EP1519789A1 - Method for preparing catalysts for heterogeneous catalysis by multiple-phase impregnation, catalysts and use of said catalysts - Google Patents

Method for preparing catalysts for heterogeneous catalysis by multiple-phase impregnation, catalysts and use of said catalysts

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Publication number
EP1519789A1
EP1519789A1 EP03753632A EP03753632A EP1519789A1 EP 1519789 A1 EP1519789 A1 EP 1519789A1 EP 03753632 A EP03753632 A EP 03753632A EP 03753632 A EP03753632 A EP 03753632A EP 1519789 A1 EP1519789 A1 EP 1519789A1
Authority
EP
European Patent Office
Prior art keywords
support
use according
impregnation
agent
active phase
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP03753632A
Other languages
German (de)
French (fr)
Inventor
Cuong Pham-Huu
Nicolas Keller
Marc J. Ledoux
Jean-Mario Nhut
Laurie Pesant
Claude Estournes
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centre National de la Recherche Scientifique CNRS
Universite Louis Pasteur Strasbourg I
SICAT Societe Industrielle de Creations et d'Applications Textiles SARL
Original Assignee
Centre National de la Recherche Scientifique CNRS
Universite Louis Pasteur Strasbourg I
SICAT Societe Industrielle de Creations et d'Applications Textiles SARL
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Application filed by Centre National de la Recherche Scientifique CNRS, Universite Louis Pasteur Strasbourg I, SICAT Societe Industrielle de Creations et d'Applications Textiles SARL filed Critical Centre National de la Recherche Scientifique CNRS
Publication of EP1519789A1 publication Critical patent/EP1519789A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/864—Removing carbon monoxide or hydrocarbons
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/42—Platinum
    • 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
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/20—Carbon compounds
    • B01J27/22—Carbides
    • B01J27/224—Silicon carbide
    • 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
    • B01J37/0203—Impregnation the impregnation liquid containing organic compounds
    • 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
    • B01J37/0205—Impregnation in several steps
    • 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

Definitions

  • the invention relates to the field of catalysts based on ⁇ -SiC, for heterogeneous catalysis, and in particular the biphasic impregnation of supports with high specific surface 0 with active phase precursors to form such a catalyst.
  • the catalysts currently used in the fields of the chemical or petrochemical industry, or in the depollution of exhaust gases from motor vehicles are essentially in the form of grains, extrudates, barrels or monoliths to name only the most used forms. These materials play the role of active phase support or precursor of said active phase, an active phase being in the latter case deposited on said support to form the catalyst. This active phase often consists of metals or metal oxides.
  • the deposition of the active phase on the supports currently used is carried out by means of an impregnation step, during which the solution containing a precursor of the active phase is deposited homogeneously over the entire surface of the support. Most often, this precursor is then subjected to an activation treatment.
  • the precursor in question can be a salt or an organometallic compound.
  • the precursor solution can be an aqueous solution or an organic solution.
  • aqueous solution or an organic solution.
  • Patent application WO 99/20390 (National Center for Scientific Research) describes the impregnation of a non-porous Si 3 N powder with a BET specific surface area of 8.8 m 2 / g with a solution of bis-acetyl- palladium (II) acetonate in toluene, as well as the manufacture, characterization and use of the catalyst thus obtained.
  • the problem that the present invention seeks to solve is to present a new ⁇ -SiC catalyst comprising a support and at least one active phase with controlled localization, in which the influence of the phenomena of diffusion of the reagents towards the active sites and of retro diffusion of the products towards the surface of the catalyst over the kinetics of the reaction operated using said catalyst is lower than in the case of known catalysts.
  • the first object of the present invention is a process for impregnating a ⁇ -SiC support having a specific surface, determined by the BET method of nitrogen adsorption at the temperature of liquid nitrogen according to standard NF X 11-621, at least equal to 1 m 2 / g and comprising comprising macropores with a size between 0.05 and 10 ⁇ m, and optionally in addition to the mesopores with a size between 4 and 40 nm, said process comprising at least the following steps:
  • the active phase precursor preferably a metallic compound
  • Said precursor can be advantageously chosen from salts and compounds organo-metallic of said elements.
  • Yet another object of the present invention is the catalyst capable of being obtained by said process for the preparation of a catalyst.
  • Yet another object of the present invention is the use of the catalyst obtained by said process for catalyzing chemical reactions, such as the oxidation of methane or other hydrocarbons, or the oxidation of carbon monoxide.
  • FIG. 1 schematically shows two profiles of the macroscopic localization of the active phase relative to the support in catalysts according to the state of the art, (a): crust deposition, (b): deposition in the center, (c ): uniform deposit.
  • Figure 2 shows schematically the location of the active phase in a catalyst.
  • Catalyst according to the invention comprising a support with hydrophilic / hydrophobic properties, impregnated by the two-phase impregnation method.
  • the active phase is found on the hydrophobic zones (outside the pores).
  • FIG. 3 shows the conversion of CH 4 to CO 2 as a function of the reaction temperature for an hourly space velocity of 15,000 h ⁇ 1 on the Pd (0) / ⁇ -SiC catalysts prepared by conventional impregnation (black dots) and biphasic (open circles).
  • Figure 4 shows an enlargement of Figure 3 highlighting the half-conversion temperatures.
  • FIG. 5 shows the conversion of CH into CO 2 as a function of the reaction temperature for an hourly space velocity of 40,000 h -1 on the Pd (0) / ⁇ -SiC catalysts prepared by conventional impregnation (black dots) and biphasic (open circles).
  • FIG. 6 shows an enlargement of Figure 5 highlighting the half-conversion temperatures.
  • FIG. 7 shows the conversion of CH4 to CO 2 as a function of the reaction temperature for an hourly space velocity of 200,000 h ⁇ 1 on the Pd (0) / ⁇ -SiC catalysts prepared by conventional impregnation (black dots) and biphasic (open circles).
  • Figure 8 shows an enlargement of Figure 7 highlighting the half-conversion temperatures.
  • Figure 9 shows the size distribution of macropores in two ⁇ -SiC supports which are suitable for carrying out the invention.
  • the problem posed is solved by means of an impregnation method called "two-phase impregnation".
  • This impregnation method the principle of which is described in the documents US Pat. of the agent, either the hydrophilic zones or the hydrophobic zones of the support in order to be able to selectively deposit and thus locate the precursor compound forming the active phase, either on the hydrophobic zones, or on the hydrophilic zones depending on the intended reaction.
  • the method thus makes it possible to control the localization of the active phase in a microscopic manner relative to the matrix of the support and not conventionally in a macroscopic manner as described above.
  • polar agent is understood here to mean a molecule having a permanent dipole moment. Agent X is less polar than Agent Y, if the permanent dipole moment of Agent X is greater than that of Agent Y.
  • water is a polar agent, and toluene is a less polar agent than water.
  • the present invention applies to catalysts manufactured on a ⁇ -SiC support having two distinct surface functions: hydrophobic and hydrophilic.
  • Any ⁇ -SiC catalyst support having these two functions may be suitable, provided that they have sufficient porosity and a specific surface, determined by the BET method of nitrogen adsorption, that is to say at least 1 m 2 / g, and preferably at minus 2 m 2 / g.
  • the support has a specific surface of between 1 and 100 m 2 / g.
  • the supports are preferred having a specific surface greater than 10 m 2 / g, and preferably greater than 20 m 2 / g. This specific surface is due to the presence of pores.
  • micropores with an average size typically less than 4 nm there are three types of pores: micropores with an average size typically less than 4 nm, mesopores with a size typically between 4 and 50 nm, and macropores, which can form networks, and whose diameter is typically greater than 50 nm.
  • supports are preferred whose total porosity, measured by nitrogen adsorption, essentially consists of mesopores between 4 and 40 nm and a macroporous system with an average diameter between 0, 05 and 100 ⁇ m, preferably between 0.05 and 10 ⁇ m, and even more preferably between 0.05 and 1 ⁇ m.
  • the pore size distribution is demonstrated by penetration of mercury.
  • the pores can also be directly observed by scanning electron microscopy.
  • the size distribution of the macropores is between 0.06 and 0.4 ⁇ m, and even more preferably between 0.06 and 0.2 ⁇ m.
  • a ⁇ -SiC silicon carbide is used in the form of extrudates or beads which is prepared using any of the synthesis techniques described in patent applications EP 0 313 480 A, EP 0440 569 A, EP 0 511 919 A, EP 0 543 751 A and EP 0 543 752 A.
  • the surface of the silicon carbide ( ⁇ -SiC) prepared according to one of the references indicated above consists of two types of zones of different reactive nature.
  • a first sort of zone hydrophobic in nature, constitutes the external surface of the solid and lines the internal surface of the macropores. These zones are essentially constituted by planes of low Miller indices, stable and having a very low reactivity with respect to the oxygen of the air. In the presence of organic solvents, wetting is carried out essentially on these hydrophobic zones.
  • the second kind of zone is hydrophilic in nature and essentially concerns the internal walls of the solid mesopores. These zones consist of atomic planes with high Miller indices, and therefore rich in structural defects.
  • the use of the bi-impregnation technique therefore makes it possible to neutralize these mesopores for the deposition of an active phase in the macropores, or else to deposit first an active phase in the mesopores and then another active phase in the macropores.
  • the first objective can be achieved in a particular embodiment by a preliminary heat treatment of the support under inert gas, which has the effect of reducing the mesoporosity.
  • the support as described above is impregnated as described below, playing on its hydrophobic and hydrophilic properties, in order to be able to modify and control the location of the active phase with respect to the pore network, in order to improve the access of the reagents to the active sites and in order to keep the same reaction yield while reducing the residence time of the reagents and the porosity of the support.
  • the biphasic impregnation mode consists of two successive impregnation steps, the first using a polar agent A (such as water), the second using a less polar agent B than agent A, and in particular of an apolar organic liquid.
  • the agents can advantageously be liquids.
  • Said liquids can be solutions, and can in particular contain metal salts.
  • the first impregnation step consists of wetting the ⁇ -SiC support with water (preferably demineralized or distilled water).
  • water preferably demineralized or distilled water.
  • the volume of water is equal to or slightly greater than the total pore volume of the solid. This operation makes it possible to completely saturate the hydrophilic zones of the surface of the solid which are essentially located inside the pores of the material. The water thus remains trapped inside the pores leaving free the hydrophobic zones which constitute the external surface of the solid.
  • a polar liquid containing one or more soluble compounds is used during this first impregnation step.
  • Said soluble compound can be a metallic compound.
  • Said metal compound can play the role of active phase or active phase precursor.
  • the impregnated solid is dried superficially, in order to remove the moisture from the external surface of the body, while keeping the liquid in the pores.
  • a temperature of 50 ° C at normal pressure is suitable for an aqueous liquid; the precise conditions (temperature and duration) for a given support can be easily determined using simple routine experiments.
  • a precursor of the active phase is deposited on the solid, preferably in an essentially apolar organic solution.
  • precursor of the active phase is understood to mean a compound of a metal, typically a salt of a metal or an organometallic compound, which forms, after a calcination treatment optionally followed by other treatments such as reduction , the active phase of the catalyst. It is desirable to select the solvent so that the affinity of the organic solvent with the hydrophobic zones allows perfect wetting of the latter, while the interior of the pores remains inaccessible due to the presence of the water previously impregnated. .
  • the impregnated support is then dried, for example in air at room temperature and then at a temperature advantageously between 100 ° C. and 200 ° C. in an oven in order to vaporize the organic solvent.
  • the dried solid is calcined in air at a temperature typically between 200 ° C and 500 ° C and more preferably between 300 ° C and 400 ° C for a period which depends on the charge of the furnace, the characteristics of the solvent and those of the support, in order to decompose the precursor of the active phase into its corresponding metal oxide.
  • the calcined solid can be used as it is as a catalyst.
  • a second, optional, activation step which is advantageously a treatment under reactive gas, and preferably a reduction.
  • the oxide can either be reduced under a flow of hydrogen H 2 to obtain the corresponding metal, or treated with other gases in order to obtain the desired active phase.
