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
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
  • B01J21/063—Titanium; Oxides or hydroxides thereof
• • 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
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
  • B01J21/08—Silica
• • 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
  • 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
  • B01D53/9427—Processes characterised by a specific catalyst for removing nitrous oxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
  • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
  • B01J23/42—Platinum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
  • B01J35/45—Nanoparticles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0201—Impregnation
  • B01J37/0211—Impregnation using a colloidal suspension
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/08—Heat treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2251/00—Reactants
  • B01D2251/20—Reductants
  • B01D2251/21—Organic compounds not provided for in groups B01D2251/206 or B01D2251/208
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/10—Noble metals or compounds thereof
  • B01D2255/102—Platinum group metals
  • B01D2255/1021—Platinum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/20—Metals or compounds thereof
  • B01D2255/206—Rare earth metals
  • B01D2255/2063—Lanthanum
• • 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
  • B01D2255/20707—Titanium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/30—Silica
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
  • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
• • 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)
• • 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
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies

Definitions

• the present invention relates to a gas treatment process for the reduction of emissions of nitrogen oxides using a catalytic composition with a support based on silica and titanium oxide.
• NOx nitrogen oxides
• the reduction of emissions of nitrogen oxides (NOx) from the exhaust gases of automobile engines in particular 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.
• certain 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 at least 5% for example.
• a standard three-way catalyst therefore has no effect on the NOx emissions of these engines.
• the limitation of NOx emissions is made imperative by the tightening of standards in automotive post combustion which now extend to this type of engine.
• the process of the invention for the treatment of gases for the reduction of emissions of nitrogen oxides, is of the type in which a catalytic composition is used comprising a catalytic phase on a support and it is characterized in that that the support is based on silica and titanium oxide in an atomic proportion Ti / Ti + Si of between 0.1 and 15%.
• the main characteristic of the catalytic composition used in the process of the invention resides in the support of this composition.
• This support is based on silica and titanium oxide in the specific proportion which has been given above.
• this proportion can be between 1 and
• supports having a high specific surface area and thermally stable are advantageously use.
• the term “specific surface” is understood here to mean the BET specific surface area determined by nitrogen adsorption in accordance with standard AST D 3663-78 established on the basis of the BRUNAUER - E METT-TELLER method described in the periodical "The Journal of the American Society, ⁇ , 309 (1938) ".
• the supports with these surface values are generally of the mesoporous type, that is to say that they have the characteristic of having a significant pore volume provided by mesopores (pores with a diameter between 2 and 10 nm).
• the support based on silica and titanium oxide can be prepared by any process capable of leading to a support of sufficient specific surface.
• organic silicon compounds are generally used in the form of solutions in alcohols, in particular in aliphatic alcohols.
• titanium compound there may be used organic titanium compounds such as the alkyl- or alkoxy-titanates which are generally employed in the form of alcoholic solutions as for the silicon compound.
• the surfactant it is possible to use more particularly those of the active cation type such as amides and quaternary ammonium salts.
• the reaction can be carried out by mixing the organic silicon compound and the titanium compound and then heating.
• the surfactant is then added to the mixture thus heated.
• the precipitate obtained after the reaction is separated from the reaction medium.
• This precipitate is then calcined, generally in air, to obtain the support which can then be shaped.
• Calcination can be done in two parts. In the first part, calcination is carried out at a temperature sufficient to remove the surfactant. This temperature can be around 650 ° C. In the second part, calcination is carried out at a temperature at least equal to that at which the catalyst will be used. This temperature can be . about 750 ° C.
• the support can be in various forms such as granules, balls, cylinders or honeycomb of variable dimensions.
• the support can comprise, as additives, one or more rare earth oxides.
• rare earth is meant the elements of the group constituted by yttrium and the elements of the periodic classification of atomic number included inclusively between 57 and 71. Mention may be made, as rare earth, of lanthanum more particularly.
• the additive content expressed in atomic% additive / Ti + Si + additive may be at most 20%, more particularly at most 10%.
• the catalytic composition of the invention can also comprise a catalytic phase.
• This phase can be based on at least one metal chosen from the elements included in groups IIIA to IIB of the periodic table.
• the catalytic phase is based on at least one metal chosen from the metals of group VIII of the periodic table.
• metals which can be used in the catalytic phase include platinum, palladium, rhodium, ruthenium, iridium. Mention may also be made of iron, copper, chromium as well as vanadium, niobium, tantalum, molybdenum and tungsten.
