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  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
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  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0201—Impregnation
  • B01J37/0213—Preparation of the impregnating solution
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  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0236—Drying, e.g. preparing a suspension, adding a soluble salt and drying
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  • B01J37/06—Washing
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  • B01J37/16—Reducing
  • B01J37/18—Reducing with gases containing free hydrogen
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  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
  • C07C5/02—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by hydrogenation
  • C07C5/03—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by hydrogenation of non-aromatic carbon-to-carbon double bonds
  • C07C5/05—Partial hydrogenation
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  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C7/00—Purification; Separation; Use of additives
  • C07C7/148—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound
  • C07C7/163—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound by hydrogenation
• • 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
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  • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
  • B01J2235/30—Scanning electron microscopy; Transmission electron microscopy
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  • 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
  • B01J23/66—Silver or gold
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  • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
  • B01J35/51—Spheres
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  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/612—Surface area less than 10 m2/g
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  • B01J35/613—10-100 m2/g
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  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/633—Pore volume less than 0.5 ml/g
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  • B01J35/635—0.5-1.0 ml/g
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  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/638—Pore volume more than 1.0 ml/g
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  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
  • C07C2521/02—Boron or aluminium; Oxides or hydroxides thereof
  • C07C2521/04—Alumina
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  • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
  • C07C2523/48—Silver or gold
  • C07C2523/52—Gold

Definitions

• heterogeneous catalysts comprise at least one metal, which may be in the form of small metal particles deposited on a support, the latter may be a refractory oxide.
• a support may be a refractory oxide.
• the macroscopic distribution of the metal particles in the support constitutes an important criterion of catalytic activity and selectivity.
• the conventional preparation of gold-containing heterogeneous catalysts by dry impregnation of a porous support generally results in a homogeneous distribution of gold within the shaped solid.
• the size of the gold particles obtained is generally high, of the order of 20 to 30 nm, which leads to weakly active catalysts.
• the document US2010 / 010278 discloses a process for the selective hydrogenation of a light cut (C2) on a fixed bed of catalyst, said catalyst comprising a support and a metallic phase comprising either only gold, or palladium and
• the catalyst is prepared by adding a solution of a gold precursor to the support and then the whole is heated to a temperature between 60 and 100 ° C.
• a solution of urea is then added to the solution containing the support and the gold precursor.
• the suspension is kept stirred, generally for a period of between 30 minutes and 24 hours at a temperature between 60 and 100 ° C.
• the catalyst precursor obtained is then recovered and washed.
• the catalyst precursor is then dried and is activated by performing a hydrogen reduction at a temperature between 100 and 500 ° C.
• the catalyst obtained comprises either gold or gold and palladium distributed at the periphery of the support thus forming a crust ("egg-shell" in the English terminology).
• a preparation by precipitation-precipitation with urea as described in this document thus leads to the obtaining of small gold particles distributed in crust on the shaped support.
• the catalyst obtained has improved catalytic properties compared to catalysts known in terms of selective hydrogenation activity, and more particularly selective hydrogenation of light cuts.
• a first subject of the invention relates to a catalyst comprising gold and a porous support containing at least one refractory oxide, in which the gold content is between 0.01 and 5% by weight relative to the total weight of the catalyst, and wherein the gold particles are homogeneously distributed through said porous support and have a size measured by transmission electron microscopy between 0.5 and 5 nm.
• the average size of the gold particles estimated by transmission electron microscopy is between 0.5 nm and 3 nm, and even more preferably less than 3 nm.
• the metal dispersion D of gold is between 30 and 100%.
• said porous support is selected from silica, alumina and silica-alumina.
• Another object according to the invention relates to a process for preparing a catalyst according to the invention, which process comprises the following steps:
• step b) impregnating a porous support containing at least one refractory oxide with said solution obtained in step a);
• step b) subjecting the impregnated porous support obtained in step b) to a maturation in order to obtain a catalyst precursor
• step d) the catalyst precursor obtained in step d) is dried at a temperature between 70 ° C and 300 ° C.
• the maturation step is carried out for a duration of between 0.5 and 40 hours.
• the impregnation stage b) is carried out by dry impregnation.
• the urea / gold molar ratio in step d) is between 1 and 1000.
• the process according to the invention also comprises a step f) in which the dried catalyst obtained at the end of step e) is subjected to a reducing treatment by placing it in contact with a reducing gas.
