Catalysts for gasoline exhaust treatment with improved ammonia emission control

Abstract

A three-way catalyst article having improved ammonia emission control and its use in an exhaust system for a gasoline engine is disclosed. A catalyst article for treating exhaust gas from a gasoline engine, the catalyst article comprising: a substrate including an inlet end and an outlet end having an axial length L; a first catalyst region beginning at the inlet end, the first catalyst region comprising a first zeolite; and a second catalyst region beginning at the outlet end, the second catalyst region comprising a second platinum group metal (PGM) component, a second oxygen storage capacity (OSC) material, and a second inorganic oxide, the second PGM component being selected from the group consisting of palladium, platinum, rhodium, and combinations thereof.

Description

[Technical field]

[0001] The present invention relates to catalytic articles useful for treating exhaust gas emissions from gasoline engines. [Background technology]

[0002] In internal combustion engines, the main components of the exhaust gas are hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxide (NO x ) are produced in the exhaust gas. Emissions control systems that include exhaust gas catalytic conversion catalysts are widely used to reduce the amount of these pollutants emitted into the atmosphere. The catalyst typically used to treat exhaust from gasoline engines is the three way catalyst (TWC). TWCs perform three main functions: (1) oxidation of CO, (2) oxidation of unburned HC, and (3) oxidation of NO. x However, ammonia (NH3) can be reduced to NO using the TWC. x It has been recognized that NH3 is a by-product of the reduction of NH3. Therefore, NH3 may pose new pollutant emission problems, such as secondary inorganic aerosol formation, which may lead to poor air quality. Future emission control legislation is expected to limit NH3 emissions from gasoline engines.

[0003] To meet future regulations and keep NH3 emissions under control, other researchers have attempted to use ammonia slip catalyst (ASC), a typical emission control approach in heavy duty diesel (HDD) aftertreatment systems. However, due to different compositions in fuel sources (diesel vs. gasoline) and different operating conditions (lean vs. stoichiometric), typical ASC designs do not work at all for NH3 emission control for stoichiometric gasoline engines. Therefore, there remains a need for improved NH3 emission control catalysts specifically designed to treat exhaust gas emissions from stoichiometric gasoline engines. Summary of the Invention

[0004] One aspect of the disclosure relates to a catalyst article for treating exhaust gas from a gasoline engine, the catalyst article comprising: a substrate having an inlet end, an outlet end, the substrate having an axial length L; a first catalyst region beginning at the inlet end, the first catalyst region comprising a first zeolite; and a second catalyst region beginning at the outlet end, the second catalyst region comprising a second platinum group metal (PGM) component, a second oxygen storage capacity (OSC) material, and a second inorganic oxide, the second PGM component being selected from the group consisting of palladium, platinum, rhodium, and combinations thereof.

[0005] The present invention also includes an emission system for a gasoline engine which includes the catalyst article of the present invention.

[0006] The present invention also encompasses treating exhaust gas from a gasoline engine, the method comprising contacting the exhaust gas with a catalytic article of the present invention. [Brief description of the drawings]

[0007] [Figure 1]1 shows an embodiment according to the invention in which a first catalyst region extends 100% of the axial length L as a top layer and a second catalyst region extends 100% of the axial length L as a bottom layer. [Figure 2a] 1 illustrates an embodiment according to the present invention in which the first catalyst region extends from the inlet end less than 100% of the axial length L, and the second catalyst region extends from the outlet end less than 100% of the axial length L. The total length of the second catalyst region and the first catalyst region is equal to the axial length L. [Figure 2b] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends from the inlet end less than 100% of the axial length L, and a second catalyst region extends from the outlet end 100% of the axial length L. The total length of the second catalyst region and the first catalyst region is greater than the axial length L. [Figure 2c] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends from the inlet end less than 100% of the axial length L, and a second catalyst region extends from the outlet end 100% of the axial length L. The total length of the second catalyst region and the first catalyst region is greater than the axial length L. [Figure 2d] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends from the inlet end less than 100% of the axial length L, and a second catalyst region extends from the outlet end less than 100% of the axial length L. The total length of the second catalyst region and the first catalyst region is less than the axial length L. [Figure 3a] 1 illustrates an embodiment according to the present invention, where a first catalyst region extends less than 100% of the axial length L from the inlet end and a second catalyst region extends less than 100% of the axial length L from the outlet end. The total length of the second catalyst region and the first catalyst region is equal to the axial length L. A third catalyst region extends less than 100% of the axial length L from the outlet end. [Figure 3b] 1 shows an embodiment according to the invention in which a first catalyst region is a top layer extending over 100% of the axial length L, a second catalyst region is a bottom layer extending over 100% of the axial length L, and a third catalyst region is a middle layer extending over 100% of the axial length L. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention relates to the catalytic treatment of exhaust gases, such as those produced by stoichiometric CNG engines, and related catalyst articles and systems. More specifically, the present invention relates to the control of ammonia emissions and the reduction of NOx in vehicle exhaust systems. x , CO, and HC simultaneous treatment.

[0009] One aspect of the disclosure relates to a catalyst article for treating exhaust gas from a gasoline engine, the catalyst article comprising: a substrate having an inlet end, an outlet end, the substrate having an axial length L; a first catalyst region beginning at the inlet end, the first catalyst region comprising a first zeolite; and a second catalyst region beginning at the outlet end, the second catalyst region comprising a second platinum group metal (PGM) component, a second oxygen storage capacity (OSC) material, and a second inorganic oxide, the second PGM component being selected from the group consisting of palladium, platinum, rhodium, and combinations thereof.

