Abstract: Catalytic process for metathesis of olefins in the presence of a catalyst and a stabilizing agent that is injected into the reaction medium. Application in particular to rebalancing between one another the light olefins that are obtained from steam cracking or catalytic cracking (FCC), such as ethylene, propylene, butenes or pentenes.

Abstract: Propene and, if desired, 1-butene are prepared by first reacting 1-butene and 2-butene to give propene and 2-pentene in the presence of a metathesis catalyst containing at least one compound of a metal of transition group VIb, VIIb or VIII of the Periodic Table of the Elements. The propene and 2-pentene formed are subsequently separated, and the 2-pentene is then reacted to give propene and 1-butene in the presence of a metathesis catalyst containing at least one compound of a metal of transition group VIb, VIIb or VIII. The propene and 1-butene formed are subsequently separated, and at least some of the 1-butene is discharged or at least partly isomerized to give 2-butene in the presence of an isomerization catalyst. Undischarged 1-butene and the 2-butene formed are subsequently returned to the initial reaction step, together with that part of the C4 fraction which was not reacted in the initial reaction step.

Abstract: A composition and method for the catalytic conversion of a racemic mixture of dienes to a cyclic olefin by a ring-closing metathesis (RCM) reaction are disclosed. The composition, a transition metal complex with an M═C reaction site, contains a bidentate dialkoxide of at least 80% optical purity. Because the M═C reaction site is of a sufficient shape specificity, conferred in part by the dialkoxide of sufficient rigidity and a M═N—R1 site, reacting the composition with a mixture of two enantiomeric dienes results in an olefin metathesis product that has at least a 50% enantiomeric excess of one enantiomer in the mixture. A method is also provided for reacting a composition with a racemic diene mixture to generate a metathesis product that has an enantiomeric excess of at least 50%. Methods are also provided for catalytic enantioselective desymmetrization.

Abstract: The process for preparing propene and hexene from a raffinate II feed stream comprising olefinic C4-hydrocarbons comprises

Abstract: This invention pertains to a continuous catalytic process, for example, for the metathesis of olefins that uses a catalyst circulating in a moving bed in at least one reaction zone operating in the liquid phase and in a regenerator, with a lift to transfer the deactivated catalyst emerging from the reaction zone to the regenerator, whereby said process is characterized by the fact that the transfer is accomplished by a gas that does not react with the catalyst and with the stripping off of at least a portion of the organic matter that is adsorbed on the deactivated catalyst.

Abstract: The present invention relates to a process for continuous metathesis or disproportionation of olefins, comprising at least 2 phases, a reaction phase a) carried out in a zone comprising at least one reactor containing at least one fixed bed of catalyst and a regeneration phase b) carried out in a zone comprising at least one reactor containing at least one fixed bed of catalyst, characterized in that at least one reactor passes from one phase to the other in alternation. In FIG. 1, the feed containing olefins traverses reactor R1 in riser mode. The feed to be treated containing olefins is introduced into reactor R1 via line 1a. In this reactor, the olefins contained in the feed undergo metathesis or disproportionation, then the effluent leaves the circuit via line 11. Simultaneously, reactor R2 is placed in catalyst regeneration phase, the different regeneration gases are introduced into reactor R2 via line 2b and leave this reactor via line 2c.

Abstract: The present invention relates to a process for preparing propene by metathesis of olefins.

Abstract: The present invention provides a process for converting olefinic C5 cuts by metathesis using an improved catalyst containing rhenium, cesium, and delta alumina. The preferred catalysts contains at least one rhenium compound deposited on a support principally composed of alumina, treated at a temperature of more than 750° C., and modified by at least one cesium compound. Thus the duration of the cycle between two regeneration operations is substantially increased.

Abstract: The preparation of olefins from steam cracker or refinery C.sub.4 streams is carried out by selective hydrogenation of butadienes and acetylenic impurities in the steam cracker or refinery C.sub.4 stream, with simultaneous or subsequent, at least partial isomerization of 1-butene to 2-butene, followed by removal of i-butene from the C.sub.4 stream by reaction with an alcohol to form an ether, followed by removal of oxygen-containing impurities from the C.sub.4 stream using adsorber materials, followed by two-stage metathesis of the butenes in the C.sub.4 stream by conversion of 1-butene and 2-butene present in the C.sub.4 stream into propene and 2-pentene and subsequent reaction of the 2-pentene with ethene in the presence of a metathesis catalyst to form propene and 1-butene. Optionally, butadiene may be removed from the C.sub.4 stream by extractive distillation in a preliminary step.