  • the active phase thus obtained is located essentially on the surfaces made up of the hydrophobic zones of the support, ie the surfaces outside the pores.
  • the localization of the active phase can be diagrammatically compared the porosity of the support as shown in Figure 2.
  • the active phase can consist of any metal having a salt soluble in a weakly polar solvent, or alternatively an organometallic compound which is sufficiently stable.
  • these metals there may be mentioned in particular: Co, Ni, Fe, Cu, Pt, Pd, Rh, Ru, Ir.
  • the concentration of said active phase can be included in a relatively wide range of around ten ppm (parts per million , relative to the mass) up to several tens of percent (relative to the mass), depending on the intended reaction.
  • it is between 0.1 and 5% relative to the mass of the catalyst.
  • Another variant taking advantage of the advantage offered by this impregnation method concerns the deposition of two different compounds on the same support, using for each of them a solvent of adequate polarity and thus allowing precise control of their respective localization.
  • the two-phase impregnation method described can also be applied to successively deposit two compounds each forming a active phase, used separately because of their different and particular catalytic properties, but located on the same support.
  • the catalyst thus prepared can be used under different conditions and in various reaction media. More particularly, it can be used for reactions having a very rapid rate of passage of reagents, ie for the depollution of exhaust gases from motor vehicles, or for reactions where the overall selectivity could be affected by secondary reactions between the products and one of the excess reagents, during the diffusion of the products from the active sites to the external surface of the support.
  • the improved accessibility of active sites for reactants in the gas phase or in the liquid phase allows a significant increase in the overall yield of the reaction. Indeed, when the active phase is deposited directly on the external surface of the support or in a macroporosity, the accessibility of the active sites for the reactants in gas or liquid phase can be considerably increased; this increases the yield of the reaction.
  • the extremely short residence time between the active phase and the reactants as well as the reaction products makes it possible to appreciably reduce the formation of the secondary products.
  • the duration of migration of the products through the porosity of the support to reach the gas or liquid phase, or more generally escaping from the catalyst grain can be a very important factor in the overall selectivity of the reaction.
  • the fact of locating the active phase on a hydrophobic zone has a certain advantage when one of the products of the reaction is water.
  • Water can induce undesirable modifications to the active phase due to its oxidizing character.
  • the water formed can adsorb on the active sites of the catalyst and oxidize the latter, while water adsorption is avoided when the active phase is located on the hydrophobic areas.
  • This advantage is also significant when the reaction is carried out in the presence of water or any other solvent which interacts strongly with the hydrophilic zones and which has oxidizing properties in the reaction medium.
  • the deposition method according to the invention also makes it possible to considerably reduce the content of the active phase necessary compared to that used in the crust impregnations. Therefore, the loss of the active phase, which can take place either by sintering or by attrition during the impregnation or more generally during the phase or phases of preparation or activation of the catalyst as well as during the catalytic test, is considerably reduced; this increases the service life of the catalyst.
  • the catalysts prepared in the context of the present invention combine the advantages acquired on conventional macroscopic supports with those of better accessibility of the reagents to the active sites and better evacuation of the products. They thus allow a non-negligible gain in the yields of the various reactions while maintaining a maximum dispersion of the active phase so as not to harm the overall yield of the reaction.
  • the preferred embodiment using extruded supports, beads or pellets of ⁇ -SiC also makes it possible to benefit from the specific advantages associated with this type of support.
  • the catalyst according to the invention can be used in various fields, such as the chemical or petrochemical industry. For example, it can catalyze the oxidation of methane or the oxidation of carbon monoxide. It can also be used in the depollution reactions of exhaust gases from internal combustion engines (in particular those operating with liquid fuels such as petrol or diesel) where it makes it possible to obtain a better efficiency, thanks to. a very short contact time, and very good accessibility of the active sites of the catalyst by the reagents.
  • a series of examples illustrating the invention is given below, without implied limitation.
  • This example illustrates in a detailed manner the impregnation of an active phase based on platinum by the two-phase impregnation method on a support based on extruded silicon carbide ( ⁇ -SiC).
  • the support based on extruded silicon carbide ⁇ -SiC is previously impregnated with a solution of distilled water whose volume is equal to the pore volume of the support, in order to block the entry of the pores of the solid. . 5 g of silicon carbide (BET specific surface 25 m 2 / g) are therefore first pre-impregnated with 3 mL of distilled water and then dried for 5 minutes at 50 ° C.
  • the material is in a second step impregnated according to the drop method with a solution of platinum bis-acetylacetonate in toluene (non-polar solvent) at a rate of 2% by weight of platinum relative to the silicon carbide support (i.e.
  • the solid obtained is dried in air at room temperature and then at 150 ° C in an oven for 2 hours. It is then calcined in air at 350 ° C for 2 hours to transform the platinum salt into its corresponding oxide, then reduced to 400 ° C under a stream of hydrogen for 2 hours to form the metallic platinum.
  • the metallic platinum Pt is then located outside the pores of the silicon carbide.
  • This example illustrates in the case of the total oxidation of methane to carbon dioxide the influence of the impregnation mode, namely purely aqueous to locate the active phase in the pores of the support, and two-phase to locate said active phase outside the mesoporosity of the support.
  • Two catalysts based on palladium metal supported on grains of silicon carbide ( ⁇ -SiC, grains of diameter between 0.4 mm and 1 mm, specific surface 25 m 2 / g) are prepared with a palladium metal content of 1% in mass of the silicon carbide support: for one of the two catalysts, the purely aqueous impregnation method is used according to the state of the art, while for the other, the two-phase impregnation method is used according to the invention.
  • the purely aqueous impregnation is carried out by impregnating the grains of silicon carbide ( ⁇ -SiC) with an aqueous solution of Pd ⁇ (NO 3 ) .H 2 O. After drying in air at room temperature, the solid is placed at 1 oven at 100 ° C for 2 hours. The dried solid is then calcined in air at 350 ° C. for 2 hours in order to form the palladium oxide PdO.
  • the palladium metal catalyst supported on silicon carbide is obtained by reduction of its oxide counterpart at 400 ° C. under hydrogen for 2 hours. This purely aqueous impregnation leads to obtaining the palladium phase Pd (0) localized in the porosity of the support based on silicon carbide.
  • the two-phase impregnation of the silicon carbide support is carried out by first impregnating the support with an aqueous solution of a volume equal to the pore volume of said support. After drying at 50 ° C for 5 minutes, 1% by mass of palladium is then deposited on the support in the form of palladium acetylacetonate (C 10 H 4 ⁇ Pd) in toluene. The material is then subjected to the same treatments as the catalyst prepared by traditional aqueous impregnation. The palladium oxide is then reduced to metallic palladium by heat treatment under hydrogen at 400 ° C. for 2 hours. The metallic palladium particles are then located outside the pores of the silicon carbide.
  • the hourly space velocity (in English "gas hourly space velocity") is defined as being the ratio between the total flux and the volume of catalyst.
  • Table 2 shows the half-conversion temperatures obtained on the two catalysts. function of the hourly space volume velocity of the flow containing methane and oxygen at a rate of 1% and 4% by volume respectively.
  • the half-conversion temperature on the catalyst prepared by the two-phase impregnation method is 300 ° C. compared to 316 ° C. on the catalyst prepared by the method d "classic impregnation. This difference increases when the hourly space velocity increases, and the temperature difference is 23 ° C. for a space velocity of 40,000 h " .
  • This gap of temperature reaches 57 ° C. when the total oxidation of methane is carried out at very high hourly space volume velocity, namely 200,000 h "1 .
  • Table 2 Half-conversion temperatures obtained according to the method of impregnation of the catalyst as a function of the hourly space volume velocity of the reaction.
  • the catalyst prepared by two-phase impregnation according to the invention has better performance, that is to say a significantly lower half-conversion temperature than the catalyst prepared by single-phase aqueous impregnation according to the state of the technical.
  • This improved performance of the catalyst according to the invention prepared by two-phase impregnation can be attributed to the presence of palladium on the external surface of the support; palladium, which forms the active phase of the catalyst, thus has better accessibility vis-à-vis the reagent to be transformed.
  • This example shows the distribution of the macropores in two supports of ⁇ -SiC which are very suitable for carrying out the invention, see FIG. 9. They are extraded into ⁇ -SiC.
  • Support Z1 was made from Si -f C + resin, support Z2 with the addition of ethanol. It can be seen that the support Z1 has a distribution centered around around 0.06 ⁇ m, while the support Z2 has a distribution centered around around 0.11 ⁇ m.

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Abstract

The invention concerns a method for so-called two-phase impregnation of a beta -SiC support with high specific surface area, said method comprising at least the following steps: (a) a first impregnating step which consists in impregnating at least once said support with a polar agent A, (b) a second impregnating step which consists in impregnating at least once said support with at least an agent B less polar than agent A. Said method enables the production of novel catalysts for heterogeneous catalysis.

Description

METHODE DE PREPARATION DE CATALYSEURS POUR CATALYSE HETEROGENE PAR IMPREGNATION EN PLUSIEURS ETAPES, CATALYSEURS ET UTILISATION DESDITS CATALYSEURSPROCESS FOR THE PREPARATION OF CATALYSTS FOR HETEROGENEOUS CATALYSIS BY IMPREGNATION IN SEVERAL STEPS, CATALYSTS AND USE OF SAID CATALYSTS
55
Domaine de l'inventionField of the invention
L'invention concerne le domaine des catalyseurs à base de β-SiC, pour catalyse hétérogène, et notamment l'imprégnation biphasique de supports à haute surface 0 spécifique avec des précurseurs de phases actives pour former un tel catalyseur.The invention relates to the field of catalysts based on β-SiC, for heterogeneous catalysis, and in particular the biphasic impregnation of supports with high specific surface 0 with active phase precursors to form such a catalyst.
Etat de la techniqueState of the art
Les catalyseurs actuellement utilisés dans les domaines de l'industrie chimique ou pétrochimique, ou dans la dépollution des gaz d'échappement des véhicules à moteur se présentent essentiellement sous forme de grains, d'extradés, de barillets ou de monolithes pour ne citer que les formes les plus utilisées. Ces matériaux jouent le rôle de support de phase active ou de précurseur de ladite phase active, une phase active étant dans ce dernier cas déposée sur ledit support pour former le catalyseur. Cette phase active est souvent constituée de métaux ou d'oxydes métalliques.The catalysts currently used in the fields of the chemical or petrochemical industry, or in the depollution of exhaust gases from motor vehicles are essentially in the form of grains, extrudates, barrels or monoliths to name only the most used forms. These materials play the role of active phase support or precursor of said active phase, an active phase being in the latter case deposited on said support to form the catalyst. This active phase often consists of metals or metal oxides.
Le dépôt de la phase active sur les supports actuellement utilisés est réalisé au moyen d'une étape d'imprégnation, au cours de laquelle la solution contenant un précurseur de la phase active est déposée de manière homogène sur toute la surface du support. Le plus souvent, ce précurseur est ensuite soumis à un traitement d'activation. Le précurseur en question peut être un sel ou un composé organo-métallique.The deposition of the active phase on the supports currently used is carried out by means of an impregnation step, during which the solution containing a precursor of the active phase is deposited homogeneously over the entire surface of the support. Most often, this precursor is then subjected to an activation treatment. The precursor in question can be a salt or an organometallic compound.
La méthode classique d'imprégnation (décrite par exemple dans l'article « Catalyse hétérogène » par D. Cornet, paru, dans le traité « Génie et procédé chimiques » de la collection « Techniques de l'Ingénieur », Volume Jl, article J 1250, p. 23/24 (septembre 1992)) ne permet pas de contrôle de la localisation précise de la phase active dans le catalyseur.The classic method of impregnation (described for example in the article “Heterogeneous catalysis” by D. Cornet, published in the treaty “Chemical engineering and process” from the collection “Techniques de l'Ingénieur”, Volume Jl, article J 1250, p. 23/24 (September 1992)) does not allow control of the precise localization of the active phase in the catalyst.