• the invention relates to a catalyst, in the form of at least one grain, comprising gold and a porous support containing at least one refractory oxide, in which the gold content is between 0.01 and 5%. weight in relation to the total weight of catalyst, preferably between 0.02 and 4% by weight, and even more preferably between 0.02 and 3% by weight, and in which the gold particles are distributed homogeneously through said porous support and has a size measured by transmission electron microscopy (TEM) between 0.5 and 5 nm, preferably less than 4 nm, and even more preferably less than 3.5 nm, and even more preferably less than 3.0 nm, the gold being homogeneously distributed in said porous support grain.
• TEM transmission electron microscopy
• the specific surface area of the porous support is between 1 and 300 m 2 / g, preferably between 2 and 200 m 2 / g, and even more preferably between 3 and 150 m 2 / g.
• the porous support is chosen from magnesium oxide, aluminum oxide (alumina), silicon oxide (silica), zirconium oxide, thorium oxide, or cerium oxide, taken alone or mixed with one another.
• the porous support is an oxide of aluminum (alumina) or of silicon (silica). Even more preferably, said support is alumina.
• the porous carrier grain is in the form of balls, trilobés, extrusions, pellets, or irregular and non-spherical agglomerates whose shape specific may result from a crushing step.
• said support grain is in the form of beads or extrudates.
• said support grain is in the form of beads.
• the size of the catalyst grains is between 1 mm and 10 mm, preferably between 1.5 and 8 mm. If the porous support chosen is alumina, it may be indifferently in the crystallographic forms alpha, delta, tetra, chi, gamma, etc., alone or as a mixture.
• the total pore volume of the support is generally between 0.1 and 1.5 cm 3 / g, preferably between 0.2 and 1.4 cm 3 / g, and even more preferably between 0.25 and 1, 3 cm 3 / g.
• the total pore volume is measured by mercury porosimetry according to the ASTM D4284-92 standard with a wetting angle of 140 °, for example by means of an Autopore ® III model apparatus of the Microméritics ® brand.
• the BET surface area is measured by physisorption with nitrogen.
• the BET surface area is measured by nitrogen physisorption according to ASTM D3663-03 as described in Rouquerol F .; Rouquerol J .; Singh K. "Adsorption by Powders & Porous Solids: Principle, methodology and applications", Academy Press, 1999.
• an element whose concentration is uniform has a coefficient R equal to 1
• a dome-deposited element core concentration greater than the concentration at the edges of the support
• a crust-distributed element concentration at edges larger than the concentration at the heart of the support
• R is determined by the trapezoidal method.
• the invention also relates to a process for preparing the catalyst comprising the following steps: a) an aqueous solution containing a gold precursor is prepared; b) impregnating, preferably by dry impregnation, said solution obtained in step a) on at least one porous carrier grain containing at least one refractory oxide; c) subjecting said impregnated porous carrier grain obtained in step b) to a maturation to obtain a catalyst precursor;
• the preparation method does not include a non-reducing oxidizing or neutral heat treatment stage of the catalyst precursor in order to prevent the formation of large gold particles (ie greater than 5 nm).
• the solution is prepared by dissolving a gold precursor salt in water.
• the salt of the gold precursor used has a degree of oxidation of the metal greater than 0 and is soluble in aqueous solution.
• the salt of the gold precursor may be for example a halide. It may preferably be selected from the group consisting of gold chlorides such as gold trichloride, tetrachloroauric acid, sodium tetrachloraurate or potassium tetrachloraurate. Preferably the precursor used is tetrachloroauric acid.
• the preparation temperature is between 5 ° C and 40 ° C and preferably between 15 ° C and 35 ° C.
• the gold concentration of the solution is preferably between 1 mmol / L and 1 mol / L, ie 0.2 g / l at 200 g / l.
• the solution prepared in step a) is then impregnated onto a porous support.
• the impregnation of the support can be carried out by dry impregnation, in excess or in default, in static or dynamic mode. Dry impregnation is preferred.
• the impregnation can be carried out in one or more successive impregnations.
• the porous support may optionally undergo a set of treatments before the impregnation step, such as calcinations or hydrations.
• said maturation step is carried out in air and preferably in moist air with a relative humidity of between 20 and 100% and preferably between 70 and 100%.
• the precursor of the catalyst may be dried in order to remove all or part of the water introduced during the impregnation, preferably at a temperature of between 50 ° C.
• the volume of the aqueous solution containing at least urea is between 1 and 100 times the pore volume of the shaped catalyst.
• the molar ratio urea / gold is between 1 and 1000, preferably 2 and 700, very preferably 3 and 300.
• the temperature of the solution is kept constant and is between 5 ° C and 120 ° C and preferably between 15 ° C and 100 ° C.
