Molecular Simulation Of Propylene Chlorination Reaction Kinetics At High Temperature And CFD Simulation And Optimization Of The Reactor

Allyl chloride reaction is one of the most important reactions in chemical production.Under the condition of high temperature, without catalyst, propylene and chlorine gas can happen substitution, addition reaction, etc. Among them, not only has to generate 3-allyl chloride of the main reaction, also with a variety of adverse events, product composition is very complicated. Main product of 3-allyl chloride is a very important chemical intermediates and raw material, has a very wide range of use, and is commonly used in organic synthesis、spices、adhesives、pesticides、paint, also used in synthetic resin and plastics flame retardant,etc. But at present industrial production of acrylic high temperature chlorination usually appears short driving cycle、the low yield、high energy consumption、more by-products and so on.Staring from the chlorination reaction source, this paper tries to provide technical support to solve the above problems through in depth to explore the molecular mechanism of chlorination reaction and chlorination reactor structure optimization design. In general, this paper is divided into two parts:The first part is the molecular simulation of the propylene high temperature chlorination reaction. The paper puts forward three reaction mechanisms under high temperature in this part. The three reactions are chlorine gas and propylene to generate 3-allyl chloride and hydrochloric acid（Cl₂+C₃H₆�'3-C₃H₅Cl+HCl）, chlorine gas and propylene to generate1,2-dichloro propane（Cl₂+C₃H₆�'1,2-C₃H₆Cl₂） and chlorine gas and 3-allyl chloride to generate 2,3-dichloro propylene and hydrochloric acid（Cl₂+3-C₃H₅Cl�'2,3-C₃H₄Cl₂+HCl）. In the MP2/6-31 G theoretical level, the paper searches for the transition states in their most possible reaction path. Finally, the paper obtains three macroscopic kinetic models of the three reactions. The above three reactions are in turn called reaction I、reaction II and reaction III.The results and conclusions of the molecular simulation:（1） The reaction mechanism of acrylic high temperature chlorination is the free radical mechanism and has the rate-determining step（2） This paper determines the three rate-determining steps and the reaction activation energies according to the primitive reaction, and the reaction activation energies of the three rate-determining steps are 78.42 k J/mol、27.83 k J/mol and 148.87 k J/mol,respectively.（3） The reaction rate constants of the three rate-determining steps are followed by k（1-2）=1.94×10⁷×exp（（-71.29×1000）÷8.314T） k（2-3）=4.61×10⁶×exp（（-3.9.26×1000）÷8.314T） k（3-2）=7.01×10⁷×exp（（-143.08×1000）÷8.314T） （4） Through the analysis of the macroscopic kinetics of the three reactions, it is concluded that the low temperature is advantageous to the addition reaction, and the high temperature is advantageous to the substitution reaction. The macroscopic kinetic equations of the three reactions are r₁=3.61×10⁹×exp（（-113.98×1000）÷8.314T）(Cl_2<sup>1/2（CH₂CHCH₃） r₂1=3.61×10³×exp（（-70.52×1000）÷8.314T）(Cl_2<sup>3/2（CH₂CHCH₃） r₃=2.2.8×10¹⁰×exp（（-185.77×1000）÷8.314T）(Cl_2<sup>1/2（CH₂CHCH₂Cl）The second part is the numerical simulation and optimization of the jet mixing reactor.Based on the macroscopic kinetic models, this part optimizes the propylene high temperature chlorination reactor by means of CFD numerical simulation method. The main aspects of jet mixing reactor optimization include the throat radius, mixing length, mixing angle, C₃H₆/Cl₂ inlet molar ratio and C₃H₆ inlet temperature. Through the investigation of the influence of above five aspects on the temperature distribution and the product distribution of the jet mixing reactor, this part obtains a group of optimized data. The results and conclusions of the second part:（1） The CFD numerical simulation results of the reactor are consistent with the results obtained from the actual industrial production;（2） Based on the numerical simulation analysis of a series of throat radius、mixing length and mixing angle、C₃H₆/Cl₂ inlet molar ratios and C₃H₆ inlet temperatures, the reactor is most advantageous to production of3-C₃H₅ Cl when the throat radius is 50 mm, the mixing length is 150 mm and the mixing angle is 30°, C₃H₆/Cl₂ inlet molar ratio is 5.4:1 and C₃H₆ inlet temperature is 613.15 K.