Selon l'état de la technique, la solution de précurseur peut être une solution aqueuse ou une solution organique. A titre d'exemple, il est connu d'imprégner des supports de SiO2, Al2O3, α-SiC (polytype 6H) ou β-SiC (cubique) avec une solution du bis-acétyl- acétonate de palladium (II), Pd(CsH7O2)2 dans du toluène (voir l'article de C. Méthivier et al., « Pd/SiC Catalysts — Characterization and Catalytic Activity for the Méthane Total Oxidation », Journal of Catalysis 173, p. 374-382 (1998)). La demande de brevet WO 99/20390 (Centre National de la Recherche Scientifique) décrit l'imprégnation d'une poudre de Si3N non poreuse de surface spécifique BET de 8,8 m2/g par une solution de bis-acétyl-acétonate de palladium (II) dans du toluène, ainsi que la fabrication, la caractérisation et l'utilisation du catalyseur ainsi obtenu.According to the state of the art, the precursor solution can be an aqueous solution or an organic solution. By way of example, it is known to impregnate supports of SiO 2 , Al 2 O 3 , α-SiC (polytype 6H) or β-SiC (cubic) with a solution of palladium bis-acetyl acetonate (II ), Pd (CsH 7 O 2 ) 2 in toluene (see the article by C. Méthivier et al., “Pd / SiC Catalysts - Characterization and Catalytic Activity for the Methane Total Oxidation”, Journal of Catalysis 173, p. 374-382 (1998)). Patent application WO 99/20390 (National Center for Scientific Research) describes the impregnation of a non-porous Si 3 N powder with a BET specific surface area of 8.8 m 2 / g with a solution of bis-acetyl- palladium (II) acetonate in toluene, as well as the manufacture, characterization and use of the catalyst thus obtained.
On a aussi utilisé des composés organiques du métal à l'état pur ou dilué, lorsque ces composés se présentaient à l'état liquide. Tel est le cas du composé (C3H7Sn)2O (voir : D. Roth et al., « Combustion of méthane at low température over Pd and Pt catalysts supported on Al2O3, SnO2 and Al2O3-grafted SnO2 », paru dans la revue Topics in Catalysis, vol. 16/17, n° 1-4, p. 77 - 82 (2001)). Ce même composé a été utilisé aussi avec des supports de Sι3N sous forme de poudre avec une surface BET de 9 m /g (voir l'article de C. Méthivier et al., « Pd/Si3N catalysts : préparation, characterization and catalytic activity for the méthane oxidation », Applied Catalysis A : gênerai, vol 182, p. 337-344 (1999)).Organic compounds of the metal have also been used in the pure or diluted state, when these compounds are present in the liquid state. This is the case of the compound (C 3 H 7 Sn) 2 O (see: D. Roth et al., “Combustion of methane at low temperature over Pd and Pt catalysts supported on Al 2 O 3 , SnO 2 and Al 2 O 3 -grafted SnO 2 ”, published in the journal Topics in Catalysis, vol. 16/17, n ° 1-4, p. 77 - 82 (2001)). This same compound was also used with Sι 3 N supports in powder form with a BET surface of 9 m / g (see the article by C. Méthivier et al., “Pd / Si 3 N catalysts: preparation, characterization and catalytic activity for the methane oxidation ”, Applied Catalysis A: gênerai, vol 182, p. 337-344 (1999)).
L'article « Exhaust gas catalysts for heavy-duty applications : influence of the Pd particle size and particle size distribution on the combustion of natural gas and biogas » de E. Pocoroba et al., paru dans la revue Topics in Catalysis, vol 16/17, n° 1-4, p. 407- 412 (2001) décrit l'imprégnation de monolithes de cordiérite (γ-Al2O3) avec une solution aqueuse de Pd(NO3)2 ou avec une microémulsion, c'est-à-dire une solution colloïdale contenant des particules de palladium de taille nanometrique, obtenue par réduction, à l'aide une solution aqueuse d'hydrazine, d'une émulsion formée à partir d'une solution aqueuse de Pd(NO3)2 et un surfactant non ionique.The article "Exhaust gas catalysts for heavy-duty applications: influence of the Pd particle size and particle size distribution on the combustion of natural gas and biogas" by E. Pocoroba et al., Published in the journal Topics in Catalysis, vol 16 / 17, n ° 1-4, p. 407-412 (2001) describes the impregnation of cordierite monoliths (γ-Al 2 O 3 ) with an aqueous solution of Pd (NO 3 ) 2 or with a microemulsion, that is to say a colloidal solution containing nanometric-sized palladium particles, obtained by reduction, using an aqueous hydrazine solution, of an emulsion formed from an aqueous solution of Pd (NO 3 ) 2 and a nonionic surfactant.
Aucune de ces techniques ne permet le contrôle de la localisation de la phase active par rapport au support, et notamment par rapport aux caractéristiques de porosité du support. De plus, dans le cas où l'on dépose deux ou plusieurs métaux pour former une ou plusieurs phases actives au sein du même catalyseur, les techniques connues ne permettent pas non plus de contrôler la localisation des différentes phases actives les unes par rapport aux autres.None of these techniques makes it possible to control the location of the active phase with respect to the support, and in particular with respect to the porosity characteristics of the support. In addition, in the case where two or more metals are deposited to form one or more active phases within the same catalyst, the known techniques also do not make it possible to control the location of the different active phases with respect to each other. .
Les techniques connues permettant un contrôle de la localisation de la phase active par rapport au support sont à l'heure actuelle peu utilisées. Les méthodes existantes sont de performance assez limitée, puisqu'elles permettent soit de déposer la phase active exclusivement sur la surface externe du support (appelée imprégnation en croûte ou egg-shell, la surface du support étant recouverte par une couche épaisse de phase active), soit de confiner la phase active à l'intérieur de la matrice du support (voir figure 1). Ces méthodes sont décrites dans le livre « Fundamentals of Industriel Catalytic Processes » par F.J. Farrauto et CH. Bartholomew (paru chez l'éditeur Chapman & Hall), notamment sur les pages 89 à 93. On connaît par ailleurs la méthode d'imprégnation bi-phasique.Known techniques allowing a control of the localization of the active phase with respect to the support are currently little used. The existing methods are of relatively limited performance, since they allow either to deposit the active phase exclusively on the external surface of the support (called impregnation in crust or egg-shell, the surface of the support being covered by a thick layer of active phase) , or to confine the active phase inside the matrix of the support (see figure 1). These methods are described in the book “Fundamentals of Industriel Catalytic Processes” by F.J. Farrauto and CH. Bartholomew (published by the editor Chapman & Hall), in particular on pages 89 to 93. We also know the two-phase impregnation method.
Dans le premier cas (imprégnation en croûte, voir figure l(a)), une concentration importante de phase active est nécessaire afin d'assurer un bon recouvrement de la surface externe du support. Il en résulte une fragilisation du matériau conduisant à une baisse importante de la tenue mécanique de la phase active, en raison des problèmes de frittage et d'attrition. Cela aboutit à une perte progressive de phase active en fonction du temps. De plus, dans ces préparations, le contrôle de la localisation de la phase active est seulement possible par rapport à la matrice macroscopique et non par rapport à la porosité dudit support. Dans le deuxième cas (imprégnation interne, voir figure l(b)), la localisation particulière de la phase active à-Pintérieur de la matrice du support permet d! éviter es.. problèmes d'attrition causés par les frottements des supports les uns par rapport aux autres lors des phases de fonctionnement dudit matériau. Cependant, cette localisation impose que les réactifs et les produits de réaction, en phase gaz ou liquide, diffusent à travers la matrice poreuse du support avant d'atteindre la phase active ou de sortir du grain de catalyseur. Il en résulte une efficacité moindre, et ceci surtout dans deux situations : surtout lorsque la vitesse de passage des réactifs est élevée, ainsi que lorsque la réaction globale est sujette à des réactions parallèles ou successives, conduisant à la formation de produits non désirés.In the first case (crust impregnation, see Figure 1 (a)), a significant concentration of active phase is necessary in order to ensure good recovery of the external surface of the support. This results in embrittlement of the material leading to a significant drop in the mechanical strength of the active phase, due to the problems of sintering and attrition. This results in a gradual loss of active phase over time. In addition, in these preparations, the control of the localization of the active phase is only possible with respect to the macroscopic matrix and not with respect to the porosity of said support. In the second case (internal impregnation, see FIG. 1 (b)), the particular localization of the active phase inside the matrix of the support makes it possible! avoid es .. attrition problems caused by the friction of the supports with respect to each other during the operating phases of said material. However, this location requires that the reactants and reaction products, in the gas or liquid phase, diffuse through the porous matrix of the support before reaching the active phase or leaving the catalyst grain. This results in lower efficiency, and this especially in two situations: especially when the speed of passage of the reactants is high, as well as when the overall reaction is subject to parallel or successive reactions, leading to the formation of unwanted products.
On sait que lors des réactions entre une phase gazeuse contenant les réactifs à transformer et un catalyseur solide, la localisation de la phase active par rapport à la porosité du catalyseur est un facteur très important qui agit à la fois sur le taux de conversion et sur la sélectivité de la réaction. En effet, lorsque la phase active est localisée à l'intérieur de la porosité du support, la conversion et la sélectivité de la réaction peuvent être influencées essentiellement par deux facteurs:It is known that during the reactions between a gas phase containing the reactants to be transformed and a solid catalyst, the location of the active phase with respect to the porosity of the catalyst is a very important factor which acts both on the conversion rate and on selectivity of the reaction. In fact, when the active phase is located within the porosity of the support, the conversion and the selectivity of the reaction can be influenced essentially by two factors:
(i) la diffusion des réactifs de la phase gaz vers les sites actifs : Plus la localisation de la phase active est profonde dans le réseau des pores, plus la diffusion des réactifs de la phase active vers les sites actifs limite la vitesse de la réaction et entraîne une baisse de la conversion par rapport à celle attendue en absence des phénomènes de diffusion. Ce phénomène est accentué lorsque la vitesse de passage des réactifs est élevée.(i) the diffusion of reactants from the gas phase to the active sites: The deeper the localization of the active phase in the pore network, the more the diffusion of the reactants from the active phase to the active sites limits the speed of the reaction and causes a decrease in the conversion compared to that expected in the absence of diffusion phenomena. This phenomenon is accentuated when the speed of passage of the reactants is high.
(ii) la rétro-diffusion des produits des sites actifs vers l'extérieur du support est aussi très sensible à la localisation desdits sites actifs. En effet, plus la porosité est tortueuse, plus les réactions secondaires vont avoir lieu lors de la rétro-diffusion des produits vers la surface externe et entraînant ainsi une baisse sensible de la sélectivité globale de la réaction.(ii) the back-distribution of products from active sites to the outside of the medium is also very sensitive to the location of said active sites. In fact, the more tortuous the porosity, the more the side reactions will take place during the backscattering of the products to the external surface and thus resulting in a significant decrease in the overall selectivity of the reaction.
Le problème que la présente invention cherche à résoudre est de présenter un nouveau catalyseur en β-SiC comprenant un support et au moins une phase active à localisation contrôlée, dans lequel l'influence des phénomènes de diffusion des réactifs vers les sites actifs et de rétro-diffusion des produits vers la surface du catalyseur sur la cinétique de la réaction exploitée à l'aide dudit catalyseur est moins élevée que dans le cas des catalyseurs connus.The problem that the present invention seeks to solve is to present a new β-SiC catalyst comprising a support and at least one active phase with controlled localization, in which the influence of the phenomena of diffusion of the reagents towards the active sites and of retro diffusion of the products towards the surface of the catalyst over the kinetics of the reaction operated using said catalyst is lower than in the case of known catalysts.
