Three-way catalysts having reduced palladium loadings and methods for making same - Patents.com

Abstract

A three-way catalyst for reduced palladium loading is provided. The catalyst includes an inert substrate and a palladium catalytic material coating the substrate. The palladium catalytic material includes a support material formed from one of 10% CeO2 / Al2O3, 20% CeO2-Al2O3 (20CeAlOy), 30% CeO2-Al2O3 (30CeAlOy), Al2O3, and MOx-Al2O3, where M is one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium. The palladium catalytic material includes a layer of CeO2 material disposed on the support material, the layer of CeO2 material being dispersed on a surface of the support material. The palladium catalytic material includes active components including a layer of praseodymium oxide particles dispersed across a surface of a layer of CeO2 material, and a layer of palladium particles disposed on and dispersed across the surface of the layer of CeO2 material, each at locations corresponding to a respective location of each of the praseodymium particles.

Description

[Technical field]

[0001] Government Contracts This application was made with Government support under Contract No. DE-EE0009196 awarded by the Department of Energy. The Government has certain rights in this invention. [Background technology]

[0002] TECHNICAL FIELD This disclosure relates generally to three-way catalysts having reduced palladium loadings and methods of making three-way catalysts.

[0003] Exhaust aftertreatment systems are utilized, for example, to treat an exhaust gas stream generated by the operation of an internal combustion engine. The exhaust gas stream may be defined as a stream of untreated exhaust gas that includes by-products of combustion of a hydrocarbon-containing fuel and oxygen, the stream emanating from an internal combustion engine. These by-products include hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxide (NO). x ). The exhaust aftertreatment system may include a catalytic converter device that includes a three-way catalyst. A three-way catalyst is a device or structure within the catalytic converter device that provides one or more surfaces that are treated with a coating that includes at least one catalyst. A catalyst is a material that promotes the rapid reaction of components of the raw exhaust gas stream to components of the treated exhaust gas stream. Specifically, a catalyst is a material that increases the rate of a chemical reaction without undergoing any permanent change itself. In one example, a three-way catalyst is a material that promotes the rapid reaction of components of the raw exhaust gas stream to components of the treated exhaust gas stream. x The three-way catalyst can promote the rapid conversion of NO, HC, and CO into nitrogen gas (N2), water, and carbon dioxide (CO2) in the treated exhaust gas stream. x and the resulting treated exhaust gas stream comprises water, N2, and CO2. Summary of the Invention

[0004] A three-way catalyst for reduced palladium loading is provided. The three-way catalyst includes an inert substrate and a palladium catalytic material coating the inert substrate. The palladium catalytic material includes a support material formed from a material selected from the group consisting of 10% CeO2 / Al2O3, 20% CeO2-Al2O3 (20CeAlOy), 30% CeO2-Al2O3 (30CeAlOy), Al2O3, MOx-Al2O3, where M is a metal including at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium. The palladium catalytic material further includes a layer of CeO2 material disposed on the support material and having a surface, the layer of CeO2 material being dispersed on the surface of the support material. The palladium catalytic material further includes an active component. The active component includes a first layer of praseodymium oxide particles disposed on and dispersed throughout a surface of the layer of CeO2 material, and a second layer of a plurality of palladium particles disposed on and dispersed throughout the surface of the layer of CeO2 material at a plurality of locations each corresponding to a respective location of each of the plurality of praseodymium particles.

[0005] In some embodiments, the layer of CeO2 material is a base layer of CeO2. The surface of the layer of CeO2 material is a first surface. The base layer of CeO2 includes a plurality of CeO2 nanostructures projecting upward from the first surface, each having a second surface. A first layer of praseodymium particles is disposed on and distributed across the second surface of each of the plurality of CeO2 nanostructures. A second layer of palladium particles is disposed on and distributed across the second surface of each of the plurality of CeO2 nanostructures.

[0006] In some embodiments, the support material is 10% CeO2 / Al2O3 (10CA) formed by impregnation of Ce nitrate onto Al2O3 followed by calcination at a temperature between 500°C and 1050°C for 1 to 5 hours.

[0007] In some embodiments, the support material is 10% CeO2 / Al2O3 (10CA) made by impregnation of Ce nitrate onto Al2O3 followed by calcination at a temperature of 950°C for 2 hours.

[0008] In some embodiments, the support material is Al(OH). x The 10% CeO2 / Al2O3 (10CeAlO y ).

[0009] In some embodiments, the support material is 30CeAlO y It is.

[0010] In some embodiments, the support material is calcined at a temperature between 500° C. and 1050° C. for 2 hours.

[0011] In some embodiments, the support material is 30CeAlO calcined at a temperature of 950° C. for 2 hours. y It is.

[0012] In some embodiments, the support material is MO x -Al2O3.

[0013] In some embodiments, the support material is calcined at a temperature of 550° C. for 2 hours.

[0014] In some embodiments, the active ingredient is zPd-δCe n Pr 1-n O x In the formula, z is 0.1 to 1.5, δ is 5.0 to 40, and n is 0.70 to 0.95.

[0015] In some embodiments, the active ingredient is 0.8Pd-20Ce 0.90 Pr 0.10 O x and 0.8Pd-30Ce 0.90 Pr 0.10 O x is selected from the group consisting of:

[0016] In some embodiments, the second layer of the plurality of palladium particles is formed from a single atom of palladium.

