Novel Trimetallic Platinum Group Metal (PGM) Catalyst for Gasoline Engine Exhaust Gas Treatment

Abstract

A three-way catalyst article and its use in an exhaust system for an internal combustion engine are disclosed. The catalyst article for treating exhaust gases includes a substrate including an inlet end and an outlet end having an axial length L, a first catalyst region including a first platinum group metal (PGM) component, the first PGM component including Rh and Pt, and a second catalyst region including a second PGM component, the second PGM component including Pd, and the first PGM component having a Pt to Rh ratio of at least 1:20.

Description

Technical Field

[0001] The present invention relates to a catalyst article useful for treating exhaust gas emissions from gasoline engines.

Background Art

[0002] In internal combustion engines, exhaust gas containing various pollutants including hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (nitrogen oxide, “NO x ”) is generated. Emission control systems including exhaust gas catalytic conversion catalysts are widely used to reduce the amount of these pollutants discharged into the atmosphere. The catalyst commonly used for exhaust treatment of gasoline engines is a three-way catalyst (TWC). The TWC performs the following three main functions: (1) oxidation of CO, (2) oxidation of unburned HC, and (3) reduction of NO x .

[0003] Palladium (Pd) and rhodium (Rh) have been widely used in TWC formulations to reduce harmful emissions in gasoline vehicles. However, in recent years, due to the increasing demand in the market, the prices of these precious metals have risen and become even more expensive. On the other hand, due to increasingly stringent environmental regulations worldwide, the automotive industry has been forced to put more precious metals into their catalytic converters.

[0004] On the one hand, platinum (Pt) has become an increasingly attractive candidate for gasoline applications due to its relatively low cost. Over the past 12 months (from September 2020, according to http: / / www.platinum.matthey.com), the average prices of Pt, Pd, and Rh were approximately $888, $2059, and $8468 per ounce, respectively. Therefore, while desiring to maintain equivalent catalytic performance, there is a significant financial incentive regarding how to introduce Pt into the catalyst formulation to at least partially replace Pd and / or Rh.

[0005] In the present invention, through thorough research, the inventors have not only successfully developed and tested a cost-effective new catalyst design, but surprisingly, have been able to achieve equivalent performance, and even significantly improved performance (e.g., improved NO X emission reduction performance).

Summary of the Invention

[0006] One aspect of the present disclosure is a catalyst article for treating exhaust gas, comprising a substrate including an inlet end and an outlet end having an axial length L, a first catalyst region including a first platinum group metal (PGM) constituent, wherein the first PGM constituent includes Rh and Pt, a first catalyst region, and a second catalyst region including a second PGM constituent, wherein the second PGM constituent includes Pd, and the first PGM constituent has a Pt to Rh ratio of at least 1:20 by weight, and a second catalyst region.

[0007] The present invention also encompasses an exhaust system for an internal combustion engine comprising the three-way catalyst constituent of the present invention.

[0008] The present invention also encompasses the treatment of exhaust gas from an internal combustion engine, particularly the treatment of exhaust gas from a gasoline engine. The method includes contacting the exhaust gas with the three-way catalyst constituent of the present invention.

Brief Description of the Drawings

[0009] [Figure 1a] An embodiment of the present invention is shown, in which a first catalyst region extends as the uppermost layer to 100% of the axial length L, and a second catalyst region extends as the bottom layer to 100% of the axial length L. [Figure 1b] The deformed form of Figure 1a is illustrated. [Figure 2a] An embodiment of the present invention is shown, in which a first catalyst region extends from the inlet end to less than 100% of the axial length L, and a second catalyst region extends from the outlet end to less than 100% of the axial length L. The total length of the second catalyst region and the first catalyst region is less than or equal to the axial length L. [Figure 2b] The deformed form of Figure 2a is illustrated. [Figure 2c] An embodiment of the present invention is shown in which a first catalyst region extends from the inlet end to less than 100% of the axial length L, and a second catalyst region extends from the outlet end to less than 100% of the axial length L. The total length of the second and first catalyst regions is greater than the axial length L. [Figure 2d] The deformed form of Figure 2c is illustrated. [Figure 3a] An embodiment of the present invention is shown in which a second catalyst region extends from the inlet end to less than 100% of the axial length L, and a third catalyst region extends from the outlet end to less than 100% of the axial length L. The total lengths of the second and third catalyst regions are less than or equal to the axial length L, but in some embodiments, the total lengths of the second and third catalyst regions may be longer than the axial length, with overlap between the second and third catalyst regions. The first catalyst region extends to 100% of the axial length L and overlaps the second and third catalyst regions as the uppermost layer. [Figure 3b] The deformed form of Figure 3a is illustrated. [Figure 3c] The deformed form of Figure 3a is illustrated. [Figure 3d] The deformed form of Figure 3a is illustrated. [Modes for carrying out the invention]

[0010] The present invention relates to catalytic treatment of combustion exhaust gases, such as those produced by gasoline engines and other engines, and to related catalytic compositions, catalytic articles, and systems. More specifically, the present invention relates to optimized Pt, Pd, Rh ratio and range control compared to conventional Pd / Rh TWC catalysts, and to NO in vehicle exhaust systems. x This relates to a cost-effective method for designing novel TWCs through the simultaneous processing of CO and HC.

