WO1996011740A1 - Nitrogen oxide reducing catalyst compositions based on tantalum, vanadium, niobium, copper or antimony - Google Patents

Nitrogen oxide reducing catalyst compositions based on tantalum, vanadium, niobium, copper or antimony Download PDF

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Publication number
WO1996011740A1
WO1996011740A1 PCT/FR1995/001302 FR9501302W WO9611740A1 WO 1996011740 A1 WO1996011740 A1 WO 1996011740A1 FR 9501302 W FR9501302 W FR 9501302W WO 9611740 A1 WO9611740 A1 WO 9611740A1
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WO
WIPO (PCT)
Prior art keywords
group
niobium
catalytic
antimony
copper
Prior art date
Application number
PCT/FR1995/001302
Other languages
French (fr)
Inventor
Philippe Barthe
Pierre Macaudiere
Thierry Seguelong
Original Assignee
Rhone-Poulenc Chimie
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from FR9412200A external-priority patent/FR2725638A1/en
Priority claimed from FR9414511A external-priority patent/FR2727636A1/en
Application filed by Rhone-Poulenc Chimie filed Critical Rhone-Poulenc Chimie
Priority to AU36567/95A priority Critical patent/AU700120B2/en
Priority to MX9702654A priority patent/MX9702654A/en
Priority to BR9509354A priority patent/BR9509354A/en
Priority to JP8512976A priority patent/JPH10502020A/en
Priority to KR1019970702403A priority patent/KR970706888A/en
Priority to EP95934177A priority patent/EP0785820A1/en
Publication of WO1996011740A1 publication Critical patent/WO1996011740A1/en
Priority to FI971497A priority patent/FI971497A/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/847—Vanadium, niobium or tantalum or polonium
    • 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
    • B01D53/92—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
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
    • 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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/18—Arsenic, antimony or bismuth
    • 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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/20—Vanadium, niobium or tantalum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/208—Hydrocarbons
    • 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
    • B01D2255/20723—Vanadium
    • 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
    • B01D2255/20761—Copper
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)

Definitions

  • the present invention relates to catalytic compositions based on tantalum, vanadium, niobium, copper or antimony for the reduction of emissions of nitrogen oxides (NO x ) in the treatment of a gas.
  • NO x nitrogen oxides
  • the object of the invention is therefore to provide a catalytic composition having an effect for the reduction of NOx.
  • the catalytic composition according to a first embodiment of the invention for the reduction of emissions of nitrogen oxides in the treatment of a gas with a high oxygen content is characterized in that it is based on '' at least one element chosen from the group comprising tantalum, vanadium, niobium and antimony.
  • the catalytic composition is characterized in that it is based on at least one element chosen from a first group comprising tantalum, vanadium, niobium and antimony and d '' at least one other element chosen from a second group comprising copper, silver and gold.
  • the catalytic composition is characterized in that it is based on at least one element chosen from a first group comprising tantalum, vanadium, niobium, antimony and copper, and at least at least one other element chosen from a second group comprising zinc and the elements of groups IIIb, IVb and Vb of the periodic table.
  • the catalytic composition is characterized in that it comprises copper and at least one other element chosen from the group Via of the periodic table.
  • compositions of the invention have an action in reducing the emissions of nitrogen oxides either in the treatment of gases or in the presence or in the absence of a hydrocarbon and / or an organic compound containing oxygen. In some cases, these compositions are effective at low temperatures.
  • the catalytic composition comprises at least one element chosen from tantalum, vanadium, niobium and antimony.
  • the catalytic composition comprises two categories of elements. It in fact comprises at least one element chosen from a first group consisting of tantalum, vanadium, niobium and antimony. It also comprises a second element chosen from a second group consisting of copper, silver and gold.
  • the catalytic composition also comprises two categories of elements. It first comprises at least one element chosen from a first group consisting of tantalum, vanadium, niobium, antimony and copper, and at least one other element chosen from a second group comprising zinc and the elements of groups Illb, IVb and Vb of the periodic table.
  • group IIIb use will be made more particularly of gallium and indium.
  • group IVb mention will be made of tin in particular and antimony and bismuth for group Vb.
  • compositions according to the second embodiment and those of the third embodiment based on tantalum, vanadium, niobium and antimony have the advantage of being effective at low temperature.
  • the composition comprises copper and at least one other element chosen from the Via group of the periodic table.
  • compositions of the invention can also comprise a support.
  • any support usually used in the field of catalysis can be used, such as, for example, ZrO 2 , AI 2 O 3 , TiO 2 or SiO 2 .
  • lanthanide oxides such as CeO 2
  • these supports possibly being doped, or alternatively spinel type oxides, zeolites, silicates, crystalline silicoaluminum phosphates, crystalline aluminum phosphates, these silicates or phosphates which can comprise metal substituents such as titanium, iron, magnesium, zinc, manganese, cobalt, gallium, lanthanum, copper, molybdenum, chromium, germanium or boron.
  • cerium oxide can be used as a support.
  • alumina resulting from the rapid dehydration of at least one aluminum hydroxide such as bayerite, hydrargillite or gibbsite, nordstrandite and / or at least one aluminum oxyhydroxide such as boehmite, pseudoboehmite and diaspore.
  • aluminum hydroxide such as bayerite, hydrargillite or gibbsite, nordstrandite and / or at least one aluminum oxyhydroxide such as boehmite, pseudoboehmite and diaspore.
  • a stabilized alumina As stabilizing element, mention may be made of rare earths, barium, silicon and zirconium. As rare earth there may be mentioned very particularly lanthanum or the neodymium lanthanum mixture.
  • titanium oxide it is also possible to use an oxide stabilized for example by a rare earth such as lanthanum, barium, strontium, phosphorus, silicon, zirconium or aluminum.
  • a rare earth such as lanthanum, barium, strontium, phosphorus, silicon, zirconium or aluminum.
  • the elements described above and constituting the composition may be present in the latter under different types of phases generally in the form of oxides or mixed oxides, these mixed oxides possibly containing certain elements of the support in the case of the supported compositions .
  • compositions of the invention can vary within wide proportions.
  • the invention therefore applies to compositions in which tantalum, vanadium, niobium, antimony and copper are in the majority in atomic percentage relative to the other elements such as those where these other elements are in the majority.
  • this amount is generally between 1 and 50% and more particularly, in particular in the case of copper, between 10 and 50%, expressed in atomic content of element relative to the sum of atoms of support elements and moles.
  • compositions of the invention can finally comprise precious metals of the type conventionally used in catalysis and in particular in catalysis of automobile afterburning.
  • compositions which comprise copper and at least one other element chosen from the groups Va, IIIb, IVb and Vb of the periodic table and a cerium oxide support.
  • compositions essentially comprising the elements mentioned above that is to say the compositions in which it is these only elements which have a catalytic action, optionally in combination with precious metals of the type described. above.
  • the catalytic compositions of the invention can be prepared by any process which makes it possible to obtain an intimate mixture of the constituents of the compositions of the invention. Various methods can be mentioned by way of example.
  • these compositions are obtained by chamotte of precursors of the elements and, where appropriate, of the support.
  • These precursors are generally oxides, hydroxides, carbonates or oxalates. They are mixed and ground then optionally shaped under pressure, for example pellets. The mixture is then calcined.
  • a solution or a slip of salts of the elements and, where appropriate, of the support is first formed.
  • salts one can choose the salts of inorganic acids such as nitrates, sulfates or chlorides.
  • salts of organic acids and in particular the salts of saturated aiiphatic carboxylic acids or the salts of hydroxycarboxylic acids.
  • either the solution or the slip is precipitated by adding a precipitating agent in the presence, if necessary, of the support, or it is atomized before calcination.
  • a soil can be used instead of a salt of the elements.
  • the process is carried out by impregnating the support with a solution or a soil of the abovementioned elements. After impregnation, the support is optionally dried and then it is calcined.
  • the solutions that can be used are the same as those described above.
  • alcoholic solutions of these elements are more generally used, in particular solutions of chlorides.
  • compositions according to the second or third embodiment of the invention For the preparation by impregnation of a composition according to the second or third embodiment of the invention, it is possible either to co-impregnate the elements of the different groups, or to proceed in two stages.
  • the support is first impregnated with a solution of one of the two groups of elements.
  • the support is optionally dried.
  • the support is impregnated with a solution of an element from the other group.
  • drying and calcining the support thus impregnated.
  • Dry impregnation consists in adding to the product to be impregnated a volume of an aqueous solution of the element which is equal to the pore volume of the solid to be impregnated.
  • compositions of the invention can be in various forms such as granules, balls, cylinders or honeycomb of variable dimensions.
  • the invention also relates to a catalytic system comprising a composition of the type which has been described above, for example a system comprising a coating of known composition, in particular based on a refractory oxide (wash coat) and based on these compositions, on a substrate of the type, for example metallic or ceramic monolith.
  • a catalytic system comprising a composition of the type which has been described above, for example a system comprising a coating of known composition, in particular based on a refractory oxide (wash coat) and based on these compositions, on a substrate of the type, for example metallic or ceramic monolith.
  • the systems are mounted in a known manner in catalytic devices such as vehicle exhaust pipes in the case of application to the treatment of exhaust gases.
  • the invention therefore applies to the manufacture of catalysts or catalytic devices using the compositions or systems described above.
  • gases capable of being treated by the compositions of the present invention are, for example, those originating from gas turbines, boilers of thermal power stations or else from internal combustion engines, in particular from diesel engines or engines operating in lean mixture .
  • the invention applies to the treatment of gases which have a high oxygen content and which contain nitrogen oxides, with a view to reducing the emissions of these oxides.
  • the value ⁇ is correlated to the air / fuel ratio in a manner known per se in particular in the field of internal combustion engines.
  • the invention applies to the treatment of gases from systems of the type described in the previous paragraph and operating continuously under conditions such as ⁇ is always strictly greater than 1.
  • the invention also applies to the treatment of gases which have an oxygen content (expressed by volume) of at least 5%, more particularly at least 10%, this content being able for example be between 5 and 20%.
  • the gases can contain a reducing agent or be treated in the presence of a reducing agent such as a hydrocarbon and, in such a case, one of the reactions which it is sought to catalyze is the reaction HC (hydrocarbon) + NO x .
  • the hydrocarbons which can be used as a reducing agent for the elimination of NOx are in particular the gases or liquids of the families of saturated carbides, ethylenic carbides, acetylenic carbides, aromatic carbides and hydrocarbons from petroleum fractions such as for example methane , ethane, propane, butane, pentane, hexane, ethylene, propylene, acetylene, butadiene, benzene, toluene, xylene, kerosene and gas oil.
  • the gases can also contain, as reducing agent, organic compounds containing oxygen or be treated in the presence of these.
  • organic compounds may especially be alcohols of the type, for example saturated alcohols such as methanol, ethanol or propanol; ethers such as methyl ether or ethyl ether; esters such as methyl acetate and ketones.
  • the treatment process can be carried out on a gas without the presence of a reducing agent.
  • a reducing agent which comprise copper and at least one other element chosen from the groups Va, Illb, IVb and Vb of the periodic table and a support made of cerium oxide.
  • compositions are tested in the following manner to evaluate their catalytic performance.
  • the reaction mixture at the inlet of the reactor has the following composition (by volume):
  • the overall flow rate is 10 Nl / h.
