NOX ADSORBER DIESEL OXIDATION CATALYST

Abstract

The present invention relates to a NOx adsorber diesel oxidation catalyst (NA-DOC) for the treatment of an exhaust gas, the catalyst comprising: a substrate comprising an inlet end, an outlet end, a substrate axial length extending from the inlet end to the outlet end and a plurality of passages defined by internal walls of the substrate extending therethrough; a NOx adsorber (NA) coating disposed on the surface of the internal walls of the substrate, said coating comprising a platinum group metal, a zeolitic material and one or more of an alkaline earth metal and manganese; and a diesel oxidation catalyst (DOC) coating, said coating comprising a platinum group metal supported on a non-zeolitic oxidic material.

Claims

1. A NOx adsorber diesel oxidation catalyst (NA-DOC) for the treatment of an exhaust gas, the catalyst comprising: (i) a substrate comprising an inlet end, an outlet end, a substrate axial length extending from the inlet end to the outlet end and a plurality of passages defined by internal walls of the substrate extending therethrough; (ii) a NOx adsorber (NA) coating disposed on the surface of the internal walls of the substrate (i), said coating comprising a platinum group metal, a zeolitic material and one or more of an alkaline earth metal and manganese; (iii) a diesel oxidation catalyst (DOC) coating, said coating comprising a platinum group metal supported on a non-zeolitic oxidic material.

2. The catalyst of claim 1, wherein the platinum group metal comprised in the NA coating (ii) is selected from the group consisting of palladium, platinum, rhodium, iridium, osmium, ru-thenium and a mixture of two or more thereof, preferably selected from the group consist-ing of palladium, platinum and rhodium, more preferably selected from the group consist-ing of palladium and platinum.

3. The catalyst of claim 1, wherein the zeolitic material comprised in the NA coating (ii) is a 10-membered ring pore zeolitic material, wherein the 10-membered ring pore zeolitic material preferably has framework type selected from the group consisting of FER, TON, MTT, SZR, MFI, MWW, AEL, HEU, AFO, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of FER, TON, MFI, MWW, AEL, HEU, AFO, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of FER and TON, wherein more preferably the 10-membered ring pore zeolitic material comprised in the NA coating (ii) has a framework type FER.

4. The catalyst of claim 2, wherein platinum group metal comprised in the NA coating (ii) is palladium and wherein the zeolitic material comprised in the NA coating (ii) is a 10-membered ring pore zeolitic material having a framework type FER or TON, preferably FER.

5. The catalyst of claim 1, wherein the NA coating (ii) comprises an alkaline earth metal, wherein the alkaline earth metal is preferably selected from the group consisting of barium, strontium, calcium, magnesium and a mixture of two or more thereof, more preferably selected from the group consisting of barium, strontium, magnesium and a mix-ture of two or more thereof, more preferably is barium, strontium and a mixture of two or more thereof, more preferably is barium or strontium or barium and strontium; wherein the NA coating (ii) preferably comprises the alkaline earth metal in a total amount, calculated as the oxide, in the range of from 0.5 to 15 weight-%, more preferably in the range of from 1 to 10 weight-%, more preferably in the range of from 1.5 to 8 weight-%, based on the weight of the zeolitic material comprised in the NA coating (ii).

6. The catalyst of claim 1, wherein the NA coating (ii) comprises manga-nese, wherein the NA coating (ii) preferably comprises manganese in an amount calculat-ed as MnO.sub.2, in the range of from 0.25 to 5 weight-%, more preferably in the range of from 0.5 to 3 weight-%, more preferably in the range of from 0.75 to 1.5 weight-% based on the weight of the zeolitic material comprised in the NA coating (ii).

7. The catalyst of claim 5, wherein the NA coating (ii) comprises barium and manga-nese; or strontium and manganese; or barium, strontium and manganese.

8. The catalyst of claim 6, wherein the NA coating (ii) further comprises an alkali metal, wherein the alkali metal is preferably selected from the group consisting of sodium, potas-sium and lithium, wherein the alkali metal is preferably sodium.

9. The catalyst of claim 1, wherein the platinum group metal comprised in the DOC coating (iii) is selected from the group consisting of palladium, platinum, rhodi-um, iridium, osmium and ruthenium and a mixture of two or more thereof, preferably se-lected from the group consisting of palladium, platinum and rhodium, more preferably se-lected from the group consisting of palladium and platinum, more preferably is platinum.

10. The catalyst of claim 1, wherein the NA coating disposed on the surface of the internal walls of the substrate (i) extends over x % of the substrate axial length, preferably from the outlet end towards the inlet end, with x being in the range of from 40 to 100 and wherein the DOC coating extends over y % of the substrate axial length, prefera-bly from the inlet end towards the outlet end, with y being in the range of from 20 to 100.

