Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
  • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/56—Platinum group metals
  • B01J23/58—Platinum group metals with alkali- or alkaline earth metals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0201—Impregnation
  • B01J37/0211—Impregnation using a colloidal suspension
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/06—Washing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/16—Reducing
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
  • C10G45/32—Selective hydrogenation of the diolefin or acetylene compounds
  • C10G45/34—Selective hydrogenation of the diolefin or acetylene compounds characterised by the catalyst used
  • C10G45/40—Selective hydrogenation of the diolefin or acetylene compounds characterised by the catalyst used containing platinum group metals or compounds thereof
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
  • C10G45/58—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins
  • C10G45/60—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins characterised by the catalyst used
  • C10G45/62—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins characterised by the catalyst used containing platinum group metals or compounds thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
  • B01J35/391—Physical properties of the active metal ingredient
  • B01J35/394—Metal dispersion value, e.g. percentage or fraction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
  • B01J35/396—Distribution of the active metal ingredient
  • B01J35/397—Egg shell like
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/613—10-100 m2/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/615—100-500 m2/g

Definitions

• the selective hydrogenation process makes it possible to convert the polyunsaturated compounds of the petroleum fractions by conversion of the most unsaturated compounds to the corresponding alkenes, avoiding total saturation and thus the formation of the corresponding alkanes.
• the object of the invention is to provide an improved performance catalyst and a process for the selective hydrogenation of the unsaturated hydrocarbon compounds present in the hydrocarbon cuts, preferably cuts from steam cracking or catalytic cracking.
• the catalysts for selective hydrogenation of these sections are often palladium-based, in the form of small metal particles deposited on a support which may be a refractory oxide in the form of beads, extrusions, trilobates or in forms having other geometries.
• the palladium content and the size of the palladium particles are among the criteria that have an importance on the activity and the selectivity of the catalysts.
• the macroscopic distribution of the metal particles in the support is also an important criterion, mainly in the context of rapid and consecutive reactions such as selective hydrogenations. These elements generally need to be in a crust at the periphery of the support in order to avoid problems of intragranular material transfer that can lead to defects in activity and a loss of selectivity.
• the present invention aims to obtain catalysts having a catalytic activity greater than that of the catalysts of the prior art.
• the catalysts according to the invention comprise inter alia a crust formed by the palladium particles. They have palladium dispersions of between 25 and 70% and densities of palladium particles of between 1500 and 4100 Palladium particles per ⁇ m 2 (denoted as Pd / ⁇ m 2 ). They further comprise an alkaline or alkaline earth compound homogeneously distributed within the support grain.
• the density of palladium particles in the prior art is calculated for catalysts in which the palladium is distributed in crust.
• US5929261 describes catalysts comprising a crust of up to 5 ⁇ m of metals. These catalysts are obtained by impregnation or spraying (spraying according to the Anglo-Saxon terminology) of metal floors on hot substrates.
• the catalyst of Example 1 is a palladium on alumina catalyst comprising 0.05% by weight of palladium, the BET surface area of the alumina being 290 m 2 / g.
• the sizes of palladium particles are between 2 and 4 nm and the alumina spheres have a diameter of between 1.5 and 4 mm. This results in a palladium particle density of between 200 and 6600 Pd / ⁇ m 2 particles.
• US4484015 describes among others palladium monometallic catalysts comprising a crust of 300 microns palladium.
• Example 1 corresponds to a catalyst comprising 0.017% by weight of palladium.
• This catalyst is obtained by impregnation of an acid solution of palladium on spheres of alumina alpha 6 m 2 / g and 4 mm diameter.
• the nanoparticles of Pd have sizes of between 2.5 and 4 mm. It follows from Palladium particle density of between 170 and 750 Pd / ⁇ m 2 particles.
• Example 1 corresponds to the preparation of a monometallic catalyst comprising 0.35% by weight of palladium. The preparation is carried out by impregnation of a solution of palladium nitrate on alumina beads having a BET surface area of 35 m 2 / g and a mean diameter of 3 mm. According to the method of preparation employed, the palladium nanoparticles have sizes of between 4 and 4.5 mm. This results in a palladium particle density of between 150 and 250 Pd / ⁇ m 2 particles.
• the invention relates to a catalyst comprising a porous carrier, palladium, at least one metal selected from the group consisting of alkali and alkaline earth metal in which:
• the specific surface area of the porous support is between 50 and 210 m 2 / g
• the palladium content in the catalyst is between 0.05 and 2% by weight, at least 80% by weight of Palladium is distributed in a crust; at the periphery of the support, the thickness of said crust being between 20 and 200 ⁇ m, the metal dispersion D is between 25% and 70%,
• the palladium particle density in the crust is between 1500 and 4100 palladium particles per .mu.m.sup.2
• the invention also relates to the preparation of the catalyst and its use in selective hydrogenation.
• the present invention relates to catalysts having improved catalytic activity.
