WO2018224946A1 - Nouveau composé de type pérovskite pour des applications de gaz d'échappement d'essence - Google Patents

Nouveau composé de type pérovskite pour des applications de gaz d'échappement d'essence Download PDF

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WO2018224946A1
WO2018224946A1 PCT/IB2018/053987 IB2018053987W WO2018224946A1 WO 2018224946 A1 WO2018224946 A1 WO 2018224946A1 IB 2018053987 W IB2018053987 W IB 2018053987W WO 2018224946 A1 WO2018224946 A1 WO 2018224946A1
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composition
formula
compound
catalyst
periodic table
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Kerry SIMMANCE
David Thompsett
Weiliang Wang
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Johnson Matthey Public Limited Company
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • 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
    • 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
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    • 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
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    • 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
    • B01J23/78—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 alkali- or alkaline earth metals
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    • 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
    • B01J23/83—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 rare earths or actinides
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    • 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
    • B01J23/889—Manganese, technetium or rhenium
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    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/393—Metal or metal oxide crystallite size
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    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
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    • B01J35/613—10-100 m2/g
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/082—Decomposition and pyrolysis
    • B01J37/086—Decomposition of an organometallic compound, a metal complex or a metal salt of a carboxylic acid
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/349—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of flames, plasmas or lasers
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    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the invention relates to a novel perovskite-type composition, its novel synthesis, its use as a three-way catalyst (TWC) in exhaust systems for internal combustion engines, and a method for treating an exhaust gas from an internal combustion engine.
  • TWC three-way catalyst
  • TWC turbine-to-fuel combustion engines
  • HCs hydrocarbons
  • CO carbon monoxide
  • NOx nitrogen oxides
  • Emission control systems including exhaust gas catalysts, are widely utilized to reduce the amount of these pollutants emitted to atmosphere.
  • a commonly used catalyst for gasoline engine applications is the TWC.
  • TWCs perform three main functions: (1) oxidation of carbon monoxide (CO); (2) oxidation of unburnt hydrocarbons; and (3) reduction of NOx to N 2 .
  • TWCs that usually consist of Platinum Group Metals (PGMs) dispersed over high surface area alumina and ceria-zirconia supports, were first introduced in the early 1980s for gasoline engine aftertreatment. With the need to meet increasingly more stringent emission limits, identifying alternative catalyst compositions which utilise either lower or no PGMs remains an active research topic.
  • PGMs Platinum Group Metals
  • ABO3 Perovskite-type oxides
  • One aspect of the present disclosure is directed to a composition
  • a composition comprising a perovskite type compound of formula (I): Ax- y A' y Bi-zB'z03; wherein A is an ion of a metal of group 3 of the periodic table of elements; wherein A' is an ion of a metal of group 2 or 10, 11, or 13 of the periodic table of elements; wherein x is from 0.7 to 1; wherein y is from 0 to 0.5; wherein z is from 0 to 0.5; and wherein specific surface area of the compound of formula (I) is at least 20 m 2 /g.
  • a second aspect of the present disclosure is directed to a composition
  • a composition comprising a perovskite type compound of formula (II): Ax-yA'yFei zB'zC ; wherein A is an ion of a metal of group 3 of the periodic table of elements; wherein A' is an ion of a metal of group 2 or 3 of the periodic table of elements; wherein B' is an ion of metal of groups 7, 8, 9, 10,
  • a third aspect of the present disclosure is directed to a process of making a composition comprising a compound of formula (I): Ax-yA'yBi-zB'zC , comprising (a) mixing suitable precursors with suitable solvents to form a mixture, (b) passing the mixture through a flame reactor, and (c) collecting the compound of formula (I); wherein A is an ion of a metal of group 3 of the periodic table of elements; wherein A' is an ion of a metal of group 2 or 3 of the periodic table of elements; wherein B and B' are ions of metal of groups 7, 8, 9, 10, 11, or 13 of the periodic table of elements; wherein x is from 0.7 to 1; wherein y is from 0 to 0.5; wherein z is from 0 to 0.5; and wherein specific surface area of the compound of formula (I) is at least 20 m 2 /g.
  • a fourth aspect of the present disclosure is directed to a three-way catalyst comprising a composition comprising a perovskite type compound of formula (I), as described in the first aspect.
  • a fifth aspect of the present disclosure is directed to a three-way catalyst comprising a composition comprising a perovskite type compound of formula (II), as described in the second aspect.
  • the invention also encompasses an exhaust system for internal combustion engines that comprises the three-way catalyst component of the invention.
  • the invention also encompasses treating an exhaust gas from an internal combustion engine, in particular for treating exhaust gas from a gasoline engine.