11. The catalyst of claim 1, wherein the DOC coating (iii) has a single coat.

12. The catalyst of claim 1, wherein the DOC coating (iii) comprises, prefer-ably consists of, (iii.1) an inlet coat comprising the platinum group metal, preferably platinum, the non-zeolitic oxidic material and a zeolitic material; and (iii.2) an outlet coat comprising the platinum group metal, preferably platinum, and the non-zeolitic oxidic material; wherein the inlet coat (iii.1) extends over y1% of the substrate axial length from the inlet end towards the outlet end of the substrate according to (i), wherein y1 is in the range of from 20 to 80, preferably in the range of from 30 to 60, more preferably in the range of from 45 to 55, and wherein the outlet coat (iii.2) extends over y2% of the substrate axial length from the out-let end towards the inlet end of the substrate according to (i), wherein y2 is in the range of from 20 to 80, preferably in the range of from 30 to 60, more preferably in the range of from 45 to 55.

13. The catalyst of claim 1, wherein the DOC coating is disposed on the NA coating; preferably, wherein the DOC coating extends over y % of the substrate axial length, with y being in the range of from 98 to 100 and the NA coating extends over x % of the substrate axial length, more preferably from the outlet end towards the inlet end of the substrate, with x being in the range of from 98 to 100.

14. Process for preparing a NOx adsorber diesel oxidation catalyst (NA-DOC), preferably the NOx adsorber diesel oxidation catalyst (NA-DOC) according to claim 1, comprising (a) preparing a first mixture comprising water, a source of a platinum group metal, a ze-olitic material and a source of one or more of an alkaline earth metal and manganese; (b) disposing the first mixture obtained according to (a) on the surface of the internal walls of a substrate comprising an inlet end, an outlet end, a substrate axial length extending from the inlet end to the outlet end and a plurality of passages defined by internal walls of the substrate extending therethrough; calcining, obtaining a sub-strate having a NA coating thereon; (c) preparing a second mixture comprising water, a source of a platinum group metal and a non-zeolitic oxidic material; (d) disposing the second mixture obtained according to (c) on the substrate having a NA coating thereon; (e) calcining the substrate obtained according to (d), obtaining a substrate having a NA coating and a DOC coating thereon.

15. A NOx adsorber diesel oxidation catalyst (NA-DOC) obtained or obtainable by a process according to claim 14.

16. Use of a NOx adsorber diesel oxidation catalyst (NA-DOC) according to claim 1 for the NOx adsorption/desorption and the conversion of HC and CO.

17. An exhaust treatment system for the treatment of an exhaust gas, the system comprising a NOx adsorber diesel oxidation (NA-DOC) catalyst according to claim 1; the system further comprises one or more of a selective catalytic reduction catalyst (SCR), a selective catalytic reduction catalyst on a filter (SCRoF) and an ammonia oxidation (AMOX) catalyst, wherein the NA-DOC catalyst is preferably located upstream of the one or more of a selective catalytic reduction catalyst (SCR), a selective catalytic reduction catalyst on a filter (SCRoF) and an ammonia oxidation (AMOX) catalyst.

Description

EXAMPLES

Reference Example 1

1.1 Determination of the Particle Size Distribution, Dv10, Dv50, Dv90 Values

[0278] The particle size distributions were determined by a static light scattering method using Sympatec HELOS equipment, wherein the optical concentration of the sample was in the range of from 5 to 10%.

1.2 Measurement of the BET Specific Surface Area

[0279] The BET specific surface area was determined according to DIN 66131 or DIN ISO 9277 using liquid nitrogen.

1.3 Determination of the Crystallinity

[0280] The determination of the relative crystallinity of a zeolite was performed via x-ray diffraction using a test method under the jurisdiction of ASTM Committee D32 on catalysts, in particular of Subcommittee D32.05 on zeolites. The current edition was approved on Mar. 10, 2001 and published in May 2001, which was originally published as D 5758-95.

1.4 Determination of the Total Pore Volume

[0281] The total pore volume was determined according to ISO 15901-2:2006.

Comparative Example 1: Preparation of a NOx Adsorber Diesel Oxidation CatalystFER

Bottom Coating (NA Coating):

[0282] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution to attain a Pd loading of 0.8 weight-% based on the weight of the final material (zeolitic material+palladium). To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0283] A porous uncoated flow-through honeycomb substrate, cordierite (total volume 0.04 L, 400 cpsi and 4 mil wall thickness, diameter: 1 inch x length: 3 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 20 g/ft.sup.3 and the concentration of the FER in bottom coating loading was 1.5 g/in.sup.3. The loading of the bottom coating was 1.51 g/in.sup.3.

Top Coating (DOC Coating):

[0284] An alumina support material comprising 5% by weight SiO.sub.2 was impregnated with platinum via a wet impregnation process. A Fe-Beta zeolitic material (a zeolitic material having framework structure type BEA, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 23:1 and a crystallinity vs. standard (XRD) >90% and Fe content, calculated as Fe.sub.2O.sub.3: 4.3 weight-% based on the weight of the zeolitic material) was added to the Pt-alumina slurry. The weight ratio of the alumina doped with Si to the Beta zeolitic material was of 4.2/1. A slurry containing this material and Beta zeolite was coated over 100% of the cordierite substrate containing already the Pd/FER bottom layer. The coated substrate was dried in air at 120? C. for 60 min and calcined in air at 590? C. ? C. for 2 hours. The top layer contained 60 g/ft.sup.3 platinum. The loading of the top coating was 1.9 g/in.sup.3.