[0017] According to an alternative embodiment, a device is provided. The device includes an internal combustion engine configured to generate an untreated exhaust gas stream, and a catalytic converter including a three-way catalyst. The three-way catalyst promotes a chemical reaction that converts the untreated exhaust gas stream into a treated exhaust gas stream. The three-way catalyst includes an inert substrate and a palladium catalytic material coating the inert substrate. The palladium catalytic material may be selected from the group consisting of 10% CeO2 / Al2O3, 20% CeO2-Al2O3 (20CeAlOy), 30% CeO2-Al2O3 (30CeAlOy), Al2O3, and MO. x -Al2O3, where M is a metal and includes at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium. The palladium catalyst material further includes a layer of CeO2 material disposed on the support material and having a surface, the layer of CeO2 material being dispersed on the surface of the support material, and an active component. The active component includes a first layer of praseodymium oxide particles disposed on and dispersed throughout the surface of the layer of CeO2 material, and a second layer of a plurality of palladium particles disposed on and dispersed throughout the surface of the layer of CeO2 material at a plurality of locations each corresponding to a respective location of each of the plurality of praseodymium particles.

[0018] In some embodiments, the active ingredient is zPd-δCe n Pr 1-n O x In the formula, z is 0.1 to 1.5, δ is 5.0 to 40, and n is 0.70 to 0.95.

[0019] In some embodiments, the active ingredient is 0.8Pd-20Ce 0.90 Pr 0.10 O x It is.

[0020] In some embodiments, the active ingredient is 0.8Pd-30Ce 0.90 Pr 0.10 O x It is.

[0021] In some embodiments, the second layer of the plurality of palladium particles is formed from a single atom of palladium.

[0022] A method of making a three-way catalyst is provided. The method includes making a palladium catalyst material. Making the palladium catalyst includes making 10% CeO2 / Al2O3, 20% CeO2-Al2O3 (20CeAlOy), 30% CeO2-Al2O3 (30CeAlO y ), Al2O3, and MO x-Al2O3, M being a metal and including at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium. Making the palladium catalyst further includes providing a layer of CeO2 on the surface of the support material to form a workpiece, and calcining the workpiece. Making the palladium catalyst further includes providing a layer of CeO2 on the surface of the support and the layer of Ce-containing material to form a precursor, the layer of CeO2 having a first surface, and calcining the precursor to form a calcined precursor. Making the palladium catalyst further includes disposing a liquid co-impregnation composition on the calcined precursor to form a product, the liquid co-impregnation composition including CeO2, praseodymium, and palladium, and calcining the product to form a plurality of CeO2 structures protruding upward from the first surface and an active component on the product. Each of the plurality of CeO2 structures has a second surface. The active component includes a first layer of praseodymium particles disposed on and distributed across the second surface of each of the plurality of CeO2 nanostructures, and a second layer of palladium particles disposed on and distributed across the second surface of each of the plurality of CeO2 nanostructures at a plurality of locations each corresponding to a respective location of each of the plurality of praseodymium particles. The method further includes forming a slurry having a palladium catalytic material, coating an inert substrate of a three-way catalyst with the slurry, and drying the slurry on the inert substrate.

[0023] In some embodiments, the active ingredient is zPd-δCe n Pr 1-n O x In the formula, z is 0.1 to 1.5, δ is 5.0 to 40, and n is 0.70 to 0.95.

[0024] The above and other features and advantages of the present disclosure will become readily apparent from the following detailed description of the best modes for carrying out the disclosure in connection with the accompanying drawings. [Brief description of the drawings]

[0025] [Figure 1] 1 illustrates a schematic diagram of an exemplary catalytic converter device including a three-way catalyst configured to provide exhaust after-treatment to an untreated exhaust gas stream in accordance with the present disclosure. [Diagram 2] 2 illustrates a schematic cross-sectional perspective view of an embodiment of the catalytic converter device of FIG. 1 according to the present disclosure; [Diagram 3] 1 illustrates a schematic diagram of a device including a catalytic converter configured to provide exhaust after-treatment to an exhaust gas stream generated by an internal combustion engine, in accordance with the present disclosure. [Figure 4] Figures 4-6 show an exemplary sequence of manufacturing operations for forming the three-way catalyst of Figure 1 according to the present disclosure. Figure 4 shows generally the first operation, which can be described as an incipient-wetness impregnation (IWI) operation. [Diagram 5] Figures 4-6 show an exemplary sequence of manufacturing operations for forming the three-way catalyst of Figure 1 according to the present disclosure. Figure 5 shows a schematic of a second operation, which may be described as a second incipient wetness impregnation operation. [Figure 6] Figures 4-6 show an exemplary sequence of manufacturing operations for forming the three-way catalyst of Figure 1 according to the present disclosure. Figure 6 shows generally the third operation in which calcination is performed, resulting in evaporation of the residue of the liquid co-impregnation composition of Figure 5. [Figure 7] 2 illustrates a schematic diagram of an alternative embodiment of the three-way catalyst of FIG. 1 including a layer of CeO2 material uniformly distributed on the surface of a support material in accordance with the present disclosure; [Figure 8] 1 is a graph showing infrared spectroscopy analysis of various three-way catalysts with different concentrations of palladium deposited thereon in accordance with the present disclosure. [Figure 9]1 is a graph showing the deactivation of palladium particles on a first three-way catalyst comprising a baseline palladium dispersion and on a second three-way catalyst comprising a palladium dispersion according to the disclosed method, in accordance with the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] An exhaust gas aftertreatment system receives an untreated exhaust gas stream from a device or system, such as an internal combustion engine. The temperature of the untreated exhaust gas stream may vary based on factors such as the output torque provided by the device or system and the ambient temperature. The catalyst in a catalytic converter device may be sensitive to high temperatures. High temperatures may cause the catalyst to wear out, become deactivated, or sinter, reducing its effectiveness.