• At least one metal selected from the group consisting of alkalis and alkaline earths
• porous support comprising at least one refractory oxide selected from the group consisting of silica, alumina and silica-alumina, very preferably the porous support is alumina, in which:
• the specific surface area of the porous support is between 50 and 210 m 2 / g, preferably between 100 and 160 m 2 / g, very preferably between 120 and
• the palladium content in the catalyst is between 0.05 and 2% by weight, preferably between 0.1 and 0.8% by weight.
• At least 80% by weight of Palladium is distributed in a crust at the periphery of the support, the thickness of said crust being between 20 and 200 ⁇ m, preferably between 20 and 120 ⁇ m, very preferably between 20 and 110 ⁇ m.
• the metal dispersion D is between 25% and 70%, preferably between 35% and 60%
• the density of palladium particles in the crust denoted De is between 1500 and 4100 palladium particles per ⁇ m 2 , preferably between 1550 and 4000 palladium particles per ⁇ m 2 , preferably comprised between between 1600 and 3950 palladium particles per ⁇ m 2 the sum of the contents of alkali and / or alkaline earth metals in the catalyst is between 0.05 and 5% by weight, more preferably between 0.1 and 2% by weight.
• the alkali metal and / or alkaline earth metal is homogeneously distributed through the support with a coefficient R (defined in the rest of the text) of between 0.8 and 1.2.
• the porous support is advantageously in the form of balls, trilobes, extrudates, pellets, or irregular and non-spherical agglomerates, the specific shape of which may result from a crushing step.
• said support is in the form of balls or extrudates.
• said support is in the form of beads.
• the pore volume of the support is generally between 0.1 and 1.5 cm 3 / g, preferably between 0.5 and 1.3 cm 3 / g.
• the alkali metal is generally selected from the group consisting of lithium, sodium, potassium, rubidium and cesium, preferably lithium, sodium and potassium, very preferably sodium and potassium. Even more preferably, the alkali metal is sodium.
• the alkaline earth metal is generally selected from the group consisting of magnesium, calcium, strontium and barium, preferably magnesium and calcium, most preferably magnesium.
• the alkali metal when present, is homogeneously distributed through the support with a coefficient R of between 0.8 and 1.2.
• the alkaline earth metal when present, is homogeneously distributed through the support with a coefficient R between 0.8 and 1.2. Definition of coefficient R
• the distribution profiles of the elements within the catalyst grains are obtained by a Castaing microprobe. At least 30 points of analysis are carried out along the diameter of the ball or extrusion at a rate of about ten points on the crust of the active element (here palladium) and about ten points grain center. This gives the distribution profile c (x) for xe [-r; + r] with c the local concentration of the element, r the radius of the ball or extrusion and x the position of the point of analyzes along the grain diameter in relation to the center of this grain.
• Figure 1 shows an example of profile obtained.
• the distribution of the elements is characterized by a dimensionless R coefficient weighting the local concentration by a weight increasing according to the position on the diameter.
• an element whose concentration is uniform has a coefficient R equal to 1
• a dome-deposited element concentration at the core greater than the concentration at the edges of the support
• a crust-distributed element concentration at edges larger than the concentration in the core of the support
• Castaing microprobe analysis gives the values of the concentrations in a finite number of values of x, R is thus evaluated numerically by integration methods well known to those skilled in the art. Preferably, R is determined by the trapezoidal method.
• the distribution of the alkaline element is defined as homogeneous when the distribution coefficient R defined above is between 0.8 and 1.2.
• the distribution of the alkaline earth element is defined as homogeneous when the distribution coefficient R defined above is between 0.8 and 1.2.
• the crustal thickness is defined as the distance to the edge of the grain containing 80% of the element.
• the cumulative quantity Q (y) of the element in the grain is calculated as a function of the distance y at the edge of the grain.
• Figure 2 shows an example of cumulated amount.
• the density of palladium particles is named De.
• Measurements of metal dispersions are carried out by chemisorption of carbon monoxide CO, on the previously reduced catalyst under 1 liter of hydrogen per hour and per gram of catalyst, with a temperature rise of 300 ° C./h and a plateau of two hours at 150 ° C. The catalyst is then flushed for 1 hour at 150 ° C. under helium and then cooled to 25 ° C. under helium.
• the chemisorption of CO is carried out at 25 ° C. in a dynamic manner according to the usual practices known to those skilled in the art, it leads to a chemisorbed volume of CO, from which the person skilled in the art can calculate the number of chemisorbed CO molecules. .
• a stoichiometric ratio of one CO molecule per atom of surface Pd is taken into account to calculate the number of surface Pd atoms.
• the dispersion is expressed as% of surface Pd atoms relative to all the Pd atoms present in the catalyst sample.
• the average size of the crystallites is deduced from these dispersion measurements, by applying the dispersion-particle size relationships known to those skilled in the art and described in "Physico-chemical analysis of industrial catalysts, Chapter I 1 Technip Publishing, Paris 2001” .
• the number of Pd atoms per metal particle as a function of particle size is determined by the Van Hardeveld and Hartog model (R. Van Hardeveld, F. Hartog, Surf ScL, 15 (1969) 189).