Examples 1 to 3: Preparation of a NOx-Adsorber Diesel Oxidation CatalystFER with Ba Additive

Bottom Coating (NA Coating):

[0285] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution and barium hydroxide to attain a Pd loading of 0.77 weight-% based on the weight of the final material (zeolitic material+palladium) and the following weight-% based Ba loadings:

TABLE-US-00001 Ba content, calculated as Sample BaO, in weight-% (bottom coating) based on the FER amount Example 1 1.7 Example 2 3.4 Example 3 6.8

[0286] To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0287] A porous uncoated flow-through honeycomb substrate, cordierite (total volume 0.04 L, 400 cpsi and 4 mil wall thickness, core with diameter: 1 inch x length: 3 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air having a temperature of 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 20 g/ft.sup.3 and the concentration of the FER in bottom coating loading was 1.5 g/in.sup.3. The loading of the bottom coating was 1.61 g/in.sup.3 (Ex. 1), 1.64 g/in.sup.3 (Ex. 2) and 1.69 g/in.sup.3 (Ex. 3).

Top Coating (DOC Coating):

[0288] The slurries for preparing the top coating of Examples 1-3 were prepared as the slurry for preparing the top coating of Comparative Example 1. The slurry for each of Examples 1-3 was coated over 100% of the cordierite substrate containing already the Ba/Pd/FER bottom coating. The top coating contained 60 g/ft.sup.3 platinum. The loading of the top coating was 1.9 g/in.sup.3.

Examples 4 to 6: Preparation of a NOx-Adsorber Diesel Oxidation CatalystFER with Sr Additive

Bottom Coating (NA Coating):

[0289] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution and strontium acetate to attain a Pd loading of 0.77 weight-% based on the weight of the final material (zeolitic material+palladium) an the following Sr content:

TABLE-US-00002 Sr content, calculated as Sample SrO, in weight.% (bottom coating) based on the FER amount Example 4 1.7 Example 5 3.4 Example 6 6.8

[0290] To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0291] A porous uncoated flow-through honeycomb substrate, cordierite (total volume 0.04 L, 400 cpsi and 4 mil wall thickness, diameter: 1 inch x length: 3 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air having a temperature of 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 20 g/ft.sup.3 and the concentration of the FER in bottom coating loading was 1.5 g/in.sup.3. The loading of the bottom coating was 1.61 g/in.sup.3 (Ex. 4), 1.64 g/in.sup.3 (Ex. 5) and 1.69 g/in.sup.3 (Ex. 6).

Top Coating (DOC Coating):

[0292] The slurries for preparing the top coating of Examples 4-6 were prepared as the slurry for preparing the top coating of Comparative Example 1. The slurry for each of Examples 1-3 was coated over 100% of the cordierite substrate containing already the Sr/Pd/FER bottom coating. The top coating contained 60 g/ft.sup.3 platinum. The loading of the top coating was 1.9 g/in.sup.3.

TABLE-US-00003 TABLE 1 Bottom coating Top coating Sample (substrate axial length) (substrate axial length) Comp. 20 g/ft.sup.3 Pd-FER (100%) 60 g/ft.sup.3 Pt Alumina + Example 1 Fe-Beta (100%) Example 1 20 g/ft.sup.3 Pd-FER + 60 g/ft.sup.3 Pt Alumina + 1.7 wt.-% BaO (100%) Fe-Beta (100%) Example 2 20 g/ft.sup.3 Pd-FER + 60 g/ft.sup.3 Pt Alumina + 3.4 wt.-% BaO (100%) Fe-Beta (100%) Example 3 20 g/ft.sup.3 Pd-FER + 60 g/ft.sup.3 Pt Alumina + 6.8 wt.-% BaO (100%) Fe-Beta (100%) Example 4 20 g/ft.sup.3 Pd-FER + 60 g/ft.sup.3 Pt Alumina + 1.7 wt.-% SrO (100%) Fe-Beta (100%) Example 5 20 g/ft.sup.3 Pd-FER + 60 g/ft.sup.3 Pt Alumina + 3.4 wt.-% SrO (100%) Fe-Beta (100%) Example 6 20 g/ft.sup.3 Pd-FER + 60 g/ft.sup.3 Pt Alumina + 6.8 wt.-% SrO (100%) Fe-Beta (100%)

Example 7: Evaluation of NOx-Adsorber Diesel Oxidation Catalyst of Comparative Example 1 and of Examples 2 to 6 on a Lab Reactor

[0293] The catalysts of Examples 2 to 6 and of Comparative Example 1 were tested for NOx adsorption and desorption performance after hydrothermal aging at 800? C. for 16 hours in 10% steam (water)/air. Prior to desorption, the cores were exposed to a mixture of 200 ppm nitric oxide (NO), 500 ppm carbon monoxide (CO), 500 ppm propylene (C.sub.3H.sub.6, C.sub.1 basis), 7% oxygen (O.sub.2), 5% carbon dioxide (CO.sub.2), 5% water (H.sub.2O) and balance nitrogen (N.sub.2) for 15 minutes at 100? C. During this period, NO was adsorbed to the Pd/FER. After the adsorption phase, the NO, CO and propylene were turned off and the temperature of the sample was raised to 500? C. at 60K/min. During this period, NO that was adsorbed to the Pd/FER was desorbed (desorption phase). The temperature of the NOx adsorption and the amount of desorbed NOx was evaluated. NO desorption curves for the Comparative Example 1 and Examples 2-6 as a function of temperature are shown in FIG. 1. The amount of desorbed NOx is shown in Table 1.