• the residence time of said aqueous solution is between 0.5 and 20 hours.
• the urea is diluted in an organic solvent, for example ethanol, and / or aqueous, preferably the solvent is water.
• the solution containing urea may also contain other organic compounds such as ammonia.
• the solution contains only urea and water.
• the catalyst precursor obtained in step d) can be filtered according to any technique known to those skilled in the art.
• the catalyst precursor is washed, preferably with water.
• the total volume of water engaged for the washing step (s) is between 1 and 30 times the catalytic volume engaged.
• the washing can be carried out in one or more steps. The washing of the catalyst precursor makes it possible to eliminate the presence of urea and / or chlorine in the catalyst precursor.
• the duration of the washing is generally between 1 minute and 10 hours, preferably between 5 minutes and 8 hours, and even more preferably between 10 minutes and 7 hours. e) Drying of the catalyst precursor obtained in step d)
• the catalyst precursor 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 300 ° C., more preferably between 70 ° C. and 250 ° C. vs.
• the drying time is between 0.5 hours and 20 hours.
• 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.
• f) Heat treatment under a reducing atmosphere of the dried catalyst obtained in step e) (optional step)
• 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.
• the reduction temperature is generally between 40 ° C and 500 ° C, preferably between about 100 ° C and about 400 ° 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 0.5 and 10 hours, preferably between 2 and 8 hours.
• the invention also relates to the catalyst obtained from the catalyst preparation process described in the present invention. Use of the catalyst according to the invention
• the catalyst according to the invention can be used in catalytic reactions such as, for example, selective hydrogenations of C2, C3 cuts, C4 cuts, C5 steam cracking and / or catalytic cracking cuts and steam cracking gasolines also known as pyrolysis gasolines.
• the feeds are C2, C3, C4 cuts of steam cracking and / or catalytic cracking.
• the catalyst according to the invention is used in catalytic reactions of selective hydrogenations of light cuts (C2-C4).
• the selective hydrogenation process has progressively been imposed to eliminate polyunsaturated compounds from C3 to C5 petroleum fractions and pyrolysis gasoline because this process allows the conversion of the most unsaturated compounds to the corresponding alkenes while avoiding total saturation and therefore the formation of the corresponding alkanes.
• the selective hydrogenation can be carried out in the gas or liquid phase, preferably in the liquid phase. In fact, a reaction in the liquid phase makes it possible to lower the energy cost and to increase the cycle time of the catalysts.
• the selective hydrogenation is carried out at a temperature between 0 ° C and 500 ° C, a pressure of between 0.1 and 20 MPa, an hourly space velocity between 0.1 and 50 h " 1 for a liquid charge, between 500 and 30,000 h -1 for a gaseous charge.
• the catalyst according to the invention can also be used in CO oxidation reactions, hydrochlorination, gas-to-water conversion (also known as "water-gas shift reaction” in the English terminology), production of ethylene oxide and vinyl chloride.
• the 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, linear butenes, isobutene, pentenes as well as unsaturated molecules containing up to about 15 carbon atoms.
• unsaturated molecules such as ethylene, propylene, linear butenes, 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 C5 + gasoline fraction .
• Examples 1 to 3 relate to processes for the preparation of catalysts not according to the invention and example 4 relates to a process for the preparation of a catalyst.
• Example 5 relates to the application of these catalysts in a selective hydrogenation reaction.
• Example 1 Catalyst C1 - 2% by weight Au / O-AlpQgjnon - according to the invention
• This example shows the conventional preparation of a gold-alumina catalyst by dry impregnation only (and therefore without washing with urea).
• a stock solution of concentration 20 g / L (102 mmol / L) of gold is prepared by dilution with water with stirring at 25 ° C of two grams of HAuCl 4 .3H 2 0 with about 50 mL of Demineralized Water. Part of this solution is then impregnated on 20 grams of a delta alumina with a specific surface area of 140 m 2 / g shaped as beads having a particle size of 2 to 4 mm.
• a step of maturation lasting 20 hours of the impregnated support before drying is carried out under air in a confined and humid environment. The solid obtained is dried under air for 2 hours at 120 ° C. The catalyst is then reduced under a flow of hydrogen for 2 hours at 300 ° C.
• Catalyst C1 contains 2% by weight of gold relative to the total weight of the catalyst and 1.6% by weight of chlorine relative to the total weight of the catalyst.
• the average size of the gold particles measured by transmission electron microscopy is 30 nm.
• the corresponding average dispersion is 4%.
