WO2022128754A1 - Composition à base d'oxyde de zirconium et d'oxyde de cérium à température maximale de réductibilité réduite, son procédé de production et son utilisation en tant que catalyseur - Google Patents

Composition à base d'oxyde de zirconium et d'oxyde de cérium à température maximale de réductibilité réduite, son procédé de production et son utilisation en tant que catalyseur Download PDF

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WO2022128754A1
WO2022128754A1 PCT/EP2021/085109 EP2021085109W WO2022128754A1 WO 2022128754 A1 WO2022128754 A1 WO 2022128754A1 EP 2021085109 W EP2021085109 W EP 2021085109W WO 2022128754 A1 WO2022128754 A1 WO 2022128754A1
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ions
weight
starting material
ion beam
composition according
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PCT/EP2021/085109
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Lionel Ventelon
Simge DANACI
Alain Demourgues
Mathieu DUTTINE
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Agc Glass Europe
AGC Inc.
Agc Flat Glass North America, Inc.
Agc Vidros Do Brasil Ltda
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Publication of WO2022128754A1 publication Critical patent/WO2022128754A1/fr

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    • 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
    • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/206—Rare earth metals
    • B01D2255/2065—Cerium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20715—Zirconium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/40—Mixed oxides
    • B01D2255/407—Zr-Ce mixed oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases

Definitions

  • the present invention relates to method for increasing the number of free electrons in the lattice of a composition based on zirconium oxide and cerium oxide and the use of the resulting composition in a catalytic system.
  • Ion implantation in compositions for use in catalytic systems has been disclosed for example in W02015015098A1 that describes the ion implantation in a cerium oxide, mixtures of cerium oxide and zirconium oxide for example in Ce0.3Zr0.3O2. Teaches increase of nano-porosity. Better circulation of oxygen and a lowering of the reduction temperature of the composition are reported for an ion implantation dosage between 10 15 and 10 22 ions/g.
  • compositions that may be used for catalytic systems based mainly on cerium and zirconium oxide as main components comprise a certain amount of free electrons in their lattice after ion implantation which depends not only on the dosage of implanted ions, but also on the proportion of zirconium oxide in the composition.
  • compositions may be used in catalytic systems for the treatment of exhaust gases for example, for example of internal combustion engines, such as those used in a variety of transport means.
  • exhaust gases for example, for example of internal combustion engines, such as those used in a variety of transport means.
  • Fig. 1 represents the number of free electrons in a lattice per ion dosage versus the zirconium oxide proportion in compositions according to some embodiments of the present invention.
  • the present invention concerns a composition based on zirconium oxide and cerium oxide with a zirconium oxide proportion of at least 15% by weight and a cerium oxide proportion of at least 25% by weight, characterized in that it comprises between 3.0 x 1 o 14 and 9 x 1 o 16 free electrons per gram in the compositions lattice.
  • compositions of the present invention may further comprise at least 0.5% by weight, expressed as the oxide, of at least one dopant element, chosen from lanthanides other than cerium and from yttrium.
  • lanthanides is understood to mean elements of the group formed by the elements of the Period Table with an atomic number lying between 57 and 71 included.
  • composition of the present invention may further comprise a precious metal chosen from platinum, palladium and rhodium.
  • compositions of the invention are obtained by implanting the starting material of mixed cerium zirconium oxide, optionally comprising a dopant, optionally comprising a precious metal as described herein.
  • compositions of the present invention are implanted with ions of nitrogen, argon or oxygen, resulting in the creation of free electrons in the composition’s lattice.
  • compositions of the invention are of the mixed oxide type, based on zirconium oxide and cerium oxide as main components. They may also include at least one dopant element chosen from lanthanides other than cerium and from Group III elements. In this case, the compositions may therefore be in particular ternary or quaternary compositions.
  • the aforementioned at least one dopant element may more particularly be chosen from lanthanum, neodymium, praseodymium, gadolinium, yttrium and scandium.
  • the compositions may more particularly comprise oxides of zirconium, cerium, yttrium and lanthanum or of zirconium, cerium, and yttrium.
