Multi-objective optimization of sequential simulated moving bed for the purification of xylo-oligosaccharides

This paper investigates feasibility of xylo-oligosaccharides (XOS) purification by sequential simulated moving bed (SSMB) that has three sub-steps. Multi-objective optimizations were carried out for three cases with various objective functions, decision variables and constraints. It was found that, for a given SSMB unit, there exist a Pareto curve when product purity and unit throughput are simultaneously maximized with practical constraint on recovery. The corresponding values of flowrate ratio, however, exhibit some trends different from those of conventional Simulated Moving Bed (SMB). Analyses on component mass flow and dimensional operating parameters reveal that these differences can be attributed to the fact that the three sub-steps with different durations and flow patterns have their individual functional roles. Pareto solutions to several other optimization problems with solvent consumption as one of the objectives were acquired. The corresponding flow rate ratios are not enough to give qualitative guidance for tuning the dimensional operating parameters. (C) 2019 Elsevier Ltd. All rights reserved.