New Process Development And Design Of Synthesizing Solketal By Reactive Distillation Dividing-wall Technology

Solketal（2,2-dimethyl-1,3-dioxolane-4-methanol）is an important intermediate for organic synthesis which is widely used in food,medical and other fields.In order to solve the disadvantages of traditional synthesis process for solketal production with low single-conversion,high investment in production equipment,long post-treatment process,large energy consumption and environmental pollution,this paper proposes an energy efficient process,reactive distillation dividing-wall column（RDWC）.This paper combined the pilot experiments and simulations,systematic research were carried out on the reactive distillation（RD）and the novel reactive distillation dividing-wall process by using glycerol（G）and acetone（Ac）to synthesize solketal（SK）.Firstly,the kinetics of the ketalization reaction catalyzed by the cationic resin catalyst NKC-9 was studied in a batch reactor,which provided basic data for subsequent reactive distillation experiments and simulations.Under the condition of eliminating internal and external diffusion,the effects of catalyst loading,temperature and molar ratio of acetone-glycerol on the conversion rate were investigated.A Langmuir–Hinshelwood–Hougen–Watson（LHHW）model was established and the kinetic parameters of the reaction were calculated by MATLAB.Secondly,in a self-built reactive distillation column,seven experiments were carried out using the NKC-9 catalyst and packing the seepage catalytic packing internal（SCPI）andθring packing to study the effects of reflux ratio,operating pressure,feed molar ratio and feed type on the RD process.The feasibility of RD process in this reaction system was also verified.The SK purity of 99.5wt%that meets the industry requirements was successfully obtained through batch distillation experiments.Based on the basic data of kinetics and thermodynamics obtained from the research,the process simulation software was used to establish the strict mathematical model of RD,and the reliability of the model was verified by the comparison of simulation data and experimental results.Through sensitivity analysis,the effects of parameters such as feed molar ratio,feed position,operating pressure,reflux ratio,the number of the theoretical stages in the reaction zone,rectification section and stripping section on the conversion and energy consumption per unit mass were explored.A mathematical model of the acetone recovery column was established,the effects of the feed position,the number of theoretical stages and the reflux ratio were investigated.The results showed that>99.5wt%of acetone could be recycled with relatively less energy consumption.Finally,for the entire production process,the model of RDWC was established,the influence of key parameters such as the liquid split ratio,reflux ratio and the theoretical number of the stages on the conversion,the purity of SK in bottom stream,the energy consumption per unit mass and the total annual cost（TAC）were determined.The comparison between the RD and RDWC processes showed that when completing the production process of SK with the same requirement,by RDWC the energy consumption has been saved by 20.6%,the TAC has been reduced by18.3%,and CO₂ emissions have been reduced depending on the type of fuel（13.3%,15.7%and 28.9%as natural gas,oil resources and coal resources,respectively）.The research results can provide basis and reference for the design of solketal industrial production.