  • the VVH is of the order of 10,000 h '1 .
  • the NO and NO x signals are given by a NO x ECOPHYSICS analyzer, based on the principle of chemistry-luminescence: it gives the values of NO and NO x .
  • the catalytic activity is measured from the NO and NO x signals as a function of the temperature during a programmed temperature rise from 20 to 700 ° C at a rate of 3.75 ° C / min and from the following relationships:
  • TNO NO conversion rate
  • This example relates to compositions based on niobium.
  • the support used is undoped alumina, calcined at 1090 ° C for 8 h to reduce its specific surface to 28 m 2 / g before deposition of the active elements.
  • the atomic content of active element is 10% calculated as follows:
  • the operating protocol is as follows:
  • Examples 1 -3, 1-4 and 1-5 show a very good level of activity, for the specific surface considered ( ⁇ 25 m 2 / g), with a maximum NO x conversion greater than 30% at 500 ° C approx.
  • the NO x conversion temperature range is very wide (between 350 ° C and 600 ° C approximately for an NO x conversion greater than 20%).
  • a reaction initiation temperature below 200 ° C for Examples 1-3 and 1-4, which is very advantageous for a diesel engine.
  • Example 1-1 the conversion takes place over a wide temperature range between about 250 ° C and 400 ° C.
  • the initiation temperature of the NO x conversion reaction is also less than 200 ° C.
  • Example 1-2 gives intermediate results between the previous examples.
  • This example relates to tantalum-based compositions.
  • Examples 2-3, 2-4 and 2-5 show a very good level of activity, for the specific surface considered ( ⁇ 25 m 2 / g), with a maximum NO x conversion greater than 30% at 500 ° C approx.
  • the NO x conversion temperature range is very wide between 350 ° C. and 550 ° C. approximately for an NO x conversion greater than 20%.
  • This example relates to a composition based on vanadium.
  • Copper nitrate (Cu (NO 3 ) 2 , 3H 2 O) and sodium orthovanadate (Na 3 VO 4 ) are used in aqueous solution.
  • the support used is the same as that of Example 1.
  • the vanadium and copper contents are identical to those of Example 1, as well as the operating protocol.
  • - a relatively wide activity temperature range, of approximately 100 ° C., between 450 ° C. and 550 ° C. in which the NO x conversion remains greater than 20%.
  • compositions based on a single active element This example illustrates compositions based on a single active element.
  • compositions are prepared with the same support as Example 1 and for niobium and tantalum the same precursors as Examples 1 and 2.
  • antimony the precursor is antimony tartrate; for vanadium, it is ammonium vanadate.
  • the products obtained have the following characteristics:
  • EXAMPLE 5 This example illustrates a composition based on antimony and copper on a titanium support.
  • the product is prepared in the same manner as in Example 1.
  • the precursor is tartrate.
  • the support is TiO 2 , a mixture of anatase and rutile with a surface area of 60 m 2 / g.
  • the product obtained has the following characteristics:
  • a composition based on niobium and gallium is prepared as in Example 1.
  • the support used is an alumina.
  • the test is carried out with a VVH of 100,000 h -1 and 150 mg of product.
  • This example relates to compositions based on copper.
  • the support used is undoped alumina, calcined at 1080 ° C for 8 h to reduce its specific surface to 37 m 2 / g before deposition of the active elements.
  • the atomic content of active element is 10% calculated as follows:
  • the operating protocol is as follows:
  • This example relates to compositions based on copper and comprising a CeO 2 support.
  • compositions are tested by using 50 mg of these in the form of powder with a particle size of 125-250 ⁇ m diluted in 150 mg of SiC with the same particle size.
  • the total gas flow rate is 30NI / h.
  • the WH is 500000h -1 .
  • composition of the treated gas mixture is that given above in the preamble to Example 1, with a CO content of 350 vpm.
  • the raw materials used are copper nitrate (Cu (NO 3 ) 2 , 3H 2 O), gallium nitrate (Ga (NO 3 ) 3 ) in solution, bismuth nitrate (Bi (NO 3 ) 3 5H 2 O), platinum (H 2 PtCl 6 ), an alcoholate and a niobium sol and a tin sol.
  • the niobium alcoholate is obtained by dissolving niobium chloride in an ethanolic medium at 70 ° C for 2 hours with stirring.
  • the niobium sol is obtained by precipitation of the niobium alcoholate in an ammoniacal medium.
  • the tin sol is prepared by adding volume to volume of a solution of NH 4 OH
  • the supports used are cerium oxide CeO 2 RHONE-POULENC
  • the atomic content of active element is 10% relative to the number of moles of the cerium oxide, ie:
  • the preparation method is a dry impregnation which is carried out under the same conditions as those of Example 1.
  • the calcination is carried out in air, at 750 ° C for 2 hours, mounted at 5 ° C / min.
  • the impregnation was done on a support doped with platinum, the amount of platinum in the composition being 2500 ppm. Niobium is introduced by the alcoholate.
  • Example 8-9 this example is carried out with the composition of example 8-8 but the catalyst was aged 6 hours at 750 ° C. under a gas flow of 100NI. h -1 to 10% of O 2 . 10% CO 2 and 10% 2 O.
  • the products were prepared by the atomization method.
  • a slip is formed having a concentration of reagents expressed as an oxide of 180 g / l. Niobium is introduced as a soil. This slip is then atomized with a Buchi atomizer with an inlet temperature of 220 ° C and an outlet temperature of 130 ° C. We calcine as in the previous examples.
  • Examples 8-1 and 8-2 demonstrate that the Cu-Sn / CeO 2 compounds are active with respect to the reduction of NO x emissions in the presence or not of a reducing agent of the HC type and / or CO. It will be noted that the catalytic activity is both higher and obtained at lower temperature in the absence of a reducing agent of the HC and / or CO type in the reaction mixture.
  • Examples 8-3 and 8-4 demonstrate that the Cu-Ga / CeO 2 compounds are active with respect to the reduction of NO x emissions in the presence or absence of a reducing agent of the HC type and / or CO. It will be noted that the catalytic activity is both higher and obtained at lower temperature in the absence of a reducing agent of the HC and / or CO type in the reaction mixture.
  • Examples 8-5 and 8-6 demonstrate that systems of the Cu-Nb / CeO 2 type are active with respect to the reduction of NO x emissions in the absence of a reducing agent of the HC type and / or CO. Formulations with an excess of Cu over Nb (expressed in atoms) are even more active under these conditions.
  • Examples 8-8 and 8-9 makes it possible to demonstrate the stability of the performance of the catalyst after a thermal aging treatment for 6 hours at 750 ° C. in the presence of water, CO 2 , and oxygen in the gas mixture.
  • the catalytic activity did not decrease as a result of this treatment.

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Abstract

Catalyst compositions for reducing nitrogen oxide emissions during gas processing. In a first embodiment, the compositions are characterised in that they are based on at least one element selected from the group which consists of tantalum, vanadium, niobium and antimony. In a second embodiment, they are characterised in that they are based on at least one element selected from a first group which includes tantalum, vanadium, niobium and antimony, plus at least one other element selected from a second group which includes copper, silver and gold. In a third embodiment, the compositions are based on at least one element selected from a first group which includes tantalum, vanadium, niobium, antimony and copper, plus at least one other element selected from a second group which includes zinc and the elements in groups IIIb, IVb and Vb of the periodic table. In a fourth embodiment, the compositions include copper and at least one other element selected from group VIa of the periodic table.

Description

COMPOSITIONS CATALYTIQUES POUR LA REDUCTION DES OXYDES D'AZOTE A BASE DE TANTALE. DE VANADIUM. DE NIOBIUM. DE CUIVRE OU D'ANTIMOINE  CATALYTIC COMPOSITIONS FOR THE REDUCTION OF TANTALUM-BASED NITROGEN OXIDES. OF VANADIUM. OF NIOBIUM. OF COPPER OR ANTIMONY
RHONE-POULENC CHIMIE RHONE-POULENC CHEMISTRY
La présente invention concerne des compositions catalytiques à base de tantale, de vanadium, de niobium, de cuivre ou d'antimoine pour la réduction des émissions des oxydes d'azote (NOx) dans le traitement d'un gaz . The present invention relates to catalytic compositions based on tantalum, vanadium, niobium, copper or antimony for the reduction of emissions of nitrogen oxides (NO x ) in the treatment of a gas.
On sait que la réduction des émissions des NOx des gaz d'échappement des moteurs d'automobile est effectuée à l'aide de catalyseurs 'trois voies' qui utilisent stoechiométriquement les gaz réducteurs présents dans le mélange. Tout excès d'oxygène se traduit par une détérioration brutale des performances du catalyseur.  It is known that the reduction of NOx emissions from exhaust gases from automobile engines is carried out using “three-way” catalysts which use the reducing gases present in the mixture stoichiometrically. Any excess oxygen results in a sudden deterioration in the performance of the catalyst.
Or, certains moteurs comme les moteurs diesel ou les moteurs essence fonctionnant en mélange pauvre (lean burn) sont économes en carburant mais émettent des gaz d'échappement qui contiennent en permanence un large excès d'oxygène de l'ordre de 5 à 15%. Un catalyseur trois voies standard est donc sans effet sur les émissions en NOx de ces moteurs. Par ailleurs, la limitation des émissions en NOx est rendue impérative par le durcissement des normes en post combustion automobile.  However, some engines such as diesel engines or gasoline engines operating in lean burn are fuel efficient but emit exhaust gases which permanently contain a large excess of oxygen of the order of 5 to 15% . A standard three-way catalyst therefore has no effect on the NOx emissions of these engines. In addition, limiting NOx emissions is made imperative by the tightening of standards in automotive post combustion.
II existe donc un besoin réel d'un catalyseur pour la réduction des émissions des There is therefore a real need for a catalyst for reducing emissions from
NOx. NOx.
Par ailleurs, il est intéressant de disposer de catalyseurs pouvant commencer à fonctionner à des températures relativement basses.  Furthermore, it is advantageous to have catalysts which can start to operate at relatively low temperatures.
L'objet de l'invention est donc de fournir une composition catalytique ayant un effet pour la réduction des NOx.  The object of the invention is therefore to provide a catalytic composition having an effect for the reduction of NOx.
Dans ce but, la composition catalytique selon un premier mode de réalisation de l'invention pour la réduction des émissions des oxydes d'azote dans le traitement d'un gaz à teneur élevée en oxygène est caractérisée en ce qu'elle est à base d'au moins un élément choisi dans le groupe comprenant le tantale, le vanadium, le niobium et l'antimoine.  For this purpose, the catalytic composition according to a first embodiment of the invention for the reduction of emissions of nitrogen oxides in the treatment of a gas with a high oxygen content is characterized in that it is based on '' at least one element chosen from the group comprising tantalum, vanadium, niobium and antimony.
Selon un autre mode de réalisation de l'invention, la composition catalytique est caractérisée en ce qu'elle est à base d'au moins un élément choisi dans un premier groupe comprenant le tantale, le vanadium, le niobium et l'antimoine et d'au moins un autre élément choisi dans un deuxième groupe comprenant le cuivre, l'argent et l'or.  According to another embodiment of the invention, the catalytic composition is characterized in that it is based on at least one element chosen from a first group comprising tantalum, vanadium, niobium and antimony and d '' at least one other element chosen from a second group comprising copper, silver and gold.