[0011] One aspect of the present disclosure relates to a catalyst article for treating exhaust gas, comprising: a substrate including an inlet end and an outlet end having an axial length L; a first catalyst region comprising a first platinum group metal (PGM) component, wherein the first PGM component comprises Rh and Pt; and a second catalyst region comprising a second PGM component, wherein the second PGM component comprises Pd, and the first PGM component has a weight ratio of at least 1:20 Pt to Rh.

[0012] Through thorough research, the inventors have found that in TWC catalysts, partially substituting Pd and / or Rh with Pt under suitable Pt / Pd substitution ratios and optimized Pt / Rh ratios not only significantly reduces PGM costs but also demonstrates that these formulations exhibit superior catalytic properties (see, for example, Examples 1-4 and Tables 2, 3, 5, and 7).

[0013] First catalytic region In some embodiments, the first PGM component may have a Pt-to-Rh ratio of at least 1:15, preferably at least 1:10, and more preferably at least 1:8, 1:6, 1:5, or 1:2. Alternatively, in certain embodiments, the first PGM component may have a Pt-to-Rh ratio of 20:1 to 1:20, 15:1 to 1:15, 10:1 to 1:10, 5:1 to 1:5, or 2:1 to 1:2.

[0014] In some embodiments, the Pt-to-Pd ratio in the first catalyst region to the Pd-to-Citrate ratio in the second catalyst region may be at least 1:200 by weight. In certain embodiments, the Pt-to-Pd ratio in the first catalyst region to the Pd-to-Citrate ratio in the second catalyst region may be at least 1:150, 1:100, or 1:75 by weight. In further embodiments, the Pt-to-Pd ratio in the first catalyst region to the Pd-to-Citrate ratio in the second catalyst region may be at least 1:50, 1:25, 1:20, 1:15, 1:10, 1:8, 1:3, or 1:2. Alternatively, in some embodiments, the ratio of Pt in the first catalytic region to Pd in ​​the second catalytic region may be 200:1 to 1:200, 150:1 to 1:150, 100:1 to 1:100, 75:1 to 1:75, 50:1 to 1:50, 25:1 to 1:25, 20:1 to 1:20, 10:1 to 1:10, 8:1 to 1:8, 3:1 to 1:3, or 2:1 to 1:2.

[0015] The first catalytic region may further include a first oxygen storage capacity (OSC) material, a first inorganic oxide, or a combination thereof.

[0016] The first OSC material may be cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, alumina-ceria-zirconia mixed oxide, or a combination thereof. More preferably, the first OSC material includes ceria-zirconia mixed oxide, alumina-ceria-zirconia mixed oxide, or a combination thereof. The ceria-zirconia mixed oxide may further contain dopants such as lanthanum, neodymium, praseodymium, or yttrium oxide. The first OSC material may function as a carrier material for the first PGM component (for example, as the first PGM carrier material). In some embodiments, the first OSC material includes ceria-zirconia mixed oxide and alumina-ceria-zirconia mixed oxide.

[0017] The first inorganic oxide is preferably an oxide of an element from Group 2, Group 3, Group 4, Group 5, Group 13, and Group 14. The first inorganic oxide is preferably selected from the group consisting of alumina, magnesia, silica, zirconia, barium oxide, and mixed or composite oxides thereof. Particularly preferred is the first inorganic oxide being alumina, lanthanum-alumina, zirconia, or a magnesia / alumina composite oxide. One particularly preferred first inorganic oxide is alumina or lanthanum-alumina.

[0018] The first OSC material and the first inorganic oxide may have a weight ratio of 10:1 or less, preferably 8:1 or 5:1 or less, more preferably 4:1 or 3:1 or less, and most preferably 2:1 or less.

[0019] Alternatively, the first OSC material and the first inorganic oxide may have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8 or 5:1 to 1:5, more preferably 4:1 to 1:4 or 3:1 to 1:3, and most preferably 2:1 to 1:2.

[0020] In some embodiments, the first OSC material and the first inorganic oxide may have a weight ratio of 2:1 or greater. In further embodiments, the first OSC material and the first inorganic oxide may have a weight ratio of 10:1 or greater. In yet another further embodiment, the first OSC material and the first inorganic oxide may have a weight ratio of 20:1 or greater or 30:1 or greater. In yet another further embodiment, the first OSC material and the first inorganic oxide may have a weight ratio of 40:1 or greater or 50:1 or greater.

[0021] The first catalyst region may further contain a first alkali metal or alkaline earth metal.

[0022] The first alkali metal or alkaline earth metal is preferably barium or strontium, and mixed or composite oxides thereof. Preferably, if present, the barium or strontium is packed in an amount of 0.1 to 15% by weight, and more preferably 3 to 10% by weight, based on the total weight of the first catalyst region.

[0023] Preferably, barium or strontium exists as BaCO3 or SrCO3. Such materials can be produced by any method well known in the art, for example, by initial wetting or spray drying.

[0024] The first catalyst region may extend over 100 percent of the axial length L (see, for example, Figures 1a, 1b, 3a, and 3b).

[0025] In some embodiments, the first catalyst region may extend over 50 to 95 percent of the axial length L, preferably over 60 to 90 percent, and more preferably over 70 to 90 percent (see, for example, Figures 2c and 2d). In some embodiments, the first catalyst region may extend over 30 to 70 percent of the axial length L, preferably over 40 to 60 percent, and more preferably over 45 to 55 percent (see, for example, Figures 2a, 2b, 3c and 3d).

[0026] Second catalytic region The second PGM component may further contain Pt.

[0027] The second catalytic region may further include a second oxygen storage capacity (OSC) material, a second alkali metal component or alkaline earth metal component, and / or a second inorganic oxide.