Objet de l'inventionSubject of the invention
Le premier objet de la présente invention est un procédé d'imprégnation d'un support en β-SiC ayant une surface spécifique, déterminée par la méthode BET d'adsorption d'azote à la température de l'azote liquide selon la norme NF X 11-621, au moins égale à 1 m2/g et comportant comportant des macropores d'une taille comprise entre 0,05 et 10 μm, et optionnellement en plus des mesopores d'une taille comprise entre 4 et 40 nm, ledit procédé comportant au moins les étapes suivantes :The first object of the present invention is a process for impregnating a β-SiC support having a specific surface, determined by the BET method of nitrogen adsorption at the temperature of liquid nitrogen according to standard NF X 11-621, at least equal to 1 m 2 / g and comprising comprising macropores with a size between 0.05 and 10 μm, and optionally in addition to the mesopores with a size between 4 and 40 nm, said process comprising at least the following steps:
(a) une première étape d'imprégnation au cours de laquelle on imprègne au moins une fois ledit support par un agent polaire A,(a) a first impregnation step during which said support is impregnated at least once with a polar agent A,
(b) une deuxième étape d'imprégnation au cours de laquelle on imprègne au moins une fois ledit support par un agent B moins polaire que l'agent A, et dans lequel procédé parmi lesdits agents A et B, au moins l'agent B comporte au moins un précurseur de phase active.(b) a second impregnation step during which said support is impregnated at least once with an agent B which is less polar than agent A, and in which process, among said agents A and B, at least agent B comprises at least one active phase precursor.
Le précurseur de phase active, préférentiellement un composé métallique, peut être sélectionné dans le groupe composé des éléments Fe, Ni, Co, Cu, Pt, Pd, Rh, Ru, Ir. Ledit précurseur peut être choisi avantageusement parmi les sels et les composés organo-métalliques desdits éléments.The active phase precursor, preferably a metallic compound, can be selected from the group composed of the elements Fe, Ni, Co, Cu, Pt, Pd, Rh, Ru, Ir. Said precursor can be advantageously chosen from salts and compounds organo-metallic of said elements.
Encore un autre objet de le présente invention est le catalyseur susceptible d'être obtenu par ledit procédé de préparation d'un catalyseur.Yet another object of the present invention is the catalyst capable of being obtained by said process for the preparation of a catalyst.
Encore un autre objet de la présente invention est l'utilisation du catalyseur obtenu par ledit procédé pour catalyser des réactions chimiques, telles que l'oxydation du méthane ou d'autres hydrocarbures, ou l'oxydation du monoxyde de carbone. Description des figuresYet another object of the present invention is the use of the catalyst obtained by said process for catalyzing chemical reactions, such as the oxidation of methane or other hydrocarbons, or the oxidation of carbon monoxide. Description of the figures
La figure 1 montre de façon schématique deux profils de la localisation macroscopique de la phase active par rapport au support dans des catalyseurs selon l'état de la technique, (a) : dépôt en croûte, (b) : dépôt au centre, (c) : dépôt uniforme.FIG. 1 schematically shows two profiles of the macroscopic localization of the active phase relative to the support in catalysts according to the state of the art, (a): crust deposition, (b): deposition in the center, (c ): uniform deposit.
La figure 2 montre de façon schématique la localisation de la phase active dans un catalyseur.Figure 2 shows schematically the location of the active phase in a catalyst.
(a) Catalyseur selon l'état de la technique, imprégné par la méthode classique. La phase active se trouve sur les zones hydrophiles (à l'intérieur des pores).(a) Catalyst according to the state of the art, impregnated by the conventional method. The active phase is found on hydrophilic areas (inside the pores).
(b) Catalyseur selon l'invention, comportant un support aux propriétés hydrophile / hydrophobe, imprégné par la méthode d'imprégnation bi-phasique. La phase active se trouve sur les zone hydrophobes (à l'extérieur des pores).(b) Catalyst according to the invention, comprising a support with hydrophilic / hydrophobic properties, impregnated by the two-phase impregnation method. The active phase is found on the hydrophobic zones (outside the pores).
La figure 3 montre la conversion de CH4 en CO2 en fonction de la température de réaction pour une vitesse spatiale horaire de 15 000 h"1 sur les catalyseurs Pd(0)/β-SiC préparés par imprégnation classique (points noirs) et biphasique (cercles ouverts).FIG. 3 shows the conversion of CH 4 to CO 2 as a function of the reaction temperature for an hourly space velocity of 15,000 h −1 on the Pd (0) / β-SiC catalysts prepared by conventional impregnation (black dots) and biphasic (open circles).
La figure 4 montre un agrandissement de la figure 3 mettant en évidence les températures de demi-conversion.Figure 4 shows an enlargement of Figure 3 highlighting the half-conversion temperatures.
La figure 5 montre la conversion de CH en CO2 en fonction de la température de réaction pour une vitesse spatiale horaire de 40 000 h"1 sur les catalyseurs Pd(0)/β-SiC préparés par imprégnation classique (points noirs) et biphasique (cercles ouverts).FIG. 5 shows the conversion of CH into CO 2 as a function of the reaction temperature for an hourly space velocity of 40,000 h -1 on the Pd (0) / β-SiC catalysts prepared by conventional impregnation (black dots) and biphasic (open circles).
La figure 6 montre un agrandissement de la figure 5 mettant en évidence les températures de demi-conversion. La figure 7 montre la conversion de CH4 en CO2 en fonction de la température de réaction pour une vitesse spatiale horaire de 200 000 h"1 sur les catalyseurs Pd(0)/β-SiC préparés par imprégnation classique (points noirs) et biphasique (cercles ouverts).Figure 6 shows an enlargement of Figure 5 highlighting the half-conversion temperatures. FIG. 7 shows the conversion of CH4 to CO 2 as a function of the reaction temperature for an hourly space velocity of 200,000 h −1 on the Pd (0) / β-SiC catalysts prepared by conventional impregnation (black dots) and biphasic (open circles).
La figure 8 montre un agrandissement de la figure 7 mettant en évidence les températures de demi-conversion.Figure 8 shows an enlargement of Figure 7 highlighting the half-conversion temperatures.
La figure 9 montre la distribution de la taille de macropores dans deux supports de β- SiC qui conviennent à la réalisation de l'invention.Figure 9 shows the size distribution of macropores in two β-SiC supports which are suitable for carrying out the invention.
Description de l'inventionDescription of the invention
Dans le cadre de la présente invention, le problème posé est résolu à l'aide d'une méthode d'imprégnation appelée "imprégnation bi-phasique". Cette méthode d'imprégnation, dont le principe est décrit dans les documents US 5,700,753, EP 133 108 Al, EP 623 387 A, WO 00/67902 et WO 00/29107, consiste à saturer d'une manière sélective, par un choix judicieux de l'agent, soit les zones hydrophiles soit les zones hydrophobes du support afin de pouvoir déposer sélectivement et ainsi localiser le composé précurseur formant la phase active, soit sur les zones hydrophobes, soit sur les zones hydrophiles en fonction de la réaction visée. La méthode permet ainsi le contrôle de la localisation de la phase active d'une manière microscopique par rapport à la matrice du support et non classiquement de manière macroscopique comme décrit ci- dessus.In the context of the present invention, the problem posed is solved by means of an impregnation method called "two-phase impregnation". This impregnation method, the principle of which is described in the documents US Pat. of the agent, either the hydrophilic zones or the hydrophobic zones of the support in order to be able to selectively deposit and thus locate the precursor compound forming the active phase, either on the hydrophobic zones, or on the hydrophilic zones depending on the intended reaction. The method thus makes it possible to control the localization of the active phase in a microscopic manner relative to the matrix of the support and not conventionally in a macroscopic manner as described above.
On entend ici par « agent polaire » une molécule possédant un moment dipolaire permanent. Un agent X est moins polaire qu'un agent Y, si le moment dipolaire permanent de l'agent X est supérieur à celui de l'agent Y. A titre d'exemple, l'eau est un agent polaire, et le toluène est un agent moins polaire que l'eau.The term “polar agent” is understood here to mean a molecule having a permanent dipole moment. Agent X is less polar than Agent Y, if the permanent dipole moment of Agent X is greater than that of Agent Y. For example, water is a polar agent, and toluene is a less polar agent than water.
La présente invention s'applique aux catalyseurs fabriqués sur un support en β-SiC possédant deux fonctions distinctes de surface : hydrophobe et hydrophile. Tout support de catalyseur en β-SiC présentant ces deux fonctions peut convenir, à condition de présenter une porosité et une surface spécifique, déterminée par la méthode BET d'adsorption d'azote, suffisantes, c'est-à-dire au moins 1 m2/g, et préférentiellement au moins 2 m2/g. Avantageusement, le support présente une surface spécifique comprise entre 1 et 100 m2/g. On préfère les supports ayant une surface spécifique supérieure à 10 m2/g, et préférentiellement supérieure à 20 m2/g. Cette surface spécifique est due à la présence de pores. On distingue trois types de pores : les micropores d'une taille moyenne typiquement inférieure à 4 nm, les mesopores d'une taille typiquement comprise entre 4 et 50 nm, et les macropores, qui peuvent former des réseaux, et dont le diamètre est typiquement supérieur à 50 nm. Dans le cadre de la présente invention, on préfère des supports dont la porosité totale, mesurée par l'adsorption d'azote, est essentiellement constituée de mésopores entre 4 et 40 nm et d'un système macroporeux avec un diamètre moyen compris entre 0,05 et 100 μm, préférentiellement entre 0,05 et 10 μm, et encore plus préférentiellement entre 0,05 et 1 μm. La distribution de la taille des pores est mise en évidence par pénétration de mercure. Les pores peuvent aussi être directement observé par microscopie électronique à balayage. Avantageusement, la distribution de la taille des macropores se situe entre 0,06 et 0,4 μm, et encore plus préférentiellement entre 0,06 et 0,2 μm.The present invention applies to catalysts manufactured on a β-SiC support having two distinct surface functions: hydrophobic and hydrophilic. Any β-SiC catalyst support having these two functions may be suitable, provided that they have sufficient porosity and a specific surface, determined by the BET method of nitrogen adsorption, that is to say at least 1 m 2 / g, and preferably at minus 2 m 2 / g. Advantageously, the support has a specific surface of between 1 and 100 m 2 / g. The supports are preferred having a specific surface greater than 10 m 2 / g, and preferably greater than 20 m 2 / g. This specific surface is due to the presence of pores. There are three types of pores: micropores with an average size typically less than 4 nm, mesopores with a size typically between 4 and 50 nm, and macropores, which can form networks, and whose diameter is typically greater than 50 nm. In the context of the present invention, supports are preferred whose total porosity, measured by nitrogen adsorption, essentially consists of mesopores between 4 and 40 nm and a macroporous system with an average diameter between 0, 05 and 100 μm, preferably between 0.05 and 10 μm, and even more preferably between 0.05 and 1 μm. The pore size distribution is demonstrated by penetration of mercury. The pores can also be directly observed by scanning electron microscopy. Advantageously, the size distribution of the macropores is between 0.06 and 0.4 μm, and even more preferably between 0.06 and 0.2 μm.
Dans un mode de réalisation préféré de la présente invention, on utilise un carbure de silicium en β-SiC sous forme d'extradés ou de billes qui est préparé en faisant appel à l'une quelconque des techniques de synthèse décrites dans les demandes de brevets EP 0 313 480 A, EP 0440 569 A, EP 0 511 919 A, EP 0 543 751 A et EP 0 543 752 A.In a preferred embodiment of the present invention, a β-SiC silicon carbide is used in the form of extrudates or beads which is prepared using any of the synthesis techniques described in patent applications EP 0 313 480 A, EP 0440 569 A, EP 0 511 919 A, EP 0 543 751 A and EP 0 543 752 A.
