Removal of Aromatics from Aliphatics

Purification of aliphatics by the removal of aromatics is important in the petrochemical industry as well as for pollution control. In a typical benzene removal process, a combination of extraction and distillation is used (Meyers, 1986). Improvements by other processes have been considered, such as pervapora-tion (Hao et al., 1997), liquid membranes (Li, 1968 Li, 1971a and 1971b), and adsorption by temperature swing adsorption (TSA) in the liquid phase (Matz and Knaebel, 1990). In the work of Matz and Knaebel, commercially available sorbents were used silica gel, activated alumina, activated carbon, zeolite 13X, 

Takahashi and Yang (2002) studied adsorption of benzene and cyclohexane on various Y-zeolites. AgY showed superior benzene/cyclohexane selectivities to NaY, PdY, and H-USY. Separation factors as high as lO were obtained with AgY at low concentrations of benzene. More details will be given in Chapter 10 (10.8). 

Bailes, P. J. (1983) Petroleum and petrochemicals processing—introduction and aromat-ics-aliphaticsseparation.Inff(zndi ooA 5 o/vcnr riracri n.(T. C., Lo,M. H. I., Baird, and C., Hansen, eds.). Wiley, New York, NY p. 517. 

Blytas, G. C. (1992) Separation of unsaturates by complexing with nonaqueous solutions of cuprous salts. In Separation and Purification Technology. (N. N., Li and I. M., Clao, eds.). Chap. 2. Marcel Dekker, New York, NY. 

(1974) Zeolite Molecular Sieves. WUey, New York, NY. 

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Similar considerations are vahd for organic-organic separation. Spiral-wound modules have thus been used in pilot plants for the removal of methanol and ethanol from dry organic mixtures or for the removal of aromatic from aliphatic components. The stabihty of the material for the feed-side spacer and the glue... 

The pure component adsorption ratios and the separation factors for ben-zene/cyclohexane on these sorbents are shown in Table 8.11. The separation factors were calculated from mixed gas isotherms. Based on these figures, bulk separation with Ag and Cu salts is not promising. However, these sorbents are promising for purification, that is, removal of aromatics from aliphatics, since very high separation factors are obtained at low concentrations of benzene. Due to worldwide environmental mandates, refineries are required to decrease the contents of aromatics in gasoline and diesel fuels. The 7r-complexation sorbents... 

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