TABLE-US-00004 TABLE 2 Amount of desorbed NOx for Comparative Example 1 and Examples 2-6 Sample Desorbed amount of NOx/g/l Comp. Example 1 0.20 Example 1 0.21 Example 2 0.20 Example 3 0.18 Example 4 0.18 Example 5 0.17 Example 6 0.16

[0294] As may be taken from FIG. 1, namely the NOx desorption curves of the tested samples, it can be concluded that the additive Sr and Ba permit the desired increase of the NOx desorption temperature. Indeed, such additives permit to reduce the first peak desorption temperature (about 200? C.) and increase the second peak desorption temperature (about 300? C.). The higher the amount of the additive the higher the increase of the NOx desorption. It is noted that the increase of the additive can also result in a slight decrease in the adsorption capacity which can be seen in Table 1 but in any case the adsorption capacity obtained by the catalysts according to the present invention are good. The amount of desorbed NOx relates to the previously adsorbed NOx at 100? C.

Comparative Example 2: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystFER

Bottom Coating (NA Coating):

[0295] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution to attain a Pd loading of 1.48 weight-% based on the weight of the final material (zeolitic material+palladium). To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0296] A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 1.85 L, 400 cpsi and 4 mil wall thickness, diameter: 5.66 inches?length: 4.5 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.7 g/in.sup.3 and of ZrO.sub.2 was 0.135 g/in.sup.3. The loading of the bottom coating was 2.9 g/in.sup.3.

Top Coating (DOC Coating):

Outlet Coat:

[0297] An Al.sub.2O.sub.3 support material comprising 5 weight-% MnO.sub.2 (Al.sub.2O.sub.3 95 weight-% with Mn 5 weight-%, calculated as MnO.sub.2, having a BET specific surface area of greater than 100 m.sup.2/g, and a pore volume of greater than 0.06 cm.sup.3/g) was impregnated with platinum via a wet impregnation process. A slurry containing the resulting material was coated over 50% of the substrate axial length from the outlet end towards the inlet end of the cordierite substrate carrying the Pd-FER bottom coating. The outlet coat contained 80 g/ft.sup.3 platinum and the loading of the outlet coat was 1.3 g/in.sup.3.

Inlet Coat:

[0298] An alumina support material comprising 5% by weight SiO.sub.2 was impregnated with platinum and palladium in a weight ratio of 2:1 via a wet impregnation process. A Fe-Beta zeolitic material (a zeolitic material having framework structure type BEA, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 23:1 and a crystallinity vs. standard (XRD) >90% and Fe content, calculated as Fe.sub.2O.sub.3: 4.3 weight-% based on the weight of the zeolitic material) was added to the Pt/Pd-alumina slurry. The weight ratio of the alumina doped with Si to the Beta zeolitic material was of 1/1. A slurry containing this material and Beta zeolite was coated over 50% of the substrate axial length from the inlet end towards the outlet end of the cordierite substrate supporting already the Pd-FER bottom layer and the outlet coat. The inlet coat contained 13.3 g/ft.sup.3 platinum and 6.7 g/ft.sup.3 Pd. The loading of the inlet coat was 1.41 g/in.sup.3. The total loading of the top coating (outlet coat+inlet coat) was 1.355 g/in.sup.3.

Example 8A: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystFER with Mn Additive

Bottom Coating (NA Coating):

[0299] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution and Manganese nitrate to attain a Pd loading of 1.48 weight-% based on the weight of the zeolitic material+palladium and 1 weight-% MnO.sub.2 loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0300] A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 1.85 L, 400 cpsi and 4 mil wall thickness, diameter: 5.66 inches?length: 4.5 inches), was coated with the obtained slurry over 100% of its substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 70 g/ft.sup.3 and the concentration of the FER in bottom coating loading was 2.7 g/in.sup.3 and of ZrO.sub.2 was 0.135 g/in.sup.3. The loading of the bottom coating was about 2.927 g/in.sup.3.

Top Coating (DOC Coating):

[0301] The top coating of Example 8A was prepared as the top coating of Comparative Example 2 and covers the bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.355 g/in.sup.3.

Example 8: Preparation of High Pd Containing a NOx-Adsorber Diesel Oxidation CatalystFER with Ba Additive

Bottom Coating (NA Coating):

[0302] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution and barium hydroxide to attain a Pd loading of 1.48 weight-% based on the weight of the final material (zeolitic material+palladium) and 6.8 weight-% BaO loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0303] A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 1.85 L, 400 cpsi and 4 mil wall thickness, diameter: 5.66 inches?length: 4.5 inches), was coated with the obtained slurry over 100% of its substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.7 g/in.sup.3 and of ZrO.sub.2 was 0.135 g/in.sup.3. The loading of the bottom coating was about 3.084 g/in.sup.3.

