CALCULATION OF RESIDUE CURVE MAPS FOR MIXTURE WITH MULTIPLE EQUILIBRIUM CHEMICAL-REACTIONS

We derive the differential equations governing the simple distillation of mixtures with multiple equilibrium chemical reactions. The results are most conveniently expressed in terms of transformed composition c oordinates, which provide a reduction of dimensionality consistent wit h the Gibbs phase rule. The resulting residue curve maps give an easy visualization of the combined phase and chemical equilibria, and from them it is possible to determine the presence of reactive azeotropes, as well as nonreactive azeotropes that survive the reactions. Three ex amples are described: an ideal mixture based on the chemistry of forma ldehyde + water, the synthesis of MTBE in the presence of inert n-buta ne, and the alkylation of m-xylene in the presence of inert p-xylene.