  • the method comprises contacting the exhaust gas with the three-way catalyst component of the invention.
  • FIG. 1 shows an illustration of Flame Spray Pyrolysis (FSP).
  • FIG. 2a shows a TEM image of Catalyst 1A, highlighting the spherical morphology with appropriate lattice fringe analysis/planes shown
  • FIG. 2b shows a TEM image of Catalyst 1A with evidence of amorphous/disordered surfaces and the crystalline core/bulk
  • FIG. 2c shows a TEM image of Catalyst 1 A, highlighting how the primary nanoparticles can agglomerate to form larger particles.
  • FIG. 6 shows XRD pattern of LaFe03 (comparative Catalyst IK) synthesized by conventional classic citrate methods.
  • FIG. 7 shows XRD pattern of LaFe03 (comparative Catalyst 1L) synthesized by conventional ballmilled solid state routes.
  • FIG. 8a shows the CO conversion under steady state stoic conditions for Catalysts 3A-3F of the present invention
  • FIG. 8b shows the NO conversion under steady state stoic conditions for Catalysts 3A-3F of the present invention
  • FIG. 4c shows C3H6 conversion under steady state stoic conditions for Catalyst 3A-3F of the present invention.
  • One aspect of the present disclosure is directed to a composition
  • a composition comprising a perovskite type compound of formula (I): Ax-yA' y Bi-zB'z03; wherein A is an ion of a metal of group 3 of the periodic table of elements; wherein A' is an ion of a metal of group 2 or 3 of the periodic table of elements; wherein B and B' are ions of metal of groups 7, 8, 9, 10, 11, or 13 of the periodic table of elements; wherein x is from 0.7 to 1; wherein y is from 0 to 0.5; wherein z is from 0 to 0.5; and wherein specific surface area of the compound of formula (I) is at least 20 m 2 /g.
  • a of the compound of formula (I) can be Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, or Gd.
  • A is La, Y, Sr; most preferably, A is La.
  • A' of the compound of formula (I) can be Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Nd, or Gd. In preferred embodiments, A' is Sr, Ca, Y, or Ce.
  • B of the compound of formula (I) can be Mn, Co, Fe, Ni, Cr, Ti, Zr, Al, or Ga.
  • B is Mn, Co, Fe, or Ni; more preferably, B is Mn or Fe; most preferably, B is Fe.
  • B' of the compound of formula (I) can be Cu, Mn, Co, Fe, Ni, Cr, Ti, Zr, Al, or Ga. In preferred embodiments, B' is Al, Fe, Co, Mn, or Cu; more preferably, B' is Cu or Fe. In the compound of formula (I), x can be 0.8-1, 0.9-1, 0.7-0.9, or 0.7-0.8.
  • y can be 0-0.4, 0-0.3, 0-0.2, or 0-0.1.
  • z can be 0-0.5, 0-0.4, 0-0.3, 0-0.2, or 0-0.1. In some embodiments, z is 0.
  • the specific surface area of the compound of formula (I) can be at least 30 m 2 /g, at least 40 m 2 /g, at least 50 m 2 /g, or at least 60 m 2 /g.
  • the compound of formula (I) can have a mean primary crystal size of less than 60 nm. In some preferred embodiments, the compound of formula (I) has a mean primary crystal size of less than 30, 25, 20, 15, 10, or 5 nm. In other preferred embodiments, the compound of formula (I) has a mean primary crystal size of 5 nm-60 nm, 5 nm-50 nm, 5 nm-40 nm, 5 nm-30 nm or 5 nm-20 nm.
  • the compound of formula (I) can be at least 90% phase pure. It is more preferred to be at least 95%, 96%, 97%, 98% or 99% phase pure.
  • percent in connection with the perovskite materials means:
  • the compound of formula (I) can be prepared by Flame Spray Pyrolysis (FSP) (e.g., see FIG. 1).
  • FSP Flame Spray Pyrolysis
  • soluble precursors in organic solvents are combusted in a CH4/O2 flame to directly give nano-crystalline particles.
  • the compound of formula (I) can have a primary particle morphology of spherical shape. (E.g., see FIG. 2a).
  • the compound of formula (I) can have a disordered surface as evidenced by TEM. ⁇ Kg., see FIG. 2b).
  • the compound of formula (I) can have a surface composition range of ( ⁇ + ⁇ ')/( ⁇ + ⁇ ') between 0.5 and 3.0, preferably between 0.5 and 2.0, measured by XPS.
  • the surface composition ranges of ( ⁇ + ⁇ ')/( ⁇ + ⁇ ') can also be from 0.5 to 1.5, 0.5 to 1.0,
  • Perovskites prepared by FSP can have an average primary particle size ranging between 5 and 20 nm with a primary particle morphology of spherical shape as highlighted in the TEM images (FIGs. 2a-2c) for a LaFeC based perovskite.
