Selective ammonia oxidation catalyst

Abstract

The present invention relates to a selective ammonia oxidation (AMOx) catalyst comprising a platinum group metal and a support comprising TiO2 doped with 0-10 wt% of SiO2, WO3, ZrO2, Y2O3, La2O3, or a mixture thereof. The present invention also relates to a method for manufacturing a selective ammonia oxidation catalyst and an integrated catalyst system comprising a selective ammonia oxidation catalyst for treating an exhaust gas stream.

Description

Technology Field

[0001] The present invention relates to selective ammonia oxidation (AMO). x The invention relates to a catalyst, a method for manufacturing the same, and an integrated catalyst system for treating an exhaust gas stream.

[0002] Cross-reference of related applications

[0003] This application claims the benefit of priority to international application number PCT / CN2019 / 082306 filed on April 11, 2019, in its entirety. Background Technology

[0004] Diesel engine exhaust consists of soot, carbon monoxide, unburned or partially burned hydrocarbons, and nitrogen oxides (collectively NO x It is a heterogeneous mixture containing particulate emissions, such as gas emissions including (referred to as). A catalytic composition, often placed on one or more monolithic substrates, is located in an engine exhaust system and converts some or all of these exhaust components into innocuous compounds.

[0005] Selective Catalytic Reduction (SCR) is a strict NOx reduction method used in diesel and lean combustion engines. x NO used to meet emission targets x It is a reduction technology. In the ammonia SCR process, NO x (Generally composed of NO + NO2) reacts with ammonia (or an ammonia precursor such as urea) to form nitrogen (N2) on a catalyst typically composed of a base metal. This technology produces more than 90% of NO over a typical diesel driving cycle. x Since you can obtain conversion rates, aggressive NO x It is one of the best approaches to achieve reduction targets.

[0006] A characteristic of some SCR catalyst materials is the tendency to retain significant amounts of ammonia in the Lewis and Brønsted acidic regions of the catalyst surface during the low-temperature portion of a typical driving cycle. As exhaust gas temperatures subsequently rise, the ammonia can detach from the ammonia SCR catalyst surface and exit the vehicle's exhaust pipe. x Overdosing ammonia to increase the conversion rate is another potential scenario in which ammonia can be released from the ammonia SCR catalyst.

[0007] Ammonia slip in SCR catalysts presents many problems. The odor threshold of NH3 is 20 ppm in air. Eye and throat irritation is detectable at concentrations exceeding 100 ppm, skin irritation occurs at concentrations exceeding 400 ppm, and the immediate risk to life and health (IDLH) is 500 ppm. NH3 is corrosive, particularly in its aqueous form. Condensation of NH3 and water in the cooler region of the exhaust line downstream of the exhaust catalyst will produce a corrosive mixture.

[0008] Therefore, it is desirable to remove ammonia before it passes through the tailpipe. Selective Ammonia Oxidation (AMO) x The catalyst is used for this purpose to convert excess ammonia into N2. AMO x The catalyst must also produce minimal N2O, which is a potential greenhouse gas. Ideally, AMO x The catalyst must exhibit both high NH3 oxidation activity and high selectivity for N2. However, most known AMOs x Catalysts exhibit a trade-off relationship between activity and selectivity; that is, higher NH3 oxidation activity entails lower N2 selectivity (N2O and NO x Formation of higher levels of byproducts such as).

[0009] Generally, AMO x The catalyst comprises a noble metal supported on a refractory metal oxide support, such as alumina, silica, zirconia, or a combination thereof. Many refractory metal oxide supports are AMO, as described in patent documents WO2010 / 062730A1, WO2011 / 140251A1, WO 2017 / 037006A1, and US 2011 / 0286900A1. x Although disclosed as being used as a catalyst, pure titania is AMO x There are no reports in the art that it is used as a support for catalysts, which may be because pure titania is considered to have poor hydrothermal stability. It is well known that the specific surface area of ​​titania decreases significantly after aging at high temperatures, particularly above 560°C. Therefore, pure titania is generally not considered a suitable carrier for supported catalysts that must withstand severe hydrothermal aging conditions.

[0010] However, the inventors have developed an AMO containing Pt supported on a support made of a platinum group metal (PGM), in particular TiO2. X It was confirmed that the catalyst exhibited both high NH3 oxidation activity and high N2 formation selectivity, particularly resulting in less N2O formation.

[0011] The present invention relates to selective ammonia oxidation (AMO) comprising a support composed of platinum group metals (PGM) and TiO2. x ) provides a catalyst, wherein the TiO2 is doped with 0-10 wt% of SiO2, WO3, ZrO2, Y2O3, La2O3, or a mixture thereof.

