Chemical processing routes based on reaction pathways

Abstract

The integration of reaction and separation tasks in one process unit represents a potential advantage for overcoming reaction limitations, such as reaction equilibrium. The design of reactive separation units based on specific reactions has been widely discussed in the literature. However, few approaches have been made towards the systematic generation, evaluation and analysis of reactive separation configurations in the early stage of process synthesis. Reactions limited by chemical equilibrium are common in the industry and it is known that, from the definition of the equilibrium constant, the amount of product that is produced through a reversible reaction can be increased by continuously removing one of the reaction products from the reactor. The fast evaluation of alternatives in process synthesis is done with simple models. However, for the consideration of reactive separation of equilibrium-limited reactions, modeling of reaction kinetics, reaction equilibrium and phase equilibrium needs to be considered: it is important to set up simple yet reliable models. A systematic method has been developed to analyze and evaluate alternative reaction-separation configurations based on phase equilibrium. The step-by-step procedure for the problem formulation and solution is given in terms of a workflow consisting of nine steps. A generic simple model for reaction-separation units has been set up and its use throughout the workflow has been defined. In addition, supporting methods and tools have been described, including algorithms, a knowledge base and software tools. Esterification reactions are used as case studies to show the method application due to their characteristics: the interest of their products, their equilibrium limitation, and the characteristics of their phase equilibrium (azeotropes and liquid phase split).