Top Coating (DOC Coating):

[0304] The top coating of Example 8 was prepared as the top coating of Comparative Example 2 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.355 g/in.sup.3.

Example 9: Preparation of High Pd Containing a NOx-Adsorber Diesel Oxidation CatalystFER with Sr Additive

Bottom Coating (NA Coating):

[0305] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution and strontium acetate to attain a Pd loading of 1.48 weight-% based on the weight of the final material zeolitic material+palladium) and 6.8 weight-% SrO loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0306] A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 1.85 L, 400 cpsi and 4 mil wall thickness, diameter: 5.66 inches?length: 4.5 inches), was coated with the obtained slurry over 100% of its substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.7 g/in.sup.3 and of ZrO.sub.2 was 0.135 g/in.sup.3. The loading of the bottom coating was about 2.9 g/in.sup.3.

Top Coating DOC (Second Coating):

[0307] The top coating of Example 9 was prepared as the top coating of Comparative Example 2 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.355 g/in.sup.3.

Example 10: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystFER with Mn and Ba Additives

Bottom Coating (NA Coating):

[0308] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution, Barium hydroxide and Manganese nitrate to attain a Pd loading of 1.48 weight-% based on the weight of the final material (zeolitic material+palladium), 4.3 weight-% BaO and 1 weight-% MnO.sub.2 loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0309] A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 1.85 L, 400 cpsi and 4 mil wall thickness, diameter: 5.66 inches?length: 4.5 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.7 g/in.sup.3 and of ZrO.sub.2 was 0.135 g/in.sup.3. The loading of the bottom coating was 3.11 g/in.sup.3.

Top Coating (DOC Coating):

[0310] The top coating of Example 8 was prepared as the top coating of Comparative Example 2 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.355 g/in.sup.3.

TABLE-US-00005 TABLE 3 Bottom coating Top coating Samples (substrate axial length) (substrate axial length) Comp. 70 g/ft.sup.3 Pd-FER (100%) Inlet (50%): 20 g/ft.sup.3 Example 2 Pt/Pd-Alumina + Fe-Beta Outlet (50%): 80 g/ft.sup.3 Pt-Alumina Example 8A 70 g/ft.sup.3 Pd-FER + Inlet (50%): 20 g/ft.sup.3 1% MnO.sub.2 (100%) Pt/Pd-Alumina + Fe-Beta Outlet (50%): 80 g/ft.sup.3 Pt-Alumina Example 8 70 g/ft.sup.3 Pd-FER + Inlet (50%): 20 g/ft.sup.3 6.8 wt.-% BaO (100%) Pt/Pd-Alumina + Fe-Beta Outlet (50%): 80 g/ft.sup.3 Pt Alumina Example 9 20 g/ft.sup.3 Pd-FER + Inlet (50%): 20 g/ft.sup.3 6.8 wt.-% SrO (100%) Pt/Pd-Alumina + Fe-Beta Outlet (50%): 80 g/ft.sup.3 Pt-Alumina Example 10 70 g/ft.sup.3 Pd-FER + Inlet (50%): 20 g/ft.sup.3 1 wt.-% MnO.sub.2 + Pt/Pd-Alumina + Fe-Beta 4.3 wt.-% BaO (100%) Outlet (50%): 80 g/ft.sup.3 Pt-Alumina

Example 11: Evaluation of NOx Adsorber Diesel Oxidation Catalyst Comparative Example 2 and Examples 8A, 8 to 10 on a Lab Reactor

[0311] Cores having a diameter of 1 inch and a length of 3 inches were drilled out from the coated substrates of Comparative Example 2, Examples 8A and 8-10 to be tested on a Lab reactor. These cores were tested for NOx adsorption and desorption performance after hydrothermal aging at 800? C. for 16 hours in 10% steam (water)/air. Prior to desorption, the cores were exposed to a mixture of 200 ppm nitric oxide (NO), 500 ppm carbon monoxide (CO), 500 ppm propylene (C.sub.3H.sub.6, C.sub.1 basis), 7% oxygen (O.sub.2), 5% carbon dioxide (CO.sub.2), 5% water (H.sub.2O) and balance nitrogen (N.sub.2) for 15 minutes at 100? C. During this period, NO was adsorbed to the Pd/FER. After the adsorption phase, the NO, CO and propylene were turned off and the temperature of the sample was raised to 500? C. at 20? C./min. During this period, NO that was adsorbed to the Pd/zeolite was desorbed (desorption phase). The temperature of NOx adsorption and the amount of desorbed NOx was evaluated. NO desorption curves for Comparative Example 2, Reference Example 2 and Examples 8-10 as a function of temperature are shown in FIG. 2. The amount of desorbed NOx is shown in Table 4. The amount of desorbed NOx relates to the previously adsorbed NOx at 100? C.