[0028] The second PGM component may be selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof. In some embodiments, the second PGM component may be Pd, Pt, or mixtures thereof.

[0029] The second OSC material can be cerium oxide, zirconium oxide, a ceria-zirconia mixed oxide, an alumina-ceria-zirconia mixed oxide, or a combination thereof. More preferably, the second OSC material includes a ceria-zirconia mixed oxide, an alumina-ceria-zirconia mixed oxide, or a combination thereof. Note that the second OSC material may further include one or more of dopants such as lanthanum, neodymium, praseodymium, yttrium, etc. Further, the second OSC material may have a function as a carrier material for the second PGM component. In some embodiments, the second OSC material includes a ceria-zirconia mixed oxide and an alumina-ceria-zirconia mixed oxide.

[0030] The ceria-zirconia mixed oxide can have a weight ratio of zirconia to ceria of at least 50:50, preferably greater than 60:40, more preferably greater than 70:30. Alternatively, the ceria-zirconia mixed oxide can also have a weight ratio of ceria to zirconia of less than 50:50, preferably less than 40:60, more preferably less than 30:70.

[0031] The second OSC material (e.g., ceria-zirconia mixed oxide) can be 10 - 90 wt%, preferably 25 - 75 wt%, more preferably 30 - 60 wt% based on the total washcoat loading of the second catalyst region.

[0032] The loading of the second OSC material in the second catalyst region can be less than 2 g / in 3 . In some embodiments, the loading of the second OSC material in the second catalyst region is 1.5 g / in 3 , 1.2 g / in 3 , 1 g / in 3 , 0.8 g / in 3 , or 0.7 g / in 3 or less.

[0033] The second alkali metal or alkaline earth metal is preferably barium, strontium, a mixed oxide or composite oxide thereof. Preferably, if present, the amount of barium or strontium is 0.1 to 15% by weight, and more preferably 3 to 10% by weight, based on the total weight of the second catalyst region.

[0034] The second alkali metal or alkaline earth metal is more preferably strontium. If present, strontium is preferably present in an amount of 0.1 to 15% by weight, and more preferably 3 to 10% by weight, based on the total weight of the second catalyst region.

[0035] Furthermore, the second alkali metal or alkaline earth metal is preferably a mixed oxide or composite oxide of barium and strontium. Preferably, the mixed oxide or composite oxide of barium and strontium is present in an amount of 0.1 to 15% by weight, and more preferably 3 to 10% by weight, based on the total weight of the second catalyst region. The second alkali metal or alkaline earth metal is more preferably a composite oxide of barium and strontium.

[0036] Preferably, barium or strontium exists as BaCO3 or SrCO3. Such materials can be produced by any method well known in the art, for example, by initial wetting or spray drying.

[0037] The second inorganic oxide is preferably an oxide of an element from Group 2, Group 3, Group 4, Group 5, Group 13, and Group 14. The second inorganic oxide is preferably selected from the group consisting of alumina, magnesia, silica, zirconia, barium oxide, and mixed or composite oxides thereof. Particularly preferred are alumina, lanthanum-alumina, zirconia, or magnesia / alumina composite oxides. One particularly preferred second inorganic oxide is alumina or lanthanum-alumina.

[0038] The second OSC material and the second inorganic oxide may have a weight ratio of 10:1 or less, preferably 8:1 or 5:1 or less, more preferably 4:1 or 3:1 or less, and most preferably 2:1 or less.

[0039] Alternatively, the second OSC material and the second inorganic oxide may have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8 or 5:1 to 1:5, more preferably 4:1 to 1:4 or 3:1 to 1:3, and most preferably 2:1 to 1:2.

[0040] In some embodiments, the second OSC material and the second inorganic oxide may have a weight ratio of 2:1 or greater. In further embodiments, the second OSC material and the second inorganic oxide may have a weight ratio of 10:1 or greater. In yet another further embodiment, the second OSC material and the second inorganic oxide may have a weight ratio of 20:1 or greater or 30:1 or greater. In yet another further embodiment, the second OSC material and the second inorganic oxide may have a weight ratio of 40:1 or greater or 50:1 or greater.

[0041] The total wash coat load in the second catalyst region is 3.5 g / in. 3 Less than 3.0 g / in 3 or 2.5g / in 3 It may be less than 0.5-3.5 g / in. Alternatively, the total wash coat load in the second catalyst region may be 0.5-3.5 g / in. 3 This may be the case, preferably 0.6 to 3 g / in 3 Or 0.7-2.5 g / in 3 It is possible.

[0042] The second catalytic region may extend over 100 percent of the axial length L (see, for example, Figures 1a and 1b).

[0043] In some embodiments, the second catalyst region may extend over 50 to 95 percent of the axial length L, preferably over 60 to 90 percent of the axial length L, and more preferably over 70 to 90 percent (see, for example, Figures 2c and 2d). In some embodiments, the second catalyst region may extend over 30 to 70 percent of the axial length L, preferably over 40 to 60 percent of the axial length L, and more preferably over 45 to 55 percent (see, for example, Figures 2a, 2b, and 3a-3d).

[0044] In some embodiments, the first catalyst region may be directly supported / deposited on the substrate. In certain embodiments, the second catalyst region may be directly supported / deposited on the substrate.

[0045] Third catalytic region The catalyst article may further include a third catalyst region.