La surface du carbure de silicium (β-SiC) préparé selon l'une des références indiquées ci-dessus est constituée de deux types de zones de nature réactive différente. Une première sorte de zone, de nature hydrophobe, constitue la surface externe du solide et garnit la surface interne des macropores. Ces zones sont essentiellement constituées par des plans de bas indices de Miller, stables et présentant une très faible réactivité vis-à-vis de l'oxygène de l'air. En présence de solvants organiques, le mouillage est réalisé essentiellement sur ces zones hydrophobes. La deuxième sorte de zone est de nature hydrophile et concerne essentiellement les parois internes des mesopores du solide. Ces zones sont constituées de plans atomiques à hauts indices de Miller, et de ce fait riches en défauts de structure. La présence de défauts, à forte réactivité envers les phénomènes d'oxydation-et-d-adsorption mettant en jeu des éléments extérieurs, conduit à l'incorporation en surface des parois internes des pores d'une forte proportion d'oxygène. En présence de solvants aqueux, ces derniers recouvrent préférentiellement ces zones hydrophiles. L'utilisation de la technique de bi- imprégnation permet donc de neutraliser ces mesopores pour le dépôt d'une phase active dans les macropores, ou bien de déposer d'abord une phase active dans les mesopores et puis une autre phase active dans les macropores du β-SiC. Le premier objectif peut être atteint dans un mode de réalisation particulier par un traitement thermique préalable de support sous gaz inerte, qui a pour effet de diminuer la mesoporosité.The surface of the silicon carbide (β-SiC) prepared according to one of the references indicated above consists of two types of zones of different reactive nature. A first sort of zone, hydrophobic in nature, constitutes the external surface of the solid and lines the internal surface of the macropores. These zones are essentially constituted by planes of low Miller indices, stable and having a very low reactivity with respect to the oxygen of the air. In the presence of organic solvents, wetting is carried out essentially on these hydrophobic zones. The second kind of zone is hydrophilic in nature and essentially concerns the internal walls of the solid mesopores. These zones consist of atomic planes with high Miller indices, and therefore rich in structural defects. The presence of faults, with high reactivity towards oxidation-and-d-adsorption phenomena involving external elements, leads to the incorporation on the surface of the internal walls of the pores of a high proportion of oxygen. In the presence of aqueous solvents, the latter preferably cover these hydrophilic zones. The use of the bi-impregnation technique therefore makes it possible to neutralize these mesopores for the deposition of an active phase in the macropores, or else to deposit first an active phase in the mesopores and then another active phase in the macropores. β-SiC. The first objective can be achieved in a particular embodiment by a preliminary heat treatment of the support under inert gas, which has the effect of reducing the mesoporosity.
On donne ci-dessous une description détaillée du mode d'imprégnation bi-phasique. Le support tel que décrit ci-dessus est imprégné comme décrit ci-dessous, en jouant sur ses propriétés hydrophobe et hydrophile, afin de pouvoir modifier et contrôler la localisation de la phase active par rapport au réseau des pores, afin d'améliorer l'accès des réactifs aux sites actifs et afin de garder le même rendement de réaction tout en diminuant le temps de séjour des réactifs et la porosité du support.A detailed description of the two-phase impregnation mode is given below. The support as described above is impregnated as described below, playing on its hydrophobic and hydrophilic properties, in order to be able to modify and control the location of the active phase with respect to the pore network, in order to improve the access of the reagents to the active sites and in order to keep the same reaction yield while reducing the residence time of the reagents and the porosity of the support.
Le mode d'imprégnation biphasique consiste en deux étapes d'imprégnation successives, la première à l'aide d'un agent polaire A (tel que de l'eau), la seconde à l'aide d'un agent B moins polaire que l'agent A, et notamment d'un liquide organique apolaire. Dans les deux étapes, les agents peuvent être avantageusement des liquides. Lesdits liquides peuvent être des solutions, et peuvent notamment contenir des sels métalliques.The biphasic impregnation mode consists of two successive impregnation steps, the first using a polar agent A (such as water), the second using a less polar agent B than agent A, and in particular of an apolar organic liquid. In the two stages, the agents can advantageously be liquids. Said liquids can be solutions, and can in particular contain metal salts.
Dans un mode de réalisation préféré, la première étape d'imprégnation consiste à mouiller le support en β-SiC avec de l'eau (préférentiellement de l'eau déminéralisée ou distillée). Dans une réalisation particulièrement avantageuse de l'invention, le volume d'eau est égal ou légèrement supérieur au volume poreux total du solide. Cette opération permet de saturer complètement les zones hydrophiles de la surface du solide qui sont essentiellement localisées à l'intérieur des pores du matériau. L'eau reste ainsi piégée à l'intérieur des pores laissant libre les zones hydrophobes qui constituent la surface externe du solide. Dans un autre mode de réalisation, on utilise lors de cette première étape d'imprégnation un liquide polaire contenant un ou plusieurs composés solubles. Ledit composé soluble peut être un composé métallique. Ledit composé métallique peut jouer le rôle de phase active ou de précurseur de phase active. Après cette première étape d'imprégnation par le liquide polaire, le solide imprégné est séché superficiellement, afin d'éliminer l'humidité de la surface externe du corps, tout en gardant le liquide dans les pores. A titre d'exemple, une température de 50 °C à pression normale convient pour un liquide aqueux ; les conditions précises (température et durée) pour un support donné peuvent être déterminées facilement à l'aide de simples expériences de routine.In a preferred embodiment, the first impregnation step consists of wetting the β-SiC support with water (preferably demineralized or distilled water). In a particularly advantageous embodiment of the invention, the volume of water is equal to or slightly greater than the total pore volume of the solid. This operation makes it possible to completely saturate the hydrophilic zones of the surface of the solid which are essentially located inside the pores of the material. The water thus remains trapped inside the pores leaving free the hydrophobic zones which constitute the external surface of the solid. In another embodiment, a polar liquid containing one or more soluble compounds is used during this first impregnation step. Said soluble compound can be a metallic compound. Said metal compound can play the role of active phase or active phase precursor. After this first step of impregnation with the polar liquid, the impregnated solid is dried superficially, in order to remove the moisture from the external surface of the body, while keeping the liquid in the pores. For example, a temperature of 50 ° C at normal pressure is suitable for an aqueous liquid; the precise conditions (temperature and duration) for a given support can be easily determined using simple routine experiments.
Dans une deuxième étape d'imprégnation, on dépose sur le solide, de préférence dans une solution organique essentiellement apolaire, au moins un précurseur de la phase active. On entend par « précurseur de la phase active » un composé d'un métal, typiquement un sel d'un métal ou un composé organo-métallique, qui forme, après un traitement de calcination suivi éventuellement d'autres traitements tels qu'une réduction, la phase active du catalyseur. Il est souhaitable de sélectionner le solvant de façon à ce que l'affinité du solvant organique avec les zones hydrophobes permette un mouillage parfait de ces dernières, tandis que l'intérieur des pores reste inaccessible en raison de la présence de l'eau imprégnée auparavant. En effet, dû aux interactions fortes existant entre la surface interne des pores du solide (hydrophile) et l'eau piégée dans ceux-ci, l'évaporation de cette dernière lors du séchage est fortement freinée, et l'eau pré-imprégnée constitue de ce fait une barrière de protection des zones hydrophiles. Dans certains cas, on peut utiliser comme précurseur de phase active des composés organo-métalliques liquides à l'état pur.In a second impregnation step, at least one precursor of the active phase is deposited on the solid, preferably in an essentially apolar organic solution. The term “precursor of the active phase” is understood to mean a compound of a metal, typically a salt of a metal or an organometallic compound, which forms, after a calcination treatment optionally followed by other treatments such as reduction , the active phase of the catalyst. It is desirable to select the solvent so that the affinity of the organic solvent with the hydrophobic zones allows perfect wetting of the latter, while the interior of the pores remains inaccessible due to the presence of the water previously impregnated. . In fact, due to the strong interactions existing between the internal surface of the pores of the (hydrophilic) solid and the water trapped in them, the evaporation of the latter during drying is strongly curbed, and the prepreg water constitutes therefore a protective barrier for hydrophilic areas. In certain cases, it is possible to use, as precursor of the active phase, organo-metallic compounds which are liquid in the pure state.
Dans une première étape d'activation, le support imprégné est ensuite séché, par exemple sous air à température ambiante puis à une température avantageusement comprise entre 100°C et 200°C dans une étuve afin de vaporiser le solvant organique. Le solide séché est calciné sous air à une température typiquement comprise entre 200 °C et 500 °C et plus préférablement entre 300 °C et 400 °C pendant une période qui dépend de la charge du four, des caractéristiques du solvant et de celles du support, afin de décomposer le précurseur de la phase active en son oxyde métallique correspondant. Le solide calciné peut être utilisé tel quel en tant que catalyseur. En fonction des utilisations ultérieures, il peut être soumis également à une deuxième étape, optionnelle, d'activation, qui est avantageusement un traitement sous gaz réactif, et préférentiellement une réduction. Lors de cette deuxième étape d'activation, l'oxyde peut être soit réduit sous un flux d'hydrogène H2 pour l'obtention du métal correspondant, soit traité avec d'autres gaz afin d'obtenir la phase active désirée. La phase active ainsi obtenue est localisée essentiellement sur les surfaces constituées des zones hydrophobes du support, i.e. les surfaces à l'extérieur des pores.In a first activation step, the impregnated support is then dried, for example in air at room temperature and then at a temperature advantageously between 100 ° C. and 200 ° C. in an oven in order to vaporize the organic solvent. The dried solid is calcined in air at a temperature typically between 200 ° C and 500 ° C and more preferably between 300 ° C and 400 ° C for a period which depends on the charge of the furnace, the characteristics of the solvent and those of the support, in order to decompose the precursor of the active phase into its corresponding metal oxide. The calcined solid can be used as it is as a catalyst. Depending on the subsequent uses, it can also be subjected to a second, optional, activation step, which is advantageously a treatment under reactive gas, and preferably a reduction. During this second activation step, the oxide can either be reduced under a flow of hydrogen H 2 to obtain the corresponding metal, or treated with other gases in order to obtain the desired active phase. The active phase thus obtained is located essentially on the surfaces made up of the hydrophobic zones of the support, ie the surfaces outside the pores.
En tenant compte de la localisation spécifique des zones hydrophobes et hydrophiles dans le support à base de carbure de silicium, à savoir respectivement à l'extérieur et à l'intérieur des pores du support, la localisation de la phase active peut être schématisée par rapport à la porosité du support comme indiqué sur la figure 2.By taking into account the specific localization of the hydrophobic and hydrophilic zones in the support based on silicon carbide, namely respectively outside and inside the pores of the support, the localization of the active phase can be diagrammatically compared the porosity of the support as shown in Figure 2.
On décrit ci-dessous les principales caractéristiques du catalyseur obtenu, ainsi que ses domaines d'applications. Dans le cadre de la présente invention, la phase active peut être constituée de n'importe quel métal possédant un sel soluble dans un solvant peu polaire, ou encore un composé organo-métallique suffisamment stable. Parmi ces métaux, on peut citer notamment : Co, Ni, Fe, Cu, Pt, Pd, Rh, Ru, Ir. La concentration de ladite phase active peut être comprise dans une fourchette relativement large de la dizaine de ppm (part par million, par rapport à la masse) jusqu'à plusieurs dizaines de pourcents (par rapport à la masse), en fonction de la réaction visée. Avantageusement, elle est comprise entre 0,1 et 5 % par rapport à la masse du catalyseur.The main characteristics of the catalyst obtained are described below, as well as its fields of application. In the context of the present invention, the active phase can consist of any metal having a salt soluble in a weakly polar solvent, or alternatively an organometallic compound which is sufficiently stable. Among these metals, there may be mentioned in particular: Co, Ni, Fe, Cu, Pt, Pd, Rh, Ru, Ir. The concentration of said active phase can be included in a relatively wide range of around ten ppm (parts per million , relative to the mass) up to several tens of percent (relative to the mass), depending on the intended reaction. Advantageously, it is between 0.1 and 5% relative to the mass of the catalyst.
Une autre variante mettant à profit l'avantage qu'offre cette méthode d'imprégnation concerne le dépôt de deux composés différents sur le même support en utilisant pour chacune d'elles un solvant de polarité adéquate et permettant ainsi un contrôle précis de leur localisation respective. La méthode d'imprégnation bi-phasique décrite peut également s'appliquer pour déposer successivement deux composés formant chacun une phase active, utilisées séparément en raison de leurs propriétés catalytiques différentes et particulières, mais localisées sur un même support.Another variant taking advantage of the advantage offered by this impregnation method concerns the deposition of two different compounds on the same support, using for each of them a solvent of adequate polarity and thus allowing precise control of their respective localization. . The two-phase impregnation method described can also be applied to successively deposit two compounds each forming a active phase, used separately because of their different and particular catalytic properties, but located on the same support.