TABLE-US-00006 TABLE 4 Amount of desorbed NOx for Comparative Example 2, Examples 8A and 8-10 Sample Desorbed amount of NOx/g/l Comp. Example 2 0.56 Example 8A 0.61 Example 8 0.55 Example 9 0.34 Example10 0.52
As may be taken from FIG. 2, namely the NOx desorption curves, it can be concluded that the additive Mn, Sr and Ba as well as Ba+Mn cause the desired increase of the NOx desorption temperature also with high Pd loading. The optimum NOx desorption window is achieved for the Example 10, the combination of the additives Ba and Mn. The adsorption capacity is only slightly reduced for Example 10.

Example 12: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystFER with Mn and Na Additives

Bottom Coating (NA Coating):

[0312] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution, sodium nitrate and manganese nitrate to attain a Pd loading of 1.59 weight-% based on the weight of the final material (zeolitic material+palladium), 0.7 weight-% NaO and 1 weight-% MnO.sub.2 loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material.

[0313] A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 0.04 L, 400 cpsi and 4 mil wall thickness, core of diameter: 1 inch x length: 3 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.5 g/in.sup.3 and of ZrO.sub.2 was 0.125 g/in.sup.3. The loading of the bottom coating was 2.71 g/in.sup.3.

Top Coating (DOC Coating):

[0314] The top coating of Example 12 was prepared as the top coating of Example 1-3 and covers the aforementioned bottom coating over 100% of the substrate axial length, except that the platinum loading was of 50 g/ft.sup.3. The total loading of the top coating was 1.9 g/in.sup.3.

Example 13: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystFER with Mn and Sr Additives

Bottom Coating (NA Coating):

[0315] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution, strontium acetate and manganese nitrate to attain a Pd loading of 1.59 weight-% based on the weight of the final material (zeolitic material+palladium), 3 weight-% SrO and 1 weight-% MnO.sub.2 loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material. A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 0.04 L, 400 cpsi and 4 mil wall thickness, core of diameter: 1 inch x length: 3 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.5 g/in.sup.3 and of ZrO.sub.2 was 0.125 g/in.sup.3. The loading of the bottom coating was 2.76 g/in.sup.3.

Top Coating (DOC Coating):

[0316] The top coating of Example 13 was prepared as the top coating of Example 12 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.9 g/in.sup.3.

Example 14: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystFER with Mn and Ba Additives

Bottom Coating (NA Coating):

[0317] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution, barium hydroxide and manganese nitrate to attain a Pd loading of 1.59 weight-% based on the weight of the final material (zeolitic material+palladium), 4.3 weight-% BaO and 1 weight-% MnO.sub.2 loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 20 weight-% based on the weight of the zeolitic material. A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 0.04 L, 400 cpsi and 4 mil wall thickness, core of diameter: 1 inch x length: 3 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.2 g/in.sup.3 and of ZrO.sub.2 was 0.44 g/in.sup.3. The loading of the bottom coating was 2.64 g/in.sup.3.

Top Coating (DOC Coating):

[0318] The top coating of Example 14 was prepared as the top coating of Example 12 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.9 g/in.sup.3.

TABLE-US-00007 TABLE 5 Bottom coating Top coating Sample (substrate axial length) (substrate axial length) Comp. 70 g/ft.sup.3 Pd-FER + Inlet (50%): 20 g/ft.sup.3 Example 2 5 wt.-% ZrO.sub.2 (100%) Pt/Pd-Alumina + Fe-Beta Outlet (50%): 80 g/ft.sup.3 Pt-Alumina Example 12 70 g/ft.sup.3 Pd-FER + 50 g/ft.sup.3 Pt Alumina + 5 wt.-% ZrO.sub.2 + Fe-Beta (100%) 0.7 wt.-% NaO + 1 wt.-% MnO.sub.2 (100%) Example 13 70 g/ft.sup.3 Pd-FER + 50 g/ft.sup.3 Pt Alumina + 5 wt.-% ZrO.sub.2 + Fe-Beta (100%) 3 wt.-% SrO + 1 wt.-% MnO.sub.2 (100%) Example 14 70 g/ft.sup.3 Pd-FER + 50 g/ft.sup.3 Pt Alumina + 20 wt.-% ZrO.sub.2 + Fe-Beta (100%) 4.3 wt.-% BaO + 1 wt.-% MnO.sub.2 (100%)

Example 15: Evaluation of NOx Adsorber Diesel Oxidation Catalyst of Comparative Example 2 and Examples 8A and 12-14 on a Lab Reactor

[0319] Comparative Example 2 and Examples 8A and 12-14 were tested for NOx adsorption and desorption performance after hydrothermal aging at 800? C. for 16 hours in 10% steam (water)/air. Prior to desorption, the cores were exposed to a mixture of 200 ppm nitric oxide (NO), 500 ppm carbon monoxide (CO), 500 ppm propylene (C.sub.3H.sub.6, C.sub.1 basis), 7% oxygen (O.sub.2), 5% carbon dioxide (CO.sub.2), 5% water (H.sub.2O) and balance nitrogen (N.sub.2) for 15 minutes at 100? C. During this period, NO was adsorbed to the Pd/FER. After the adsorption phase, the NO, CO and propylene were turned off and the temperature of the sample was raised to 500? C. at 20? C./min. During this period, NO that was adsorbed to the Pd/zeolite was desorbed (desorption phase). The temperature of NOx adsorption and the amount of desorbed NOx was evaluated. NO desorption curves for Comparative Example 2 and Examples 8A and 12-14 as a function of temperature are shown in FIG. 3. The amount of desorbed NOx is shown in Table 6. The amount of desorbed NOx relates to the previously adsorbed NOx at 100? C.

