Residue curves and residue curve maps have been extensively studied for over 100 years. Much of the literature in this field deals with systems that do not react. Chemical reactions can influence residue curve maps in some important ways. For example, it is known that reactions can lead to both the appearance and disappearance of stationary points (azeotropes), and that reactive azeotropes can exist even in systems that otherwise would be considered thermodynamically ideal. It follows that chemical reactions can influence the very existence of separation boundaries and, therefore, the design and synthesis of reactive separation processes.

Lucia & coworkers have shown that distillation boundaries in non-reacting ternary liquid mixtures can be defined as local maxima in the line integral from any unstable node to all reachable stable nodes. In addtion, they have shown that the minimum energy design for a specified separation can be defined by the shortest feasible stripping trajectory (when measured from the bottoms composition to the pinch point). Among other things this approach:

Easily finds minimum energy solutions that do not correspond to separation pinch points.

Is unaffected by the number of components.

Provides knowledge of other solutions that have near minimum energy consumption.

Solves problems other synthesis methodologies cannot.

This paper shows how the geometric approach of Lucia and coworkers can be adapted for the rigorous determination of minimum energy reactive distillation systems. Examples include 4 component systems with a single equilibrium reaction and ternary systems with a kinetically controlled reaction.