Ultimate Reaction Selectivity Limits for Intensified Reactor–Separators

Abstract

The Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison, proves that any and every reaction/mixing/separation process is equivalent to a process comprising at most +1 CFSTRs and a perfect mixer−separator, where is the number of linearly independent chemical reactions. Frumkin and Doherty showed that the CFSTR Equivalence Principle can be used together with global optimization to find the maximum selectivity of a chemistry independent of process design. These selectivity targets are useful in the context of process intensification because they represent ultimate selectivity improvements that can be achieved by combining multiple unit operations into a single device. In this work, the model is reformulated as a mixed-integer nonlinear program to solve this nonlinear and nonconvex optimization problem. We implement a more robust, deterministic global optimization using a spatial branch-and-bound algorithm (BARON) to investigate the selectivity limits for production on acrolein, a chemistry that has 13 components and 17 reactions. We find maximum selectivities that are lower than the stoichiometric selectivity limit and can be used as a target for process intensification. Article pubs.acs.org/IECR

Accounting for costs in attainable‐region‐based reactor–separation network synthesis: Models, tradeoffs, and insights

“…To improve the solution time of the model, we add the following redundant mass balances, 37 where is the total extent of reaction and is the set of reference components , which must be chosen such that the stoichiometric matrix containing only these components is invertible. Note that .…”

Toward an Envelope of Design Solutions for Combined/Intensified Reaction/Separation Systems

“…We characterize the design space under a certain production task in accordance to the FD theory. , Since the pentene metathesis reaction takes place in the liquid phase at fixed atmospheric pressure, the available design parameters are reaction temperature ( T ) and reactive volume ( V ). Reaction kinetics for this chemistry are valid between 277.15 and 340.15 K, which provide the largest feasible temperature range.…”

“…Hereafter, we will refer to this approach as “Feinberg Decomposition (FD)”. Frumkin and Doherty − further extended the FD approach to characterize selectivity bounds in RMS systems. Despite the indispensable boundary information given by the CFSTR principle, this approach cannot generate correspondingly candidate process alternatives at, or within, the derived bounds.…”

Preface for Special Issue on Frameworks for Process Intensification and Modularization

“…A contribution in this direction comes from Doherty et al, who identify the limits of reaction selectivity that can be used as a target for process intensification using a reactor−separator. 24 While synthesis-guided intensification provides promising intensification pathways and candidate flowsheets, it is also important to ensure the operability, controllability, safety, and flexibility of these new designs. These encapsulate a broader scope of process systems engineering (PSE) methodologies toward realizing the full potential of intensified process systems.…”

“…Even before one embarks on designing intensified processes, it is important to know the extent to which intensification can help improve a process. A contribution in this direction comes from Doherty et al, who identify the limits of reaction selectivity that can be used as a target for process intensification using a reactor–separator …”