Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-06-29
2002-11-26
Medley, Margaret (Department: 1714)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S591000, C568S594000, C568S605000, C568S671000, C044S444000, C044S447000
Reexamination Certificate
active
06486362
ABSTRACT:
The invention relates to a process for producing oxygen-containing compounds containing at least one oxygen atom bonded to two distinct carbon atoms which are not bonded together and not comprising a multiple bond. This oxygen-containing compound belongs to the group formed by ethers or to the acetal group.
The production of ether from a hydrocarbon feed containing olefins has been described, for example, in International patent WO-A-94/26685. That document describes the production of a mixture of ether and alcohol by hydrating a feed comprising an olefin containing two to eight atoms in the presence of a catalyst comprising a modified beta zeolite. The examples are limited to the case of forming isopropyl alcohol and diisopropylether from propylene.
U.S. Pat. No. 886,918 describes a process for producing ether(s) of a mixture of ether(s) and alcohol(s) from a feed comprising at least one olefin containing two to seven carbon atoms, introduced into two reaction zones of a conversion unit. The first zone consists of hydrating the olefin to the alcohol. In the second zone, a portion of the lipido-colloid is dehydrated to the ether and a further portion of that alcohol reacts with the olefin introduced into that zone to form the ether. The catalysts used in the hydration and etherification zones contain identical or different acidic zeolites. That process only describes the case where the olefin is propylene.
French patent FR-A-1 576 890 describes a process for preparing acetals by reacting an alcohol containing three to eight carbon atoms and aldehyde generating substances such as trioxane, in the presence of acidic catalysts such as ion exchange resins.
The process of the invention is of particular application to feeds containing linear or branched olefins containing four to seven carbon atoms in their molecule and produced by conventional manufacturing routes such as fluid catalytic cracking (FCC), steam cracking, oligomerisation of olefins containing less than four carbon atoms, or by dimerisation of olefins containing less than four carbon atoms using, for example, the DIMERSOL process from the Institut Francais du Pétrole.
By way of example, gasolines from catalytic cracking units enable different hydrocarbon cuts with a high olefin content to be produced. In future, gasolines used as fuels must contain fewer olefins for environmental reasons. Further, ethers and acetals have high cetane numbers in mixtures. Firstly, the process of the invention can eliminate olefinic FCC gasolines and secondly, it can convert them into ethers or acetals which when added in suitable proportions to gas oils result in a gas oil with a cetane number which is higher than that of the starting gas oil. Further, incorporating these oxygen-containing compounds into the gas oil can produce a gas oil which pollutes less. The invention thus concerns a process for upgrading these olefinic cuts and in particular olefinic cuts from FCC which can also improve gas oil oils obtained in the refinery either by distillation or by transformation of other cuts, for example the gas oil cut from FCC. The invention also concerns a gas oil with an improved cetane number obtained by incorporating at least one oxygen-containing product formed in the process of the present invention. It further concerns the use of these products, ethers and/or acetals and in particular ethers as bases for high cetane number fuels.
In a particular implementation of the invention, the olefins contain five to six carbon atoms and originate from a light gasoline cut leaving a FCC unit. This particular implementation of the invention is better for simultaneous upgrading of both the gasoline cut obtained by cracking by eliminating a large fraction of the olefins it contains to produce a gasoline cut with a lower olefin content, and of the gas oil obtained by cracking by adding at least a portion of the oxygen-containing compounds formed during elimination of the olefins from the gas cut, resulting in the production of a gas oil fuel with a cetane number which is higher than that of the cracked gas oil without additives.
The process of the present invention for producing oxygen-containing compounds containing at least one oxygen atom bonded to two distinct carbon atoms which are not bonded together and not comprising a multiple bond comprises a step a) for hydroformylation of a feed comprising at least one olefin containing four to seven carbon atoms to at least one aldehyde, a step b) for hydrogenating this aldehyde to at least one corresponding alcohol, and a step c) for transforming at least one alcohol obtained from step b) into a mixture of products comprising at least one oxygen-containing compound containing at least one oxygen atom bonded to two distinct carbon atoms which are not bonded together and not comprising a multiple bond. This product mixture comprises at least one oxygen-containing compound containing at least one oxygen atom bonded to two distinct carbon atoms which are not bonded together and not comprising a multiple bond belonging to the ether or to the acetal group.
Step a) of the process of the invention comprises hydroformylation of a feed comprising at least one olefin containing four to seven carbon atoms in its molecule. Hydroformylation transforms the feed containing at least one olefin into at least one aldehyde containing five to eight carbon atoms in its molecule. It is carried out in the presence of a hydroformylation catalyst and a synthesis gas comprising a mixture of carbon monoxide and hydrogen in a H
2
/CO ratio in the range about 0.5:1 to 3:1, normally in the range about 1:1 to 2.3:1 and usually in the range 1.5:1 to 2.3:1.
The hydroformylation process used in the context of the present invention is preferably the KUHLMANN (PCUK) process described in “Reactivity and Structure Concepts in Organic Chemistry”, 1980, volume 1, published by Springer-Verlag, Berlin, Heidelberg, N-Y, pp 165-166.
The catalyst used can be any hydroformylation type catalyst based on cobalt, rhodium or ruthenium. Usually, catalysts based on cobalt or rhodium in the form of carbonyls or carbonyl complexes are used. Preferably, a catalyst based on unmodified carbonyl cobalt is used which has the advantage of being less sensitive than rhodium based catalysts to poisons such as acetylenic compounds, sulphur, halogens, and carboxylic acids. In a particular implementation of the process of the invention, the hydroformylation catalyst used in step a) is dicobalt octacarbonyl Co
2
(CO)
8
.
Hydroformylation uses a mixture of carbon monoxide and hydrogen known as synthesis gas obtained using any method which is known to the skilled person. In particular, said synthesis gas is obtained by partial oxidation of straight run vacuum residues. Synthesis gas normally contains five principal elements, namely hydrogen, carbon monoxide, carbon dioxide, methane and water, and also impurities which originate from the feeds being treated or from the oxygen used, such as argon, nitrogen and hydrogen sulphide.
Manufacturing synthesis gas by partial oxidation usually involves distilling air to obtain a gaseous mixture which is highly enriched in oxygen containing, for example, 95% by volume of oxygen. The petroleum residue is then partially oxidised using this highly oxygen-rich gaseous mixture. The high temperature encourages the formation of soot which can be limited by injecting water vapour.
The gaseous mixture obtained is then enriched in hydrogen by steam converting carbon monoxide which can be encouraged by an excess of steam. After cooling by quenching, the synthesis gas is separated from the acidic gases such as carbon dioxide and hydrogen sulphide using any means which is known to the skilled person such as adsorbing the acidic compounds onto a capture mass or in a basic solution.
Hydroformylation is carried out in a reactor in the liquid phase. The temperature is normally in the range about 100° C. to 200° C., usually in the range about 150° C. to 180° C., and the total pressure is normally in the range about 10 to 50 MPa, usually in the range
Barraque Michel
Forestiere Alain
Gaillard Jean-Ferdinand
Institut Francais du Pe'trole
Medley Margaret
Millen White Zelano & Branigan P.C.
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