Abstract: A catalyst containing Re.sub.2 O.sub.7 on an inorganic support, wherein the Re.sub.2 O.sub.7 component is on the support in the form of Re.sub.2 O.sub.7 particles having a diameter of <1 nm, the rhenium surface area, determined by N.sub.2 O pulse chemisorption, is at least 0.4 m.sup.2 /g, and the Re.sub.2 O.sub.7 component is distributed over the support in the form of an outer shell having a maximum thickness of 1.5 mm.

Abstract: The present invention relates to a process for the production of light olefins comprising olefins having from 2 to 4 carbon atoms per molecule from an oxygenate feedstock. The process comprises passing the oxygenate feedstock to an oxygenate conversion zone containing a metal alumninophosphate catalyst to produce a light olefin stream. The light olefin stream is fractionated and a portion of the products are metathesized to enhance the yield of the ethylene, propylene, and/or butylene products. Propylene can be metathesized to produce more ethylene, or a combination of ethylene and butene can be metathesized to produce more propylene. This combination of light olefin production and metathesis, or disproportionation provides flexibility to overcome the equilibrium limitations of the metal aluminophosphate catalyst in the oxygenate conversion zone. In addition, the invention provides the advantage of extended catalyst life and greater catalyst stability in the oxygenate conversion zone.

Abstract: A process for treating unsaturated hydrocarbons comprises subjecting an unsaturated hydrocarbon component to metathesis in the presence of a catalyst system comprising silica, alumina and an alkyl tin compound, thereby to form one or more different hydrocarbons.

Abstract: The invention relates to a heterogeneous metathesis catalyst containing a support, a metal compound chosen from the group consisting of tungsten, rhenium and molybdenum, and a promoter, the promoter consisting of a niobium compound. The catalyst according to the invention has a high activity at low temperatures. The invention also relates to a process for the metathesis of olefins.

Abstract: For the conversion of an olefinic C.sub.4 or C.sub.5 cut to an alkyl-tertiobutylether or alkyl-tertioamylether and to propylene, by metathesis, the process comprises four successive steps: (1) selective hydrogenation of the diolefins with simultaneous isomerisation of the alpha olefins to internal olefins; (2) etherification of the isoolefins; (3) elimination of oxygen-containing impurities; (4) metathesis of internal olefins with ethylene. The process has application, e.g., to C.sub.4 and C.sub.5 steam cracking cuts.

Abstract: A supported catalyst with rhenium and also containing aluminium introduced by a compound of the formula (OR).sub.qAlR'.sub.r with R being a hydrocarbyl residue with from 1 to 40 carbon atoms, R' being an alkyl residue with from 1 to 20 carbon atoms, and with q and r equal to 1 or 2 with q+r=3. A process for the preparation of a catalyst comprising impregnating a compound of rhenium on a porous support formed by refractory oxides and/or alumino-silicates of an acid, neutral or basic nature, roasting at a temperature of form 200 to 950.degree. C. and impregnating with said aluminium compound. The catalyst is used for the metathesis of olefins.

Abstract: A composition and an olefin conversion process are disclosed. The composition comprises a zeolite having incorporated therein a coke-suppressing amount of a coke suppressor selected from the group consisting of silicon oxides, phosphorus oxides, boron oxides, magnesium oxides, tin oxides, titanium oxides, zirconium oxides, molybdenum oxides, germanium oxides, indium oxides, lanthanum oxides, cesium oxides, and combinations of any two or more thereof. The olefin conversion process comprises contacting a first olefin with a catalyst composition under a condition effective to convert said first olefin to a second olefin wherein the catalyst composition is the same as the composition disclosed above. Also disclosed is a process for producing the composition.

Abstract: The present invention concerns a process for the conversion of an olefinic C.sub.4 cut to polyisobutene and to propylene by metathesis. The process comprises three successive steps: (1) selective hydrogenation of diolefins with simultaneous isomerisation of 1-butene to 2-butenes, (2) polymerisation of the isobutene, including optional prior extraction of the isobutene, (3) metathesis of 2-butene with ethylene. Part or all of the C.sub.4 cut may originate from the metathesis of an olefinic C.sub.5 cut with ethylene after hydroisomerisation of the C.sub.5 cut. Application to C.sub.4 and C.sub.5 steam cracking cuts.