Le catalyseur ainsi préparé peut être utilisé sous différentes conditions et dans divers milieux réactionnels. Plus particulièrement, il peut être utilisé pour les réactions ayant une vitesse de passage de réactifs très rapide, i.e. pour la dépollution des gaz d'échappement des véhicules à moteur, ou pour les réactions où la sélectivité globale pourrait être affectée par des réactions secondaires entre les produits et un des réactifs en excès, lors de la diffusion des produits depuis les sites actifs vers la surface externe du support.The catalyst thus prepared can be used under different conditions and in various reaction media. More particularly, it can be used for reactions having a very rapid rate of passage of reagents, ie for the depollution of exhaust gases from motor vehicles, or for reactions where the overall selectivity could be affected by secondary reactions between the products and one of the excess reagents, during the diffusion of the products from the active sites to the external surface of the support.
La présente invention présente de nombreux avantages :The present invention has many advantages:
Tout d'abord, l'accessibilité améliorée des sites actifs pour les réactifs en phase gazeuse ou en phase liquide permet une augmentation sensible du rendement global de la réaction. En effet, lorsque la phase active est déposée directement sur la surface externe du support ou dans une macroporosité, l'accessibilité des sites actifs pour les réactifs en phase gaz ou liquide peut être augmentée d'une manière considérable ; cela augmente le rendement de la réaction.First, the improved accessibility of active sites for reactants in the gas phase or in the liquid phase allows a significant increase in the overall yield of the reaction. Indeed, when the active phase is deposited directly on the external surface of the support or in a macroporosity, the accessibility of the active sites for the reactants in gas or liquid phase can be considerably increased; this increases the yield of the reaction.
Puis, le temps de séjour extrêmement court entre la phase active et les réactifs ainsi que les produits de réaction permet de diminuer d'une manière sensible la formation des produits secondaires. En effet, lorsque l'un des réactifs est en excès et peut réagir de nouveau avec un des produits formés au cours de la réaction, la durée de migration des produits à travers la porosité du support pour atteindre la phase gaz ou liquide, ou plus généralement s'échapper du grain de catalyseur, peut être un facteur très important dans la sélectivité globale de la réaction.Then, the extremely short residence time between the active phase and the reactants as well as the reaction products makes it possible to appreciably reduce the formation of the secondary products. In fact, when one of the reactants is in excess and can react again with one of the products formed during the reaction, the duration of migration of the products through the porosity of the support to reach the gas or liquid phase, or more generally escaping from the catalyst grain, can be a very important factor in the overall selectivity of the reaction.
Puis, le fait de localiser la phase active sur une zone hydrophobe possède un avantage certain lorsque l'un des produits de la réaction est de l'eau. L'eau peut induire des modifications-indésirables à la phase active en raison de son caractère-oxydant. En - effet, lorsque la phase active est localisée sur les zones hydrophiles, l'eau formée peut s'adsorber sur les sites actifs du catalyseur et oxyder ce dernier, tandis que l'adsorption d'eau est évitée lorsque la phase active est localisée sur les zones hydrophobes. Cet avantage est également significatif lorsque la réaction s'effectue en présence d'eau ou de tout autre solvant interagissant fortement avec les zones hydrophiles et possédant des propriétés oxydantes dans le milieu réactionnel.Then, the fact of locating the active phase on a hydrophobic zone has a certain advantage when one of the products of the reaction is water. Water can induce undesirable modifications to the active phase due to its oxidizing character. In - indeed, when the active phase is located on the hydrophilic areas, the water formed can adsorb on the active sites of the catalyst and oxidize the latter, while water adsorption is avoided when the active phase is located on the hydrophobic areas. This advantage is also significant when the reaction is carried out in the presence of water or any other solvent which interacts strongly with the hydrophilic zones and which has oxidizing properties in the reaction medium.
Et finalement, la méthode de dépôt selon l'invention permet également de diminuer d'une manière considérable la teneur de la phase active nécessaire par rapport à celle utilisée dans les imprégnations en croûte. De ce fait, la perte de la phase active, qui peut avoir lieu soit par frittage, soit par attrition durant l'imprégnation ou plus généralement durant la ou les phases de préparation ou d'activation du catalyseur ainsi que durant le test catalytique, est considérablement réduite ; cela augmente la durée de vie du catalyseur.And finally, the deposition method according to the invention also makes it possible to considerably reduce the content of the active phase necessary compared to that used in the crust impregnations. Therefore, the loss of the active phase, which can take place either by sintering or by attrition during the impregnation or more generally during the phase or phases of preparation or activation of the catalyst as well as during the catalytic test, is considerably reduced; this increases the service life of the catalyst.
Les catalyseurs préparés dans le cadre de la présente invention allient les avantages acquis sur les supports macroscopiques classiques et ceux d'une meilleure accessibilité des réactifs aux sites actifs et d'une meilleure évacuation des produits. Ils permettant ainsi un gain non négligeable des rendements des différentes réactions tout en maintenant une dispersion maximale de la phase active pour ne pas nuire au rendement global de la réaction. Le mode d'exécution préféré utilisant des supports en extradés, billes ou pastilles de β-SiC permet en plus de bénéficier des avantages spécifiques associés à ce type de supports.The catalysts prepared in the context of the present invention combine the advantages acquired on conventional macroscopic supports with those of better accessibility of the reagents to the active sites and better evacuation of the products. They thus allow a non-negligible gain in the yields of the various reactions while maintaining a maximum dispersion of the active phase so as not to harm the overall yield of the reaction. The preferred embodiment using extruded supports, beads or pellets of β-SiC also makes it possible to benefit from the specific advantages associated with this type of support.
Le catalyseur selon l'invention peut être utilisé dans divers domaines, tels que l'industrie chimique ou pétrochimique. A titre d'exemple, il peut catalyser l'oxydation du méthane ou l'oxydation du monoxyde de carbone. Il peut être utilisé également dans les réactions de dépollution des gaz d'échappement de moteurs à combustion interne (notamment ceux fonctionnant avec des carburants liquides tels que l'essence ou le gasoil) où il permet d'obtenir un meilleur rendement, grâce à. un temps de contact très court, et une très bonne accessibilité des sites actifs du catalyseur par les réactifs. Pour compléter la description précédente, on donne ci-après, à titre non limitatif, une série d'exemples illustrant l'invention.The catalyst according to the invention can be used in various fields, such as the chemical or petrochemical industry. For example, it can catalyze the oxidation of methane or the oxidation of carbon monoxide. It can also be used in the depollution reactions of exhaust gases from internal combustion engines (in particular those operating with liquid fuels such as petrol or diesel) where it makes it possible to obtain a better efficiency, thanks to. a very short contact time, and very good accessibility of the active sites of the catalyst by the reagents. To complete the preceding description, a series of examples illustrating the invention is given below, without implied limitation.
ExemplesExamples
Exemple 1: Préparation du catalyseur par imprégnation biphasiqueEXAMPLE 1 Preparation of the Catalyst by Biphasic Impregnation
Cet exemple illustre d'une manière détaillée l'imprégnation d'une phase active à base de platine par la méthode d'imprégnation bi-phasique sur un support à base d'extradés de carbure de silicium (β-SiC).This example illustrates in a detailed manner the impregnation of an active phase based on platinum by the two-phase impregnation method on a support based on extruded silicon carbide (β-SiC).
Dans une première étape, le support à base d'extradés de carbure de silicium β-SiC est préalablement imprégné avec une solution d'eau distillée dont le volume est égal au volume poreux du support, afin de bloquer l'entrée des pores du solide. 5 g de carbure de silicium (surface spécifique BET 25 m2/g) sont donc dans un premier temps pré- imprégnés avec 3 mL d'eau distillée et puis séchés pendant 5 minutes à 50 °C. Le matériau est dans une deuxième étape imprégné selon la méthode de la goutte par une solution de bis-acétylacétonate de platine dans du toluène (solvant apolaire) à raison de 2 % en poids de platine par rapport au support carbure de silicium (soit 0,196 g d'acétylacétonate, correspondant à 0,100 g de Pt, dans 3 mL de toluène). Dans une troisième étape, le solide obtenu est séché à l'air à température ambiante puis à 150 °C dans une étuve pendant 2 heures. Il est calciné ensuite sous air à 350 °C pendant 2 heures afin de transformer le sel de platine en son oxyde correspondant, puis réduit à 400°C sous flux d'hydrogène pendant 2 heures pour former le platine métallique. Le platine métallique Pt se trouve alors localisé à l'extérieur des pores du carbure de silicium.In a first step, the support based on extruded silicon carbide β-SiC is previously impregnated with a solution of distilled water whose volume is equal to the pore volume of the support, in order to block the entry of the pores of the solid. . 5 g of silicon carbide (BET specific surface 25 m 2 / g) are therefore first pre-impregnated with 3 mL of distilled water and then dried for 5 minutes at 50 ° C. The material is in a second step impregnated according to the drop method with a solution of platinum bis-acetylacetonate in toluene (non-polar solvent) at a rate of 2% by weight of platinum relative to the silicon carbide support (i.e. 0.196 g acetylacetonate, corresponding to 0.100 g of Pt, in 3 mL of toluene). In a third step, the solid obtained is dried in air at room temperature and then at 150 ° C in an oven for 2 hours. It is then calcined in air at 350 ° C for 2 hours to transform the platinum salt into its corresponding oxide, then reduced to 400 ° C under a stream of hydrogen for 2 hours to form the metallic platinum. The metallic platinum Pt is then located outside the pores of the silicon carbide.
Exemple 2: Utilisation du catalyseur obtenu par imprégnation biphasiqueExample 2 Use of the catalyst obtained by biphasic impregnation
Cet exemple illustre dans le cas de l'oxydation totale du méthane en dioxyde de carbone l'influence du mode d'imprégnation, à savoir purement aqueux pour localiser la phase active dans les pores du support, et bi-phasique pour localiser ladite phase active à l'extérieur de la mésoporosité du support.This example illustrates in the case of the total oxidation of methane to carbon dioxide the influence of the impregnation mode, namely purely aqueous to locate the active phase in the pores of the support, and two-phase to locate said active phase outside the mesoporosity of the support.
Deux catalyseurs à base de palladium métal supporté sur grains de carbure de silicium (β-SiC, grains de diamètre compris entre 0.4 mm et 1 mm, surface spécifique 25 m2/g) sont préparés avec une teneur en palladium métal de 1 % en masse du support carbure de silicium : pour l'un des deux catalyseurs, on utilise la méthode d'imprégnation purement aqueuse selon l'état de la technique, tandis que pour l'autre, on utilise la méthode d'imprégnation bi-phasique selon l'invention.Two catalysts based on palladium metal supported on grains of silicon carbide (β-SiC, grains of diameter between 0.4 mm and 1 mm, specific surface 25 m 2 / g) are prepared with a palladium metal content of 1% in mass of the silicon carbide support: for one of the two catalysts, the purely aqueous impregnation method is used according to the state of the art, while for the other, the two-phase impregnation method is used according to the invention.
L'imprégnation purement aqueuse est réalisée en imprégnant les grains de carbure de silicium (β-SiC) avec une solution aqueuse de Pdπ(NO3).H2O. Après séchage sous air à température ambiante, le solide est placé à l'étuve à 100°C pendant 2 heures. Le solide séché est ensuite calciné sous air à 350 °C pendant 2 heures afin de former l'oxyde de palladium PdO. Le catalyseur palladium métal supporté sur carbure de silicium est obtenu par réduction de son homologue oxyde à 400 °C sous hydrogène pendant 2 heures. Cette imprégnation purement aqueuse conduit à l'obtention de la phase palladium Pd(0) localisée dans la porosité du support à base de carbure de silicium.The purely aqueous impregnation is carried out by impregnating the grains of silicon carbide (β-SiC) with an aqueous solution of Pd π (NO 3 ) .H 2 O. After drying in air at room temperature, the solid is placed at 1 oven at 100 ° C for 2 hours. The dried solid is then calcined in air at 350 ° C. for 2 hours in order to form the palladium oxide PdO. The palladium metal catalyst supported on silicon carbide is obtained by reduction of its oxide counterpart at 400 ° C. under hydrogen for 2 hours. This purely aqueous impregnation leads to obtaining the palladium phase Pd (0) localized in the porosity of the support based on silicon carbide.