  • the crystallite size as calculated from XRD also agrees with the primary particle size observed by TEM.
  • the nano-crystalline material has a somewhat disordered/amorphous-like surface as evidenced by TEM (FIG. 2b), which may enhance its activity for TWC by allowing for more oxygen vacancies to be created at the surface and/or a higher concentration of active B site cations at the surface.
  • the primary nanoparticles agglomerate to form larger particles which can be of micron size in their powder form but still retain a high surface area (e.g., >40 m 2 g _1 ).
  • the high surface area allows for: a higher concentration of active B cations to be present at the surface as evidenced by XPS, a higher concentration of surface oxygen vacancies as evidenced by O2-TPD, and improved reducibility of the B cation at temperatures below 500°C as evidenced by H2-TPR.
  • phase purity of the compound of formula (I) is also important for optimum activity; the presence of other crystalline phases, such as La(OH)3, La 2 C , Fe 2 03 etc., results in lower activity.
  • a perovskite prepared by FSP can have a primary particle morphology of spherical shape with a size ranging from 5 - 60 nm, preferably from 5-30 nm, which may aggregate but retain a high surface area above 40 m 2 g _1 and have a disordered surface.
  • a second aspect of the present disclosure is directed to a composition
  • a composition comprising a perovskite type compound of formula (II): Ax-yA'yFei-zB'zCb; wherein A is an ion of a metal of group 3 of the periodic table of elements; wherein A' is an ion of a metal of group 2 or 3 of the periodic table of elements; wherein B' is an ion of metal of groups 7, 8, 9, 10,
  • a site deficient perovskites e.g., Lai xFeC
  • a site deficient perovskites can have a higher concentration of B site cations at the surface, as evidenced by XPS; can have more reducible B site cations, as evidenced by H2-TPR; and/or can have a higher OSC.
  • a of the compound of formula (II) can be Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, or Gd.
  • A is La, Y, Sr; most preferably, A is La.
  • A' of the compound of formula (II) can be Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Nd, or Gd. In preferred embodiments, A' is Sr, Ca, Y, or Ce.
  • B' of the compound of formula (II) can be Cu, Mn, Co, Ni, Cr, Ti, Zr, Al or Ga.
  • B' is Al, Co, Mn, or Cu; more preferably, B' is Cu.
  • y can be 0-0.4, 0-0.3, 0-0.2, or 0-0.1. In some embodiments, y is 0.
  • z can be 0-0.5, 0-0.4, 0-0.3, 0-0.2, or 0-0.1. In some embodiments, z is 0.
  • the specific surface area of the compound of formula (II) can be at least 30 m 2 /g, at least 40 m 2 /g, at least 50 m 2 /g, or at least 60 m 2 /g.
  • the compound of formula (II) can have a mean primary crystal size of less than 60 nm. In some preferred embodiments, the compound of formula (II) has a mean primary crystal size of less than 30, 25, 20, 15, 10, or 5 nm. In other preferred embodiments, the compound of formula (II) has a mean primary crystal size of 5 nm-60 nm, 5 nm-50 nm, 5 nm-40 nm, 5 nm-30 nm, or 5 nm-20 nm.
  • the compound of formula (II) can be at least 90% phase pure. It is more preferred to be at least 95%, 96%, 97%, 98% or 99% phase pure.
  • the compound of formula (II) can be substantially free of crystalline iron oxides (e.g., Fe2C ).
  • the expression “substantially free of as used herein with reference to a material, means that the material in a minor amount, such as ⁇ 10 % or ⁇ 5 % by weight, preferably ⁇ 2 % by weight, more preferably ⁇ 1 % by weight.
  • the compound of formula (II) of the present invention can be substantially free of crystalline Fe2C , even when the deficiency is more than 0.05 (i.e., x ⁇ 0.95).
  • the compound of formula (II) can have a primary particle morphology of spherical shape. (E.g., see FIG. 2a).
  • the compound of formula (II) can be prepared by FSP.
  • the compound of formula (II) can have a disordered surface as evidenced by TEM. (E.g., see FIG. 2b). Disorder can be amorphous in some embodiments, or it can be lack of long range order in other embodiments.
  • the compound of formula (II) can have a surface composition range of ( ⁇ + ⁇ ')/( ⁇ + ⁇ ') between 0.5 and 3.0, preferably between 0.5 and 2.0, measured by XPS.
  • the surface composition ranges of ( ⁇ + ⁇ ')/( ⁇ + ⁇ ') can also be from 0.5 to 1.5, 0.5 to 1.0, 1.0 to 2.0, or 1.0 to 1.5.