Selon un troisième mode de réalisation de l'invention, la composition catalytique est caractérisée en ce qu'elle est à base d'au moins un élément choisi dans un premier groupe comprenant le tantale, le vanadium, le niobium, l'antimoine et le cuivre, et d'au moins un autre élément choisi dans un deuxième groupe comprenant le zinc et les éléments des groupes IIIb, IVb et Vb de la classification périodique. According to a third embodiment of the invention, the catalytic composition is characterized in that it is based on at least one element chosen from a first group comprising tantalum, vanadium, niobium, antimony and copper, and at least at least one other element chosen from a second group comprising zinc and the elements of groups IIIb, IVb and Vb of the periodic table.
Selon un quatrième mode de réalisation de l'invention, la composition catalytique est caractérisée en ce qu'elle comprend du cuivre et au moins un autre élément choisi parmi le groupe Via de la classification périodique.  According to a fourth embodiment of the invention, the catalytic composition is characterized in that it comprises copper and at least one other element chosen from the group Via of the periodic table.
Les compositions de l'invention ont une action dans la réduction des émissions des oxydes d'azote soit dans le traitement des gaz soit en présence soit en absence d'un hydrocarbure et/ ou d'un composé organique contenant de l'oxygène. Dans certains cas, ces compositions sont efficaces à basse température.  The compositions of the invention have an action in reducing the emissions of nitrogen oxides either in the treatment of gases or in the presence or in the absence of a hydrocarbon and / or an organic compound containing oxygen. In some cases, these compositions are effective at low temperatures.
D'autres caractéristiques, détails et avantages de l'invention apparaîtront encore plus complètement à la lecture de la description qui va suivre, ainsi que des divers exemples concrets mais non limitatifs destinés à l'illustrer.  Other characteristics, details and advantages of the invention will appear even more completely on reading the description which follows, as well as various concrete but nonlimiting examples intended to illustrate it.
La classification périodique des éléments à laquelle il est fait référence dans la description est celle publiée dans le Supplément au Bulletin de la Société Chimique de France n° 1 (janvier 1966).  The periodic classification of the elements to which reference is made in the description is that published in the Supplement to the Bulletin of the French Chemical Society No. 1 (January 1966).
Comme on l'a indiqué plus haut et selon un premier mode de réalisation de l'invention, la composition catalytique comprend au moins un élément choisi parmi le tantale, le vanadium, le niobium et l'antimoine.  As indicated above and according to a first embodiment of the invention, the catalytic composition comprises at least one element chosen from tantalum, vanadium, niobium and antimony.
Selon le deuxième mode de réalisation de l'invention, la composition catalytique comprend deux catégories d'éléments. Elle comprend en effet au moins un élément choisi dans un premier groupe constitué du tantale, du vanadium, du niobium et de l'antimoine. Elle comprend en outre un second élément choisi dans un deuxième groupe constitué du cuivre, de l'argent et de l'or.  According to the second embodiment of the invention, the catalytic composition comprises two categories of elements. It in fact comprises at least one element chosen from a first group consisting of tantalum, vanadium, niobium and antimony. It also comprises a second element chosen from a second group consisting of copper, silver and gold.
Selon le troisième mode de réalisation de l'invention, la composition catalytique comprend encore deux catégories d'éléments. Elle comprend d'abord au moins un élément choisi dans un premier groupe constitué du tantale, du vanadium, du niobium, l'antimoine et le cuivre, et d'au moins un autre élément choisi dans un deuxième groupe comprenant le zinc et les éléments des groupes Illb, IVb et Vb de la classification périodique.  According to the third embodiment of the invention, the catalytic composition also comprises two categories of elements. It first comprises at least one element chosen from a first group consisting of tantalum, vanadium, niobium, antimony and copper, and at least one other element chosen from a second group comprising zinc and the elements of groups Illb, IVb and Vb of the periodic table.
En ce qui concerne les éléments du groupe IIIb, on utilisera plus particulièrement le gallium et l'indium.  As regards the elements of group IIIb, use will be made more particularly of gallium and indium.
Pour le groupe IVb, on citera l'étain en particulier et l'antimoine et le bismuth pour le groupe Vb.  For group IVb, mention will be made of tin in particular and antimony and bismuth for group Vb.
Les compositions selon le deuxième mode de réalisation et celles du troisième mode à base de tantale, de vanadium, de niobium et d'antimoine ont l'avantage d'être efficaces à température basse. Ainsi, on a pu mettre en évidence une activité de ces compositions à des températures aussi faibles que 300°C ou plus particulièrement aussi faibles que 200°C. Selon le quatrième mode de réalisation de l'invention, la composition comprend du cuivre et au moins un autre élément choisi parmi le groupe Via de la classification périodique. The compositions according to the second embodiment and those of the third embodiment based on tantalum, vanadium, niobium and antimony have the advantage of being effective at low temperature. Thus, it has been possible to demonstrate an activity of these compositions at temperatures as low as 300 ° C. or more particularly as low as 200 ° C. According to the fourth embodiment of the invention, the composition comprises copper and at least one other element chosen from the Via group of the periodic table.
Comme élément du groupe Via, on peut citer plus particulièrement le molydbène et le tungstène.  As an element of the Via group, there may be mentioned more particularly molydbene and tungsten.
Selon une variante particulière, les compositions de l'invention peuvent comprendre en outre un support.  According to a particular variant, the compositions of the invention can also comprise a support.
Comme support on peut employer tout support utilisé habituellement dans le domaine de la catalyse, comme, par exemple, ZrO2, AI2O3, TiO2 ou SiO2. les oxydes de lanthanides tel CeO2, ces supports pouvant être éventuellement dopés, ou encore les oxydes type spinelle, les zéolites, les silicates, les phosphates de silicoaluminium cristallins, les phosphates d'aluminium cristallins, ces silicates ou phosphates pouvant comprendre des substituants métalliques comme par exemple le titane, le fer, le magnésium, le zinc, le manganèse, le cobalt, le gallium, le lanthane, le cuivre, le molybdène, le chrome, le germanium ou le bore. As support, any support usually used in the field of catalysis can be used, such as, for example, ZrO 2 , AI 2 O 3 , TiO 2 or SiO 2 . lanthanide oxides such as CeO 2 , these supports possibly being doped, or alternatively spinel type oxides, zeolites, silicates, crystalline silicoaluminum phosphates, crystalline aluminum phosphates, these silicates or phosphates which can comprise metal substituents such as titanium, iron, magnesium, zinc, manganese, cobalt, gallium, lanthanum, copper, molybdenum, chromium, germanium or boron.
On peut utiliser plus particulièrement comme support AI2O3, TiO2, ZrO2, SiO2 et les spinelles comme par exemple MgAI2O4. One can use more particularly as support AI 2 O 3 , TiO 2 , ZrO 2 , SiO 2 and spinels like for example MgAI 2 O 4 .
Selon un mode de réalisation particulier de l'invention, on peut utiliser comme support l'oxyde de cérium.  According to a particular embodiment of the invention, cerium oxide can be used as a support.
Pour l'alumine, on peut mentionner notamment les alumines issues de la déshydratation rapide d'au moins un hydroxyde d'aluminium tel que la bayérite, l'hydrargillite ou gibbsite, la nordstrandite et/ou d'au moins un oxyhydroxyde d'aluminium tel que la boehmite, la pseudoboehmite et le diaspore.  For alumina, mention may in particular be made of aluminas resulting from the rapid dehydration of at least one aluminum hydroxide such as bayerite, hydrargillite or gibbsite, nordstrandite and / or at least one aluminum oxyhydroxide such as boehmite, pseudoboehmite and diaspore.
Selon une variante particulière on peut utiliser une alumine stabilisée. Comme élément stabilisant on peut citer les terres rares, le baryum, le silicium et le zirconium. Comme terre rare on peut mentionner tout particulièrement le lanthane ou le mélange lanthane néodyme.  According to a particular variant, it is possible to use a stabilized alumina. As stabilizing element, mention may be made of rare earths, barium, silicon and zirconium. As rare earth there may be mentioned very particularly lanthanum or the neodymium lanthanum mixture.
Pour l'oxyde de titane, on peut aussi utiliser un oxyde stabilisé par exemple par une terre rare comme le lanthane, le baryum, le strontium, le phosphore, le silicium, le zirconium ou l'aluminium.  For titanium oxide, it is also possible to use an oxide stabilized for example by a rare earth such as lanthanum, barium, strontium, phosphorus, silicon, zirconium or aluminum.
Les éléments décrits ci-dessus et constitutifs de la composition peuvent être présents dans celle-ci sous différents types de phases généralement sous forme d'oxydes ou d'oxydes mixtes, ces oxydes mixtes pouvant contenir certains éléments du support dans le cas des compositions supportées.  The elements described above and constituting the composition may be present in the latter under different types of phases generally in the form of oxides or mixed oxides, these mixed oxides possibly containing certain elements of the support in the case of the supported compositions .
Les quantités et notamment les quantités respectives des éléments constitutifs des compositions de l'invention peuvent varier dans de larges proportions. L'invention s'applique donc aux compositions dans lesquelles le tantale, le vanadium, le niobium, l'antimoine et le cuivre sont majoritaires en pourcentage atomique par rapport aux autres éléments comme à celles où ces autre éléments sont majoritaires. Dans le cas des compositions supportées, cette quantité est généralement comprise entre 1 et 50% et plus particulièrement, notamment dans le cas du cuivre, entre 10 et 50%, exprimée en teneur atomique en élément par rapport à la somme d'atomes d'éléments et de moles de support. The amounts and in particular the respective amounts of the constituent elements of the compositions of the invention can vary within wide proportions. The invention therefore applies to compositions in which tantalum, vanadium, niobium, antimony and copper are in the majority in atomic percentage relative to the other elements such as those where these other elements are in the majority. In the case of supported compositions, this amount is generally between 1 and 50% and more particularly, in particular in the case of copper, between 10 and 50%, expressed in atomic content of element relative to the sum of atoms of support elements and moles.
Les compositions de l'invention peuvent enfin comprendre des métaux précieux du type utilisé classiquement en catalyse et notamment en catalyse de post-combustion automobile.  The compositions of the invention can finally comprise precious metals of the type conventionally used in catalysis and in particular in catalysis of automobile afterburning.
On peut citer comme exemple de métaux, le platine, le palladium et le rhodium, le palladium étant préféré.  Mention may be made, as an example of metals, of platinum, palladium and rhodium, palladium being preferred.
Comme modes de réalisation particuliers de l'invention, on mentionnera enfin les compositions qui comprennent du cuivre et au moins un autre élément choisi dans les groupes Va, IIIb, IVb et Vb de la classification périodique et un support en oxyde de cérium.  As particular embodiments of the invention, mention will finally be made of compositions which comprise copper and at least one other element chosen from the groups Va, IIIb, IVb and Vb of the periodic table and a cerium oxide support.
Comme autre mode de réalisation particulier, on peut citer les compositions comprenant essentiellement les éléments mentionnés plus haut, c'est à dire les compositions dans lesquelles ce sont ces seuls éléments qui ont une action catalytique, en combinaison éventuellement avec des métaux précieux du type décrits ci-dessus.  As another particular embodiment, mention may be made of the compositions essentially comprising the elements mentioned above, that is to say the compositions in which it is these only elements which have a catalytic action, optionally in combination with precious metals of the type described. above.