[0046] The third catalyst region may further include a third PGM component, a third oxygen storage capacity (OSC) material, a third alkali metal component or an alkaline earth metal component, and / or a third inorganic oxide.

[0047] The third PGM component may be selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof. In further embodiments, the third PGM component may be Pd. In some embodiments, the third PGM component may be Pd, Pt, or mixtures thereof.

[0048] The third OSC material may be cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, alumina-ceria-zirconia mixed oxide, or a combination thereof. More preferably, the third OSC material includes ceria-zirconia mixed oxide, alumina-ceria-zirconia mixed oxide, or a combination thereof. The third OSC material may further contain one or more dopants such as lanthanum, neodymium, praseodymium, yttrium, etc. Furthermore, the third OSC material may function as a carrier material for the third PGM component. In some embodiments, the third OSC material includes ceria-zirconia mixed oxide and alumina-ceria-zirconia mixed oxide.

[0049] The ceria-zirconia mixed oxide may have a zirconia-to-ceria weight ratio of at least 50:50, preferably greater than 60:40, and more preferably greater than 75:25. Alternatively, the ceria-zirconia mixed oxide may also have a ceria-to-zirconia weight ratio of less than 50:50, preferably less than 40:60, and more preferably less than 25:75.

[0050] The third OSC material (e.g., ceria-zirconia mixed oxide) may be present in an amount of 10-90% by weight, preferably 25-75% by weight, and more preferably 30-60% by weight, based on the total wash coat load of the third catalyst region.

[0051] The amount of the third OSC material supported in the third catalytic region is 1.5 g / in. 3 It may be less than 1.2 g / in. In some embodiments, the amount of third OSC material supported in the second catalyst region is 1.2 g / in. 3 , 1.0g / in 3 , 0.9g / in 3 , 0.8g / in 3 , or 0.7g / in 3 The following applies:

[0052] The total wash coat load in the third catalyst region is 3.5 g / in. 3 Less than 3.0 g / in 32.5g / in 3 , or 2g / in 3 The following are possible:

[0053] The third alkali metal or alkaline earth metal is preferably barium, strontium, a mixed oxide or composite oxide thereof. Preferably, if present, the amount of barium or strontium is 0.1 to 15% by weight, and more preferably 3 to 10% by weight, based on the total weight of the third catalyst region.

[0054] The third alkali metal or alkaline earth metal is more preferably strontium. If present, strontium is preferably present in an amount of 0.1 to 15% by weight, and more preferably 3 to 10% by weight, based on the total weight of the third catalyst region.

[0055] Furthermore, the third alkali metal or alkaline earth metal is preferably a mixed oxide or composite oxide of barium and strontium. Preferably, the mixed oxide or composite oxide of barium and strontium is present in an amount of 0.1 to 15% by weight, and more preferably 3 to 10% by weight, based on the total weight of the third catalyst region. The third alkali metal or alkaline earth metal is more preferably a composite oxide of barium and strontium.

[0056] Preferably, barium or strontium exists as BaCO3 or SrCO3. Such materials can be produced by any method well known in the art, for example, by initial wetting or spray drying.

[0057] The third inorganic oxide is preferably an oxide of an element from Group 2, Group 3, Group 4, Group 5, Group 13, and Group 14. The third inorganic oxide is preferably selected from the group consisting of alumina, magnesia, silica, zirconia, barium oxide, and mixed or composite oxides thereof. Particularly preferred are alumina, lanthanum-alumina, zirconia, or magnesia / alumina composite oxides. One particularly preferred third inorganic oxide is alumina or lanthanum-alumina.

[0058] The third OSC material and the third inorganic oxide may have a weight ratio of 10:1 or less, preferably 8:1 or 5:1 or less, more preferably 4:1 or 3:1 or less, and most preferably 2:1 or less.

[0059] Alternatively, the third OSC material and the third inorganic oxide may have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8 or 5:1 to 1:5, more preferably 4:1 to 1:4 or 3:1 to 1:3, and most preferably 2:1 to 1:2.

[0060] In some embodiments, the third OSC material and the third inorganic oxide may have a weight ratio of 2:1 or greater. In further embodiments, the third OSC material and the third inorganic oxide may have a weight ratio of 10:1 or greater. In yet another further embodiment, the third OSC material and the third inorganic oxide may have a weight ratio of 20:1 or greater or 30:1 or greater. In yet another further embodiment, the third OSC material and the third inorganic oxide may have a weight ratio of 40:1 or greater or 50:1 or greater.

[0061] The third catalytic region may extend over 100 percent of the axial length L. (See, for example, Figures 3c and 3d).

[0062] In some embodiments, the third catalyst region may extend over 30 to 70 percent of the axial length L, preferably over 40 to 60 percent of the axial length L, and more preferably over 45 to 55 percent (see, for example, Figures 3a and 3b).

[0063] The catalyst article of the present invention may further contain components well known to those skilled in the art. For example, the composition of the present invention may further contain at least one binder and / or at least one surfactant. If a binder is present, a dispersible alumina binder is preferred.

[0064] Base material Preferably, the substrate is a flow-through monolith. Alternatively, the substrate may be a wall-flow filter.

[0065] The flow-through monolith substrate has a first surface and a second surface, with a longitudinal direction defined between them. The flow-through monolith substrate has a plurality of channels extending between the first surface and the second surface. The plurality of channels extend in the longitudinal direction and provide a plurality of inner surfaces (e.g., the surface of the wall defining each channel). Each of the plurality of channels has an opening on the first surface and an opening on the second surface. To avoid misunderstanding, the flow-through monolith substrate is not a wall flow filter.

