Material for NOx trap support

• US 20030040432A1
• Filed: 08/15/2001
• Published: 02/27/2003
• Est. Priority Date: 08/15/2001
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Beall, Douglas M., Lakhwani, Shahid G.
• Granted Patent: US 6,677,272 B2
• Time in Patent Office: Days
• US Class Current: 502/332
• CPC Class Codes: B01D 2253/104 Alumina
• CPC Class Codes: B01D 2253/3425 Honeycomb shape
• CPC Class Codes: B01D 2257/404 Nitrogen oxides other than dinitrogen oxide
• CPC Class Codes: B01D 53/02 by adsorption, e.g. preparative gas chromatography solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01
• CPC Class Codes: B01D 53/9431 Processes characterised by a specific device
• CPC Class Codes: B01J 20/0211 Compounds of Ti, Zr, Hf
• CPC Class Codes: B01J 20/0229 Compounds of Fe
• CPC Class Codes: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/06 comprising oxides or hydroxides of metals not provided for in group B01J20/04
• CPC Class Codes: B01J 20/08 comprising aluminium oxide or hydroxide; comprising bauxite
• CPC Class Codes: B01J 20/2803 Sorbents comprising a binder, e.g. for forming aggregated, agglomerated or granulated products
• CPC Class Codes: B01J 20/28045 Honeycomb or cellular structures; Solid foams or sponges
• CPC Class Codes: B01J 20/3042 Use of binding agents; addition of materials ameliorating the mechanical properties of the produced sorbent
• CPC Class Codes: B01J 20/3204 Inorganic carriers, supports or substrates
• CPC Class Codes: B01J 20/3236 containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts
• CPC Class Codes: B01J 21/04 Alumina
• CPC Class Codes: B01J 21/10 Magnesium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 2220/42 Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: B01J 23/002 Mixed oxides other than spinels, e.g. perovskite
• CPC Class Codes: B01J 23/745 Iron
• CPC Class Codes: B01J 2523/00 : Constitutive chemical elements of heterogeneous catalysts
• CPC Class Codes: B01J 2523/22 : Magnesium
• CPC Class Codes: B01J 2523/31 : Aluminium
• CPC Class Codes: B01J 2523/47 : Titanium
• CPC Class Codes: B01J 2523/842 : Iron
• CPC Class Codes: C04B 2111/00793 : as filters or diaphragms
• CPC Class Codes: C04B 2111/0081 : as catalysts or catalyst carriers
• CPC Class Codes: C04B 2235/3206 : Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 : Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3222 : Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
• CPC Class Codes: C04B 2235/3234 : Titanates, not containing zirconia
• CPC Class Codes: C04B 2235/3272 : Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
• CPC Class Codes: C04B 2235/6562 : Heating rate
• CPC Class Codes: C04B 2235/6567 : Treatment time
• CPC Class Codes: C04B 2235/77 : Density
• CPC Class Codes: C04B 2235/80 : Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 2235/96 : Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 2235/9607 : Thermal properties, e.g. thermal expansion coefficient
• CPC Class Codes: C04B 35/443 : Magnesium aluminate spinel
• CPC Class Codes: C04B 35/478 : based on aluminium titanates
• CPC Class Codes: C04B 38/0006 : Honeycomb structures from one or more corrugated sheets by winding or stacking C04B38/0083
• CPC Class Codes: C04B 38/0054 : the pores being microsized or nanosized
• CPC Class Codes: C04B 38/0074 : expressed as porosity percentage

Abstract

A ceramic support element for a NOx trap which includes a NOx storage component comprising an alkali metal, the ceramic support having a composition lying within a ternary system selected from the group consisting of Al₂TiO₅—MgTi₂O₅—MgAl₂O₄ and Al₂TiO₅—FeTiO₅—Al₂O₃, a coefficient of thermal expansion (22-800° C.) of less than 20×10⁻⁷/° C. and a modulus of rupture as measured on a solid rod of circular cross section of greater than 1000 pounds per square inch.

Claims

1. A ceramic support for a NOx trap which includes a NOx storage component comprising an alkali metal, the ceramic support having a composition lying within a ternary system selected from the group consisting of Al₂TiO₅—

MgTi₂O₅—

MgAl₂O₄ and Al₂TiO₅—

FeTiO₅—

Al₂O₃, the ceramic support characterized by a modulus of rupture strength as measured on a solid rod of circular cross section of greater than 1000 pounds per square inch and a coefficient of thermal expansion (22-800°

C.) of less than 20×

10<sup>−

7</sup>/°

C.

2. The ceramic support of claim 1 wherein the composition is within the ternary system Al₂TiO₅—

MgTi₂O₅—

MgAl₂O₄.

3. The ceramic support of claim 2 wherein the composition consists essentially, in terms of weight percent on an oxide basis, of 15 to 90 wt. % Al₂TiO₅, 2 to 45 wt. % MgTi₂O₅, and 5 to 55 wt. % MgAl₂O₄.

4. The ceramic support of claim 1 wherein the composition is within the ternary system Al₂TiO₅—

FeTiO₅—

Al₂O₃.

5. The ceramic support of claim 4 wherein the composition consists essentially, in terms of weight percent on an oxide basis, of 35 to 85 wt. % Al₂TiO₅, 2 to 35 wt. % FeTiO₅, and 5 to 35 wt. % Al₂O₃.

6. The ceramic support of claim 1 wherein the alkali metal is selected from the group consisting of potassium, sodium, lithium, cesium, rubidium, and francium.

7. The ceramic support of claim 6 wherein the alkali metal is potassium.

8. The ceramic support of claim 1 wherein the NOx storage component further comprises a component selected from the group consisting of alkaline earth metals, rare earth metals and combinations thereof.

9. The ceramic support of claim 8 wherein the NOx storage component is a combination of an alkaline metal and an alkaline earth metal.

10. The ceramic support of claim 1 wherein the support is a honeycomb structure.

11. The ceramic support of claim 1 wherein the coefficient of thermal expansion (22-800°

C.) of less than 10×

10<sup>−

7</sup>/°

C.

12. The ceramic support of claim 1 wherein the modulus of rupture strength is greater than 2000 pounds per square inch.