Study On Kinetics And Technology Of Direct Hydration Of Dihydromyrcene

Dihydromyrcenol is a kind of important spices,which is widely used in living goods such as detergent,indoor air freshener and so on.Dihydromyrcenol had a significant market share of the perfume market.The annual usage for dihydromyrcenol continues to rising suggesting a broad market prospects.The liquid acid catalysts,typically sulfuric acid,were often adopted in the early processes of the direct hydration of dihydromyrene.However,these processes have caused the serious corrosion of equipment and the industrial pollution,have already been phased out.The strongly acidic cationic exchange resin NKC-9 has been selected as catalyst and part of basic research is finished by the previous research work of our laboratory.But in this process one-way conversion and selectivity of reaction is low,these factors limit the economic efficiency.In order to improve the economic benefits of the process,the direct hydration process of dihydromyrene was studied.The detailed research contents of this thess are as follows:(1)The structure of raw material and products were studied by using GC/MS.The changes of concentration of every component in the hydration process were measured.A reaction scheme contains a side reaction was established,which provide the foundation for the establishment of the reaction kinetics model.(2)The hydration reaction kinetics of dihydromyrene was studied in a batch autoclave reactor with the catalyst of NKC-9 and the solvent of acetone.The effects of reaction temperature,the ratio of raw materials and catalyst concentration on the direct hydration of dihydromyrene were studied under the elimination of the effects of internal and external mass-transfer resistances.The experimental data were fitted with the pseudo homogeneous kinetic model.And the kinetics model for direct hydration reaction of dihydromyrene was established to fit the dynamic data.The calculated values and the experimental values were compared,which showed that the kinetic equation could preferably describe the reaction under the condition of a homogeneous phase reaction liquid.The result shows that the established dynamic model can accurately describe the direct hydration of dihydromyrene under the condition of solid-liquid two phases.(3)The optimum process conditions of the direct hydration of dihydromyrene were investigated in a batch reator and a fixed bed reactor,respectively.The optimal conditions in a batch reactor were temperature 90℃,reaction pressuer 0.8 MPa,agitation speed 600 rpm,catalyst mass fraction 15%,quality ratio of dihydromyrene to water to acetone 1:9:15 and reaction time 5 h,where the conversion of dihydromyrene was 52.29%and the yield of dihydromyrcenol was 43.82%.The optimal conditions in a fixed bed reactor were temperature 90℃,reaction pressuer 0.8MPa,residence time 80 min,and quality ratio of dihydromyrene to water to acetone 1:9:15,where the conversion of dihydromyrene was 52.70%and the yield of dihydromyrcenol was 46.22%.