L'imprégnation bi-phasique du support carbure de silicium (β-SiC) est réalisée en imprégnant tout d'abord le support avec une solution aqueuse d'un volume égal au volume poreux dudit support. Après séchage à 50 °C pendant 5 minutes, 1 % en masse de palladium est alors déposé sur le support sous forme d'acétylacétonate de palladium (C10H4θ Pd) dans du toluène. Le matériau est ensuite soumis aux mêmes traitements que le catalyseur préparé par imprégnation aqueuse traditionnelle. L'oxyde de palladium est alors réduit en palladium métallique par traitement thermique sous hydrogène à 400 °C pendant 2 heures. Les particules de palladium métallique sont alors localisées à l'extérieur des pores du carbure de silicium.The two-phase impregnation of the silicon carbide support (β-SiC) is carried out by first impregnating the support with an aqueous solution of a volume equal to the pore volume of said support. After drying at 50 ° C for 5 minutes, 1% by mass of palladium is then deposited on the support in the form of palladium acetylacetonate (C 10 H 4 θ Pd) in toluene. The material is then subjected to the same treatments as the catalyst prepared by traditional aqueous impregnation. The palladium oxide is then reduced to metallic palladium by heat treatment under hydrogen at 400 ° C. for 2 hours. The metallic palladium particles are then located outside the pores of the silicon carbide.
La réaction d'oxydation totale du méthane en dioxyde de carbone sur les deux catalyseurs dont les modes de préparation sont détaillées ci-dessus est réalisée dans les conditions-réactionnelles reportées dans le Tableau 1. Tableau 1 :The total oxidation reaction of methane to carbon dioxide on the two catalysts, the methods of preparation of which are detailed above, is carried out under the reaction conditions given in Table 1. Table 1:
Conditions réactionnelles de la réaction d'oxydation totale du méthane en dioxyde de carbone sur catalyseurs palladium (0) supportés sur grains de carbure de silicium.Reaction conditions for the total oxidation reaction of methane to carbon dioxide on palladium (0) catalysts supported on grains of silicon carbide.
La vitesse spatiale volumique horaire (en anglais « gaz hourly space velocity ») est définie comme étant le rapport entre le flux total et le volume de catalyseur.The hourly space velocity (in English "gas hourly space velocity") is defined as being the ratio between the total flux and the volume of catalyst.
L'influence du mode d'imprégnation de la phase active lors de la préparation du catalyseur sur l'activité catalytique en combustion du méthane est reportée sur la Figure 3. Le Tableau 2 montre les températures de demi-conversion obtenues sur les deux catalyseurs en fonction de la vitesse spatiale volumique horaire du flux contenant le méthane et l'oxygène à raison de respectivement 1 % et 4 % en volume. A faible vitesse spatiale volumique horaire (15000 h"1), la température de demi-conversion sur le catalyseur préparé par la méthode d'imprégnation bi-phasique est de 300 °C comparée à 316 °C sur le catalyseur préparé par la méthode d'imprégnation classique. Cette différence s'accentue lorsque la vitesse spatiale volumique horaire augmente, et l'écart de température est de 23 °C pour une vitesse spatiale de 40000 h" . Cet écart de température atteint 57 °C lorsque l'oxydation totale du méthane est réalisée à très forte vitesse spatiale volumique horaire, à savoir 200000 h"1.The influence of the mode of impregnation of the active phase during the preparation of the catalyst on the catalytic activity in combustion of methane is reported in Figure 3. Table 2 shows the half-conversion temperatures obtained on the two catalysts. function of the hourly space volume velocity of the flow containing methane and oxygen at a rate of 1% and 4% by volume respectively. At low hourly space volume velocity (15,000 h -1 ), the half-conversion temperature on the catalyst prepared by the two-phase impregnation method is 300 ° C. compared to 316 ° C. on the catalyst prepared by the method d "classic impregnation. This difference increases when the hourly space velocity increases, and the temperature difference is 23 ° C. for a space velocity of 40,000 h " . This gap of temperature reaches 57 ° C. when the total oxidation of methane is carried out at very high hourly space volume velocity, namely 200,000 h "1 .
Tableau 2 : Températures de demi-conversion obtenues selon le mode d'imprégnation du catalyseur en fonction de la vitesse spatiale volumique horaire de la réaction.Table 2: Half-conversion temperatures obtained according to the method of impregnation of the catalyst as a function of the hourly space volume velocity of the reaction.
On note que le catalyseur préparé par imprégnation bi-phasique selon l'invention présente une meilleure performance, c'est-à-dire une température de demi-conversion significativement plus basse que le catalyseur préparé par imprégnation aqueuse monophasique selon l'état de la technique. Cette performance améliorée du catalyseur selon l'invention préparé par imprégnation bi-phasique peut être attribuée à la présence du palladium sur la surface externe du support ; le palladium, qui forme la phase active du catalyseur, présente ainsi une meilleure accessibilité vis-à-vis du réactif à transformer. La localisation de la phase active en dehors de la porosité du support carbure de silicium permet ainsi de réduire considérablement les phénomènes de diffusion et d'obtenir à températures identiques des conversions de CH4 supérieures à celles obtenues avec un catalyseur préparé par la méthode d'imprégnation classique purement aqueuse. Exemple 3 : Caractérisation des macropores dans un support en β-SiCIt is noted that the catalyst prepared by two-phase impregnation according to the invention has better performance, that is to say a significantly lower half-conversion temperature than the catalyst prepared by single-phase aqueous impregnation according to the state of the technical. This improved performance of the catalyst according to the invention prepared by two-phase impregnation can be attributed to the presence of palladium on the external surface of the support; palladium, which forms the active phase of the catalyst, thus has better accessibility vis-à-vis the reagent to be transformed. The localization of the active phase outside the porosity of the silicon carbide support thus makes it possible to considerably reduce the diffusion phenomena and to obtain, at identical temperatures, CH 4 conversions higher than those obtained with a catalyst prepared by the method of purely aqueous classic impregnation. Example 3 Characterization of the Macropores in a β-SiC Support
Cet exemple montre la distribution des macropores dans deux supports de β-SiC qui conviennent bien à la réalisation de l'invention, voir la figure 9. Il s'agit d'extradés en β-SiC. Le support Zl a été fabriqué à partir de Si -f C + résine, le support Z2 avec un ajout de éthanol. On constate que le support Zl a une distribution centrée autour d'environ 0,06 μm, alors que le support Z2 a une distribution centrée autour d'environ 0,11 μm. This example shows the distribution of the macropores in two supports of β-SiC which are very suitable for carrying out the invention, see FIG. 9. They are extraded into β-SiC. Support Z1 was made from Si -f C + resin, support Z2 with the addition of ethanol. It can be seen that the support Z1 has a distribution centered around around 0.06 μm, while the support Z2 has a distribution centered around around 0.11 μm.

Claims

Revendications claims
1. Utilisation d'un catalyseur pour catalyse hétérogène comportant un support en β- SiC et au moins une phase active, ledit catalyseur étant susceptible d'être obtenu par un procédé comportant au moins les étapes suivantes :1. Use of a catalyst for heterogeneous catalysis comprising a β-SiC support and at least one active phase, said catalyst being capable of being obtained by a process comprising at least the following steps:
(a) l'imprégnation dudit support ayant une surface spécifique, déterminée par la méthode BET d'adsorption d'azote à la température de l'azote liquide selon la norme NF X 11-621, au moins égale à 1 m /g, avec au moins un précurseur de phase active, ladite imprégnation étant effectuée par un procédé d'imprégnation comportant au moins une première étape d'imprégnation au cours de laquelle on imprègne au moins une fois ledit support par un agent polaire A, et une deuxième étape d'imprégnation au cours de laquelle on imprègne au moins une fois ledit support par un agent B moins polaire que l'agent A, sachant qu'au moins l'agent B comporte un précurseur de phase active,(a) the impregnation of said support having a specific surface, determined by the BET method of nitrogen adsorption at the temperature of liquid nitrogen according to standard NF X 11-621, at least equal to 1 m / g, with at least one active phase precursor, said impregnation being carried out by an impregnation process comprising at least a first impregnation step during which said support is impregnated at least once with a polar agent A, and a second step impregnation during which said support is impregnated at least once with a less polar agent B than agent A, knowing that at least agent B comprises an active phase precursor,
(b) la décomposition thermique dudit précurseur, ladite utilisation étant une utilisation pour catalyser des réactions chimiques sélectionnées parmi l'oxydation du méthane ou d'autres hydrocarbures, l'oxydation du monoxyde de carbone, ou une utilisation pour catalyser la dépollution de gaz d'échappement de moteurs à combustion interne.(b) thermal decomposition of said precursor, said use being a use for catalyzing chemical reactions selected from the oxidation of methane or other hydrocarbons, the oxidation of carbon monoxide, or a use to catalyze the depollution of d gases of internal combustion engines.
2. Utilisation selon la revendication 1, caractérisée en ce que ledit précurseur de phase active est un composé métallique.2. Use according to claim 1, characterized in that said active phase precursor is a metallic compound.
3. Utilisation selon la revendication 2, caractérisée en ce que le métal contenu dans ledit composé métallique de l'agent A et ou de l'agent B est sélectionné dans le groupe composé des éléments Fe, Ni, Co, Cu, Pt, Pd, Rh, Ru, Ir.3. Use according to claim 2, characterized in that the metal contained in said metallic compound of agent A and or of agent B is selected from the group composed of the elements Fe, Ni, Co, Cu, Pt, Pd , Rh, Ru, Ir.
4. Utilisation selon la revendication 2 ou 3, caractérisée en ce que ledit composé métallique contenu dans lesdits agents est soit un sel dissout dans un solvant, soit un composé organo-métallique, 4. Use according to claim 2 or 3, characterized in that said metallic compound contained in said agents is either a salt dissolved in a solvent, or an organometallic compound,
5. Utilisation selon la revendication 4, caractérisée en ce que ledit composé organo- métallique est soit dissout dans un solvant, soit utilisé à l'état pur.5. Use according to claim 4, characterized in that said organometallic compound is either dissolved in a solvent, or used in the pure state.
6. Utilisation selon une quelconque des revendications 1 à 5, caractérisée en ce que ledit support se présente sous forme de billes, fibres, tubes, filaments, feutres, extradés, mousses, monolithes ou pastilles.6. Use according to any one of claims 1 to 5, characterized in that said support is in the form of balls, fibers, tubes, filaments, felts, extruded, foams, monoliths or pellets.
7. Utilisation selon une quelconque des revendications 1 à 6, caractérisée en ce que ledit support a une surface spécifique BET supérieure à 2 m2/g, plus préférentiellement supérieure à 10 m2/g et encore plus préférentiellement supérieure à 20 m2/g.7. Use according to any one of claims 1 to 6, characterized in that said support has a BET specific surface greater than 2 m 2 / g, more preferably greater than 10 m 2 / g and even more preferably greater than 20 m 2 / g.
8. Utilisation selon une quelconque des revendications 1 à 7, caractérisée en ce que ledit support possède une surface spécifique BET comprise entre 1 m2/g et 100 m2/g.8. Use according to any one of claims 1 to 7, characterized in that said support has a BET specific surface of between 1 m 2 / g and 100 m 2 / g.
9. Utilisation selon une quelconque des revendications 1 à 8, caractérisée en ce que ledit support comporte des macropores d'une taille comprise entre 0,05 et 10 μm, et optionnellement en plus des mesopores d'une taille comprise entre 4 et 40 nm.9. Use according to any one of claims 1 to 8, characterized in that said support comprises macropores with a size between 0.05 and 10 μm, and optionally in addition to the mesopores with a size between 4 and 40 nm .