• N a Number of Avogadro (6,022.10 23 atoms / mole)
• Mp d Molar mass of palladium (106.42 g / mol)
• n Pd number of palladium atoms per palladium particle.
• V t Total volume of the support ball in mm 3
• V t 4 / 3.TTr 3 (where r is the radius of the ball)
• V c Volume of the crust in mm 3
• V 0 V t - 4 / 3. ⁇ . (Re) 3 (e being the thickness of the crust)
• the invention also relates to a process for preparing the catalyst comprising the following steps:
• a step a) of preparing in an apparatus a colloidal suspension of palladium oxide or of palladium hydroxide in aqueous phase by mixing an aqueous solution 1 comprising at least one hydroxide selected from the group consisting of hydroxides alkaline and alkaline earth hydroxides and an aqueous solution 2 comprising at least one palladium precursor salt, the solution 2 and then the solution 1 being poured into the apparatus or solutions 1 and 2 being poured simultaneously into the apparatus, the preparation temperature being between 5 ° C and 40 ° C, the pH of said colloidal suspension being between 1.0 and 3.5, the residence time of said colloidal suspension in the apparatus being comprised between 0 and 20 hours.
• a step c) of preparing a catalyst precursor by maturation between 0.5 and 40 hours of said impregnated support is a step c) of preparing a catalyst precursor by maturation between 0.5 and 40 hours of said impregnated support.
• the pH, the residence time of the colloidal suspension and the specific surface of the support are set in their respective intervals.
• the palladium content of between 0.05 and 2% by weight is then adjusted in order to obtain a density of palladium particles in the crust of between 1500 and 4100 palladium particles per ⁇ m 2 .
• the palladium content of between 0.05 and 2% by weight, the residence time of the colloidal suspension and the specific surface area of the support are set in their respective ranges.
• the pH is then adjusted to obtain a density of palladium particles in the crust of between 1500 and 4100 palladium particles per ⁇ m 2 .
• the colloidal suspension is generally obtained by hydrolysis of the palladium cation in an aqueous medium, which leads to the formation of particles of oxides or hydroxides of palladium in suspension.
• the aqueous solution of alkali metal hydroxides or alkaline earth hydroxides is generally selected from the group consisting of aqueous solutions of sodium hydroxide, aqueous solutions of magnesium hydroxide, even more preferably, it is an aqueous solution of sodium hydroxide.
• the precursor salt of palladium is generally selected from the group consisting of palladium chloride, palladium nitrate and palladium sulfate. Very preferably, the precursor salt of palladium is palladium nitrate.
• the aqueous solution 2 comprising at least one palladium precursor salt and then the aqueous solution 1 comprising at least one alkali or alkaline earth hydroxide are generally poured into the apparatus. Solutions 1 and 2 can be poured simultaneously into the equipment. Preferably, the aqueous solution 2 and then the aqueous solution 1 are poured into the apparatus.
• the colloidal suspension generally remains in the apparatus for a residence time of between 0 and 20 hours.
• the pH of the colloidal suspension can be modified during this residence time by adding amounts of acid or base compatible with the stability of the colloidal suspension.
• the preparation temperature is between 5 ° C. and 40 ° C. and preferably between 15 ° C. and 35 ° C.
• the palladium concentration is preferably between 5 and 150 millimoles per liter, more preferably between 8 and 80 millimoles per liter.
• step b) depositing the colloidal suspension prepared in step a) by impregnation on a support, preferably on alumina
• the colloidal suspension prepared in step a) is then impregnated on a support.
• the support may optionally undergo a set of treatments before the impregnation step, such as calcinations or hydrations.
• the support may also already comprise one or more metal elements before the impregnation of the colloidal suspension.
• Metal elements may also be introduced into the colloidal suspension. These metal elements can be introduced either by conventional techniques or by using the method according to the present invention.
• the colloidal suspension is preferably poured onto the support. This process can be carried out either discontinuously, that is to say that the step of preparation of the colloidal suspension precedes the impregnation step on the support and that most of the colloidal suspension is sent in a only once to the impregnation stage, either continuously, that is to say that the product obtained in step a) is sent continuously after adjusting the residence time of the colloidal suspension in step b ).
• a process may be cited as a continuous process, in which solutions 1 and 2 are poured simultaneously into a tank which flows continuously into an area comprising the support to be impregnated.
• step b) maturation of the impregnated support during step b) for a period of between 0.5 and 40 hours
• the impregnated support is generally wet-aged for 0.5 to 40 hours, preferably for 1 to 30 hours.
• the precursor of the catalyst is generally dried in order to eliminate all or part of the water introduced during the impregnation, preferably at a temperature of between 50 and 25 ° C., more preferably between 70 ° C. and 200 ° C. vs.
• the drying is generally carried out under combustion air of a hydrocarbon, preferably methane, or in heated air comprising between 0 and 80 grams of water per kilogram of combustion air, an oxygen content of between 5% and 25% volume and a carbon dioxide content between 0% and 10% volume.