[0012] The present invention also includes an integrated SCR / AMO for treating exhaust gas streams. x It provides a catalytic system, which

[0013] The above selective ammonia oxidation (AMO) x ) catalyst, and

[0014] Selective Catalytic Reduction (SCR) catalyst that promotes the reaction between ammonia and nitrogen oxides to selectively form nitrogen and H2O

[0015] Includes

[0016] The present invention also relates to a diesel oxidation catalyst (DOC), a catalytic soot filter (CSF), a reducing agent injector, and the integrated SCR / AMO. x An exhaust treatment system including a catalytic system is provided,

[0017] Optionally, the exhaust treatment system further comprises a second Selective Catalytic Reduction (SCR) catalyst and / or a Lean NOx Trap (LNT).

[0018] This AMO x The catalyst comprises a platinum group metal (PGM) and a pure TiO2 or routine refractory metal oxide support other than TiO2 doped with a small amount (<10%) of SiO2, WO3, ZrO2, Y2O3, La2O3, or a mixture thereof. X Lower NH3 light-off temperature T compared to the catalyst 70 It exhibits both high NH3 activity and high N2 selectivity, such as the formation of less nitrous oxide (N2O) byproducts. Brief explanation of the drawing

[0019] FIG. 1a illustrates the layout of an AMOx catalyst according to one or more embodiments. FIG. 1b illustrates the layout of an integrated catalyst system according to one or more embodiments. Fig. 1c illustrates the layout of an integrated catalyst system according to one or more embodiments. FIG. 2a illustrates the layout of an integrated catalyst system according to one or more embodiments. FIG. 2b illustrates the layout of an integrated catalyst system according to one or more embodiments. FIG. 3a illustrates the layout of an integrated catalyst system according to one or more embodiments. FIG. 3b illustrates the layout of an integrated catalyst system according to one or more embodiments. FIG. 4a illustrates the layout of an integrated catalyst system according to one or more embodiments. FIG. 4b illustrates the layout of an integrated catalyst system according to one or more embodiments. FIG. 4c illustrates the layout of an integrated catalyst system according to one or more embodiments. Figure 5 shows the catalytic performance (NH3 conversion and N2O formation) of the sample of Example 1 and the sample of Comparative Example after hydrothermal aging. Figure 6 shows the fresh and aged catalyst performance (NH3 conversion and N2O formation) of samples of Example 1, Example 2 and Comparative Example. Figure 7 shows the pore volume and pore diameter of TiO2. Figure 8 illustrates the catalytic performance (NH3 conversion and N2O formation) of the sample from the example and the sample from the comparative example after hydrothermal aging. Specific details for implementing the invention

[0020] Mode of implementation

[0021] As used in this specification and the appended claims, singular expressions include plural objects unless the context clearly indicates otherwise.

[0022] The term "NH3 oxidation" refers to the process in which ammonia (NH3) reacts with oxygen (O2) to produce N2, NO, NO2, N2O, preferably N2.

[0023] AMOx catalyst

[0024] In one or more embodiments, the selective ammonia oxidation (AMOx) catalyst comprises a platinum group metal (PGM) and a support made of TiO2. In the invention, the support is essentially composed of TiO2, wherein the TiO2 is doped with 0-10 wt% of SiO2, WO3, ZrO2, Y2O3, La2O3, or a mixture thereof, and 10 wt% is excluded.

[0025] As used herein, the terms “platinum group metal” or “PGM” refer to one or more chemical elements defined in the periodic table of elements, including platinum (Pt), palladium (Pd), rhodium (Rh), osmium (Os), iridium (Ir), and ruthenium (Ru), and mixtures thereof.

[0026] In certain embodiments, the platinum group metal includes a physical mixture of platinum group metals, or a combination that is chemically or atomically doped.

[0027] In certain embodiments, the AMOx catalyst disclosed herein is about 0.3 g / ft² when calculated as the total weight of PGM elements relative to the volume of the monolith substrate. 3 Up to about 20 g / ft 3 (about 0.01-0.70 g / L), preferably about 0.5 g / ft 3 Up to about 10 g / ft 3 (about 0.02-0.35 g / L), more preferably about 0.8 g / ft 3 Up to about 3 g / ft 3 It includes a total PGM loading of (approx. 0.03-0.10 g / L).

[0028] In certain embodiments, the platinum group metal comprises platinum (Pt). The ammonia oxidation catalyst is about 0.3 g / ft³ when calculated as the total weight of the platinum (Pt) component relative to the volume of the monolith substrate. 3 Up to about 20 g / ft 3 (about 0.01-0.70 g / L), preferably about 0.5 g / ft 3 Up to about 10 g / ft 3(about 0.02-0.35 g / L), more preferably about 0.8 g / ft 3 Up to about 3 g / ft 3 It contains a platinum (Pt) component in an amount ranging from about 0.03 to 0.10 g / L. In a more specific embodiment, the platinum group metal is Pt, and no other platinum group metal is present.