[0066] The first surface is typically located at the inlet end of the substrate, and the second surface is located at the outlet end of the substrate.

[0067] The channels may have a fixed width, and each of the multiple channels may have a uniform channel width.

[0068] Preferably, in a plane perpendicular to the longitudinal direction, the monolithic substrate has 300 to 900 channels per square inch, preferably 400 to 800 channels. For example, on a first surface, the density of open first channels and closed second channels is 600 to 700 channels per square inch. The channels may have cross-sections that are rectangular, square, circular, elliptical, triangular, hexagonal, or other polygonal shapes.

[0069] The monolithic substrate acts as a support for holding the catalyst material. Suitable materials for forming the monolithic substrate include ceramic-like materials such as cordierite, silicon carbide, silicon nitride, zirconia, mullite, spodumene, alumina-silica-magnesia, or zirconium silicate, or porous heat-resistant metals. Such materials and their use in the manufacture of porous monolithic substrates are well known in the art.

[0070] It should be noted that the flow-through monolith substrate described herein is a single component (i.e., a single brick-like mass). Nevertheless, when forming an exhaust treatment system, the substrate used may be formed by bonding multiple channels together, or by bonding multiple smaller substrates together, as described herein. Such techniques, along with suitable casings and configurations for exhaust treatment systems, are well known in the art.

[0071] In embodiments of the present invention in which the catalyst article includes a ceramic substrate, the ceramic substrate may be made of any suitable heat-resistant material, such as alumina, silica, ceria, zirconia, magnesia, zeolite, silicon nitride, silicon carbide, zirconium silicate, magnesium silicate, aluminosilicate and metalloaluminosilicate (such as cordierite and spodumene), or a mixture or mixed oxide of two or more of these. Cordierite, magnesium aluminosilicate, and silicon carbide are particularly preferred.

[0072] In embodiments of the present invention in which the catalyst article includes a metal substrate, the metal substrate may be made of any suitable metal, particularly heat-resistant metals and metal alloys such as titanium and stainless steel, as well as ferrite alloys containing iron, nickel, chromium, and / or aluminum in addition to other trace metals.

[0073] Another aspect of this disclosure is the use of the catalyst articles described herein, NO xThis invention relates to a method for treating vehicle exhaust gases containing CO and HC. A catalytic converter equipped with a TWC prepared according to this method exhibits improved catalytic properties and superior catalytic properties compared to a conventional TWC (having the same PGM load) (see, for example, Examples 1 to 4, and Tables 2, 3, 5, and 7).

[0074] Another aspect of this disclosure relates to a vehicle exhaust gas treatment system, which includes a catalytic article described herein, along with conduits for transporting exhaust gases through the system.

[0075] definition As used in this invention, the term “region” typically refers to an area on a substrate obtained by drying and / or firing a wash coat. A “region” may be arranged or supported on the substrate as, for example, a “layer” or “zone.” The area or arrangement on the substrate is generally controlled during the process of applying the wash coat to the substrate. A “region” typically has a clear boundary or edge (i.e., it is possible to distinguish one region from another using conventional analytical techniques).

[0076] Typically, a “region” has substantially uniform length. In this context, “substantially uniform length” means a length that does not deviate by more than 10% from its mean (e.g., the difference between the maximum and minimum lengths), preferably a length that does not deviate by more than 5% from its mean, and more preferably a length that does not deviate by more than 1% from its mean.

[0077] Each “region” preferably has a substantially uniform composition (i.e., there is no substantial difference in the composition of the wash coat when comparing one part of the region with another part of the region). In this context, a substantially uniform composition means a material (e.g., region) in which, when comparing one part of the region with another part of the region, the difference in composition is 5% or less, usually 2.5% or less, and most commonly 1% or less.

[0078] In the present invention, the term "zone" refers to an area having a length less than the total length of the substrate, such as a length of 75% or less of the total length of the substrate. Typically, a "zone" has a length of at least 5% (e.g., 5% or more) of the total length of the substrate (i.e., a substantially uniform length).

[0079] The total length of the substrate is the distance between its inlet end and its outlet end (for example, both ends of the substrate).

[0080] Any reference to “zone located at the inlet end of the substrate” as used herein refers to a zone located or supported on the substrate such that the inlet end of the substrate is closer than the outlet end of the substrate. Thus, the midpoint of the zone (i.e., the point halfway along its length) is closer to the inlet end of the substrate than to the outlet end of the substrate. Similarly, any reference to “zone located at the outlet end of the substrate” as used herein refers to a zone located or supported on the substrate such that the outlet end of the substrate is closer than the inlet end of the substrate. Thus, the midpoint of the zone (i.e., the point halfway along its length) is closer to the outlet end of the substrate than to the inlet end of the substrate.

[0081] If the substrate is a wall flow filter, then any reference to “the zone located at the inlet end of the substrate” is generally a zone located on or supported on the substrate. (a) Zones and / or zones where the inlet end (e.g., open end) of the substrate inlet channel is closer than the closed end (e.g., blocked or sealed end) of the inlet channel. (b) A zone in which the closed end of the outlet channel of the substrate (e.g., a blocked or sealed end) is closer than the outlet end of the outlet channel (e.g., an open end).

[0082] Therefore, the midpoint of the zone (i.e., the point at half its length) is (a) closer to the inlet end of the substrate inlet channel than to the closed end of the inlet channel, and / or (b) closer to the closed end of the substrate outlet channel than to the outlet end of the outlet channel.