Abstract: The present invention provides a process for olefin metathesis. The process comprises (a) providing a reaction mixture comprising an olefin, a metathesis initiator, and a reaction medium comprising carbon dioxide, and (b) reacting the reaction mixture to provide a metathesis modified olefin. The olefin metathesis reaction may be an olefin metathesis exchange reaction, an olefin metathesis degradation reaction, or a metathesis polymerization reaction. The carbon dioxide medium may be liquid, supercritical, and gaseous carbon dioxide.

Abstract: The present invention concerns new catalytic compositions containing at least one compound of rhenium and aluminium corresponding to the general formula: O.sub.3 Re--O--?Al(OR)(L).sub.x --O!.sub.n --ReO.sub.3 in which R is a hydrocarbyl residue, for example alkyl, cycloalkyl, alkenyl, aryl and aryl or cycloalkyl which are substituted, containing from 1 to 40 carbon atoms, which residue can be substituted by alkoxy groups or by halogens, L is the synthesis solvent, x is equal to 0 or 1 and n is an integer of from 1 to 10. The invention also concerns the preparation of such compositions and the use thereof for the metathesis of olefins in a homogeneous phase.

Abstract: A process for the preparation of organic compounds or polymers containing one or more sulphur atoms and including one or more double bonds in a hydrocarbon chain is described. An acyclic sulphur-containing olefin or an unsaturated sulphur-containing cyclic hydrocarbon undergoes a self metathesis reaction or a cross metathesis reaction with a non-sulphur-containing acyclic olefin or a non-sulphur-containing unsaturated cyclic hydrocarbon to produce novel olefins, novel dienes, and/or olefinic polymers containing one or more sulphur atoms.

Abstract: The invention relates to the use of cyclic organometallic compounds as components in coordination catalyst systems, to corresponding coordination catalyst systems and also to processes for the preparation of polymers by coordination polymerization and of unsaturated hydrocarbons by catalyzed metathesis of alkenes and alkynes using such coordination catalyst systems.

Abstract: The invention concerns a catalytic olefin disproportion (also known as metathesis) process wherein the catalyst produced by dissolving a tungsten and/or molybdenum compound, more particularly a tungsten and/or molybdenum halide substituted with one or more phenoxo groups containing at least two hydrocarbon substituents in the ortho, ortho' positions, in a medium produced by mixing at least one quaternary ammonium halide and/or at least one quaternary phosphonium halide, at least one aluminium halide, and an organometallic aluminium compound.

Abstract: A method is provided for selectively producing a trans-geometrical isomer of non-conjugated diolefins. The method comprises treating a starting non-conjugated diolefin isomer or mixture of isomers, a first mono-olefin and a second mono-olefin with a metathesis catalyst under selected reaction conditions to produce a product with greater than 80% trans-geometrical isomer content. In a preferred embodiment, 1,4-hexadiene, ethene, and propene contact a Re.sub.2 O.sub.7 catalyst and are converted to a reaction product mixture with above 80% trans-1,4-hexadiene.

Abstract: The present invention concerns new compounds of rhenium and aluminum corresponding to the general formula: O.sub.3 Re--O--[Al(OR)(L).sub.x --O].sub.n --ReO.sub.3 in which R is a hydrocarbyl residue, for example alkyl, cycloalkyl, alkenyl, aryl and aryl or cycloalkyl which are substituted, containing from 1 to 40 carbon atoms, which residue can be substituted by alkoxy groups or by halogens, L is the synthesis solvent, x is equal to 0 or 1 and n is an integer of from 1 to 10. The invention also concerns derived compounds of the formula O.sub.3 Re(L')--O--[Al(OR)(L).sub.x --O].sub.n --ReO.sub.3 (L') in which L' is a stabilising ligand. The invention also concerns the preparation of such compounds and the use thereof in the preparation of catalysts.

Abstract: A process for the preparation of optically active cycloolefins based upon reaction of optically active dienes in the presence of catalyst compositions comprising molybdenum and tungsten complexes.