[0029] As used herein, the term “no other platinum group metals” means that platinum group metals other than platinum have not been intentionally added to the catalyst, and that other platinum group metals are present in the catalyst in an amount of less than about 1 weight percent, including less than about 0.75 weight percent, less than about 0.5 weight percent, less than about 0.25 weight percent, and less than about 0.1 weight percent. That is, the catalyst does not contain palladium (Pd), ruthenium (Ru), osmium (Os), or iridium (Ir). In one or more embodiments, the catalyst contains platinum and does not contain other platinum group metals. In these embodiments, the catalyst does not contain palladium (Pd), ruthenium (Ru), osmium (Os), iridium (Ir), or rhodium (Rh).

[0030] In certain embodiments, the platinum group metal includes palladium (Pd). The AMOx catalyst is about 0.3 g / ft³ when calculated as the total weight of the palladium (Pd) component relative to the volume of the substrate. 3 Up to about 20 g / ft 3 , preferably about 0.5 g / ft 3 Up to about 10 g / ft 3 , more preferably about 0.8 g / ft 3 Up to about 3 g / ft 3 It contains palladium (Pd) in a range of amounts.

[0031] In certain embodiments, the platinum group metal includes rhodium (Rh). The AMOx catalyst is about 0.3 g / ft³ when calculated as the total weight of the rhodium (Rh) component relative to the volume of the substrate. 3 Up to about 20 g / ft 3, preferably about 0.5 g / ft 3 Up to about 10 g / ft 3 , more preferably about 0.8 g / ft 3 Up to about 3 g / ft 3 It contains rhodium (Rh) components in a range of amounts.

[0032] In one or more specific embodiments, TiO2 is 5-120 m after 10 vol% H2O hydrothermal aging at 750°C for 20 hours. 2 / g, especially 7-50 m 2 / g, even more especially 9-25 m 2 It has a BET specific surface area of ​​ / g. Before aging, fresh TiO2 is 40-400 m² 2 / g, especially 50-200 m 2 / g, even more especially 75-100 m 2 It has a BET specific surface area of ​​ / g.

[0033] As used herein, the term "BET surface area" has the conventional meaning of the Brunauer, Emmett, Teller method for determining surface area by N2 adsorption.

[0034] In one or more specific embodiments, the TiO2 is 0.01 to 0.2 cm after aging at 750°C for 20 hours. 3 It has an average pore volume (BET) in the range of / g; or an average pore diameter (BET) in the range of 5 to 50 nm after aging at 750°C for 20 hours. Before aging, fresh TiO2 is 5 to 30 cm² 3 It has an average pore volume (BET) in the range of / g, or an average pore diameter (BET) in the range of 2.5 to 20 nm.

[0035] In one or more embodiments, TiO2 has an average particle size in the range of 250-450 nm, preferably 300-400 nm, after aging at 750°C for 20 hours. Before aging, fresh TiO2 has an average particle size in the range of 20-120 nm, preferably 45-95 nm.

[0036] In one or more embodiments, the AMOx catalyst is, after aging in 10 volume% H2O hydrothermal aging at 750°C for 20 hours, about 5 to about 120 m 2 / g, preferably 7-50 m 2 / g, more preferably 9-25 m 2 It has a surface area (BET) in the range of / g. Before aging, fresh AMOx catalyst is 40-400 m² 2 / g, especially 50-200 m 2 / g, even more especially 75-100 m 2 It has a BET specific surface area of ​​ / g.

[0037] In one or more specific embodiments, the AMOx catalyst is 0.01 to 0.2 cm after aging at 750°C for 20 hours. 3 It has an average pore volume (BET) in the range of / g; or an average pore diameter (BET) in the range of 5 to 50 nm after aging at 750°C for 20 hours. Before aging, the fresh AMOx catalyst has a diameter of 5 to 30 cm 3 It has an average pore volume (BET) in the range of / g or an average pore diameter (BET) in the range of 2.5 to 20 nm.

[0038] In one or more embodiments, the AMOx catalyst has an average particle size in the range of 250-450 nm, preferably 300-400 nm, after aging at 750°C for 20 hours. Before aging, the fresh AMOx catalyst has an average particle size in the range of 20-120 nm, preferably 45-95 nm.

[0039] In one or more embodiments, the AMOx catalyst is about 0.1 to about 1.5 g / in with respect to the volume of the substrate. 3 (about 6 to 90 g / L), preferably 0.2 to about 1.0 g / in 3 It is coated on a substrate with a dry gain of (about 12 to 60 g / L).

[0040] One or more embodiments comprising an AMOx catalyst and a second catalytic composition may be referred to as a "multi-component" AMOx catalyst.

[0041] In one or more embodiments, the AMOx catalyst may optionally be integrated on a substrate as a catalyst or through different layouts (zoning, layering, homogeneous blending, etc.) with other functions such as selective catalytic reduction (SCR) catalyst, CO oxidation, hydrocarbon storage, hydrocarbon oxidation, NOx storage, NO oxidation, etc.