[0083] Similarly, if the substrate is a wall flow filter, any reference to "the zone located at the outlet end of the substrate" is a zone located on or supported on the substrate. (a) Zones and / or where the exit end (e.g., open end) of the exit channel of the substrate is closer than the closed end (e.g., blocked or sealed end) of the exit channel. (b) A zone in which the closed end of the substrate's inlet channel (e.g., a blocked or sealed end) is closer than the inlet end of the inlet channel (e.g., an open end).

[0084] Therefore, the midpoint of the zone (i.e., the point at half its length) is (a) closer to the exit end of the substrate's exit channel than to the closed end of the exit channel, and / or (b) closer to the closed end of the substrate's inlet channel than to the inlet end of the inlet channel.

[0085] If the washcoat is present on the wall of the wall flow filter (i.e., the zone is within the wall), then the zone may satisfy both (a) and (b).

[0086] The term "wash coat" is well known in the relevant technical field and typically refers to an adhesive coating applied to a substrate during the manufacturing of a catalyst.

[0087] In the present invention, the acronym "PGM, platinum group metal" refers to "platinum group metals." The term "platinum group metals" generally refers to metals selected from the group consisting of Ru, Rh, Pd, Os, Ir, and Pt, preferably metals selected from the group consisting of Ru, Rh, Pd, Ir, and Pt. Generally, the term "PGM" preferably refers to metals selected from the group consisting of Rh, Pt, and Pd.

[0088] In the present invention, the term "mixed oxide" generally refers to a mixture of oxides in a single phase, as is conventionally known in the art. In the present invention, the term "composite oxide" generally refers to a composition of oxides having two or more phases, as is conventionally known in the art.

[0089] In the present invention, the expression "consist essentially" limits the scope of the feature to include specific materials or processes, and any other materials or processes that do not materially affect the fundamental properties of the feature, such as trace impurities. The expression "consist essentially of" encompasses the expression "consisting of".

[0090] When used in the present invention with respect to materials, the expression "substantially free of" typically means that the material is present in small amounts, for example, 5% by weight or less, preferably 2% by weight or less, and more preferably 1% by weight or less, in relation to the contents of an area, layer, or zone. The expression "substantially free of" encompasses the expression "does not comprise".

[0091] When used in the present invention with respect to materials, the expression "essentially free of" typically means that the material is present in trace amounts, for example, 1% by weight or less, preferably 0.5% by weight or less, and more preferably 0.1% by weight or less, in relation to the contents of an area, layer, or zone. The expression "essentially free of" encompasses the expression "does not comprise".

[0092] In the present invention, any reference to the amount of dopant expressed as a weight percentage, particularly the total amount, refers to the weight of the carrier material or its heat-resistant metal oxide.

[0093] As used herein, the term "loading capacity" means g / ft based on the weight of the metal. 3 It refers to the measured value in that unit.

[0094] The following examples are merely illustrative of the present invention. Those skilled in the art will recognize many variations that fall within the spirit and scope of the claims of the present invention. [Examples]

[0095] Comparison catalyst A: First catalytic region: The first catalyst region consists of Rh supported on a wash coat of CeZr mixed oxide and La-stabilized alumina. The amount of Rh supported on the wash coat of the first catalyst region is approximately 1.3 g / in. 3 The Rh load is 8g / ft 3 That was the case.

[0096] Next, using a standard coating procedure, the first wash coat was applied from the exit surface of the ceramic substrate, including the second catalyst region described below, with a target total coating depth of 80% of the substrate length. The wash coat was then dried at 100°C and fired at 500°C for 45 minutes.

[0097] Second catalytic region: The second catalyst region consists of a wash coat of CeZr mixed oxide, La-stabilized alumina, and Pd supported on barium carbonate. The amount of Pd supported on the wash coat of the second catalyst region is approximately 1.8 g / in. 3 The Pd load is 42g / ft 3 That was the case.

[0098] Next, using a standard coating procedure, the wash coat was applied to the ceramic substrate from the inlet surface (600 cpsi, wall thickness 4.3 mil) with a target coating depth of 80% of the substrate length, and dried at 100°C.

[0099] The configuration of comparative catalyst A is shown in Figure 2d.

[0100] Catalyst B: The wash coat load in the second catalyst region is approximately 1.8 g / in. 3 The PD load is 38g / ft 3 The wash coat load in the first catalyst region is approximately 1.3 g / in. 3 The Rh loading capacity is 8g / ft 3 and Pt loading amount is 4g / ft 3 Catalyst B was prepared using the same procedure as comparative catalyst A, except for the fact that it was a comparative catalyst.

[0101] Catalyst C: The wash coat load in the second catalyst region is approximately 1.8 g / in. 3 The PD load is 34g / ft 3 The wash coat load in the second catalyst region is 1.3 g / in. 3 The Rh loading capacity is 8g / ft 3 and Pt loading amount is 8g / ft 3 Catalyst C was prepared using the same procedure as comparative catalyst A, except for the fact that it was a comparative catalyst.

[0102] [Table 1]

[0103] As shown in Table 1, the PGM loads in catalysts B and C were modified based on comparative catalyst A. In catalyst B, the load was 4 g / ft in the second catalytic region of comparative catalyst A. 3 Pd 4g / ft 3 The Pt was substituted, and then the Pt was rearranged in the first catalytic region. Similarly, in catalyst C, the 8 g / ft of the Pt in the second catalytic region of comparative catalyst A was used. 3 Pd 8g / ft 3 The material was substituted with Pt, and then the Pt was rearranged in the first catalyst region. These catalyst designs provide cost-effective formulations based on current PGM pricing and market trends.