Abstract: 1,1,2,3,4,4,6-Heptamethyl-1,2,3,4-tetrahydronaphthalene, a novel naphthalenic compound, is useful as an intermediate for the preparation of 5,6,7,8-tetrahydro-3,5,5,6,7,8,8-heptamethyl-2-naphthalenecarbaldehyde. It is prepared by a process consisting in the addition of an olefin of formula ##STR1## wherein R.sup.1 and R.sup.2 represent different substituents and each defines a hydrogen atom or a methyl radical, with p-cymene. 4,4-Dimethyl-2-pentene [compound (III): R.sup.1 =CH.sub.3 ; R.sup.2 =H] is obtained by the co-metathesis reaction of an olefin of formula ##STR2## wherein R.sup.1 and R.sup.2 represent identical substituents designating each a hydrogen atom or a methyl radical, with an olefin of formula ##STR3## wherein R.sup.3 and R.sup.4, identical or different, designate each a hydrogen atom or a methyl radical in the presence of an appropriate catalyst consisting of Re.sub.2 O.sub.7 on an inert solid carrier, or of WCl.sub.6 /(C.sub.2 H.sub.5).sub.2 O/Bu.sub.4 Sn.

Abstract: A disproportionation catalyst for olefins and a process for disproportionation of olefins using said catalyst are disclosed. The catalyst is a mixture of one part by weight of a first catalyst component comprising silica gel carrying thereon a tungsten oxide or its precursor and a Group I metal oxide or a compound convertible to Group I metal oxide; and 8-75 parts by weight of a second catalyst component which is alumina having a specific surface area of 20-120 m.sup.2 /g, and preferably carrying thereon a Group I or Group III metal oxide or a compound convertible to such an oxide. It exhibits a remarkably extended life of disporportionation activity and is thus applicable to the industrial use. The catalyst, therefore, can produce industrially useful compounds at a low cost by the application of the olefin disproportionation.

Abstract: Propylene is produced from the disproportionation of impure butene-2 containing oxygenates and butene-1 by treatment with alumina and isomerization of the butene-1 prior to disproportionation with ethylene.

Abstract: This present invention relates to a disproportionation catalyst and to a process for preparing a disproportionation catalyst comprising forming a calcined composite comprising at least one of molybdenum and rhenium supported on an inorganic oxide support and contacting the calcined composite with an organoborane compound. The invention further relates to a process for the disproportionation of olefinic hydrocarbons comprising contacting at least one olefinic hydrocarbon with a catalyst comprising at least one of molybdenum and rhenium supported on an inorganic oxide support promoted with an organoborane compound. More specifically, the invention relates to the uses of an organoborane compound promoted molybdenum and rhenium supported on an inorganic oxide support for the production of linear alpha olefins from a mixture of internal olefins and ethylene.

Abstract: This invention relates to a process for treating olefinic hydrocarbon mixtures with a catalyst system comprising an admixture of a disproportionation catalyst comprising an element selected from the group consisting of molybdenum, tungsten, rhenium and mixtures thereof, and optionally cobalt, and an isomerization catalyst prepared by impregnating a porous alumina support with a metal compound decomposable to an oxide upon calcination wherein said metal is selected from the group consisting of potassium, rubidium, cesium and mixtures thereof and subsequently calcining the resulting material at a temperature of from about 450.degree. C. to about 750.degree. C., thus producing increased yields of detergent range, i.e., C.sub.10 -C.sub.16, olefins.

Abstract: This present invention relates to a disproportionation catalyst and a process for preparing a disproportionation catalyst comprising forming a calcined composite comprising at least one of molybdenum and rhenium supported on an inorganic oxide support and contacting the calcined composite with an organosilane compound selected from the group consisting of silanes containing at least one silicon-hydrogen bond per molecule, silanes containing at least one silicon-silicon bond per molecule and mixtures thereof, and to a process for the disproportionation of olefinic hydrocarbons comprising contacting at least one olefinic hydrocarbon with a catalyst comprising at least one of molybdenum and rhenium supported on an inorganic oxide support promoted with an organosilane compound selected from the group consisting of silanes containing at least one silicon-hydrogen bond per molecule, silanes containing at least one silicon-silicon bond per molecule and mixtures thereof.

Abstract: There is disclosed an improved process for the production of linear alkylbenzene wherein monoolefins are reacted with benzene in a hydrogen fluoride catalyzed reaction followed by recovery of the alkylbenzene. An alumina treatment step is included which removes organic fluoride impurities in order to prevent release of hydrofluoric acid in downstream equipment. It has been discovered that the SO.sub.3 sulfonation color of the alkylbenzene is surprisingly improved by the use of a high selectivity basic alumina for this treatment.

