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EP-4739432-A1 - THREE-WAY CATALYSTS COMPRISING MULTIPLE OXYGEN STORAGE COMPONENTS

EP4739432A1EP 4739432 A1EP4739432 A1EP 4739432A1EP-4739432-A1

Abstract

This disclosure relates to a three-way conversion (TWC) catalyst effective to abate NOx, hydrocarbons and carbon monoxide from a gasoline engine exhaust gas, the catalyst including a substrate having a first platinum group metal (PGM) component and, optionally, a second PGM component disposed thereon, wherein a) the first PGM component includes Pt at least partially deposited onto a first oxygen storage component (OSC) which is substantially free of lanthana, and b) the second PGM component is at least partially deposited onto a second OSC which is doped with lanthana.

Inventors

  • ZHENG, XIAOLAI
  • LI, YUEJIN
  • SUNDERMANN, ANDREAS

Assignees

  • BASF Mobile Emissions Catalysts LLC

Dates

Publication Date
20260513
Application Date
20240702

Claims (20)

  1. 1. A three-way conversion (TWC) catalyst effective to abate NOx, hydrocarbons and carbon monoxide from a gasoline engine exhaust gas, the TWC catalyst comprising: a substrate having a washcoat disposed thereon, wherein the washcoat comprises: a) a first PGM component comprising Pt at least partially deposited onto a first oxygen storage component (OSC) which is substantially free of lanthana, and b) a second PGM component is at least partially deposited onto a second OSC which is doped with lanthana.
  2. 2. The TWC catalyst of claim 1, wherein the first PGM component further comprises Rh.
  3. 3. The TWC catalyst of claim 1, wherein the second PGM component comprises at least Pd, Rh, or a combination thereof.
  4. 4. The TWC catalyst of claim 1, wherein the first OSC comprises ceria in an amount of 5 to 75 wt. %, based on the total weight of the first OSC.
  5. 5. The TWC catalyst of claim 1, wherein the first OSC comprises zirconia in an amount of 25 to 95 wt. %, based on the total weight of the first OSC.
  6. 6. The TWC of claim 1, wherein the first OSC is substantially free of rare earth metal oxides other than CeO2.
  7. 7. The TWC catalyst of claim 1, wherein the first OSC comprises a dopant selected from yttria, praseodymia, neodymia, and combinations thereof.
  8. 8. The TWC catalyst of claim 7, wherein the first OSC comprises yttria, praseodymia, neodymia, and combinations thereof in a total amount of up to about 15 wt. %, based on the weight of the first OSC.
  9. 9. The TWC catalyst of claim 1, wherein the second OSC further comprises a dopant selected from yttria, praseodymia, neodymia, and combinations thereof.
  10. 10. The TWC catalyst of claim 9, wherein the second OSC comprises yttria, praseodymia, lanthana, neodymia, and combinations thereof in a total amount of up to about 15 wt. %, based on the weight of the second OSC.
  11. 11. The TWC catalyst of claim 1, wherein the substrate is a honeycomb substrate and wherein the first PGM component and the second PGM component are mixed in a single layer on the substrate.
  12. 12. The TWC catalyst of claim 1, wherein the first PGM component is in a first layer directly disposed on the substrate and the second PGM component is in a second layer which overlies the first layer.
  13. 13. The TWC catalyst of claim 1, wherein the second PGM component is in a second layer directly disposed on the substrate and the first PGM component is in a first layer which overlies the second layer.
  14. 14. The TWC catalyst of claim 1, wherein the substrate has an axial length and an upstream end and a downstream end, and wherein the first PGM component is disposed in a first zone in the downstream end and the second PGM component is disposed in a second zone in the upstream end.
  15. 15. The TWC catalyst of claim [[13]] 14, further comprising a third layer comprising a PGM component at least partially deposited onto a oxygen storage component (OSC) which is substantially free of lanthana, wherein the third layer is disposed at least partially in overlap with the first zone and the second zone.
  16. 16. The TWC catalyst of claim 1, wherein the catalyst does not include the second PGM component.
  17. 17. The TWC catalyst of claim 1, wherein the substrate is a wall-flow filter having alternating inlet passages and outlet passages.
  18. 18. The TWC catalyst of claim 1, wherein the first PGM component comprises Pt in an amount of about 0.01 to about 5 wt. %, based on the total washcoat loading.
  19. 19. The TWC catalyst of claim 1, wherein the second PGM component comprises Pd, Rh, or a combination thereof in a total amount of about 0.01 to about 5 wt. %, based on the weight of the total washcoat loading.
  20. 20. An exhaust gas treatment system comprising a gasoline engine and the three-way conversion (TWC) catalyst of claim 1 downstream from the engine.

