Reactive Distillation

Reactive distillation processes couple chemical reactions and physical separations into a single unit operation. The combination of reaction and separation within a single unit operation not only reduces the overall capital cost of a process but also provides process benefits in some cases. These benefits arise from the continuous recycling of reactants to the reaction zone which increases the conversion of the limiting reactant in an equilibrium reaction. A secondary benefit is the increased energy efficiency which results from direct utilization of heat of reaction for fractionation. These processes as a whole are not a new concept as the first patent dates back to the 1920s. It can be utilized for both equilibrium and non-equilibrium (irreversible) reactions. In the first case, the withdrawal of products, as they are formed, results in an increased conversion that can be achieved. This increase is achieved through a shift in the equilibrium, based on Le Chatelier’s principle. In the second case, it is generally applied to the systems where products may react with the reactants, causing a decrease in product yield in conventional reactors.