Stricter regulations from the regulatory agencies (FDA, EMEA) and growing environmental concerns force pharmaceutical, agrochemical and food industries to need even purer products. Moreover, the development of purer products with improved biological/pharmaceutical activity allows the extension of existing patents, providing the companies with a longer time for their exploitation.
Preparative chromatography has been playing an important role as a separation and purification process in these industries wherever classical techniques such as distillation are not feasible. A remarkable breakthrough has been achieved by the development of continuous simulated moving bed (SMB) chromatography for fine chemical separations, which allows to achieve significant advantages over batch chromatography in terms of process performance, namely a reduced desorbent consumption and a higher productivity per unit mass of stationary phase. Moreover, SMBs can be operated using the same method (same stationary phase and mobile phase) adopted for small-scale preparative batch processes. This is constituting the success of the SMB technology as a tool for speeding up the development process of new fine chemical or pharmaceutical products, which represents a major competitive advantage.
Today, modelling, design and optimization of SMB process are regarded to be well established. On the other hand, long term robust/optimized operation of the process is still an open issue. The common practice is to operate the SMB units under suboptimal operating conditions in order to gain the necessary robustness. The operating parameters are tuned manually by experienced operators in order to maintain the product specifications in the long term. Therefore, as SMB applications spread, the SMB process control problem becomes increasingly important.
The chemical process control group has undertaken the development of an SMB control concept. The project has been carried out together with two other departments at ETH-Zurich, namely Institute for Chemical and Bio-Engineering and Institute of Process Engineering.