RU2783210C2 - Diesel fuel oxidation catalyst having capture area for sulfur-containing impurities - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to a system for release of exhaust gases for processing of exhaust gases produced by a diesel engine, as well as to a heavy-duty vehicle with a diesel engine, containing this system. The system for release of exhaust gases contains an oxidation catalyst and a downstream located device for control of emissions, which is a selective catalytic reduction catalyst or a catalyst of a selective catalytic reduction filter. At the same time, the oxidation catalyst does not contain rhodium and contains: a flow monolithic base; a catalytic zone located at an inlet end of the base, wherein the catalytic zone has a length from 10 to 90% of a length of the base, and containing catalytic material containing platinum group metal (PGM) selected from a group consisting of platinum (Pt), palladium (Pd), and a combination of platinum (Pt) and palladium (Pd); as well as a capture zone located at an outlet end of the base and having a length from 15 to 65% of the length of the base. The capture zone contains capturing material for capture of at least one sulfur-containing impurity in exhaust gases produced by the diesel engine, and this capturing material contains metal for reaction interaction with sulfur oxide in exhaust gases and refractory oxide particles. Moreover, metal for reaction interaction with sulfur oxide in exhaust gases is palladium (Pd), and refractory oxide particles have an average specific surface area of ≤ 50 m²/g, determined by means of physical nitrogen adsorption at -196°C, using a volume-metric method and using an isothermal adsorption equation according to BET. In the system, the catalytic zone is adjacent to the capture zone, or the capture zone both is adjacent to the catalytic zone and covers the catalytic zone.

EFFECT: limitation of maximum amount of sulfur permissible in diesel fuel.

12 cl, 12 dwg, 1 tbl, 2 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The present invention relates to an oxidation catalyst and an exhaust system for treating exhaust gases generated by a diesel engine. This invention further relates to a method or use of an oxidation catalyst for capturing at least one sulfur-containing impurity in exhaust gases generated by a diesel engine. This invention also relates to a vehicle containing an oxidation catalyst or an exhaust system.

BACKGROUND OF THE INVENTION

Diesel engines produce exhaust gases that contain many pollutants that are subject to worldwide environmental legislation. These pollutants include carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxides (NO _x ) and particulate matter (PM). In order to comply with the legally established allowable levels of pollutants that can be released into the atmosphere, exhaust systems for treating exhaust gases generated by a diesel engine usually contain several devices for controlling emissions. In such exhaust systems, exhaust gases typically pass to a first emission control device that is capable of oxidizing carbon monoxide (CO) and unburned hydrocarbons (HC) that are present in the gas.

In addition to the pollutants mentioned above, exhaust gases may contain impurities that come from certain fuels that have been used. Diesel fuel often contains sulfur-containing impurities. Under the lean conditions used for combustion in a diesel engine, sulfur-containing impurities usually form sulfur oxides. These sulfur oxides can poison some of the catalytically active metals in exhaust system emission control devices. In addition, sulfur oxides may form particulate matter or may contribute to the formation of acid rain when released into the atmosphere.

Many countries have legislation in place to limit the maximum amount of sulfur allowed in diesel fuel. In addition to the application's environmental benefits, such legislation also promotes the application of new exhaust control technologies that cannot tolerate the high levels of sulfur in diesel exhaust that used to be. Despite the reduction in sulfur content, the performance of some emission control devices may still be impaired by sulfur oxide poisoning.

SUMMARY OF THE INVENTION

The present invention provides an oxidation catalyst for treating exhaust gases generated by a diesel engine. The oxidation catalyst contains: base; a capturing material for capturing at least one sulfur-containing contaminant in exhaust gases generated by the diesel engine; where the exciting material contains a metal for reaction with sulfur oxide in the exhaust gases and particles of refractory oxide, preferably, where the particles of refractory oxide have an average specific surface area ≤50 m ² /g; and a catalytic region located on the basis; where the catalytic region contains a catalytic material containing a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd) and a combination of platinum (Pt) and palladium (Pd).

The present inventors have developed a cost-effective entrainment material for trapping or capturing at least one sulfur-containing contaminant in exhaust gases generated by a diesel engine. The entraining material reduces or prevents degradation of the oxidative activity of the oxidation catalyst, such as towards carbon monoxide (CO), unburned hydrocarbons (HC), and/or nitric oxide (NO). The entrainment material may also prevent any sulfur-containing impurities from degrading the performance of an emission control device that is downstream of a diesel oxidation catalyst (DOC) such as a selective catalytic reduction (SCR) catalyst or a selective catalytic reduction filter (SCRF ^TM ) catalyst. , by trapping impurities inside the diesel oxidation catalyst (DOC).

The present invention also relates to an exhaust system for treating exhaust gases generated by a diesel engine. The exhaust system contains the oxidation catalyst of the present invention and optionally (namely additionally) an emission control device.

According to the present invention, a vehicle is further provided. The vehicle comprises a diesel engine and an oxidation catalyst or exhaust system according to the present invention.

The invention also relates to the use of an entrainment material, or an entrainment region containing an entrainment material (for example, in or as part of an oxidation catalyst), to capture or trap at least one sulfur-containing contaminant in exhaust gases generated by a diesel engine. The entraining material contains a metal to react with sulfur oxide in exhaust gases and refractory oxide particles, preferably wherein the refractory oxide particles have an average specific surface area of ≦50 m ² /g. The oxidation catalyst contains an entrapment material or an entrapment region; basis; and a catalytic region located on the base, where the catalytic region contains a catalytic material containing a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd) and a combination of platinum (Pt) and palladium (Pd).

The present invention further relates to a method for trapping or trapping at least one sulfur-containing contaminant in exhaust gases generated by a diesel engine. This method includes the step of passing exhaust gases generated by a diesel engine through an exhaust system containing the oxidation catalyst of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1-8, 10 and 11 are schematic drawings of the oxidation catalysts of this invention.

Fig. 1 shows an oxidation catalyst having a capture bed (2) located on a catalytic bed (3). The catalytic layer (3) is located on the base (1).

Fig. 2 shows an oxidation catalyst having a captive bed (2) located on the catalytic region. The catalytic region has a first catalytic zone (3) and a second catalytic zone (4), which are located on the base (1).

Fig. 3 shows an oxidation catalyst having a capture zone (2) located on the base (1) at the inlet end of the oxidation catalyst. There is a catalytic zone (3) at the outlet end of the oxidation catalyst.

Fig. 4 shows an oxidation catalyst having a capture zone (2) located at the inlet end of the base (1). There is a first catalytic zone (3) located on the second catalytic zone (4), which are located at the outlet end of the base.

Fig. 5 shows an oxidation catalyst having a catalytic layer (3) disposed on a base (1). There is a capture zone (2) at the inlet end of the base, which is located on the catalytic layer (3).

Fig. 6 shows an oxidation catalyst having a capture zone (2) located on the base at the inlet end. The capture area (2) partially covers the catalytic zone (3). The catalytic zone (3) is located at the outlet end of the base.

Fig. 7 shows an oxidation catalyst having a capture zone (2) and a first catalytic zone (3) which are located on the second catalytic layer (4). The second catalytic layer (4) is located on the base (1).

Fig. 8 shows an oxidation catalyst having an entrapment zone (2) located on the first catalyst layer (3). The first catalytic layer (3) is located on the second catalytic layer (4). The second catalytic layer (4) is located on the base (1).

Fig. 9 is a schematic diagram showing the layout of the exhaust system of the present invention. The exhaust gases (20) pass through the oxidation catalyst (1) according to the present invention, which has an entrainment material (2) located on the surface of the inlet end of the base. After the exhaust gases (20) have passed through the oxidation catalyst (1), they can pass through a second emission control device (10), such as a catalyzed particulate filter (CSF), a diesel particulate filter (DPF), a catalytic converter selective catalytic reduction (SCR) or selective catalytic reduction filter catalyst (SCRF ^TM ). If the second emission control device (10) is a selective catalytic reduction (SCR) catalyst or a selective catalytic reduction (SCRF ^TM ) filter catalyst and active selective catalytic reduction (SCR) is to be performed, then the exhaust system may contain an ammonia source ( 30) for injection into exhaust gases. In the case of passive selective catalytic reduction SCR, the source of ammonia (30) may not be available.

Fig. 10 shows an oxidation catalyst having a catalytic region (3) disposed on a base (1). There is a grip surface (2) located on the surface of the inlet end of the base (1).

Fig. 11 shows an oxidation catalyst having a catalytic region (3) disposed on a base (1). There is a capture surface and a zone (2) located or deposited on the surfaces of the inlet end of the base, which partially cover the catalytic region (3).

Fig. 12 is a graph showing the percent NO ₂ to NO _x output of the catalysts of Examples 1 and 2 after a series of test runs where they were exposed to sulfur.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in more detail. The sections below refer to the features of the present invention, especially the features of the oxidation catalyst of the present invention, and define each feature in more detail. Each part or feature of the oxidation catalyst (eg, entrapment material, catalytic region, location of the oxidation catalyst, base, etc.) may be combined with any other part or feature of the oxidation catalyst, unless expressly stated otherwise. In particular, any feature or features indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

The present invention relates to an entrainment material for capturing or trapping at least one sulfur-containing contaminant in exhaust gases generated by a diesel engine. The entrapment material may be included as part of a trap area, which may be positioned in various ways to trap or trap at least one sulfur-containing contaminant.

The expression "capture material for capturing at least one sulfur-containing impurity in exhaust gases generated by a diesel engine" is presented herein below as the abbreviated term "capture material".

The entrainment material contains or consists essentially of a metal to react with sulfur oxide in the exhaust gases and particles of a refractory oxide. The expression "metal to react with sulfur oxide in exhaust gases" is presented herein below as an abbreviated term "metal to capture S".

The trap metal S is typically placed on or deposited on the refractory oxide. The S trap metal can be placed directly on or directly deposited on the refractory oxide (eg, there is no intermediate carrier material between the S trap metal and the refractory oxide). The S trap metal is deposited on the refractory oxide by spreading over the surface of the refractory oxide, more preferably by dispersing and/or fixing on the surface of the refractory oxide.

At least one of the S trapping metal particles may be placed or deposited on at least one refractory oxide particle. Preferably, a plurality of S trapping metal particles are placed on or applied to at least one refractory oxide particle. More preferably, there is a plurality of refractory oxide particles, where a plurality of metal particles to trap S are placed or deposited on each refractory oxide particle.

The metal to capture S can reversibly react with sulfur oxide in the exhaust gases. At normal operating temperatures, sulfur oxides react with the metal to trap S to reduce or prevent poisoning of the catalyst region or catalyst component downstream of the emission control device. Trapping metal S has a limited ability to trap or trap sulfur oxides. In order to regenerate the capture material, it is possible to thermally release trapped or trapped sulfur oxides from the S capture metal. solid particles).

The S trapping metal may be selected from palladium (Pd), magnesium (Mg), cerium (Ce), and combinations of any two or more of these metals. Preferably, the S trap metal is palladium (Pd).