Les compositions catalytiques de l'invention peuvent être préparées par tout procédé permettant d'obtenir un mélange intime des constituants des compositions de l'invention. Différents procédés peuvent être mentionnés à titre d'exemple.  The catalytic compositions of the invention can be prepared by any process which makes it possible to obtain an intimate mixture of the constituents of the compositions of the invention. Various methods can be mentioned by way of example.
Selon un premier procédé, ces compositions sont obtenues par chamottage de précurseurs des éléments et, le cas échéant, du support.  According to a first method, these compositions are obtained by chamotte of precursors of the elements and, where appropriate, of the support.
Ces précurseurs sont généralement des oxydes, des hydroxydes, des carbonates ou des oxalates. Ils sont mélangés et broyés puis éventuellement mis en forme sous pression, par exemple pastillés. Le mélange est ensuite calciné.  These precursors are generally oxides, hydroxides, carbonates or oxalates. They are mixed and ground then optionally shaped under pressure, for example pellets. The mixture is then calcined.
Selon un second procédé, on forme tout d'abord une solution ou une barbotine de sels des éléments et, le cas échéant, du support.  According to a second method, a solution or a slip of salts of the elements and, where appropriate, of the support is first formed.
A titre de sels, on peut choisir les sels d'acides inorganiques comme les nitrates, les sulfates ou les chlorures.  As salts, one can choose the salts of inorganic acids such as nitrates, sulfates or chlorides.
On peut aussi utiliser les sels d'acides organiques et notamment les sels d'acides carboxyliques aiiphatiques saturés ou les sels d'acides hydroxycarboxyiiques. A titre d'exemples, on peut citer les formiates, acétates, propionates, oxalates ou les citrates.  It is also possible to use the salts of organic acids and in particular the salts of saturated aiiphatic carboxylic acids or the salts of hydroxycarboxylic acids. By way of examples, mention may be made of formates, acetates, propionates, oxalates or citrates.
Ensuite, soit on fait précipiter la solution ou la barbotine par addition d'un agent précipitant en présence, le cas échéant, du support, soit on l'atomise avant calcination.  Then, either the solution or the slip is precipitated by adding a precipitating agent in the presence, if necessary, of the support, or it is atomized before calcination.
Dans ce dernier cas, on peut utiliser un sol à la place d'un sel des éléments.  In the latter case, a soil can be used instead of a salt of the elements.
Selon un autre procédé et dans le cas de compositions supportées, on procède par imprégnation du support par une solution ou un sol des éléments précités. Après imprégnation, le support est éventuellement séché puis il est calciné. Les solutions utilisables sont les mêmes que celles qui ont été décrites plus haut. Pour le tantale et le niobium on utilise plus généralement des solutions alcooliques de ces éléments, notamment des solutions de chlorures. According to another method and in the case of supported compositions, the process is carried out by impregnating the support with a solution or a soil of the abovementioned elements. After impregnation, the support is optionally dried and then it is calcined. The solutions that can be used are the same as those described above. For tantalum and niobium, alcoholic solutions of these elements are more generally used, in particular solutions of chlorides.
Pour la préparation par imprégnation d'une composition selon le second ou le troisième mode de réalisation de l'invention, on peut effectuer soit une co-imprégnation des éléments des différents groupes, soit procéder en deux temps.  For the preparation by impregnation of a composition according to the second or third embodiment of the invention, it is possible either to co-impregnate the elements of the different groups, or to proceed in two stages.
Dans ce cas, on imprègne d'abord le support par une solution d'un des deux groupes d'éléments. On sèche éventuellement le support. Dans un deuxième temps, on imprègne le support par une solution d'un élément de l'autre groupe. On sèche éventuellement et on calcine le support ainsi imprégné.  In this case, the support is first impregnated with a solution of one of the two groups of elements. The support is optionally dried. In a second step, the support is impregnated with a solution of an element from the other group. Optionally drying and calcining the support thus impregnated.
On utilise plus particulièrement l'imprégnation à sec. L'imprégnation à sec consiste à ajouter au produit à imprégner un volume d'une solution aqueuse de l'élément qui est égal au volume poreux du solide à imprégner.  More particularly, dry impregnation is used. Dry impregnation consists in adding to the product to be impregnated a volume of an aqueous solution of the element which is equal to the pore volume of the solid to be impregnated.
Les compositions de l'invention peuvent se présenter sous diverses formes telles que granulés, billes, cylindres ou nid d'abeille de dimensions variables.  The compositions of the invention can be in various forms such as granules, balls, cylinders or honeycomb of variable dimensions.
L'invention concerne aussi un système catalytique comprenant une composition du type qui a été décrit plus haut, par exemple un système comprenant un revêtement de composition connue, notamment à base d'un oxyde réfractaire (wash coat) et à base de ces compositions, sur un substrat du type par exemple monolithe métallique ou en céramique.  The invention also relates to a catalytic system comprising a composition of the type which has been described above, for example a system comprising a coating of known composition, in particular based on a refractory oxide (wash coat) and based on these compositions, on a substrate of the type, for example metallic or ceramic monolith.
Les systèmes sont montés d'une manière connue dans des dispositifs catalytiques comme les pots d'échappement des véhicules dans le cas de l'application au traitement des gaz d'échappement.  The systems are mounted in a known manner in catalytic devices such as vehicle exhaust pipes in the case of application to the treatment of exhaust gases.
L'invention s'applique donc à la fabrication de catalyseurs ou de dispositifs catalytiques utilisant les compositions ou les systèmes décrits ci-dessus.  The invention therefore applies to the manufacture of catalysts or catalytic devices using the compositions or systems described above.
Les gaz susceptibles d'être traités par les compositions de la présente invention sont, par exemple, ceux issus de turbines à gaz, de chaudières de centrales thermiques ou encore de moteurs à combustion interne, notamment de moteurs diesel ou de moteurs fonctionnant en mélange pauvre.  The gases capable of being treated by the compositions of the present invention are, for example, those originating from gas turbines, boilers of thermal power stations or else from internal combustion engines, in particular from diesel engines or engines operating in lean mixture .
L'invention s'applique au traitement des gaz qui présentent une teneur élevée en oxygène et qui contiennent des oxydes d'azote, en vue de réduire les émissions de ces oxydes. Par gaz présentant une teneur élevée en oxygène, on entend des gaz présentant en permanence un excès d'oxygène par rapport à la valeur stoechiométrique λ = 1. La valeur λ est corrélée au rapport air/carburant d'une manière connue en soi notamment dans le domaine des moteurs à combustion interne. En d'autres termes, l'invention s'applique au traitement des gaz issus de systèmes du type décrit au paragraphe précédent et fonctionnant en permanence dans des conditions telles que λ soit toujours strictement supérieur à 1. L'invention s'applique aussi au traitement des gaz qui présentent une teneur en oxygène (exprimée en volume) d'au moins 5%, plus particulièrement d'au moins 10%, cette teneur pouvant par exemple se situer entre 5 et 20%. The invention applies to the treatment of gases which have a high oxygen content and which contain nitrogen oxides, with a view to reducing the emissions of these oxides. By gas having a high oxygen content, one understands gases having permanently an excess of oxygen compared to the stoichiometric value λ = 1. The value λ is correlated to the air / fuel ratio in a manner known per se in particular in the field of internal combustion engines. In other words, the invention applies to the treatment of gases from systems of the type described in the previous paragraph and operating continuously under conditions such as λ is always strictly greater than 1. The invention also applies to the treatment of gases which have an oxygen content (expressed by volume) of at least 5%, more particularly at least 10%, this content being able for example be between 5 and 20%.
Les gaz peuvent contenir un réducteur ou être traités en présence d'un réducteur comme un hydrocarbure et, dans un tel cas, une des réactions que l'on cherche à catalyser est la réaction HC (hydrocarbure) + NOx. The gases can contain a reducing agent or be treated in the presence of a reducing agent such as a hydrocarbon and, in such a case, one of the reactions which it is sought to catalyze is the reaction HC (hydrocarbon) + NO x .
Les hydrocarbures qui peuvent être utilisés comme agent réducteur pour l'élimination des NOx sont notamment les gaz ou les liquides des familles des carbures saturés, des carbures éthyléniques, des carbures acétyléniques, des carbures aromatiques et les hydrocarbures des coupes pétrolières comme par exemple le méthane, l'éthane, le propane, le butane, le pentane, l'hexane, l'éthylène, le propylène, l'acétylène, le butadiène, le benzène, le toluène, le xylène, le kérosène et le gaz oil.  The hydrocarbons which can be used as a reducing agent for the elimination of NOx are in particular the gases or liquids of the families of saturated carbides, ethylenic carbides, acetylenic carbides, aromatic carbides and hydrocarbons from petroleum fractions such as for example methane , ethane, propane, butane, pentane, hexane, ethylene, propylene, acetylene, butadiene, benzene, toluene, xylene, kerosene and gas oil.
Les gaz peuvent contenir aussi à titre d'agent réducteur des composés organiques contenant de l'oxygène ou être traités en présence de ceux-ci. Ces composés peuvent être notamment les alcools du type par exemple alcools saturés comme le méthanol, l'éthanol ou le propanol; les éthers comme l'éther méthylique ou l'éther éthylique; les esters comme l'acétate de méthyle et les cétones.  The gases can also contain, as reducing agent, organic compounds containing oxygen or be treated in the presence of these. These compounds may especially be alcohols of the type, for example saturated alcohols such as methanol, ethanol or propanol; ethers such as methyl ether or ethyl ether; esters such as methyl acetate and ketones.
Il faut noter cependant que selon une caractéristique intéressante de l'invention, le procédé de traitement peut être réalisé sur un gaz sans la présence d'un réducteur. Cela s'applique tout particulièrement au cas des compositions qui comprennent du cuivre et au moins un autre élément choisi dans les groupes Va, Illb, IVb et Vb de la classification périodique et un support en oxyde de cérium.  It should be noted however that according to an advantageous characteristic of the invention, the treatment process can be carried out on a gas without the presence of a reducing agent. This applies particularly to the case of compositions which comprise copper and at least one other element chosen from the groups Va, Illb, IVb and Vb of the periodic table and a support made of cerium oxide.
Des exemples vont maintenant être donnés.  Examples will now be given.
Dans les exemples donnés ci-dessous et sauf indication contraire, les compositions sont testées de la manière suivante pour évaluer leurs performances catalytiques.  In the examples given below and unless otherwise indicated, the compositions are tested in the following manner to evaluate their catalytic performance.
1 ,5 g du catalyseur en poudre sont chargés dans un réacteur en quartz.  1.5 g of the powdered catalyst are loaded into a quartz reactor.
Le mélange réactionnel à l'entrée du réacteur a la composition suivante (en volume) :  The reaction mixture at the inlet of the reactor has the following composition (by volume):
- NO = 300 vpm  - NO = 300 vpm
- C3H6 = 300 vpm - C 3 H 6 = 300 vpm
- O2 = 10% - O 2 = 10%
- CO2 = 10% - CO 2 = 10%
- H2O = 10% - H 2 O = 10%
- N2 = qsp 100% - N 2 = qs 100%
Le débit global est de 10 Nl/h.  The overall flow rate is 10 Nl / h.