[0042] In one or more specific embodiments, the catalytic system for treating the exhaust gas stream is AMO x A catalyst and a selective catalytic reduction (SCR) catalyst are included to promote the reaction of ammonia and nitrogen oxides to selectively form nitrogen and H2O, wherein the selective catalytic reduction (SCR) catalyst is located in an upstream region of the AMOx catalyst; is located in a layer above the AMOx catalyst; is homogeneously blended with the AMOx catalyst; or is any combination thereof.

[0043] write

[0044] A useful material is a three-dimensional object having length, diameter, and volume similar to a cylinder. The shape does not necessarily have to correspond to a cylinder. The length is an axial length defined by an inlet end and an outlet end.

[0045] According to one or more embodiments, the substrate for the disclosed composition(s) may be composed of any material typically used to manufacture automotive catalysts and will typically include a metal or ceramic honeycomb structure. The substrate typically serves as a substrate for the catalyst composition by providing a plurality of wall surfaces to which the washcoat composition is applied and adhered.

[0046] Any suitable substrate for the catalytic article disclosed herein, for example, a monolithic substrate of the type having fine, parallel gas flow passages extending from an inlet or outlet surface of the substrate so as to be open for fluid flow through, ("flow-through substrate") may be used.

[0047] In certain embodiments, the substrate is a flow-through substrate (e.g., a monolithic substrate comprising a flow-through honeycomb monolithic substrate). The flow-through substrate has fine, parallel gas flow passages extending from an inlet end to an outlet end of the substrate such that the passages are open to fluid flow. The passages, which are essentially straight paths from the fluid inlet to the fluid outlet, are defined by walls on which a catalytic coating is disposed so that the gas flowing through the passages comes into contact with a catalytic material. The flow passages of the flow-through substrate are thin-walled channels that may have a suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, etc. The flow-through substrate may be ceramic or metal.

[0048] Another suitable substrate is of the type having a plurality of fine and substantially parallel gas flow passages extending along the longitudinal axis of the substrate, wherein typically each passage is blocked at one end of the substrate body and an alternative passage is blocked at the opposite end-face ("wall-flow filter").

[0049] In certain embodiments, the catalyst substrate comprises a honeycomb substrate in the form of a wall-flow filter or a flow-through substrate, preferably a flow-through honeycomb substrate.

[0050] SCR catalyst

[0051] In one or more embodiments, the SCR catalyst comprises a zeolite or non-zeolite molecular sieve and a promoter metal.

[0052] As used herein, the term “molecular sieve” refers to a skeletal material, such as a zeolite and other skeletal materials (e.g., isomorphically substituted materials), which may be used as a catalyst in the form of microparticles in combination with one or more promoter metals. A molecular sieve is a material based on an extensive network of oxygen ions having a substantially uniform pore distribution with an average pore size of 20 Å or less, generally containing tetrahedral type sites. The pore size is defined by the ring size. As used herein, the term “zeolite” refers to specific examples of molecular sieves comprising silicon and aluminum atoms. According to one or more embodiments, by defining a molecular sieve by its skeletal type, it will be understood that any isomorphic skeletal material, such as SAPO, ALPO, and MeAPO materials having the same skeletal type, is intended to be included as a zeolite material.

[0053] In one or more specific embodiments, the molecular sieve material has a skeletal type selected from AEI, AFT, AFX, CHA, DDR, EAB, EMT, ERI, FAU, FER, GME, JSR, KFI, LEV, LTA, LTL, LTN, MFI, MOZ, MSO, MWW, OFF, PAU, RHO, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC, UEI, WEN, and combinations thereof. In one preferred embodiment of the invention, the molecular sieve material has a skeletal type selected from the group consisting of CHA, AEI, AFX, ERI, KFI, LEV, AFT, EAB, DDR, PAU, RHO, SAV, SAT, TSC, UEI, LTA, MFI, FER, FAU, and combinations thereof. In another specific embodiment, the molecular sieve material has a skeletal type selected from CHA, AEI, and AFX. In one or more very specific embodiments, the molecular sieve material has a CHA skeletal type.

[0054] The silica to alumina ratio of the molecular sieve material can vary widely. In one or more specific embodiments, the molecular sieve material has a silica to alumina molar ratio (SAR) in the range of 2 to 200, including 5 to 100, 8 to 50, and 10 to 30.

[0055] In one or more embodiments, the molecular sieve material has a crystallite size of 0.01 microns to 10 microns, or preferably a crystallite size of 0.1 microns to 5.0 microns.

[0056] When calculated as oxides, the promoter metal content of the catalyst is at least about 0.1 wt% when reported on a volatile-free basis in one or more embodiments. In certain embodiments, the promoter metal content is in the range of 0.1 wt% to about 10 wt% when calculated as oxides, including 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, 0.25, and 0.1 wt%, based on the total weight of the calcined molecular sieve reported on a volatile-free basis in each case.