Abstract: A metathesis process of the conversion of olefines, in which at least one olefine is brought into contact with a solid catalyst system comprising on a solid silica carrier 0.1-40% by weight of a tungsten compound under reaction conditions such that the catalyst system converts the olefine into olefines having a different molecular weight. In the process a magnesium oxide or titanium oxide containing co-gel prepared by means of a co-gelling system is used as the silica carrier.

Abstract: A disproportionation catalyst comprising an ammonium or an alkali metal tungsten oxide and a process for forming disproportionation product using the disproportionation catalyst are disclosed. The disproportionation process is used to facilitate the separation of at least one 1-olefin from a mixture of olefins that have close boiling points by contacting the mixture of olefins with another 1-olefin under disproportionation conditions to produce disproportionation products which have significantly different boiling points among themselves and can be easily separated by conventional means.

Abstract: This invention is a two step process for converting linear paraffins to linear alpha olefins. In the first step the paraffins are cracked to a mixture of alpha and internal olefins by use of a cracking catalyst of a zeolite in combination with an alkali(ne earth) metal compound wherein the sum of the amount of the alkali(ne earth) metal in the compound plus any metal cation exchanged into the zeolite is in excess of that required to provide a fully metal cation-exchanged zeolite. The resulting olefin-containing cracked product is then converted to a substantially alpha olefin-containing product by contact with ethylene and a disproportionation catalyst at disproportionation conditions. The resulting products contains only small amounts of aromatics.

Abstract: The invention pertains to rhenium (VII) compounds which are catalysts for metathesis of ordinary olefins (hydrocarbons) and functionalized olefins in a homogeneous phase and to methods of synthesizing these compounds. The rhenium compounds comprise a rhenium (VII) atom centrally linked to an alkylidene ligand, an alkylidyne ligand, and two other ligands of which at least one ligand is sufficiently electron withdrawing to render the rhenium atom significantly active for metathesis.

Abstract: This invention relates to a process for the concurrent isomerization and disproportionation of hydrocarbon olefins by contacting said hydrocarbon at disproportionation conditions with a catalyst comprising an inorganic oxide matrix, a ferrierite compound, and a heavy metal selected from the group consisting of molybdenum, tungsten, rhenium and mixtures thereof.

Abstract: Propylene is produced from the disproportionation of impure butene-2 containing oxygen-ates and butene-1 by treatment with alumina and isomerization of the butene-1 prior to disproportionation with ethylene.

Abstract: The invention discloses that hydrocarbon lubricants containing olefinic unsaturation participate in an olefin metathesis reaction with alkenes containing polar functional groups to provide an equilibrium mixture containing hydrocarbon lubricants containing the polar groups of the alkenes. The discovery is particularly applicable to the functionalization of near linear lubricants prepared from the oligomerization of propylene using surface deactivated zeolite or lubricants prepared by the oligomerization of C.sub.6 -C.sub.20 alpha olefins using coordination catalyst. Functionalized groups can be incorporated that impart a wide range of properties to the lubricant such as anti-wear or anti-corrosion resistance, or improve the compatibility of the lubricant with other additives.

Abstract: This invention relates to a two step process for converting linear paraffins to alpha olefins. The first step comprises contacting said paraffins with a catalyst comprising an oxide an alkali or alkaline earth metal optionally dispersed on a refractory and porous carrier. The product of this process contains only small amounts of aromatics and branched olefins. The cracked product is then converted to an olefin product containing primarily alph olefins by contacting with ethylene and a disproportionation catalyst as disproportionation conditions.

Abstract: This invention relates to a process for the purification of an alpha olefinic feedstock contaminated with internal olefins which process comprises contacting said alpha olefinic feedstock with ethylene in the presence of a catalyst comprising an organoborane promoted alkali metal doped molybdenum and/or rhenium oxide supported on an inorganic oxide support.

Abstract: This invention relates to a process for the concurrent isomerization and disproportionation of hydrocarbon olefins by contacting said hydrocarbon at disporportionation conditions with a catalyst comprising a physical mixture of a disproportionation catalyst comprising a heavy metal selected from the group consisting of molybdenum, tungsten, rhenium and mixtures thereof, deposited on an inorganic oxide support and a double bond isomerization catalyst comprising an acidic zeolite capable of effecting double bond isomerization.