[0027] A three-way catalyst may include a catalytic monolith structure or a honeycomb-like catalytic cake structure within the three-way catalyst. The catalytic monolith structure includes a plurality of holes that define flow paths through the catalytic monolith structure. Within the flow paths, large surfaces of the catalytic monolith structure are coated or covered with catalytic particles or catalytic material. This coating may be applied as a washcoat, which in the case of a monolith or support structure, can be described as a liquid or slurry material containing solid particles that is used to deposit the solid particles on the surface. The raw exhaust gas stream is directed through these flow paths. Within the flow paths, carbon monoxide, hydrocarbons, and NO are removed. x Chemical constituents of the raw exhaust gas stream, such as palladium, arsenic, and nitric acid, come into contact with the catalytic material and are converted through chemical reactions into compounds such as carbon dioxide, water, and nitrogen gas. After these chemical reactions have occurred, the raw exhaust gas stream becomes a treated exhaust gas stream. Palladium (Pd) is one catalyst that can be utilized as the catalytic material in a three-way catalyst.

[0028] Pd is rare and expensive. It would be beneficial to reduce the amount of Pd used in a three-way catalyst and to reduce the frequency with which the three-way catalyst must be replaced (collectively described as reduced Pd loading). A three-way catalyst having reduced Pd loading and a method for making the same are provided. The three-way catalyst may include an inert substrate, for example, making a honeycomb cake material, and the inert substrate may be coated with a Pd catalytic material.

[0029] The Pd catalyst material may be first formed as a powder, which is then used to make a slurry or washcoat for coating the inert substrate of the three-way catalyst. The powder is highly defective, with CeO2, Pr6O 11 The stabilizing support material may be made in powder form, which may include Al2O3 oxide composites, and Al2O3 oxide composites. The defects on the surface of the powder are useful for attracting the Pd particles and creating sites on the surface that act as binders for the Pd particles. The support material may be described as an inert material onto which the active component may be deposited. The stabilizing support material may be selected or enhanced for the excellent hydrophilic properties of the surface of the support material. On the support material, the Pd particles or single Pd atoms may be widely dispersed as the main active component or may be widely and evenly distributed. In one embodiment, the nano-sized Pd-CePrO xThe active component (having Pd present as dispersed single atoms or having small dispersed clusters of Pd in ​​the fresh catalyst state) can be utilized on an Al2O3 support with superior or enhanced hydrophilic properties. As a result, the Pd catalyst material includes a stabilized support material with Pd particles dispersed widely or up to 100% on the surface of the stabilized support material. In an exemplary embodiment, the stabilized support structure includes an Al2O3 support with a layer of Ce-based material coating the Al2O3 support such that the Pd particles dispersed on the surface are separated from the Al2O3 support by a layer of Ce material. The Pd catalyst material can be provided on the surface of the catalyst monolith structure, for example, by a powder used to make a slurry that is washcoated on the surface of the catalyst monolith structure. The resulting three-way catalyst configuration coated with the disclosed Pd catalyst material exhibits superior aging resistance and comparable performance or activity to a baseline Pd / Al2O3 equipped three-way catalyst while using only 40% of the Pd used by the baseline three-way catalyst. The deactivation of Pd on three-way catalysts can be mitigated or balanced by widely dispersed Pd nanoclusters or single-atom Pd on Pr-modified CeO2 / Al2O3 mixed oxides.

[0030] The Pd catalyst material exhibits a layered structure with the support material covered by small CeO2 particles. These CeO2 particles exhibit a high defect density due to praseodymium (Pr) doping. This stabilized support material containing a high defect density allows for a wide dispersion of Pd single atoms during the wet impregnation process and can avoid sintering under various operating conditions.

[0031] The Pd catalyst material may include a layered support structure that includes Ce-containing particles or CeO2 particles on an exterior surface. During formation on the surface, the Ce-containing particles form crystals. The surface of the crystals formed of the Ce material may be smooth and defect-free. The Pd particles are attracted to the defects on the surface and form bonds with the defects, and if the surface has too few defects, not enough Pd particles may adhere to the surface for the catalyst to be effective. By increasing the number or occurrence of defects on the surface of the Ce material, the Pd particles may be attracted to and widely distributed on the surface of the layered support structure.

[0032] The Pd catalyst material can contain a high or selected defect density by calibrated Pr doping or by forming a surface containing widely dispersed Pr particles. This defect density can be further increased by three-dimensional CeO2 nanostructures that protrude upward from the surface of the material, increasing the overall surface area of ​​the surface, and / or by reducing the Ce crystallite size to increase the density of boundaries between adjacent Ce crystallites. The resulting selected defect density can be used to control and create superior Pd single atom dispersion on the three-way catalyst. This superior Pd dispersion results in superior aging resistance in the Pd on three-way catalyst.

[0033] The method of making a Pd catalytic material for use on a three-way catalyst can be described as utilizing co-impregnation of Pd, Pr, and Ce materials on a support structure. The method can further include utilizing a selected palladium / cerium (Pd / Ce) ratio and a selected praseodymium / cerium (Pr / Ce) ratio.