[0010] The first catalytic region The first zeolite may be a silica-containing zeolite, such as a siliceous zeolite, also referred to as an aluminosilicate zeolite, a metal-substituted aluminosilicate zeolite, an aluminophosphate (AIPO) zeolite, a metal-substituted (MeAIPO) zeolite, a silico-aluminophosphate (SAPO), or a metal-substituted silicoaluminophosphate (MeAPSO), or a modified zeolite with Zr, P. The zeolite is preferably an aluminosilicate or a silicoaluminophosphate (SAPO) zeolite. More preferably, the zeolite is an aluminosilicate.

[0011] The zeolite may be a microporous or non-microporous zeolite, preferably the zeolite has a framework type selected from the group consisting of ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, AST, ASV, ATT, BCT, BEA, BEC, BOF, BOG, BRE, CAN, CDO, CFI, CGS, CHA, CHI, CON, DAC, DDR, DFT, EAB, EDI, EPI, ERI, FER, GIS, GOD, IHW, ITE, ITW, LEV, KFI, MER, MFI, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON. Each of the aforementioned three letter codes represents a framework type according to the structure of the "IUPAC Commission on zeolite Nomenclature" and / or the Commission of the international Zeolite Association. More preferably, the first zeolite has a framework type selected from AEI, BEA, CHA, FER, FAU, MFA, or LEV. In some embodiments, the first zeolite can be AEI, BEA, FER, LEV, or CHA. In further embodiments, the first zeolite can be LEV, FER, CHA, or AEI. In still further embodiments, the first zeolite can be FER, AEI, or CHA. In another further embodiment, the first zeolite can be FER. In another further embodiment, the first zeolite can be AEI. In another further embodiment, the first zeolite can be CHA. Generally, the first zeolite can have a silica-to-alumina ratio (SAR) of 2-500, preferably 4-250, more preferably 8-150. In some embodiments, the first zeolite is FER or CHA or AEI with a SAR range of 8-40. In a further embodiment, the first zeolite is FER or CHA or AEI having a SAR range of 10-30.

[0012] In certain embodiments, the first catalyst region may further comprise a first transition metal, which may be selected from the group consisting of Fe, Cu, Co, Mn, Ni, Zn, Ce, Mo, Ag, and any combination of two or more. In further embodiments, the first transition metal may be selected from Ce, Mn, Cu, Co, Ni, or Fe, and any combination of two or more. In yet other embodiments, the first transition metal may be Cu and / or Fe. In certain embodiments, the first transition metal is present in an amount of 0.01-20 wt%, preferably 0.1-15 wt%, more preferably 0.5-10 wt% based on the weight of the first zeolite, and even more preferably 1-9 wt% or 2-8 wt% based on the weight of the first zeolite.

[0013] In certain embodiments, the first catalyst region may extend over 100% of the axial length L. In other embodiments, the first catalyst region may extend over 30-90%, 40-80%, or 40-60% of the axial length L. Alternatively, the first catalyst region may extend over 30-80% or 30-70% of the axial length L.

[0014] The total washcoat loading of the first catalyst region was 3.5 g / in 3 Less than 3.0 g / in 3 Less than or equal to 2.5g / in 3 Alternatively, the total washcoat loading of the first catalyst region may be between 0.5 and 3.5 g / in 3 and preferably, 0.6 to 3 g / in 3 Or 0.7~2.8g / in 3 may be also possible.

[0015] The second catalytic region In some embodiments, the second PGM component can be Pd and Rh. In other embodiments, the second PGM component can be Pt and Rh. In yet another embodiment, the second PGM component can be Pt.

[0016] The second OSC material may be cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, alumina-ceria-zirconia mixed oxide, or a combination thereof. More preferably, the second OSC material includes ceria-zirconia mixed oxide, alumina-ceria-zirconia mixed oxide, or a combination thereof. In addition, the second OSC material may further include one or more of dopants such as lanthanum, neodymium, praseodymium, yttrium, etc. Furthermore, the second OSC material may function as a support material for the second PGM component. In some embodiments, the second OSC material includes ceria-zirconia mixed oxide and alumina-ceria-zirconia mixed oxide.

[0017] The ceria-zirconia mixed oxide may have a weight ratio of zirconia dioxide to ceria dioxide of at least 50:50, preferably greater than 60:40, more preferably greater than 65:35. Alternatively, the ceria-zirconia mixed oxide may also have a weight ratio of ceria dioxide to zirconia dioxide less than 50:50, preferably less than 40:60, more preferably less than 35:65.

[0018] The second OSC material (eg, ceria-zirconia mixed oxide) can be 10-90 wt %, preferably 20-90 wt %, more preferably 30-90 wt %, based on the total washcoat loading of the second catalyst region.

[0019] The loading of the second OSC material in the second catalyst region is 2 g / in 3 In some embodiments, the loading of the second OSC material in the second catalytic region can be less than 2 g / in 3 Below 1.5g / in 3 Below, 1.2g / in 3 Below, 1.0g / in 3 or less than 0.8g / in 3 The following is the result.

[0020] The second inorganic oxide is preferably an oxide of an element of 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, zirconia, magnesia, silica, lanthanum, yttrium, neodymium, praseodymium oxides, and mixed oxides or composite oxides thereof. Particularly preferably, the second inorganic oxide is alumina, lanthanum-alumina, zirconia, or magnesia / alumina composite oxide. One particularly preferred second inorganic oxide is alumina or lanthanum-alumina.

