Research On The Acetylation Of Camphene To Isobornyl Acetate By Oscillatory Flow Reactor

Acetylation of camphene to isobornyl acetate is the key step in camphor synthesis using a-pinene as starting material.This reaction is strongly exothermic and ununiformed temperature distribution in the reactor will result in a high by-product concentration in the product.In addition,cation exchange resin as catalyst for this reaction will easily deactivate because of the overlay of polymer byproducts on the resin surface.In industry,batch reactor or fixed bed reactor is adopted to produce the isobornyl acetate conventionally,but the problems of uneven temperature distribution,high concentrations of by-product and quick catalyst deactivation have not been resolved so far.A kind of novel reactor,oscillatory flow reactor(OFR),was used to solve the problems mentioned above.OFR can improve the mixing degree of material significantly,has good perfomance of mass and heat transfer,shows plug flow characteristics under the continous operation,and can easily been controlled in the production process.Lots of basic research and applied research of single phae system in OFR have been published,however only few studies about heterogeneous system were reported.The residence time distribution and heat transfer of solid-liquid system in OFR were studied firstly in this paper,and on this basis the continuous production of acetylation of camphene to isobornyl acetate by OFR was realized.The specific results of the experiments are as follows:(1)The influence of net flow velocity,oscillatory amplitude,oscillatory frequency and volume fraction of solid particles on the residence time distribution was studied,and the modeling parameter N of the tanks-in-series model was used to evaluate the residence time distribution.The results show that N increased with the increasing net flow velocity and smaller intensity of oscillatory flow,which tend to plug flow.Furthermore,the addition of solid particles made the system more complex and the fluid flow was blocked and the back mixing was more serious,which resulted in a deviation from the plug flow.(2)The influence of net flow velocity,oscillatory amplitude,oscillatory frequency and volume fraction of solid particles on the heat transfer was discussed,and the dimensionless number,Nusselt number,was used to estimate the heat transfer effect.The results show that Nusselt number increased with the increasing net flow velocity,and it increased first then decrease and stabilize finally with the velocity ratio,?,when ?=3 the peak value of Nusselt number appeared.The addition of solid particles had a counter effect on the heat transfer when the intensity of oscillatory flow maintained at a low level(2654<Reo<10244).But if the intensity of oscillatory flow situated at a high level(12821<Reo<18527),there is no distinction of the heat transfer between solid-liquid system and single liquid system.Because at this moment the solid particles performed some fluid-like characteristics,and in this case,the impact of the solid particles was not so obvious.(3)On the basis of the above studies,the experiments of continuous synthesis of isobornyl acetate in the OFR with camphene and acetic acid as raw materials were conducted.The results show that the OFR can control the temperature distribution and catalyst distribution more evenly.The conversion and selectivity of OFR process were both superior to a batch process.In addition,in the OFR process the catalyst surface was constantly renewed under the oscillation,so little polymer covered catalyst surface,which prevent catalyst from quick deactivation.The residence time distribution and heat transfer of the solid-liquid system in OFR were investigated in this thesis,and the application of OFR to the acetylation of camphene was realized for the first time,which laid a solid foundation for the application of OFR to other areas.