TABLE-US-00008 TABLE 6 Amount of desorbed NOx for Comparative Example 2 and Examples 8A and 12-14 Sample Desorbed amount of NOx/g/l Comp. Example 2 0.56 Example 12 0.56 Example 13 0.54 Example 14 0.51

[0320] As may be taken from FIG. 3, namely the NOx desorption curves, it can be concluded that the additive Mn, Ba+Mn, Na+Mn and Sr+Mn permit the desired increase of the NOx desorption temperature also with high Pd loading. The optimum NOx desorption windows are obtained with the catalysts according to the present invention.

Comparative Example 3: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystCHA with Mn and Ba Additives

Bottom Coating (NA Coating):

[0321] The bottom coating of Comparative Example 3 was prepared as the bottom coating of Example 14 except that an ammonium CHA zeolitic material (a zeolitic material having framework structure type CHA, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 14:1 and a crystallinity vs. standard (XRD)=81%) is used to replace the ammonium ferrierite zeolitic material from Example 14. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the CHA in the bottom coating loading was 2.2 g/in.sup.3 and of ZrO.sub.2 was 0.44 g/in.sup.3. The loading of the bottom coating was 2.64 g/in.sup.3.

Top Coating (DOC Coating):

[0322] The top coating of Comparative Example 3 was prepared as the top coating of Example 14 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.9 g/in.sup.3.

Comparative Example 4: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystBEA with Mn and Ba Additives

Bottom Coating (NA Coating):

[0323] The bottom coating of Comparative Example 4 was prepared as the bottom coating of Example 14 except that an ammonium BEA zeolitic material (a zeolitic material having framework structure type BEA, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 14:1 and a crystallinity vs. standard (XRD) >80%) is used to replace the ammonium ferrierite zeolitic material from Example 14. The concentration of palladium in the bottom coating was 70 g/ft.sup.3, the concentration of the BEA in the bottom coating loading was 2.2 g/in.sup.3 and of ZrO.sub.2 was 0.44 g/in.sup.3. The loading of the bottom coating was 2.64 g/in.sup.3.

Top Coating (DOC Coating):

[0324] The top coating of Comparative Example 3 was prepared as the top coating of Example 14 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.9 g/in.sup.3.

TABLE-US-00009 TABLE 7 Bottom coating Top coating Sample (substrate axial length) (substrate axial length) Comparative 70 g/ft.sup.3 Pd-CHA + 50 g/ft.sup.3 Pt Alumina + Example 3 20 wt.-% ZrO.sub.2 + Fe-Beta (100%) 4.3 wt.-% BaO + 1 wt.-% MnO.sub.2 (100%) Comparative 70 g/ft.sup.3 Pd-BEA + 50 g/ft.sup.3 Pt Alumina + Example 4 20 wt.-% ZrO.sub.2 + Fe-Beta (100%) 4.3 wt.-% BaO + 1 wt.-% MnO.sub.2 (100%) Example 14 70 g/ft.sup.3 Pd-FER + 50 g/ft.sup.3 Pt Alumina + 20 wt.-% ZrO.sub.2 + Fe-Beta (100%) 4.3 wt.-% BaO + 1 wt.-% MnO.sub.2 (100%)

Example 16: Evaluation of NOx Adsorber Diesel Oxidation Catalyst of Comparative Examples 3 and 4 and Example 14

[0325] Comparative Examples 3 and 4 and Example 14 were tested for NOx adsorption and desorption performance after hydrothermal aging at 800? C. for 16 hours in 10% steam (water)/air. Prior to desorption, the cores were exposed to a mixture of 200 ppm nitric oxide (NO), 500 ppm carbon monoxide (CO), 500 ppm propylene (C.sub.3H.sub.6, C.sub.1 basis), 7% oxygen (O.sub.2), 5% carbon dioxide (CO.sub.2), 5% water (H.sub.2O) and balance nitrogen (N.sub.2) for 15 minutes at 100? C. During this period, NO was adsorbed to the Pd/zeolite. After the adsorption phase, the NO, CO and propylene were turned off and the temperature of the sample was raised to 500? C. at 60 K/min. During this period, NO that was adsorbed to the Pd/zeolite was desorbed (desorption phase). The temperature of NOx adsorption and the amount of desorbed NOx was evaluated. NO desorption curves for Comparative Examples 3 and 4 and Example 14 as a function of temperature are shown in FIG. 4. The amount of desorbed NOx is shown in Table 8. The amount of desorbed NOx relates to the previously adsorbed NOx at 100? C.

