Geometric methods provide a useful framework for assessing the process opportunities of combining reaction and separation. The attainable region can be used to estimate the incentive for developing process technology based on single-stage, and multi-stage vapor-liquid reactors. In some instances, this may lead to process alternatives based on RD.

A flash cascade model is developed to estimate feasible products from a continuous single-feed RD column. An important finding is that the fixed point structures for the rectifying and stripping cascades are different for the kinetically controlled regime. The fixed point structure of the flash cascade model is helpful in determining the reaction regime in which the column must be operated to get the desired products. We used a feasibility diagram to depict possible direct and indirect split products as a function of production rate, catalyst level, and liquid holdup. With this diagram one can quickly determine if a desired product can be obtained from a single-feed reactive column.

Feasibility analysis for RD has advanced to the point that useful engineering methods can be implemented relatively easily. Attainable region methods, however, are still relatively new and there remains significant potential for developing a framework to generate process alternatives with combined reaction and separation using this approach. If these methods could be developed further, it should be possible to link attainable region methods to feasibility methods to build a useful design tool (synthesis methodology) for generating and screening process alternatives for multifunctional reactor-separator devices.

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