Reduction-catalyst-coated diesel particle filter having improved characteristics

Patent metadata

Field	Value
Publication number	US-9347354-B2
Application number	US-201113583516-A
Country	US
Kind code	B2
Filing date	Mar 30, 2011
Priority date	Apr 14, 2010
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

An SCR-catalytically active diesel particle filter having a ceramic wall flow filter substrate with inflow channels, outflow channels, walls separating the inflow and outflow channels, and two coatings. The first coating is applied in inflow channels, is composed of high-melting point materials, and closes the inflow sides of pores in walls connecting the inflow channels and outflow channels to soot particles without preventing passage of gaseous exhaust gas constituents. The second coating is within the walls between inflow channels and outflow channels, and effectively catalyzes the selective reduction of nitrogen oxides when in the presence of a reducing agent. The particle filter displays excellent banking-up pressure properties combined with high filtration efficiency and good regeneration properties; and displays good aging stability of NOx conversion activity.

First claim

The invention claimed is:

1. A diesel particle filter, comprising:
a ceramic wall flow filter substrate comprising inflow channels open at a first end of the wall flow filter substrate, outflow channels open at a second end of the wall flow filter substrate, and channel walls extending between the inflow channels and the outflow channels, the channel walls comprising pores that extend from openings at an inflow side to openings at an outflow side;
a first coating in the inflow channels, the first coating forming closures at pore openings at the inflow sides of the channel walls that inhibit soot particles from entering the pores at the inflow sides without preventing passage of gaseous exhaust gas constituents through the pores; and
a second coating inside the channel walls, the second coating being one that effectively catalyzes selective reduction of nitrogen oxides when in the presence of a reducing agent.

2. The diesel particle filter as claimed in claim 1 , wherein the materials used in the first coating do not have any oxidation-catalytic activity with ammonia.

3. The diesel particle filter as claimed in claim 2 , wherein the second coating contains one or more SCR-catalytically active components selected from the group consisting of:
(a) iron- and/or copper-exchanged zeolite compounds selected from among MOR, USY, ZSM-5, ZSM-20, beta-zeolite, CHA, FER, and mixtures thereof; or
(b) iron- and/or copper-exchanged zeolite-like compounds selected from among SAPO-34, ALPO-34, and mixtures thereof; or
(c) vanadium oxide, titanium oxide, tungsten oxide, molybdenum oxide, cerium oxide, zirconium oxide, niobium oxide, iron oxide, manganese oxide, mixtures thereof, and mixed oxides thereof; or
(d) mixtures of at least two of (a), (b), and (c).

4. The diesel particle filter as claimed in claim 2 , wherein
the first coating comprises, as a majority, one or more oxides,
the d 50 of the particle size distribution of the oxides in the first coating is equal to or greater than the d 5 of the pore size distribution of the pores in the channel walls of the wall flow filter substrate,
the d 90 of the particle size distribution of the oxides in the first coating is equal to or greater than the d 95 of the pore size distribution of the pores in the channel walls of the wall flow filter substrate,
the d 50 or the d 90 of the particle size distribution of the oxides is the particle size at which 50% or 90%, respectively, of the total volume of the oxides contains only particles having diameters smaller than or equal to the value indicated as d 50 or d 90 , respectively, and
the d 5 or the d 95 of the pore size distribution of the wall flow filter substrate is the pore size at which 5% or 95%, respectively, of the total pore volume that can be determined by mercury porosimetry is formed of pores having diameters smaller than or equal to the value indicated as d 5 or d 95 , respectively.

5. The diesel particle filter as claimed in claim 2 , wherein the first coating comprises:
as a majority, one or more oxides; and
palladium, as an oxidation-catalytically active component.

6. The diesel particle filter as claimed in claim 1 , wherein the second coating contains one or more SCR-catalytically active components selected from the group consisting of:
(a) iron- and/or copper-exchanged zeolite compounds selected from among MOR, USY, ZSM-5, ZSM-20, beta-zeolite, CHA, FER, and mixtures thereof; or
(b) iron- and/or copper-exchanged zeolite-like compounds selected from among SAPO-34, ALPO-34, and mixtures thereof; or
(c) vanadium oxide, titanium oxide, tungsten oxide, molybdenum oxide, cerium oxide, zirconium oxide, niobium oxide, iron oxide, manganese oxide, mixtures thereof, and mixed oxides thereof; or
(d) mixtures of at least two of (a), (b), and (c).