[0021] The second OSC material and the second inorganic oxide may have a weight ratio of 10:1 or less, preferably 8:1 or less, more preferably 5:1 or less, and most preferably 4:1 or less.

[0022] Alternatively, the second OSC material and the second inorganic oxide can have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8, more preferably 5:1 to 1:5, and most preferably 4:1 to 1:4.

[0023] In some embodiments, the second catalytic region may not further comprise a second alkali metal or alkaline earth metal.

[0024] The second alkali or alkaline earth metal is preferably barium, strontium, a mixed oxide or a composite oxide thereof. Preferably, the barium or strontium, if present, is in an amount of 0.1 to 15 wt. %, more preferably 3 to 10 wt. %, barium or strontium, based on the total weight of the second catalytic region.

[0025] Preferably, the barium or strontium is present as BaCO3 or SrCO3. Such materials can be prepared by any method known in the art, such as incipient wetness impregnation or spray drying.

[0026] In some embodiments, the second catalytic region is substantially free of a second alkali metal or alkaline earth metal. In further embodiments, the second catalytic region is substantially free or free of a second alkali metal or alkaline earth metal.

[0027] In certain embodiments, the first catalyst region may extend over 100% of the axial length L. In other embodiments, the second catalyst region may extend over 30-90%, 40-80%, or 40-70% of the axial length L. Alternatively, the second catalyst region may extend over 40-90%, preferably 45-60% of the axial length L. Alternatively, the second catalyst region may extend over 90% or less, 85% or less, 80% or less, or 75% or less of the axial length L.

[0028] In some embodiments, the second catalyst region may overlap the first catalyst region. In further embodiments, the second catalyst region may overlap the first catalyst region over 5-40% of the axial length L. Preferably, the total length of the second region and the first region may be equal to or less than the axial length L. In certain embodiments, the total length of the first catalyst region and the second catalyst region is equal to 100% L. In other embodiments, the total length of the first catalyst region and the second catalyst region is less than 100% L, for example, 99% or less, 95% or less, 85% or less, or 80% or less of the axial length L.

[0029] In certain embodiments, the second catalytic region may be supported / deposited directly on the substrate.

[0030] The total washcoat loading of the second catalyst region was 3.5 g / in 3 Less than 3.0 g / in 3 Less than or equal to 2.5g / in 3 Alternatively, the total washcoat loading of the second catalyst region may be between 0.5 and 3.5 g / in 3 and preferably 0.6 to 3.5 g / in 3 Or 0.7 to 3.0 g / in 3 may be also possible.

[0031] The third catalytic area The catalyst article may further include a third catalyst region. In some embodiments, the third catalyst region may begin at the outlet end. In further embodiments, the third catalyst region may extend across the axial length L. In other embodiments, the third catalyst region may extend across less than 100% of the axial length L.

[0032] The third catalyst region may further comprise a third PGM component, a third oxygen storage capacity (OSC) material, a third alkali metal or alkaline earth metal component, and / or a third inorganic oxide.

[0033] The third PGM component may be selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof. In some embodiments, the third PGM component may be palladium, rhodium, or mixtures thereof. In other embodiments, the third PGM component may be platinum, rhodium, or mixtures thereof.

[0034] 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. In addition, the third OSC material may further include one or more of dopants such as lanthanum, neodymium, praseodymium, yttrium, etc. Furthermore, the third OSC material may function as a support material for the third PGM component. In some embodiments, the third OSC material includes ceria-zirconia mixed oxide and alumina-ceria-zirconia mixed oxide.

[0035] The ceria-zirconia mixed oxide may have a weight ratio of zirconia dioxide to ceria dioxide of at least 50:50, preferably greater than 60:40, more preferably greater than 65:35. Alternatively, the ceria-zirconia mixed oxide may also have a weight ratio of ceria dioxide to zirconia dioxide less than 50:50, preferably less than 40:60, more preferably less than 35:65.

[0036] The third OSC material (eg, 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 third catalyst region.

[0037] The loading of the third OSC material in the third catalytic region is 2 g / in 3 In some embodiments, the loading of the third OSC material in the second catalytic region can be less than 2.0 g / in 3 Below 1.5g / in 3 Below, 1.2g / in 3 Below, 1.0g / in 3 or less than 0.8g / in 3 The following is the result.

[0038] The total washcoat loading of the third catalyst region was 3.5 g / in 3 Less than 3.0 g / in 3 Below 2.5g / in 3 Less than or equal to 2g / in 3 It can be the following:

[0039] The third alkali or alkaline earth metal is preferably barium, strontium, a mixed oxide or a composite oxide thereof. Preferably, the barium or strontium, if present, is in an amount of 0.1 to 15 wt. %, more preferably 3 to 10 wt. %, barium or strontium, based on the total weight of the third catalytic region.

[0040] Even more preferably, the third alkali or alkaline earth metal is barium. When present, barium is preferably present in an amount of from 0.1 to 15% by weight, more preferably from 3 to 10% by weight, based on the total weight of the third catalytic region.

[0041] Also, 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, more preferably 3 to 10% by weight, based on the total weight of the third catalytic region. More preferably, the third alkali metal or alkaline earth metal is a composite oxide of barium and strontium.

[0042] Preferably, the barium or strontium is present as BaCO3 or SrCO3. Such materials can be prepared by any method known in the art, such as incipient wetness impregnation or spray drying.

[0043] In some embodiments, the third catalytic region is substantially free of a third alkali metal or alkaline earth metal. In further embodiments, the third catalytic region is substantially free or free of a third alkali metal or alkaline earth metal.

