Selectivity engineering with single-feed hybrid reactive distillation columns

Abstract

Reactive distillation (RD) can be advantageously used to improve the selectivity of the desired product in the multi-reaction system. Process synthesis and design of RD systems to attain the desired selectivity is a challenging task. Our previous work in this field (e.g. Amte et al., 2011, 2012) was restricted to fully reactive RD models and their networks. In this work, we examine the potential of a hybrid reactive distillation column, with both reactive and non-reactive sections, through an example of a single reactant complex reaction scheme (e.g. van de Vusse reaction) in which reactant is intermediate boiling. An algorithm for conceptual design of such columns is presented. It is based on the boundary value method (BVM) that utilizes the concept of operation leaves of rectifying and stripping sections; the overlap of which indicates the potential feasible split. Based on the desired selectivity, we determine the locus of reactive stage compositions in the RD column. Its intersections with the non-reactive stage composition lines (SCL) allow rapid screening of feasible designs of hybrid reactive distillation (HRD) columns. The approach generates multiple designs and allows one to compare them in terms of energy and catalyst requirement. The proposed method is applicable to single reactant single-feed hybrid columns, and because of its graphical representation, it cannot be directly used for systems with a large number of components. More work is therefore necessary to extend this approach to the multi-reactant double-feed hybrid configurations.