La VVH est de l'ordre de 10000 h'1. Les signaux de NO et NOx (NOx = NO + NO2) sont enregistrés en permanence ainsi que la température dans le réacteur. The VVH is of the order of 10,000 h '1 . The NO and NO x signals (NO x = NO + NO 2 ) are permanently recorded as well as the temperature in the reactor.
Les signaux de NO et NOx sont donnés par un analyseur de NOx ECOPHYSICS, basé sur le principe de la chimie-luminescence : il donne les valeurs de NO et NOx. The NO and NO x signals are given by a NO x ECOPHYSICS analyzer, based on the principle of chemistry-luminescence: it gives the values of NO and NO x .
L'activité catalytique est mesurée à partir des signaux NO et NOx en fonction de la température lors d'une montée en température programmée de 20 à 700°C à raison de 3,75°C/mn et à partir des relations suivantes : The catalytic activity is measured from the NO and NO x signals as a function of the temperature during a programmed temperature rise from 20 to 700 ° C at a rate of 3.75 ° C / min and from the following relationships:
- Le taux de conversion en NO (TNO) en % qui est donné par :  - The NO conversion rate (TNO) in% which is given by:
T(NO) = 100(NO°-NO)/ NO° avec NO° signal de NO à l'instant t = 0 qui correspond au signal de NO obtenu avec le mélange réactionnel lors du by-pass du réacteur catalytique et NO est le signal de NO à l'instant t.  T (NO) = 100 (NO ° -NO) / NO ° with NO ° NO signal at time t = 0 which corresponds to the NO signal obtained with the reaction mixture during the bypass of the catalytic reactor and NO is the NO signal at time t.
- Le taux de conversion globale des NOx (TNOx) en % qui est donné par : - The overall conversion rate of NO x (TNO x ) to% which is given by:
T(NOx) = 100(NOx°-NOx)/NOx° avec NOx° signal de NOx à l'instant t = 0 qui correspond au signal de NOx obtenu avec le mélange réactionnel lors du by-pass du réacteur catalytique et NOx est le signal de NOx à l'instant t. T (NO x ) = 100 (NO x ° -NO x ) / NO x ° with NO x ° signal of NO x at time t = 0 which corresponds to the signal of NO x obtained with the reaction mixture during the by- pass of the catalytic reactor and NO x is the signal of NO x at time t.
- Le taux de conversion des NOx en N2O (TN2O) en % qui est donné par : - The rate of conversion of NO x to N 2 O (TN 2 O) in% which is given by:
T(N2O) = 100(N2O-N2Oº)/NOx° avec N2Oº signal de N2O à l'instant t = 0 qui correspond au signal de N2O obtenu avec le mélange réactionnel lors du by-pass du réacteur catalytique et N2O est le signal de N2O à l'instant t. T (N 2 O) = 100 (N 2 ON 2 Oº) / NO x ° with N 2 Oº signal of N 2 O at time t = 0 which corresponds to the signal of N 2 O obtained with the reaction mixture during bypass of the catalytic reactor and N 2 O is the signal for N 2 O at time t.
Enfin, on entend par surface spécifique, la surface spécifique B.E.T. déterminée par adsorption d'azote conformément à la norme ASTM D 3663-78 établie à partir de la méthode BRUNAUER - EMMETT- TELLER décrite dans le périodique "The Journal of the American Society, 60, 309 (1938)". EXEMPLE 1  Finally, by specific surface is meant the specific surface B.E.T. determined by nitrogen adsorption in accordance with standard ASTM D 3663-78 established from the BRUNAUER - EMMETT-TELLER method described in the periodical "The Journal of the American Society, 60, 309 (1938)". EXAMPLE 1
Cet exemple concerne des compositions à base de niobium. This example relates to compositions based on niobium.
1) Synthèse des catalyseurs On utilise comme matières premières du nitrate de cuivre (Cu(NO3)2, 3H2O), du chlorure d'étain (SnCl4), du nitrate de gallium (Ga(NO3)3) en solution, du nitrate d'indium (ln(NO3)3) en solution, du nitrate de zinc (Zn(NO3)2) en solution et du chlorure de niobium (NbCl5). 1) Synthesis of the catalysts Copper nitrate (Cu (NO 3 ) 2 , 3H 2 O), tin chloride (SnCl4), gallium nitrate (Ga (NO 3 ) 3 ) in solution are used as raw materials. , indium nitrate (ln (NO 3 ) 3 ) in solution, zinc nitrate (Zn (NO 3 ) 2 ) in solution and niobium chloride (NbCl 5 ).
Le support utilisé est de l'alumine non dopée, calcinée à 1090°C pendant 8 h pour ramener sa surface spécifique à 28 m2/g avant dépôt des éléments actifs. The support used is undoped alumina, calcined at 1090 ° C for 8 h to reduce its specific surface to 28 m 2 / g before deposition of the active elements.
La teneur atomique en élément actif est de 10% calculé comme suit :  The atomic content of active element is 10% calculated as follows:
([Nb] + [X])/([Nb] + [X] + [AI2O3]) = 0,10 avec X = Cu, Zn, Ga, Sn ou In, où [ ] représente le nombre de moles de l'espèce considérée. La même teneur en niobium et en second élément dopant (5% atomique de chaque) a été déposée sur le support soit : ([Nb] + [X]) / ([Nb] + [X] + [AI 2 O 3 ]) = 0.10 with X = Cu, Zn, Ga, Sn or In, where [] represents the number of moles of the species considered. The same niobium and second doping element content (5 atomic% of each) was deposited on the support, namely:
([Nb]) / [Nb] + [X] + [AI2O3]) = 0,05 ([Nb]) / [Nb] + [X] + [AI 2 O 3 ]) = 0.05
([X]) / ([Nb] + [X] + [AI2O3]) = 0,05 ([X]) / ([Nb] + [X] + [AI 2 O 3 ]) = 0.05
avec X = Cu, Zn, Ga, Sn ou In.  with X = Cu, Zn, Ga, Sn or In.
Pour préparer les compositions catalytiques, le protocole opératoire est le suivant : To prepare the catalytic compositions, the operating protocol is as follows:
- Imprégnation à sec du premier élément à partir d'une solution alcoolique de niobium résultant de la dissolution de NbCI5 par de l'éthanol anhydre, l'alumine présentant un volume poreux de 0,70 cm3/g. - Dry impregnation of the first element from an alcoholic solution of niobium resulting from the dissolution of NbCl 5 with anhydrous ethanol, the alumina having a pore volume of 0.70 cm 3 / g.
- Séchage à l'étuve (110°C, 2 h).  - Drying in the oven (110 ° C, 2 h).
- Imprégnation à sec du second élément X (X = Cu, Zn, Ga, Sn, In), dans tous les cas sous la forme d'une solution aqueuse.  - Dry impregnation of the second element X (X = Cu, Zn, Ga, Sn, In), in all cases in the form of an aqueous solution.
- Séchage à l'étuve (110°C, 2 h).  - Drying in the oven (110 ° C, 2 h).
- Calcination sous air à 750 ou 950°C pendant 2 h, montée à 5°C/mn.  - Calcination in air at 750 or 950 ° C for 2 h, mounted at 5 ° C / min.
Les produits obtenus ont les caractéristiques suivantes :  The products obtained have the following characteristics:
Exemple 1-1 : [Nb] = 5% et [Cu] = 5% atomique, calcination à 750°C, SBET = 19,5 m2/g. Example 1-1: [Nb] = 5% and [Cu] = 5 atomic%, calcination at 750 ° C, SBET = 19.5 m 2 / g.
Exemple 1-2 : [Nb] = 5% et [Zn] = 5% atomique, calcination à 950°C, SBET = 24,5 m2/g. Example 1-2: [Nb] = 5% and [Zn] = 5 atomic%, calcination at 950 ° C, SBET = 24.5 m 2 / g.
Exemple 1-3 : [Nb] = 5% et [Ga] = 5% atomique, calcination à 750°C, SBET = 23,0 m2/g. Example 1-3: [Nb] = 5% and [Ga] = 5 atomic%, calcination at 750 ° C, SBET = 23.0 m 2 / g.
Exemple 1-4 : [Nb] = 5% et [Sn] = 5% atomique, calcination à 750°C, SBET = 24.5 m2/g. Example 1-4: [Nb] = 5% and [Sn] = 5 atomic%, calcination at 750 ° C, SBET = 24.5 m 2 / g.
Exemple 1-5 : [Nb] = 5% et [In] = 5% atomique, calcination à 750°C, Example 1-5: [Nb] = 5% and [In] = 5 atomic%, calcination at 750 ° C,
SBET = 21.5 m2/g. SBET = 21.5 m 2 / g.
2) Les performances catalytiques sont données dans les tableaux I à V ci-dessous : 2) The catalytic performances are given in Tables I to V below:
Figure imgf000011_0001
Figure imgf000011_0001
Figure imgf000011_0002
Figure imgf000012_0001
Figure imgf000011_0002
Figure imgf000012_0001
Figure imgf000012_0002
Figure imgf000013_0001
Figure imgf000012_0002
Figure imgf000013_0001
Les exemples 1 -3, 1-4 et 1-5 montrent un très bon niveau d'activité, pour la surface spécifique considérée (< 25 m2/g), avec un maximum de conversion de NOx supérieur à 30% à 500°C environ. De plus, la gamme de température de conversion NOx est très large (entre 350°C et 600°C environ pour une conversion NOx supérieure à 20%). Il faut noter aussi une température d'amorçage de la réaction inférieure à 200°C pour les exemples 1-3 et 1-4, ce qui est très intéressant pour un moteur Diesel. Examples 1 -3, 1-4 and 1-5 show a very good level of activity, for the specific surface considered (<25 m 2 / g), with a maximum NO x conversion greater than 30% at 500 ° C approx. In addition, the NO x conversion temperature range is very wide (between 350 ° C and 600 ° C approximately for an NO x conversion greater than 20%). Note also a reaction initiation temperature below 200 ° C for Examples 1-3 and 1-4, which is very advantageous for a diesel engine.
Dans le cas de l'exemple 1-1 , la conversion a lieu sur une large plage de température entre 250°C et 400°C environ. De plus, la température d'amorçage de la réaction de conversion des NOx est aussi inférieure à 200°C. In the case of Example 1-1, the conversion takes place over a wide temperature range between about 250 ° C and 400 ° C. In addition, the initiation temperature of the NO x conversion reaction is also less than 200 ° C.
L'exemple 1-2 donne des résultats intermédiaires entre les exemples précédents.  Example 1-2 gives intermediate results between the previous examples.
EXEMPLE 2 EXAMPLE 2
Cet exemple concerne des compositions à base de tantale.  This example relates to tantalum-based compositions.
1) Synthèse des catalyseurs  1) Synthesis of the catalysts
On utilise comme matières premières les mêmes que celles de l'exemple précédent ainsi que du chlorure de tantale (TaCl5) à la place du chlorure de niobium. The same materials as those of the previous example are used as raw materials as well as tantalum chloride (TaCl 5 ) in place of niobium chloride.