  • the contents of the various constituents in the compositions of the invention may vary. These contents are expressed here, and for the rest of the description, as mass percentage of the constituent’s oxide (ZrO2, CeO2 and TR2O3, TR denoting the dopant, yttrium and/or a lanthanide other than cerium) relative to the overall composition.
  • the zirconium content is at least 15%, and may particularly be at least 25%, even more particularly at least 28%, and even more particularly at least 30%. Furthermore, the zirconium content may be at most 55%, more particularly be at most 50% and even more particularly at most 35%.
  • the cerium content is at least 25%, and may more particularly be at least 30% and even more particularly at least 35%.
  • the cerium content may be at most 65%, more particularly at most 62% and even more particularly at most 55%.
  • the content of a dopant is at least 0.5% by weight, expressed as the oxide.
  • the content of a dopant may be most 15% and it may be more particularly at most 10%, and it may be between 3% and 10%.
  • compositions of the invention optionally further comprise precious metals.
  • the nature of these metals and the techniques of incorporating them into these compositions are well known to those skilled in the art.
  • the metals may be platinum, rhodium, palladium or iridium, and they may especially be incorporated into the compositions by impregnation.
  • Other methods are also known in the art for preparing metal comprising catalyst compositions, such as coprecipitation, impregnation-precipitation, sol-gel deposition, physical vapor deposition, chemical vapor deposition, atomic layer deposition, electroplating, underpotential deposition, cementation, transmetalation, and flame spray pyrolysis.
  • compositions of the invention are characterized by the fact that they have free electrons trapped in the lattice, in particular due to the implantation of ions.
  • Electron paramagnetic resonance spectroscopy (EPR) is used to determine the number free electrons trapped in the lattice.
  • Electron paramagnetic resonance spectroscopy (EPR) is also called Electron Spin Resonance Spectroscopy (ESR) and is a well-known method for studying unpaired electrons in any materials.
  • compositions of the present invention may be provided with between 3 x 10 14 and 9 x i o 16 free electrons per gram in the compositions’ lattice.
  • compositions comprise at least 5 x i o 14 advantageously at least 6 x 10 14 , more advantageously at least 7 x 10 14 free electrons per gram in the compositions’ lattice.
  • compositions comprise at most 8 x 1 O 16 advantageously at least 7 x 1 O 1S , more advantageously at least 6 x 10 16 free electrons per gram in the compositions’ lattice.
  • the preparation of the starting material for the compositions of the present invention is well known. Generally it comprises the following steps: a. a mixture comprising a zirconium compound, a cerium compound and, optionally a compound of an aforementioned dopant element is formed; b. said mixture is brought into contact with a basic compound, by means of which a precipitate is obtained; c. said precipitate is separated and then calcined, forming a calcined precipitate; d. optionally, a precious metal is incorporated into the calcined precipitate; e.
  • the starting material generally obtained as a powder, prepared according to steps (a) to (d) are the implanted with ions of nitrogen, argon or oxygen.
  • the step (a) of the method therefore consists in preparing a mixture in a liquid medium of a zirconium compound, a cerium compound and optionally at least one compound of the additional aforementioned element.
  • the mixing is generally carried out in a liquid medium, which is preferably water.
  • the compounds are preferably soluble compounds. These may especially be zirconium, cerium, lanthanide, and yttrium salts. These compounds may be chosen from nitrates, sulphates, acetates, chlorides and ceric ammonium nitrates.
  • zirconium sulphate zirconyl nitrate or zirconyl chloride.
  • zirconyl nitrate is used.
  • cerium (IV) salts such as, for example, nitrates or ceric ammonium nitrates, which are particularly suitable here.
  • Ceric nitrate may be used. It is advantageous to use salts with a purity of at least 99.5% and more particularly at least 99.9%.
  • An aqueous ceric nitrate solution may for example be obtained by the reaction of nitric acid on a hydrated ceric oxide prepared conventionally by reacting a solution of a cerous salt, for example cerous nitrate, with an ammonia solution in the presence of hydrogen peroxide. It is also possible in particular to use a ceric nitrate solution obtained by the method of electrolytic oxidation of a cerous nitrate solution, as described in the document FR-A-2 570 087, which constitutes here an advantageous raw material.
  • the aqueous solutions of cerium salts and zirconyl salts may have a certain initial free acidity, which can be adjusted by the addition of a base or an acid.
