Determining SMB Superstructures by Mixed-Integer Optimal Control

We treat a simplified model of a Simulated Moving Bed (SMB) chromatographic separation process that contains time-dependent discrete decisions. SMB processes have been gaining increased attention lately, see [3], [4] for further references. The related optimization problems are challenging from a mathematical point of view, as they combine periodic nonlinear optimal control problems in partial differential equations (PDE) with time-dependent discrete decisions. For this problem class of mixed-integer optimal control problems (MIOCP) a novel numerical method, developed in [5], is applied.