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Synthesis of ETBE: Residue curve maps for the heterogeneously catalysed reactive distillation process

1997; Elsevier BV; Volume: 66; Issue: 3 Linguagem: Inglês

10.1016/s1385-8947(96)03173-7

1873-3212

Christian T. Thiel, Kai Sundmacher, Ulrich Hoffmann,

Phase Equilibria and Thermodynamics

The liquid phase synthesis of octane-enhancing ethers is increasingly realized as a reactive distillation process, catalysed by ion exchange resins. To study the physical and chemical phenomena occurring in these systems, the present paper considers a reactive batch distillation process in a heated still. Because of its increasing technical importance, the synthesis of ETBE (ethyl tertiary butyl ether) from ethanol and isobutene is investigated as an example. The developed model is based on the phase equilibrium between the liquid and vapour phases and an adequate kinetic formulation of the heterogeneously catalysed etherification by application of generalized Langmuir-Hinshelwood rate expressions. To describe the non-ideal mixture behaviour, the liquid phase activities are introduced. Simulation results show that the shape of the residue curves depends on two essential parameters: the Damköhler number, Da, and the operating pressure, p. The values of these parameters influence the existence and the position of fixed points in the residue curve map. Therefore an analysis is carried out to calculate the steady state solutions in the reactive mixture and to forecast the number of stable nodes with given Da and p.