  • an initial solution of cerium and zirconium salts having actually a certain free acidity as mentioned above and solutions that will have been neutralized beforehand to a greater or lesser extent.
  • This neutralization may be carried out by the addition of a basic compound to the aforementioned mixture so as to limit this acidity.
  • This basic compound may for example be an ammonia solution or a solution of alkali metal (sodium, potassium, etc.) hydroxides, but preferably an ammonia solution.
  • the starting mixture contains a cerium compound in which cerium is in the Ce(lll) form
  • an oxidizing agent for example hydrogen peroxide.
  • This oxidizing agent may be used by being added to the reaction mixture during step (a) or during step (b), especially at the end of the latter step.
  • sol denotes any system consisting of fine solid particles of colloidal dimensions, that is to say dimensions of between about 1 nm and about 500 nm, based on a zirconium or cerium compound, this compound generally being a zirconium or cerium oxide and/or hydrated oxide, in suspension in an aqueous liquid phase, said particles furthermore optionally being able to contain residual amounts of bonded or adsorbed ions, such as for example nitrate, acetate, chloride or ammonium ions.
  • the zirconium or cerium may be either completely in the form of colloids, or simultaneously in the form of ions and in the form of colloids.
  • step (b) of the method said mixture is brought into contact with a basic compound.
  • base or basic compound it is possible to use products of the hydroxide type. Mention may be made of alkali metal or alkaline-earth metal hydroxides. It is also possible to use secondary, tertiary or quaternary amines. However, amines and aqueous ammonia may be preferred in so far as they reduce the risks of contamination by alkali metal or alkaline-earth metal cations. Mention may also be made of urea.
  • the basic compound is generally used in the form of an aqueous solution.
  • the way in which the mixture and the solution are brought into contact with each other is not critical. However, this contacting may be carried out by introducing the mixture into the solution of the basic compound. This variant is preferable in order to obtain compositions in the form of solid solutions.
  • the contacting or the reaction between the mixture and the solution, especially the addition of the mixture into the solution of the basic compound, may be carried out in a single step, gradually or continuously, and it is preferably performed with stirring. It is preferably carried out at room temperature.
  • the product obtained may optionally be dried, by methods well known o the person skilled in the art., before the calcination step. Drying may be performed for example in an oven at a temperature of 100°C for more than 6 hours, for example up to 12 hours.
  • Step (c) of the process is a calcination step.
  • the calcination takes place in an oxidizing atmosphere, for example in air.
  • the calcination is generally carried out at a temperature of between 300 and 1000° C. for a time of generally at least 30 minutes.
  • the calcination is carried out at a temperature of between 300 and 600°C, more advantageously between 400 and 500°C, even more advantageously between 450 and 550°C.
  • the calcination is carried out for a duration of between 2 to 4 hours.
  • a precious metal chosen from platinum, rhodium, palladium or iridium is incorporated into the composition, for example by impregnation or magnetron sputtering.
  • the compositions of the invention may be employed in combination with precious metals.
  • precious metals The nature of these metals and the techniques of incorporating them into these compositions are well known to those skilled in the art.
  • the metals may be platinum, rhodium, palladium or iridium, and they may especially be incorporated into the compositions by impregnation or magnetron sputtering.
  • the starting material of resulting of steps (a) to (d) is implanted with ions selected among the ions of nitrogen, argon, and oxygen.
  • the ion implantation creates free electrons in the lattice of the material that improve the efficiency of the catalytic process and in particular reduce the reducibility temperatures of surface Ce(IV) and bulk Ce(IV) species.
  • the number of free electrons in the lattice depends on the composition of the starting material, in particular of the relative amounts of cerium oxide, zirconium oxide and of the amount and type of dopant(s). It was in particular found that the defect creation efficiency, that is the amount of free electrons created in the lattice per implanted ion, depends on the composition of the starting material.
  • the present invention thus further concerns the use of implanted ions to increase the number of free electrons in the lattice of cerium and zirconium oxide based starting material compositions.
