New Multicomponent SMB/Chromatographic Separations

Purdue University, West Lafayette IN

Investigators

Abstract

This project is developing a number of improved simulated moving-bed (SMB) systems for both binary and ternary separation problems. Selective partial withdrawal (removal of product during only part of the cycle) and dual product withdrawal (use of two product lines for the same product) are analyzed for both the raffinate and extract streams for 3 and 4-zone SMB systems. Detailed computer simulations are used to optimize flow rates. A number of additional new SMB cascades are being devised in the course of the research. These new cascades are designed to result in better separations while using less or the same amount of desorbent. This research uses detailed simulations to delineate binary separation problems for which the new SMB cascades have lower desorbent use and/or higher productivity than a standard 4-zone SMB while obtaining the same product purities. The most promising candidates are selected for experimental confirmation. Since ternary SMB separations are becoming increasingly important, particularly in the pharmaceutical industry, a number of new ternary SMB cascades are also being examined for both complete separation of the ternary system and for the case where only one product is desired from the ternary feed. SMB cascades for quaternary feeds will also be analyzed. Adsorption simulators are being introduced into graduate-level chemical-engineering courses. Simulated Moving Bed (SMB) adsorption systems have proven to be the most cost effective method for doing large-scale chromatography for binary separations and have been commercialized for a number of separations such as p-xylene purification, separation of fructose and glucose, and, most recently, optical isomer separations. SMB systems are considered to be expensive separation techniques, with costs dominated by desorbent use and productivity. If successful, this research will conclusively prove that desorbent use and productivity can be significantly improved compared to current 4-zone SMB technology. The new cascades being developed for binary separations will significantly increase the productivity without increasing desorbent use, while the new cascades being developed for ternary separations will significantly increase the productivity and decrease desorbent use. These new designs will have a significant impact on the design of SMB systems for industrial separations and hence on product cost.