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
  • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
  • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/56—Platinum group metals
  • B01J23/63—Platinum group metals with rare earths or actinides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • 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
  • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
• • 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
  • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
  • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
• • 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
  • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • 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
  • B01J35/613—10-100 m2/g
• • 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
  • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
  • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
• • 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
  • B01J37/03—Precipitation; Co-precipitation
  • B01J37/031—Precipitation
• • 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
  • B01D2255/1023—Palladium
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/20—Metals or compounds thereof
  • B01D2255/207—Transition metals
  • B01D2255/20715—Zirconium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2258/00—Sources of waste gases
  • B01D2258/01—Engine exhaust gases
  • B01D2258/012—Diesel engines and lean burn gasoline engines
• • 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
  • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
• • 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
  • 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 the treatment of exhaust gases emitted by combustion engines, including those fitted to motor vehicles, and particularly compression ignition engines called diesel engines. More specifically, the invention relates to a catalytic converter for the treatment of these exhaust gases, an exhaust line of a motor vehicle comprising such a converter and a method of manufacturing this catalytic converter.
• Modern vehicles are equipped with different means to treat the exhaust and minimize air pollution due to carbon monoxide releases, nitrogen oxides and unburned hydrocarbons.
• These means figures a large number of catalytic converters.
• catalytic converters are said to be multifunctional when they eliminate the three main types of pollutants mentioned above. They are called oxidation when they essentially make it possible to transform unburned hydrocarbons and carbon monoxide into carbon dioxide. As a rule, they comprise a substrate on which is deposited a catalytic coating comprising one or more precious metals associated with one or more additional metals such as iron, nickel, zirconium, vanadium, chromium or cerium.
• the substrate is typically an inert and rigid structure, also called monolith, usually ceramic or metal and forming a series of channels or ducts, for example in a honeycomb form.
• European Patent EP-27069 discloses a catalyst comprising a refractory oxide-based support and whose active catalytic phase. is composed of cerium, iron and at least one metal taken from the group consisting of iridium and rhodium, and a metal taken from the platinum and palladium group.
• EP-54472 describes a multifunctional catalyst comprising an inert honeycomb substrate coated with a layer or film of refractory oxide, the active phase being made of copper, cerium or iron of at least one metal selected from the group comprising platinum or palladium and at least one metal selected from the group consisting of iridium and rhodium.
• the active phase is deposited or impregnated uniformly on the surface of the monolithic support, by total immersion of the support in a precursor solution of the elements of the active phase.
• compositions based on zirconium oxide or cerium are considered to be among the most promising for the treatment of exhaust gases from motor vehicles or the like.
• catalytic converters are effective only below a reference temperature, which varies according to the composition used. As a result, a great deal of work is aimed at accelerating the temperature rise of the elements of the exhaust line, in particular following a cold start.
• a catalytic system for the treatment of exhaust gas of an internal combustion engine comprising palladium dispersed by a support based on zirconium oxide ZrO 2 , and praseodymium oxide Pr 6 O, in a mass ratio between the zirconium oxide and praseodymium of between 5 and 20%.
• the weight ratio is more particularly between 10 and 15%, and preferably close to 12%, ie a support whose raw formulation is written Zr 0 92Pr 0 OsO 2 -O, ⁇ corresponding to about 0.01 (and which can be calculated by recalling that the support is a mixture of ZrO 2 and Pr 6 On). Good results have been obtained with a support whose specific surface is of the order of 50 m 2 g -1 .
• the palladium impregnation may be carried out in such a way that its mass concentration (relative to the support) is at most 1.5%, preferably at most 1% and preferably still close to 0.8%. %, that is to say a relatively low content, leading to a reduction in cost.
