Method of Production Adsorbent-Desorbent

A simulated moving bed system has been proposed for the production of p-cresol from mixtures of cresol isomers even derived from coal tar [52]. Neuzil et al. give details of the development of the adsorbent and desorbent system reviewing balancing mass transfer issues with selechvity [53]. The desorbent for the cresol system is 1-pentanol. For these Hquid adsorptive systems where highly polar molecules are adsorbed and desorbed with polar desorbents, the tolerance of the system for trace polar contaminants is higher because the feed and desorbent can more easily exchange with them on the surface of the zeolites. 

Any contaminants that come with the feed tend to not permanently stay on the adsorbent, as in completely non-polar systems seen in the other aromatic applications. 

Expansion of Sorbex technology to the production of m-xylene shows how the process concept can be used for multiple applications in separations that cannot be performed by other means. One can expect that, as demand for new, difficult to separate aromatics increases, the simulated moving bed liquid adsorption processes can provide a means for production. 

1 Methivier, A. (1998) Influence of oxygenated contaminants on the separation of C8 aromatics by adsorption of faujasite zeolites. Ind. Eng. Chem. Res., 37, 604-608. 

2 Wittcoff, H. and Reuben, B. (1996) Industrial Organic Chemicals, John Wiley Sons, Inc., New York, pp. 348-350. 

---