La teneur en tantale et en d'autres éléments sont identiques à celles de l'exemple 1 , la préparation des catalyseurs se fait suivant le même protocole.  The content of tantalum and of other elements are identical to that of Example 1, the preparation of the catalysts is carried out according to the same protocol.
Les produits obtenus ont les caractéristiques suivantes :  The products obtained have the following characteristics:
Exemple 2-1 ) : [Ta] = 5% et [Cu] = 5% atomique, calcination à 750°C, Example 2-1): [Ta] = 5% and [Cu] = 5 atomic%, calcination at 750 ° C,
SBET = 20,0 m2/g. Exemple 2-2 : [Ta] = 5% et [Zn] = 5% atomique, calcination à 950°C, SBETSBET = 20.0 m 2 / g. Example 2-2: [Ta] = 5% and [Zn] = 5 atomic%, calcination at 950 ° C, SBET
= 22,5 m2/g. = 22.5 m 2 / g.
Exemple 2-3 : [Ta] = 5% et [Ga] = 5% atomique, calcination à 950°C, SBET = 22,5 m2/g. Example 2-3: [Ta] = 5% and [Ga] = 5 atomic%, calcination at 950 ° C, SBET = 22.5 m 2 / g.
Exemple 2-4 : [Ta] = 5% et [Sn] = 5% atomique, calcination à 950°C, SBET Example 2-4: [Ta] = 5% and [Sn] = 5 atomic%, calcination at 950 ° C, SBET
= 22,5 m2/g. = 22.5 m 2 / g.
Exemple 2-5 : [Ta] = 5% et [In] = 5% atomique, calcination à 950°C, SBET Example 2-5: [Ta] = 5% and [In] = 5 atomic%, calcination at 950 ° C, SBET
= 20,5 m2/g. = 20.5 m 2 / g.
2) Les performances catalytiques sont données dans les tableaux VI à X ci-dessous. 2) The catalytic performances are given in Tables VI to X below.
Figure imgf000014_0001
Figure imgf000014_0001
Figure imgf000015_0001
Figure imgf000015_0001
Figure imgf000015_0002
Figure imgf000016_0001
Figure imgf000015_0002
Figure imgf000016_0001
Figure imgf000016_0002
Figure imgf000016_0002
Les exemples 2-3, 2-4 et 2-5 montrent un très bon niveau d'activité, pour la surface spécifique considérée (< 25 m2/g), avec un maximum de conversion de NOx supérieur à 30% à 500°C environ. De plus, pour les exemples 2-4 et 2-5, la gamme de température de conversion NOx est très large entre 350°C et 550°C environ pour une conversion NOx supérieure à 20%. EXEMPLE 3 Examples 2-3, 2-4 and 2-5 show a very good level of activity, for the specific surface considered (<25 m 2 / g), with a maximum NO x conversion greater than 30% at 500 ° C approx. In addition, for examples 2-4 and 2-5, the NO x conversion temperature range is very wide between 350 ° C. and 550 ° C. approximately for an NO x conversion greater than 20%. EXAMPLE 3
Cet exemple concerne une composition à base de vanadium.  This example relates to a composition based on vanadium.
1) Synthèse du catalyseur  1) Synthesis of the catalyst
On utilise du nitrate de cuivre (Cu(NO3)2, 3H2O) et de l'orthovanadate de sodium (Na3VO4) en solution aqueuse. Copper nitrate (Cu (NO 3 ) 2 , 3H 2 O) and sodium orthovanadate (Na 3 VO 4 ) are used in aqueous solution.
Le support utilisé est le même que celui de l'exemple 1.  The support used is the same as that of Example 1.
Les teneurs en vanadium et en cuivre sont identiques à celles de l'exemple 1 , de même que le protocole opératoire.  The vanadium and copper contents are identical to those of Example 1, as well as the operating protocol.
Le produit obtenu présente les caractéristiques suivantes :  The product obtained has the following characteristics:
Exemple 3-1 : [V] = 5% et [Cu] = 5% atomique, calcination à 750°C, SBET = 14,0 m2/g. Example 3-1: [V] = 5% and [Cu] = 5 atomic%, calcination at 750 ° C, SBET = 14.0 m 2 / g.
2) Les performances catalytiques apparaissent sur le tableau XI. Ces résultats montrent :  2) The catalytic performances appear on table XI. These results show:
- un bon niveau d'activité, pour la surface spécifique considérée (< 20 m2/g), avec un maximum de conversion de NOx de l'ordre de 65% à 500°C environ. - a good level of activity, for the specific surface considered (<20 m 2 / g), with a maximum conversion of NO x of the order of 65% at around 500 ° C.
- une plage de température d'activité relativement large, d'environ 100°C, entre 450°C et 550°C dans laquelle la conversion NOx reste supérieure à 20%. - a relatively wide activity temperature range, of approximately 100 ° C., between 450 ° C. and 550 ° C. in which the NO x conversion remains greater than 20%.
- une température d'amorçage de la réaction de conversion des NOx inférieure à 200°C. - an initiation temperature of the NO x conversion reaction of less than 200 ° C.
Figure imgf000017_0001
EXEMPLE 4
Figure imgf000017_0001
EXAMPLE 4
Cet exemple illustre des compositions à base d'un seul élément actif. This example illustrates compositions based on a single active element.
Ces compositions sont préparées avec le même support que l'exemple 1 et pour le niobium et le tantale les mêmes précurseurs que les exemples 1 et 2. Pour l'antimoine, le précurseur est le tartrate d'antimoine; pour le vanadium, il s'agit du vanadate d'ammonium. Les produits obtenus ont les caractéristiques suivantes : These compositions are prepared with the same support as Example 1 and for niobium and tantalum the same precursors as Examples 1 and 2. For antimony, the precursor is antimony tartrate; for vanadium, it is ammonium vanadate. The products obtained have the following characteristics:
- Exemple 4-1 [Sb] = 5% calcination à 950°C, 2 h. - Example 4-1 [Sb] = 5% calcination at 950 ° C, 2 h.
- Exemple 4-2 [Nb] = 5% calcination à 950°C, 2 h.  - Example 4-2 [Nb] = 5% calcination at 950 ° C, 2 h.
- Exemple 4-3 [Ta] = 5% calcination à 950°C, 2 h.  - Example 4-3 [Ta] = 5% calcination at 950 ° C, 2 h.
- Exemple 4-4 [V] = 5% calcination à 750°C, 2 h.  - Example 4-4 [V] = 5% calcination at 750 ° C, 2 h.
Les performances catalytiques sont données dans les tableaux XII à XV cidessous  The catalytic performances are given in Tables XII to XV below
Figure imgf000018_0001
Figure imgf000018_0001
Figure imgf000019_0001
Figure imgf000019_0001
Figure imgf000019_0002
Figure imgf000020_0001
Figure imgf000019_0002
Figure imgf000020_0001
EXEMPLE 5 Cet exemple illustre une composition à base d'antimoine et de cuivre sur un support titane. Le produit est préparé de la même manière que dans l'exemple 1. Pour l'antimoine, le précurseur est le tartrate. Le support est du TiO2, mélange d'anatase et de rutile de surface de 60 m2/g. Le produit obtenu a les caractéristiques suivantes : EXAMPLE 5 This example illustrates a composition based on antimony and copper on a titanium support. The product is prepared in the same manner as in Example 1. For antimony, the precursor is tartrate. The support is TiO 2 , a mixture of anatase and rutile with a surface area of 60 m 2 / g. The product obtained has the following characteristics:
- [Sb] = 7% et [Cu] = 3% calcination â 750°C 2h. SBET 26 m2/g - [Sb] = 7% and [Cu] = 3% calcination at 750 ° C 2h. SBET 26 m 2 / g
Les performances catalytiques sont données dans le tableau XVI. Pour déterminer ces performances, 0,75 g de catalyseur a été chargé dans le réacteur.
Figure imgf000021_0001
The catalytic performances are given in table XVI. To determine this performance, 0.75 g of catalyst was loaded into the reactor.
Figure imgf000021_0001
EXEMPLE 6 EXAMPLE 6
On prépare une composition à base de niobium et de gallium comme dans l'exemple 1.  A composition based on niobium and gallium is prepared as in Example 1.
Le support utilisé est une alumine.  The support used is an alumina.
Le produit obtenu a les caractéristiques suivantes :  The product obtained has the following characteristics:
[Nb] = 20% et [Ga] = 20% calcination à 750°C 2h. SBET 118 m2/g. [Nb] = 20% and [Ga] = 20% calcination at 750 ° C 2h. SBET 118 m 2 / g.
Le test est réalisé avec une V V H de 100000 h-1 et 150 mg de produit. The test is carried out with a VVH of 100,000 h -1 and 150 mg of product.
Les résultats sont donnés dans le tableau XVII. The results are given in Table XVII.
Figure imgf000022_0001
EXEMPLE 7
Figure imgf000022_0001
EXAMPLE 7
Cet exemple concerne des compositions à base de cuivre. This example relates to compositions based on copper.
1) Synthèse des catalyseurs On utilise comme matières premières du nitrate de cuivre (Cu(NO3)2, 3H2O), du nitrate de gallium (Ga(NO3)3) en solution, du nitrate d'indium (ln(NO3)3) en solution, du chlorure d'étain (SnCl4), du nitrate de zinc (Zn(NO3)2) en solution, du nitrate de bismuth en solution, du métatungstate d'ammonium ( (NH4)6H2W12O40 ) et de l'heptamolybdate d'ammonium ((NH4)6Mo7O24). 1) Synthesis of the catalysts Copper nitrate (Cu (NO 3 ) 2 , 3H 2 O), gallium nitrate (Ga (NO 3 ) 3 ) in solution, indium nitrate (ln ( NO 3 ) 3 ) in solution, tin chloride (SnCl 4 ), zinc nitrate (Zn (NO 3 ) 2 ) in solution, bismuth nitrate in solution, ammonium metatungstate ((NH 4 ) 6 H 2 W 12 O 40 ) and ammonium heptamolybdate ((NH 4 ) 6 Mo 7 O 24 ).
Le support utilisé est de l'alumine non dopée, calcinée à 1080°C pendant 8 h pour ramener sa surface spécifique à 37 m2/g avant dépôt des éléments actifs. The support used is undoped alumina, calcined at 1080 ° C for 8 h to reduce its specific surface to 37 m 2 / g before deposition of the active elements.
La teneur atomique en élément actif est de 10% calculé comme suit :  The atomic content of active element is 10% calculated as follows:
([Cu] + [X])/([Cu] + [X] + [AI2O3]) = 0,10 avec X = Mo, Ga, Sn, Zn, Bi, In et W. où [ ] représente le nombre de moles de l'espèce considérée ([Cu] + [X]) / ([Cu] + [X] + [AI 2 O 3 ]) = 0.10 with X = Mo, Ga, Sn, Zn, Bi, In and W. where [] represents the number of moles of the species considered
Pour préparer les compositions catalytiques, le protocole opératoire est le suivant : To prepare the catalytic compositions, the operating protocol is as follows:
- Imprégnation à sec du cuivre, l'alumine présentant un volume poreux de 0,70 cm3/g. - Dry impregnation of copper, alumina having a pore volume of 0.70 cm 3 / g.
- Séchage à l'étuve (110°C, 2 h).  - Drying in the oven (110 ° C, 2 h).