[0044] The third inorganic oxide is preferably an oxide of an element of 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, zirconia, magnesia, silica, lanthanum, neodymium, praseodymium, yttrium oxides, and mixed oxides or composite oxides thereof. Particularly preferably, the third inorganic oxide is alumina, lanthanum-alumina, zirconia, or magnesia / alumina composite oxide. One particularly preferred third inorganic oxide is alumina or lanthanum-alumina.

[0045] The third OSC material and the third inorganic oxide can have a weight ratio of 10:1 or less, preferably 8:1 or less or 5:1 or less, more preferably 5:1 or less, and most preferably 4:1 or less.

[0046] Alternatively, the third OSC material and the third inorganic oxide can have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8, or more preferably 5:1 to 1:5, or most preferably 4:1 to 1:4.

[0047] The third catalytic region can extend over 100% of the axial length L. (See, e.g., FIG. 3b.) Alternatively, the third catalytic region can extend over less than the axial length L, e.g., 95% or less, 90% or less, 80% or less, or 70% or less of the axial length L. (See, e.g., FIG. 3a.)

[0048] Base material Preferably, the substrate is a flow-through monolith.

[0049] The substrate can be less than 8 inches in length, preferably 2 to 6 inches.

[0050] The flow-through monolith substrate has a first surface and a second surface defining a longitudinal direction therebetween. The flow-through monolith substrate has a plurality of channels extending between the first surface and the second surface. The plurality of channels extend longitudinally and provide a plurality of interior surfaces (e.g., surfaces of walls defining each channel). Each of the plurality of channels has an opening at the first surface and an opening at the second surface. For the avoidance of doubt, the flow-through monolith substrate is not a wall-flow filter.

[0051] The first surface is typically at an inlet end of the substrate and the second surface is at an outlet end of the substrate.

[0052] The channels may be of constant width, and each of the multiple channels may have a uniform channel width.

[0053] Preferably, in a plane perpendicular to the longitudinal direction, the monolith substrate has 300 to 900 channels per square inch, preferably 400 to 800 channels per square inch. For example, on the first face, 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, oval, triangular, hexagonal, or other polygonal shapes.

[0054] The monolith substrate acts as a support to hold the catalytic material. Suitable materials for forming the monolith substrate include ceramic-like materials such as cordierite, silicon carbide, silicon nitride, zirconia, mullite, spodumene, alumina-silica magnesia or zirconium silicate, or porous refractory metals. Such materials and their use in the manufacture of porous monolith substrates are well known in the art.

[0055] It should be noted that the flow-through monolith substrates described herein are unitary components (i.e., a single brick-like mass). Nevertheless, when forming an emission treatment system, the substrates used may be formed by bonding together multiple channels, or by bonding together multiple smaller substrates as described herein. Such techniques, along with suitable casings and configurations of emission treatment systems, are well known in the art.

[0056] In embodiments in which the catalytic article of the present invention includes a ceramic substrate, the ceramic substrate may be made of any suitable refractory material, such as alumina, silica, ceria, zirconia, magnesia, zeolites, silicon nitride, silicon carbide, zirconium silicate, magnesium silicate, aluminosilicates and metalloid aluminosilicates (such as cordierite and spodumene), or mixtures or mixed oxides of any two or more thereof. Cordierite, magnesium aluminosilicate, and silicon carbide are particularly preferred.

[0057] In embodiments in which the catalytic article of the present invention 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, and ferritic alloys containing iron, nickel, chromium, and / or aluminum in addition to other trace metals.

[0058] In some embodiments, the first catalytic region may be located on a different substrate than the second (or optionally the third) catalytic region.

[0059] Another aspect of the present disclosure is a method for producing a NO x The present invention relates to a method for treating vehicle exhaust gas from a gasoline engine, which contains CO, HC, and ammonia. The test catalysts made according to the present invention showed significantly improved NH3 control performance compared to conventional TWC (see, for example, Example 4, and Examples 9 and 10).

[0060] Another aspect of the present disclosure relates to a system for treating vehicle exhaust gases that includes a catalytic article as described herein along with a conduit for transporting the exhaust gases through the system.

[0061] In some embodiments, the system may further include a TWC article. In further embodiments, the TWC article is upstream of the catalyst article of the first aspect. In certain embodiments, the TWC article and the catalyst article upstream of the first aspect may be on different substrates. In other embodiments, the TWC article and the catalyst article upstream of the first aspect may be on the same substrate.

[0062] definition The term "region" as used herein refers to an area on a substrate that is typically obtained by drying and / or firing a washcoat. A "region" can be disposed or carried on a substrate as, for example, a "layer" or a "zone." The area or arrangement on the substrate is generally controlled during the process of applying the washcoat to the substrate. A "region" typically has a distinct boundary or edge (i.e., it is possible to distinguish one region from another using conventional analytical techniques).

[0063] Typically, a "region" has a substantially uniform length. Reference to a "substantially uniform length" in this context refers to a length that does not deviate from its average value by more than 10% (e.g., the difference between the maximum and minimum length), preferably a length that does not deviate from its average value by more than 5%, and more preferably a length that does not deviate from its average value by more than 1%.

[0064] Each "region" preferably has a substantially uniform composition (i.e., there is no substantial difference in the composition of the washcoat when comparing one portion of the region to another portion of the region). Substantially uniform composition in this context refers to a material (e.g., region) that has a compositional difference of 5% or less, usually 2.5% or less, and most usually 1% or less, when comparing one portion of the region to another portion of the region.