[0104] Example 1: Vehicle Test Procedure and Results The latest samples of comparative catalysts A and C were tested on a 1.5-liter engine vehicle using the Worldwide Light Duty Testing Procedure (WLTP). The results of the vehicle exhaust dilution bag data are shown in Table 2.

[0105] In addition to cost reductions achieved through the inventors' catalyst formulation design, surprisingly, catalyst C of the present invention also produces NO compared to comparative catalyst A. x It showed excellent activity in emission control (for example, NO x (See the performance improvement of approximately 27%).

[0106] [Table 2]

[0107] Example 2: Procedure and results of vehicle testing The latest bench-aged samples of comparative catalyst A, as well as catalysts B and C, were tested using WLTP on a different vehicle equipped with a 1.5-liter turbo engine. Bench aging was performed under a 6.1-liter engine for the same 150 hours of operation, with a peak bed temperature of approximately 980°C in the catalyst and a 4-mode aging cycle. The results of the vehicle exhaust dilution bag data are shown in Table 3.

[0108] In addition to cost reductions achieved through the inventors' catalyst formulation design, surprisingly, catalysts B and C of the present invention produce NO compared to comparative catalyst A. x It showed excellent activity in emission control (for example, NO x (Note that performance improved by approximately 25% and 50%, respectively, compared to the latest version.) After bench aging, catalyst B still performed comparably to comparative catalyst A (with some improvement even in THC / NMHC and CO performance).

[0109] [Table 3]

[0110] Comparison catalyst D: Second catalytic region: The second catalyst region consists of a wash coat of CeZr mixed oxide, La-stabilized alumina, and Pd supported on barium carbonate. The amount of Pd supported on the wash coat of the second catalyst region is approximately 2.3 g / in. 3 The Pd load is 54g / ft 3 That was the case.

[0111] Next, using a standard coating procedure, the wash coat was applied from the entrance surface of the ceramic substrate to a target coating depth of 50% of the substrate length (600 cpsi, wall thickness 2.5 mil), dried at 100°C, and fired at 500°C for 45 minutes.

[0112] The third catalytic region: The third catalyst region consists of a wash coat of CeZr mixed oxide, La-stabilized alumina, and Pd supported on barium carbonate. The amount of Pd supported on the wash coat of the third catalyst region is approximately 2.3 g / in. 3 The Pd load is 14g / ft 3 That was the case.

[0113] Next, using a standard coating procedure, a wash coat was applied from the exit surface of the ceramic substrate, including the second catalyst region, with a target total coating depth of 50% of the substrate length. The wash coat was then dried at 100°C and fired at 500°C for 45 minutes.

[0114] First catalytic region: The first catalyst region consists of Rh supported on a wash coat of CeZr mixed oxide and La-stabilized alumina. The amount of Rh supported on the wash coat of the first catalyst region is approximately 1.5 g / in. 3 The Rh load is 6g / ft 3 That was the case.

[0115] Next, using a standard coating procedure, the first wash coat was applied from the exit surface of the ceramic substrate, including the second and third catalyst regions, with a target total coating depth of 100% of the substrate length. The wash coat was then dried at 100°C and fired at 500°C for 45 minutes.

[0116] The configuration of comparative catalyst D is shown in Figure 3a, and the coating order is the second catalyst region, the third catalyst region, and then the first catalyst region.

[0117] Catalyst E: The wash coat load in the second catalyst region is approximately 2.3 g / in. 3 The Pd load is 50g / ft 3 The wash coat load in the third catalyst region is 2.3 g / in. 3 The Pd load is 10g / ft 3 The wash coat load in the first catalyst region is 1.5 g / in. 3 The Rh loading capacity is 6g / ft 3 and Pt loading amount is 4g / ft 3 Catalyst E was prepared using the same procedure as comparative catalyst D, except for the fact that it was a comparative catalyst.

[0118] [Table 4]

[0119] As shown in Table 4, the amount of PGM supported in catalyst E was changed based on comparative catalyst D. In catalyst E, the PGM was 4 g / ft in both the second and third catalytic regions of comparative catalyst D. 3 Pd 4g / ft 3 The material was substituted with Pt, and then the Pt was rearranged in the first catalyst region. These catalyst designs provide cost-effective formulations based on current PGM pricing and market trends.

[0120] Example 3: Procedure and results of vehicle testing The latest comparative catalysts D and E were tested on a 1.5-liter engine vehicle using WLTP. The results of the vehicle exhaust dilution bag data are shown in Table 5.

[0121] In addition to cost reductions achieved through the inventors' catalyst formulation design, surprisingly, catalyst E of the present invention produces NO compared to comparative catalyst D. x It showed excellent activity in emission control (for example, NO x (See the performance improvement of approximately 36%).

[0122] [Table 5]

[0123] Comparison catalyst F: Second catalytic region: The second catalyst region consists of a wash coat of CeZr mixed oxide, La-stabilized alumina, and Pd supported on barium carbonate. The amount of wash coat supporting the second catalyst region is approximately 2.1 g / in. 3 The Pd load is 74g / ft 3 That was the case.

