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1. WO1997023438 - PROCESS FOR PREPARING ALKYL ETHERS AND MIXTURES THEREOF

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

Claims:

1. Process for preparing an ether or mixed ether product to be used as a component of motor fuels, said product comprising alkyl-r-butyl ether or amyl-r-butyl ether and heavier tertiary alkyl ethers, said process comprising the steps of
feeding a feedstock containing hydrocarbons, in particular C3_7 hydrocarbons, to a catalytic distillation reactor system,
reacting the C^ isoolefines of the feedstock with an alkanol in the presence
of a catalyst to form tertiary alkyl ethers,
- removing the alkyl ethers from the distillation reactor and substantially all of the unreacted hydrocarbons with the bottoms product of the distillation, and withdrawing an overhead product, which mainly contains an azeotrope of C3 hydrocarbons and the alkanol, the C3 amount of the withdrawn overhead
product corresponding at least essentially to the amount of C3 hydrocarbons in the feedstock, whereby an essential part of the unreacted alkanol is
removed in the form of said azeotrope.

2. The process according to claim 1 , wherein the alkanol comprises methanol or ethanol.

3. The process according to claim 1, wherein the amount of distillate withdrawn from the distillation corresponds at least approximately to the amount of C3 hydrocarbons present in the feed.

4. The process according to claim 1, wherein the distillation of the reaction is carried out in such a way that, at the top of the distillation column, the alkanol is heavier than the hydrocarbons and, at the bottom of the distillation column, the alkanol is lighter than the C4 and heavier hydrocarbons.

5. The process according to claim 1 , wherein the amount of unreacted alkanol removed from the process is controlled by adjusting the concentration of C3 hydrocarbons in the feed.

6. The process according to claim 1, wherein the catalytic etherification reaction is carried out in a reactor or reactor system external to the distillation column by withdrawing a sidestream from the column, combining it with a fresh feed of hydrocarbons and, optionally alkanol, and recirculating it to the external reactor or reactor system.

7. The process according to claim 1 , wherein the catalytic etherification reaction is carried out in a reactor or reactor system external to the distillation column by circulating a sidestream taken from the column through the reactor and returning it to tray below the one from which it was taken, further comprising adjusting the K-value of the alkanol to less than 1 on the trays above the drawoff tray.

8. The process according to claim 6 or 7, wherein the K-value of the alkanol is adjusted to less than 1 on the trays above the drawoff tray.

9. The process according to claim 6 or 7, wherein the reactor effluent is returned to the column at a point where the K-value of the alkanol is greater than 1.

10. The process according to claim 1, wherein the feedstock comprises mainly C3 5 hydrocarbons.

11. The process according to claim 1 , wherein the C3 hydrocarbon concentration of th feed is intentionally kept so small that the mixture formed by the distillate and the bottoms product can be used as such as a component of motor fuel.

12. The process according to claim 1, wherein the alkyl ethers are subjected to furthe processing in order to form a gasoline component.

13. The process according to claim 1, wherein the catalyst comprises an acid cation exchange resin.

14. The process according to any of the previous claims, wherein MTBE, ETBE or a mixture of MTBE and/or ETBE and heavier ethers are prepared.