- Imprégnation à sec du second élément X .  - Dry impregnation of the second element X.
- Séchage à l'étuve (110°C, 2 h). - Calcination sous air à 750 pendant 2h, montée à 5°C/mn. - Drying in the oven (110 ° C, 2 h). - Calcination in air at 750 for 2h, mounted at 5 ° C / min.
Les produits obtenus ont les caractéristiques suivantes :  The products obtained have the following characteristics:
Exemple 7-1 : [Cu] = 5% et [Ga] = 5% atomique, calcination à 750°C,  Example 7-1: [Cu] = 5% and [Ga] = 5 atomic%, calcination at 750 ° C,
SBET = 23 m2/g. SBET = 23 m 2 / g.
Exemple 7-2 : [Cu] = 7% et [Mo] = 3% atomique, calcination à 750°C,  Example 7-2: [Cu] = 7% and [Mo] = 3 atomic%, calcination at 750 ° C,
SBET = 18.5 m2/g. SBET = 18.5 m 2 / g.
Exemple 7-3 : [Cu] = 9% et [Mo] = 1 % atomique, calcination à 750°C,  Example 7-3: [Cu] = 9% and [Mo] = 1 atomic%, calcination at 750 ° C,
SBET = 18,5 m2/g. SBET = 18.5 m 2 / g.
Exemple 7-4 : [Cu] = 5% et [Sn] = 5% atomique, calcination à 750°C,  Example 7-4: [Cu] = 5% and [Sn] = 5 atomic%, calcination at 750 ° C,
SBET = 18m2/g. SBET = 18m 2 / g.
Exemple 7-5 : [Cu] = 5% et [Zn] = 5% atomique, calcination à 750°C,  Example 7-5: [Cu] = 5% and [Zn] = 5 atomic%, calcination at 750 ° C,
BET = 23,5m2/g. BET = 23.5m 2 / g.
Exemple 7-6 : [Cu] = 5% et [Bi] = 5% atomique, calcination à 750°C.  Example 7-6: [Cu] = 5% and [Bi] = 5 atomic%, calcination at 750 ° C.
SBET = 18m2/g. SBET = 18m 2 / g.
Exemple 7-7 : [Cu] = 5% et [In] = 5% atomique, calcination à 750°C,  Example 7-7: [Cu] = 5% and [In] = 5 atomic%, calcination at 750 ° C,
SBET = 22m2/g. SBET = 22m 2 / g.
Exemple 7-8 : [Cu] = 5% et [W] = 5% atomique, dans ce cas on a procédé d'abord par l'imprégnation à sec du support par le métatungstate d'ammonium puis dans un deuxième temps on a réalisé l'imprégnation par le cuivre, calcination à 750°C, SBET = 25,3m2/g. Example 7-8: [Cu] = 5% and [W] = 5 atomic%, in this case we proceeded first by dry impregnation of the support with ammonium metatungstate then in a second step we have copper impregnation, calcination at 750 ° C, SBET = 25.3m 2 / g.
2) Les performances catalytiques sont données dans les tableaux XVIII à XXV ci- dessous 2) The catalytic performances are given in tables XVIII to XXV below
Figure imgf000024_0001
Figure imgf000024_0001
Figure imgf000024_0002
Figure imgf000025_0001
Figure imgf000024_0002
Figure imgf000025_0001
Figure imgf000025_0002
Figure imgf000026_0001
Figure imgf000026_0002
Figure imgf000026_0003
Figure imgf000027_0001
EXEMPLE 8
Figure imgf000025_0002
Figure imgf000026_0001
Figure imgf000026_0002
Figure imgf000026_0003
Figure imgf000027_0001
EXAMPLE 8
Cet exemple concerne des compositions à base de cuivre et comprenant un support en CeO2. This example relates to compositions based on copper and comprising a CeO 2 support.
Les compositions sont testées en mettant en oeuvre 50mg de celles-ci sous forme de poudre de granulométrie de 125-250μm dilués dans 150mg de SiC de même granulométrie.  The compositions are tested by using 50 mg of these in the form of powder with a particle size of 125-250 μm diluted in 150 mg of SiC with the same particle size.
Le débit total de gaz est de 30NI/ h. La WH est de 500000h-1. The total gas flow rate is 30NI / h. The WH is 500000h -1 .
La composition du mélange gazeux traité est celle donnée plus haut en préambule de l'exemple 1 avec en outre une teneur en CO de 350 vpm.  The composition of the treated gas mixture is that given above in the preamble to Example 1, with a CO content of 350 vpm.
Dans certains cas, le mélange gazeux traité ne comprend pas d'hydrocarbure et répond alors à la composition suivante : NO = 300 vpm, O2 = 10%, CO2 = 10%, H2O = 10% et N2 = qsp 100%. 1) Synthèse des catalyseurs In some cases, the treated gas mixture does not include any hydrocarbon and therefore corresponds to the following composition: NO = 300 vpm, O 2 = 10%, CO 2 = 10%, H 2 O = 10% and N 2 = qs 100%. 1) Synthesis of the catalysts
On utilise comme matières premières du nitrate de cuivre (Cu(NO3)2, 3H2O), du nitrate de gallium (Ga(NO3)3) en solution, du nitrate de bismuth (Bi(NO3)3 5H2O), du platine (H2PtCl6), un alcoolate et un sol de niobium et un sol d'étain. The raw materials used are copper nitrate (Cu (NO 3 ) 2 , 3H 2 O), gallium nitrate (Ga (NO 3 ) 3 ) in solution, bismuth nitrate (Bi (NO 3 ) 3 5H 2 O), platinum (H 2 PtCl 6 ), an alcoholate and a niobium sol and a tin sol.
L'alcoolate de niobium est obtenu par dissolution du chlorure de niobium en milieu éthanolique à 70°C pendant 2 heures sous agitation. Le sol de niobium est obtenu par précipitation de l'alcoolate de niobium en milieu ammoniacal. Le sol d'étain est préparé par ajout volume à volume d'une solution de NH4OHThe niobium alcoholate is obtained by dissolving niobium chloride in an ethanolic medium at 70 ° C for 2 hours with stirring. The niobium sol is obtained by precipitation of the niobium alcoholate in an ammoniacal medium. The tin sol is prepared by adding volume to volume of a solution of NH 4 OH
(1 ,70 mol/l) dans une solution de chlorure d'étain (SnCl4 0,50 mol/l). Après plusieurs lavages à l'aide d'un tampon ammoniacal au pH de précipitation (voisin de 8,7) pour éliminer les chlorures, le précipité est préparé par centrifugation et remis en suspension dans l'eau pour former un sol. (1.70 mol / l) in a solution of tin chloride (SnCl 4 0.50 mol / l). After several washes with an ammonia buffer with a precipitation pH (close to 8.7) to remove the chlorides, the precipitate is prepared by centrifugation and resuspended in water to form a sol.
Les supports utilisés sont de l'oxyde de cérium CeO2 RHONE-POULENC The supports used are cerium oxide CeO 2 RHONE-POULENC
La teneur atomique en élément actif est de 10% par rapport au nombre de moles de l'oxyde de cérium soit:  The atomic content of active element is 10% relative to the number of moles of the cerium oxide, ie:
([Cu] + [X])/([Cu] + [X] + [CeO2]) = 0.10 avec X = Sn, Nb, Ga ou Bi, ([Cu] + [X]) / ([Cu] + [X] + [CeO 2 ]) = 0.10 with X = Sn, Nb, Ga or Bi,
où [ ] représente le nombre de moles de l'élément considéré,  where [] represents the number of moles of the element considered,
soit encore :  either again:
[Cu] + [X] = 0,1 et [CeO2] = 0,9. [Cu] + [X] = 0.1 and [CeO 2 ] = 0.9.
La méthode de préparation est une imprégnation à sec qui s'effectue dans les mêmes conditions que celles de l'exemple 1. La calcination est réalisée sous air, à 750°C pendant 2 heures, montée à 5°C/min.  The preparation method is a dry impregnation which is carried out under the same conditions as those of Example 1. The calcination is carried out in air, at 750 ° C for 2 hours, mounted at 5 ° C / min.
Les produits obtenus ont les caractéristiques suivantes :  The products obtained have the following characteristics:
Exemple 8-1 et 8-2 : [Sn] = 5% atomique et [Cu] = 5% atomique. SBET = 63m2/g.Example 8-1 and 8-2: [Sn] = 5 atomic% and [Cu] = 5 atomic%. SBET = 63m 2 / g.
Exemple 8-3 et 8-4 : [Ga] = 5% atomique et [Cu] = 5% atomique. SBET = 60m2/g.Example 8-3 and 8-4: [Ga] = 5 atomic% and [Cu] = 5 atomic%. SBET = 60m 2 / g.
Exemple 8-7 : [Bi] = 5% atomique et [Cu] = 5% atomique, SBET = 31m2/g. Example 8-7: [Bi] = 5 atomic% and [Cu] = 5 atomic%, SBET = 31m 2 / g.
Exemple 8-8 : [Nb] = 3% atomique et [Cu] = 7% atomique, SBET = 63m2/g. Pour cet exemple, l'imprégnation a été faite sur un support dopé au platine, la quantité de platine au sein de la composition étant de 2500ppm. Le niobium est introduit par l'alcoolate. Example 8-8: [Nb] = 3 atomic% and [Cu] = 7 atomic%, SBET = 63m 2 / g. For this example, the impregnation was done on a support doped with platinum, the amount of platinum in the composition being 2500 ppm. Niobium is introduced by the alcoholate.
Exemple 8-9 : cet exemple est réalisé avec la composition de l'exemple 8-8 mais le catalyseur a été vieilli 6h à 750°C sous un débit gazeux de 100NI. h-1 à 10% de O2. 10% de CO2 et 10% dΗ2O. Example 8-9: this example is carried out with the composition of example 8-8 but the catalyst was aged 6 hours at 750 ° C. under a gas flow of 100NI. h -1 to 10% of O 2 . 10% CO 2 and 10% 2 O.
Pour les autres exemples, les produits ont été préparés par la méthode d'atomisation. On forme une barbotine présentant une concentration en réactifs exprimée en oxyde de 180g/l. Le niobium est introduit sous forme de sol. On atomise ensuite cette barbotine avec un atomiseur Buchi avec une température d'entrée de 220°C et une température de sortie de 130°C. On calcine comme dans les exemples précédents.  For the other examples, the products were prepared by the atomization method. A slip is formed having a concentration of reagents expressed as an oxide of 180 g / l. Niobium is introduced as a soil. This slip is then atomized with a Buchi atomizer with an inlet temperature of 220 ° C and an outlet temperature of 130 ° C. We calcine as in the previous examples.
Exemple 8-5 : [Nb] = 3% atomique et [Cu] = 7% atomique. SBET = 84m2/gExample 8-5: [Nb] = 3 atomic% and [Cu] = 7 atomic%. SBET = 84m 2 / g
Exemple 8- 6 [Nb] = 7% atomique et [Cu] = 3% atomique. SBET = 67m2/g Example 8- 6 [Nb] = 7 atomic% and [Cu] = 3 atomic%. SBET = 67m 2 / g
2) Les performances catalytiques sont données dans les tableaux XXVI à XXXIV ci-dessous.
Figure imgf000029_0001
2) The catalytic performances are given in tables XXVI to XXXIV below.