  • This ion implantation step comprises providing an ion beam, implanting the starting material with an ion beam dose per weight of starting material, comprised between 4.2 x 18 ions/g and 4.5 x 10 19 ions/g comprising monocharged and multicharged ions with an energy of the monocharged ions in the ion beam from at least 10 keV to at most 100 keV;
  • the ion beam is generated by a plasma filament ion beam source or an electron cyclotron resonance (ECR) plasma source, such as an ECR Plasma Immersion ion implantation (PHI) or preferably an ECR plasma confined with permanent magnets.
  • ECR electron cyclotron resonance
  • PHI ECR Plasma Immersion ion implantation
  • PHI ECR plasma confined with permanent magnets.
  • the catalyst starting material is provided on a support and is mixed intermittently or continuously, so as to uniformly distribute the implanted ions in the catalyst starting material.
  • a carrier or support is used that provides continuous mixed during implantation for example a vibrating plate or bowl, a rotary bowl or a rotary drum.
  • the carrier combines rotating and vibrating movements. It has been observed that the resulting implanted catalyst material is more homogeneously implanted when continuous mixing is provided, such as for example in a rotary bowl or drum.
  • the catalyst starting material on the support shall advantageously form a layer of catalyst starting material having a thickness that is larger than the implantation depth of the ions in the catalyst starting material to avoid implanting ions in the support.
  • At least part of the ions are derived from argon atoms, oxygen atoms and/or nitrogen atoms.
  • At least part of the ions, preferably all ions, are derived from nitrogen atoms.
  • At least 50% of the ions preferably at least 75% of the ions, more preferably at least 90% of the ions, even more preferably at least 95% of the ions and most preferably 100% of the ions are derived from nitrogen atoms.
  • At least part of the ions are derived from argon atoms.
  • At least 50% of the ions preferably at least 75% of the ions, more preferably at least 90% of the ions, even more preferably at least 95% of the ions and most preferably 100% of the ions are derived from argon atoms.
  • the energy E of the monocharged ions in the ion beam is at least 10 keV, preferably at least 20 keV, more preferably at least 30 keV, even more preferably at least 40 keV and most preferably at least 50 keV.
  • the energy E of the monocharged ions in the ion beam is at most 100 keV, preferably at most 90 keV, more preferably at most 80 keV, even more preferably at most 70 keV and most preferably at most 60 keV.
  • the energy E of the monocharged ions in the ion beam is at least 10 keV to at most 100 keV, preferably at least 20 keV to at most 90 keV, more preferably at least 30 keV to at most 80 keV, even more preferably at least 40 keV to at most 70 keV and most preferably at least 50 keV to at most 60 keV.
  • the ion beam comprises a mixture of differently charged ions, and therefore each differently charged ion may have a different energy. This is the result that the energy of the ions in the ion beam is the results of being accelerated by a voltage, preferably the extraction voltage.
  • a nitrogen ion beam may comprise 58% N + ; 32%N 2+; 9%N 3+ and 1 %N +4 .
  • the ion beam is made up of 58% of nitrogen ions with an energy of 40 keV, 32% of nitrogen ions with an energy of 80 keV, 9% of nitrogen ions with an energy of 120 keV and 1 % of nitrogen ions with an energy of 160 keV.
  • the ion beam has an average charge (g avr ) of at least 1.00 to at most 5.00, preferably at least 1.10 to at most 3.00, more preferably at least 1 .20 to at most 2.00, even more preferably at least 1 .30 to at most 1 .75 yet even more preferably at least 1 .40 to at most 1 .60 and most preferably at least 1 .50 to at most 1 .55.
  • g a vr is the sum of all the charges in the ion beam divided by the number of ions in the ion beam.
  • the monocharged ions in the ion beam have an average energy (E avr ) of least 10 keV to at most 100 keV, preferably at least 20 keV to at most 90 keV, more preferably at least 30 keV to at most 80 keV, even more preferably at least 40 keV to at most 70 keV and most preferably at least 50 keV to at most 60 keV.
  • E av r is the sum of all the energy values in the ion beam divided by the number of ions in the ion beam. Therefore, an ion beam with an g av r of 1 .53 which is extracted by an extraction voltage of 40 kV has an E a vr of 61 .2 keV.
  • the ions with the highest energy in the ion beam have an energy of at most 200 keV. In some embodiments, the ions with the lowest energy in the ion beam have an energy of at least 10 keV.
