Optimization of throughput and desorbent consumption in simulated moving-bed chromatography for paclitaxel purification

In simulated moving-bed (SMB) applications, throughput and desorbent consum ption are two key factors that control process cost. For a given adsorbent volume and product purity requirements, throughput and desorbent consumptio n depend on desorbent composition, column configuration, column length to d iameter ratio, and adsorbent particle size. In this study, these design par ameters are systematically examined for paclitaxel purification. The result s show that if adsorbent particle size, column dimensions and column config uration are fixed, the higher the product purity required, the lower the th roughput. If product purity and yield are fixed, the larger the solute migr ation speed ratio, the higher the throughput, and the lower the desorbent c onsumption. If total bed volume and product purities are fixed, the longer the separation zones, the higher the throughput, but the higher the desorbe nt flow-rate. An intermediate configuration gives the minimum desorbent con sumption. If there are no limits on pressure drop or zone flow-rate, the la rger the column length to diameter ratio, the smaller the adsorbent particl e size, the higher the throughput, and the lower the desorbent consumption. If the maximum zone flow-rate is controlled by the pressure drop limit and not by the standing waves requirement, the longer the columns, the lower t he zone flow-rates and the lower the throughput. For 150-mu m adsorbent par ticles and a maximum zone flow-rate of 300 ml/min, a design with optimal th roughput and desorbent consumption is found for paclitaxel purification. (C ) 1999 Elsevier Science B.V. All rights reserved.