[0065] As used herein, the term "zone" refers to a region having a length that is less than the entire length of the substrate, such as a length that is 75% or less of the entire length of the substrate. A "zone" typically has a length that is at least 5% (e.g., 5% or more) of the entire length of the substrate (i.e., a substantially uniform length).

[0066] The overall length of a substrate is the distance between its inlet end and its outlet end (eg, both ends of the substrate).

[0067] Any reference herein to a "zone disposed at the inlet end of a substrate" refers to a zone disposed on or supported by a substrate, which is closer to the inlet end of the substrate than to the outlet end of the substrate. Thus, the midpoint of the zone (i.e., a point at half its length) is closer to the inlet end of the substrate than to the outlet end of the substrate. Similarly, any reference herein to a "zone disposed at the outlet end of a substrate" refers to a zone disposed on or supported by a substrate, which is closer to the outlet end of the substrate than to the inlet end of the substrate. Thus, the midpoint of the zone (i.e., a point at half its length) is closer to the outlet end of the substrate than to the inlet end of the substrate.

[0068] When the substrate is a wall-flow filter, generally any reference to "a zone disposed at the inlet end of the substrate" refers to a zone disposed on or supported by the substrate, (a) a zone that is closer to the inlet end (e.g., an open end) of an inlet channel of the substrate than to the closed end (e.g., a blocked or plugged end) of the inlet channel; and / or (b) Refers to a zone that is closer to the closed end (e.g., blocked or plugged end) of an outlet channel of a substrate than to the outlet end (e.g., open end) of the outlet channel.

[0069] Thus, the midpoint of the zone (i.e., the point at half its length) is (a) closer to the inlet end of the inlet channel of the substrate than to the closed end of the inlet channel, and / or (b) closer to the closed end of the outlet channel of the substrate than to the outlet end of the outlet channel.

[0070] Similarly, where the substrate is a wall-flow filter, any reference to a "zone disposed at the outlet end of the substrate" refers to a zone disposed on or carried by the substrate, (a) a zone that is closer to the outlet end (e.g., an open end) of the outlet channel of the substrate than to the closed end (e.g., a blocked or plugged end) of the outlet channel; and / or (b) Refers to a zone that is closer to the closed end (e.g., blocked or plugged end) of an inlet channel of a substrate than to the inlet end (e.g., open end) of the inlet channel.

[0071] Thus, the midpoint of the zone (i.e., the point at half its length) is (a) closer to the outlet end of the outlet channel of the substrate than to the closed end of the outlet channel, and / or (b) closer to the closed end of the inlet channel of the substrate than to the inlet end of the inlet channel.

[0072] If a washcoat is present on the wall of a wall-flow filter (ie, the zone is within the wall), the zone may satisfy both (a) and (b).

[0073] The term "washcoat" is well known in the art and typically refers to an adherent coating that is applied to a substrate during the production of a catalyst.

[0074] The acronym "PGM" as used herein 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. In general, the term "PGM" preferably refers to metals selected from the group consisting of Rh, Pt, and Pd.

[0075] The term "mixed oxide" as used herein generally refers to a mixture of oxides in a single phase, as is conventionally known in the art. The term "complex oxide" as used herein generally refers to a composition of oxides having two or more phases, as is conventionally known in the art.

[0076] As used herein, the phrase "consisting essentially of" limits the scope of a feature to include the specified materials or steps and any other materials or steps, e.g., trace impurities, that do not substantially affect the basic properties of the feature. "Consisting essentially of" encompasses the phrase "consisting of."

[0077] As used herein with respect to a material, the term "substantially free" typically means that the material is present in a small amount, e.g., 5% by weight or less, preferably 2% by weight or less, more preferably 1% by weight or less, in relation to the contents of a region, layer, or zone. The term "substantially free" encompasses the term "free."

[0078] As used herein with respect to a material, the term "essentially free" typically means that the material is present in trace amounts, e.g., 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.1% by weight or less, in the context of the contents of a region, layer, or zone. The term "essentially free" encompasses the term "free."

[0079] As used herein, any reference to an amount of dopant expressed as weight percent, particularly a total amount, refers to the weight of the support material or its refractory metal oxide.

[0080] As used herein, the term "loading" refers to g / ft2 on a metal weight basis. 3 Refers to the measurement in units of .

[0081] The following examples are merely illustrative of the present invention, and those skilled in the art will recognize many variations that are within the spirit and scope of the claims. EXAMPLES

[0082] material All materials are commercially available and were obtained from known sources unless otherwise stated.

[0083] Catalyst A A catalyst was prepared with a single layer of Fe supported on a FER type zeolite with an SAR range of about 17 and a binder, with a total washcoat loading of about 1.6 g / in. 3 and the Fe loading was about 3 wt % (based on the weight of FER).

[0084] The washcoat was coated onto the ceramic substrate (400 cpsi, 4 mil wall thickness) using standard coating procedures.

[0085] Catalyst B A catalyst was prepared with a single layer of AEI type zeolite with an SAR range of about 20 and a binder, with a total washcoat loading of about 1.6 g / in 3 It was.

[0086] The washcoat was coated onto the ceramic substrate (400 cpsi, 4 mil wall thickness) using standard coating procedures.

[0087] Catalyst C A catalyst with a single layer was prepared. The layer consisted of AEI type zeolite with an SAR range of about 20 and Cu supported on a binder, with a total washcoat loading of about 1.6 g / in. 3 and the Cu loading was about 2 wt % (based on the weight of AEI).

[0088] The washcoat was coated onto the ceramic substrate (400 cpsi, 4 mil wall thickness) using standard coating procedures.