[0057] In certain embodiments, the promoter metal comprises Cu, and the Cu content is in the range of 0.1 wt% to about 10 wt% or less, including 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, 0.25, and 0.1 wt% when calculated as CuO, based on the total weight of the calcined molecular sieve reported on a non-volatile basis in each case. In certain embodiments, the Cu content of the molecular sieve is in the range of about 1 to about 10 wt% when calculated as CuO.

[0058] In other specific embodiments, the promoter metal comprises Fe, and the Fe content is in the range of 0.1 wt% to about 10 wt% or less, including 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, 0.25, and 0.1 wt% when calculated as Fe2O3, based on the total weight of the calcined molecular sieve reported on a non-volatile basis in each case. In specific embodiments, the Fe content of the molecular sieve is in the range of about 1 to about 10 wt% when calculated as Fe2O3. In specific embodiments, the Fe content of the molecular sieve is in the range of about 1 to about 10 wt% when calculated as Fe2O3.

[0059] In other specific embodiments, the promoter metal is Cu, Fe, or a combination thereof.

[0060] Layout of the AMOx catalyst

[0061] In one or more embodiments, referring to FIG. 1a, the AMOx catalyst (1) is wash-coated onto a substrate (0) to form a layer.

[0062] In another embodiment, the AMOx catalyst (1) further comprises an SCR catalyst by homogeneous blending to form an integrated catalyst system, wherein the weight ratio of the SCR catalyst to the AMOx catalyst is 0.5-15, preferably 2-10, more preferably 3.5-7.5.

[0063] In a specific embodiment, the AMOx catalyst (1) may extend from the outlet end (6) toward the inlet end (5) in a range of about 5% to about 100%, including 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of the substrate length. In another specific embodiment, the AMOx catalyst may extend from the inlet end (5) toward the outlet end (6) in a range of about 5% to about 100%, including 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of the substrate length.

[0064] In another embodiment, the AMOx catalyst is integrated with the SCR catalyst. Referring to FIG. 1b, the integrated catalyst system comprises a substrate (0) that is wash-coated with the AMOx catalyst (1) to form a first layer (or bottom wash-coat layer), and the SCR catalyst (2) is wash-coated on top of the first layer to form a second layer (or top wash-coat layer); the weight ratio of the SCR catalyst to the AMOx catalyst is 0.5-15, preferably 2-10, more preferably 3.5-7.5.

[0065] As used herein, the terms “upstream” and “downstream” refer to relative directions according to the flow of an engine exhaust gas stream from the engine toward the tailpipe, wherein the engine is located upstream and the tailpipe, and any pollution reduction articles such as filters and catalysts, are located downstream from the engine.

[0066] In another embodiment, the AMOx catalyst is integrated with the SCR catalyst. Referring to FIG. 1c, the integrated catalyst system comprises a substrate (0) that is wash-coated with the AMOx catalyst (1) to form a first layer (or lower wash-coat layer), and the first SCR catalyst (2) is coated upstream of the second SCR catalyst (3). The catalyst (2) and the catalyst (3) are coated on the AMOx catalyst (1).

[0067] In a specific other embodiment, the promoter metal of the first SCR catalyst (2) and the second SCR catalyst (3) is independently selected from Cu, Fe, or a combination thereof.

[0068] It will be understood that the lengths of the first SCR catalyst (2) and the second SCR catalyst (3) may vary. In one or more embodiments, the first SCR catalyst (2) and the second SCR catalyst (3) may have the same length. In another embodiment, the first SCR catalyst (2) may be in the range of about 5% to 95%, including about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, or about 90% of the length (L) of the substrate (0), and the second SCR catalyst (3) each cover the remaining portion of the length L of the substrate (0) without a gap (4). In another embodiment, the first SCR catalyst (2) may be about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90% of the length (L) of the substrate (0), and the second SCR catalyst (3) covers the remaining portion of the length (L) of the substrate (0) together with the gap (4) as shown in FIG. 1c.

[0069] In another embodiment, the AMOx catalyst is integrated with the SCR catalyst. Referring to FIG. 2a, the integrated catalyst system comprises a substrate (0) that is washed coated with the AMOx catalyst (1) to form a first layer (or lower wash coat layer), and the SCR catalyst (2) is washed coated over the first layer to form a second layer (or top wash coat layer).

[0070] In a specific embodiment, the AMOx catalyst (1) may extend from the outlet end (6) toward the inlet end (5) in a range of about 5% to about 100%, including 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of the substrate length.

[0071] In another embodiment, the AMOx catalyst is integrated with the SCR catalyst. Referring to FIG. 2b, the integrated catalyst system comprises a substrate (0) that is washed coated with the AMOx catalyst (1) to form a first layer (or lower wash coat layer), and the SCR catalyst (2) is washed coated on top of the first layer to form a second layer (or top wash coat layer).

