Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By addition of entire unsaturated molecules – e.g.,...
Patent
1994-02-10
1996-04-23
Cross, E. Rollins
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By addition of entire unsaturated molecules, e.g.,...
585510, 585520, 502232, 502233, 502237, 502238, 502240, 502245, 502258, 502259, C07C 202, C07C 204, B01J 2108, B01J 2112
Patent
active
055105556
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a catalytically active silica-alumina-nickel oxide gel, the process for its preparation and its use in processes of dimerization of isobutene into alpha- and beta-diisobutene and oligomerization of propylene into its relative dimers and trimers.
The conventional processes as used in the dimerization of isobutene are generally based on the use of an acidic catalyst, such as sulphuric acid, polyphosphoric acid (in liquid form or supported by an inorganic solid); heteropolyacids i.e. phosphomolybdic and silicotungstic acid; ion exchange resins of the polystyrenesulphonic or fluorosulphonic type; boron trifluoride complexed with alcohols; organic acids, esters, ethers, ketones; aluminium trichloride associated to ethyl ether; hydrochloric acid or nitromethane; simple or complex salts, especially nickel salts activated with an aluminium alkyl, or an aluminium alkyl halide; and metal oxides, as bismuth oxide optionally associated with a phosphor oxide.
Catalysts capable of oligomerizing olefins such as polypropylene and butenes are, again, aluminosilicates and zeolites optionally modified with salts or oxides of metals such as nickel, chromium and cobalt, as for instance described in U.S. Pat. No. 3,518,323 and U.S. Pat. No. 3,525,456, in EP-A-132 172, EP-A-224 220, EP-A-133 052.
Finally, in U.S. Pat. No. 3,960,978, U.S. Pat. No. 4,150,062, as well as in EP-A-311.675 processes are described for the production of gasoline by means of olefin oligomerization with ZMS-5 type zeolites.
The gasolines so obtained also contain a fraction of aromatic hydrocarbons, mainly benzene, that which is undesirable due to its toxicity towards human beings and the environment.
Many of the conventional oligomerization catalysts have drawbacks due to the corrosive action of the acids that are used, to the requirement of disposing of the exhausted catalysts, their limited life and/or the cost of their preparation. A problem which is common to these conventional catalysts lies in their poor selectivity to the desired reaction products. For instance, when used in the dimerization of isobutene, they cause the formation of relevant amounts of higher oligomers and isomers other than the most appreciable ones, that is, alpha- and beta-diisobutene.
Finally whenever an isobutene stream admixed with other C4 olefins undergoes dimerization, codimers are usually and concurrently produced.
This is believed to be due to the comparatively high temperatures are which the conventional catalysts unfold their activity, or the exceedingly high acidity of the catalysts themselves, which encourage molecular rearrangements or other undesirable side-reactions.
EP-A-340.868 discloses an amorphous and microporous silica-alumina gel which is active in processes of isomeriztion, alkylation, dewaxing and dimerization of linear olefins.
According to the present invention it has now been ascertained that the introduction of a limited amount of nickel oxide in a gel of the type suggested in the aforementioned EP-A 340 868 makes it possible to obtain a catalyst having an even and controlled porosity, essentially free from any isomerizing capability and capable of dimerizing isobutene into alpa- and beta-diisobutene with a surprisingly high selectivity. It is therefore possible to obtain high quality products, useful as chemical intermediate or in the preparation of high-octane gasoline. It has furthermore been ascertained that such a catalyst is active in the oligomerization of propylene into dimers and trimers, which are useful, as such or after etherification, as high-octane gasolines.
According to the foregoing, a first aspect the present invention relates a silica-alumina-nickel oxide gel, amorphous to X-rays, having an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio of from 30/1 to 500/1, and NiO/SiO.sub.2 molar ratio of from 0,001/1 to 0.05/1, a surface area from 500 m.sup.2 /g to 1.000 m.sup.2 /g, a mean pore diameter of about 1 nm (10 .ANG.) (Angstrom), and a porosity from 0,3 ml/g to 0,6 ml/g, devoid of pores having a diameter over
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Bellussi Giuseppe
Brunelli Maurizio
Castelvetro Walter
Peratello Stefano
Cross E. Rollins
Eniricerche S.p.A.
Irzinski E. D.
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