(442d) Chemical Synthesis with Extractive Product Isolation as An Approach for Process Intensification

Lux, S., Graz University of Technology
Winkler, T., Graz University of Technology
Siebenhofer, M., Graz University of Technology

Chemical synthesis reactions such as esterification reactions may result in extended complexity due to formation of azeotropic mixtures. Stringent efforts for subsequent product isolation are required. Production of methyl acetate is a representative example for formation of highly complex mixtures during reaction. Methyl acetate forms low boiling azeotropic mixtures with the reactant methanol as well as the by-product water. The state-of-the-art process for production of methyl acetate is based on a reactive distillation process, the so called Eastman Kodak process. In principle the Eastman Kodak process is a dual step esterification process with the basic intention of avoiding azeotrope formation by supplying different excess reactant in both reactor sections. In this project technical approaches for production and isolation of methyl acetate below boiling point operation are investigated. The reaction is carried out in a packed bed plug flow reactor. Strongly acidic cation exchange resins are used as heterogeneous catalysts. Formation of the methyl acetate/methanol azeotropic mixture is avoided by metering acetic acid in excess. The azeotropic mixture methyl acetate/water can be overcome through selective extraction of methyl acetate from the multicomponent reaction mixture with consecutive distillative isolation, finally leaving a mixture of acetic acid and water for distillative separation. For technical as well as economic process comparison adsorptive separation of water and methanol from the reaction mixture was investigated too. During esterification the catalyst undergoes swelling in the multicomponent reaction mixture. For modeling purposes the composition and propagation of swelling of the resins was investigated by determining the adsorption characteristics of reactants and products. The project provides basic strategy for process design of esterification processes with the aim of developing new on-site-processes for stock quantities.