Purification And Production Of Azelaic Acid By Oxidative Cracking Of Oleic Acid In The Rotor Drum Reactor

Azelaic acid is an important fine chemical intermediate, mainly used for the production of DOZ, perfumes, lubricants, oils, polyamide resin, and etc. Azelaic acid is often prepared by ozonolysis of oleic acid in an industrial scale, which has many advantages, such as good selectivity, mild reacting conditions, high yield, no pollution, and etc. This process consists of two steps:firstly, oleic acid was ozonized to ozonides by ozone, then, ozonides was decomposed to azelaic acid and pelargonic acid by oxygen. Two reaction steps 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 comprehensive studies have been conducted, such as hydrodynamics, mass transfer performance and gas-liquid interfacial area for the rotor drum reactor. Based on the preliminary researches, in this paper, gas-liquid mass transfer and reaction characteristic for the continuous production of azelaic acid by ozonolysis of oleic acid in rotor-drum reactor was systematically investigated, a rate model was developed for both reaction steps. In addition, the purified process for azelaic acid by the extraction of hot water was also investigated. The main content as well as the achieved conclusions is as follows: (1) The effects of rotation speed, liquid flow rate and gas flow rate on the reaction rate in the rotor drum reactor were investigated for the production of azelaic acid by ozonolysis of oleic acid, respectively. Result showed that the reaction rates for both reaction steps increases with the increase of rotation speed and liquid flow rate initially, and then tends to be smooth. The reaction rates in the rotating drum reactor exists a maximum value with the increase of the gas flow rate. The maximum reaction rate can be obtained when the rotation speed, liquid flow rate and gas flow rate are1699r/min,45ml/min and3L/min, respectively.(2)Using Onda model, the gas phase transfer coefficient and liquid phase transfer coefficient were calculated. Based on film theory, a gas-liquid mass transfer and reaction model was developed to predict the two-step reaction rate in rotor drum reactor. Model value has a good agreement with the experimental results.(3)According to the L9(34) orthogonal form, the effect of four operating factors (including phase ratio, extraction time, extraction temperature, extraction times) on the yield of azelaic acid extracted by hot water were investigated under three levels. Result showed that the maximum yield of azelaic acid of34.5%can be obtained when the phase ratio, extraction time, extraction temperature and extraction times are1:8,30min,90℃and three times, respectively, the corresponding purity can stablely achieve at81.41%.