It is preferred that the metal particles to capture S have an average particle size of ≥ about 10 nm, such as an average particle size of > about 10 nm. More preferably, the S trap metal particles have an average particle size of ≥ about 15 nm, such as ≥ about 20 nm, even more preferably ≥ about 50 nm, such as ≥ about 75 nm.

Some of the S scavenging metals may be included in the oxidation catalyst to provide or improve catalytic activity. The average particle size of such metals (eg palladium) in conventional emission control devices is typically much smaller than 10 nm. The metal particles to capture S for use in the capture material in accordance with the present invention can be relatively large. Surprisingly, it has been found that such large S scavenging metal particles are capable of trapping or trapping sulfur oxide from exhaust gases, despite being relatively catalytically inert.

Typically, the S trap metal has an average particle size of 10 nm to 1000 microns. It is preferred that the S trap metal has an average particle size of 15 nm to 100 microns, more preferably 20 nm to 20 microns, especially 50 nm to 5 microns, such as 75 nm to 3 microns.

"Average particle size" as used herein in relation to the S scavenge metal, especially when the S scavenge metal is palladium, can be determined by CO chemisorption as set forth below. The metal content to capture S can be measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). The CO uptake of a sample can be measured using a Micromeritics Autochem 2920 device. The sample is pretreated with hydrogen gas at 300°C. Carbon monoxide uptake is measured by pulsed chemisorption at 50°C. The trapping metal particle size S can then be calculated using Autochem 2920 software from the CO uptake and trapping metal S content of the sample. The chemisorption ratio for the CO:Pd ratio of 1:1 is used in the calculation.

The refractory oxide may be selected from the group consisting of alumina, silica, titanium dioxide, zirconia, cerium oxide, and mixed or composite oxides thereof, such as mixed or composite oxides of two or more of these oxides. For example, the refractory oxide may be selected from the group consisting of alumina, silica, titania, zirconia, cerium oxide, silica-alumina, titania-alumina, zirconia-alumina, cerium-alumina , titanium dioxide-silicon dioxide, zirconia-silicon dioxide, zirconia-titanium dioxide, cerium oxide-zirconia and alumina-magnesium oxide.

The refractory oxide may optionally be doped (eg, with a dopant). The dopant may be selected from the group consisting of zirconium (Zr), titanium (Ti), silicon (Si), yttrium (Y), lanthanum (La), praseodymium (Pr), samarium (Sm), neodymium (Nd), and their oxides. The inclusion of a dopant can thermally stabilize the refractory oxide. It should be understood that any reference to "doped" in this context refers to a material in which the refractory oxide bulk or main lattice is doped by dopant replacement or incorporation. In some cases, small amounts of dopant may be present on the surface of the refractory oxide. However, the majority of the dopant will typically be present in the bulk of the refractory oxide.

When the refractory oxide is doped, the total amount of dopant is 0.25 to 5% by weight, preferably 0.5 to 3% by weight (eg, about 1% by weight) based on the weight of the refractory oxide.

It is generally preferred that the refractory oxide is undoped.

It is preferred that the refractory oxide is selected from the group consisting of alumina, silica, cerium oxide, silica-alumina, cerium-alumina, cerium-zirconia and alumina-magnesium oxide. More preferably, the refractory oxide is selected from the group consisting of alumina, cerium oxide, silica-alumina and cerium oxide-zirconia. More preferably, the refractory oxide is alumina, especially α-alumina.

Refractory oxide particles typically have an average specific surface area of ≤ about 50 m ² /g (< about 50 m ² /g), such as ≤ about 40 m ² /g (< about 40 m ² /g), preferably ≤ about 30 m ² /g (< about 30 m ² /g), more preferably ≤ about 20 m ² /g (< about 20 m ² /g), even more preferably ≤ about 10 m ² /g (< about 10 m ² /g ).

The average specific surface area (SSA) of the refractory oxide particles can be determined by nitrogen physical adsorption at -196° C. using a volumetric method. The mean specific surface area (SSA) is determined using the BET isothermal adsorption equation.

The refractory oxide particles may have a d90 <100 microns. The refractory oxide particles may preferably have a d90 of <75 microns, such as <50 microns (eg, <30 microns) and more preferably <20 microns, such as <15 microns. When the refractory oxide has a lower d90 value, improved bonding and adhesion can be achieved.

As known in the art, d90 is the particle size value at which 90% of the particles in the size distribution have a particle size less than this value. To avoid uncertainty, d90 measurements can be obtained by laser diffraction particle size analysis using the Malvern Mastersizer 2000, which is a volume based method (i.e. D90 can also refer to DV90 (or D(v,0.90)) and apply the model of mathematical theory Mie (Mie) to determine the particle size distribution.

Typically, the refractory oxide particles have a d90 >0.1 micron. It is preferred that the refractory oxide particles have a d90 >1.0 micron, eg >5.0 micron.

The refractory oxide particles for use in accordance with the present invention have a relatively low average specific surface area compared to the average specific surface area of the same refractory oxide particles used as a carrier material (e.g. for a catalytically active metal such as a platinum group metal). ) for prior art emission control devices (e.g. diesel oxidation catalyst (DOC), catalyzed diesel particulate filter (CSF) or NO _x storage catalyst (NSC)). Typically, small refractory oxide particles having a large average specific surface area are used in an emission control device to maximize catalytic activity. In contrast, the refractory oxide particles for use in the present invention are relatively large (ie typically much larger than those used as carrier material in prior art emission control devices).

Refractory oxides having an average specific surface area of ≤ about 50 m ² /g are known in the art and may be commercially available. It is also possible to obtain such a refractory oxide by heating a refractory oxide having an average specific surface area >50 m ² /g to a high temperature, usually a temperature (for example, 1200° C. or more), which is significantly higher than the temperature of the refractory oxide, which occurs in a vehicle's exhaust system during normal use. Accordingly, a refractory oxide (ie, having a small surface area) is not generated in situ during normal use of the oxidation catalyst.

The oxidation catalyst may include a trapping region for trapping at least one sulfur-containing contaminant in exhaust gases generated by a diesel engine. The expression "capture area for capturing at least one sulfur-containing impurity in the exhaust gases generated by a diesel engine" is presented herein below as the abbreviated term "capture area".

The grip area may comprise or consist essentially of grip material.

Typically, the capture area of at least one sulfur-containing impurity in the exhaust gases generated by a diesel engine has a load of refractory oxide from 0.1 to 3.5 g.in ^-3 (0.006-0.21 g/cm ³ ), preferably from 0 .2 to 2.5 g in ^-3 (0.012-0.153 g/cm ³ ), even more preferably 0.3 to 2.0 g in ^-3 (0.018-0.122 g/cm ³ ), and even more preferably 0.5 to 1.75 g in ^-3 (0.03-0.107 g/cm ³ ) (for example, 0.75 to 1.5 g in ^-3 (0.046-0.092 g/cm ³ )).

Typically, the grip area has a total S trap metal loading (eg, S trap metal content) of 1 g ft ^-3 to 50 g ft ^-3 (35.3-1766 g/m ³ ), preferably 4 g ft ^-3 up to 40 g ft ^-3 (141-1413 g/m ³ ), even more preferably 5 g ft ^-3 to 30 g ft ^-3 (177-1059 g/m ³ ).

The grip area may further comprise platinum. Platinum is not easily poisoned by sulfur oxides and can be included in some oxidation catalyst locations to provide additional functionality such as NO ₂ generation via NO oxidation.

When the grip region contains platinum, it is preferred that the grip region be located at or near the outlet end of the substrate.

Typically, the capture area contains particles of platinum (Pt) having an average particle size of <10 nm, preferably ≤8 nm.

The platinum particles may be placed or deposited on a refractory oxide (eg, gripping material). The platinum particles can be placed or deposited on the refractory oxide by dispersing over the surface of the refractory oxide, more preferably by spreading over the surface and/or fixing on the surface of the refractory oxide. When the platinum particles are placed on the refractory oxide, the platinum is part of the entrapment material, although it does not significantly contribute to the capture or entrapment of sulfur oxide.

In addition or alternatively, the grip area may contain platinum, preferably platinum particles such as described above. The platinum may be placed or deposited on the carrier material, separate from the refractory oxide of the entraining material. The carrier material for platinum is herein referred to as "Pt carrier material". This is to distinguish it from other carrier materials that may be present in the oxidation catalyst.

The Pt carrier material is a refractory oxide typically having an average specific surface area of ≥75 m ² /g, such as ≥100 m ² /g and preferably ≥100 m ² /g.

The refractory oxide of the carrier material Pt is selected from the group consisting of alumina, silicon dioxide, titanium dioxide, zirconium dioxide, cerium oxide, and mixed or complex oxides thereof, such as mixed or complex oxides of two or more of these oxides. For example, the refractory oxide may be selected from the group consisting of alumina, silica, titania, zirconia, cerium oxide, silica-alumina, titania-alumina, zirconia-alumina, cerium-alumina , titanium dioxide-silicon dioxide, zirconia-silicon dioxide, zirconia-titanium dioxide, cerium oxide-zirconia and alumina-magnesium oxide. It is preferred that the refractory oxide of the Pt carrier material contain or consist essentially of alumina or silica-alumina.

Typically, the grip area contains at least 50% by weight of the gripping material, preferably at least 75% by weight of the gripping material, preferably at least 90% by weight of the gripping material.

This invention includes oxidation catalysts where the capture material and the catalytic region are located in different ways. The optimum location of the entrainment material on the substrate can be determined by the chemistry and location of the oxidation catalyst catalytic material, and the chemistry and location of any downstream emission control device. For example, if it is desired to protect the oxidation catalyst catalyst material from sulfur oxides, this can be achieved by arranging the entrainment material to contact the exhaust gases prior to bringing the exhaust gases into contact with the catalyst material. If it is desired to protect the emission control device (e.g., Cu-containing selective catalytic reduction (SCR) catalyst or selective catalytic reduction (SCRF ^TM ) filter catalyst) located immediately downstream of the oxidation catalyst, then this can be achieved by positioning an entraining material for contact with exhaust gases before exhaust gases are discharged from the oxidation catalyst.

In the first to third oxidation catalyst arrangements below, the catalytic region preferably does not contain entraining material.

Typically, in the first to third positions of the oxidation catalyst, the oxidation catalyst comprises a base, an entrapment area containing an entrapment material, and a catalyst area located on the base.

For the avoidance of doubt, the capture region and the catalytic region have different compositions.

The catalytic region is typically positioned on or applied to a support. The catalytic region may be directly placed or deposited on the support (ie, the catalytic region is in contact with the surface of the support).

The capture area can be:

(a) placed or applied to the catalytic region; and/or

(b) placed directly on or applied to the substrate [i.e. the capture area is in contact with the base surface]; and/or

(c) in contact with the catalytic region [i.e. the capture region is adjacent to or adjacent to the catalytic region].

Typically, the catalytic region is located or deposited on the walls of a plurality of channels within the substrate (ie, on the wall of each channel within the substrate). The grip area is typically also located or applied to the walls of a plurality of channels in the base (ie, on the wall of each channel within the base).

In the first location of the oxidation catalyst, the capture region is the capture layer. The catalytic region may be a catalytic bed or a first catalytic zone and a second catalytic zone.