  • Perovskites prepared by FSP can have an average primary particle size ranging between 5 and 20 nm with a primary particle morphology of spherical shape as highlighted in the TEM images (FIGs. 2a-2c) for a LaFeC based perovskite.
  • the crystallite size as calculated from XRD also agrees with the primary particle size observed by TEM.
  • the nano-crystalline material has a somewhat disordered/amorphous-like surface as evidenced by TEM (FIG. 2b), which may enhance its activity for TWC by allowing for more oxygen vacancies to be created at the surface and/or a higher concentration of active B site cations at the surface.
  • the primary nanoparticles agglomerate to form larger particles which can be of micron size in their powder form but still retain a high surface area (e.g., >40 m 2 g _1 ).
  • the high surface area allows for: a higher concentration of active B cations to be present at the surface as evidenced by XPS, a higher concentration of surface oxygen vacancies as evidenced by O2-TPD, and improved reducibility of the B cation at temperatures below 500°C as evidenced by H2-TPR.
  • phase purity of the compound of formula (II) is also important for optimum activity; the presence of other crystalline phases, such as La(OH)3, La 2 C , Fe 2 03 etc., results in lower activity.
  • a perovskite prepared by FSP can have a primary particle morphology of spherical shape with a size ranging from 5 - 60 nm, preferably from 5-30 nm, which may aggregate but retain a high surface area above 40 m 2 g _1 and have a disordered surface.
  • a third aspect of the present disclosure is directed to a process of making a composition comprising a compound of formula (I): Ax-yA'yBi-zB'zC , comprising (a) mixing suitable precursors with suitable solvents to form a mixture, (b) passing the mixture through a flame reactor, and (c) collecting the compound of formula (I); wherein A is an ion of a metal of group 3 of the periodic table of elements; wherein A' is an ion of a metal of group 2 or 3 of the periodic table of elements; wherein B and B' are ions of metal of groups 7, 8, 9, 10, 11, or 13 of the periodic table of elements; wherein x is from 0.7 to 1; wherein y is from 0 to 0.5; wherein z is from 0 to 0.5; and wherein specific surface area of the compound of formula (I) is at least 20 m 2 /g.
  • a of the compound of formula (I) can be Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, or Gd.
  • A is La, Y, Sr; most preferably, A is La.
  • A' of the compound of formula (I) can be Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Nd, or Gd. In preferred embodiments, A' is Sr, Ca, Y, or Ce.
  • B of the compound of formula (I) can be Mn, Co, Fe, Ni, Cr, Ti, Zr, Al or Ga.
  • B is Mn, Co, Fe or Ni; more preferably, B is Mn or Fe; most preferably, B is Fe.
  • B' of the compound of formula (I) can be Cu, Mn, Co, Fe, Ni, Cr, Ti, Zr, Al or Ga.
  • B' is Al, Fe, Co, Mn, or Cu; more preferably, B' is Cu or Fe.
  • x can be 0.8-1, 0.9-1, 0.7-0.9, or 0.7-0.8.
  • y can be 0-0.4, 0-0.3, 0-0.2, or 0-0.1.
  • z can be 0-0.5, 0-0.4, 0-0.3, 0-0.2, or 0-0.1. In some embodiments, z is 0.
  • the specific surface area of the compound of formula (I) can be at least 30 m 2 /g, at least 40 m 2 /g, at least 50 m 2 /g, or at least 60 m 2 /g.
  • the compound of formula (I) can have a mean crystal size of less than 60 nm. In some preferred embodiments, the compound of formula (I) has a mean crystal size of less than 30, 25, 20, 15, 10, or 5 nm. In other preferred embodiments, the compound of formula (I) has a mean primary crystal size of 5 nm-60 nm, 5 nm-50 nm, 5 nm-40 nm, 5 nm-30 nm, or 5 nm-20 nm.
  • the compound of formula (I) can be at least 90% phase pure. It is more preferred to be at least 95%, 96%, 97%, 98% or 99% phase pure.
  • the compound of formula (I) can have a primary particle morphology of spherical shape.
  • the compound of formula (I) can have a disordered surface as evidenced by TEM.
  • the compound of formula (I) can have a surface composition range of ( ⁇ + ⁇ ')/( ⁇ + ⁇ ') between 0.5 and 3.0, preferably between 0.5 and 2.0, measured by XPS.
  • the surface composition ranges of ( ⁇ + ⁇ ')/( ⁇ + ⁇ ') can also be from 0.5 to 1.5, 0.5 to 1.0, 1.0 to 2.0, or 1.0 to 1.5.
