In reactive distillation (RD), one or more feeds can be used, and the reactive zone can be anywhere in the column and depending on the product, it may exit from either the overhead or bottom. Enhancement in conversion, selectivity, energy utilization, reduction in equipment cost and separation of otherwise difficult toseparate mixtures are some of the motives behind its several applications. ] Today, RD is used mainly for etherification and Esterifications reactions, but it has also been successfully applied to alkylation and nitration reactions. Most early applications involved liquidphase reactions; and if a catalyst was utilized, it was in solution. In more recent applications, solid catalysts had been used. An example is the production of methyl-tert-butyl-ether (MTBE), an an additional entrainer. For example, in the case of ethanol-water mixture (azeotropic composition 89.4 mole% at 101.325 kPa), an azeotrope does not form below a pressure of approximately 9.2 kPa. Pressure-swing distillation is a method for separating a pressure-sensitive azeotrope that utilizes two columns operated in sequence at two different pressures.