The capturing layer typically extends substantially the full length of the backing, especially the full length of the channels of the monolithic backing. See, for example, FIG. 1 and 2.

The gripping layer may consist essentially of a gripping material. It is preferred that the gripping layer preferably consists essentially of a gripping material (ie, a single gripping material).

The catalytic region may be a catalytic layer, preferably a single catalytic layer.

When the catalytic region is a catalytic layer (see FIG. 1), then the capturing layer can be placed on the catalytic layer, and the catalytic layer can be placed or applied (eg, directly located or deposited) on the support. Alternatively, the catalytic layer may be placed on the capturing layer and the capturing layer may be placed or applied (eg, directly located or deposited) on the substrate.

When the catalytic region is a catalyst bed, the catalyst layer preferably extends substantially the entire length of the substrate, especially the entire length of the channels of the monolithic substrate.

It is preferred that the capture layer is positioned or deposited (eg, directly positioned or deposited) on the catalyst layer, and the catalyst layer is positioned or deposited (eg, directly positioned or deposited) on the substrate. In this arrangement, the exhaust gases are brought into contact with the entrainment bed before they are brought into contact with the catalytic bed. Such an arrangement may be advantageous for protecting the oxidation catalyst catalyst material and also any downstream emission control device that has catalyst material susceptible to sulfur poisoning.

The catalytic region may be a first catalyst layer and a second catalyst layer, such as the second catalyst layer defined herein below. The catalytic layer described above is referred to below as the "first catalytic layer".

It is preferred that the capture layer is positioned or deposited (eg, directly positioned or deposited) on the first catalyst layer. More preferably, the first catalyst layer is positioned or deposited (eg, directly positioned or deposited) on the second catalyst layer, and the second catalyst layer is positioned or deposited (eg, directly positioned or deposited) on the substrate.

When the oxidation catalyst comprises a second catalyst layer, it is preferred that the first catalyst layer contains a carrier material that is sulfur tolerant, such as described below.

In the first location of the oxidation catalyst, the catalytic region may be the first catalytic zone and the second catalytic zone (see Fig. 3). The capture layer is preferably located or applied to both of the first catalyst zone and the second catalyst zone, more preferably the capture layer is directly located or applied to both of the first catalyst zone and the second catalyst zone.

The first catalytic zone and the second catalytic zone are preferably located or supported on the support, more preferably directly located or applied on the support.

The first catalytic zone typically has a length of 2.5 to 90% (e.g., 2.5 to 50% or 50 to 90%) of the base length, preferably 5 to 80% (e.g., 5 to 45% or 45 up to 80%), especially from 10 to 75% (for example, from 10 to 40% or from 40 to 75%) of the warp length, more preferably from 15 to 65% (for example, from 15 to 30% or from 30 to 65% ) the length of the warp.

It may be preferred that the first catalytic zone has a length of 2.5 to 10% of the length of the substrate, such as 2.5 to 7.5% or 5 to 10% of the length of the substrate. It is further preferred that the first catalyst zone has a total platinum group metal loading that is greater than the total platinum group metal loading of the second catalyst zone.

Typically, the second catalyst zone has a length of 10 to 90% of the length of the substrate (e.g., 50 to 90%), preferably 15 to 80% of the length of the substrate (e.g., 55 to 80%), more preferably 20 to 75% ( eg 30 to 65% of the warp length, even more preferably 30 to 65%.

It is generally preferred that the first catalyst zone is located or applied upstream of the second catalyst zone. More preferably, the first catalyst zone is placed or deposited at or near the inlet end of the substrate.

The first catalytic zone may be adjacent to the second catalytic zone. Preferably, the first catalytic zone is in contact with the second catalytic zone. When the first catalyst zone is adjacent to the second catalyst zone, or the first catalyst zone is in contact with the second catalyst zone, then the first catalyst zone and the second catalyst zone may be placed or deposited on the substrate as a layer (e.g., as a single layer). Accordingly, a layer (eg, a single layer) can be formed on the substrate when the first and second catalyst zones are adjacent to one another or in contact with one another.

The first catalytic zone may be separated from the second catalytic zone. There may be a gap (eg space) between the first catalyst zone and the second catalyst zone.

Alternatively, the first catalyst zone may overlay the second catalyst zone. The end section or part of the first catalytic zone can be placed or deposited on the second catalytic zone. The first catalytic zone usually only partially covers the second catalytic zone.

It may generally be preferred that the first catalyst zone contains a carrier material that is sulfur tolerant, such as described below.

In the second location of the oxidation catalyst, the trap area is the trap zone.

Typically, the capture zone has a length of ≥25 mm.

In addition or alternatively, the grip zone typically has a length of 2.5 to 90% (e.g., 2.5 to 50% or 50 to 90%) of the length of the warp, preferably 5 to 80% (e.g., 5 to 45% or 45 to 80%), especially 10 to 75% (e.g. 10 to 40% or 40 to 75%) of the warp length, more preferably 15 to 65% (e.g. 15 to 30% or from 30 to 65%) of the warp length.

The gripping zone may consist essentially of gripping material. It is preferred that the gripping zone preferably consists essentially of gripping material (ie, one gripping material).

The capture zone may be located or applied at or near the inlet end of the substrate (see, for example, FIGS. 3-6). More preferably, the capture zone is placed or applied directly at or near the inlet end of the substrate. Such arrangements may be advantageous for protecting the oxidation catalyst catalyst material from sulfur oxide poisoning.

Alternatively, the capture zone may be located or applied at or near the outlet end of the substrate. More preferably, the capture zone is placed or applied directly at or near the outlet end of the substrate. Such arrangements may be advantageous in protecting the downstream emission control device from sulfur oxide poisoning.

When the trap zone is located or deposited at or near the inlet end or outlet end of the substrate, the catalytic region may be:

(i) catalytic layer (see Fig. 5); or

(ii) catalytic zone (see Fig. 3 and 6); or

(iii) a first catalytic zone and a second catalytic zone (see Fig. 4); or

(iv) the first catalytic zone and the second catalytic layer (see Fig. 7); or

(v) the first catalytic layer and the second catalytic layer (see Fig. 8).

In case (i), the catalytic region is a catalytic layer, preferably a single catalytic layer. The trap zone is typically located or applied (eg, directly located or applied) on the catalytic layer (see Fig. 5).

The trap zone is preferably located or deposited on the catalyst layer, such as at or near the inlet end of the substrate (see FIG. 5) or at or near the outlet end of the substrate.

More preferably, the entrapment zone is directly located or deposited on the catalytic layer. When the entrapment zone is directly located or deposited on the catalyst layer at or near the inlet end of the substrate, the exhaust gases are brought into contact with the entrapment zone before they are brought into contact with a large portion of the catalyst layer.

When the catalytic region is a catalyst bed, the catalyst layer preferably extends substantially the full length of the support, especially the full length of the channels of the monolithic support.

The catalytic layer is preferably positioned or deposited (eg, directly positioned or deposited) on the support.

When the entrapment zone is located or deposited on the catalyst layer, it is preferred that the full length of the trap zone is located or deposited on the catalyst layer. The length of the capture zone is less than the length of the catalytic layer.

In case (ii), the catalytic region is a catalytic zone, preferably a single catalytic zone.

The catalytic zone is preferably located or deposited (eg, directly located or deposited) on the support.

The catalytic zone may be located or deposited (eg directly located or deposited) at or near the outlet end of the substrate. It is preferred that the grip zone is located or applied (eg, directly located or applied) to the substrate. More preferably, the capture zone is located or applied (eg directly located or applied) at or near the inlet end of the substrate.

Alternatively, the catalytic zone may be located or deposited (eg directly located or deposited) at or near the inlet end of the substrate. It is preferred that the grip zone is located or applied (eg, directly located or applied) to the substrate. More preferably, the capture zone is located or applied (eg directly located or applied) at or near the outlet end of the substrate.

Typically, the catalytic zone has a length of 10 to 90% of the length of the substrate (e.g. 50 to 90%), preferably 15 to 80% of the length of the substrate (e.g. 55 to 80%), more preferably 20 to 75% (e.g. , from 30 to 65%) of the warp length, even more preferably from 30 to 65%.

The catalytic zone may be adjacent to the capture zone. Preferably, the catalytic zone is in contact with the capture zone. When the catalytic zone is adjacent to the trapping zone, or the catalytic zone is in contact with the trapping zone, the catalytic zone and the trapping zone can be placed or deposited on the substrate in the form of a layer (for example, in the form of a single layer). Accordingly, a layer (eg, a single layer) can be formed on the substrate when the catalytic zone and the capture zone are adjacent to one another or are in contact with one another (see, for example, Fig. 3).

In addition, the capture zone may cover the catalytic zone. The end section or part of the capture zone can be placed or deposited on the catalytic zone (see, for example, Fig. 6). The capture zone may only partially cover the catalytic zone.

In an alternative arrangement (ii), the catalytic zone may be separated from the capture zone. There may be a gap (eg space) between the catalytic zone and the capture zone. The gap between the catalytic zone and the capture zone can be less than 10 mm (eg relatively small) or ≥10 mm.

In case (iii), the catalytic region is the first catalytic zone and the second catalytic zone.

The first catalyst zone is typically located or deposited (eg, directly located or deposited) on the second catalyst zone. Preferably, the second catalyst zone is located or applied (eg, directly located or applied) to the support.

The first catalytic zone and the second catalytic zone may both be located or deposited at or near the outlet end of the substrate (see FIG. 4).

Alternatively, the first catalyst zone and the second catalyst zone may both be located or deposited at or near the upstream end of the substrate.

Typically, the capture zone is located or applied (eg, directly located or applied) on the basis.

Typically, the first catalyst zone has a length of 10 to 90% of the length of the base (e.g., 50 to 90%), preferably 15 to 80% of the length of the base (e.g., 55 to 80%), more preferably 20 to 75% ( eg 30 to 65% of the warp length, even more preferably 30 to 65%.

The second catalyst zone typically has a length of 10 to 90% of the length of the substrate (e.g. 50 to 90%), preferably 15 to 80% of the length of the substrate (e.g. 55 to 80%), more preferably 20 to 75% (e.g. , from 30 to 65%) of the warp length, even more preferably from 30 to 65%.

When the catalytic region is the first catalytic zone and the second catalytic zone, it is preferred that the first catalytic zone contains a carrier material that is sulfur tolerant, such as described below.

In case (iv), the catalytic region is the first catalytic zone and the second catalytic layer.

The trap zone may be placed or deposited on the second catalyst layer at or near the upstream end of the substrate (see FIG. 7). More preferably, the entrapment zone is placed or deposited on the second catalyst layer at or near the upstream end of the substrate. In this arrangement, the exhaust gases are brought into contact with the entrapment zone before they are brought into contact with a large portion of the second catalyst bed.

Alternatively, the trap zone may be located or deposited on the second catalyst layer at or near the outlet end of the substrate. More preferably, a trap zone is placed on or deposited on the second catalyst layer at or near the outlet end of the substrate.

The second catalytic layer preferably extends substantially the full length of the base, especially the full length of the channels of the monolithic base.