• Example 2 Catalyst C2 - 2% by weight Au / 5-AlpO g (not in accordance with the invention)
• This example shows the preparation of a catalyst by deposition - precipitation in which gold and urea are introduced simultaneously, in solution, as described for example in document FR 2932177.
• a suspension containing 20 grams of alumina delta support of surface area 140 m 2 / g and shaped into beads of 2 to 4 mm in size and 150 ml of water is placed in a reactor and heated to 80 ° C. 20 ml of solution at 20 g / l of gold (102 mmol / l) are introduced into the reactor. Subsequently, 1.2 grams of urea diluted in 20 ml are then added. The molar ratio urea / gold is 100. The suspension is stirred for 6 hours. The solid is filtered on Buchner then washed 3 times with 150 mL of water.
• the solid obtained is dried under air for 2 hours at 120 ° C.
• the catalyst is then reduced under a flow of hydrogen for 2 hours at 300 ° C.
• Catalyst C2 contains 1.7% by weight of gold relative to the total weight of the catalyst and a chlorine content of less than 0.03% by weight relative to the total weight of the catalyst.
• the average size of the gold particles measured by transmission electron microscopy is 4 nm.
• the corresponding average dispersion is 33%.
• Example 3 Catalyst C3 - 2 wt% Au / ⁇ - ⁇ 0 3 (not according to the invention) This example shows the preparation of a catalyst with contacting gold with ammonia (to the place of urea) on a delta-type alumina.
• a stock solution of concentration 20 g / L (102 mmol / L) of gold is prepared by dilution with water with stirring at 25 ° C of two grams of HAuCl 4 .3H 2 0 with about 50 mL of water demineralized. Part of this solution is then impregnated on 20 grams of a delta alumina whose specific surface is 140 m 2 / g shaped in the form of beads in a particle size of 2-4 mm. The solid is then washed 3 times with 150 ml of an ammoniacal solution of concentration 0.2 mol / l. The solid is then washed with 150 mL of water.
• a step of maturation lasting 20 hours of the impregnated support before drying is carried out under air in a confined and humid environment.
• the solid obtained is dried under air for 2 hours at 120 ° C.
• the catalyst is then reduced under a flow of hydrogen for 2 hours at 300 ° C.
• Catalyst C3 contains 1.8% by weight of gold and 0.03% by weight of chlorine relative to the total weight of the catalyst.
• the average size of the gold particles measured by transmission electron microscopy is 5.3 nm.
• the corresponding average dispersion is 23%.
• EXAMPLE 4 Preparation of a C4 Catalyst 2% by Weight Au / ⁇ - ⁇ 0 3
• a stock solution containing 20 g / L (102 mmol / L) of gold is prepared by dilution with water with stirring at 25 ° C two grams of HAuCl 4 .3H 2 0 with about 50 mL of demineralized water. Part of this solution is then impregnated on 20 grams of a delta alumina whose specific surface is 140 m 2 / g shaped into beads in a particle size of 2-4 mm.
• a step of maturation lasting 20 hours of the impregnated support before drying is carried out under air in a confined and humid environment.
• the solid obtained is dried under air for 2 hours at 100 ° C.
• the catalyst is then impregnated with a urea solution of concentration 60 g / l.
• the suspension is stirred at 70 ° C for 4 hours.
• the urea / gold molar ratio is 20.
• the solid is then filtered and washed 4 times with 150 ml of water.
• the solid obtained is dried under air for 2 hours at 120 ° C.
• the catalyst is then reduced under a flow of hydrogen for 2 hours at 300 ° C.
• Catalyst C4 contains 1.9% by weight of gold and a chlorine content of less than 0.03% by weight relative to the total weight of the catalyst.
• the average size of the gold particles measured by transmission electron microscopy is 2.5 nm.
• the corresponding average dispersion is 44%.
• Catalysts C1 to C4 are tested for the selective hydrogenation of butadiene.
• a feedstock comprising 0.3% butadiene, 30% butene, 20% hydrogen and the balance helium is treated with catalysts C1, 02, 03, and 04.
• the catalysts 01 to 04 are activated under a flow of pure hydrogen at 300 ° C. for 2 hours. 100 mg of catalysts are placed in a tubular reactor in down flow mode. The reactor pressure is maintained at 0.1 MPa. A volume hourly velocity (GHSV) of 30,000 h -1 is applied The composition of the feedstock and the effluent are continuously measured at the outlet of the reactor by gas chromatography.
• GHSV volume hourly velocity
• the catalyst C4 is more active than the catalysts C1, C2 and C3.

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• 2015
  • 2015-03-05 FR FR1551873A patent/FR3033268B1/fr not_active Expired - Fee Related
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