[0034] A variety of support materials can be utilized to form the Pd catalyst material to provide superior hydrophilic properties. A first embodiment of the support material can include 10CA, which can be described as 10% CeO2 / Al2O3 (10% CeO2 / Al2O3 from Ce nitrate impregnation onto Al2O3, calcined at 950°C for 2 hours). A second embodiment of the support material can include 10CeAlO yThis may include 10% CeO2 / Al2O3 (calcined at 550°C for 2 hours, Al(OH) x A third embodiment of the support material can be described as 30CeAlO y A fourth embodiment of the support material may include 30CeAlO y A fifth embodiment of the support material may include Al2O3-HD, which may be described as Al2O3 with high density. A sixth embodiment of the support material may include MO-950, which may be described as 30% CeO2-Al2O3 calcined at 950° C. for 2 hours. x -Al2O3, which can be described as a commercially available mixed oxide material or M salt impregnation onto Al2O3 followed by calcination at 550°C for 2 hours. M can be a metal and can include copper, iron, manganese, titanium, zirconium, magnesium, strontium, barium, etc. The Al2O3 support material 110 can include any of these support materials.

[0035] A three-way catalyst for reduced palladium loading is provided. The three-way catalyst includes an inert substrate and a palladium catalytic material coating the inert substrate. The palladium catalytic material includes a support material formed from a material selected from the group consisting of 10% CeO2 / Al2O3, 20% CeO2-Al2O3 (20CeAlOy), 30% CeO2-Al2O3 (30CeAlOy), Al2O3, and MOx-Al2O3, where M is a metal including at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, barium, and the like. The palladium catalytic material further includes a layer of CeO2 material disposed on the support material or formed and located on the support material and having a surface, the layer of CeO2 material being dispersed on the surface of the support material. The palladium catalytic material further includes an active component including a first layer of praseodymium oxide particles disposed on and dispersed throughout a surface of the layer of CeO2 material, and a second layer of a plurality of palladium particles disposed on and dispersed throughout the surface of the layer of CeO2 material at a plurality of locations each corresponding to a respective location of each of the plurality of praseodymium particles.

[0036] The layer of CeO2 material can be a base layer of CeO2. The surface of the layer of CeO2 material can be a first surface. The base layer of CeO2 can include a plurality of CeO2 nanostructures projecting upward from the first surface and each having a second surface. A first layer of praseodymium particles can be disposed on and distributed across the second surface of each of the plurality of CeO2 nanostructures. A second layer of palladium particles can be disposed on and distributed across the second surface of each of the plurality of CeO2 nanostructures.

[0037] The support material can be 10% CeO2 / Al2O3 (10CA), formed by impregnation of Ce nitrate onto Al2O3, followed by calcination at a temperature of 500°C to 1050°C for 1 to 5 hours.

[0038] The support material can be 10% CeO2 / Al2O3 (10CA) made by impregnation of Ce nitrate onto Al2O3 and subsequent calcination at a temperature of 950°C for 2 hours.

[0039] The support material is Al(OH) x The 10% CeO2 / Al2O3 (10CeAlO y ).

[0040] The support material is 30CeAlO y It could be.

[0041] The support material may be calcined at a temperature between 500° C. and 1050° C. for 2 hours.

[0042] The support material was 30CeAlO sintered at 950 °C for 2 h. y It could be.

[0043] The support material is MO x -Al2O3.

[0044] The support material may be calcined at a temperature of 550° C. for 2 hours.

[0045] The active ingredient is zPd-δCe n Pr 1-n O x where z is 0.1 to 1.5, δ is 5 to 40, and n is 0.70 to 0.95. Specifically, z can be expressed in parts by weight of the amount of Pd supported based on 100 parts by weight of the active ingredient, δ can be expressed in parts by weight based on 100 parts by weight of the active ingredient, and n can be expressed as a molar ratio.

[0046] The active ingredient is 0.8Pd-20Ce 0.90 Pr 0.10 O x and 0.8Pd-30Ce 0.90 Pr 0.10 O x may be selected from the group consisting of:

[0047] The second layer of the plurality of palladium particles may be formed from a single atom of palladium.

[0048] A device is provided. The device may include a vehicle. The device includes an internal combustion engine configured to generate an untreated exhaust gas stream, and a catalytic converter including a three-way catalyst. The three-way catalyst promotes a chemical reaction that converts the untreated exhaust gas stream into a treated exhaust gas stream. The three-way catalyst includes an inert substrate and a palladium catalytic material coating the inert substrate. The palladium catalytic material may be selected from the group consisting of 10% CeO2 / Al2O3, 20% CeO2-Al2O3 (20CeAlOy), 30% CeO2-Al2O3 (30CeAlOy), Al2O3, and MO. x -Al2O3, where M is a metal and includes at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium. The palladium catalytic material further includes a layer of CeO2 material disposed on the support material and having a surface, the layer of CeO2 material being dispersed on the surface of the support material. The palladium catalytic material further includes an active component. The active component includes a first layer of praseodymium oxide particles disposed on and dispersed throughout the surface of the layer of CeO2 material, and a second layer of a plurality of palladium particles disposed on and dispersed throughout the surface of the layer of CeO2 material at a plurality of locations each corresponding to a respective location of each of the plurality of praseodymium particles.

[0049] The active ingredient is zPd-δCe n Pr 1-n O x wherein z is 0.1 to 1.5, δ is 5 to 40, and n is 0.70 to 0.95.