[0072] In a specific embodiment, the AMOx catalyst (1) may extend from the inlet end (5) toward the outlet end (6) in a range of about 5% to about 100%, including 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of the substrate length.

[0073] In another embodiment, the AMOx catalyst is integrated with the SCR catalyst. Referring to FIG. 3a, the integrated catalyst system comprises a substrate (0a) washed coated with the AMOx catalyst (1) and a substrate (0) washed coated with the SCR catalyst (2). The substrate (0) is located upstream of the substrate (0a). It will be understood that the substrate (0) and the substrate (0a) may be the same or different.

[0074] In another embodiment, the AMOx catalyst is integrated with the SCR catalyst. Referring to FIG. 3b, the integrated catalyst system comprises a substrate (0) washed coated with an SCR catalyst (2) located upstream of the AMOx catalyst (1).

[0075] It will be understood that the lengths of the SCR catalyst (2) and the AMOx catalyst (1) may vary. In one or more embodiments, the SCR catalyst (2) and the AMOx catalyst (1) may have the same length. In another embodiment, the SCR catalyst (2) may be in the range of about 5% to 95%, including about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, or about 90% of the length (L) of the substrate (0), and the AMOx catalyst (1) covers the remainder of the length L of the substrate (0) without a gap (4). In another embodiment, the SCR catalyst (2) may be about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90% of the length (L) of the substrate (0), and the AMOx catalyst (1) covers the remaining portion of the length (L) of the substrate (0) with a gap (4) as shown in FIG. 3b.

[0076] In addition, those skilled in the art will understand that the upstream zone and the downstream zone may overlap at least partially. As used herein, the term “at least partially overlapping” means that the upstream zone and the downstream zone may overlap by an amount ranging from about 0.1% to about 99%.

[0077] In one or more embodiments, the upstream and downstream zones may completely overlap (e.g., about 100%). Referring to FIG. 4a, an exemplary embodiment of an integrated system is illustrated. The integrated catalyst system includes an SCR catalyst (2) located upstream of an AMOx catalyst (1) on a substrate (0).

[0078] In a specific embodiment, the SCR catalyst (2) extends to a range of about 100% of the substrate length. The AMOx catalyst (1) may extend from the inlet end toward the outlet end in a range of about 5% to about 100%, including 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of the substrate length.

[0079] In another specific embodiment, the SCR catalyst (2) extends to a range of about 100% of the substrate length. Referring to FIG. 4b, the AMOx catalyst (1) may extend from the outlet end toward the inlet end in a range of about 5% to about 100%, including 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of the substrate length.

[0080] In one or more embodiments, the upstream region containing the SCR catalyst partially overlaps with the downstream region containing the AMOx catalyst. Referring to FIG. 4c, an exemplary embodiment of the integrated system is illustrated. The upstream SCR catalyst (2) extends from the inlet end (5) of the substrate (0) through less than the total length (L) of the substrate (0) and partially overlaps with the downstream AMOx catalyst (1). The AMOx catalyst (1) extends from the outlet end (6) of the substrate (0) through less than the total length (L) of the substrate (0).

[0081] Examples

[0082] The present invention is now further illustrated with reference to the following examples, but the examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0083] Example 1

[0084] Preparation of AMOx slurry

[0085] The AMOx coating slurry was prepared via the incipient-wetness impregnation method. First, 250 g of TiO2 support (purity >98%, anatase phase) was placed in a container, and then 6 g of platinum ammine solution was added dropwise under constant stirring to ensure uniform distribution. Subsequently, the resulting impregnated powder was diluted with deionized H2O to prepare a slurry with a solid content of 42 wt%. The mixture was then milled to obtain a particle size of D90 = 6–9 μm.

[0086] Preparation of SCR Slurry

[0087] The SCR slurry was prepared from a mixture of Cu-CHA, zirconium acetate binder, and H2O. 21 g of zirconia acetate binder (solid content = 30.0 wt%) was added dropwise to 160 g of deionized water under stirring. After mixing well, 120 g of Cu-CHA powder was slowly added to the mixture under vigorous stirring (about 400 rpm), and the ratio of Cu-CHA to ZrO2 was about 19:1 based on the dry weight of each material. The solid content was less than 42%.

[0088] Manufacturing of integrated catalyst systems

[0089] A ceramic monolithic core (1"×3", 400 / 4) was used for a coating process by immersing it in an AMOx or SCR slurry. Referring to Fig. 1b, it was first coated with an AMOx slurry. After removing excess slurry using compressed air, the wet sample was briefly dried in flowing air at 250°C. Subsequently, the core was calcined in a muffle furnace at 450°C (ramp 4°C / min) for 1 hour, then cooled to 250°C and weighed to determine the AMOx catalyst loading. The drying gain of the AMOx layer was 0.5 g / in⁻¹.3 It is (30 g / L). After the AMOx layer is completed, the SCR layer is applied using the same process as for manufacturing the AMOx layer, but the SCR layer drying gain is 1.79 g / in 3 (110 g / L)

[0090] The optimization of the integrated catalyst design of Fig. 1b can be used for the design of the front or rear of the catalyst shown in Fig. 1c, Fig. 2a, b, Fig. 3a, b, Fig. 4a, b, or c.