  • the ion beam is generated by an ECR plasma confined with permanent magnets.
  • the ion beam source comprises a mono- and multicharged ions plasma confined with permanent magnets which is generated by electron cyclotron resonance (ECR) using a high frequency, such as 2.45; 7.50 or 10.00 GHz.
  • ECR electron cyclotron resonance
  • a monocharged ion is an ion bearing a single positive charge
  • a multicharged ion is an ion bearing more than one positive charge.
  • the ion beam is then extracted to generate mono-multi-energies ions beam penetrating more deeply in the catalytic starting material.
  • This kind of ion beam is more efficient to treat nanoparticles or catalytic material inside other material, such as support, or other catalytic material.
  • the ions penetrate deeper in the catalytic material than when the implantation is made with only monocharged ions. It is in particular believed, that the deeper penetration of multicharged ions enables the generation of a larger amount of free electrons than what is obtained with monocharged ions only. Possibly this is also due to the fact that the implanted ions are distributed over a larger depth in the material. Unpaired electrons initially generated have a lesser probability of recombination than when the implanted ions are all concentrated at a lower depth in the material.
  • Plasma filament ion beam sources and ECR Plasma Immersion ion implantation (PHI) sources generate molecular ions with lower charges states, in particular only monocharged ions or molecular ions, which have the drawbacks to be heavier with less energy, in others words to have reduced depth ranges to treat nanoparticles or catalyst.
  • the ion beam dose is at least 10 13 ions/cm 2 , preferably at least 10 14 ions/cm 2 , even more preferably at least 10 15 ions/cm 2 at the point of contact with the catalyst starting material, where the catalyst starting material is considered to be forming an essentially flat surface
  • the ion beam dose is at most 10 18 ions/cm 2 , preferably at most 10 17 ions/cm 2 , even more preferably at most 10 16 ions/cm 2 at the point of contact with the catalyst starting material, where the catalyst starting material is considered to be forming an essentially flat surface.
  • the ion beam dose is at least 10 13 ions/cm 2 to at most 10 18 ions/cm 2 , preferably at least 10 14 ions/cm 2 to at most 10 17 ions/cm 2 , even more preferably at least 10 15 ions/cm 2 to at most 10 16 ions/cm 2 at the point of contact with the catalyst starting material, where the catalyst starting material is considered to be forming an essentially flat surface.
  • the total ion beam dose is split into m separate doses, and wherein the catalytic starting material is mixed or stirred each time between the m different ion implantation treatments, preferably m is at least 4 to at most 64, more preferably at least 8 to at most 32, even more preferably at least 12 to at most 24 and most preferably at least 16 to at most 18.
  • An amount of powder may be spread over a given area or surface and exposed to the ion beam m times to obtain a total ion dose.
  • the powder may be mixed and may be spread again over the original area to allows to obtain a homogeneous treatment for the powder starting material.
  • m is at least equal to the ratio of the mean thickness of the powder spread over a given area and the mean free path of the ions inside the powder. The free path being the path ions travel inside the powder before they are stopped by the powder.
  • the advancement step of the ion beam is at least 1 % to at most 50%, preferably at least 2% to at most 40%, more preferably at least 5% to at most 30%, even more preferably at least 7% to at most 20% and most preferably at least 10% to at most 15%.
  • the ion beam may move in a series of round trips separated by a distance corresponding to a fraction of the ion beam diameter called advancement step.
  • a step of 10% for a beam with a diameter of 22.5 mm, means that for each round trip a shift of 2.25 mm is performed.
  • the advancement step may result in a high surface homogeneity of the treatment, preferably regardless the intensity distribution of the ion beam, which may be for instance be a Gaussian shape with more intensity at the centre and less intensity at the periphery.
  • the method comprises n different implanting steps with n multiple doses Xj, preferably wherein each dose Xj is X/n, X being the total ion beam dose, i.e. the sum of the n doses Xj.
  • the different implanting steps differ by at least one implantation parameter, e.g. different ions may be used in different steps.
  • n is at most 3, more preferably n is at most 2, and most preferably n is 1 .