10. Utilisation selon la revendication 9, caractérisé en ce que lesdites macropores ont une taille comprise entre 0,05 et 1 μm.10. Use according to claim 9, characterized in that said macropores have a size between 0.05 and 1 μm.
11. Utilisation selon une des revendications 1 à 10, caractérisée en ce que le maximum de la distribution de la taille desdites macropores se situe entre 0,06 et11. Use according to one of claims 1 to 10, characterized in that the maximum of the size distribution of said macropores is between 0.06 and
0,4 μm, et de préférentiellement entre 0,06 et 0,2 μm.0.4 μm, and preferably between 0.06 and 0.2 μm.
12. Utilisation selon une quelconque des revendications 1 à 11, caractérisée en ce que le procédé d'imprégnation (a) comporte en plus au moins une étape de séchage après la première et / ou après la deuxième étape d'imprégnation. 12. Use according to any one of claims 1 to 11, characterized in that the impregnation process (a) further comprises at least one drying step after the first and / or after the second impregnation step.
13. Utilisation selon une quelconque des revendications 1 à 12, caractérisée en ce que le procédé d'imprégnation (a) comporte en plus au moins un traitement préalable du support qui introduit sur la surface dudit support des fonctions hydrophobes et / ou hydrophiles.13. Use according to any one of claims 1 to 12, characterized in that the impregnation process (a) further comprises at least one prior treatment of the support which introduces hydrophobic and / or hydrophilic functions on the surface of said support.
14. Utilisation selon une quelconque des revendications 1 à 13, caractérisée en ce que ledit précurseur forme, lors de sa décomposition thermique, au moins partiellement un oxyde métallique.14. Use according to any one of claims 1 to 13, characterized in that said precursor forms, during its thermal decomposition, at least partially a metal oxide.
15. Utilisation selon la revendication 14, caractérisée en ce que la décomposition thermique dudit précurseur est suivie d'un traitement sous un gaz réactif.15. Use according to claim 14, characterized in that the thermal decomposition of said precursor is followed by a treatment under a reactive gas.
16. Utilisation selon la revendication 14 ou 15, caractérisée en ce que le dit traitement sous un gaz réactif est un traitement de réduction.16. Use according to claim 14 or 15, characterized in that said treatment under a reactive gas is a reduction treatment.
17. Utilisation selon la revendication 16, caractérisée en ce que ledit traitement de réduction a été effectué dans une atmosphère contenant de l'hydrogène H2.17. Use according to claim 16, characterized in that said reduction treatment was carried out in an atmosphere containing hydrogen H 2 .
18. Utilisation selon l'une des revendications 1 à 17, caractérisée en ce que le support séché à l'issue de la dernière étape d'imprégnation est calciné à l'air à une température comprise entre 200 °C et 500 °C, et préférentiellement entre 300 °C et 400 °C.18. Use according to one of claims 1 to 17, characterized in that the support dried after the last impregnation step is calcined in air at a temperature between 200 ° C and 500 ° C, and preferably between 300 ° C and 400 ° C.
19. Procédé d'imprégnation d'un support en β-SiC ayant une surface spécifique, déterminée par la méthode BET d'adsorption d'azote à la température de l'azote liquide selon la norme NF X 11-621, au moins égale à 1 m2/g et comportant comportant des macropores d'une taille comprise entre 0,05 et 10 μm, et optionnellement en plus des mesopores d'une taille comprise entre 4 et 40 nm, , ledit procédé comportant au moins les étapes suivantes : (c) une première étape d'imprégnation au cours de laquelle on imprègne au moins-une fois ledit support par un agent polaire A, (d) une deuxième étape d'imprégnation au cours de laquelle on imprègne au moins une fois ledit support par un agent B moins polaire que l'agent A, et dans lequel procédé parmi lesdits agents A et B, au moins l'agent B comporte au moins un précurseur de phase active.19. Method for impregnating a β-SiC support having a specific surface, determined by the BET method of nitrogen adsorption at the temperature of liquid nitrogen according to standard NF X 11-621, at least equal at 1 m 2 / g and comprising comprising macropores with a size between 0.05 and 10 μm, and optionally in addition to the mesopores with a size between 4 and 40 nm, said method comprising at least the following steps : (c) a first impregnation step during which said support is impregnated at least once with a polar agent A, (d) a second impregnation step during which said support is impregnated at least once with an agent B less polar than agent A, and in which process among said agents A and B, at least agent B comprises at least one active phase precursor.
20. Procédé selon la revendication 19, caractérisé en ce que ledit support a une surface spécifique d'au moins 10 m2/g.20. The method of claim 19, characterized in that said support has a specific surface of at least 10 m 2 / g.
21. Procédé selon la revendication 20, caractérisé en ce que la taille moyenne desdites macropores dudit support est comprise entre 0,05 et 1 μm.21. Method according to claim 20, characterized in that the average size of said macropores of said support is between 0.05 and 1 μm.
22. Procédé selon une des revendications 19 à 21, caractérisé en ce que le maximum de la distribution de la taille desdites macropores se situe entre 0,06 et 0,4 μm, et de préférentiellement entre 0,06 et 0,2 μm.22. Method according to one of claims 19 to 21, characterized in that the maximum of the size distribution of said macropores is between 0.06 and 0.4 microns, and preferably between 0.06 and 0.2 microns.
23. Produit susceptible d'être obtenu à partir du procédé selon une des revendications 23. Product capable of being obtained from the process according to one of claims
EP03753632A 2002-07-09 2003-07-07 Method for preparing catalysts for heterogeneous catalysis by multiple-phase impregnation, catalysts and use of said catalysts Withdrawn EP1519789A1 (en)

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Families Citing this family (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2864528B1 (en) * 2003-12-31 2006-12-15 Total France PROCESS FOR TREATING METHANE / CARBON DIOXIDE MIXTURES
US20090264277A1 (en) * 2007-04-17 2009-10-22 Dr. Rishi Raj Picoscale catalysts for hydrogen catalysis
US9173967B1 (en) 2007-05-11 2015-11-03 SDCmaterials, Inc. System for and method of processing soft tissue and skin with fluids using temperature and pressure changes
US8507401B1 (en) 2007-10-15 2013-08-13 SDCmaterials, Inc. Method and system for forming plug and play metal catalysts
EP2204235A1 (en) 2008-12-19 2010-07-07 Total Petrochemicals Research Feluy Catalyst and process for selective hydrogenation of alkynes and dienes
EP2204236A1 (en) 2008-12-19 2010-07-07 Total Petrochemicals Research Feluy Catalyst and process for hydrogenation of hydrocarbon feedstocks
US9126191B2 (en) 2009-12-15 2015-09-08 SDCmaterials, Inc. Advanced catalysts for automotive applications
US8803025B2 (en) 2009-12-15 2014-08-12 SDCmaterials, Inc. Non-plugging D.C. plasma gun
US9149797B2 (en) 2009-12-15 2015-10-06 SDCmaterials, Inc. Catalyst production method and system
US8470112B1 (en) 2009-12-15 2013-06-25 SDCmaterials, Inc. Workflow for novel composite materials
US9039916B1 (en) 2009-12-15 2015-05-26 SDCmaterials, Inc. In situ oxide removal, dispersal and drying for copper copper-oxide
US8545652B1 (en) 2009-12-15 2013-10-01 SDCmaterials, Inc. Impact resistant material
US8557727B2 (en) 2009-12-15 2013-10-15 SDCmaterials, Inc. Method of forming a catalyst with inhibited mobility of nano-active material
US8652992B2 (en) 2009-12-15 2014-02-18 SDCmaterials, Inc. Pinning and affixing nano-active material
US8669202B2 (en) 2011-02-23 2014-03-11 SDCmaterials, Inc. Wet chemical and plasma methods of forming stable PtPd catalysts
AU2012299065B2 (en) 2011-08-19 2015-06-04 SDCmaterials, Inc. Coated substrates for use in catalysis and catalytic converters and methods of coating substrates with washcoat compositions
US9511352B2 (en) 2012-11-21 2016-12-06 SDCmaterials, Inc. Three-way catalytic converter using nanoparticles
US9156025B2 (en) 2012-11-21 2015-10-13 SDCmaterials, Inc. Three-way catalytic converter using nanoparticles
CN104148101B (en) * 2013-05-13 2016-12-28 中国科学院大连化学物理研究所 The method of a kind of methane anaerobic alkene the most processed and catalyst thereof
US10702854B2 (en) 2013-05-13 2020-07-07 Dalian Institute Of Chemical Physics, Chinese Academy Of Sciences Oxygen-free direct conversion of methane and catalysts therefor
WO2014207096A1 (en) 2013-06-27 2014-12-31 Sicat Method for manufacturing shaped beta-sic mesoporous products and products obtained by this method
CN105592921A (en) 2013-07-25 2016-05-18 Sdc材料公司 Washcoats and coated substrates for catalytic converters and method for manufacturing and using same
US9861962B2 (en) 2013-10-08 2018-01-09 Industry Foundation Of Chonnam National University Selective surface impregnation method for catalytically active materials on particulate catalyst support using mutual repulsive force and soblubility difference between hydrophilic solvent and hydrophobic solvent
KR101467292B1 (en) * 2013-10-08 2014-12-01 전남대학교산학협력단 Selective surface impregnation method for catalytic material with the repulsive force between hydrophilic and hydrophobic solvents and catalyst made thereof
US9427732B2 (en) 2013-10-22 2016-08-30 SDCmaterials, Inc. Catalyst design for heavy-duty diesel combustion engines
CN105848756A (en) 2013-10-22 2016-08-10 Sdc材料公司 Compositions of lean NOx trap
US9687811B2 (en) 2014-03-21 2017-06-27 SDCmaterials, Inc. Compositions for passive NOx adsorption (PNA) systems and methods of making and using same
CN111992204B (en) * 2020-09-17 2022-07-19 福建省晋蓝环保科技有限公司 Ozone oxidation catalyst, preparation method and ozone catalytic oxidation device

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2549389A1 (en) * 1983-07-19 1985-01-25 Centre Nat Rech Scient HYDROCARBON HYDROTREATMENT CATALYST, PREPARATION AND APPLICATION THEREOF
US4914080A (en) * 1988-01-27 1990-04-03 Fujitsu Limited Method for fabricating superconductive film
FR2657603B1 (en) * 1990-01-29 1993-07-09 Pechiney Electrometallurgie PROCESS FOR OBTAINING POROUS SOLID BODIES BASED ON REFRACTORY CARBIDE USING ORGANIC COMPOUNDS AND METAL OR METALLOUIDE.
FR2675713B1 (en) * 1991-04-29 1993-07-02 Pechiney Electrometallurgie CATALYTIC SYSTEM, PARTICULARLY FOR THE POSTCOMBUSTION OF EXHAUST GASES AND METHOD FOR MANUFACTURING THE SAME.
FR2684091B1 (en) * 1991-11-21 1994-02-25 Pechiney Recherche METHOD FOR MANUFACTURING METAL CARBIDES WITH A LARGE SPECIFIC SURFACE UNDER ATMOSPHERIC PRESSURE INERATED GAS SCANNING.
FR2704865B1 (en) * 1993-05-06 1995-07-21 Inst Francais Du Petrole Catalytic hydrogenation process.
SA97180048B1 (en) * 1996-05-24 2005-12-21 هوكست سيلانس كوربوريشن HETEROGENEOUS BIMETALLIC VINYL ACETATE FOR THE PRODUCTION OF VINYL ACETATE
FR2769857B1 (en) * 1997-10-16 1999-12-24 Centre Nat Rech Scient CATALYTIC CHEMICAL REACTION PROCESS AND CATALYST
US6472344B1 (en) * 1998-11-18 2002-10-29 Battelle Memorial Institute Catalyst of a metal heteropoly acid salt that is insoluble in a polar solvent on a non-metallic porous support and method of making
WO2000067902A1 (en) * 1999-05-07 2000-11-16 Dsm N.V. Stable catalysts and processes for making and using the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2004007074A1 *

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