• the catalyst is generally calcined in combustion air, preferably a methane combustion air comprising between 40 and 80 grams of water per kg of combustion air, an oxygen content of between 5% and 15% by volume. and a CO2 level between 4% and 10% volume.
• the calcination temperature is generally between 250 ° C. and 900 ° C., preferably between about 300 ° C. and about 500 ° C.
• the calcination time is generally between 0.5 hours and 5 hours.
• step f) reducing the oxide thus supported obtained in step e), preferably using hydrogen gas.
• the catalyst is generally reduced.
• This step is preferably carried out in the presence of a reducing gas, either in situ, that is to say in the reactor where the catalytic conversion is carried out, or ex-situ.
• this step is carried out at a temperature of between 80 ° C. and 180 ° C., even more preferably between 100 ° C. and 160 ° C.
• the reduction is carried out in the presence of a reducing gas comprising between 25 vol% and 100 vol% of hydrogen, preferably 100% of hydrogen.
• the hydrogen is optionally supplemented with an inert gas for reduction, preferably argon, nitrogen or methane.
• the reduction generally comprises a temperature rise phase and then a landing.
• the duration of the reduction stage is generally between 1 and 10 hours, preferably between 2 and 8 hours.
• the WH is generally between 150 and 1000, preferably between 300 and 900 liters of reducing gas per hour and per liter of catalyst.
• the catalyst may contain one or more promoter metals.
• the promoter metal or metals may be introduced during the preparation of the support, on the support already formed, during step a) or after steps b) c) d) e) or f).
• the invention also relates to the catalyst obtained from the catalyst preparation processes described in the present invention.
• the catalyst according to the invention can be used in processes involving transformation of organic compounds.
• the catalyst according to the invention can be used in processes comprising hydrogenation reactions of the compounds comprising aromatic functions, ketones, aldehydes, acids or nitro, the hydrogenation of carbon monoxide in C1-C6 alcohols, in methanol. or in dimethyl ether, isomerization or hydroisomerization reactions, hydrogenolysis reactions, and, in general, reactions involving carbon-carbon cleavage or formation.
• the operating conditions generally used for these reactions are the following: a temperature of between 0 ° C. and 500 ° C., preferably between 25 ° and 350 ° C., a pressure of between 0.1 and 20 MPa, preferably between 0.1. and 10 MPa, a hourly volume velocity (VVH) between 0.1 and 50 h -1 , preferably between 0.5 and 20 h -1 for a liquid feed, and between 500 and 30 000 h -1 , preferably between 500 and 15,000 h -1 for a gaseous charge.
• VVH hourly volume velocity
• the molar ratio of hydrogen to feedstock is between 1 and 500 liters per liter, preferably between 10 and 150 liters per liter.
• the catalyst according to the invention can also be used in the hydrogenation reactions of compounds comprising acetylenic, diene and olefinic functions.
• the invention also relates to the method of selective hydrogenation by placing a filler on contact with the catalyst according to the invention or on the catalyst prepared according to the invention, said filler being selected from the group consisting of C3 steam cracking cuts. , C4 steam cracking cups, C5 steam cracking cups and steam cracking gasolines also known as pyrolysis gasolines.
• the catalysts according to the invention are used for the reactions of selective hydrogenation of polyunsaturated hydrocarbon fractions resulting from steam cracking and / or catalytic cracking, preferably polyunsaturated hydrocarbon cuts. from steam cracking.
• hydrocarbon conversion processes such as steam cracking or catalytic cracking are operated at high temperature and produce a wide variety of unsaturated molecules such as ethylene, propylene, butenes linear, isobutene, pentenes as well as unsaturated molecules containing up to about 15 carbon atoms.
• polyunsaturated compounds acetylene, propadiene and methylacetylene (or propyne), 1-2 and 1-3 butadiene, vinylacetylene and ethylacetylene, and other polyunsaturated compounds whose boiling point corresponds to the essence fraction C5 + .
• the C3 steam cracking cut can have the following average composition: of the order of 90% by weight propylene, of the order of 3 to 8% by weight of propadiene and methylacetylene, the remainder being essentially propane. In some C3 cuts, between 0.1 and 2% by weight of C2 and C4 may also be present.
• the specifications for the concentrations of these polyunsaturated compounds for petrochemical and polymerization units are very low: 20-30 ppm by weight of MAPD (MethylAcetylene and PropaDiene) for propylene chemical grade and less than 10 ppm by weight or up to 1 ppm weight for the quality "polymerization".
• MAPD MetalAcetylene and PropaDiene
• a steam cracking C4 cut has, for example, the following average molar composition: 1% butane, 46.5% butene, 51% butadiene, 1.3% vinylacetylene (VAC) and 0.2% butyne.
• VAC vinylacetylene
• C4 cuts between 0.1 and 2% by weight of C3 and C5 may also be present. Again the specifications are severe: diolefin content strictly less than 10 ppm weight for a C4 cut that will be used in petrochemical or polymerization.
• a C5 steam cracking cut has, for example, the following mass-average composition: 21% of pentanes, 45% of pentenes and 34% of pentadienes.
