.55%and 6.03×10-4,respectively.The calculated solubility values agreed very well with the experimental ones.In addition,the preferential solvation parameters of 1,5 and 1,8-dinitronaphthalene in these three mixed solvents were obtained.In the acetone +methanol mixtures with composition 0<X1<0.4 and acetonitrile + methanol mixtures with composition 0<x1<0.35,the ?x1,3 values were negative indicating preferential solvation of 1,5 or 1,8-dinitronaphthalene by acetone or acetonitrile.While in the acetone + methanol mixtures with composition 0.4<x1<1 and acetonitrile + methanol mixtures with composition 0.35<x1<1,the ?x1,3 values were positive indicating preferential solvation of 1,5 or 1,8-dinitronaphthalene by methanol.For the toluene + methanol system,1,5 or 1,8-dinitronaphthalene molecules were first solvated by toluene when methanol was added to toluene and then solvated with methanol.The solubility for ternary system of 1,5-dinitronaphthalene-1,8-dinitronaphthalene-NMP/DMF were measured by Schreinemaker's method at three temperatures of 313.15 K,328.15 K and 343.15 K,and the corresponding ternary phase diagrams were constructed.The crystallization regions of 1,8-dinitronaphthalene and 1,5-dinitronaphthalene decreased as temperature increased.At the same temperature,the crystallization region of 1,5-dinitronaphthalene was larger than that of 1,8-dinitronaphthalene.1,5-Dinitronaphthalene could be easily crystallized from the isomeric mixtures of 1,5-dinitronaphthalene and 1,8-dinitronaphthalene in the solvent of NMP or DMF The solubility of ternary system was correlated by NRTL model and Wilson model.The error of the experimental value and the calculated value of Wilson model and NRTL model were very little.The maximum root-mean-square deviations were 7.38×10-3 and 7.26×10-3,respectively.It illustrated that the two equations could all be used to correlate the 1,5-dinitronaphthalene-1,8-dinitronaphthalene-NMP/DMF ternary systems.
Keywords/Search Tags:1,5-Dinitronaphthalene, 1,8-Dinitronaphthalene, Solubility, Phase equilibrium, Phase diagrams, Thermodynamics, Preferential solvation
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