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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