The improvement of simulated-moving-bed chromatography (SMB) performance through variation of parameters during a switching interval is pushing the trend towards the use of units with smaller number of columns, since less stationary phase is used and the setup is more economic. This includes, among others, the non-synchronous shift of the inlet and outlet ports within a global switching period, modulation of solvent strength during process operation, and cyclic modulation of feed flow and feed concentration.

In the present work we demonstrate that eluent consumption for optimized asynchronous configurations in the higher feed-throughput region can be significantly reduced by modulation of eluent flow rate and selective product withdrawal.

The model system selected to demonstrate the feasibility of this new hybrid operation scheme is the separation of binaphthol enantiomers on cellulose tris-(3,5-dimethylphenylcarbamate) using isopropanol as eluent, with linear and competitive nonlinear isotherms.