Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By addition of entire unsaturated molecules – e.g.,...
Reexamination Certificate
1998-07-06
2002-09-03
Dang, Thuan D. (Department: 1764)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By addition of entire unsaturated molecules, e.g.,...
C585S523000, C585S527000, C585S531000
Reexamination Certificate
active
06444866
ABSTRACT:
BACKGROUND OF THE INVENTION
The field of olefin transformation has been widely studied and is the subject of a number of patents. Particularly important processes are those which enable long chain oligomers to be produced. Depending on the number of carbon atoms in the chain, such oligomers have applications in the chemicals and petrochemicals industries, or are components of gasoline. The reactions which are of interest in the present invention are dimerization, co-dimerization or oligomerization of olefins.
The prior art contains numerous patents. Of those, we shall describe patents in which the catalysis reaction is carried out in a homogeneous liquid phase with a soluble catalyst, or heterogeneous catalysis is carried out with a solid catalyst. Such processes have disadvantages, however: the catalysts used—often nickel based—are expensive. Solid catalysts deactivate by the action of pollutants, and they must be regularly regenerated or replaced. For soluble catalysts, the outlet effluent contains catalyst which must be separated out, involving unavoidable supplemental expense. In addition to the degree of conversion, which varies depending on the olefin to be treated—for n-butenes, the maximum degree of conversion of economic interest is 80% —, the reaction is generally not sufficiently selective; finally, a mixture of products is obtained—which is not always desirable—and which must be separated out.
SUMMARY OF THE INVENTION
The present invention uses a sequence of processes to carry out dimerization, co-dimerization or oligomerizing olefins in two steps. In the remainder of the text, the term “oligomerization” covers these three types of reactions.
The first step is catalytic oligomerization which may be of the homogeneous liquid phase type or of the heterogeneous type. The term “heterogeneous catalysis reaction” used in this text defines a reaction where two phases co-exist, the catalyst being solid. The second step is catalysis in a two-phase medium where the catalyst is dissolved in a polar phase which is not miscible with the organic phase containing at least one olefin. Among the advantages of this invention are a large increase in the reaction yield, and an increase in selectivity, so the reaction can be better oriented towards the species which are to be obtained. The second step of the reaction is particularly selective for dimers, which is the species which is most frequently desired. The invention also enables the pollutants present in the apparatus to be closely controlled, as any pollutants present in the initial feed will have been partially eliminated in the first step. If necessary, they can also be completely eliminated by an intermediate treatment. In a particular implementation of the invention, catalyst wastage can be reduced by better use of the catalyst in the two-phase medium. The first step of the process is thus homogeneous catalysis in which at least part of the catalyst is recovered with the effluent. The catalyst is then used in the liquid-liquid two-phase catalysis step.
Processes for homogeneous liquid phase catalysis or heterogeneous catalysis can convert feeds containing olefins, particular propylene or n-butenes. These processes can treat feeds containing 50% to 100% by weight of olefins, usually 70% to 90% by weight. However, these processes are not limited to the treatment of these feeds alone, in particular it has been verified that they also work for feeds containing olefins with a carbon chain containing two, five or six carbon atoms. For feeds containing less than 50% by weight of olefins, in particular for propylene or n-butenes, the consumption of catalyst or the size of the reactors renders the process less economical, the costs being higher as the feed becomes more diluted and the olefin less reactive. Similarly, the cost is large for olefins with a carbon chain containing more than four carbon atoms, which is why such homogeneous liquid phase catalysis or heterogeneous catalysis processes are particularly suitable for olefins containing three or four carbon atoms. Further, the selectivity for dimers—which is the product which is most in demand—strictly depends on conversion: for butenes, it does not exceed 85% for a feed converted in an amount of 80% by weight. The liquid-liquid two-phase process can convert dilute feeds, i.e., containing less than 50% by weight of olefins, and can also produce a higher selectivity for dimers, this selectivity possibly reaching 95%; further, this liquid-liquid two-phase process renders the conversion to dimers less dependent on the starting feed.
Prior art heterogeneous catalysis processes which can be used in the first step of the invention use catalysts containing a metal, preferably nickel, on a to support which can, for example, be alumina, silica, silica-alumina, a zeolite or a silico-aluminate. The reaction temperature is about 10° C. to 250° C., the pressure being such that the feed remains liquid. French patent French application No. 2,608,594 describes a process for dimerizing olefins using heterogeneous catalysts comprising nickel compounds deposited on alumina. The heterogeneous catalysis catalysts in the first step of the invention can also be a mineral compound alone, the mineral compound being, for example, a silico-aluminate, a zeolite or a silica-alumina. IFP Enterprises markets a silica-alumina compound under trade reference IP501, for example.
Prior art descriptions concerning homogeneous liquid phase processes propose the use of different types of catalysts depending on the olefins to be treated and also depending on the product which is particularly desired, those catalysts all containing at least one compound of a metal, preferably nickel, and an alkoylaluminium halide. The reaction temperature is about −40° C. to +100° C., the pressure is such that the reactants are at least partially, normally mainly in the liquid phase and the stirring conditions are those necessary to convert at least a portion of the feed.
For oligomerization, in particular dimerization and trimerization, of olefins, United States patent U.S. Pat. No. 4,316,851 recommends the use of mixed nickel compounds with general formula (R
1
COO)(R
2
COO)Ni where R
1
is an alkyl, cycloalkyl, alkenyl, aryl, aralkyl or alkaryl residue, for example, containing at least 5 carbon atoms, preferably an alkyl residue containing 5 to 20 carbon atoms, this residue possibly being substituted by hydroxyl groups, for example, and R
2
is a halogenoalkyl residue containing 1 to 3 carbon atoms, with formula C
m
H
p
X
q
where m=1, 2 or 3, p equals zero or a whole number and q is a whole number, with the condition that p+q=2m+1. R
2
is preferably a halogenomethyl residue CX
n
H
3−n
where X is fluorine, chlorine, bromine or iodine, and n is a whole number from 1 to 3.
The preparation of catalysts for dimerization or co-dimerizing C
2
, C
3
or C
4
olefins is also well known, the catalysts resulting, for example, from the interaction of halides of &pgr;-allyl nickel phosphine with Lewis acids (French application No. 1,410,430), from the interaction of halides of nickel phosphine with Lewis acids (U.S. Pat. No. 3,485,881) or from the interaction of certain nickel carboxylates with alkylaluminium halides (U.S. Pat. No. 3,321,546). Similarly, U.S. Pat. No. 4,404,415 describes dimerizing propylene to higher oligomers: nonenes or mixtures of nonenes and dodecenes, the type of catalyst used being a complex in which a metal, preferably nickel, is bonded to at least one unsaturated hydrocarbon residue, which may or may not be substituted, for example a bis-&pgr;-allyl nickel, a &pgr;-allyl nickel halide or bis-cyclooctadiene nickel associated with a halogenated aluminum compound. A further catalyst type is constituted by complexes formed by mixing at least one nickel compound with at least one alkylaluminum compound and possibly a ligand, for example a phosphine. A preferred class of catalysts comprises catalysts obtained by mixing at least one nickel carboxylate (the carboxylate residue contai
Commereuc Dominique
Forestiere Alain
Hughes Francois
Olivier-Bourbigou Helene
Dang Thuan D.
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
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