The second catalytic layer is preferably positioned or deposited (eg, directly positioned or deposited) on the substrate.

When the entrapment zone is located or deposited on the second catalyst layer, it is preferred that the full length of the trap zone is located or deposited on the second catalyst layer. The length of the capture zone is less than the length of the second catalytic layer.

The first catalytic zone is preferably located or applied (eg, directly located or applied) on the second catalyst layer. More preferably, the first catalyst zone is located or deposited (eg, directly located or deposited) at or near the end of the substrate opposite the entrapment zone (eg, on the second catalyst layer), such as the outlet end or the inlet end.

Typically, the first catalyst zone has a length of 10 to 90% of the length of the base (e.g., 50 to 90%), preferably 15 to 80% of the length of the base (e.g., 55 to 80%), more preferably 20 to 75% ( eg 30 to 65% of the warp length, even more preferably 30 to 65%.

The trap zone may be located or deposited upstream of the first catalyst zone (eg, when the trap zone is located at or near the inlet end). In this arrangement, the exhaust gases are brought into contact with the capture zone before they are brought into contact with the first catalytic zone.

Alternatively, the entrapment zone may be located or deposited downstream of the first catalyst zone (eg, when the trap zone is located at or near the outlet end).

The first catalytic zone may be adjacent to the capture zone. Preferably, the first catalytic zone is in contact with the capture zone. When the first catalyst zone is adjacent to the trapping zone, or the first catalyst zone is in contact with the trapping zone, then the first catalyst zone and the trapping zone may be placed or deposited on the substrate in a layer (eg, as a single layer). Accordingly, a layer (eg, a single layer) can be formed on the substrate when the first catalytic zone and the capture zone are adjacent to one another or are in contact with one another.

In addition, the capture zone may cover the first catalytic zone. The end section or part of the capture zone can be placed or deposited on the first catalytic zone. The capture zone may only partially cover the catalytic zone.

Alternatively, the first catalytic zone may be separated from the capture zone. There may be a gap (eg space) between the first catalytic zone and the capture zone. The gap between the first catalytic zone and the capture zone may be less than 10 mm (eg relatively small) or ≥10 mm.

In case (v), the catalytic region is the first catalytic layer and the second catalytic layer.

The trap zone may be placed or deposited on the first catalyst layer at or near the upstream end of the substrate. More preferably, the capture zone is placed or supported on the first catalyst layer at or near the upstream end of the substrate. In this arrangement, the exhaust gases are brought into contact with the entrapment zone before they are brought into contact with a large portion of the first catalyst bed.

Alternatively, the trap zone may be located or deposited on the first catalyst layer at or near the outlet end of the substrate. More preferably, a trap zone is placed or supported on the first catalyst bed at or near the outlet end of the substrate.

The first catalyst layer may be placed or applied (eg, directly located or applied) on the second catalyst layer. The second catalytic layer may be positioned or deposited (eg, directly positioned or applied) on the substrate.

The first catalytic layer preferably extends substantially the full length of the base, especially the full length of the channels of the monolithic base.

The second catalytic layer preferably extends substantially the full length of the base, especially the full length of the channels of the monolithic base.

Generally, when the oxidation catalyst comprises a second catalyst layer, it is preferred that the first catalyst layer contains a carrier material that is sulfur tolerant, such as described below.

In the third arrangement of the oxidation catalyst, the base comprises an inlet end surface and an outlet end surface. The grip area is located or applied (eg, directly located or applied) on the surface of the inlet end and/or the surface of the outlet end (ie base), preferably on the surface of the inlet end, more preferably only on the surface of the inlet end. See FIG. 9 and 10.

In the third location of the oxidation catalyst, the trap area may be referred to as the "trap surface" because it is located on the surface of the substrate.

The gripping surface may consist essentially of gripping material. It is preferred that the gripping surface preferably consists essentially of the gripping material.

The gripping surface is preferably positioned or applied (eg, directly located or applied) to the surface of the inlet end of the substrate (ie, the surface of the upstream end of the substrate). The inlet end surface of the base typically includes a plurality of channel wall edges.

The inlet end surface of the base may be flat (eg, as in conventional honeycomb bases) or non-planar. When the inlet end surface of the base is non-planar, the inlet end surface may have a three-dimensional topographical configuration. Examples of substrates having a non-planar end surface are described in US 8257659. Substrates having non-planar end surfaces may provide increased surface area for the entrainment material to capture or trap at least one phosphorus-containing contaminant from exhaust gases.

It is generally preferred that the inlet end surface and/or the outlet end surface of the substrate be flat.

In addition to being positioned or applied to the surfaces of the inlet end of the base, the capture area may be placed or applied within the base, for example, on the walls of a plurality of channels or a catalytic region within the base. During application of the gripping surface, some gripping material may penetrate the channels of the substrate, thereby partially covering the walls of the channels within the substrate. See FIG. eleven.

When the trap area is located or deposited on the walls of a plurality of channels within the base, the oxidation catalyst further comprises a trap zone. The grip zone has the same composition as the grip surface (eg, the grip zone contains or consists essentially of grip material).

In the third oxidation catalyst location, the grip surface typically has an average length (e.g., from the inlet end of the substrate surface) <25 mm, preferably ≤20 mm, such as ≤15 mm, more preferably ≤10 mm (e.g., ≤5 mm) and more more preferably ≤3 mm (eg <3 mm). For the avoidance of doubt, the average length refers to the length in the axial direction of the base.

In the third location of the oxidation catalyst, the catalytic region is typically positioned or supported (eg directly located or supported) within the substrate, such as on the walls of a plurality of channels within the substrate.

The catalyst region may be either (i) a catalyst bed, (ii) a first catalyst layer and a second catalyst layer, or (iii) a first catalyst zone and a second catalyst zone.

When the catalyst region is (i) a catalyst layer, the catalyst layer may be placed or applied (eg, directly located or applied) to the substrate. The catalytic layer is preferably the only catalytic layer.

The catalytic layer preferably extends substantially the full length of the base, especially the full length of the channels of the monolithic base.

In case (ii), the catalytic region is the first catalytic layer and the second catalytic layer. It is preferred that the first catalyst layer is positioned or deposited (eg, directly positioned or deposited) on the second catalyst layer, and the second catalyst layer is positioned or deposited (eg, directly positioned or deposited) on the substrate.

Each of the first catalyst layer and the second catalyst layer preferably extends substantially the full length of the base, especially the full length of the channels of the monolithic base.

When the oxidation catalyst comprises a second catalyst layer, it is preferred that the first catalyst layer contains a carrier material that is sulfur tolerant, such as described below.

In case (iii), the catalytic region is the first catalytic zone and the second catalytic zone. The first catalytic zone and the second catalytic zone are preferably located or supported on the support, more preferably directly located or applied on the support.

The first catalytic zone typically has a length of 2.5 to 90% (e.g., 2.5 to 50% or 50 to 90%) of the base length, preferably 5 to 80% (e.g., 5 to 45% or 45 up to 80%), especially from 10 to 75% (for example, from 10 to 40% or from 40 to 75%) of the warp length, more preferably from 15 to 65% (for example, from 15 to 30% or from 30 to 65% ) the length of the warp.

Typically, the second catalyst zone has a length of 10 to 90% of the length of the substrate (e.g., 50 to 90%), preferably 15 to 80% of the length of the substrate (e.g., 55 to 80%), more preferably 20 to 75% ( eg 30 to 65% of the warp length, even more preferably 30 to 65%.

It is generally preferred that the first catalyst zone is located or applied upstream of the second catalyst zone. More preferably, the first catalyst zone is placed or deposited at or near the inlet end of the substrate.

The first catalytic zone may be adjacent to the second catalytic zone. Preferably, the first catalytic zone is in contact with the second catalytic zone. When the first catalyst zone is adjacent to the second catalyst zone, or the first catalyst zone is in contact with the second catalyst zone, then the first catalyst zone and the second catalyst zone may be placed or deposited on the substrate as a layer (e.g., as a single layer). Accordingly, a layer (eg, a single layer) can be formed on the substrate when the first and second catalyst zones are adjacent to one another or in contact with one another.

The first catalytic zone may be separated from the second catalytic zone. There may be a gap (eg space) between the first catalyst zone and the second catalyst zone.

Alternatively, the first catalyst zone may overlay the second catalyst zone. The end section or part of the first catalytic zone can be placed or deposited on the second catalytic zone. The first catalytic zone usually only partially covers the second catalytic zone.

It may generally be preferred that the first catalyst zone contains a carrier material that is sulfur tolerant, such as described below.

The composition of the catalytic region is described below. When a catalyst region is a first catalyst region (e.g., first catalyst bed or first catalyst zone) and a second catalyst region (e.g., second catalyst bed or second catalyst zone), then any reference to the composition of the "catalyst region" refers to the composition of the "first catalyst region". ". Accordingly, any reference below to "catalytic region" is equally applicable to the "first catalytic region".

The catalytic region contains a catalyst material containing a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd), and a combination of platinum (Pt) and palladium (Pd). The platinum group metal (PGM) may be Pt. The platinum group metal (PGM) may be Pd. The platinum group metal (PGM) may be a combination of Pt and Pd.

Typically, the catalytic material further comprises a carrier material. The catalyst material carrier material is referred to herein by the expression "catalyst material (CM) carrier material" or "first catalyst material (CM) carrier material" when "second catalyst material (CM) carrier material » is present. The platinum group metal (PGM) is preferably positioned or supported on a catalyst material (CM) support material. More preferably, the platinum group metal (PGM) is located or directly supported on the catalyst material (CM) carrier material (eg, no intermediate material between the platinum group metal (PGM) and the catalyst material (CM) carrier material) is present. For example, a platinum group metal (PGM) may be surface-distributed and/or impregnated into a catalyst material (CM) carrier material.

The carrier material for the catalytic material (CM) contains or consists essentially of a refractory oxide (referred to herein as a refractory oxide for the catalytic material). Refractory oxide particles typically have an average specific surface area of ≧75 m ² /g, such as ≧100 m ² /g and preferably ≧100 m ² /g.

The refractory oxide may be selected from the group consisting of alumina, silica, titanium dioxide, zirconia, cerium oxide, and a mixed or composite oxide of at least one of these refractory oxides. The refractory oxide may be selected from the group consisting of alumina, silica, titanium dioxide, zirconia, cerium oxide, silica-alumina, titanium dioxide-aluminum oxide, zirconia-alumina, cerium oxide-aluminum oxide, titanium-silicon dioxide, zirconia-silicon dioxide, zirconia-titanium dioxide, cerium oxide-zirconia-aluminum oxide and alumina-magnesium oxide.

Generally, it is preferred that the refractory oxide contains or consists essentially of alumina, silica or silica-alumina, especially alumina.

When the refractory oxide of the carrier material for the catalytic material (CM) contains or consists essentially of a mixed or composite oxide with alumina (for example, silica-alumina, alumina-magnesium oxide or a mixture of alumina and cerium oxide), then preferably mixed or the composite oxide with alumina contains at least 50 to 99 wt % alumina, more preferably 70 to 95 wt % alumina, even more preferably 75 to 90 wt % alumina.