[0050] The active ingredient is 0.8Pd-20Ce 0.90 Pr 0.10 O x It could be.

[0051] The active ingredient is 0.8Pd-30Ce 0.90Pr 0.10 O x It could be.

[0052] The second layer of the plurality of palladium particles may be formed from a single atom of palladium.

[0053] Referring now to the drawings, in which like reference numbers refer to like features throughout the several views, FIG. 1 illustrates generally an exemplary catalytic converter device 10 including a three-way catalyst 20 that provides exhaust after-treatment to an untreated exhaust gas stream 32. The three-way catalyst 20 includes a disclosed Pd catalytic material including a Pd single atom dispersion. The catalytic converter device 10 includes an inlet 30 and an outlet 40. Each of the inlets 30 and the outlet 40 is connected to an exhaust after-treatment system component, such as a pipe configured to move exhaust gas from one device to a second device. The untreated exhaust gas stream 32 is shown entering the inlet 30. The treated exhaust gas stream 42 is shown exiting the outlet 40.

[0054] FIG. 2 shows a schematic cross-sectional perspective view of one embodiment of the catalytic converter device 10 of FIG. 1. The catalytic converter device 10 includes a three-way catalyst 20 embodied as two catalytic monolith structures 22. Each of the catalytic monolith structures 22 may include a plurality of holes defining flow paths through the catalytic monolith structures 22. The surfaces of the catalytic monolith structures 22, including the surfaces of the flow paths within the catalytic monolith structures 22, may be coated with the disclosed Pd catalytic material. Each of the catalytic monolith structures 22 may include an annular gasket 24 surrounding the catalytic monolith structures 22. The catalytic converter device 10 is further shown to include a first layer 14 of a metal heat shield housing and a second layer 12 of a metal heat shield housing. The catalytic converter device 10 is further shown to include an inlet 30 and an outlet 40.

[0055] FIG. 3 shows a schematic diagram of a device 800 including an internal combustion engine 820 and a catalytic converter device 10. The device 800 is embodied as a vehicle. The engine 820 is connected to a three-way catalyst 20 (FIG. 2) by a pipe or conduit configured for transporting hot exhaust gas. An untreated exhaust gas stream 32 is shown entering the catalytic converter device 10. A treated exhaust gas stream 42 is shown exiting the catalytic converter device 10 as a result of the operation of the three-way catalyst 20 disclosed herein within the catalytic converter device 10. The pipe or conduit exiting the catalytic converter device 10 may be connected to other exhaust aftertreatment devices or structures, such as a muffler device and a tailpipe.

[0056] 4 and 5 show an exemplary sequence of manufacturing operation steps for making a Pd catalyst material used to coat the three-way catalyst 20 of FIG. 1. FIG. 4 shows a schematic of an operation 100 that can be described as an incipient wetness impregnation (IWI) operation, in which an Al2O3 support material 110 is provided. The Al2O3 support material 110 can be in powder form, and the flat appearance of the Al2O3 support material 110 in FIGS. 4-7 can be simplified for illustrative purposes and / or as a result of the substantial enlargement of the Al2O3 support material 110. The Al2O3 support material 110 includes a surface 112. A dispensing nozzle 120 is provided that includes a supply 130 of a Ce-containing solution. In one exemplary embodiment, the Ce-containing solution can include a 10 wt. % Ce(NO3)3 solution. Droplets 132 of the Ce-containing solution are shown being deposited on the surface 112 of the Al2O3 support material 110. A plurality of droplets 132 are deposited on the surface 112 until a selected amount of the Ce-containing solution is disposed on the surface 112. Once the selected amount of the Ce-containing solution is deposited on the surface 112, a heating calcination process is applied to the Al2O3 support material 110. In one embodiment, the calcination process is performed at 950°C. In another embodiment, the calcination process is performed within a temperature range of 500°C to 1050°C. Calcination processes within the relatively high portion of the defined range, such as 950°C or at least above the 795°C melting point of Ce, may be particularly useful, since the Ce in the provided solution may melt to a liquid state and spread and coat most or all of the Al2O3 support material 110 before the Ce subsequently cools and solidifies. As a result of the operation 100, the solvent of the Ce-containing solution evaporates and a layer of Ce-containing compound dries on the surface 112.

[0057] FIG. 5 shows a schematic of an operation 200 that can be described as a co-impregnation process. As a result of the operation 100 of FIG. 2, the Al2O3 support material 110 is shown including a layer of Ce-containing compound 240 dried on the surface 112. The Ce-containing compound 240 may cover a majority of the surface 112 or may cover the entire surface 112. In the operation 200, a liquid co-impregnation composition 205 is applied to the Al2O3 support material 110 and the Ce-containing compound 240. In one embodiment, the liquid co-impregnation composition 205 may include Pd(NO3)2, Pr(NO3)3, and a Ce-containing liquid. The Ce-containing liquid may include colloidal CeO2 or cerium nitrate (Ce(NO3)3). The operation 200 may include a calcination at a relatively low temperature compared to the operation 100, including, for example, a calcination at 500° C., resulting in evaporation of the liquid components of the liquid co-impregnation composition 205 of FIG. 5.