  • the method comprises implanting the catalyst starting material with an ion beam that is performed at a pressure of at most 10 -4 Torr, preferably at most 10' 5 Torr, more preferably at most 10' 6 Torr and most preferably at most 10' 7 Torr.
  • noble gas such as Ar, Kr or Xe
  • lower vacuum levels such as lower than 10' 4 Torr, preferably lower than 10' 5 Torr, more preferably lower than 10 -B Torr and most preferably lower than 10' 7 Torr.
  • the pressure in the treatment chamber is at least 3 x 10' 6 Torr, preferably at least 5x1 O' 6 Torr more preferably at least 7 x 10' 6 Torr, even more preferably at least 10x1 O' 6 Torr and most preferably at least 20x1 O' 6 Torr.
  • These vacuum levels help to at least partially neutralize electrostatic barrier induced by the implanted ions.
  • the catalyst starting material is provided on a carrier or support comprising means for dissipating an static charges.
  • the support may comprise or consist of an electrically conducting material, such as a metal, and be electrically grounded.
  • the ion implantation dose is usually expressed using the unit ions/cm 2 .
  • This dosage may be calculated using the following formula (units omitted): wherein D is the dosage [ions/cm 2 ], I is the ion beam current [A], t is the implantation time [s], S is the surface area [cm 2 ], q is the elementary charge 1.6x10 19 [Coulomb], This formula is easily adapted for mixtures of single charge and multicharge ions.
  • the ion dose is conveniently expressed using the unit ions/g.
  • This dosage may be calculated using the following formula (units omitted): wherein, with the units in square brackets, D is the dosage [ions/cm 2 ], I is the ion beam current [A], t is the implantation time [s], Q is the quantity of implanted catalyst starting material [g], q is the elementary charge 1.6x10 -19 [Coulomb], This formula is easily adapted for mixtures of single charge and multicharge ions.
  • this dosage can be derived from the dosage expressed in ions/cm 2 and the surface density ⁇ J , in g/cm 2 , of the evenly distributed catalyst starting material as follows:
  • compositions that are the result of any possible combination of the embodiments hereinabove.
  • compositions of the invention are in the form of powders, but they may optionally be formed into granules, beads, cylinders or honeycombs of varying dimensions. These compositions may be applied to any support normally used in the catalysis field, that is to say, in particular, thermally inert supports. This support may be chosen from alumina, titanium oxide, cerium oxide, zirconium oxide, silica, spinels, zeolites, silicates, crystalline silicon aluminum phosphates and crystalline aluminum phosphates.
  • compositions may also be used in catalytic systems.
  • These catalytic systems may include a wash coat having catalytic properties and based on these compositions, on a substrate for example of the metal or ceramic monolith type.
  • the wash coat may itself include a support of the type of those mentioned above. This wash coat is obtained by mixing the composition with the support so as to form a suspension that may then be deposited on the substrate.
  • catalytic systems and more particularly the compositions of the invention, may have very numerous applications. They are thus particularly well suited to, and therefore usable in, the catalysis of various reactions such as, for example, dehydration, hydrosulfurization, hydrodenitrification, desulfurization, hydrodesulfurization, dehydrohalogenation, reforming, steam reforming, cracking, hydrocracking, hydrogenation, dehydrogenation, isomerization, dismutation, oxychlorination and dehydrocyclization of hydrocarbons or other organic compounds, oxidation and/or reduction reactions, the Claus reaction, the treatment of internal combustion exhaust gases, demetalization, methanation, shift conversion, catalytic oxidation of soot emitted by internal combustion engines, such as diesel or petrol engines operating in lean mode. Finally, the catalytic systems and the compositions of the invention may be used as NOx traps.
  • the invention also relates to the use of a composition or of a catalytic system such as those described above for the manufacture of a catalyst for automobile postcombustion.
  • Item 1 Composition based on zirconium oxide and cerium oxide comprising a zirconium oxide proportion of at least 15% by weight and a cerium oxide proportion of at least 25% by weight, characterized in that it comprises between 3.0 x 10 14 and 9 x 16 free electrons per gram in the compositions’ lattice.
  • Item 2 Composition according to Item 1 , characterized in that it comprises at least 0.5 weight % expressed as the oxide of at least one dopant element chosen from lanthanum, neodymium, praseodymium, and yttrium.