• the selective hydrogenation process has progressively imposed itself to eliminate the polyunsaturated compounds of the C3 to C5 petroleum fractions mentioned, because this process allows the conversion of the most unsaturated compounds to the alkenes. corresponding by avoiding total saturation and thus the formation of the corresponding alkanes.
• the selective hydrogenation can be carried out in the gas or liquid phase, preferably in the liquid phase.
• a reaction in the liquid phase makes it possible to lower the energy cost and to increase the cycle time of the catalysts.
• the pressure is generally between 1 and 3 MPa, the temperature between 2 and 50 ° C. and the molar ratio hydrogen / (polyunsaturated compounds to be hydrogenated) between 0.1 and 4, preferably between 1 and 2.
• the pressure is generally between 1 and 3 MPa, the temperature between 40 and 120 ° C. and the molar ratio hydrogen / (polyunsaturated compounds to be hydrogenated) between 0.1 and 4, preferably between 1 and 2.
• Steam cracking produces mainly ethylene, propylene, a C4 cut and steam cracking gasoline also known as pyrolysis gasoline.
• the charge is a pyrolysis gasoline.
• the pyrolysis gasoline corresponds to a section whose boiling point is generally between 0 ° C. and 250 ° C., preferably between 10 ° C. and 220 ° C.
• This charge generally comprises the C5-C12 cut with traces. of C3, C4, C13, C14, C15 (for example between 0.1 to 3% by weight for each of these cuts).
• a C5-200 ° C cut generally has a composition in% by weight as follows:
• Paraffins 8 - 12 Aromatic 58 - 62 Mono-olefins 8 - 10 Diolefins 18 - 22 Sulfur 20 - 300 ppm
• the selective hydrogenation of a pyrolysis gasoline consists of bringing the charge to be treated into contact with hydrogen introduced in excess into one or more reactors containing the hydrogenation catalyst.
• the hydrogen flow rate is adjusted in order to dispose of it in sufficient quantity to theoretically hydrogenate all the diolefins, acetylenics and alkenyl aromatics and to maintain an excess of hydrogen at the reactor outlet.
• the molar ratio of hydrogen / (polyunsaturated compounds to be hydrogenated) is generally between 1 and 2
• the temperature is generally between 40 ° C. and 200 ° C., preferably between At 50 and 180 ° C.
• the space hourly velocity (corresponding to the volume of hydrocarbon per volume of catalyst per hour) is generally between 0.5 h -1 and 10 h -1, preferably between 1 h -1 and 5 h -1.
• h-1 and the pressure is generally between 1.0 MPa and 6.5 MPa, preferably between 2.0 MPa and 3.5 MPa.
• An aqueous solution of palladium nitrate Pd (N ⁇ 3 ) 2 is prepared at 25 ° C. by diluting 3.5 g of a solution of palladium nitrate Pd (NOa) 2 containing 8.5% by weight of palladium, with demineralized water to a volume that corresponds to the pore volume of the alumina support.
• the pH of the solution is 0.7.
• This solution is then impregnated on 100 gram of an ⁇ -Al 2 O 3 type alumina, the SBET of which is 130 m 2 / g.
• This alumina is in the form of beads whose average diameter is 3 mm.
• the catalyst A obtained is dried under air at 120 ° C. and is then calcined for 2 hours at 450 ° C. under a combustion air flow with a WH of 500 liters of combustion air per liter of catalyst per hour.
• the combustion air contains about 60 g of water per kg of air, 10% by volume of oxygen and 7% by volume of carbon dioxide.
• Catalyst A contains 0.3% Pd.
• the characterization of the catalyst by a microprobe of Castaing leads to 80% of the Pd located in a crust with a thickness of 250 ⁇ m.
• the catalyst Before the chemisorption of CO and the catalytic test, the catalyst is finally reduced under a hydrogen flow of WH 500 liters of hydrogen per liter of catalyst per hour, with a temperature rise rate of 300 ° C./h and a plateau at 150 ° C for 2 hours.
• the volume of chemisorbed CO is 0.365 ml / g, ie a metal dispersion of 53%, which corresponds to an average particle size of 2.3 nm, ie 440 Pd atoms / particle.
• Example 2a (non-compliant catalyst Ba)
• the residence time of the colloidal suspension in the apparatus before impregnation is 15 minutes for Examples 2a, 2b and 3 which follow.
• a colloidal suspension of Pd oxide is prepared with stirring at 25 ° C. by diluting 3.5 g of a solution of palladium nitrate Pd (NOa) 2 containing 8.5% by weight of palladium Pd with approximately 20 ml of demineralized water, then add about 10 ml of a sodium hydroxide solution to reach a pH of 1, 6. The suspension is then diluted with deionized water to a volume which corresponds to the pore volume of the alumina support.
• NOa palladium nitrate Pd
• This solution is then impregnated on 59 g of an alumina of type ⁇ -AI 2 O 3 whose S B ET is 130 m 2 / g.
• This alumina is in the form of beads whose average diameter is 3 mm.