Description

THREE-WAY CATALYSTS COMPRISING MULTIPLE OXYGEN STORAGE COMPONENTS TECHNICAL FIELD [0001] This disclosure relates to a three-way conversion (TWC) catalyst composition and a catalytic article useful for the treatment of the automobile internal combustion engine exhaust gases to reduce pollutants contained therein. Particularly, the presently claimed invention relates to a catalyst composition and the catalytic article comprising a platinum group metal. BACKGROUND [0002] Various catalysts and catalyst systems are known for the treatment of internal combustion engine exhaust gases which typically contain pollutants such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). These pollutants are required to be substantially removed from the exhaust gases to meet strict government regulations. Three- way conversion (TWC) catalysts are commonly utilized for treating the exhaust gases emitted from gasoline-powered vehicles. The TWC catalysts and the relevant systems are based on platinum group metals (PGM) such as platinum, palladium, and rhodium. Recently, there has been a renewed interest in the automobile industry to utilize Pt for TWC applications, given its current low price in the market. Commercial Pd-Rh based TWC catalysts typically use a lanthana-doped ceria-zirconia as an oxygen storage component (OSC). Such a lanthana-doped OSC can be activated by Pd and/or Rh but may not be sufficiently activated in the presence of Pt as an active catalytic component. As a result, there is a need to discover an OSC material which can effectively be activated by Pt. SUMMARY [0003] We provide a three-way conversion (TWC) catalyst effective to abate NOx, hydrocarbons and carbon monoxide from a gasoline engine exhaust gas, the catalyst including a substrate having a first platinum group metal (PGM) component and, optionally, a second PGM component disposed thereon, wherein a) the first PGM component comprises Pt at least partially deposited onto a first oxygen storage component (OSC) which is substantially free of lanthana, and b) the second PGM component is at least partially deposited onto a second OSC which is doped with lanthana. [0004] We further provide an exhaust gas treatment system comprising a gasoline engine and the three-way conversion (TWC) catalyst downstream from the engine and a method of treating exhaust gas from a gasoline engine, comprising contacting the exhaust gas with the TWC. BRIEF DESCRIPTION OF THE FIGURES [0005] Figure 1 shows a graph of the light-off temperatures of 2%Pt/OSC samples on the powder TWC light-off test protocol (Lambda = 1) after lean/rich cyclic aging at 1000°C for 5hr. [0006] Figure 2 shows a graph of the light-off Temperatures of 2%Pd/OSC samples on the powder TWC light-off test protocol (Lambda = 1) after lean/rich cyclic aging at 1000°C for 5hr. [0007] Figure 3 shows a graph of the light-off Temperatures of 0.5%Rh/OSC samples on the powder TWC light-off test protocol (Lambda = 1) after lean/rich cyclic aging at 1000°C for 5hr. [0008] Figure 4 shows a graph of the light-off Temperatures of l%Pt-0.25%Rh/OSC samples on the powder TWC light-off test protocol (Lambda = 1) after lean/rich cyclic aging at 1000°C for 5hr. [0009] Figure 5 shows a graph of the oxygen storage capacities of 2%Pt/OSC samples on the powder OSC test protocol after lean/rich cyclic aging at 1000°C for 5hr. [0010] Figure 6 shows a graph of the oxygen storage capacities of l%Pt-0.25%Rh/OSC samples on the powder OSC test protocol after lean/rich cyclic aging at 1000°C for 5hr. [0011] Figure 7 shows a chart of Pt crystallite sizes of 2%Pt on 30% CeO? OSC from Rietveld refinement of Pt(l l l) face at -39.5° 2-theta angle on X-ray diffraction (XRD) after lean/rich aging at 1000°C for 5hr. [0012] Figures 8A-8H show schematics of general designs of TWC catalysts (OSC-L the first oxygen storage component; OSC-2: the second oxygen storage component). [0013] Figure 9A is a perspective view of a honeycomb-type substrate carrier which may comprises the TWC catalyst composition in accordance with one embodiment of the presently claimed invention. [0014] Figure 9B is a partial cross-section view enlarged relative to FIG. 9A and taken along a plane parallel to the end faces of the substrate carrier of FIG. 9A, which shows an enlarged view of a plurality of the gas flow passages shown in FIG. 9A. DETAILED DESCRIPTION [0015] It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, and/or functions of the invention. Exemplary embodiments of components, arrangement, and configurations are described below to simplify the present disclosure, however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This re