Abstract: A process is disclosed for the preparation of low viscosity lubricant range hydrocarbons having high viscosity index which comprises: contacting olefinic dimer, or mixtures thereof, with a Group 6 metal oxide disproportionation catalyst on a solid support under disproportionation reaction conditions. The dimer comprises the product of the oligomerization of C.sub.6 -C.sub.20 alpha-olefins in contact with reduced chromium oxide catalyst on silica support. The disproportionation catalyst preparation includes treatment by oxidation at a temperature of 200.degree. C. to 900.degree. C. in the presence of an oxidizing gas and then treatment with a reducing agent at a temperature and a time sufficient to reduce said catalyst. The disproportionation reaction effluent is separated and lubricant range hydrocarbons recovered. The preferred disproportionation catalyst for the process is reduced tungsten oxide on silica support.

Abstract: Non-conjugated diolefins having the formula: ##STR1## wherein R.sup.3 and R.sup.4 are either hydrogen, alkyl or substituted alkyl and n is an integer,are produced by the process comprising reacting a diolefin having the formula: ##STR2## wherein R.sup.3 and R.sup.4 and n are the same as in formula (I) and R.sup.1 and R.sup.2 are either hydrogen, alkyl or substituted alkyl,with ethylene in the presence of a disproportionation catalyst comprising supported rhenium heptoxide and a promoter comprising either a tetraalkyl tin compound or a trialkyl aluminium compound.

Abstract: This invention relates to a process for the concurrent isomerization and disproportionation of hydrocarbon olefins by contacting said hydrocarbon at disproportionation conditions with a catalyst prepared by incorporating a ferrierite compound and a metals solution containing cobalt and an element selected from the group consisting of molybdenum and tungsten into an alumina hydrogel.

Abstract: This invention relates to a process for disproportionation of hydrocarbon olefins by contacting said hydrocarbon at disproportionation conditions with a catalyst prepared by incorporating a metals solution containing cobalt, an element selected from the group consisting of molybdenum, tungsten and mixtures thereof, and a phosphorus-containing compound, into an alumina hydrogel.

Abstract: This invention relates to a process for disproportionation of hydrocarbon olefins by contacting said hydrocarbon at disproportionation conditions with a catalyst prepared by incorporating a metals solution containing cobalt and an element selected from the group consisting of molybdenum, tungsten and mixtures thereof, and a phosphorus-containing compound into an alumina hydrogel. The final calcined catalysts have surface areas greater than about 225 m.sup.2 /g and more than about 50% of their pore volume in pores having diameters less than about 70 .ANG..

Abstract: 1. A catalyst system for olefin disproportionation containing molybdenum oxide supported on alumina prepared by a process which comprises:(a) comulling a gamma alumina providing agent with a sulfur-containing compound and/or a phosphorus-containing compound to produce a homogeneous mass,(b) extruding the mass and dividing it into small particles,(c) drying and calcining said particles at a temperature in the range of from about 400.degree. C. to about 800.degree. C.(d) subjecting said particles to at least one additional step comprising: (1) impregnating said particles with a solution of molybdenum oxide(s), (2) drying and (3) calcining said impregnated particles at a temperature in the range of from about 400.degree. C. to about 800.degree. C.

Abstract: A catalyst system for olefin disproportionation containing molebdenum oxide supported on alumina prepared by a process which comprises:(a) comulling a gamma alumina providing agent with a sulfur-containing compound and/or a phosphorus-containing compound to produce a homogeneous mass,(b) extruding the mass and dividing it into small particles,(c) drying and calcining said particles at a temperature in the range of from about 400.degree. C. to about 800.degree. C.(d) subjecting said particles to at least one additional step comprising: (1) impregnating said particles with a solution of molybdenum oxide(s), (2) drying and (3) calcining said impregnated particles at a temperature in the range of from about 400.degree. C. to about 800.degree. C.

Abstract: Improved catalytic systems of long active duration, comprising initially (a) a tungsten compound, (b) an organometallic compound and (c) a partially or totally fluorinated organic compound.Process of stabilization of these catalytic systems, comprising dissolving (a) in an organic solvent, contacting (b) with (a), agitation and heating at 0.degree. to 100.degree. C. for 0.5 to 60 minutes, then introduction of (c) into the mixture of (a) and (b).Use of these stabilised catalytic systems for the metathesis of olefins which carry functional groups or do not carry such groups.