[0089] Catalyst D A catalyst with a single layer was prepared. The layer consisted of AEI type zeolite with an SAR range of about 17 and Cu supported on a binder, with a total washcoat loading of about 1.6 g / in. 3 and the Cu loading was about 4 wt % (based on the weight of AEI).

[0090] The washcoat was coated onto the ceramic substrate (400 cpsi, 4 mil wall thickness) using standard coating procedures.

[0091] Example 1 - NH3 absorption test Catalysts A to D were aged at 850° C. for 4 hours under the hydrocarbon (HC) oxidation-reduction conditions shown in Table 1.

[0092] [Table 1]

[0093] After HC redox aging, catalysts A-D were tested for their NH3 storage performance under the test protocol as shown in Table 2.

[0094] [Table 2]

[0095] As shown in Table 3 below, catalyst B exhibits its NH3 storage capacity, whereas catalysts A, C, and D exhibit superior / improved NH3 storage capacity when compared to catalyst B.

[0096] [Table 3]

[0097] Example 2 - High temperature NH3 conversion with stoichiometric NH3 supply After HC redox aging, catalysts A-D were tested for their high temperature NH3 conversion performance under the test protocol as shown in Table 4.

[0098] [Table 4]

[0099] As shown in Table 5 below, catalysts A, C, and D showed good NH3 and NO conversions under stoichiometric feed conditions.

[0100] [Table 5]

[0101] Example 3 - High temperature NH3 conversion with rich NH3 feed Catalysts A and D were aged at 850° C. for 4 hours under different conditions as shown in Table 6.

[0102] [Table 6]

[0103] After aging, catalysts A and D were tested for their high temperature NH3 conversion performance under the test protocol as shown in Table 7.

[0104] [Table 7]

[0105] As shown in Table 8 below, catalysts A and D showed good NH3 and NO conversions under rich feed conditions.

[0106] [Table 8]

[0107] TWC-1 TWC-1 is a typical ternary (Pd-Rh) catalyst with a double-layer structure in the two catalytic regions, as shown in Figure 1. The bottom layer consists of Pd supported on a first CeZr mixed oxide, La-stabilized alumina, and Ba-promoter washcoat. The washcoat loading of the bottom layer is about 2.0 g / in. 3 The Pd loading is 16 g / ft 3Using standard coating procedures, the washcoat was coated (400 cpsi, 4.3 mil wall thickness) from each end face of the ceramic substrate with a targeted coating depth of 50% of the substrate length, dried at 100° C., and fired at 500° C. for 45 minutes.

[0108] The top layer is made of a second CeZr mixed oxide, Rh supported on a washcoat of La-stabilized alumina. The washcoat loading of the second layer is about 1.5 g / in 3 The Rh loading is 4g / ft 3 This second washcoat was then coated from each end face of the ceramic substrate containing the bottom layer using standard coating procedures with a coating depth targeted to be 50% of the substrate length, dried at 100°C, and fired at 500°C for 45 minutes.

[0109] TWC-2 TWC-2 is a typical ternary (Pd-Rh) catalyst with a single-layer structure. The catalyst layer consists of Pd and Rh supported on a first CeZr mixed oxide, La-stabilized alumina, and a Ba-promoter washcoat. The washcoat loading of the layer is about 3.0 g / in. 3 The Pd loading is 2 g / ft 3 The Rh loading is 8 g / ft 3 Using standard coating procedures, the washcoat was coated (400 cpsi, 4.3 mil wall thickness) from each end face of the ceramic substrate with a targeted coating depth of 50% of the substrate length, dried at 100° C., and fired at 500° C. for 45 minutes.

[0110] Catalyst article 1 A catalyst with two catalytic regions was prepared (see, for example, FIG. 2a).

[0111] The first catalytic region The first catalytic region is comprised of Fe supported on a FER type zeolite with an SAR range of about 16-20 and a binder, with a total washcoat loading of about 1.5 g / in3 and the Fe loading was about 3 wt % (based on the weight of FER).

[0112] The first catalyst region was washcoated from the inlet end face of the ceramic substrate using standard coating procedures with a coating depth targeted to be 50% of the substrate length (400 cpsi, 4.3 mil wall thickness).

[0113] The second catalytic region The washcoat of the second catalytic region consisted of La-alumina, ceria-zirconia mixed oxide, platinum, and rhodium (approximately 3.0 g / in 3 , Pt loading is 6.7g / ft 3 The Rh loading is 3.3 g / ft 3 A washcoat was applied from the outlet end face of the ceramic substrate containing the first catalytic region using standard coating procedures with a coating depth targeted to be 50% of the substrate length.

[0114] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0115] Catalyst article 2 A catalyst with two catalytic regions was prepared (see, for example, FIG. 2a).

[0116] The first catalytic region The first catalytic region is comprised of Fe supported on a FER type zeolite with an SAR range of about 16-20 and a binder, with a total washcoat loading of about 1.5 g / in 3 and the Fe loading was about 3 wt % (based on the weight of FER).

[0117] The first catalyst region was washcoated from the inlet end face of the ceramic substrate using standard coating procedures with a coating depth targeted to be 50% of the substrate length (400 cpsi, 4.3 mil wall thickness).

[0118] The second catalytic region The washcoat of the second catalytic region was composed of La-alumina, ceria-zirconia mixed oxide, platinum (approximately 3.0 g / in 3 , Pt loading is 10g / ft 3 A washcoat was applied from the outlet end face of the ceramic substrate containing the first catalytic region using standard coating procedures with a coating depth targeted to be 50% of the substrate length.