  • Item 3 Composition according to any one of the preceding items, characterized in that it comprises a zirconium oxide proportion of at least 25% by weight, particularly at least 28% by weight, more particularly at least 30% by weight.
  • composition according to any one of the preceding items characterized that it comprisesat least 5 x 1 o 14 , advantageously at least 6 x 10 14 , more advantageously at least 7 x 10 14 free electrons per gram in the compositions’ lattice.
  • composition according to any one of the preceding items, characterized in that it comprises a cerium oxide proportion by weight of at most 65%, particularly at most 62% and even more particularly at most 55%.
  • composition according any one preceding item characterized in that it comprises no precious metal.
  • Item 7 Composition according to any one of items 1 to 6, characterized in that it further comprises a precious metal chosen from platinum, palladium and rhodium.
  • Item 8 Composition according to any one of the preceding items, characterized in that it comprises a cerium oxide proportion by weight of at most 65%, particularly at most 62% and even more particularly at most 55%.
  • Item 9 Method of preparing a composition according to one of the preceding items, characterized in that it comprises the following steps: a. providing a starting material based on zirconium oxide and cerium oxide comprising a zirconium oxide proportion of at least 15% by weight and a cerium oxide proportion of at least 25% by weight, optionally further comprising at least one dopant element chosen from lanthanides other than cerium and from yttrium and optionally further comprising a precious metal chosen from platinum, palladium and rhodium. b. providing an ion beam, c.
  • implanting the starting material with an ion beam dose comprised between 4.2 x Q 18 ions/g and 4.5 x 0 19 ions/g comprising monocharged and multicharged ions with an energy of the monocharged ions in the ion beam from at least 10 keV to at most 100 keV.
  • Item 10 Method according to item 9 characterized in that the starting material comprises at least 0.5 weight % expressed as the oxide of at least one dopant element chosen from lanthanum, neodymium, praseodymium, and yttrium.
  • Item 11 Method according to any one of items 9 to 10 characterized in that the starting material comprises a zirconium oxide proportion of at least 25% by weight, particularly at least 28% by weight, more particularly at least 30% by weight.
  • Item 12 Method according to any one of items 9 to 11 characterized in that the starting material comprises comprises a cerium oxide proportion by weight of at most 65%, particularly at most 62% and even more particularly at most 55%.
  • Item 13 Method according to any one of items 9 to 12 characterized in that the starting material comprises no precious metal.
  • Item 14 Method according to any one of items 9 to 12 characterized in that the starting material further comprises a precious metal chosen from platinum, palladium and rhodium.
  • Item 15 Method according to any one of items 9 to 14 characterized in that the starting material comprises a cerium oxide proportion by weight of at most 65%, particularly at most 62% and even more particularly at most 55%.
  • Item 16 Method according to any one of items 9 to 15, wherein the ion beam is generated by a plasma source selected from a. a plasma filament ion beam source or b. an electron cyclotron resonance plasma source, selected among c. a ECR Plasma Immersion ion implanter or d. an electron cyclotron resonance plasma confined with permanent magnets.
  • a plasma source selected from a. a plasma filament ion beam source or b. an electron cyclotron resonance plasma source, selected among c. a ECR Plasma Immersion ion implanter or d. an electron cyclotron resonance plasma confined with permanent magnets.
  • Item 17 Method according to any one of items 9 to 16, wherein at least part of the ions or all ions, are derived from argon atoms, oxygen atoms and/or nitrogen atoms.
  • Item 18 Method according to any one of items 9 to 17, characterized in that the starting material further comprises a precious metal chosen from platinum, palladium and rhodium.
  • Catalytic system characterized in that it comprises a composition according to one of Items 1 to 8.
  • Item 20 Method of treating the exhaust gases of internal combustion engines, characterized in that a catalytic system according to item 19 or in that a composition according to one of Items 1 to 8 is used as catalyst.
  • the implantation step is performed in the following way.
  • the starting material from 0.5 to 16g, is placed in a microimplantor designed by the company Ionics, including an ECR (Electron Cyclotron Resonance) ion source powered by a 10 GHz and 50 W HF amplifier, and an ion extraction system of 10 kV (kiloVolt).
