Study On The Reactive Crystallization Process Of Sebacic Acid

Sebacic acid is a member of dicarboxylic acid family and is an important chemical material.It is widely used in many fields,such as fine chemicals,pharmaceutical,materials industries and cosmetics.The production of sebacic acid in China is large,however,the products have some quality issues such as low purity,irregular shape,small size,uneven distribution of particle size as well as long duration of industrial production.In this context,the thermodynamic,crystal morphology and crystallization process of the reaction crystallization process of sebacic acid were systematically studied in this paper,which provided technical support and theoretical basis for the industrial production of sebacic acid.In this paper,firstly,the solubility data of disodium sebacate in three kinds of water + organic solvent mixtures,including(water + methanol),(water + acetone)and(water + DMF)as well as water,were experimentally determined by a gravimetric method.The modified Apelblat equation,the λh model and the NRTL model were applied to correlate the solubility data in binary solvent mixtures.In addition,the dissolution thermodynamic properties of disodium sebacate in different binary solvent mixtures were also calculated and discussed based on the NRTL model and experimental solubility data.Secondly,the BFDH model and AE model were used to predict the crystal habit of sebacic acid,the great differences between the vacuum state and the actual condition indicated that the sebacic acid is affected by the external environment.So the effects of organic solvents,agitation types,polymer additives and non-polymer additives on the morphology of sebacic acid were explored.The results showed that all the above conditions had a significant effect on the morphology of sebacic acid.Through a series of characterization,the interaction mechanism between the polymers and dicarboxylic acids proposed by Klapwijk et al.was verified,and the crystal habits were explained qualitatively from the molecular level.Finally,on the basis of the theoretical study above,the crystallization process of sebacic acid was studied.The effects of operating parameters such as reaction temperature,cooling rate and initial concentration on the crystal habit,particle size distribution,purity and process yield of sebacic acid were investigated,and the optimized crystallization process conditions were determined.The products prepared by the optimized crystallization conditions have large average particle size and uniform particle size distribution,and the yield is high.