  • the suitable precursors can be metal precursors that are decomposed under flame, for example, lanthanum(III) 2-ethylhexanoate (solid or solution), lanthanum(III) acetylacetonate hydrate, lanthanum 2,4-pentanedionate, yttrium(III) 2-ethylhexanoate, yttrium(III) acetylacetonate hydrate, cerium(III) 2-ethylhexanoate (also known as cerium octanoate), cerium(III) nitrate, cerium(III) carbonate, cerium(III) acetate, strontium(II) 2- ethylhexanoate, strontium(II) acetate hemihydrate, calcium(II) 2-ethylhexanoate, calcium(II) acetate, iron(II) naphthenate, iron(III) acetylacetonate, cobal
  • Suitable solvent can be any solvent that can move (or carry) the suitable precursors.
  • the suitable solvent is an organic solvent or a mixture of organic solvent and acid. More preferably, the suitable solvent can dissolve at least 40%, 50%, 60%, 70%, 80%, or 90% of the suitable precursors.
  • the suitable solvent and/or acid include, but are not limited to, carboxylic acids (propionic acid, 2-ethylhexanoic acid, acetic acid) and alcohol, polar (THF, acetonitrile and solvents from the glycol family) and non-polar solvents (xylene, toluene) or any combination thereof.
  • the mixture is a solution.
  • the molar concentration of the solution can be 0.05 to 2.5 mol/L, preferably, 0.1-2.0 mol/L, more preferably, 0.2-1.5 mol/L or 0.2- 1.0 mol/L, most preferably, 0.25-0.6 mol/L.
  • the mixture can be introduced into the flame reactor via a nozzle. It is preferred that the mixture is sprayed into the flame reactor via the nozzle.
  • the feed rate can be 1 to 20 mL/min, more preferably 5 to 10 mL/min.
  • the O2 dispersion flow and the O2 sheath flow can be 2 to 50 L/min, more preferably 5 to 20 L/min.
  • the flame reactor comprises a suitable burner with a suitable flame source.
  • the suitable flame source can be CH4/O2, H2/O2, acetylene/02, and propane/02.
  • the flow rate can be 1 to 3 L/min of fuel and 2 to 5 L/min of oxidant.
  • the suitable solvent can be evaporated, and the suitable precursors can be combusted to form the compound of formula (I).
  • a quartz shield may also be used, which can raise the flame temperature (e.g., via limiting the air entrainment) and/or increase residency time. Length of the quartz shield ranging from 5-50 cm, preferably, 10-40 cm, more preferably, 15 to 30 cm. As the consequence, the materials tend to give rise to particles with larger crystallite and aggregate size while making them thermally more stable. For example, see Catalysts 1 A-l , 1 A-2, and 1A-3.
  • the process of the present invention can be a process called Flame Spray Pyrolysis (FSP) (e.g., see FIG. 1).
  • FSP can be a combustion method in which soluble precursors in organic solvents are combusted in a CH4/O2 flame to directly give nano- crystalline particles.
  • a fourth aspect of the present disclosure is directed to a three-way catalyst comprising a composition comprising the perovskite type compound of formula (I): A x - yA'yBi-zB'zC , as described in the first aspect of the present disclosure.
  • a fifth aspect of the present disclosure is directed to a three-way catalyst comprising a composition comprising the perovskite type compound of formula (II): A x - yA'yFei-zB'zC , as described in the second aspect of the present disclosure.
  • the three-way catalysts of the present invention have been evaluated for their TWC activity under simulated gasoline exhaust feeds and their oxygen storage properties (E.g. , see Example 2, FIGs. 4a-4c and 5a-5b).
  • FSP made perovskites have improved CO, HC and NO light-off performance under our simulated gasoline exhaust conditions which results in higher CO, HC and NO conversions at standard operating conditions between 400-500°C.
  • the perovskite compounds of the present invention have improved oxygen storage capacity (OSC) properties, this is the case for both the total and dynamic OSC which can be as much as more than 3 times greater between 250 and 450°C.
  • OSC oxygen storage capacity
  • the improvement in surface area also results in the synthesis of the perovskite compound of the present invention, which is more reducible as evidenced by H2-TPR; for example, with Fe based perovskites, a higher amount of reducible Fe(III) is evidenced below 450°C for the perovskite compound of the present invention, compared to those synthesized with traditional methods.
  • the invention also encompasses an exhaust system for internal combustion engines that comprises the three-way catalyst component of the invention.
  • the three-way catalyst component may be placed in a close-coupled position or in the underfloor position.
  • the invention also encompasses treating an exhaust gas from an internal combustion engine, in particular for treating exhaust gas from a gasoline engine.
  • the method comprises contacting the exhaust gas with the three-way catalyst component of the invention.
