Solvent gradient operation of simulated moving beds. I. Linear isotherms.

Area of Science:

• Chemical Engineering
• Chromatography
• Separation Science

Background:

• Simulated Moving Bed (SMB) chromatography offers continuous separation with high productivity and low solvent use.
• Current SMB processes typically operate under isocratic conditions, limiting potential performance gains.
• Gradient elution strategies can optimize solute retention and improve separation performance.

Purpose of the Study:

• To investigate the application of a solvent gradient in a closed-loop SMB unit.
• To extend equilibrium theory design criteria for non-linear SMBs to gradient operation.
• To compare the solvent gradient mode with the isocratic mode regarding productivity and solvent consumption.

Main Methods:

• Utilizing solvent mixtures with two different compositions at the feed and desorbent inlets.
• Establishing distinct mobile phase compositions in different sections of the SMB unit.
• Extending equilibrium theory design criteria to derive the separation region and optimal operating conditions for gradient SMB.

Main Results:

• The solvent gradient mode allows for tuning solute retention along the SMB unit by varying mobile phase composition.
• The study provides a framework for deriving the separation region and identifying optimal operating conditions in gradient SMB.
• The solvent gradient mode demonstrated potential for enhanced productivity and reduced solvent consumption compared to isocratic SMB.

Conclusions:

• Solvent gradient elution is a viable strategy to improve SMB separation performance.
• The extended equilibrium theory provides a robust method for designing and optimizing gradient SMB processes.
• Gradient SMB offers a promising approach for efficient and sustainable separations in fine chemistry.