Simulated moving bed separation

M. Juza, Development of a high performance liquid cliromatographic simulated moving bed separation from an industrial perspective , J. Chromatogr. 865 35-49 (1999). 

Azevedo D. C. S., Rodrigues A. E. (1999) Design of a Simulated Moving Bed Separator in the Pres-enee of Mass Transfer Resistanees, AIChE J 45 956-966. 

Biressi, G., Quattrini, F., Juza, M., Mazzotti, M., Schurig, V., and Morbidelli, M. (2000) Gas chromatographic simulated moving bed separation of the enantiomers of the inhalation anesthetic enflurane. Chem. Engineer. Sci. 55, 4537-4547. 

Although the most widely used scheme among simulated moving-bed separation processes is the four-zone one described in the first part of this section, there are alternative schemes that are more suited to very particular cases.8,9 Those cases are related to binary to ternary separations. This subject is discussed more extensively in Ref. 10. 

Hotier, G. Process for simulated moving bed separation with a constant recycle rate, US Patent 5.762.806, 1998. 

For other experiments, more complicated boxmdary conditions may be necessary. This is particularly the case for simulated moving bed separations (see Chapter 17). 

FIGURE 14.3-5 Simulated moving-bed separation of ethyl caprale From ethyl lauiale by GLC. 3 Reprinted with permission from the Canadian Journal of Chemical Engineering, 57, 42 (1979). 

Karlsson S. (2001). Optimization of a Sequential-Simulated Moving-Bed Separation Process with Mathematical Programming Methods. Ph.D. Thesis, Abo Akademi University. 

Fig. 8. UOP Parex simulated moving bed for adsorptive separation. AC = adsorbent chamber RV = rotary valve EC = extract column ...

Aromatic and Nonaromatic Hydrocarbon Separation. Aromatics are partially removed from kerosines and jet fuels to improve smoke point and burning characteristics. This removal is commonly accompHshed by hydroprocessing, but can also be achieved by Hquid-Hquid extraction with solvents, such as furfural, or by adsorptive separation. Table 7 shows the results of a simulated moving-bed pilot-plant test using siHca gel adsorbent and feedstock components mainly in the C q—range. The extent of extraction does not vary gready for each of the various species of aromatics present. SiHca gel tends to extract all aromatics from nonaromatics (89). 

Chromatography may also be advantageous when it is required to separate several pure products from a single feed stream. A simulated moving-bed system can yield only two weU-separated fractions from a single feed stream. 

The question of whether adsorption should be done ia the gas or Hquid phase is an interesting one. Often the choice is clear. Eor example, ia the separation of nitrogen from oxygen, Hquid-phase separation is not practical because of low temperature requirements. In C q—olefin separation, a gas-phase operation is not feasible because of reactivity of feed components at high temperatures. Also, ia the case of substituted aromatics separation, such as xylene from other Cg aromatics, the inherent selectivities of iadividual components are so close to one another that a simulated moving-bed operation ia hquid phase is the only practical choice. 

However, ia some cases, the answer is not clear. A variety of factors need to be taken iato consideration before a clear choice emerges. Eor example, UOP s Molex and IsoSiv processes are used to separate normal paraffins from non-normals and aromatics ia feedstocks containing C —C2Q hydrocarbons, and both processes use molecular sieve adsorbents. However, Molex operates ia simulated moving-bed mode ia Hquid phase, and IsoSiv operates ia gas phase, with temperature swiag desorption by a displacement fluid. The foUowiag comparison of UOP s Molex and IsoSiv processes iadicates some of the primary factors that are often used ia decision making ... 

Njlene Separation. -Xylene is separated from mixed xylenes and ethylbenzene by means of the Parex process (Universal Oil Products Company). A proprietary adsorbent and process cycle are employed in a simulated moving-bed system. High purity -xylene is produced. 

Another approach is the simulated moving-bed system, which has large-volume appHcations in normal-paraffin separation andpara- s.yXen.e separation. Since its introduction in 1970, the simulated moving-bed system has largely displaced crystallisation ia xylene separations. The unique feature of the system is that, although the bed is fixed, the feed point shifts to simulate a moving bed (see Adsorption,liquid separation). 

A. Gentilini, C. Migliorini, M. Mazzotti and M. Morbidelli, Optimal operation of simulated moving-bed units for non-linear cliromatograpliic separ ations. II. Bi-Langmuir isotherm , 7. Chromatogr. 805 37-44 (1998). 

S. Nagamatsu, K. Murazumi and S. Makino, Cliiral separation of a pharmaceutical intermediate by a simulated moving bed process , ]. Chromatogr. 832 55-65 (1999). 

E. R. Francotte and R Richeit, Applications of simulated moving-bed cliromatography to the separation of the enantiomers of chiral drugs , ]. Chromatogr. 769 101-107 (1997). 

Cavoy E., Deltent M. E, Lehoucq S., Miggiano D. (1997) Laboratory-Developed Simulated Moving Bed for Chiral Drug Separations. Design of the System and Separation of Tramadol Enantiomers, J. Chrotnatogr. A 769 49-57. 

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