  • Powder X-ray diffraction (PXRD) patterns were collected on a Bruker D8 powder diffractometer using a CuKa radiation (40-45 kV, 40 mA) at a step size of 0.04° and a 1 s per step between 5° and 100° (2 ⁇ ).
  • Transmission electron microscopy (TEM) images were obtained on a JEM 2800 (Scanning) TEM with 200 kV Voltage. The micropore volume and surface area were measured using N2 at 77 K on a 3Flex surface characterization analyzer (Micromeritics).
  • Lanthanum(III) 2-ethylhexanoate solution (Molekular), lanthanum(III) 2- ethylhexanoate solid (American Element), strontium(II) 2-ethylhexanoate (Alfa, 40% in 2- ethylhexanoic acid), strontium(II) acetate hemihydrate (Alfa), cerium(III) 2- ethylhexanoate (Alfa, 49% in 2-ethylhexanoic acid), calcium(II) 2-ethylhexanoate (Alfa, 98%), yttrium(III) 2-ethylhexanoate (Alfa, 99.8%), iron(II) naphthenate (80% in mineral spirits, Alfa), iron(III) acetylacetonate (Alfa), copper(II) acetate anhydrous (Alfa, 98%),
  • a FSP perovskite material is typically synthesized by liquid feed flame pyrolysis.
  • the precursors are dissolved in a suitable solvent at a specific temperature.
  • the solution is then fed with an oxygen stream into a flame.
  • the particles are conveyed through stainless steel ducting to a bag house with air filter bag and recovered by back-pulsing the filter bag.
  • Catalyst 1A (Lao.sFeC ): Lanthanum(III) 2-ethylhexanoate solution (27.78g, 0.02mole) and iron(III) acetylacetonate (8.84g, 0.025mole) were dissolved in 150mL of xylene. The solution (200mL, 0.33mol/L) was then fed with an oxygen stream (dispersion and sheath flow rate 20L/min) into a CH4/O2 flame (1.5/3.2 L/min mix) at a rate of lOmL/min. The particles were conveyed through stainless steel ducting to a bag house with air filter bag (Whatman GF/D filter papers) and recovered by back-pulsing the filter bag.
  • Lanthanum(III) 2-ethylhexanoate solution 27.78g, 0.02mole
  • iron(III) acetylacetonate (8.84g, 0.025mole) were dissolved in 150mL of
  • Catalyst 1A was phase pure with an average crystallite size of 12 nm as evidenced by XRD.
  • FIGs. 2a-2c For Catalyst 1A.
  • the crystallite size as calculated from XRD was consistent with the primary particle size observed by TEM.
  • the nano-crystalline material had a somewhat disordered/amorphous-like surface as evidenced by TEM (FIG. 2b), which may enhance its activity for TWC by allowing for more oxygen vacancies to be created at the surface and/or a higher concentration of active B site cations at the surface.
  • the primary nanoparticles agglomerate to form larger particles which can be of micron size in their powder form but still retain a high surface area (e.g., >40 m 2 g _1 ).
  • the high surface area allows for: a higher concentration of active B cations to be present at the surface as evidenced by XPS, a higher concentration of surface oxygen vacancies as evidenced by O2-TPD and improved reducibility of the B cation at temperatures below 500°C as evidenced by H2-TPR.
  • phase purity (e.g., >90%) of the catalyst of the present invention is also important for optimum activity; the presence of other crystalline phases such as La(OH)3, La2C , Fe2C etc., results in lower activity.
  • a perovskite prepared by FSP would have a primary particle morphology of spherical shape with a size ranging from 5 - 60 nm, preferably from 5-30 nm, which may aggregate but retain a high surface area above 40 m 2 g _1 and have a disordered surface.
  • Catalysts lA-1, 1A-2, and 1A-3 were synthesized without quartz tube, or with different length of quartz tube respectfully. These catalysts were prepared with slightly different process conditions; the solution (lOOmL, 0.33mol/L) was fed with an oxygen stream (dispersion and sheath flow rate 5 L/min) into a CH4/O2 flame (1.5/3.2 L/min mix) at a rate of 5mL/min. The results are summarized in Table 1.
  • Catalyst IB (Lao sYoJeC
  • Lanthanum(III) 2-ethylhexanoate solution 38.58g, 0.02mole
  • yttrium(III) 2- ethylhexanoate (3.89g, 0.005mole) and iron(III) acetylacetonate 13.26g, 0.025mole
  • the solution 225mL, 0.33mol/L
  • Catalyst IB was phase pure with an average crystallite size of 10 nm as evidenced by XRD.
  • Catalyst 1C (Lao.sCaoJeC ):
  • Catalyst 1C was phase pure with an average crystallite size of 10 nm as evidenced by XRD.
