Competitive Reaction Kinetics And Conditions Optimization Of Mixed Diol And Propanal

In the production process of coal-based ethylene glycol,the boiling point of1,2-butanediol and ethylene glycol are close,which makes they are difficult to separate,and reducing the yield and purity of ethylene glycol.Our research group has conducted in-depth research on the separation of this azeotrope,and proposed a new separation process,namely,chemical cycle method of propanal acetal for the separation ethylene glycol and 1,2-butanediol.However,the lacked multiple reaction kinetics data is a key factor limiting the industrial application of this process.Therefore,the reaction kinetics of the reaction system was studied using KRD001cation exchange resin as catalyst,and the experiment of fixed bed reactor was carried out.Finally,the reaction process was predicted by combining with Aspen Plus software,and the simulation results were compared and optimized,so as to be better used in the process of separating ethylene glycol and 1,2-butanediol by chemical cycle method of propionaldehyde acetal.First,the kinetics of reaction between ethylene glycol and propanal,1,2-butanediol and propanal,1,2-butanediol and 2-ethyl-1,3-dioxolane was studied in batch reactor using KRD001 cation exchange resin as catalyst.After eliminating the influence of internal and external diffusion,the effects of catalyst dosage,temperature,molar ratio of reactants on reaction rate and conversion rate were explored,and got the reaction heat of the three reactions.On this basis,a quasi-homogeneous reaction kinetic model was established,and the kinetic equations of the reactions of propanal and ethylene glycol,propanal and 1,2-butanediol,1,2-butanediol and2-ethyl-1,3-dioxyamyl ring were obtained by MATLAB regression experimental data.Subsequently,in a fixed bed reactor the experiment of competitive acetal reaction between ethylene glycol,1,2-butanediol and propanal was carried out to investigate the effect of reaction temperature,space velocity and feed molar ratio on the selectivity of competitive reaction.It was also found that reasonable control of the amount of propanal can achieve the difference in the conversion rate of ethylene glycol and 1,2-butanediol,that is,propanal reacts with ethylene glycol and1,2-butanediol with the highest selectivity difference.Finally,using the Aspen Plus software plug flow reactor model,and combined with the reaction kinetics data of chapter 2 to simulate the reaction of ethylene glycol,1,2-butanediol and propanal in a fixed bed reactor,and optimize the reaction conditions.Then the accuracy of the model was verified by comparing with the experimental data in fixed bed reactor,and the validated model was used to further optimize the reaction conditions.It can be concluded that when the molar ratio of Prop and EG is 0.4,the space velocity is 0.50h^-1 and the reaction temperature is 10℃,the RSD value reaches the minimum value of 0.3316.Finally the maximum selectivity difference between propanal,ethylene glycol and 1,2-butanediol was realized,and the results provided basic data for the process design of separating ethylene glycol and 1,2-butanediol by chemical cycle method of propanal acetal.