[0058] As a result of the co-impregnation process of operation 200 and subsequent calcination, additional newly deposited Ce-containing material is disposed on the Ce-containing compound 240 in the form of a plurality of Ce crystals. When the liquid co-impregnation composition 205 includes cerium nitrate, the resulting surface of the deposited Ce-containing material may be relatively flat or may conform to the shape of the Al2O3 support material 110 beneath the deposited Ce material. When the liquid co-impregnation composition 205 includes colloidal CeO2, the resulting surface of the deposited Ce-containing material may include three-dimensional features that can be described as CeO2 nanostructures protruding upward from the surface. Additionally, Pr particles are dispersed throughout the newly deposited Ce-containing material. The boundaries between the Ce crystals of the newly deposited Ce-containing material can attract and create chemical bonds with the Pd particles. Additionally, the Pr particles dispersed in the newly deposited Ce-containing material can create defects on the surface of the Ce-containing material, which can attract and create chemical bonds with the Pd particles. By controlling the Ce crystal size and by controlling how much Pr is dispersed in the deposited Ce-containing material, one can control how widely or efficiently the Pd particles are dispersed across the surface of the deposited Ce-containing material. In one embodiment, with sufficient defects created in the surface of the deposited Ce-containing material, single atomic Pd particles can be dispersed across the surface of the resulting Pd catalyst material.

[0059] FIG. 6 is a schematic illustration of an embodiment of a Pd catalyst material 500 formed as a result of the operation 200 of FIG. 5, where the surface of the Pd catalyst material 500 includes CeO2 nanostructures 450. An Al2O3 support material 110 is shown with a Ce material 440 coating the surface 112. CeO2 nanostructures 450 are shown formed on the Ce material 440 consistent with the operation 200 of FIG. 5 utilizing a liquid co-impregnation composition 205 including colloidal CeO2. Each of the CeO2 nanostructures 450 includes a plurality of Pr particles dispersed in the CeO2 material. Each of the CeO2 nanostructures 450 is shown with a plurality of Pd particles 560 shown disposed on the CeO2 nanostructures 450 at positions corresponding to the Pr particles on the CeO2 nanostructures 450. FIG. 6 is provided for illustrative purposes and may not be drawn to scale since the Pd particles 560 may be single Pd atoms.

[0060] FIG. 7 is a schematic diagram of an alternative embodiment of a Pd catalyst material 900 including a layer 940 of CeO2 material uniformly distributed on the surface 112 of the support material 110. The support material 110 is shown including the layer 940 formed on the surface 112. The layer 940 may include a relatively flat surface 942, consistent with the operation 200 of FIG. 5 utilizing a liquid co-impregnation composition 205 including cerium nitrate. The surface 942 includes Pr particles deposited and disposed on the surface 942. A plurality of Pd particles 560 are shown disposed on the surface 942 at locations corresponding to the Pr particles disposed on the surface 942. FIG. 7 is provided for illustrative purposes and may not be drawn to scale since the Pd particles 560 may be single Pd atoms.

[0061] The active ingredient coating containing Pd can be dispersed on the Al2O3 support material 110 of FIG. 4 after a drying or calcination process is utilized such that the coating is a dry layer on the Al2O3 support material 110. Numerous combinations of Pd and support materials are envisioned, resulting in numerous formulations for the Pd catalyst material. In a first embodiment of the Pd catalyst material, 0.8Pd-20Ce n Pr 1-n O x / 10CA is a 0.8 wt% Pd and 20% Ce on a 10CA support calcined at 550 °C for 2 h. n Pr 1-n O x (n=1, 0.95, 0.9, 0.8, or 0.7). In a second embodiment of the Pd catalyst material, 0.8Pd-20Ce 0.9 Pr 0.1 O x is a 0.8 wt% Pd and 20% Ce alloy calcined at 550°C for 2 hours. 0.9 Pr 0.1 O x The following supports can be described as co-IWIs: 10CeAlO y , 30CeAlO y , 30CeAlO y -950, Al2O3-HD, and MO x In a third embodiment of the Pd catalyst material, 0.8Pd-30Ce 0.9 Pr 0.1 O x is a 0.8 wt% Pd and 30% Ce alloy calcined at 550°C for 2 hours. 0.9 Pr 0.1 O x The IWI can be described as a combination of the following supports: Al2O3-HD and MO x -Al2O3.

[0062] 8 is a graph 700 showing infrared spectroscopy of various three-way catalysts with different concentrations of Pd deposited thereon according to the disclosed method. The horizontal axis 702 is wavenumber (cm -1 The vertical axis 704 shows normalized absorbance (measured in arbitrary units (Au)). Plot 710 shows 0.2Pd (oxidized at 500° C.). Plot 720 shows 0.4Pd (oxidized at 500° C.). Plot 730 shows 0.6Pd (oxidized at 500° C.). Plot 740 shows 1.2Pd (oxidized at 500° C.). -1The wavenumber at 2108 cm corresponds to the CO stretch on the Pd cation (signature of a single-atom Pd species). -1 The wavenumbers correspond to the C-O stretching on the Pd clusters (signature of sub-nanometer Pd clusters). In accordance with the disclosed method, graph 700 shows that the use of colloidal CeO2 precursor and Pr co-impregnation leads to the formation of significantly smaller CeO2 particles and higher defect density, thus minimizing the formation of large Pd particles.