  • Catalyst ID (Lao.sSroJeC ): Lanthanum(III) 2-ethylhexanoate solution (38.58g, 0.02mole), strontium(II) 2- ethylhexanoate (40% in 2-ethylhexanoic acid) (6.92g, 0.005mole) and iron(III) acetylacetonate (13.26g, 0.025mole) were dissolved in 180mL of xylene.
  • the solution (225mL, 0.33mol/L) was then fed with an oxygen stream (dispersion and sheath flow rate 5L/min) into a CH4/O2 flame (1.5/3.2 L/min mix) at a rate of 5mL/min.
  • the particles were conveyed through stainless steel ducting to a bag house with air filter bag (Whatman GF/D filter papers) and recovered by back-pulsing the filter bag.
  • the resulting Catalyst ID was phase pure with an average crystallite size of 9 nm as evidenced by XRD.
  • Catalyst IE (LaFeo.8Cuo.2O3):
  • copper(II) acetate (1.37g, 0.005mole) and iron(III) acetylacetonate (10.61g, 0.02mole) were dissolved in 180mL of a 1 : 1 mixture of ethanol and 2-ethylhexanoic acid.
  • the resulting solution (28.40g) containing a mixture of copper(II) 2-ethylhexanoate (0.005moles) and iron(III) 2-ethylhexanoate (50% cone, 0.02 moles) was mixed with lanthanum(III) 2-ethylhexanoate solution (38.58g, 0.02mole) and 180mL of xylene.
  • the solution (225mL, 0.33mol/L) was then fed with an oxygen stream (dispersion and sheath flow rate 5L/min) into a CH4/O2 flame (1.5/3.2 L/min mix) at a rate of 5mL/min.
  • the particles were conveyed through stainless steel ducting to a bag house with air filter bag (Whatman GF/D filter papers) and recovered by back-pulsing the filter bag.
  • the resulting Catalyst IE was phase pure with an average crystallite size of 12 nm as evidenced by XRD.
  • Catalyst IE had a specific surface area of 47 m 2 g _1 with spherical particle morphology,
  • the particles were conveyed through stainless steel ducting to a bag house with air filter bag (Whatman GF/D filter papers) and recovered by back-pulsing the filter bag.
  • Catalyst IF was phase pure with an average crystallite size of 11 nm as evidenced by XRD.
  • Catalyst 1G (Lao.gSro.iFeC ):
  • Lanthanum(III) 2-ethylhexanoate solution (31.25g, 0.0225mole), strontium(II) 2- ethylhexanoate (40% in 2-ethylhexanoic acid) (2.31g, 0.0025mole) and iron(II) naphthenate (80% in mineral spirits) (11.57g, 0.025mole) were dissolved in lOOmL of xylene.
  • the solution (150mL, 0.5mol/L) was then fed with an oxygen stream (dispersion and sheath flow rate 5L/min) into a CH4/O2 flame (1.5/3.2 L/min mix) at a rate of 5mL/min.
  • Catalyst 1G was 90% phase pure with an average crystallite size of 20 nm as evidenced by XRD.
  • Catalyst 1H (Lao.gSro.iFeC ):
  • Catalyst 1H was phase pure with an average crystallite size of 9 nm as evidenced by XRD.
  • Catalyst II (Lao.gSro.iFeC ):
  • Catalyst II was 90% phase pure with an average crystallite size of 10 nm as evidenced by XRD.
  • the particles were conveyed through stainless steel ducting to a bag house with air filter bag (Whatman GF/D filter papers) and recovered by back-pulsing the filter bag.
  • Catalyst 1J was phase pure with an average crystallite size of 13 nm as evidenced by XRD.
  • a LaFeCb perovskite was prepared by a classic citrate route as published by Baythoun et al. [M.S.G. Baythoun, F.R. Sale, J. Mater. Sci., 17, 1982, 2757], which involves combustion of the nitrate precursors in the presence of citric acid in a 1 : 1 ratio followed by a high temperature annealing stage at either 900°C for 2-5h.
  • the resulting comparative Catalyst IK was phase pure with an average crystallite size of 100 nm as evidenced by XRD (FIG. 6).
  • These comparative Catalyst IK had specific surface areas of 15 m 2 g _1 with an undefined morphology which consisted of an open pore type network.
  • a LaFeCb perovskite was prepared by conventional ballmilling solid state routes as published by Petrovic etal. (S. Petrovic' et al, Applied Catalysis B: Environmental, 79, 2008, 186-198).
  • Lanthanum(III) acetate (6.51g) and iron(II) acetate (3.58g) were dry milled using YSZ media of size 5mm with a media to solids ratio of 10. Milling was carried out at a speed of 400rpm for 5 minutes and was repeated 20 times with a resting time of 3 minutes in between.
