Kinetics And Equipment For The Production Of Azelaic Acid By Oxidative Cracking Of Oleic Acid

Azelaic acid is an important fine chemical intermediate,generally manufactured by ozonolysis of oleic acid.This process has many advantages including mild conditions,good selectivity,high yield,no pollution,etc.This process consists of two reaction steps:oleic acid first ozonizing to ozonides by ozone,then,ozonides was decomposed to azelaic acid and pelargonic acid by oxygen.Two reactions belong to the gas-liquid mass transfer reaction,often using stirring bubble reactor with batch operation.In order to realize continuous production of azelaic acid,a new gas-liquid reactor "rotor drum reactor" was developed by our research group,and preliminary researches focus on hydrodynamics and mass transfer performance for the rotor drum reactor.However,there are still two key issues requiring further study for better designing the rotor drum reactor for the production of azelaic acid,including the kinetics of two gas-liquid mass transfer reactions,determination of critical operating parameters like gas-liquid interfacial area in rotor drum reactor.In view of the above two issues,the main contents as well as the conclusions consist of the following two parts:(1)The kinetics of two gas-liquid mass transfer reactions for the production of azelaic acid were studied in a double-stirred reactor,respectively.Results showed that two reactions were pseudo-first reactions;in case of first reaction step,the second-order rate constant k2 was 2.32×104 m~3·kmol-1·s-1 at 32 ℃,the correlation equation for the enhancement factor E and oleic acid concentration in liquid phase CBL1/2 listed as follows:E =402.7·CBL1/2(correlation coefficients R~2=0.98);in case of second reaction step,k2 was 2.06×104 m~3·kmol-1·s-1 at 90℃,E = 346.6-CBL1/2(correlation coefficients R~2=0.95).(2)The gas-liquid interfacial area in a rotor drum reactor was measured by chemical method,the effects of high-gravity factor of drum surface,gas flux and liquid flux on the interfacial area in the rotor drum reactor were investigated,respectively.Results showed that the interfacial surface increased with the increase of high-gravity factor and liquid flux initially,and then tended to be smooth.The gas-liquid interfacial area in the rotor drum reactor existed a maximum value with the increase of the gas flux.The maximum gas-liquid interfacial area of 0.058 m~2 was obtained when the high-gravity ’factor of the drum surface,gas flux and liquid flux were 5,77m~3/(m~2·h)and 398 m~3/(m~2·h),respectively,and the corresponding interfacial surface per volume was 137(m~2/m~3).