• the catalyst Ba obtained is dried under air at a WH of 500 liters of air per liter of catalyst per hour, with a temperature rise of 25 ° C. to 120 ° C. for 8 hours, followed by a 2 hour stage. at 120 ° C.
• the catalyst is then calcined under a flow of combustion air at a WH of 500 liters of combustion air per liter of catalyst per hour, with a temperature rise rate of approximately 300 ° C. per hour followed by a 2 hour stage at 450 ° C.
• the combustion air contains approximately 60 g of water per kg of air, 10% by volume of oxygen and 7% by volume of carbon dioxide .
• Catalyst Ba contains 0.5% Pd.
• the characterization of the catalyst by a Castaing microprobe makes it possible to calculate a crust with a thickness of approximately 91 ⁇ m.
• R (Na) OJ, which indicates a non-homogeneous distribution of sodium.
• the catalyst is finally reduced under a hydrogen flow of WH 500 liters of hydrogen per liter of catalyst per hour, with a temperature rise rate of 300 ° C./h and a plateau at 150 0 C for 2 hours.
• the volume of chemisorbed CO is 0.583 ml / g, ie a metal dispersion of 51%, which corresponds to a particle size of approximately 2.4 nm, ie 490 Pd atoms / particle.
• a colloidal suspension of Pd oxide is prepared with stirring at 25 ° C. by diluting 3.5 g of a solution of palladium nitrate Pd (N ⁇ 3 ) 2 containing 8.5% by weight of Pd palladium with about 10 ml of demineralised water, then added to about 20 ml of a sodium hydroxide solution to reach a pH of 12.1. The suspension is then diluted with deionized water to a volume which corresponds to the pore volume of the alumina support.
• This solution is then impregnated on 59 g of an ⁇ -Al 2 O 3 type alumina, the SB E T of which is 130 m 2 / g.
• This alumina is in the form of beads whose average diameter is 3 mm.
• the catalyst Bb obtained is dried under air at a WH of 500 liters of air per liter of catalyst per hour, with a temperature rise of 25 ° C. to 120 ° C. for 8 hours, followed by a 2 hour stage at 12O 0 C.
• the catalyst is then calcined under a flow of combustion air at a WH of 500 liters of combustion air per liter of catalyst and per hour, with a rate of rise in temperature of about 300 ° C. per hour, followed by a plateau of 2 hours at 450 ° C.
• the combustion air contains about 60 g of water per kg of air, 10% by volume of oxygen and 7% by volume of carbon dioxide.
• Catalyst Bb contains 0.5% Pd.
• the catalyst Before the chemisorption of CO and the catalytic test, the catalyst is finally reduced under a hydrogen flow of WH 500 liters of hydrogen per liter of catalyst per hour, with a temperature rise rate of 300 ° C./h and a plateau at 150 ° C for 2 hours.
• the volume of chemisorbed CO is 0.551 ml / g, ie a metal dispersion of 48%, which corresponds to a particle size of approximately 2.5 nm, ie approximately 536 Pd atoms / particle.
• a colloidal suspension of Pd oxide is prepared with stirring at 25 ° C. by diluting 3.5 g of a solution of palladium nitrate Pd (NOa) 2 containing 8.5% by weight of palladium Pd with approximately 20 ml of demineralized water, then adding about 10 ml of a sodium hydroxide solution to reach a pH of 1.7. The suspension is then diluted with demineralized water to a volume which corresponds to the pore volume of 59 g of the alumina support.
• NOa palladium nitrate Pd
• This solution is then impregnated on 59 g of an alumina of type ⁇ -AI 2 O 3 whose S B ET is 130 m 2 / g.
• This alumina is in the form of beads whose average diameter is 3 mm.
• a step of maturation of the impregnated support before drying for a period of 20 hours is carried out under air in a confined and humid environment.
• the catalyst C obtained is dried in air at a WH of 500 liters of air per liter of catalyst per hour, with a temperature rise of 25 ° C. to 120 ° C. for 8 hours, followed by a plateau of 2 hours. at 120 ° C.
• the catalyst is then calcined under a flow of combustion air at a WH of 500 liters of combustion air per liter of catalyst per hour, with a temperature rise rate of approximately 300 ° C. per hour followed by a 2 hour stage at 450 ° C.
• the combustion air contains approximately 60 g of water per kg of air, 10% by volume of oxygen and 7% by volume of carbon dioxide .
• Catalyst C contains 0.5% Pd.
• the characterization of the catalyst by a Castaing microprobe leads to 80% Pd on a crust with a thickness of approximately 75 ⁇ m.
• the catalyst Before the chemisorption of CO and the catalytic test, the catalyst is finally reduced under a hydrogen flow of WH 500 liters of hydrogen per liter of catalyst per hour, with a temperature rise rate of 300 ° C./h and a plateau at 150 ° C for 2 hours.
• the volume of chemisorbed CO is 0.576 ml / g, ie a metal dispersion of 50%, which corresponds to a particle size of approximately 2.4 nm, ie approximately 490 Pd atoms / particle.
