Design And Control Of The Transesterification Process For Methyl Acetate And N-Butanol Extracted And Catalyzed By Ionic Liquids

In recent years, ionic liquids which have many excellent properties as novel extrainer and catalyst, especially in the energy saving advantages, aroused widespread concerning. First, ionic liquids can be used to eliminate azeotropic mixture in the reactive distillation due to non-ideal equilibrium of different compounds. Second, many ionic liquids can be used as a catalyst in chemical reactions.Cai Jalin etc.(Ind. Eng. Chem. Res.2011,50) recently discussed a simulation for transesterification of methyl acetate and n-butanol in a reactive and extractive distillation column using ionic liquids. Targeted at the lowest TAC, we explored the distillation column pressure, distillation plate number and feed location, and economically optimized the structure of the distillation column. The results showed that the minimum TAC can be obtained at the column pressure of0.8atm, the number of trays of37, and the butanol and methyl acetate feed trays of10and35, respectively. The new designed process can save24.4%cost than the previous work, while the methanol and butyl acetate product purity remained above97.4%and99.6%. This work provides valuable theoretical basis for the energy optimization of actual reaction process. Further, based on actual transesterification production process of methyl acetate and butanol, the design of reactive distillation processes with ionic liquids as the extrainer and the catalyst and the control strategy to overcome the disturbances are developed. Two step disturbances for testing the system controlling performance each is the±20%feed flow rate disturbance and the other is the the5%feed step composition disturbance. Loop simulation results show that the purity of the product MEOH is maintained at molar fraction of99%±0.11%and the purity of the product BUAC is maintained at molar fraction of99.4%±0.12%. The results prove the feasibility and controllability of methyl acetate and butanol transesterification with ionic liquids as the extrainer and the catalyst, and the control strategy can maintain operation stability and good product quality in face of the large flow rate and composition disturbances.