Introduction to Continuous (SMB) Chromatography
Simulated moving bed chromatography (SMBC) was invented in the 1950’s by Broughton and colleagues at UOP for large-scale separation of n-paraffins, and is used today in many variations in the petrochemical, food, and pharmaceutical industries. The SMBC process has made liquid chromatography economically feasible on an industrial scale due to its high productivity relative to batch (single-column) methods. This enhanced productivity (up to 20-fold) is achieved through much more efficient utilization of the solid and liquid phases required for separation. In simplest terms, SMBC does more with less.
The basic concept of simulated moving bed chromatography is to use multiple smaller columns containing the solid adsorbent (beds) rather than one large column, and to “move” the beds in the opposite direction of the fluid to achieve a countercurrent flow, rather than flowing fluids through one static bed. The “simulated movement” is typically carried out through multiport valves interspersed between the columns, such that the input and output fluid streams can be periodically switched from column to column in the direction of fluid flow. Rather than applying feed and desorbent and collecting fractions sequentially with one column, all fluid streams are simultaneously applied and withdrawn at appropriate points between the columns. When running at a steady state, the various stages of separation are carried out simultaneously by different columns in a continuous cycle.
For more information and to visualize the principles of simulated moving bed chromatography please see the “Introduction to SMBC” (11:35 min) and “What is SMBC?” (coming soon) videos on this page.
Benefits of SMBC
The countercurrent ﬂow created by SMBC enables extremely efficient utilization of solid and liquid phases. In single-column systems, separation actually occurs in a small portion of the column at any one time, with the rest of the column performing no function other than occupying solvent and broadening bands. With SMBC, typically 50-70% of the solid phase is engaged in the separation zone, while the rest of the adsorbent material is being prepared for the next cycle of separation. Moreover, SMBC provides essentially an “infinite” column bed length without the costs associated with obtaining, operating, and maintaining large single columns.
- Higher recovery and purity
- Lower solvent consumption
- Higher productivity – up to 20-fold vs. batch systems
- Larger stationary phase particles, lower pressures
- Scalable from milligrams to tons of purified product
- Continuous process
- Bulk separations
- End product purifications
- Impurity analysis
- Chiral separation
- Process development
- mAbs, recombinant proteins
- Natural products
- Sugars, sugar alcohols
- Amino acids
- Organic acids
- Fatty acids