• Example 4 Catalytic Test in Hydrogenation of a Styrene-Isoprene Mixture in the Presence of S.
• the catalysts are then subjected to a hydrogenation test in a perfectly stirred batch reactor of the "Grignard" type. To do this, the reduced catalyst balls are fixed in the air protected in an annular basket located around the stirring device.
• the baskets used in the reactors are Robinson Mahonnay type.
• the hydrogenation is carried out in the liquid phase.
• composition of the filler is as follows: 8% styrene weight, 8% isoprene weight, 10 ppm S introduced as pentanethiol, 100 ppm S introduced as thiophene, the solvent being n-heptane.
• the test is carried out under a constant pressure of 3.5 MPa of hydrogen and at a temperature of 45 ° C.
• the products of the reaction are analyzed by gas chromatography.
• the catalytic activities are expressed in moles of H 2 consumed per minute and per mole of accessible Pd and are reported in Table 1.
• Catalysts Ba and Bb which have a particle density of Pd within the defined range have a substantially higher intrinsic catalytic activity than Catalyst A whose Pd particle density is lower than the defined range.
• Catalyst C which has both a density within the defined range and a homogeneous distribution of Na within the bead has a catalytic activity substantially greater than the activity of catalysts Ba and Bb whose particle density is within the defined range but whose distribution of Na is not homogeneous within the catalyst ball.
• the residence time of the colloidal suspension in the equipment before impregnation is 30 minutes for Examples 5 to 8.
• a colloidal suspension of Pd oxide is prepared with stirring at 25 ° C. by diluting 0.58 g of a solution of palladium nitrate Pd (NU 3 ) 2 containing 8.5% by weight of palladium Pd with approximately 35 ml. demineralized water, then add about 10 ml of a sodium hydroxide solution to reach a pH of 2.3. Suspension is then diluted with deionized water to a volume which corresponds to the pore volume of the alumina support.
• This solution is then impregnated on 90 g of an ⁇ -Al 2 O 3 type alumina, the S BET of which is 130 m 2 / g.
• This alumina is in the form of beads whose average diameter is 3 mm.
• a step of maturation of the impregnated support before drying for a period of 20 hours is carried out under air in a confined and humid environment.
• the catalyst D obtained is dried in air at a WH of 500 liters of air per liter of catalyst per hour, with a temperature rise of 25 ° C. to 120 ° C. for 8 hours, followed by a plateau of 2 hours. at 120 ° C.
• the catalyst is then calcined under a flow of combustion air at a WH of 500 liters of combustion air per liter of catalyst per hour, with a temperature rise rate of approximately 300 ° C. per hour, followed by 2 hours at 450 ° C.
• the combustion air contains about 60 g of water per kg of air, 10% by volume of oxygen and 7% by volume of carbon dioxide.
• Catalyst D contains 0.055% Pd.
• the characterization of the catalyst by a Castaing microprobe shows that 80% of the Pd is distributed over a crust with a thickness of approximately 27 ⁇ m.
• the catalyst Before the chemisorption of CO and the catalytic test, the catalyst is finally reduced under a hydrogen flow of WH 500 liters of hydrogen per liter of catalyst per hour, with a temperature rise rate of 300 ° C./h and a bearing at 15O 0 C for 2 hours.
• the volume of chemisorbed CO is 0.071 ml / g, ie a metal dispersion of 56%, which corresponds to a particle size of approximately 2.1 nm, ie 340 Pd atoms / particles.
• a colloidal suspension of Pd oxide is prepared with stirring at 25 ° C. by diluting 1. 16 g of a solution of palladium nitrate Pd (NOa) 2 containing 8.5% by weight of palladium Pd with approximately 40 ml of demineralized water, then adding about 10 ml of a sodium hydroxide solution to reach a pH of 2.3. The suspension is then diluted with deionized water to a volume which corresponds to the pore volume of the alumina support.
• NOa palladium nitrate Pd
• This solution is then impregnated on 102 g of a ⁇ -Al 2 O 3 type alumina whose SB E T is 130 m 2 / g.
• This alumina is in the form of beads whose average diameter is 3 mm.
• a step of maturation of the impregnated support before drying for a period of 20 hours is carried out under air in a confined and humid environment.
• the catalyst E obtained is dried in air at a WH of 500 liters of air per liter of catalyst per hour, with a temperature rise of 25 ° C. to 120 ° C. for 8 hours, followed by a 2 hour stage at 120 ° C.
• the catalyst is then calcined under a flow of combustion air at a WH of 500 liters of combustion air per liter of catalyst per hour, with a temperature rise rate of approximately 300 ° C. per hour, followed by a 2 hour stage at 45O 0 C.
• the combustion air contains approximately 60 g of water per kg of air, 10% by volume of oxygen and 7% by volume of carbon dioxide .
• Catalyst E contains 0.097% Pd.
• the characterization of the catalyst by a Castaing microprobe shows that 80% of the Pd is distributed over a crust with a thickness of approximately 30 ⁇ m.