Figure imgf000029_0001
Figure imgf000030_0001
Figure imgf000030_0001
Les exemples 8-1 et 8-2 mettent en évidence que les composés Cu-Sn/CeO2 sont actifs vis-à-vis de la réduction des émissions de NOx en présence ou non d'un réducteur du type HC et/ou CO. On notera que l'activité catalytique est à la fois plus élevée et obtenue à plus basse température en l'absence de réducteur du type HC et/ou CO dans le mélange réactionnel. Examples 8-1 and 8-2 demonstrate that the Cu-Sn / CeO 2 compounds are active with respect to the reduction of NO x emissions in the presence or not of a reducing agent of the HC type and / or CO. It will be noted that the catalytic activity is both higher and obtained at lower temperature in the absence of a reducing agent of the HC and / or CO type in the reaction mixture.
Figure imgf000031_0001
Figure imgf000031_0001
Figure imgf000031_0002
Les exemples 8-3 et 8-4 mettent en évidence que les composés Cu-Ga/CeO2 sont actifs vis-à-vis de la réduction des émissions de NOx en présence ou non d'un réducteur du type HC et/ou CO. On notera que l'activité catalytique est à la fois plus élevée et obtenue à plus basse température en l'absence de réducteur du type HC et/ou CO dans le mélange réactionnel.
Figure imgf000031_0002
Examples 8-3 and 8-4 demonstrate that the Cu-Ga / CeO 2 compounds are active with respect to the reduction of NO x emissions in the presence or absence of a reducing agent of the HC type and / or CO. It will be noted that the catalytic activity is both higher and obtained at lower temperature in the absence of a reducing agent of the HC and / or CO type in the reaction mixture.
Figure imgf000032_0001
Figure imgf000032_0001
Figure imgf000033_0001
Figure imgf000033_0001
Les exemples 8-5 et 8-6 mettent en évidence que les systèmes du type Cu- Nb/CeO2 sont actifs vis-à-vis de la réduction des émissions de NOx en l'absence de réducteur du type HC et/ou CO. Les formulations avec un excès de Cu par rapport au Nb (exprimé en atomes) sont encore plus actives dans ces conditions. Examples 8-5 and 8-6 demonstrate that systems of the Cu-Nb / CeO 2 type are active with respect to the reduction of NO x emissions in the absence of a reducing agent of the HC type and / or CO. Formulations with an excess of Cu over Nb (expressed in atoms) are even more active under these conditions.
Figure imgf000034_0001
Figure imgf000034_0001
Figure imgf000034_0002
Figure imgf000035_0001
Figure imgf000034_0002
Figure imgf000035_0001
La comparaison des exemples 8-8 et 8-9 permet de mettre en évidence la stabilité des performances du catalyseur après un traitement de vieillissement thermique de 6 heures à 750°C en présence d'eau, de CO2, et d'oxygène dans le mélange gazeux. L'activité catalytique n'a pas diminué du fait de ce traitement. The comparison of Examples 8-8 and 8-9 makes it possible to demonstrate the stability of the performance of the catalyst after a thermal aging treatment for 6 hours at 750 ° C. in the presence of water, CO 2 , and oxygen in the gas mixture. The catalytic activity did not decrease as a result of this treatment.

Claims

REVENDICATIONS
1- Composition catalytique pour la réduction des émissions des oxydes d'azote dans le traitement d'un gaz à teneur élevée en oxygène, caractérisée en ce qu'elle est à base d'au moins un élément choisi dans le groupe comprenant le tantale, le vanadium, le niobium et l'antimoine. 1- Catalytic composition for reducing emissions of nitrogen oxides in the treatment of a gas with a high oxygen content, characterized in that it is based on at least one element chosen from the group comprising tantalum, vanadium, niobium and antimony.
2- Composition catalytique pour la réduction des émissions des oxydes d'azote dans le traitement d'un gaz à teneur élevée en oxygène, caractérisée en ce qu'elle est à base d'au moins un élément choisi dans un premier groupe comprenant le tantale, le vanadium, le niobium et l'antimoine et d'au moins un autre élément choisi dans un deuxième groupe comprenant le cuivre, l'argent et l'or. 2- Catalytic composition for reducing emissions of nitrogen oxides in the treatment of a gas with a high oxygen content, characterized in that it is based on at least one element chosen from a first group comprising tantalum , vanadium, niobium and antimony and at least one other element chosen from a second group comprising copper, silver and gold.
3- Composition catalytique pour la réduction des émissions des oxydes d'azote dans le traitement d'un gaz à teneur élevée en oxygène, caractérisée en ce qu'elle est à base d'au moins un élément choisi dans un premier groupe comprenant le tantale, le vanadium, le niobium, l'antimoine et le cuivre, et d'au moins un autre élément choisi dans un deuxième groupe comprenant le zinc et les éléments des groupes Illb, IVb et Vb de la classification périodique. 3- Catalytic composition for the reduction of emissions of nitrogen oxides in the treatment of a gas with a high oxygen content, characterized in that it is based on at least one element chosen from a first group comprising tantalum , vanadium, niobium, antimony and copper, and at least one other element chosen from a second group comprising zinc and the elements of groups Illb, IVb and Vb of the periodic table.
4- Composition catalytique pour la réduction des émissions des oxydes d'azote dans le traitement d'un gaz à teneur élevée en oxygène, caractérisée en ce qu'elle comprend du cuivre et au moins un autre élément choisi parmi le groupe Via de la classification périodique. 4- Catalytic composition for the reduction of emissions of nitrogen oxides in the treatment of a gas with a high oxygen content, characterized in that it comprises copper and at least one other element chosen from the Via group of the classification periodic.
5- Composition selon la revendication 3, caractérisée en ce que les éléments du groupe Illb sont le gallium ou l'indium, celui du groupe IVb l'étain et ceux du groupe Vb, l'antimoine ou le bismuth. 5- Composition according to claim 3, characterized in that the elements of the group Illb are gallium or indium, that of the group IVb tin and those of the group Vb, antimony or bismuth.
6- Composition selon la revendication 4, caractérisée en ce que les éléments du groupe Via sont le molybdène et le tungstène. 6- Composition according to claim 4, characterized in that the elements of the Via group are molybdenum and tungsten.
7- Composition selon l'une des revendications précédentes, caractérisée en ce qu'elle comprend en outre un support et, plus particulièrement, un support choisi parmi l'alumine, la silice, l'oxyde de titane, l'oxyde de zirconium, les oxydes de lanthanides, les oxydes de type spinelle, les zéolites, les silicates, les phosphates de silicoaiuminium cristallins, les phosphates d'aluminium cristallins. 7- Composition according to one of the preceding claims, characterized in that it further comprises a support and, more particularly, a support chosen from alumina, silica, titanium oxide, zirconium oxide, lanthanide oxides, spinel-type oxides, zeolites, silicates, crystalline silicon phosphates, crystalline aluminum phosphates.
8- Composition selon la revendication 7, caractérisée en ce qu'elle comprend un support en oxyde de cérium. 8- Composition according to claim 7, characterized in that it comprises a support in cerium oxide.
9- Composition selon l'une des revendications précédentes, caractérisée en ce qu'elle comprend du cuivre et au moins un autre élément choisi dans les groupes Va, Illb, IVb et Vb de la classification périodique et un support en oxyde de cérium. 9- Composition according to one of the preceding claims, characterized in that it comprises copper and at least one other element chosen from the groups Va, Illb, IVb and Vb of the periodic table and a support made of cerium oxide.
10 - Système catalytique caractérisé en ce qu'il comprend une composition selon l'une des revendications précédentes. 10 - Catalytic system characterized in that it comprises a composition according to one of the preceding claims.
11- Procédé de traitement des gaz à teneur élevée en oxygène pour la réduction des émissions des oxydes d'azote, notamment pour le traitement des gaz d'échappement de moteurs à combustion interne, caractérisé en ce qu'on utilise une composition catalytique selon l'une des revendications 1à 9 ou un système selon la revendication 10. 11- Process for the treatment of gases with a high oxygen content for the reduction of emissions of nitrogen oxides, in particular for the treatment of exhaust gases from internal combustion engines, characterized in that a catalytic composition according to l one of claims 1 to 9 or a system according to claim 10.
12- Procédé selon la revendication 11 , caractérisé en ce qu'on traite un gaz en présence d'un réducteur du type notamment hydrocarbure ou composé organique contenant de l'oxygène. 12- A method according to claim 11, characterized in that a gas is treated in the presence of a reducing agent of the type in particular hydrocarbon or organic compound containing oxygen.
13- Procédé selon la revendication 1 1 , caractérisé en ce qu'on traite un gaz en l'absence d'un réducteur. 13- A method according to claim 1 1, characterized in that a gas is treated in the absence of a reducing agent.
14- Utilisation d'une composition selon l'une des revendications 1 à 9 ou d'un système catalytique selon la revendication 10 à la fabrication de catalyseurs ou de dispositifs catalytiques pour post combustion automobile. 14- Use of a composition according to one of claims 1 to 9 or of a catalytic system according to claim 10 in the manufacture of catalysts or catalytic devices for automotive post combustion.
PCT/FR1995/001302 1994-10-13 1995-10-06 Nitrogen oxide reducing catalyst compositions based on tantalum, vanadium, niobium, copper or antimony WO1996011740A1 (en)

Priority Applications (7)

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AU36567/95A AU700120B2 (en) 1994-10-13 1995-10-06 Catalytic compositions for the reduction of nitrogen oxides, based on tantalum, vanadium, niobium, copper or antimony
MX9702654A MX9702654A (en) 1994-10-13 1995-10-06 Nitrogen oxide reducing catalyst compositions based on tantalum, vanadium, niobium, copper or antimony.
BR9509354A BR9509354A (en) 1994-10-13 1995-10-06 Catalytic composition for the reduction of nitrogen oxide emissions in the treatment of a gas with high oxygen content catalytic system process for the treatment of gases with a high oxygen content for the reduction of nitrogen oxide emissions and the use of the composition or system catalytic
JP8512976A JPH10502020A (en) 1994-10-13 1995-10-06 Catalyst compositions for reducing nitrogen oxides based on tantalum, vanadium, niobium, copper or antimony
KR1019970702403A KR970706888A (en) 1994-10-13 1995-10-06 A catalyst composition for reducing nitrogen oxides based on tantalum, vanadium, niobium, copper or antimony (NITROGEN OXIDE REDUCING CATALYST COMPOSITIONS BASED ON TANTALUM, VANADIUM, NIOBIUM, COPPER OR ANTIMONY)
EP95934177A EP0785820A1 (en) 1994-10-13 1995-10-06 Nitrogen oxide reducing catalyst compositions based on tantalum, vanadium, niobium, copper or antimony
FI971497A FI971497A (en) 1994-10-13 1997-04-10 Tantalum, vanadium, niobium, copper, or antinomic-based nitric oxide reduction catalyst mixtures

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FR94/12200 1994-10-13
FR9412200A FR2725638A1 (en) 1994-10-13 1994-10-13 Novel nitrous oxide redn. catalytic compsns.
FR9414511A FR2727636A1 (en) 1994-12-02 1994-12-02 Novel nitrous oxide redn. catalytic compsns.
FR94/14511 1994-12-02

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