• the metal content of the catalytic phase and, in particular of platinum, of the composition can vary within wide proportions. Usually, this proportion, expressed by weight of metal relative to the weight of the support is between 500 and 40,000 ppm, preferably between 2,500 and 20,000 ppm and even more particularly between 5,000 and 15,000 ppm.
• the catalytic phase can be deposited on the support, preferably the calcined support, by any known technique.
• the platinum is provided in the form of a sol.
• the platinum sol will preferably be chosen to have a size of colloids between 2 nm and 10 nm and more particularly between 3 nm and 8 nm.
• the size of colloids is determined by electron transmission microscopy (TEM).
• the impregnation is carried out "dry", that is to say that the total volume of solution or soil used is approximately equal to the total pore volume developed by the support to be impregnated. Concerning the determination of this pore volume, it can be carried out according to the method known with a mercury porosimeter or by measuring the amount of water absorbed by a sample.
• the support is optionally dried and then it is calcined.
• the drying is most often carried out in air, at a temperature which can vary between 80 and 300 ° C. and preferably chosen between 100 and 150 ° C. Drying continues until obtaining a constant weight. Generally, the drying time is between 1 and 24 hours.
• the calcination of the support with the catalytic or active phase deposited is generally carried out at a temperature of at most 750 ° C and more particularly at most 550 ° C in the case where platinum is used in the catalytic phase.
• the duration of the calcination can, for its part, vary within wide limits, for example between 1 and 24 hours, preferably between 2 and 10 hours. Calcination is generally carried out in air, but calcination carried out for example under inert gas is obviously not excluded.
• the size of the platinum particles in the composition after calcination is substantially identical to that of the colloids mentioned above.
• the deposition of the catalytic phase can also be done by atomization.
• the support is introduced, for example in the form of a suspension, into a solution or a sol of the element or elements constituting the catalytic phase and the mixture thus formed is spray-dried.
• One can operate with a gas outlet temperature between 100 and 150 ° C. Then calcined under the conditions described above.
• gases which may comprise nitrogen oxides in combination optionally with carbon oxides and / or hydrocarbons, with a view to reducing the emissions of nitrogen oxides in particular.
• gases capable of being treated by the present invention are, for example, those originating from gas turbines, boilers of thermal power stations or even internal combustion engines. In the latter case, it may in particular be diesel engines or engines operating in a lean mixture.
• the value ⁇ is correlated with 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 that ⁇ is always strictly greater than 1.
• the invention thus applies, on the one hand, to the treatment of engine gases operating in a lean burn mixture and which have an oxygen content (expressed by volume) generally between 2.5 and 5% and, on the other hand, to the treatment of gases which have an even higher oxygen content, for example gases from engines of the diesel type, that is to say at least 5% or more than 5% , more particularly at least 10%, this content can for example be between 5 and 20%.
• the gases can contain hydrocarbons and, in such a case, one of the reactions which one seeks to catalyze is the reaction HC (hydrocarbons) + NO x .
• the hydrocarbons which can be used as a reducing agent for the elimination of NOx are in particular the gases or the 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.
• organic compounds containing oxygen 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 invention also applies to the treatment of gases containing no hydrocarbons or organic compounds as a reducing agent.
• the invention also relates to a catalytic system for the treatment of gases with a view to reducing the emissions of nitrogen oxides, gases which may be of the type mentioned above.
• This system is characterized in that it comprises a catalytic composition such as that described above.
• the catalytic composition can be in various forms such as granules, beads, cylinders or honeycomb of variable dimensions.
• compositions can also be used in catalytic systems comprising a coating (wash coat) incorporating these compositions, the coating being arranged on a substrate of the type, for example metallic or ceramic monolith.
• a coating wash coat
• the systems are mounted in a known manner in the exhaust pipes of vehicles in the case of application to the treatment of exhaust gases.
• the invention also relates to the process for manufacturing the above-mentioned catalytic systems using a catalytic composition of the type described above.
• the support used has an Ti / Ti + Si atomic proportion of 9% and it is prepared as follows:
• TEOS tetraethyte orthosilicates
• the titanium alkoxide solution is rapidly added with vigorous stirring to the TEOS solution.
• a clear solution is then obtained which is heated to 72 ° C. with stirring for 3 hours.