[0119] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0120] Catalyst article 3 A catalyst with two catalytic regions was prepared (see, for example, FIG. 2a).

[0121] The first catalytic region The first catalytic region is comprised of Fe supported on a FER type zeolite with an SAR range of about 16-20 and a binder, with a total washcoat loading of about 1.5 g / in 3 and the Fe loading was about 3 wt % (based on the weight of FER).

[0122] The first catalyst region was washcoated from the inlet end face of the ceramic substrate using standard coating procedures with a coating depth targeted to be 50% of the substrate length (400 cpsi, 4.3 mil wall thickness).

[0123] The second catalytic region The washcoat of the second catalytic region consisted of La-alumina, ceria, platinum, and rhodium (approximately 3.0 g / in 3 , Pt loading is 6.7g / ft 3 The Rh loading is 3.3 g / ft 3 A washcoat was applied from the outlet end face of the ceramic substrate containing the first catalytic region using standard coating procedures with a coating depth targeted to be 50% of the substrate length.

[0124] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0125] Catalyst article 4 A catalyst having two catalytic regions was prepared (see, for example, FIG. 1).

[0126] The first catalytic region The first catalytic region is comprised of Fe supported on a FER type zeolite with an SAR range of about 16-20 and a binder, with a total washcoat loading of about 1.5 g / in 3 and the Fe loading was about 3 wt % (based on the weight of FER).

[0127] Using standard coating procedures, the first catalyst region washcoat was coated (400 cpsi, 4.3 mil wall thickness) from both the inlet and outlet end faces of the ceramic substrate with a coating depth targeted to 50% of the length of the substrate, covering the entire ceramic substrate.

[0128] The second catalytic region The washcoat of the second catalytic region consisted of La-alumina, ceria-zirconia mixed oxide, platinum, and rhodium (approximately 3.0 g / in 3 , Pt loading is 6.7g / ft 3 The Rh loading is 3.3 g / ft 3 Using standard coating procedures, the second catalyst region washcoat was coated (400 cpsi, 4.3 mil wall thickness) from both the inlet and outlet end faces of the ceramic substrate with a coating depth targeted to 50% of the substrate length, covering all of the ceramic substrate.

[0129] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0130] Catalytic performance tests were carried out using synthetic exhaust gas and catalyst samples were aged at 800° C. for 10 hours in 10% water, 5% O2, balance N2.

[0131] Catalyst article 5 A catalyst with two catalytic regions was prepared (see, for example, FIG. 2a).

[0132] The first catalytic region The first catalytic region is made of Cu supported on a CHA type zeolite with an SAR range of about 16 and a binder, with a total washcoat loading of about 1.5 g / in 3 and the Cu loading was about 3.3 wt % (based on the weight of CHA).

[0133] The first catalyst region was washcoated from the inlet end face of the ceramic substrate using standard coating procedures with a coating depth targeted to be 50% of the substrate length (400 cpsi, 4.3 mil wall thickness).

[0134] The second catalytic region As described in Catalyst Article 2.

[0135] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0136] Catalyst article 6 A catalyst with two catalytic regions was prepared (see, for example, FIG. 2a).

[0137] The first catalytic region The first catalytic region is comprised of Cu supported on an AEI type zeolite with an SAR range of about 20 and a binder, with a total washcoat loading of about 1.2 g / in 3 and the Cu loading was about 3.8 wt % (based on the weight of AEI).

[0138] The first catalyst region was washcoated from the inlet end face of the ceramic substrate using standard coating procedures with a coating depth targeted to be 50% of the substrate length (400 cpsi, 4.3 mil wall thickness).

[0139] The second catalytic region As described in Catalyst Article 2.

[0140] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0141] Catalyst article 7 A catalyst with two catalytic regions was prepared (see, for example, FIG. 2a).

[0142] The first catalytic region The first catalytic region is comprised of Cu supported on an AEI type zeolite with an SAR range of about 20 and a binder, with a total washcoat loading of about 1.5 g / in 3 and the Cu loading was about 3.8 wt % (based on the weight of AEI).

[0143] The first catalyst region was washcoated from the inlet end face of the ceramic substrate using standard coating procedures with a coating depth targeted to be 50% of the substrate length (400 cpsi, 4.3 mil wall thickness).

[0144] The second catalytic region As described in Catalyst Article 2.

[0145] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0146] Catalyst article 8 A catalyst with two catalytic regions was prepared (see, for example, FIG. 2a).

[0147] The first catalytic region The first catalytic region is comprised of Cu supported on an AEI type zeolite with an SAR range of about 20 and a binder, with a total washcoat loading of about 2.2 g / in 3 and the Cu loading was about 3.8 wt % (based on the weight of AEI).

[0148] The first catalyst region was washcoated from the inlet end face of the ceramic substrate using standard coating procedures with a coating depth targeted to be 50% of the substrate length (400 cpsi, 4.3 mil wall thickness).

[0149] The second catalytic region As described in Catalyst Article 2.

[0150] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0151] Catalyst article 9 A catalyst with two catalytic regions was prepared (see, for example, FIG. 2a).

[0152] The first catalytic region The first catalytic region is comprised of Cu supported on an AEI type zeolite with an SAR range of about 20 and a binder, with a total washcoat loading of about 2.8 g / in 3 and the Cu loading was about 3.8 wt % (based on the weight of AEI).

[0153] The first catalyst region was washcoated from the inlet end face of the ceramic substrate using standard coating procedures with a coating depth targeted to be 50% of the substrate length (400 cpsi, 4.3 mil wall thickness).