• the catalyst Before the chemisorption of CO and the catalytic test, the catalyst is finally reduced under a hydrogen flow of WH 500 liters of hydrogen per liter of catalyst per hour, with a temperature rise rate of 300 ° C./h and a plateau at 150 0 C for 2 hours.
• the volume of chemisorbed CO is 0.127 ml / g, ie a metal dispersion of 57%, which corresponds to a particle size of about 2.1 nm, ie 340 Pd atoms / particles.
• a colloidal suspension of Pd oxide is prepared with stirring at 25 ° C. by dilution of 2.3 g of a solution of palladium nitrate Pd (NO 3 ) 2 containing 8.5% by weight of palladium Pd with approximately 45 ml. demineralized water, then add about 10 ml of a sodium hydroxide solution to reach a pH of 2.4. The suspension is then diluted with deionized water to a volume which corresponds to the pore volume of the alumina support.
• This solution is then impregnated on 111 g of an ⁇ -Al 2 O 3 type alumina, the S B ET of which is 130 m 2 / g.
• This alumina is in the form of beads whose average diameter is 3 mm.
• a step of maturation of the impregnated support before drying for a period of 20 hours is carried out under air in a confined and humid environment.
• the catalyst F obtained is dried under air at a WH of 500 liters of air per liter of catalyst per hour, with a temperature rise of 25 ° C. to 120 ° C. for 8 hours, followed by a plateau of 2 hours. at 120 ° C.
• the catalyst is then calcined under a flow of combustion air at a WH of 500 liters of combustion air per liter of catalyst per hour, with a temperature rise rate of approximately 300 ° C. per hour followed by a 2 hour stage at 450 ° C.
• the combustion air contains approximately 60 g of water per kg of air, 10% by volume of oxygen and 7% by volume of carbon dioxide .
• Catalyst F contains 0.176% Pd.
• the characterization of the catalyst by a Castaing microprobe shows that 80% of the Pd is distributed over a crust with a thickness of about 31 ⁇ m.
• the catalyst Before the chemisorption of CO and the catalytic test, the catalyst is finally reduced under a hydrogen flow of WH 500 liters of hydrogen per liter of catalyst per hour, with a temperature rise rate of 300 ° C./h and a plateau at 150 0 C for 2 hours.
• the volume of chemisorbed CO is 0.231 ml / g, ie a metal dispersion of 57%, which corresponds to a particle size of approximately 2.1 nm, ie 340 Pd atoms / particles.
• a colloidal suspension of Pd oxide is prepared with stirring at 25 ° C. by diluting 3.45 g of a solution of palladium nitrate Pd (NO 3 ) 2 containing 8.5% by weight of palladium Pd with approximately 55 ml. demineralized water, then add about 10 ml of a sodium hydroxide solution to reach a pH of 2.4. The suspension is then diluted with deionized water to a volume which corresponds to the pore volume of the alumina support.
• This solution is then impregnated on 133 g of a ⁇ -Al 2 O 3 type alumina, the S B ET of which is 130 m 2 / g.
• This alumina is in the form of beads whose average diameter is 3 mm.
• a step of maturation of the impregnated support before drying for a period of 20 hours is carried out under air in a confined and humid environment.
• the catalyst G obtained is dried under air at a WH of 500 liters of air per liter of catalyst per hour, with a rise in temperature of 25 ° C. to 120 ° C. for 8 hours, followed by a plateau of 2 hours. at 12O 0 C.
• the catalyst is then calcined under a flow of combustion air at a WH of 500 liters of combustion air per liter of catalyst per hour, with a temperature rise rate of approximately 300 ° C. per hour followed by a 2 hour stage at 450 ° C.
• the combustion air contains approximately 60 g of water per kg of air, 10% by volume of oxygen and 7% by volume of carbon dioxide .
• Catalyst G contains 0.22% Pd.
• the catalyst is finally reduced under a hydrogen flow of WH 500 liters of hydrogen per liter of catalyst per hour, with a temperature rise rate of 300 ° C./h and a plateau at 150 0 C for 2 hours.
• the volume of chemisorbed CO is 0.287 ml / g, ie a metal dispersion of 57%, which corresponds to a particle size of about 2.1 nm, ie 340 Pd atoms / particles.
• the catalysts are then subjected to a hydrogenation test in a perfectly stirred batch reactor of the "Grignard" type.
• the hydrogenation is carried out in the liquid phase.
• composition of the filler is 6.3% by weight of 1,3-butadiene, the solvent being n-heptane.
• the test is carried out under a constant pressure of 0.5 MPa of hydrogen and at a temperature of 5 ° C.
• the products of the reaction are analyzed by gas chromatography.
• the catalytic activities are expressed in moles of H 2 consumed per second and per mole of accessible Pd and are reported in Table 2.
• Catalysts E and F whose particle density is within the defined range, have an intrinsic catalytic activity greater than a factor of 2 in catalyst D, the Pd particle density of which is below the defined range, and greater than one factor 1, 5 to catalyst G whose particle density of Pd is greater than the defined range.

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