Honeycomb filter for clarifying exhaust gas and method for manufacture thereof

• US 20070059484A1
• Filed: 07/09/2004
• Published: 03/15/2007
• Est. Priority Date: 07/11/2003
• Status: Active Grant

• Current Assignee: OHCERA Co. Ltd.
• Original Assignee: OHCERA Co. Ltd.
• Inventors: Fukuda, Masahiro, Takahashi, Masahide, Fukuda, Masaaki, Fukuda, Tsutomu, Yoko, Toshinobu
• Granted Patent: US 7,575,792 B2
• Time in Patent Office: Days
• US Class Current: 428/116
• CPC Class Codes: B01D 46/2429 of the honeycomb walls or cells
• CPC Class Codes: B01D 46/24491 Porosity
• CPC Class Codes: B01D 46/24494 Thermal expansion coefficient, heat capacity or thermal conductivity
• CPC Class Codes: B01D 46/247 of the cells
• CPC Class Codes: B01D 46/2474 of the walls along the length of the honeycomb
• CPC Class Codes: B01D 46/2482 Thickness, height, width, length or diameter
• CPC Class Codes: B01D 46/2484 Cell density, area or aspect ratio
• CPC Class Codes: C04B 2111/00793 as filters or diaphragms
• CPC Class Codes: C04B 2235/3201 Alkali metal oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3244 Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3272 Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint glass constituents C04B2235/36
• CPC Class Codes: C04B 2235/3472 Alkali metal alumino-silicates other than clay, e.g. spodumene, alkali feldspars such as albite or orthoclase, micas such as muscovite, zeolites such as natrolite
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/77 Density
• 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 35/465 : based on alkaline earth metal titanates
• CPC Class Codes: C04B 35/478 : based on aluminium titanates
• CPC Class Codes: C04B 35/632 : Organic additives
• CPC Class Codes: C04B 38/0006 : Honeycomb structures from one or more corrugated sheets by winding or stacking C04B38/0083
• CPC Class Codes: C04B 38/0009 : characterised by features relating to the cell walls, e.g. wall thickness or distribution of pores in the walls
• CPC Class Codes: C04B 38/0074 : expressed as porosity percentage
• CPC Class Codes: F01N 2330/06 : Ceramic, e.g. monoliths
• CPC Class Codes: F01N 2330/48 : characterised by the number of flow passages, e.g. cell density
• CPC Class Codes: F01N 3/0222 : the structure being monolithic, e.g. honeycombs
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y10T 428/24149 : Honeycomb-like

Abstract

To provide a honeycomb filter for cleaning exhaust gas, which is excellent in heat resistance and thermal shock resistance and has high thermal decomposition resistance and high mechanical strength and which is thus capable of being used with stability at high and fluctuating temperatures, and a process for its production.

A honeycomb filter for removing fine solid particles containing carbon as the main component in an exhaust gas, characterized in that the material for the honeycomb filter is an aluminum magnesium titanate sintered product obtained by firing at from 1000 to 1700° C. a formed product from a mixture comprising a Mg-containing compound, an Al-containing compound and a Ti-containing compound in the same metal component ratio as the metal component ratio of Mg, Al and Ti in aluminum magnesium titanate represented by the empirical formula Mg_xAl_{2(1−x)Ti(1+x)}O₅ (wherein 0<x<1), or a mixture comprising 100 parts by mass, as calculated as oxides, of the above-mentioned mixture and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK_1−y)AlSi₃O₈ (wherein 0≦y≦1).

Claims

1. A honeycomb filter for cleaning exhaust gas, which is a honeycomb filter for removing fine solid particles containing carbon as the main component in an exhaust gas, characterized in that the material for the honeycomb filter is an aluminum magnesium titanate sintered product obtained by firing at from 1000 to 1700°

C. a mixture comprising a Mg-containing compound, an Al-containing compound and a Ti-containing compound in the same metal component ratio as the metal component ratio of Mg, Al and Ti in aluminum magnesium titanate represented by the empirical formula Mg_xAl<sub>2(1−

x)</sub>Ti_(1+x)O₅ (wherein 0<

x<

1).

3. The honeycomb filter for cleaning exhaust gas according to claim 1, wherein the honeycomb filter has a wall thickness of 0.2 to 0.6 mm and a cell density of from 15 to 47 cells/cm², wherein the porosity of the partition wall is from 30 to 70%, and the thermal expansion coefficient is at most 3.0×

10<sup>−

6</sup>K<sup>−

1</sup>.

11. An apparatus for cleaning exhaust gas, characterized in that the honeycomb filter for cleaning exhaust gas as defined in claim 1 is accommodated in a can.

13. A method for cleaning diesel engine exhaust gas, comprising

passing the exhaust gas through the apparatus of claim 11.

2. A honeycomb filter for cleaning exhaust gas, characterized in that the material for the honeycomb filter is an aluminum magnesium titanate sintered product obtained by firing at from 1000 to 1700°

C. a mixture comprising 100 parts by mass, as calculated as oxides, of a mixture comprising a Mg-containing compound, an Al-containing compound and a Ti-containing compound in the same metal component ratio as the metal component ratio of Mg, Al and Ti in aluminum magnesium titanate represented by the empirical formula Mg_xAl<sub>2(1−

)</sub>Ti_(1+x)O₅ (wherein 0<

x<

1), and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula

(Na_yK<sub>1−

y)</sub>AlSi₃O₈ (wherein 0≦

y≦

1).

8. The honeycomb filter for cleaning exhaust gas according to claim 2, wherein the honeycomb filter has a wall thickness of 0.2 to 0.6 mm and a cell density of from 15 to 47 cells/cm², wherein the porosity of the partition wall is from 30 to 70%, and the thermal expansion coefficient is at most 3.0×

10<sup>−

6</sup>K<sup>−

1</sup>.

12. An apparatus for cleaning exhaust gas, characterized in that the honeycomb filter for cleaning exhaust gas as defined in claim 2 is accommodated in a can.

14. A method for cleaning diesel engine exhaust gas, comprising

passing the exhaust gas through the apparatus of claim 12.

4-7. -7. (canceled)

9. A process for producing a honeycomb filter for cleaning exhaust gas, characterized by preparing a mixture comprising a Mg-containing compound, an Al-containing compound and a Ti-containing compound in the same metal component ratio as the metal component ratio of Mg, Al and Ti in aluminum magnesium titanate represented by the empirical formula Mg_xAl₂₍₁₋

x)Ti_(1+x)O₅ (wherein 0<

x<

1), or a mixture comprising 100 parts by mass, as calculated as oxides, of such a mixture and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK<sub>1−

y</sub>)AlSi₃O (wherein 0≦

y≦

1), adding molding assistants to the mixture, followed by kneading to plasticize the mixture to make it extrusion-processable, and then extrusion processing it into a honeycomb structure, followed by firing at from 1000 to 1700°

C.

10. The process for producing a honeycomb filter for exhaust gas according to claim 9, wherein the average particle sizes of the respective components contained in the mixture are at most 30 μ

m.