  • the non-perovskite product was then calcined at 700° C for 3h.
  • the resulting comparative Catalyst IL was phase pure with an average crystallite size of 30 nm as evidenced by XRD (FIG. 7).
  • EXAMPLE 2 LIGHT-OFF TESTING PROCEDURES FOR EXAMPLE 1
  • Catalysts 1A-1J were tested under a continuous gas mix with a typical TWC gas composition. The samples were tested from 110 to 500°C using a ramp rate of 10°C/min. The total flow used was 5 L/min for 0.2 g of catalyst mixed with 0.2 g of cordierite, which was placed in a fix bed reactor. The gases used and their concentrations can be found below (Table 2).
  • Catalyst 1A shows improved CO/NO light-off compared to Catalysts IB- ID and IF showing that A site deficient perovskites have an advantage over the stoichiometric compositions due to differences in the surfaces.
  • smaller A site cation dopants such as Y 3+
  • a site dopants e.g., Sr 2+
  • Catalyst IE showed an advantage over Catalyst 1A but only for CO conversion (FIG. 4a), this highlights that addition of Cu on the B site improves the oxidation function of the catalyst (including OSC performance). However, if not controlled, it can result in a lower amount of Fe at the surface, which results in poorer NO conversion.
  • the surface composition can be controlled through bulk composition effects and also through FSP process parameters, and can have a large effect on the TWC performance of the catalyst. This is highlighted in FIG. 5a and FIG. 5b.
  • Catalyst II with a higher amount of Fe at the surface results in better CO/NO conversions compared to Catalysts 1H and 1G, likewise Catalyst 1A with a higher amount of Fe at the surface results in better CO/NO conversions compared to Catalysts 1 J and IF.
  • Catalyst 3A (Lao.9Sro.1Feo.8Coo.2O3):
  • Catalyst 3 A was 90% phase pure with an average crystallite size of 9.5 nm, as evidenced by XRD.
  • Catalyst 3B (Lao.9Sro.1Feo.5Coo.5O3):
  • Catalyst 3B was phase pure with an average crystallite size of 10 nm as evidenced by XRD.
  • Catalyst 3C had a specific surface area of 46 m 2 g _1 with spherical particle morphology.
  • Catalyst 3C (Lao.gSro.iMnC ' ):
  • Catalyst 3C was phase pure with an average crystallite size of 7.6 nm, as evidenced by XRD.
  • Catalyst 3C had a specific surface area of 80 m 2 g _1 with spherical particle morphology.
  • Catalyst 3D (Lao.gSro.iCoC ' ):
  • Catalyst 3D was phase pure with an average crystallite size of 7.9 nm, as evidenced by XRD.
  • Catalyst 3D had a specific surface area of 60 m 2 g _1 with spherical particle morphology.
  • Catalyst 3E (Lao.gSro.iNiC ):
  • Catalyst 3F (Lao.9Sro.1Feo.8Mno.2O3):
  • Catalyst 3F was 90% phase pure.
  • EXAMPLE 4 LIGHT-OFF TESTING PROCEDURES FOR EXAMPLE 3

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Abstract

La présente invention concerne une composition de catalyseur à trois voies et son utilisation dans un système d'échappement pour moteurs à combustion interne. La composition de catalyseur à trois voies comprend un composé de formule (I): Ax-yA'yB1-zB'zO3; A est un ion d'un métal du groupe 3 du tableau périodique des éléments, A' un ion d'un métal du groupe 2 ou 3 du tableau périodique des éléments, B et B' des ions de métal des groupes 7, 8, 9, 10, 11, ou 13 du tableau périodique des éléments, x une valeur comprise entre 0,7 et 1; y une valeur comprise entre 0 et 0,5; z une valeur comprise entre 0 et 0,5; et la surface spécifique du composé de formule (I) étant d'au moins 20 m2/g.
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CN113365728A (zh) * 2019-03-29 2021-09-07 庄信万丰股份有限公司 在三元催化中对老化稳定的镧基钙钛矿型催化剂组合物
US11439983B2 (en) 2019-03-29 2022-09-13 Johnson Matthey Public Limited Company Active perovskite-type catalysts stable to high temperature aging for gasoline exhaust gas applications
WO2020202144A1 (fr) * 2019-04-01 2020-10-08 Technology Innovation Momentum Fund (Israel) Limited Partnership Synthèse par co-déflagration de particules métalliques, céramiques et mixtes métalliques-céramiques
CN112844354A (zh) * 2020-12-23 2021-05-28 甄崇礼 钙钛矿化合物的制备方法

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