JP2002504476A - Low CTE cordierite body having narrow pore size distribution and method for producing the same - Google Patents

Abstract

(57) Summary CTE of ≦ 4 × 10 ⁻⁷ / ° C. at 25-800 ° C., at least 85% pores with a pore diameter of 0.5-5.0 micrometers; or> 4-6 × 10 ⁻⁷ / ° C. A cordierite body having a CTE of at least 30% by volume, a porosity of at least 30% by volume, and a porosity of at least 85% with a pore diameter of 0.5-5.0 micrometers. Talc, Al ₂ O ₃ source, and kaolin, calcined kaolin, and / or silica, and optionally spinel, talc particle size ≦ 3.0 micrometers, Al ₂ O ₃ source particle size Is ≤2.0 micrometers, and kaolin, when the particle size is <2.0 micrometers, a raw material that is <35% by weight of the raw material is blended with vehicle and auxiliaries to prepare a plastic mixture. A green body is formed, dried and fired at 1370-1435 ° C. The talc particle size is <2.0 micrometers, the Al ₂ O ₃ source is <20% by weight of the raw material, and the dispersible high surface area Al ₂ O ₃ source having a particle size of <0.3 micrometer is <5.0 micrometers in the raw material. % By weight and if the particle size of the kaolin is <2.0 micrometers, the heating rate from 1150 ° C to 1275 ° C is> 200 ° C / hour. The talc particle size is ≦ 2.0 micrometers, the Al ₂ O ₃ source is <20% by weight of the raw material, and the dispersible high surface area Al ₂ O ₃ source having a particle size of <0.3 micrometer is <5.0 micron of the raw material. % By weight and if the particle size of the kaolin is <2.0 micrometers, the heating rate from 1150 ° C to 1275 ° C is> 50 ° C / hour and <600 ° C / hour. The source of Al ₂ O ₃ is <20% by weight of the raw material, the dispersible high surface area Al ₂ O ₃ source having a particle size of <0.3 micrometers is ≧ 5.0% by weight of the raw material, and the particle size of kaolin is ≦ 2.0%. In the case of micrometers, the heating rate from 1150 ° C. to 1275 ° C. is> 50 ° C./hour. If the particle size of kaolin is> 2.0 micrometers, the heating rate at 1150 ° C to 1275 ° C is ≦ 600 ° C / hour and> 30 ° C / hour.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] This application is related to US Provisional Patent Application No. 60/1998, filed February 25, 1998, entitled "Low CTE Cordierite Bodies with Narrow Pore Size Distribution and Methods for Producing the Same" by Gregory A. Merkel. Claims the benefits of 075,846.

The present invention relates to cordierite bodies having a unique combination of low coefficient of thermal expansion (CTE) and narrow pore size distribution. This is achieved by using a selected combination of raw materials and firing schedule. In particular, the cordierite body is a honeycomb structure that has been found to be used as a substrate for catalytic reactions and for filtration applications.

[0003] cordierite having a background honeycomb structure of the invention include, but are not limited to, a substrate for a catalyst for the conversion of exhaust gas of an automobile, for example, as a diesel particulate filter, or a heat exchanger Particularly suitable for use as a core. Cordierite is preferably used in these applications because of its good thermal shock resistance. Thermal shock resistance is inversely proportional to the coefficient of thermal expansion (CTE). That is, a honeycomb having a small thermal expansion has good thermal shock resistance, and can endure a wide temperature fluctuation range encountered in the above-mentioned application.

[0004] In some cases, such as with thin-walled honeycomb substrates, it is desirable to reduce total porosity to increase strength. However, such reduced porosity results in a reduced percentage of the washcoat containing the catalyst, and in some cases, reduces the number of substrates to deposit a desired thickness of washcoat layer. It becomes necessary to coat several times. This multiple coating process adds to the cost of the final product. Desirably, the cordierite body has a narrow pore size distribution of pores having a diameter of less than about 10 micrometers. The advantage of a narrow pore size distribution is that the distribution improves washcoat impregnation so that the desired thickness of the washcoat layer can be achieved in a single coating step without requiring multiple coating steps. .

[0005] To date, cordierite bodies with low CTE and a narrow pore size distribution in the range of less than 10 micrometers have not been achieved. For the reasons mentioned above, having a cordierite body having both of these properties would be highly desirable and would be an advance in the prior art. The present invention provides such a cordierite body and a method for producing the same.

[0006] In accordance with one aspect of the Summary of the Invention invention, there is provided a code Jieraito having a CTE of ≦ 4 × 10 ^-7 / ℃ at 25-800 ° C., at least 85% of its total pore 0.5-5.0 A cordierite body having an average pore size of micrometer is provided.

According to another aspect of the invention, the CTE is> 4-6 × 10 ⁻⁷ / ° C. at 25-800 ° C., the total porosity is at least 30% by volume, and at least 85% of the total pores A cordierite body having a% pore size of 0.5-5.0 micrometer is provided.