7. The diesel particle filter as claimed in claim 6 , wherein
the first coating comprises, as a majority, one or more oxides
the d 50 of the particle size distribution of the oxides in the first coating is equal to or greater than the d 5 of the pore size distribution of the pores in the channel walls of the wall flow filter substrate,
the d 90 of the particle size distribution of the oxides in the first coating is equal to or greater than the d 95 of the pore size distribution of the pores in the channel walls of the wall flow filter substrate,
the d 50 or the d 90 of the particle size distribution of the oxides is the particle size at which 50% or 90%, respectively, of the total volume of the oxides contains only particles having diameters smaller than or equal to the value indicated as d 50 or d 90 , respectively, and
the d 5 or the d 95 of the pore size distribution of the wall flow filter substrate is the pore size at which 5% or 95%, respectively, of the total pore volume that can be determined by mercury porosimetry is formed of pores having diameters smaller than or equal to the value indicated as d 5 or d 95 , respectively.

8. The diesel particle filter as claimed in claim 6 , wherein
the wall flow filter substrate comprises silicon carbide, cordierite, or aluminum titanate, and
the pores present in the channel walls between inflow and outflow channels have an average diameter in the range from 5 to 50 μm.

9. The diesel particle filter as claimed in claim 6 , wherein
the first coating comprises, as a majority, a fiber material comprising fibers with an average length in the range from 50 to 250 μm, and an average mass-based diameter equal to or smaller than the d 50 of the pore size distribution of the pores in the channel walls of the wall flow filter substrate,
the d 50 of the pore size distribution of the pores in the channel walls of the wall flow filter substrate is the pore size at which 50% of the total pore volume that can be determined by mercury porosimetry is formed of pores having diameters smaller than or equal to the value indicated as d 50 .

10. The diesel particle filter as claimed in claim 1 , wherein
the first coating comprises, as a majority, one or more oxides,
the d 50 of the particle size distribution of the oxides in the first coating is equal to or greater than the d 5 of the pore size distribution of the pores in the channel walls of the wall flow filter substrate,
the d 90 of the particle size distribution of the oxides in the first coating is equal to or greater than the d 95 of the pore size distribution of the pores in the channel walls of the wall flow filter substrate,
the d 50 or the d 90 of the particle size distribution of the oxides is the particle size at which 50% or 90%, respectively, of the total volume of the oxides contains only particles having diameters smaller than or equal to the value indicated as d 50 or d 90 , respectively, and
the d 5 or the d 95 of the pore size distribution of the wall flow filter substrate is the pore size at which 5% or 95%, respectively, of the total pore volume that can be determined by mercury porosimetry is formed of pores having diameters smaller than or equal to the value indicated as d 5 or d 95 , respectively.

11. The diesel particle filter as claimed in claim 10 , wherein the oxides in the first coating have a particle size distribution having a d 50 greater than or equal to 5 μm and a d 90 greater than or equal to 20 μm.

12. The diesel particle filter as claimed in claim 11 , wherein the oxides in the first coating are selected from the group consisting of aluminum oxide, rare earth metal-stabilized aluminum oxide, rare earth metal sesquioxide, and mixtures thereof.

13. The diesel particle filter as claimed in claim 12 , wherein the first coating has a layer thickness of f

Assignees

• Pfeifer Marcus
• Basso Stephan
• Dornhaus Franz
• Umicore Ag & Co Kg

Inventors

• Pfeifer Marcus
• Basso Stephan
• Dornhaus Franz

Classifications

• B01D2257/404

  Nitrogen oxides other than dinitrogen oxide · CPC title

• B01D53/9418

  for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas · CPC title

• Y02T10/24

  Cross-Sectional Technologies · mapped topic

• B01D2255/20738

  Iron · CPC title

• B01D2255/20776

  Tungsten · CPC title