Study On The Synthesis Kinetics Of Glycerol Laurate And The New Rpb Synthesis Process

Glycerol monolaurate(GML)is an ester compound with excellent emulsification and biological inhibition,which is mainly used as an additive in food,medicine and cosmetics.At present,the main synthesis methods of GML are direct esterification and transesterification.Because the process of preparing GML by direct esterification of glycerol(GL)and lauric acid(LA)is relatively simple,it is widely used in industry.Since three hydroxyl groups in glycerol molecule can react with LA,the esterification process will occur in series with secondary esterification and tertiary esterification.In addition,the esterification products undergo processes such as isomerization and reversible hydrolysis,resulting in a more complex reaction process in the entire system.The existing literature on the analysis of esterification reaction networks and the kinetics of related reactions is not yet sufficient.However,the kinetic results are of great significance for reactor design and optimization of operating conditions.Esterification is a typical reversible reaction,where the removal of water generated by the reaction affects the rate and degree of reaction progression towards the forward direction.Therefore,enhancing the water removal during the synthesis of GML is expected to improve the conversion rate of the system.Based on the above issues,the reaction kinetics of esterification of GL with LA was studied in this thesis,and a new method of rotating packed bed(RPB)enhanced synthesis of GML was proposed.The main results of the thesis are as follows.(1)A complete direct esterification reaction kinetics model has been established,and the correlation coefficient(R~2)between the experimental data and the model is generally above 0.99,which proved the reliability of the model.The kinetic process of esterification reaction was systematically studied when p-toluenesulfonic acid was used as catalyst,and the results showed that the catalyst can significantly increase the esterification reaction rate.When a 2%(molar fraction)catalyst is added,the reaction rate can be increased by about 10times.The three series esterification reaction rates are all in the same order of magnitude,with the single esterification reaction rate is approximately twice that of the double esterification reaction rate and 6 times that of the triple esterification reaction rate.The reaction order of all esterification reactions is 1for glycerol,lauric acid and p-toluene sulfonic acid catalysts.The experimental results showed that the activation energy of single esterification reaction was37.72 kJ/mol,and the activation energy of double esterification reaction was32.24 kJ/mol.It was proved that isomerization reaction between GML and glycerol dilaurate(GDL)isomers was an equilibrium reaction and the reaction rate was faster than that of the esterification reaction.(2)The performance of RPB coupled with nitrogen stripping to enhance GML synthesis was investigated experimentally.Firstly,the effects of nitrogen flow rate and stirring speed on esterification reaction were experimentally investigated in the stirred tank reactor(STR).Then the effects of circulating flow rate,high gravity level and nitrogen flow rate on esterification were investigated in the RPB,and the optimal reaction conditions were optimized.By comparing the results of two device,it was found that the esterification reaction rate can be significantly improved,and the reaction time was shortened by 40%.Under the experiment conditions of this thesis,whether in the STR or RPB,it was found that the above experimental factors only affect the conversion rate of LA,and have no effect on the maximum yield of GML,which is about 43%.