When the refractory oxide of the carrier material for the catalytic material (CM) contains or consists essentially of cerium-zirconia oxide, then the cerium-zirconia oxide may consist essentially of 20-95% by mass of cerium oxide and 5-80% by mass zirconia (e.g. 50-95% by weight cerium oxide and 5-50% by weight zirconia), preferably 35-80% by weight cerium oxide and 20-65% by weight zirconia (e.g. 55-80% by weight by weight of cerium oxide and 20-45% by weight of zirconia), even more preferably 45-75% by weight of cerium oxide and 25-55% by weight of zirconia.

The refractory oxide of the carrier material for the catalytic material (CM) may optionally be doped (eg, with a dopant). The dopant may be selected from the group consisting of zirconium (Zr), titanium (Ti), silicon (Si), yttrium (Y), lanthanum (La), praseodymium (Pr), samarium (Sm), neodymium (Nd), and their oxides.

When the refractory oxide of the catalyst material carrier material (CM) is doped, the total amount of dopant is 0.25 to 5% by weight, preferably 0.5 to 3% by weight (eg, about 1% by weight).

The refractory oxide of the carrier material for the catalytic material (CM) may comprise or consist essentially of doped alumina. The alumina may be doped with a dopant containing silicon (Si), magnesium (Mg), barium (Ba), lanthanum (La), cerium (Ce), titanium (Ti), or zirconium (Zr), or a combination of two or more of these elements. . The dopant may contain or consist essentially of silicon oxide (for example, silicon dioxide), magnesium oxide (for example, magnesium oxide), lanthanum oxide (for example, lanthanum oxide), cerium oxide (for example, cerium oxide), titanium oxide (for example, titanium dioxide) or zirconia (eg zirconia). Preferably, the dopant contains or consists essentially of silicon, magnesium, cerium or their oxide, especially silicon or cerium or their oxide. More preferably, the dopant contains or consists essentially of silicon, magnesium or their oxide, especially silicon, magnesium or their oxide, especially silicon or its oxide.

When the alumina is alumina doped with silica, the alumina is doped with silica in a total amount of 0.5 to 45% by weight (i.e. % by weight based on alumina), preferably 1 to 40% by weight , more preferably 1.5 to 30% by weight (e.g. 1.5 to 10% by weight), particularly preferably 2.5 to 25% by weight, even more preferably 3.5 to 20% by weight (eg 5 to 20% by weight), even more preferably 4.5 to 15% by weight.

When the alumina is magnesium oxide doped alumina, the alumina is doped with magnesium oxide in an amount as defined above, or in an amount of 1 to 40% by weight (i.e., % by weight based on alumina), such as from 5 to 28% by weight. More preferably, the alumina is doped with magnesium oxide in an amount of 10 to 25% by weight.

It may be preferred that the refractory oxide of the carrier material for the catalytic material (CM) contains or consists essentially of titanium dioxide (TiO ₂ ). Titanium dioxide based support materials have been found to be sulfur resistant and can be advantageously used when the engine is running on fuels such as diesel or biodiesel having a high sulfur content.

The catalytic material may contain a single platinum group metal (PGM) (ie, which is only a platinum group metal). The only platinum group metal may be platinum. The only platinum group metal may be palladium.

When the platinum group metal (PGM) is a combination of platinum and palladium, then typically the catalytic region or its catalytic material based on them has a mass ratio of Pt to Pd from 20:1 to 1:20 (for example, from 15:1 to 1:15 ), preferably 10:1 to 1:10 (e.g. 7.5:1 to 1:7.5), more preferably 5:1 to 1:5 (e.g. 3:1 to 1:3) and even more preferably from 2.5:1 to 1:1.

It is generally preferred that the catalytic region or its catalytic material contains Pt and Pd, in which case the weight ratio of Pt to Pd is typically ≧1:1. The catalytic material may contain Pt and optionally Pd, so that the ratio by weight of Pt to Pd is from 1:0 to 1:1. The ratio by weight (i.e. weight ratio) of Pt to Pd is preferably 50:1 to 1:1, more preferably 30:1 to 2:1 (e.g. 25:1 to 4:1), even more preferably from 20:1 to 5:1, for example from 15:1 to 7.5:1.

It is preferred that when the catalyst region or its catalyst material contains Pt and Pd, the weight ratio of Pt to Pd is ≥1.5:1, more preferably ≥2:1 (for example, ≥3:1), even more preferably ≥ 4:1, e.g. ≥10:1.

Typically, the oxidation catalyst has a total loading of platinum group metal (PGM) from 5 to 500 g ft ^-3 (177-17657 g/m ³ ). Preferably, the total loading of platinum group metal (PGM) is from 10 to 400 g ft ^-3 (353-14126 g/m ³ ), more preferably from 20 to 350 g ft ^-3 (706-12360 g/m ³ ), still more preferably 40 to 300 g ft ^-3 (1413-10594 g/m ³ ) and even more preferably 50 to 250 g ft ^-3 (1766-8829 g/m ³ ).

It is generally preferred that the catalyst region or oxidation catalyst (eg, the overall emission control device) be substantially free of rhodium. More preferably, the catalytic region or oxidation catalyst does not contain rhodium. Rhodium is often included in ternary conversion catalysts or lean NO _x traps. The oxidation catalyst of the present invention is a diesel fuel oxidation catalyst, and it is mainly used for the oxidation of carbon monoxide and unburned hydrocarbons.

In addition or alternatively, the catalytic region or oxidation catalyst is essentially free of alkaline earth metal. More preferably, the catalytic region or oxidation catalyst does not contain an alkaline earth metal. When the capture material contains an alkaline earth metal, then the oxidation catalyst does not contain an alkaline earth metal other than the alkaline earth metal of the capture material. Alkaline earth metals are sometimes included in ternary conversion catalysts or lean NO _x traps.

The catalyst region or oxidation catalyst may be substantially free of hydrocarbon absorbing zeolite. More preferably, the catalytic region or oxidation catalyst does not contain a hydrocarbon absorbing zeolite. For heavy duty diesel applications, the inclusion of a hydrocarbon absorbing zeolite is not always necessary.

The second catalytic region typically contains or consists essentially of a platinum group metal (PGM) and carrier material. The carrier material of the second catalytic material is referred to herein by the expression "carrier material for the second catalytic material (CM)".

The platinum group metal (PGM) of the second catalytic region may be referred to herein as "second platinum group metal (PGM)" to distinguish it from the platinum group metal (PGM) of the "catalytic region" or "first catalytic region" described above.

The term "second" in the expression "second platinum group metal (PGM)" is a designation and does not limit the number of platinum group metals that must be present. Similarly, the second catalyst region carrier material may be referred to herein as "second catalyst material (CM) carrier material" to distinguish it from the "catalyst region" or "first catalyst region" carrier material described above. . The term "second" in the expression "second carrier material" is a designation and does not limit the number of supporting carrier materials that must be present.

The second platinum group metal (PGM) is preferably positioned or deposited on the carrier material for the second catalytic material (CM). More preferably, the second platinum group metal (PGM) is positioned or deposited directly on the second on the catalyst material (CM) carrier material (e.g., no intermediate material is present between the second platinum group metal (PGM) and the second catalyst material carrier material ( CM)). For example, a second platinum group metal (PGM) may be surface-distributed and/or impregnated into a carrier material for the second catalyst material (CM).

The second catalytic region typically has a different composition than the first catalytic region.

Preferably, the second catalytic region is substantially free of entraining material. More preferably, the second catalytic region does not contain entraining material.

Typically, the second catalyst region has a uniform composition (eg, a homogeneous composition).

The second platinum group metal (PGM) may be selected from the group consisting of platinum (Pt), palladium (Pd), and a combination of platinum (Pt) and palladium (Pd). The second platinum group metal (PGM) may be Pt. The second platinum group metal (PGM) may be Pd. The second platinum group metal (PGM) may be a combination of Pt and Pd.

The second catalytic region may contain a single platinum group metal (PGM) (ie, the second platinum group metal (PGM) is a single platinum group metal). The only platinum group metal may be platinum. The only platinum group metal may be palladium.

When the second platinum group metal (PGM) is a combination of platinum and palladium, then typically the second catalytic region has a weight ratio of Pt to Pd of 20:1 to 1:20 (e.g., 15:1 to 1:15), preferably 10 :1 to 1:10 (for example, from 7.5:1 to 1:7.5), more preferably from 5:1 to 1:5 (for example, from 3:1 to 1:3) and even more preferably from 2.5:1 to 1:1.

It may be preferred that the second catalytic region contains Pt and Pd in a weight ratio of Pt to Pd ≦4:1. The second catalytic region may contain Pd and optionally Pt, so that the ratio by weight of Pd to Pt is from 20:1 to 1:4. The weight ratio (ie weight ratio) of Pd to Pt is preferably 15:1 to 1:2, more preferably 10:1 to 1:1.5, even more preferably 5:1 to 1:1.

Typically, the second catalyst region has a total loading of the second platinum group metal (PGM) from 5 to 250 g ft ^-3 (177-8829 g/m ³ ). Preferably, the total loading of platinum group metal (PGM) is from 10 to 200 g ft ^-3 (353-7063 g/m ³ ), more preferably from 15 to 175 g ft ^-3 (530-6180 g/m ³ ), still more preferably 20 to 150 g ft ^-3 (706-5297 g/m ³ ) and even more preferably 25 to 125 g ft ^-3 (883-4414 g/m ³ ).

The carrier material for the second catalytic material (CM) contains or consists essentially of a refractory oxide. Refractory oxide particles typically have an average specific surface area of ≧75 m ² /g, such as ≧100 m ² /g and preferably ≧100 m ² /g.

The refractory oxide may be selected from the group consisting of alumina, silica, titanium dioxide, zirconia, cerium oxide, and a mixed or composite oxide of at least one of these refractory oxides. The refractory oxide may be selected from the group consisting of alumina, silica, titanium dioxide, zirconia, cerium oxide, silica-alumina, titanium dioxide-aluminum oxide, zirconia-alumina, cerium oxide-aluminum oxide, titanium-silicon dioxide, zirconia-silicon dioxide, zirconia-titanium dioxide, cerium oxide-zirconia and alumina-magnesium oxide.

It is preferred that the refractory oxide of the carrier material for the second catalytic material (CM) contains or consists essentially of alumina, silica or silica-alumina.

When the refractory oxide of the carrier material for the carrier material for the second catalytic material (CM) contains or consists essentially of a mixed or composite oxide with alumina (for example, silica-alumina, alumina-magnesium oxide, or a mixture of alumina and cerium oxide ), then preferably the mixed or composite oxide with alumina contains at least 50 to 99 wt % alumina, more preferably 70 to 95 wt % alumina, even more preferably 75 to 90 wt % alumina.

When the refractory oxide of the carrier material for the second catalyst material (CM) contains or consists essentially of cerium-zirconia oxide, then the cerium-zirconia oxide may consist essentially of 20-95% by weight of cerium oxide and 5-80% by weight. by weight of zirconia (for example, 50-95% by weight of cerium oxide and 5-50% by weight of zirconia), preferably 35-80% by weight of cerium oxide and 20-65% by weight of zirconia (for example, 55-80% by weight of cerium oxide and 20-45% by weight of zirconia), even more preferably 45-75% by weight of cerium oxide and 25-55% by weight of zirconia.