• the catalytic system according to the invention is particularly suitable for the treatment of exhaust gas whose temperature is between 120 ° C and 400 0 C, and more particularly those whose carbon monoxide concentration is between 2000 and 5000 ppm, ie exhaust gases that are characterized by both a low temperature and a relatively high concentration of carbon monoxide.
• Figure 5 a comparative curve of the conversion rates as a function of the temperature of the gases, depending on the concentration of palladium, for different media.
• Catalyst compositions based on predominant zirconium oxide and a rare earth oxide of the group of lanthanides, chosen from praseodymium, lanthanum and neodymium, are known from French Patent 2,866,871. This document notably describes in its example 2, a composition comprising 85% of zirconium and 15% of praseodymium (proportions expressed as mass percentages of the ZrO 2 and Pr 6 On oxides).
• this composition is prepared by introducing into a beaker, with stirring, 708 ml of zirconium nitrate (in solution at 120 g / l) and 30 ml of praseodymium nitrate (in solution). at 500 g / l), and supplementing with distilled water to form a liter of nitrate solution.
• This nitrated solution is introduced in one hour into a reactor with constant stirring in which a solution comprising 220 ml of ammonia has also been prepared.
• the solution is placed under an autoclave to be heated at 150 ° C for hours, then filtered to recover a precipitate.
• An ammonium laurate gel is prepared by introducing 250 g of lauric acid into 135 ml of ammonia 12 mol / l and 500 ml of distilled water. 21.4 g of gel are added to 100 g of precipitate and after mixing, the assembly is heated at 500 ° C. for 4 hours in steps. After a calcination of 4 hours at 900 ° C., an oxide is obtained whose specific surface area is 63 m 2 / g, and 41 m 2 / g for calcination at 1000 ° C. for 10 hours.
• oxide-based catalyst supports an Al 2 O 3 alumina support, a CeO 2 ceria support, a mixed alumina-ceria Ce 0 2 cerium oxide carrier. 50Zr 0 50O 2 , a support based on a mixed oxide of the formula (ZrO 2 ) 0 7125 (CeO 2 ) O 2 -17 (Nd 2 O 3 ) o o 5 (La 2 O 3 ) o 0205, which thereafter will be simply referenced by the expression "MO”, and a support
• the alumina support has a surface area of about 144 m 2 g -1 , all other supports have a specific surface area of about 50 m 2 g -1 .
• Each support is subjected to calcination at 800 0 C for 12 hours to stabilize the material before impregnation with a noble metal, impregnation carried out using nitrate salts as precursors.
• concentrations measured by elemental analysis, were obtained:
• each catalyst thus formed is subjected to a hydrothermal treatment at 700 ° C. to simulate the aging of the catalyst, each sample being subjected to an air passage. hot saturated with water.
• Powdered catalysts are then compressed to form supports and activated by heating at 400 ° C. for 30 minutes, under an 8% oxygen flow in argon.
• a reference gas comprising 0.1% CO, 300 ppm NO, 10% CO 2 , 200 ppm H 2 , 100 ppm decane, 8% O 2 , 1% H 2 O and 100 ppm was prepared.
• a 50/50 propane / propene mixture Argon is used as the carrier gas and the catalysts are exposed to this reference gas, each time for 20 minutes, at temperatures of 100 ° C., 125 ° C., 150 ° C., 200 ° C. and 25 ° C., respectively.
• Figures 1 and 2 show the conversion rates of carbon monoxide as a function of temperature.
• the square marks correspond to praseodymium supports, triangular markings to alumina supports, crosses to ceria-zirconium oxides and MO oxide stars.
• the classification of the supports is modified, the praseodymium support obtaining a conversion rate of the order of 95% for a temperature of 400 0 C.
• Figures 3 and 4 show the results with respect to hydrocarbon conversion rates. The same marks were used for the different media. It can be seen that the supports are much less differentiated, with the exception of the alumina support, which appears to be less efficient. In any case, the catalyst comprising praseodymium leads to quite acceptable performance.
• the tests reported in FIG. 1 were repeated, but this time by comparing catalysts carrying respectively 0.8% (solid lines) or 2% (discontinuous lines) of palladium.
• the first two curves concern the supported catalyst containing praseodymium (square marks), the two central curves (triangular marks), a support of alumina and the two right curves (round marks), an OM support.
• the support containing praseodymium the measured performances are higher in the case of the catalyst having only 0.8% of palladium, the conversion rate at 100% being even obtained about 100 0 C lower.
• the catalyst according to the invention is therefore remarkable in that it makes it possible to use reduced levels of palladium, without degrading performance (and in fact by increasing them), and with very good conversion rates at low levels. temperatures, which is particularly suitable

Landscapes

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=40154937

Family Applications (1)

Country Status (3)

Family Cites Families (4)

• 2008
  • 2008-05-27 FR FR0853446A patent/FR2931700B1/fr not_active Expired - Fee Related
• 2009
  • 2009-05-25 EP EP09753859A patent/EP2288429A1/de not_active Withdrawn
  • 2009-05-25 WO PCT/EP2009/056323 patent/WO2009144204A1/fr active Application Filing

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events