TABLE-US-00010 TABLE 8 Amount of desorbed NOx for Comparative Examples 3 and 4 and Example 14 Sample Desorbed amount of NOx/g/l Comp. Example 3 0.24 Comp. Example 4 0.12 Example 14 0.51

[0326] As may be taken from FIG. 4, namely the NOx desorption curves, it can be concluded that the catalyst according to the present invention permits the desired increase of the NOx desorption temperature also with high Pd loading compared to the catalysts representative of the prior art, namely the catalysts of Comparative Examples 3 and 4. The optimum NOx desorption windows are clearly obtained with the catalyst according to the present invention.

Example 17: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystFER with Mn and Ba Additives

Bottom Coating (NA Coating):

[0327] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution, barium hydroxide and manganese nitrate to attain a Pd loading of 1.14 weight-% based on the weight of the final material (zeolitic material+palladium), 4.3 weight-% BaO and 1 weight-% MnO.sub.2 loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material. A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 0.04 L, 400 cpsi and 4 mil wall thickness, core of diameter: 1 inch x length: 3 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 50 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.5 g/in.sup.3 and of ZrO.sub.2 was 0.125 g/in.sup.3. The loading of the bottom coating was 2.8 g/in.sup.3.

Top Coating (DOC Coating):

[0328] The top coating of Example 17 was prepared as the top coating of Example 12 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.9 g/in.sup.3.

Example 18: Preparation of High Pd Containing a NOx Adsorber Diesel Oxidation CatalystFER with Mn, Ba and Sr Additives

Bottom Coating (NA Coating):

[0329] An ammonium ferrierite zeolitic material (a zeolitic material having framework structure type FER, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21:1 and a crystallinity vs. standard (XRD) >80%) was wet impregnated with an aqueous palladium nitrate solution, barium hydroxide, strontium acetate and manganese nitrate to attain a Pd loading of 1.14 weight-% based on the weight of the final material (zeolitic material+palladium), 2 weight-% BaO, 0.5% weight-% SrO and 1 weight-% MnO.sub.2 loading based on the FER amount. To the resulting slurry a zirconium acetate mixture was added. The amount of zirconium acetate was calculated such that the amount of zirconia in the bottom coating, calculated as ZrO.sub.2, was 5 weight-% based on the weight of the zeolitic material. A porous uncoated round flow-through honeycomb substrate, cordierite (total volume 0.04 L, 400 cpsi and 4 mil wall thickness, core of diameter: 1 inch x length: 3 inches), was coated with the obtained slurry over 100% of the substrate axial length. The coated substrate was dried in air at 110? C. for 1 h and subsequently calcined in air at 590? C. for 2 h, forming a bottom coating. The concentration of palladium in the bottom coating was 50 g/ft.sup.3, the concentration of the FER in bottom coating loading was 2.5 g/in.sup.3 and of ZrO.sub.2 was 0.125 g/in.sup.3. The loading of the bottom coating was 2.75 g/in.sup.3.

Top Coating (DOC Coating):

[0330] The top coating of Example 17 was prepared as the top coating of Example 12 and covers the aforementioned bottom coating over 100% of the substrate axial length. The total loading of the top coating was 1.9 g/in.sup.3.

TABLE-US-00011 TABLE 9 Bottom coating Top coating Sample (substrate axial length) (substrate axial length) Example 17 50 g/ft.sup.3 Pd-FER + 50 g/ft.sup.3 Pt Alumina + 5 wt.-% ZrO.sub.2 + Fe-Beta (100%) 4.3 wt.-% BaO + 1 wt.-% MnO.sub.2 (100%) Example 18 50 g/ft.sup.3 Pd-FER + 50 g/ft.sup.3 Pt Alumina + 5 wt.-% ZrO.sub.2 + Fe-Beta (100%) 2 wt.-% BaO + 0.5% SrO + 1 wt.-% MnO.sub.2 (100%)

Example 19: Evaluation of NOx Adsorber Diesel Oxidation Catalyst of Examples 17 and 18 on a Lab Reactor

[0331] The catalysts of Examples 17 and 18 were tested as defined in Example 16.

TABLE-US-00012 TABLE 10 Amount of desorbed NOx for Examples 17 and 18 Sample Desorbed amount of NOx/g/l Example 17 0.34 Example 18 0.41

[0332] As may be taken from FIG. 5, namely the NOx desorption curves, it can be concluded that the additives Mn+Ba+Sr and Mn+Ba permit the desired increase of the NOx desorption temperature also with medium Pd loading.

BRIEF DESCRIPTION OF THE FIGURES

[0333] FIG. 1 shows the NOx desorption curves obtained with the catalysts of Comparative Example 1 and of Examples 1 to 6.

[0334] FIG. 2 shows the NOx desorption curves obtained with the catalysts of Comparative Example 2 and of Examples 8A and 8 to 10.

[0335] FIG. 3 shows the NOx desorption curves obtained with the catalysts of Comparative Example 2 and of Examples 12 to 14.

[0336] FIG. 4 shows the NOx desorption curves obtained with the catalysts of Comparative Examples 3 and 4 and of Example 14.

[0337] FIG. 5 shows the NOx desorption curves obtained with the catalysts of Examples 17 and 18.

CITED LITERATURE

[0338] WO 2020/0236879