Temperature gradient operation of a simulated moving bed unit

The simulated moving bed (SMB) technology has shown great potential for fin e chemical separations, particularly for the resolution of the enantiomers of chiral compounds. Further improvements of separation performance are exp ected when each section of the unit is optimized independently by applying a gradient of temperature, pressure, or solvent composition along the unit. The aim of this work is to extend the design criteria for nonlinear SMBs t o the case where a temperature gradient mode is adopted. It is shown how be neficial this can be in terms of productivity and solvent consumption. Fina lly, the temperature transient in the columns is studied. It is shown that temperature changes in the column of the unit yield a constraint on the max imum fluid velocity. This is analogous to the constraints due to column eff iciency and packing stability requirements. The results show that the tempe rature gradient operation of an SMB unit is feasible and may have significa nt advantages over the traditional isothermal mode.