Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By addition of entire unsaturated molecules – e.g.,...
Patent
1996-04-08
1998-06-16
Caldarola, Glenn
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By addition of entire unsaturated molecules, e.g.,...
585521, 585800, C07C 208, C07C 704
Patent
active
057673349
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for removing catalyst from an olefinic oligomerization product which includes the steps of oligomerizing one or more olefins in the presence of a BF.sub.3 cocatalyst complex and distilling the oligomerization product while separating vaporized BF.sub.3 cocatalyst complex.
2. The Prior Art
Poly-.alpha.-olefin type base oils are widely used in high quality lubricants. The most preferred starting material for the poly-.alpha.-olefin base oils is 1-decene, which yields a product with excellent viscosity-volatility relationships and high viscosity indices. Such oligomer-derived base oils are especially adapted for use under rigorous conditions and are particularly suitable for general use in an arctic environment. Other olefins are also usually used in oligomerization processes, for example straight or branched C.sub.4 -C.sub.20 olefin, advantageously a C.sub.6 -C.sub.12 olefin-1.
The use of promoted borontrifluoride gives good control of the oligomerization process and furthermore a good conversion of monomer to desired poly-.alpha.-olefin base oils. Borontrifluoride alone is not an active catalyst; it requires a promoter in order to perform as an oligomerization catalyst. The promoter or cocatalyst can be water, alcohol, acid, ether, ketone or mixtures of these. The choice of cocatalyst has a significant impact on the oligomerization. Most commonly alcohols as n-propanol and n-butanol are used. Other cocatalysts may also be used as for example C.sub.1 -C.sub.15 alcohols, advantageously a C.sub.1 -C.sub.10 alcohol, a polyol or C.sub.1 -C.sub.7 carboxylic acids.
BF.sub.3 forms complexes with the cocatalysts. The activity and performance of the BF.sub.3 -complexes as oligomerization catalysts are improved by supplying BF.sub.3 in excess to what is needed for formation of the catalyst complex. Excess BF.sub.3 is supplied by either bubbling BF.sub.3 -gas through the reaction mixture or by carrying out the reaction under BF.sub.3 -pressure.
The BF.sub.3 -cocatalyst complex is either formed in situ in the oligomerization process or it is prepared by contacting BF.sub.3 and cocatalyst prior to introduction to the process.
For those skilled in the art it is obvious that the oligomerization can be carried out in various types of reactor systems where the free BF.sub.3, the catalyst complex and the monomer are brought together. In general the catalyst complexes are not very well soluble in either the monomer or the oligomers formed in the process. Good contact between the three phases is essential in order to achieve an efficient oligomerization process. The oligomerization reaction, as well as the formation of BF.sub.3 -cocatalyst complex, are exothermic reactions, and in order to enable a controlled oligomerization path, the oligomerization system has to be equipped with an adequate cooling system.
Various kinds of reactor systems are known in the prior art for use in oligomerization by liquid phase catalyst complexes e.g., stirred tank reactors operated either in batch or continuous mode, loop reactors, tubular reactors or combinations of the latter. For operation in continuous mode the process can also be carried out in two or more serial-connected reactors. Fixed bed reactors may be used when the catalyst complex is present as a solid.
The oligomerization reactor product consists of unreacted monomer, dimers, trimers and higher oligomers, free and dissolved BF.sub.3 and catalyst complex.
Due to the toxicity and corrosion risks, the catalyst complex and free BF.sub.3 have to be carefully removed from the oligomer product. Especially fluor compounds are harmful for the generally used nickel-based catalyst used for hydrogenating the final products.
Removal of the BF.sub.3 catalyst can be achieved by washing the reactor product with caustic water solution or ammonia water solutions. The alkaline wash is generally followed by aqueous wash in one or more steps to achieve a sufficiently clean oligomer mixture for further proce
REFERENCES:
patent: 2588358 (1952-03-01), Carlson et al.
patent: 4239930 (1980-12-01), Allphin
patent: 4263467 (1981-04-01), Madgavkar
patent: 4956512 (1990-09-01), Nissfolk et al.
patent: 5254784 (1993-10-01), Nurminen et al.
Alastalo Kauno
Lehtinen Vesa-Matti
Linnaila Raimo
Nissfolk Fredrik
Smeets Ivo
Caldarola Glenn
Dang Thuan D.
Neste Alfa Oy
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