Patent Application
20110178355
The present invention relates to a method for preparing linear alpha-olefins by oligomerization of ethylene in the presence of an organic solvent and a catalyst.
Methods for the production of linear alpha-olefins by oligomerization of ethylene are widely known in the art. Usually, a catalyst is utilized in that process comprising a zirconium component and an organoaluminum component which acts as an activator.
For example, DE 43 38 414 C1 discloses a process for the production of linear alpha-olefins, wherein one reactor is utilized into which a catalyst solution and ethylene are introduced. That process results in a product distribution of linear alpha-olefins having C4-C28; carbon atoms, wherein the fraction of C20+ usually contains waxy, polymeric substances.
The product stream containing alpha-olefins with C4-C28 carbon atoms may be separated into fractions, e.g. by distillation or extraction. One main fraction obtained is a fraction containing C10+ alpha-olefins, preferably C10-C18. This fraction may be often contaminated by aromatic components, preferably C9+ aromatic components which are formed during oligomerization. Of course, these by-products are not desired, as a less valuable fraction C10+ is provided. In the prior art, the aromatic components have been so far removed by repeated extraction and/or distillation, e.g. five distillation columns have been used so far to remove the aromatic components from the C10+ alpha olefin fraction.
It is therefore an object of the present invention to provide a method for preparing linear alpha-olefins which overcomes the drawbacks of the prior art. Especially, a method shall be provided wherein aromatic by-products, commonly present in the C10+ alpha-olefin fraction, can be easily removed with low costs, in order to improve the value of the C10+ alpha-olefin fraction.
This object is achieved in that a product fraction of C10+ alpha-olefins contaminated with aromatic C9+ compounds is separated from a product main stream and transferred into a conversion reactor, where C10+ alpha-olefins and aromatic C9+ components are reacted in the presence of a Friedel-Crafts alkylation catalyst to produce aromatic C19+ components.
Preferably, the Friedel-Crafts-alkylation catalyst is selected from any material with sufficient acidity to catalyze the alkylation.
More preferably, the Friedel-Crafts-alkylation catalyst is selected from clay, zeolites, Lewis acids and protonic acids.
In one preferred embodiment, the Friedel-Crafts-alkylation catalyst is selected from clay, zeolite, H2SO4, P4O10, H3PO4, AlCl3, FeCl3, SbCl5, SnCl4, BF3, TiCl4 and ZnCl2.
The aromatic C19+ compounds prepared may be preferably separated from unreacted C10+ alpha-olefins in or downwards the conversion reactor, preferably by distillation.
Moreover, it is preferred that the separated C19+ compounds are combined with C20+ residue obtained during the oligomerization.
The aromatic C19+ compounds may be transferred to a further device for thermal use thereof, preferably combustion.
In one preferred embodiment, the conversion in the conversion reactor is conducted at ambient temperature.
Further preferred, additional solvent is added to the fraction of C10+ alpha-olefins prior to introduction into the conversion reactor.
Most preferably, the C10+ alpha-olefin fraction is a C10-C18 fraction.
The invention further provides a reactor system for oligomerization of ethylene to form linear alpha-olefins, preferably utilizing a method according to the invention, comprising an oligomerization reactor and a conversion reactor, wherein a Friedel-Crafts-alkylation catalyst is present in that conversion reactor.
Surprisingly, it was found that the aromatic by-products contained in the C10+ linear alpha-olefin fraction can be easily converted (removed) by reacting the C10+ alpha-olefins with aromatic components, obtained in the oligomerization process, in the presence of a Friedel-Crafts alkylation catalyst in a separate conversion reactor to produce aromatic components having at least C19+. These C19+ aromatic components can be easily separated from the C10+ alpha-olefin fraction and can be further processed, for example, combusted. Thus, the separation of the aromatic by-products is achieved in a very simple method step and safes five distillation columns which have been used so far to separate the aromatic by-products from the alpha-olefins fraction. Therefore, investment and operation costs are decreased, and a value added product (alpha-olefin fraction without by-products) is obtained.
As is obvious for someone skilled in the art, the concept of the present invention may be also adapted to any hydrocarbon streams containing aromatic impurities or by-products. For example, in case of paraffinic streams, olefins have to be added into the paraffinic stream to allow the conversion to heavy aromatic compounds which may be easily separated.
In general, the conversion of linear alpha-olefins (C10+) with aromatic components (C9+) is according to the following scheme:
wherein R′ is any alkyl group having two or more carbon atoms and R is any alkyl group having at least eight carbon atoms, preferably eight to sixteen carbon atoms.
Additional advantages and features of the inventive method and reactor system are further illustrated with reference to the accompanying drawing, wherein
In
The features disclosed in the foregoing description, in the drawing or in the claims may, both separately and in any combination thereof, be material for realizing the invention in diverse forms thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 06005686.8 | Mar 2006 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2007/000812 | 1/31/2007 | WO | 00 | 3/28/2011 |