• a solution containing 0.27 mole of dodecylamine is prepared.
• the solution containing the TEOS mixture and is then added to the solution containing the surfactant DDA.
• the whole is kept under vigorous stirring for 18 hours at room temperature.
• the surfactant is removed by calcining the precipitate thus obtained in air at a temperature of 650 ° C. for 4 hours.
• the precipitate is calcined for 4 hours at 750 ° C in air (temperature rise rate 1 ° C / min).
• the support thus prepared is dry impregnated with platinum in Droportions of 1 or 2% by weight.
• the impregnated support is dried in an oven at 110 ° C. for 2 hours, then calcined under the conditions given in the table below. - Products obtained
• the powdered catalyst 50 mg are loaded into a quartz reactor.
• the powder used was previously granulated at 0.125 and 0.250 mm.
• the reaction mixture at the inlet of the reactor has the following composition (by volume):
• the overall flow is 30 Nl h.
• the WH is around 500,000 h * 1 .
• the HC signal is given by a BECKMAN detector of the total hydrocarbon type, based on the principle of detection by flame ionization.
• the NO x signal is given by a NO x ECOPHYSICS analyzer, based on the principle of chemistry-luminescence.
• the CO and N 2 O signal is given by a ROSEMOUNT infrared analyzer.
• the catalytic activity is measured from the HC (C3H6), CO and NO x signals as a function of the temperature during a programmed temperature rise from 150 to 700 ° C at a rate of 15 ° C / min and from the following relationships:
• TCO CO conversion rate
• the catalysts can activate under the conditions of the tests, the catalytic activity is given during the second consecutive passage in the test under the same conditions.
• Product 1 is used (catalyst used for NOx reduction). The results are given in Table 1 below.
• Product 1 is used but with a gas mixture which no longer contains CO or C3H6 (catalyst used in direct decomposition). The results are given in Table 2 below.
• Product 2 (catalyst used for NOx reduction) is used. The results are given in Table 3 below.
• Product 2 is used but with a gas mixture which no longer contains CO or C3H6 (catalyst used in direct decomposition). The results are given in Table 4 below.
• Product 4 is used but with a gas mixture which no longer contains CO or C3H6 (catalyst used in direct decomposition). The results are given in Table 6 below.
• Product 5 is used but with a gas mixture which no longer contains CO or C3H5 (catalyst used in direct decomposition). The results are given in Table 7 below.
• a catalytic composition based on platinum is used on a titanium support comprising lanthanum.
• the impregnation is followed by drying in an oven (110 ° C, 2 h), calcination at 500 ° C for 2 h with a rise in temperature to 1 ° C / min.
• the platinum content is 1%.
• the catalyst thus prepared is used under the abovementioned conditions in reduction. The results are given in Table 8 below. Table 8
• composition according to the invention makes it possible to obtain a catalytic activity in a temperature window of 250 to 400 ° C. Furthermore, the compositions obtained from a platinum sol and used in the presence of a reducing agent can exhibit an increased and maximum catalytic activity from 250 ° C. and which manifests itself from the first pass.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Environmental & Geological Engineering (AREA)
• Health & Medical Sciences (AREA)
• Biomedical Technology (AREA)
• Combustion & Propulsion (AREA)
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• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Catalysts (AREA)
• Exhaust Gas Treatment By Means Of Catalyst (AREA)
• Exhaust Gas After Treatment (AREA)

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• 1997
  • 1997-07-03 FR FR9708422A patent/FR2765492B1/fr not_active Expired - Fee Related
• 1998
  • 1998-07-01 JP JP11506537A patent/JP2000511111A/ja active Pending
  • 1998-07-01 WO PCT/FR1998/001410 patent/WO1999001216A1/fr not_active Application Discontinuation
  • 1998-07-01 CA CA002295850A patent/CA2295850A1/fr not_active Abandoned
  • 1998-07-01 EP EP98935077A patent/EP0994749A1/de not_active Withdrawn
  • 1998-07-01 CN CN98807865A patent/CN1124885C/zh not_active Expired - Fee Related
  • 1998-07-01 US US09/446,955 patent/US6491886B1/en not_active Expired - Fee Related
  • 1998-07-01 KR KR1020007000009A patent/KR100351601B1/ko not_active IP Right Cessation
  • 1998-07-01 AU AU84453/98A patent/AU8445398A/en not_active Abandoned
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