[0063] FIG. 9 is a graph 600 showing the deactivation of palladium particles on a first three-way catalyst containing a baseline palladium dispersion and on a second three-way catalyst containing a palladium dispersion according to the disclosed method. Graph 600 includes a horizontal axis 602 representing the time the three-way catalyst has been in use. Graph 600 further includes a vertical axis 604 representing the percent dispersion of activated Pd particles on the three-way catalyst. Plot 610 represents the percent of activated Pd particles on a three-way catalyst containing a baseline palladium dispersion over time, the three-way catalyst being made without the benefit of the disclosed method. Plot 610 represents a three-way catalyst that starts with about 50% dispersion of activated Pd particles and includes agglomerates or agglomerates of Pd having an average diameter or thickness of 3-5 nanometers. With the use of such Pd agglomerates, not all of the Pd atoms are exposed to be useful as a catalyst, but these particles are still deactivated over time. Furthermore, the Pd particles do not have a layer of Ce separating them from the support material, such as Al2O3. As a result, the Pd particles represented by plot 610 are deactivated at a relatively rapid rate. Plot 620 represents the percentage of active Pd particles over time on a three-way catalyst made according to the disclosed method. Plot 620 begins at the left position and represents the initial state of the three-way catalyst at 100% or near 100% dispersion, representing that Pd is dispersed as single atomic Pd particles on the surface of the three-way catalyst. The wide dispersion of single atomic Pd particles and the layer of Ce-containing material separating the Pd particles from the support material allow the three-way catalyst represented by plot 620 to resist Pd particle deactivation over time better than the three-way catalyst represented by plot 610, resulting in a relatively slower deactivation rate of Pd particles on the three-way catalyst represented by plot 620. As a result, the three-way catalyst represented by plot 620 having the structure described herein and / or made according to the methods disclosed herein starts at a higher dispersion percentage and suffers from deactivation over time at a relatively slower rate than the three-way catalyst represented by plot 610.As a result, three-way catalysts having the structures described herein and / or made according to the methods disclosed herein may contain reduced Pd loadings compared to three-way catalysts that include a baseline palladium dispersion.

[0064] A method of making a three-way catalyst is provided. The method includes making a palladium catalytic material. Making the palladium catalytic material includes making 10% CeO2 / Al2O3, 20% CeO2-Al2O3 (20CeAlOy), 30% CeO2-Al2O3 (30CeAlO y ), Al2O3, and MO x-Al2O3, where M is a metal and includes at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium. Making the palladium catalytic material further includes providing a layer of CeO2 on the surface of the support material to form a workpiece, and calcining the workpiece. Making the palladium catalytic material further includes providing a layer of CeO2 on the surface of the support and the layer of Ce-containing material to form a precursor, the layer of CeO2 having a first surface, and calcining the precursor to form a calcined precursor. Making the palladium catalytic material further includes disposing a liquid co-impregnation composition on the calcined precursor to form a product, the liquid co-impregnation composition including CeO2, praseodymium, and palladium, and calcining the product to form a plurality of CeO2 structures protruding upward from the first surface and an active component on the product. Each of the plurality of CeO2 structures has a second surface. The active component includes a first layer of praseodymium particles disposed on and distributed across the second surface of each of the plurality of CeO2 nanostructures, and a second layer of palladium particles disposed on and distributed across the second surface of each of the plurality of CeO2 nanostructures at a plurality of locations each corresponding to a respective location of each of the plurality of praseodymium particles. The method further includes forming a slurry having a palladium catalytic material, coating an inert substrate of a three-way catalyst with the slurry, and drying the slurry on the inert substrate.

[0065] The active ingredient is zPd-δCe n Pr 1-n O x wherein z is 0.1 to 1.5, δ is 5 to 40, and n is 0.70 to 0.95.

[0066] The active ingredient is 0.8Pd-20Ce 0.90 Pr 0.10 O x It could be.

[0067] The active ingredient is 0.8Pd-30Ce 0.90 Pr 0.10 O x It could be.

[0068] Although the best mode for carrying out the present disclosure has been described in detail, those skilled in the art to which the present disclosure pertains will recognize various alternative designs and embodiments for practicing the present disclosure within the scope of the appended claims.

Claims

1. A three-way catalyst for reduced palladium loading, comprising: An inactive substrate; a palladium catalytic material coating the inert substrate, the palladium catalytic material comprising: 10% CeO ２ / Al ２ O ３ , 20% CeO ２ -Al ２ O ３ (20CeAlOy), 30%CeO ２ -Al ２ O ３ (30CeAlOy), Al ２ O ３ , and MOx-Al ２ O ３ wherein M is a metal comprising at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium; CeO disposed on the support material and having a surface. ２ A layer of material, the CeO ２ A layer of material is dispersed on the surface of the support material, CeO ２ A layer of material; An active ingredient, The CeO ２ a first layer of praseodymium oxide particles disposed on and dispersed across the surface of the layer of material; At a plurality of positions each corresponding to a respective position of each of the plurality of praseodymium particles, the CeO ２ a second layer of a plurality of palladium particles disposed on and dispersed across the surface of the layer of material; and an active component comprising:

2. The CeO ２ The layer of material is CeO ２ is the base layer of The CeO ２ the surface of the layer of material is a first surface; The CeO ２ a base layer of CeO projecting upwardly from the first surface, each having a second surface. ２ Contains a nanostructure, The first layer of praseodymium particles is ２ disposed on and distributed across the second surface of each of the nanostructures; The second layer of the plurality of palladium particles is ２ 10. The three-way catalyst of claim 1 , wherein the nanostructures are disposed on and distributed across the second surface of each of the nanostructures.