[0124] Next, using a standard coating procedure, the wash coat was applied from the entrance surface of the ceramic substrate to a target coating depth of 50% of the substrate length (600 cpsi, wall thickness 2.5 mil), dried at 100°C, and fired at 500°C for 45 minutes.

[0125] The third catalytic region: The third catalyst region consists of a wash coat of CeZr mixed oxide, La-stabilized alumina, and Pd supported on a barium carbonate wash coat. The amount of Pd supported on the wash coat of the third catalyst region is approximately 2.1 g / in. 3 The Pd load is 24g / ft 3 That was the case.

[0126] Next, using a standard coating procedure, a wash coat was applied from the exit surface of the ceramic substrate, including the second catalyst region, with a target total coating depth of 50% of the substrate length. The wash coat was then dried at 100°C and fired at 500°C for 45 minutes.

[0127] First catalytic region: The first catalyst region consists of Rh supported on a wash coat of CeZr mixed oxide and La-stabilized alumina. The amount of Rh supported on the wash coat of the first catalyst region is approximately 1.3 g / in. 3 The Rh load is 6g / ft 3 That was the case.

[0128] Next, using a standard coating procedure, a wash coat was applied from the exit surface of the ceramic substrate, including the second and third catalyst regions, with a target total coating depth of 100% of the substrate length. The wash coat was then dried at 100°C and fired at 500°C for 45 minutes.

[0129] The configuration of comparative catalyst F is shown in Figure 3a, and the coating order is the second catalyst region, the third catalyst region, and then the first catalyst region.

[0130] Catalyst G: The wash coat load in the first catalyst region is approximately 1.3 g / in. 3 The Rh load is 5g / ft 3 and Pt loading amount is 1g / ft 3 Except for the fact that it was a comparative catalyst, catalyst G was prepared using the same procedure as comparative catalyst F.

[0131] [Table 6]

[0132] As shown in Table 6, the amount of PGM supported in catalyst G was changed based on comparative catalyst F. In catalyst G, the PGM level was 1 g / ft in the first catalytic region of comparative catalyst F. 3 The Rh of the first catalyst region is 1 g / ft 3 It was replaced with Pt. These catalyst designs provide cost-effective formulations based on current PGM pricing and market trends.

[0133] Example 4: Procedure and results of vehicle testing Bench-aged samples of comparative catalyst F and catalyst G were separately tested using WLTP across a 1.5-liter engine vehicle. Bench-aging was performed in a 6.1-liter engine with a peak bed temperature of approximately 980°C in the catalyst, using a 4-mode aging cycle, and the same 200-hour operation period. The results of the vehicle exhaust dilution bag data for the bench-aged portions are shown in Table 7.

[0134] In addition to cost reductions achieved through the inventors' catalyst formulation design, catalyst G of the present invention still exhibited equivalent performance to comparative catalyst F for all emissions.

[0135] [Table 7]

Claims

1. A catalytic article for treating exhaust gases, A base material including an inlet end and an outlet end having an axial length L, A first catalyst region comprising a first platinum group metal (PGM) component, wherein the first PGM component comprises Rh and Pt, A second catalytic region comprising a second PGM component, wherein the second PGM component comprises a second catalytic region comprising Pd, The first PGM component has a Pt-to-Rh ratio of at least 1:20 by weight, and the first catalyst region extends over 50 to 95 percent of the axial length L. The second catalyst region extends over 50 to 95 percent of the axial length L, A catalyst article wherein the first catalyst region is provided directly on the substrate, and the second catalyst region is provided directly on the substrate.

2. The catalyst article according to claim 1, wherein the ratio of Pt in the first catalyst region to Pd in ​​the second catalyst region is at least 1:200 by weight.

3. The catalyst article according to any one of claims 1 to 2, wherein the first catalyst region further comprises a first oxygen storage capacity (OSC) material, a first inorganic oxide, or a combination thereof.

4. The catalyst article according to claim 3, wherein the first OSC material is cerium oxide, a ceria-zirconia mixed oxide, an alumina-ceria-zirconia mixed oxide, or a combination thereof.

5. The catalyst article according to claim 3 or 4, wherein the first inorganic oxide is selected from the group consisting of oxides of alumina, magnesia, silica, zirconia, lanthanum, neodymium, praseodymium, or yttrium, and mixed oxides or composite oxides thereof.

6. The catalyst article according to any one of claims 1 to 5, wherein the second catalyst region further comprises a second OSC material, a second inorganic oxide, or a combination thereof.

7. The catalyst article according to claim 6, wherein the second OSC material is cerium oxide, a ceria-zirconia mixed oxide, an alumina-ceria-zirconia mixed oxide, or a combination thereof.

8. The catalyst article according to claim 6 or 7, wherein the second inorganic oxide is selected from the group consisting of oxides of alumina, magnesia, silica, zirconia, lanthanum, cerium, neodymium, praseodymium, or yttrium, and mixed oxides or composite oxides thereof.

9. The catalyst article according to claim 2, wherein the ratio of Pt in the first catalyst region to Pd in ​​the second catalyst region is 200:1 to 1:

200.

10. The catalyst article according to any one of claims 1 to 9, wherein the first PGM component has a Pt-to-Rh ratio of 20:1 to 1:

20.

11. A catalyst article according to any one of claims 1 to 10, further comprising a third catalyst region.

12. The catalyst article according to claim 11, wherein the third catalyst region contains a third PGM component.

13. The catalyst article according to claim 12, wherein the third PGM component is selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof.

14. The catalyst article according to claim 13, wherein the third PGM component comprises Pd.

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