[0091] Examples 2-3 and Comparative Examples 1-6

[0092] The catalysts of Examples 2-3 and Comparative Examples 1-6 are prepared as in Example 1, except that the support used in the AMOx slurry is different, as shown in Table 1.

[0093] Formulation of each integrated catalyst system Example number AMOx catalyst SCR catalyst Platinum amine solution Support 120 g Cu-CHA; 21 g zirconia acetate (solids: 30 wt%) CuO loading: 3.25 wt%; SiO2 / Al2O3 ratio of CHA: 27.2 Example 1 6 g 250 g TiO2 Example 2 6 g 250 g SiO2-TiO2 (5% SiO2, 95%TiO2,) Example 3 6 g 250 g SiO2-TiO2 (8% SiO2, 92%TiO2,) Example 4 6 g 250 g SiO2-TiO2 (10% SiO2, 90% TiO2,) Comparative Example 1 6 g 250 g SiO2-Al2O3 (98.5%Al2O3, 1.5%SiO2) Comparative Example 2 6 g 250 g HY Comparative Example 3 6 g 250 g H-CHA Comparative Example 4 6 g 250 g H-ZSM-5 Comparative Example 5 6 g 250 g CeO2

[0094] The generated integrated catalyst system has the composition as shown in Table 2.

[0095] Composition of each integrated catalyst system Example number AMOx catalyst SCR catalyst PGM Support Example 1 2 g / ft 3 Pt 0.5 g / in 3 TiO2 1.79 g / in 3 With-CHA Example 2 2 g / ft 3 Pt 0.5 g / in 3 SiO2-TiO2(5%SiO2, 95%TiO2) 1.79 g / in 3 With-CHA Example 3 2 g / ft 3 Pt 0.5 g / in 3 SiO2-TiO2(8%SiO2, 92%TiO2) 1.79 g / in 3 With-CHA Example 4 2 g / ft 3 Pt 0.5 g / in 3 SiO2-TiO2(10%SiO2, 90%TiO2) 1.79 g / in 3 With-CHA Comparative Example 1 2 g / ft 3 Pt 0.5 g / in 3 Al2O3-SiO2(98.5%Al2O3, 1.5%SiO2) 1.79 g / in 3 With-CHA Comparative Example 2 2 g / ft 3 Pt 0.5 g / in 3 Y zeolite 1.79 g / in 3 With-CHA Comparative Example 3 2 g / ft 3 Pt 0.5 g / in 3 CHA zeolite 1.79 g / in 3 With-CHA Comparative Example 4 2 g / ft 3 Pt 0.5 g / in 3 ZSM-5 zeolite 1.79 g / in 3 With-CHA Comparative Example 5 2 g / ft 3 Pt 0.5 g / in 3 CeO2 1.79 g / in 3 With-CHA

[0096] NH 3 Test method for oxidation :

[0097] All catalyst tests were performed in a flow reactor using simulated diesel exhaust with a 1" × 3" monolith core. 1000 ppm NH3 at 150,000 h -1 It was added along with other components of the exhaust gas containing 10% O2, 8% CO2, and 7% H2O at a space velocity, with the remainder being N2. This NH3 oxidation experiment was performed in the range of 175–400°C at a temperature ramp rate of 20°C / min. The NH3 conversion rate was ([NH3] in - [NH3] out ) / [NH3] in It was calculated as × 100%; T 70 Silver is defined as the temperature at which the catalyst converts 70% of NH3; lower T70 It means a more active catalyst for NH3 oxidation.

[0098] Figure 5 shows the catalytic performance (NH3 conversion and N2O formation) of the sample of Example 1 and the sample of the Comparative Example after hydrothermal aging at 750°C for 20 hours. The sample of the present invention using Pt / TiO2 (Example 1) is T compared to the sample of the Comparative Example 70 This shows that the sample of the present invention has superior activity compared to the comparison sample, but with less N2O formation. Without being bound by a specific theory, the improved activity may be due to the synergistic effect of Pt and TiO2.

[0099] Figure 6 shows the fresh (left) and aged (right, 750℃ / 20h) catalyst performance (NH3 conversion and N2O formation) of the sample of Example 1 and the sample of Comparative Example.