The refractory oxide of the carrier material for the second catalytic material (CM) may optionally be doped (eg, with a dopant). The dopant may be selected from the group consisting of zirconium (Zr), titanium (Ti), silicon (Si), yttrium (Y), lanthanum (La), praseodymium (Pr), samarium (Sm), neodymium (Nd), and their oxides.

When the refractory oxide of the carrier material for the second catalyst material (CM) is doped, the total amount of dopant is 0.25 to 5% by weight, preferably 0.5 to 3% by weight (eg, about 1% by weight).

The refractory oxide of the carrier material for the second catalytic material (CM) may comprise or consist essentially of doped alumina. The alumina may be doped with a dopant containing silicon (Si), magnesium (Mg), barium (Ba), lanthanum (La), cerium (Ce), titanium (Ti), or zirconium (Zr), or a combination of two or more of these elements. . The dopant may contain or consist essentially of silicon oxide (for example, silicon dioxide), magnesium oxide (for example, magnesium oxide), lanthanum oxide (for example, lanthanum oxide), cerium oxide (for example, cerium oxide), titanium oxide (for example, titanium dioxide) or zirconia (eg zirconia). Preferably, the dopant contains or consists essentially of silicon, magnesium, cerium or their oxide, especially silicon or cerium or their oxide. More preferably, the dopant contains or consists essentially of silicon, magnesium or their oxide, especially silicon, magnesium or their oxide, especially silicon or its oxide.

When the alumina is alumina doped with silica, the alumina is doped with silica in a total amount of 0.5 to 45% by weight (i.e. % by weight based on alumina), preferably 1 to 40% by weight , more preferably 1.5 to 30% by weight (e.g. 1.5 to 10% by weight), particularly preferably 2.5 to 25% by weight, even more preferably 3.5 to 20% by weight (eg 5 to 20% by weight), even more preferably 4.5 to 15% by weight.

When the alumina is magnesium oxide doped alumina, the alumina is doped with magnesium oxide in an amount as defined above, or in an amount of 1 to 40% by weight (i.e., % by weight based on alumina), such as from 5 to 28% by weight. More preferably, the alumina is doped with magnesium oxide in an amount of 10 to 25% by weight.

The second catalytic region may further comprise a hydrocarbon adsorbent. The hydrocarbon adsorbent is preferably a zeolite.

Examples of suitable zeolites or types of zeolite include faujasite, clinoptilolite, mordenite, silicalite, ferrierite, zeolite X, zeolite Y, ultra stable zeolite Y, zeolite AEI, zeolite ZSM-5, zeolite ZSM-12, zeolite ZSM-20, zeolite ZSM-34, CHA zeolite, SSZ-3 zeolite, SAPO-5 zeolite, offretite, beta zeolite or CHA copper zeolite. The zeolite is preferably ZSM-5 zeolite, beta zeolite or Y zeolite.

When the hydrocarbon adsorbent is a zeolite, then preferably the zeolite is a medium pore zeolite or a large pore zeolite.

When the second catalytic region contains a hydrocarbon adsorbent, then this second catalytic region has a total amount of hydrocarbon adsorbent from 0.05 to 3.00 g in ^-3 (3-183 mg cm ^-3 ), preferably from 0.10 to 2, 00 g·in ^-3 (6-122 mg·cm ^-3 ), more preferably from 0.2 to 0.8 g·in ^-3 (12-49 mg·cm ^-3 ). For example, the total amount of hydrocarbon adsorbent may be from 0.8 to 1.75 g/in ³ (49-107 mg/cm ³ ), for example, from 1.0 to 1.5 g/in ³ (61-92 mg/cm 3 ). cm ³ ).

It is generally preferred that the second catalyst region be substantially free of rhodium. More preferably, the second catalyst region does not contain rhodium.

In addition or alternatively, the second catalytic region is essentially free of alkaline earth metal. More preferably, the second catalytic region does not contain an alkaline earth metal.

It may be preferred that the second catalytic region is substantially free of hydrocarbon adsorbent, especially zeolite (eg, for absorbing hydrocarbons). More preferably, the second catalytic region does not contain a hydrocarbon adsorbent, especially a zeolite (for example, for absorbing hydrocarbons).

Typically (including any of the oxidation catalyst arrangements discussed above), the oxidation catalyst may be a diesel oxidation catalyst (DOC), a catalyzed diesel particulate filter (CSF), a diesel exothermic catalyst (DEC), a NOx storage _catalyst (NSC), or a passive absorber. NO _x (PNA). It is preferred that the oxidation catalyst is a diesel oxidation catalyst (DOC), a diesel exothermic catalyst (DEC), or a catalyzed diesel particulate filter (CSF). More preferably, the oxidation catalyst is a Diesel Oxidation Catalyst (DOC) or a Diesel Exothermic Catalyst (DEC), even more preferably the oxidation catalyst is a Diesel Oxidation Catalyst (DOC).

The basics for maintaining oxidation catalysts are well known in the art. Methods for making porous oxide washcoat coatings to apply a catalytic material or entrainment material to a substrate and methods for applying porous oxide washcoat coatings to a substrate are also known in the art, (see, for example, WO 99/47260, WO 2007/077462 and WO 2011/080525).

The base usually has a plurality of channels (for example, for the flow of exhaust gases through it). Typically, the base is a ceramic material or a metal material.

It is preferred that the substrate be made of or consist of cordierite (SiO ₂ -Al ₂ O ₃ -MgO), silicon carbide (SiC), Fe-Cr-Al alloy, Ni-Cr-Al alloy or stainless steel.

The support may, for example, be tubular, fibrous or particulate. Examples of suitable carrier substrates include monolithic cordierite honeycomb substrate, monolithic SiC honeycomb substrate, layered fiber or woven fabric substrate, foam substrate, cross flow substrate, mesh metal wire substrate, porous metal substrate and a base of ceramic particles.

Typically, the base is a monolith (also referred to herein as a monolithic base). Such monolithic supports are well known in the art.

The monolithic base may be a flow-through monolithic base. Alternatively, the base monolith may be a filter base monolith. It is preferred that the base monolith is a flow-through base monolith.

The flow-through body monolith is typically in the form of a honeycomb body (eg, a metal or ceramic honeycomb body) having a plurality of channels extending through it, these channels being open at both ends. When the substrate is a flow-through monolithic substrate, then the oxidation catalyst of this invention is typically a diesel oxidation catalyst (DOC), a diesel exothermic catalyst (DEC), a NO _x storage catalyst (NSC), or a passive NO _x absorber (PNA). It is preferred that the oxidation catalyst of this invention is a diesel oxidation catalyst (DOC).

The filter body typically comprises a plurality of inlets and a plurality of outlets, with the inlets open at the upstream end (i.e., exhaust gas inlet side) and plugged or closed at the downstream end (i.e., on the exhaust outlet side), the outlet passages are plugged or closed at the upstream end and open at the downstream end, and each inlet passage is separated from the outlet passage by a porous structure. When the base is a filter base monolith, then the oxidation catalyst of this invention is typically a catalyzed diesel particulate filter (CSF), a NO _x storage catalyst (NSC) on the filter, or a passive NO _x absorber (PNA) on the filter, preferably a catalyzed diesel particulate filter (CSF) .

When the substrate is a filter substrate, it is preferable that the filter substrate is a wall-flow filter. In a wall-flow filter, each inlet is in turn separated from the outlet by a wall of porous structure and vice versa. It is preferable that the inlets and outlets are arranged in a honeycomb structure. When arranged in a honeycomb structure, it is preferred that the ports vertically and laterally adjacent to the inlet port are plugged at the upstream end and vice versa (i.e. the ports vertically and laterally adjacent to the outlet port are plugged at the downstream end). When viewed from either end, the alternately closed and open ends of the channels have a checkerboard pattern.

When the oxidation catalyst of this invention is a catalyzed diesel particulate filter (CSF), then both the catalytic region (or catalytic bed or catalytic zone) and the entrainment region (or entrainment layer or entrainment zone) may be placed or coated on (i) the walls of a plurality of inlet passages the base and/or (ii) the walls of the plurality of outlet channels of the base.

Alternatively, it is preferred that when the oxidation catalyst of the present invention is a catalyzed diesel particulate filter (CSF), then a catalytic region (or catalytic layer or catalytic zone) is located or deposited on the walls of a plurality of exhaust ports of the base, and the entrapment area (or entrapment layer or capture zone) was located or applied on the walls of a plurality of inlet channels of the base.

The base, especially the monolithic base, preferably has a diameter of ≥7 inches (eg, ≥17.8 cm). Such monolithic bases are typically used for heavy duty diesel engine applications.

The volume of catalyst (eg, all coatings (ie, capture region, catalytic region) deposited on the monolithic support) is typically ≧2.0 L, more preferably ≧2.5 L.

The present invention further relates to an exhaust system for treating exhaust gases generated by a diesel engine. The exhaust system comprises an oxidation catalyst according to the present invention and an emission control device. The emission control device is preferably located downstream of the oxidation catalyst.

Examples of the emission control device include diesel particulate filter (DPF), NO _x storage catalyst (NSC), lean NO _x catalyst (LNC), selective catalytic reduction (SCR) catalyst, diesel oxidation catalyst (DOC), catalyzed diesel particulate filter (CSF), selective catalytic reduction filter catalyst (SCRF ^TM ), ammonia anti-slip catalyst (ASC), and combinations of two or more of these. Such emission control devices are all well known in the art.

Preferably, the exhaust system comprises an emission control device selected from the group consisting of NO _x storage catalyst (NSC), ammonia control catalyst (ASC), diesel particulate filter (DPF), selective catalyst catalytic reduction (SCR), catalyzed diesel particulate filter (CSF), selective catalytic reduction filter catalyst (SCRF ^TM ), and combinations of two or more of them. More preferably, the emission control device is selected from the group consisting of diesel exhaust particulate filter (DPF), selective catalytic reduction (SCR) catalyst, catalyzed diesel particulate filter (CSF), selective catalytic reduction filter (SCRF ^TM ) catalyst, and combinations of the two. them or more. Even more preferably, the emission control device is a selective catalytic reduction (SCR) catalyst or a selective catalytic reduction (SCRF ^TM ) filter catalyst.

Typically, when the exhaust system contains a selective catalytic reduction (SCR) catalyst or selective catalytic reduction (SCRF ^TM ) filter catalyst, the selective catalytic reduction (SCR) catalyst or selective catalytic reduction (SCRF ^TM ) filter catalyst contains Fe or Cu supported on molecular sieve such as described below, more preferably Cu supported on the molecular sieve.