  • ECR Electro Cyclotron Resonance
  • the plasma of the ion source is confined by permanent magnets allowing the production of monocharged and multicharged ions).
  • the starting material particles agglomerated in powder form, are provided in a vibrating bowl, centered below the ion beam. The diameter of the powder at its surface is slightly larger than the diameter of the diameter of the ion beam.
  • the pressure in the treatment chamber is kept at 10' 5 mbar.
  • the treatment is done with a mixture of mono and multicharged nitrogen ions, in the case of nitrogen ions for example 58% N + 32%, N 2+ , 9% N 3+ , and 1 % N 4+ , extracted by an extraction voltage of for example 35 kV.
  • the mean charge state is 1 .53 and the mean energy E avr equals 53 keV at the extraction voltage above.
  • the total dose can be implanted uniformly, without interruption, while the bowl was kept vibrating.
  • the ratio of free electrons over implanted ions dosage N/D depends on the starting material composition, expressed here as the weight percentage of zirconium oxide in the starting material composition ZrO2%.
  • the lower curve ( ⁇ - ⁇ ) indicates the trend observed for a dose of 4.49 x 10 18 ions/g.
  • the middle curve ( - ) indicates the trend observed for a dose of 4.00 x 1019 ions/g.
  • the upper curve ( - ) indicates the trend observed for a dose of 4.49 x 19 ions/g.
  • the efficiency for generating free electrons in the lattice of a composition with a given dosage of ions depends on the proportions of the constituents in the starting material composition.

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Abstract

La présente invention concerne une composition à base d'oxyde de zirconium et d'oxyde de cérium comprenant une proportion d'oxyde de zirconium d'au moins 15 % en poids et une proportion d'oxyde de cérium d'au moins 25 % en poids, caractérisée en ce qu'elle comprend entre 3,0 × 1 014 et 9 × 1 016 électrons libres par gramme dans le réseau de compositions et son procédé de fabrication. La présente invention concerne en outre un système catalytique et un procédé de traitement des gaz d'échappement de moteurs à combustion interne utilisant la composition ci-dessus.
PCT/EP2021/085109 2020-12-17 2021-12-09 Composition à base d'oxyde de zirconium et d'oxyde de cérium à température maximale de réductibilité réduite, son procédé de production et son utilisation en tant que catalyseur WO2022128754A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2570087A1 (fr) 1984-09-13 1986-03-14 Rhone Poulenc Spec Chim Procede d'oxydation electrolytique et ensemble d'electrolyse pour sa mise en oeuvre
US20130052108A1 (en) * 2010-01-11 2013-02-28 Rhodia Operations Composition containing oxides of zirconium, cerium and another rare earth having reduced maximum reducibility temperature, a process for preparation and use thereof in the field of catalysis
WO2015015098A1 (fr) 2013-08-01 2015-02-05 Quertech Procédé de traitement par un faisceau d'ions de poudre a base d'oxyde de cerium
WO2019238701A1 (fr) * 2018-06-12 2019-12-19 Agc Glass Europe Procédé de préparation de nanoparticules catalytiques, de surfaces catalytiques et/ou de catalyseurs

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2570087A1 (fr) 1984-09-13 1986-03-14 Rhone Poulenc Spec Chim Procede d'oxydation electrolytique et ensemble d'electrolyse pour sa mise en oeuvre
US20130052108A1 (en) * 2010-01-11 2013-02-28 Rhodia Operations Composition containing oxides of zirconium, cerium and another rare earth having reduced maximum reducibility temperature, a process for preparation and use thereof in the field of catalysis
WO2015015098A1 (fr) 2013-08-01 2015-02-05 Quertech Procédé de traitement par un faisceau d'ions de poudre a base d'oxyde de cerium
WO2019238701A1 (fr) * 2018-06-12 2019-12-19 Agc Glass Europe Procédé de préparation de nanoparticules catalytiques, de surfaces catalytiques et/ou de catalyseurs

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
NANCY ARTIOLI ET AL: "Ion beam surface engineering for highly active nanocatalysts OW-403-1", CONFERENCE PROCEEDINGS ARTICLE, 17 June 2015 (2015-06-17), NAM, Pittsburg, USA, XP055524968 *

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