[0100] This shows that the sample of the present invention using Pt / TiO2 (Example 1) has improved catalytic performance after aging compared to a fresh catalyst, that is, the sample of the present invention has a lower T after aging than a fresh catalyst. 70 and simultaneously exhibits less N2O formation. Again, without being bound by a specific theory, the improvement by aging suggests that Pt, considered the active site for NH3 oxidation, O This may be due to the formation of more of [the substance]. In addition, changes in the properties of the support (TiO2) during aging can promote the desorption of reaction intermediates, thereby reducing N2O formation.

[0101] The TiO used in Example 1 2 Properties of

[0102] The BET surface area, pore volume, and pore diameter of TiO2 were tested using Micrometrics triStar II. TiO2 samples were slowly heated to 473 K and maintained at this temperature under vacuum (approx. 50 mTorr) for 24 hours. Then, the samples were transferred to an adsorption unit, and N2 adsorption was measured at the liquid N2 temperature. Figure 7 shows the pore volume and pore diameter of aged TiO2 and fresh TiO2.

[0103] BET surface area of ​​aged TiO2 and fresh TiO2 Sample BET surface area (m 2 / g) Average pore volume (cc / g) Average pore diameter (nm) Fresh TiO2 82.78 0.29 14.0 TiO2 aged at 750℃ / 20h 17.03 0.08 24.1

[0104] It will be apparent to those skilled in the art that various modifications and variations may be made to the present invention without departing from the scope or spirit of the invention. Accordingly, the present invention is intended to include such modifications and variations within the scope of the appended claims and their equivalents.

Claims

Claim 1 A selective ammonia oxidation (AMOx) catalyst comprising a support made of platinum and TiO2, wherein the TiO2 is doped with 0-10 wt% SiO2, and the TiO2 is 5-120 m after hydrothermal aging with 10 vol% H2O at 750°C for 20 hours. 2 Selective ammonia oxidation (AMOx) catalyst having a BET specific surface area of ​​ / g. Claim 2 In claim 1, the TiO2 is 7-50 m after 10 volume% H2O hydrothermal aging at 750°C for 20 hours. 2 Selective AMOx catalyst having a BET specific surface area of ​​ / g. Claim 3 In claim 1, the TiO2 is 0.01 to 0.2 cm when aged at 750°C for 20 hours. 3 Selective AMOx catalyst having an average pore volume in the range of / g; or an average pore diameter in the range of 2 to 50 nm upon aging at 750°C for 20 hours. Claim 4 In claim 1, the loading of the platinum group metal is 0.3 g / ft² when calculated as the total weight of the platinum group metal relative to the volume of the substrate. 3 Up to 20g / ft 3 , or 0.5g / ft 3 Up to 10 g / ft 3 , or 0.8g / ft 3 Up to 3g / ft 3 Selective AMOx catalyst in the range. Claim 5 delete Claim 6 In claim 1, the AMOx catalyst is 0.1 g / in when calculated as the total weight of the platinum group metal relative to the volume of the substrate. 3 Up to 1.5 g / in 3 Selective AMOx catalyst coated on a substrate with a range of dry gain. Claim 7 An integrated catalyst system comprising a selective AMOx catalyst according to claim 1 and a selective catalytic reduction (SCR) catalyst, wherein the SCR catalyst is located in an upstream region of the AMOx catalyst, is located in a layer above the AMOx catalyst, is homogeneously blended with the AMOx catalyst, or is any combination thereof. Claim 8 An integrated catalyst system according to claim 7, wherein the SCR catalyst comprises a promoter metal on a molecular sieve material. Claim 9 An integrated catalyst system according to claim 8, wherein the molecular sieve material is selected from framework type CHA, AEI, AFX, ERI, KFI, LEV, AFT, EAB, DDR, PAU, RHO, SAV, SAT, TSC, UEI, LTA, MFI, FER, FAU and combinations thereof. Claim 10 An integrated catalyst system according to claim 9, wherein the molecular sieve material is of the CHA backbone type, and the crystallite size of the CHA is 0.1 to 5 microns. Claim 11 In claim 8, the integrated catalyst system wherein the molecular sieve material has a silica to alumina ratio in the range of 2 to 200. Claim 12 An integrated catalyst system according to claim 8, wherein the promoter metal is Cu, Fe, or a combination thereof, and the promoter metal content of the SCR catalyst is in the range of 0.1 wt% to 10 wt% when calculated as oxide. Claim 13 In claim 8, the integrated catalyst system wherein the AMOx catalyst and the SCR catalyst are integrated as a single catalyst or integrated on a single substrate. Claim 14 In paragraph 13, an integrated catalytic system wherein the above description is a flow-through monolith or a wall-flow filter. Claim 15 An exhaust treatment system comprising a diesel oxidation catalyst (DOC), a catalyzed soot filter (CSF), a reductant injector, and an integrated catalytic system of any one of claims 6 to 14, wherein optionally, the exhaust treatment system further comprises a second selective catalytic reduction (SCR) catalyst and / or a lean NOx trap (LNT).

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