Enantioseparation through Supercritical Fluid Simulated Moving Bed (SF-SMB) Chromatography

Abstract

In this work, the first enantioseparation in a SF-SMB unit, i.e., a simulated moving bed (SMB) operated under supercritical conditions, is reported. Complete separation of the two enantiomers of tetralol was achieved both in the pressure-gradient mode (where a pressure gradient is imposed along the four sections of the unit) and in the isocratic mode (where the pressure is kept constant). However, an almost 3-fold increase in productivity could be achieved in the pressure-gradient rather than the isocratic mode. The obtained results are explained and rationalized using recently developed design criteria for SMBs, the so-called "triangle theory", which have been properly extended to allow for different pressure values in the different sections of the unit.

Effect of pressure drop on solute retention and column efficiency in supercritical fluid chromatography Part 2: Modified carbon dioxide as mobile phase

“…This behavior stems from the fact that the solvent shows increased solubilities at high pressures and competes for adsorption sites with the solute [12 -15]. This is a unique property that allows the implementation of gradients in preparative applications, which can potentially lead to increased productivities [8,16,17].…”

Continuous chromatographic processes with a small number of columns: Comparison of simulated moving bed with Varicol, PowerFeed, and ModiCon

“…In fact, there is a clear trend in applications to operate SMB with 5 or 6 columns, instead of 8, which was previously regarded as the minimum number of columns for SMB units. The second approach aims at improving the unit's separation efficiency either by optimizing the adsorptivity of the solutes in the different sections of the unit, such as in supercritical fluid SMB [Nicoud and Perrut, 1992;Mazzotti et al, 1997b;Di Giovanni et al, 2001;Denet et al, 2001], temperature gradient SMB [Migliorini et al, 2001] and solvent gradient SMB [Jensen et al, 2000;Antos and Seidel-Morgenstern, 2001;Abel et al, 2002;Houwing et al, 2003], or more recently by operating SMB under more complex dynamic conditions, as it is the case in the Varicol Zhang et al, 2002Zhang et al, , 2003aToumi et al, 2003;Pais and Rodrigues, 2003], PowerFeed [Kearney and Hieb, 1992;Kloppenburg and Gilles, 1999;Zang and Wankat, 2002a, b;Zhang et al, 2003bZhang et al, , 2004 and ModiCon [Schramn et al, 2002[Schramn et al, , 2003 processes. These new operation modes do not keep constant conditions during one switching period t * , as in a standard SMB, but allow for variation of the column configuration, the fluid flowrates, or the feed concentration, respectively.…”

Simulated Moving Bed Chromatography: From Concept to Proof‐of‐Concept

“…Most of the industrial applications of SMB technology operate in the liquid phase; nevertheless, SMBs can also be operated under supercritical conditions where a supercritical fluid, typically CO 2 , is used as eluent offering a number of advantages, namely, reduction of eluent consumption, favorable physicochemical properties, lower pressure drop, and higher column efficiency [88,[102][103][104][105][106]. Also, recent developments related with the operation of SMB units in the gas phase were found to be remarkable, either for fine chemical resolution [107][108][109][110] or for bulk chemicals [111][112][113][114][115][116][117].…”