3. The support material is Al ２ O ３ 10% CeO formed by impregnation of Ce nitrate onto the substrate and subsequent calcination at temperatures between 500° C. and 1050° C. for 1 to 5 hours. ２ / Al ２ O ３ The three-way catalyst according to claim 1, wherein the cation exchange ratio is 10 CA.

4. The support material is Al ２ O ３ 10% CeO made by impregnation with Ce nitrate on the substrate and subsequent calcination at a temperature of 950° C. for 2 hours. ２ / Al ２ O ３ The three-way catalyst according to claim 1, wherein the cation exchange ratio is 10 CA.

5. The support material is Al(OH) ｘ 10% CeO made by impregnation with Ce nitrate on the substrate and subsequent calcination at a temperature of 550° C. for 2 hours. ２ / Al ２ O ３ (10CeAlO ｙ 2. The three-way catalyst according to claim 1 ,

6. The support material is 30CeAlO ｙ The three-way catalyst according to claim 1 ,

7. The three-way catalyst of claim 6, wherein the support material is calcined at a temperature between 500° C. and 1050° C. for 2 hours.

8. The support material is 30CeAlO sintered at a temperature of 950° C. for 2 hours. ｙ The three-way catalyst according to claim 1 ,

9. The support material is MO ｘ -Al ２ O ３ The three-way catalyst according to claim 1 ,

10. 10. The three-way catalyst of claim 9, wherein the support material is calcined at a temperature of 550°C for 2 hours.

11. The active ingredient is zPd-δCe ｎ P １－ｎ O ｘ 2. The three-way catalyst of claim 1, wherein z is from 0.1 to 1.5, δ is from 5.0 to 40, and n is from 0.70 to 0.

95.

12. The active ingredient is 0.8Pd-20Ce ０．９０ P ０．１０ O ｘ and 0.8Pd-30Ce ０．９０ P ０．１０ O ｘ The three-way catalyst of claim 1 selected from the group consisting of:

13. 2. The three-way catalyst of claim 1, wherein said second layer of said plurality of palladium particles is formed from a single atom of palladium.

14. A device, comprising: an internal combustion engine configured to generate an untreated exhaust gas stream; a catalytic converter including a three-way catalyst, the three-way catalyst promoting a chemical reaction to convert the untreated exhaust gas stream into a treated exhaust gas stream, the three-way catalyst comprising: An inactive substrate; a palladium catalytic material coating the inert substrate, the palladium catalytic material comprising: 10% CeO ２ / Al ２ O ３ , 20% CeO ２ -Al ２ O ３ (20CeAlOy), 30%CeO ２ -Al ２ O ３ (30CeAlOy), Al ２ O ３ , and M.O. ｘ -Al ２ O ３ wherein M is a metal and includes at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium; CeO disposed on the support material and having a surface. ２ A layer of material, the CeO ２ A layer of material is dispersed on the surface of the support material, CeO ２ A layer of material; An active ingredient, The CeO ２ a first layer of praseodymium oxide particles disposed on and dispersed across the surface of the layer of material; At a plurality of positions each corresponding to a respective position of each of the plurality of praseodymium particles, the CeO ２ a second layer of a plurality of palladium particles disposed on and dispersed across the surface of the layer of material; and an active component comprising:

15. The active ingredient is zPd-δCe ｎ P １－ｎ O ｘ 15. The device of claim 14, wherein z is from 0.1 to 1.5, δ is from 5.0 to 40, and n is from 0.70 to 0.

95.

16. The active ingredient is 0.8Pd-20Ce ０．９０ P ０．１０ O ｘ The device of claim 14 .

17. The active ingredient is 0.8Pd-30Ce ０．９０ P ０．１０ O ｘ The device of claim 14 .

18. The device of claim 14 , wherein the second layer of the plurality of palladium particles is formed from a single atom of palladium.

19. 1. A method of making a three-way catalyst, the method comprising: Making a palladium catalytic material, 10% CeO ２ / Al ２ O ３ , 20% CeO ２ -Al ２ O ３ (20CeAlOy), 30%CeO ２ -Al ２ O ３ (30CeAlO ｙ ), Al ２ O ３ , and M.O. ｘ -Al ２ O ３ wherein M is a metal and includes at least one of copper, iron, manganese, titanium, zirconium, magnesium, strontium, and barium; providing a layer of a Ce-containing material on a surface of the support material to form a workpiece; Firing the workpiece; and On the surface of the support and on the layer of Ce-containing material, ２ forming a precursor by providing a layer of CeO ２ forming a layer of the material having a first surface; calcining the precursor to form a calcined precursor; disposing a liquid co-impregnation composition on the calcined precursor to form a product, the liquid co-impregnation composition comprising CeO ２ forming a palladium-containing oxide, comprising: The product is fired to form a plurality of CeO ２ and forming a structure and an active component on the product, the plurality of CeO ２ Each of the structures has a second surface, and the active ingredient is Multiple CeO ２ a first layer of praseodymium particles disposed on and dispersed across the second surface of each of the nanostructures; At a plurality of locations each corresponding to a respective location of each of the plurality of praseodymium particles, ２ a second layer of a plurality of palladium particles disposed on and dispersed across the second surface of each of the nanostructures; forming a slurry having the palladium catalytic material; coating an inert substrate of the three-way catalyst with the slurry; and drying the slurry on the inert substrate.

20. The active ingredient is zPd-δCe ｎ P １－ｎ O ｘ 20. The method of claim 19, wherein z is from 0.1 to 1.5, δ is from 5.0 to 40, and n is from 0.70 to 0.95.

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