When the exhaust system of the present invention comprises a selective catalytic reduction (SCR) catalyst or a selective catalytic reduction (SCRF ^TM ) filter catalyst, the exhaust system may further comprise an injector for injecting a nitrogen-containing reducing agent such as ammonia or an ammonia precursor such as as urea or ammonium formate, preferably urea, to the exhaust gases upstream of the selective catalytic reduction (SCR) catalyst or selective catalytic reduction (SCRF ^TM ) filter catalyst. Typically, the injector is downstream of the oxidation catalyst. Such an injector may be fluidly connected to a source (eg, reservoir) of the nitrogen-containing reductant precursor. Throttled dosing of the precursor into the exhaust stream can be adjusted by means of an engine control suitably programmed and a closed loop or open feedback loop provided with sensors controlling the composition of the exhaust gases. Ammonia can also be formed by heating ammonium carbamate (solid state), and the formed ammonia can be injected into the exhaust gases.

Alternatively, or in addition to the injector, ammonia can be generated on site (for example, during regeneration of the NO _x storage catalyst (NSC) located upstream of the selective catalytic reduction (SCR) catalyst or selective catalytic reduction filter catalyst (SCRF ^™ ) Accordingly, the exhaust system may further comprise an engine control means for enriching the exhaust gases with hydrocarbons.

The selective catalytic reduction (SCR) catalyst or selective catalytic reduction (SCRF ^TM ) filter catalyst may contain at least one metal selected from the group consisting of Cu, Hf, La, Au, In, V, lanthanides, and Group VIII transition metals ( for example, Fe), while this metal is deposited on a refractory oxide or molecular sieve. The metal is preferably selected from Ce, Fe, Cu and combinations of any two or more of these metals, more preferably the metal is Fe or Cu.

The refractory oxide for the selective catalytic reduction (SCR) catalyst or selective catalytic reduction (SCRF ^TM ) filter catalyst may be selected from the group consisting of Al ₂ O ₃ , TiO ₂ , CeO ₂ , SiO ₂ , ZrO ₂ and mixed oxides containing two them or more. The non-zeolitic catalyst may also include tungsten oxide (eg V ₂ O ₅ /WO ₃ /TiO ₂ , WO _x /CeZrO ₂ , WO _x /ZrO ₂ or Fe/WO _x /ZrO ₂ ).

It is especially preferred that the selective catalytic reduction (SCR) catalyst, the selective catalytic reduction (SCRF ^TM ) filter catalyst or porous oxide washcoat coating therewith contains at least one molecular sieve, such as an aluminosilicate zeolite or SAPO zeolite. The at least one molecular sieve may be a small, medium, or large pore size molecular sieve. By "small pore molecular sieve" in this document, we mean molecular sieves containing a maximum ring size of 8 atoms, such as CHA; by "medium pore molecular sieve" in this document we mean a molecular sieve containing a maximum ring size of 10 atoms, such as ZSM-5; and by "large pore molecular sieve" in this document, we mean a molecular sieve having a maximum ring size of 12 atoms, such as beta. Small pore size molecular sieves are potentially advantageous for use in selective catalytic reduction (SCR) catalysts.

In the exhaust system of this invention, the preferred molecular sieves for the selective catalytic reduction (SCR) catalyst or selective catalytic reduction (SCRF ^TM ) filter catalyst are synthetic aluminosilicate zeolite molecular sieves selected from the group consisting of AEI, ZSM-5, ZSM -20, ERI including ZSM-34, mordenite, ferrierite, BEA including beta, Y, CHA, LEV including Nu-3, MCM-22 and EU-1, preferably AEI or CHA, and having a silica to oxide ratio aluminum from about 10 to about 50, for example, from about 15 to about 40.

The oxidation catalyst of this invention is preferably directly connected (eg, directly downstream of it) to the exhaust manifold of a diesel engine. When the oxidation catalyst is directly connected to the exhaust manifold, there is no emission control device between the oxidation catalyst of the present invention and the exhaust manifold. Accordingly, the oxidation catalyst of the present invention is the first emission control device encountered by exhaust gases generated by a diesel engine.

The oxidation catalyst may be directly connected to the exhaust manifold of the diesel engine.

In the first location of the exhaust system, the exhaust system contains the oxidation catalyst of this invention and the selective catalytic reduction (SCRF ^TM ) filter catalyst. The oxidation catalyst of this invention (eg, upstream) is typically followed by a Selective Catalytic Reduction (SCRF ^TM ) filter catalyst.

The nitrogen-containing reductant injector may be located between the oxidation catalyst and the selective catalytic reduction (SCRF ^TM ) filter catalyst. Accordingly, an oxidation catalyst (eg, upstream) may be followed by a nitrogen reductant injector, and a given nitrogen reductant injector (eg, upstream) may be followed by a selective catalytic reduction filter (SCRF ^™ ) catalyst.

In a second exhaust system arrangement, the exhaust system comprises an oxidation catalyst of the present invention and a selective catalytic reduction (SCR) catalyst and optionally a catalyzed particulate filter (CSF) or diesel particulate filter (DPF). The oxidation catalyst (eg, upstream) is typically followed by a selective catalytic reduction (SCR) catalyst.

The nitrogen-containing reductant injector may be located between the oxidation catalyst and the selective catalytic reduction (SCR) catalyst. Accordingly, an oxidation catalyst (eg, upstream) may be followed by a nitrogen reductant injector, and a given nitrogen reductant injector (eg, upstream) may be followed by a selective catalytic reduction (SCR) catalyst. The selective catalytic reduction (SCR) catalyst (eg, upstream) may be followed by a catalyzed particulate filter (CSF) or a diesel particulate filter (DPF).

In a third exhaust system location, the exhaust system comprises an oxidation catalyst of the present invention and a catalyzed diesel particulate filter (CSF). An oxidation catalyst (eg upstream) is usually followed by a catalyzed diesel particulate filter (CSF). Accordingly, for example, the outlet of the oxidation catalyst is connected to the inlet of the catalyzed particulate filter.

In the fourth exhaust system location, the exhaust system contains the oxidation catalyst of the present invention, a catalyzed diesel particulate filter (CSF) and a selective catalytic reduction (SCR) catalyst. An oxidation catalyst (eg upstream) is usually followed by a catalyzed diesel particulate filter (CSF). A catalyzed particulate filter (eg upstream) is usually followed by a selective catalytic reduction (SCR) catalyst.

The nitrogen reductant injector may be located between the catalyzed particulate filter (CSF) and the selective catalytic reduction (SCR) catalyst. Accordingly, a catalyzed diesel particulate filter (CSF) (eg, upstream) may be followed by a nitrogen reductant injector, and a given nitrogen reductant injector (eg, upstream) may be followed by a selective catalytic reduction (SCR) catalyst.

In any of the embodiments of the first, second, or fourth exhaust system arrangement described herein above, an ammonia anti-slip catalyst (ASC) may be located downstream of the selective catalytic reduction (SCR) catalyst or filter catalyst. selective catalytic reduction (SCRF ^TM ) (i.e. as a separate monolithic support), or, more preferably, a zone downstream or adjacent to the end of the monolithic support containing a selective catalytic reduction (SCR) catalyst can be used as a support for Ammonia Prevention Catalyst (ASC).

The present invention further provides a vehicle. The vehicle comprises a diesel engine and an oxidation catalyst or exhaust system according to the present invention.

The diesel engine is typically a conventional (ie conventional) diesel engine.

The vehicle may be a light duty diesel vehicle (LDV), such as defined in US or European legislation. The diesel light duty vehicle typically has a mass of <2840 kg, more preferably a mass of <2610 kg.

In the US, a light duty diesel vehicle (LDV) refers to a diesel vehicle having a gross vehicle weight of ≤8500 lbs (US lbs) (≤3856 kg). In Europe, the term "light duty diesel vehicle (LDV)" refers to (i) passenger vehicles having no more than eight seats in addition to the driver's seat and having a maximum mass not exceeding 5 tons, and (ii) vehicles for the carriage of goods with a maximum mass not exceeding 12 tons.

Preferably, the vehicle is a heavy duty diesel vehicle (HDV), such as a diesel vehicle, having a gross vehicle weight of >8500 pounds (US lbs) (>3856 kg) as defined in US law.

Exhaust gases can be generated by a diesel engine running on diesel fuel (eg, conventional petroleum-derived diesel, often referred to as petroleum diesel) or biodiesel. The biodiesel may be B100 (e.g., 100% biodiesel) or it may be a mixture of biodiesel and petroleum diesel such as B6 to B20 (e.g., containing 6 to 20% biodiesel and 80 to 94% petroleum diesel fuel such as specified in ASTM D7467). Biodiesel fuel often contains sulfur-containing impurities.

It may be preferred that in the oxidation catalyst of this invention the carrier material of the catalytic region/first catalytic region is sulfur tolerant.

The diesel engine can be operated on diesel fuel containing ≤50 ^ppm sulphur, more preferably ≤15 ^ppm sulphur, such as ≤10 ^ppm sulphur, and even more preferably ≤5 ^ppm sulphur. Such diesel fuels are often referred to as "Ultra Low Sulfur Diesel" (ULSD).

Alternatively, the diesel engine may be run on a fuel, such as diesel fuel, containing >50 ^ppm sulfur, eg >200 ^ppm (eg, 250 to 2000 ^ppm ) sulfur. When a diesel engine runs on such diesel fuel, it may be preferable that in the oxidation catalyst of the present invention the carrier material of the catalytic region/first catalytic region is sulfur tolerant.

DEFINITIONS

The term "mixed oxide" as used herein generally refers to a mixture of oxides in a single phase, as is commonly known in the art. The term "complex oxide" as used herein generally refers to an oxide composition having more than one phase, as is commonly known in the art.

For the avoidance of doubt, the term "combination of platinum (Pt) and palladium (Pd)", as used herein in relation to a region, zone, or layer, refers to the presence of both platinum and palladium in a region, zone, or layer. The word "combination" does not require that platinum and palladium be present as a mixture or alloy, although such a mixture or alloy is covered by this term.

The acronym "PGM" as used herein refers to "platinum group metal". The term "platinum group metal" generally refers to a metal selected from the group consisting of Ru, Rh, Pd, Os, Ir and Pt, preferably a metal selected from the group consisting of Ru, Rh, Pd, Ir and Pt, unless otherwise indicated.

The expression "on the backing" as used herein in connection with an area, layer or zone that is "located or deposited on the backing" generally refers to the area, layer or zone that is placed on the surface of the channel wall within the backing, unless otherwise indicated.

The expression "end surface" as used herein, especially in relation to "inlet end surface" or "outlet end surface", is synonymous with the expression "end surface". The end surface or end surface of the warp is typically formed by the edges of the walls (eg, on the outer surface of the warp) that define or link channels throughout the warp.

The term "area" as used herein refers to the area on a substrate, typically obtained by drying and/or firing a washcoat porous oxide coating. An "area" may, for example, be placed or applied to a substrate as a "layer" or "zone". The area or location of the substrate is usually adjusted during the process of applying the porous oxide washcoat to the substrate. A "region" usually has distinct boundaries or edges (i.e., it is possible to distinguish one region from another using conventional analytical methods).

Typically, a "region" is substantially the same length. Reference to "substantially the same length" in this context refers to a length that does not deviate (for example, in relation to the difference between the maximum and minimum length) by more than 10%, preferably does not deviate by more than 5%, more preferably does not deviate more than 1% of its average value.

