Ion exchange treatment of extraction solvent to remove acid...

Details Ion exchange treatment of extraction solvent to remove acid... Ion exchange treatment of extraction solvent to remove acid...

1999-10-15

2001-04-17

Barry, Chester T. (Department: 1724)

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

C210S660000, C210S664000, C210S683000, C210S194000

Reexamination Certificate

active

06217771

ABSTRACT:

FIELD OF INVENTION
The present invention is concerned with the treatment of polar extraction solvents to remove acid contaminants. More particularly the invention relates to the use of ion exchange resins to remove organic acid contaminants from polar extraction solvents.
BACKGROUND OF INVENTION
Solvent extraction is a process used in the petrochemical industry to separate mixtures of different molecular species by contacting the mixture with a solvent that selectively removes certain of the molecular species present in the mixture. An example of a commercial solvent extraction process involves the selective dissolution of aromatic hydrocarbons from paraffinic hydrocarbons using polar solvents such as N-methyl pyrrolidone (NMP), furfural, phenol and the like. Typically, the dissolved aromatic hydrocarbons are recovered from the solvent by rectification, stripping or a combination of these means to recover a solvent containing from about 0.5 to about 5 LV % water. The solvent then is recirculated to contact fresh feed. Over time contaminants from the feed and solvent degradation products accumulate in the solvent phase. These species are acidic and may include carboxylic acids, halogens and other products which are capable of causing severe corrosion in various sections of the plant equipment with which it comes in contact.
Therefore, there is a need for a method of treating recovered extraction solvents to remove contaminants present in them.
SUMMARY OF INVENTION
Accordingly, a method for removing corrosive contaminants from a polar extraction solvent comprises adding water to the solvent to provide a solvent and water mixture and thereafter contacting the mixture with a basic ion exchange resin to remove the contaminants.
The amount of water added to the solvent preferably is an amount sufficient to increase the exchange capacity of the resin for carboxylic acids over that in the absence of water addition.


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patent: 5879540 (1999-03-01), Zinke et al.
patent: 2088850 (1982-06-01), None
Kunin, R. “Ion Exchange Resins”, Robert E. Kruger Publisher, Malabar Fl (1990) p. 337 to 344.
Mod, William A. “Ion-Exchange Agents”, p. 310 in Encyclopedia of Chemical Processing and Design, vol. 27; McKetta, J. J. Ed.© 1988 Marcel Dekker, Inc., NY, NY.
De Dardel, F. and Arden, T.V. Ion Exchangers, p. 404 in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, vol. A14; Elvers, B., Hawkins, S., Ravenscroft, J., and Schulz, G. Edts. ©1989 VCH.

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