[0154] The second catalytic region As described in Catalyst Article 2.

[0155] The catalyst articles were dried at 100° C. and calcined at 500° C. for 45 minutes.

[0156] Catalytic performance tests were carried out using synthetic exhaust gas and catalyst samples were aged at 800° C. for 10 hours in 10% water, 5% O2, balance N2.

[0157] NH3 absorption test: The catalyst sample was heated to 150°C and fed with a gas mixture of 400 ppm NH3, 10% water, and the balance N2. The space velocity was 110 khz. -1 The total amount of NH3 stored was recorded when the catalyst was saturated with NH3.

[0158] NH3 Oxidation Test: Catalyst samples saturated with NH3 were heated from 100°C to 500°C at 50°C / min using a gas mixture of 300 ppm NH3, 0.5% O2, 300 ppm NO, balance N2. The temperature at which NH3 conversion reached 50% was recorded.

[0159] Table 9: Catalyst performance results from TWC-2, catalyst articles 1-9 Catalyst Articles 1-4 have comparable ammonia storage capacities and are significantly higher than TWC-2 technology. Catalyst Articles 6-9 show that ammonia storage increases with increasing Cu zeolite loading. The NH3 oxidation light-off for Catalyst Articles 1-9 is significantly lower than TWC-2. These results indicate that conventional TWC technology does not control NH3 emissions as effectively as Catalyst Articles 1-9.

[0160] [Table 9]

[0161] Example 4 - Improved catalytic performance The catalytic performance of the following system was tested with TWC-1 placed upstream and TWC-2 placed downstream. Comparison system 1: TWC-1 only Comparison system 2: TWC-1 + TWC-2 System 3: TWC-1 + TWC-2 + catalytic article 2

[0162] Catalyst performance tests were conducted in a gasoline vehicle under a driving cycle representative of Real Driving Emission (RDE). RDE testing was considered a reliable method of emission evaluation for engine operation. The final RDE emission value was the total emission divided by the distance traveled. The vehicle used was a Euro 6d fully qualified vehicle with a 1.5L direct injection turbocharged engine. The catalyst system was aged to represent the end of its useful life using a 60-hour fuel cut aging cycle with a target inlet temperature of 950°C for TWC-1. The temperature of the catalyst downstream of TWC-1 during this aging was 830°C.

[0163] The gasoline vehicle emission results under the RDE cycle for Comparative System 1 and Comparative System 2 are shown in Table 10. The results showed that the NH3 emissions of both Comparative Catalyst Systems 1 and 2 do not meet the expected European light-duty NH3 requirement of 10 mg / km. Thus, Comparative Systems 1 and 2, which use a typical catalyst in gasoline applications, do not perform to the NH3 emission requirements. The addition of catalyst article 2 of the present invention to System 3 (shown in Table 10) is effective in controlling NH3 emissions below the expected European requirement for light-duty vehicles.

[0164] [Table 10]

Claims

1. 1. A catalytic article for treating exhaust gases from a gasoline engine, comprising: a substrate having an axial length L and including an inlet end and an outlet end; a first catalyst region beginning at the inlet end, the first catalyst region comprising a first zeolite; a second catalyst region beginning at the outlet end, the second catalyst region comprising a second platinum group metal (PGM) component, a second oxygen storage capacity (OSC) material, and a second inorganic oxide; A catalytic article wherein the second PGM component is selected from the group consisting of palladium, platinum, rhodium, and combinations thereof.

2. The catalyst article of claim 1 , wherein the first catalyst region extends over 30 to 90% of the axial length L.

3. 3. The catalytic article of claim 1, wherein the second catalytic region extends over 30 to 90% of the axial length L.

4. The catalytic article of claim 1 or 2, wherein the second catalytic region overlaps the first catalytic region.

5. The catalytic article of claim 1 or 2, wherein the second catalytic region does not overlap the first catalytic region.

6. 3. The catalytic article of claim 1 or 2, wherein the first catalytic region further comprises a first transition metal selected from the group consisting of Fe, Cu, Mn, Co, Ni, Zn, and combinations thereof.

7. The catalytic article of claim 6, wherein the first transition metal is Cu and / or Fe.

8. 8. The catalyst article of claim 7, wherein Fe is 0.01 to 20 wt. % based on the weight of the first zeolite.

9. 8. The catalyst article of claim 7, wherein Cu is 0.01 to 20 wt. % based on the weight of the first zeolite.

10. 3. The catalyst article of claim 1 or 2, wherein the first zeolite has a framework type selected from the group consisting of ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, AST, ASV, ATT, BCT, BEA, BEC, BOF, BOG, BRE, CAN, CDO, CFI, CGS, CHA, CHI, CON, DAC, DDR, DFT, EAB, EDI, EPI, ERI, FER, GIS, GOD, IHW, ITE, ITW, LEV, KFI, MER, MFI, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, and ZON.

11. 11. The catalytic article of claim 10, wherein the first zeolite has a framework type selected from AEI, BEA, CHA, FER, FAU, MFA, or LEV.

12. 3. The catalytic article of claim 1 or 2, wherein the substrate is a flow-through monolith or a wall-flow filter.

13. 3. An emissions treatment system for treating an exhaust gas stream of a gasoline engine comprising the catalytic article of claim 1 or 2.

14. The emissions treatment system of claim 13 further comprising a TWC article upstream of the catalyst article.

15. A method for treating exhaust gas from a gasoline engine, comprising contacting said exhaust gas with the catalytic article of claim 1 or 2.

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