It is preferred that each "region" has a substantially uniform composition (i.e., there is no significant difference in composition when one part of the region is compared with another part of the region), unless the context dictates otherwise. More preferably, each zone or layer has a uniform composition (eg, a homogeneous composition). Substantially homogeneous composition in this context refers to a material (e.g., region) in which the difference in composition when comparing one part of the region with another part of the region is 5% or less, typically 2.5% or less, and most typically 1% or less.

The term "zone" as used herein refers to an area having a length that is less than the full length of the warp, for example ≤75% of the total length of the warp. The "zone" typically has a length (ie, substantially the same length) of at least 5% (eg, ≥5%) of the total length of the warp.

The overall length of the warp is the distance between its inlet end and its outlet end (eg, between opposite ends of the warp).

Any reference to "zone located at the inlet end of the substrate" as used herein refers to the zone placed or applied to the substrate when the zone is closer to the inlet end of the substrate than to the outlet end of the substrate. Accordingly, the midpoint of the zone (ie, at half its length) is closer to the inlet end of the warp than to the outlet end of the warp. Likewise, any reference to "a zone located at the outlet end of a substrate" as used herein refers to a zone placed or applied to the substrate when the zone is closer to the outlet end of the substrate than to the inlet end of the substrate. Accordingly, the midpoint of the zone (ie, at half its length) is closer to the outlet end of the warp than to the inlet end of the warp.

When the substrate is a wall-flow filter, then generally any reference to "zone located at the inlet end of the substrate" refers to a zone placed on or applied to the substrate that:

(a) closer to the inlet end (e.g., open end) of the base inlet than that zone is located in relation to the closed end (e.g., blocked or clogged end) of that inlet, and/or

(b) closer to the closed end (eg, blocked or plugged end) of the base outlet than that zone is located in relation to the outlet end (eg, open end) of that outlet.

Accordingly, the midpoint of the zone (i.e. half its length) is (a) closer to the inlet end of the warp inlet than to the closed end of the inlet and/or (b) closer to the closed end of the warp outlet than to the outlet end of the outlet channel.

Similarly, any reference to a "zone located at the outlet end of a substrate" when the substrate is a wall-flow filter refers to a zone located or applied to the substrate that:

(a) closer to the outlet end (e.g., open end) of the base outlet than that zone is located in relation to the closed end (e.g., blocked or plugged end) of that outlet, and/or

(b) closer to the closed end (eg, blocked or clogged end) of the base inlet than that zone is located in relation to the inlet end (eg, open end) of that inlet.

Accordingly, the midpoint of the zone (i.e., at half its length) is (a) closer to the outlet end of the warp outlet than to the closed end of the outlet, and/or (b) closer to the closed end of the warp inlet than to the inlet. end of the inlet.

The zone may satisfy both (a) and (b) when the porous oxide "washcoat" coating is present as a filter wall with flow through the walls (ie, the zone is an inner wall).

The expression "consist essentially of" as used herein is intended to limit the scope of a feature to include specific materials or steps and any other materials or steps that do not substantially affect the underlying characteristics of that feature, such as, for example, minor impurities. The expression "consist essentially of" encompasses the expression "consist of".

The expression "substantially free" as used herein when referring to a material, generally referring to the component content of a porous oxide washcoat region, a porous oxide washcoat layer, or a porous oxide washcoat zone , means that this material is contained in a small amount, such as ≤5% by mass, preferably ≤2% by mass, more preferably ≤1% by mass. The expression "substantially does not contain" encompasses the expression "does not contain".

The expression "about", as used herein in relation to the end point of the interval of numerical values, includes the exact end point of the specified interval of numerical values. Accordingly, for example, an expression defining a parameter as up to "about 0.2" includes a parameter up to and including 0.2.

The term "selective catalytic reduction filter catalyst" as used herein includes a selective catalytic reduction composition that has been coated on a diesel exhaust particulate filter (SCR-DPF), which is known in the art.

EXAMPLES

The invention will now be illustrated by the following non-limiting examples.

Example 1

The first slurry was prepared by grinding alumina powder in water to d90 <20 microns. Soluble salts of platinum and palladium were added at a weight ratio of platinum to palladium of 1:1.

The resulting porous oxide "washcoat" coating was applied to the inlets of the flowing cordierite throughout the warp using conventional coating techniques.

The depth of this porous oxide washcoat was up to 80% of the length of the substrate. This part was dried. A second slurry was prepared by grinding alumina powder in water to d90 <20 microns. The soluble platinum salt was then added and the suspension stirred to homogenize it. The resulting porous oxide "washcoat" coating was applied to the outlet channels of the flowing cordierite throughout the warp using conventional coating techniques. The thickness of this porous oxide washcoat was up to 80% of the length of the substrate. The prototype was dried and fired at 500°C.

Soluble salts of platinum and palladium were mixed at a mass ratio of platinum to palladium 1:1 and diluted with water. The solution was applied to the inlet channels of the cordierite base using conventional coating methods. The coating depth was up to 25% of the base length. This part was dried. The loading of platinum group metal (PGM) in this coating was 35 g ft ^-3 (1236 g/m ³ ).

The sulfur trapping coating was made by suspending alpha alumina powder (low specific surface area) in water and grinding to d90 <20 microns. A soluble palladium salt was added to the slurry, followed by the addition of ascorbic acid. The mixture was stirred to homogenize it. The resulting porous oxide "washcoat" coating was applied to the outlet channels of the flow base using conventional coating techniques. The thickness of this porous oxide washcoat was 50% of the length of the substrate. The loading of palladium in this porous oxide washcoat was 20 g ft ^-3 (706 g/m ³ ). The prototype was dried and fired at 500°C. The loading of platinum group metal (PGM) in the diesel oxidation catalyst (DOC) was 43 g ft ^-3 (1519 g/m ³ ).

Example 2

The catalyst was made in the same manner as in Example 1, except that the sulfur trap coating containing alpha alumina was not applied to the substrate.

Experimental results

The catalysts of Examples 1 and 2 were installed on a 6.0 liter diesel engine placed on a stand. The catalytic activity was determined by increasing the engine load in a stepwise manner to increase the temperature of the exhaust gases. The concentrations of pollutants in the exhaust gases were measured both before and after the catalyst. The oxidation activity for NO is defined as the percentage of NO ₂ as a proportion of total NO _x after the catalyst at certain temperatures of 250, 280, 310, 410 and 520°C. The percentages of NO ₂ /NO _x for Examples 1 and 2 are presented in Table 1.

Table 1

NO ₂ /NO _x after Diesel Oxidation Catalyst (DOC) (%) Diesel Oxidation Catalyst (DOC) Temperature (°C) Example 1 Example 2 250 32 thirty 280 47 47 310 57 60 410 42 44 520 fifteen fifteen

Table 1 shows the NO oxidation activity for Examples 1 and 2, expressed as the percentage of NO ₂ relative to the total amount of NO _x . Examples 1 and 2 have very similar performance. Example 1 has a sulfur trap coating made in accordance with the present invention. The addition of a sulfur trap coating does not adversely affect the NO oxidation activity.

Examples 1 and 2 were installed on a 6.0 liter diesel engine placed on a stand. The sulfur resistance of the catalysts was determined by running the engine on diesel fuel with 290 ^ppm S and exposing the catalysts to exhaust gases at 250° C. for 1 hour at a gas space velocity of 71,000. After this exposure to sulfur, the temperature of the diesel oxidation catalyst (DOC ) was increased to 350°C for 20 minutes. During this time, the percentage of NO ₂ was measured as a proportion of the total NO _x after the diesel oxidation catalyst (DOC). This procedure was repeated 49 times. The results are shown in FIG. 12.

Fig. 12 shows NO oxidation activity expressed as percentage of NO ₂ as a proportion of NO _x for Examples 1 and 2 over 49 cycles of exposure to sulfur. Example 1 maintains a higher NO oxidation activity over 49 cycles than Example 2. Example 1 contains a sulfur trapping coating made in accordance with the present invention. Example 2 does not contain a sulfur trapping coating and exhibits greater degradation in NO oxidation parameters over 49 cycles of sulfur exposure.

For the avoidance of any doubt, the entire contents of any and all documents cited in this document are incorporated by reference in this document.

Claims (17)

1. An exhaust system for treating exhaust gases produced by a diesel engine, wherein the exhaust system comprises an oxidation catalyst and a downstream emission control device which is a selective catalytic reduction catalyst or a selective catalytic reduction filter catalyst, the catalyst oxidation does not contain rhodium and contains: flowing monolithic base; a catalytic zone located at the inlet end of the base, and the catalytic zone has a length of from 10 to 90% of the length of the base; where the catalytic zone contains a catalytic material containing a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd) and a combination of platinum (Pt) and palladium (Pd); and a capture zone located at the outlet end of the base and having a length of from 15 to 65% of the length of the base, and the capture zone contains a capture material for capturing at least one sulfur-containing impurity in the exhaust gases generated by a diesel engine, and this capture material contains a metal for reaction reaction with sulfur oxide in exhaust gases and refractory oxide particles, where the metal for reaction with sulfur oxide in exhaust gases is palladium (Pd), and where the refractory oxide particles have an average specific surface area ≤50 m ² /g, determined by physical adsorption nitrogen at -196°C using the volumetric method and using the BET isothermal adsorption equation, wherein the catalytic zone is adjacent to the capture zone or where the capture zone is both adjacent to the catalytic zone and covers the catalytic zone. 2. The exhaust system of claim 1, wherein the capture material comprises metal particles for reaction with sulfur oxide in the exhaust gases having an average particle size of ≥10 nm as determined by CO chemisorption. 3. An exhaust system according to claim 1 or 2, wherein the refractory oxide is alumina. 4. An exhaust system according to any one of the preceding claims, wherein the platinum group metal (PGM) in the catalytic zone is platinum (Pt). 5. The exhaust system according to any one of paragraphs. 1-3, in which the platinum group metal (PGM) in the catalytic zone is palladium (Pd). 6. The exhaust system according to any one of paragraphs. 1-3, in which the platinum group metal (PGM) in the catalytic zone is a combination of platinum (Pt) and palladium (Pd). 7. An exhaust system according to any one of the preceding claims, wherein the catalytic material further comprises a carrier material, and wherein a platinum group metal (PGM) is supported on the carrier material. 8. The exhaust system according to claim 7, in which the carrier material contains a refractory oxide selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide, cerium oxide, silicon dioxide-aluminum oxide, titanium dioxide - alumina, zirconia-alumina, cerium-alumina, titania-silica, zirconia-silicon dioxide, zirconia-titanium dioxide, cerium-zirconia and alumina-magnesium oxide. 9. The exhaust system of claim 8, wherein the refractory metal oxide is alumina, silica, or silica-alumina. 10. The exhaust system of claim 8, wherein the refractory metal oxide is titanium dioxide. 11. An exhaust system according to any one of the preceding claims, wherein the base has a diameter of ≥7 inches (17.8 cm). 12. Heavy duty diesel vehicle comprising an exhaust system according to any one of the preceding claims.

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