Catalytic Synthesis Of Di-n-octyl Nylon-acids And Its Reaction Kinetics

Heteropoly acid(salts)with its extraordinary acidic, " pseudoliquid phase" behavior and high activity with low temperature, high stability, etc., and the catalytic process of cleaning environmental protection, in recent years,it gained extensive attention in the field of catalysis, since it was one type of green catalyst with extremely broad development prospect.As a by-product of the production process of adipic acid, Nylon acid had not been well exploited and utilized. Nylon acid can be used as raw materials for the synthesis of aliphatic dicarboxylic acid esters,which were cold-type plasticizers with its excellent performance and widely used in the plastics industry. This industry developed rapidly in recent years with bright prospects, the demand for nylon acid were rising year by year.Synthesis process of di-n-octyl nylon acid ester was researched systematically. it was prepared from nylon acid supplied by ShenMa co. Ltd.and n-octanol as reactant, by using environment-friendly phosphotungstic acid as catalyst and toluene as azeotropic agent.Molar ratio of n-octanol to adipic acid,amount of catalyst,amount of azeotropic agent and reaction time were studied according to uniform design.The optimum reaction condition optimized by single-factor experiment were:the molar ratio of alcohol to acid 2.8:1,amount of catalyst and water entrainer were 1.2% and 75% by mass of nylon acid,reaction time 3 hours.under this condition,the yield of di-n-octyl nylon acid ester could reach 99.18%.System of esterification catalyzed by phosphotungstic acid was proved to be mild and environment-friendly with small catalyst dosage and high yield of esterification, the after-treatment of the product was simple and the color of the product was excellent. In all, it is an effective way to realize the well Utilization of nylon acid.The experiments of esterification reaction kinetics were carried out with toluene as water entrainer, esterification yield of synthesis systems of di-n-octyl succinate, di-n-octyl glutarate and di-n-octyl adipate were determined at different time separately, a thorough kinetic study about the reaction of esterification was carried on according to the consecutive reaction laws. Finally, a kinetics equation was got which can accurately describe the reaction convertion rate with the change of reaction time, reaction temperature and ratio of alcohol to acid in the experiment. Parameters in kinetics equations was determined. Result showed that three reactions of esterification all obeyed second-order irrevisible kinetics model under the experimental conditions. It proved that the reaction kinetics model we got was reliable and could be used to guide the industrial practices.