Claims
- 1. A cyclic process for preparing ethyl tert.-alkyl ethers comprising the steps:
- a) contacting and reacting in a reaction zone, preferably in the liquid phase, a reaction mixture formed by combining a feedstream comprising hydrocarbons having from 4 to 5 carbon atoms and containing isoalkene with a near stoichiometric ratio of ethanol with respect to said isoalkene to produce a reaction product effluent comprising ethyl tert.-alkyl ether, at least 10,000 ppm (wt.) unreacted ethanol and unreacted C.sub.4 -C.sub.5 hydrocarbons;
- b) separating the reaction product effluent from the reaction zone in a distillation column to provide an overhead effluent stream comprising unreacted ethanol and unreacted C.sub.4 -C.sub.5 hydrocarbons and a bottoms effluent stream comprising ethyl tert.-alkyl ether and unreacted ethanol;
- c) passing the bottoms effluent stream to an adsorption zone containing a selective adsorbent to adsorb ethanol and recovering an ether product stream comprising substantially pure ethyl tert.-alkyl ether; and
- d) regenerating the selective adsorbent with a regenerant stream to recover ethanol and to provide a recycle stream comprising ethanol, and returning said recycle stream to said reaction zone.
- 2. The process of claim 1 wherein the selective adsorbent is selected from the group consisting of zeolite 13X, sodium zeolite Y, alumina, silicalite, and mixtures thereof.
- 3. The process of claim 2 wherein the selective adsorbent is configured as multiple layers of adsorbent.
- 4. The process of claim 1 wherein the regenerant comprises at least a portion of the feedstream.
- 5. The process of claim 1 wherein the regenerant comprises at least a portion of the unreacted C.sub.4 -C.sub.5 hydrocarbons.
- 6. The process of claim 1 wherein the isoalkene is selected from the group consisting of isobutylene, isoamylene and mixtures thereof.
- 7. The process of claim 1 wherein the near stoichiometric ratio of ethanol with respect to said isoalkene ranges from about 0.95 to about 1.15.
- 8. The process of claim 1 wherein said distillation column bottom product comprises from about 0.5 wt % unreacted ethanol to about 7 wt %.
- 9. The process of claim 1 wherein said bottoms effluent stream comprises from about 5000 ppm wt to about 2 wt % ethanol.
- 10. The process of claim 1 further comprising passing the overhead effluent stream to a separation zone to recover an unreacted ethanol stream and an unreacted C.sub.4 -C.sub.5 hydrocarbon stream substantially free of ethanol, said unreacted ethanol stream being returned to said reaction zone.
- 11. The process of claim 10 wherein said unreacted C.sub.4 -C.sub.5 hydrocarbon stream substantially free of ethanol comprises less than 500 ppm-wt ethanol.
- 12. The process of claim 1 wherein the ether product comprises less than about 5,000 ppm-wt ethanol.
- 13. The process of claim 1 wherein the ether product comprises less than about 100 ppm-wt ethanol.
- 14. The process of claim 1 wherein at least a portion of said reaction zone is contained in said distillation column.
- 15. The process of claim 1 wherein said contacting and reaction takes place in the liquid phase.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of application Ser. No. 201,590, filed Feb. 25, 1994, U.S. Pat. No. 5,401,887.
US Referenced Citations (7)
Continuation in Parts (1)
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201590 |
Feb 1994 |
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