According to another aspect of the present invention, there is provided a method of manufacturing a cordierite body as described above, comprising: talc, an Al ₂ O ₃ forming source, and one or more of kaolin, calcined kaolin, and silica. And, optionally, intimately blending the spinel with a vehicle and a forming aid to prepare a plastic mixture. The average particle size of talc is ≦ 3.0 micrometers, and the average particle size of the Al ₂ O ₃ forming source is ≦ 2.0 micrometers. Kaolin, when present, is <35% by weight of the raw material when the particle size is <2.0 micrometers. A green body is formed, which is dried and 13
Fired at 70-1435 ° C. The talc has an average particle size of <2.0 micrometers, the Al ₂ O ₃ forming source is <20% by weight of the raw material, and the dispersible high surface area Al ₂ O ₃ forming source having a particle size of <0.3 micrometers is as described above. If the raw material is <5.0% by weight and the average particle size of kaolin is <2.0 micrometers, then the heating rate from 1150 ° C to 1275 ° C is> 200 ° C / hour. The talc has an average particle size of ≧ 2.0 micrometers, the Al ₂ O ₃ forming source is <20% by weight of the raw material, and the dispersible high surface area Al ₂ O ₃ forming source having an average particle size of <0.3 micrometers is used. If <5.0% by weight of the raw material and the average particle size of the kaolin is <2.0 micrometers, the heating rate from 1150 ° C to 1275 ° C is> 50 ° C / hour and <600 ° C / hour. The source of Al ₂ O ₃ is less than 20% by weight of the raw material, the dispersible high surface area Al ₂ O ₃ forming source having a particle size of <0.3 micrometers is ≧ 5.0% by weight of the raw material, and the average particle size of kaolin If the diameter is <2.0 microns, the heating rate from 1150 ° C to 1275 ° C is> 50 ° C / hour.
If the average particle size of kaolin is> 2.0 micrometers, the heating rate from 1150 ° C to 1275 ° C is <600 ° C / hour and> 30 ° C / hour.

[0009] The invention relates to a low thermal expansion or CTE measured at 25-800 ° C., about cordierite bodies having a unique combination of narrow pore size distribution. The cordierite body is manufactured by a method including selection of a specific combination of raw materials and firing conditions. According to the present invention, the CTE is the average expansion of 25-800 ° C. as measured by dilatometry. In a honeycomb, the CTE is the average expansion along a direction parallel to the length of the open passage.

Unless otherwise specified, a particular particle size is expressed as an average particle size. Particle size is measured by the sedimentation technique.

[0011] Porosity is the total porosity measured by mercury porosimetry and is expressed in volume percent.

[0012] The success of the present invention in obtaining a raw material low CTE and a very narrow pore size distribution between 0.5 and 5.0 micrometers maintains the use of fine talc in combination with certain raw materials and a low CTE. Based on firing schedule. By using fine talc, pores between 0.5 and 5.0 micrometers can be obtained with a very high fraction. However, finer talc tends to result in cordierite bodies having a higher CTE due to reduced microcrack formation. In order to return the CTE to the desired low value, the other ingredients must be specially selected and, for certain ingredient combinations, certain limits must be placed on the heating rate during firing.

About 49% to about 53% SiO ₂ , about 12% to about 16% MgO, and about 33% to about 38% Al ₂ O _{3 with} low expansion and narrow pore size distribution to achieve the cordierite composition, the raw material employed is talc, and Al ₂ O ₃ forming source, and one or more components of kaolin, calcined kaolin, and silica. If necessary, spinel may be a raw material.

The talc must have an average particle size of no more than 3.0 micrometers.

By Al ₂ O ₃ forming source is meant Al ₂ O ₃ itself or other material with low water solubility that converts to Al ₂ O ₃ when calcined. Examples of typical Al ₂ O ₃ forming sources include alumina, Al (OH) ₃ (also known as aluminum trihydrate or mineral gibbsite), or aluminum oxide hydroxide (aluminum monohydrate). Or the mineral boehmite or pseudo-boehmite).

The dispersible high surface area Al ₂ O ₃ forming source or component can be provided as a powder or as a sol. The dispersibility is as follows: agglomerates of very fine particles fall apart, about 0.
It means that it can be dispersed in constituent particles having an average particle size of less than 3 micrometers. High surface area means a surface area of greater than about 10 m ² / g, preferably greater than about 40 m ² / g. Such powders may include boehmite, pseudoboehmite, gamma phase alumina, delta phase alumina, or other so-called transition alumina.

[0017] The Al ₂ O ₃ forming source must have an average particle size of 2.0 micrometers or less, and preferably a specific surface area of greater than about 5 m ² / g. The amount of Al ₂ O ₃ forming source is preferably at least about 20% by weight of the raw material so that the range of heating rates can be maximized and still obtain a low CTE cordierite body.

When present, the average particle size of kaolin can be from about 0.2 micrometers to about 10 micrometers. However, its average particle size is about
If less than 2 micrometers, the amount of such kaolin used should be less than about 35% by weight of the total raw material loading. The balance of Al ₂ O ₃ required to form cordierite is provided by calcined kaolin or Al ₂ O ₃ forming sources, and the balance of SiO ₂ is provided by calcined kaolin or silica powder. The amount of the Al ₂ O ₃ forming source supplied as the dispersible high surface area Al ₂ O ₃ forming component is:
Preferably, it is at least about 5% by weight of the raw material charge.

The raw materials are blended with molding aids and vehicles that give the raw materials plastic formability and green strength when they are formed into cordierite bodies. When molding is performed by extrusion, extrusion aids are most commonly cellulose ether organic binders and lubricants such as diglycol stearate, sodium, ammonium, but the invention is not limited thereto.

The organic binder contributes to the plasticity of the mixture for forming into an object. The plasticized organic binder according to the invention refers to a cellulose ether binder. Examples of typical organic binders according to the present invention include methylcellulose, ethylhydroxyethylcellulose, hydroxybutylmethylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxybutylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, sodium carboxymethylcellulose, And mixtures thereof. Methylcellulose and / or methylcellulose derivatives are particularly suitable as organic binders in practicing the present invention, with methylcellulose, hydroxypropylmethylcellulose or combinations thereof being preferred. Preferred components of the cellulose ether are Methocel A4M from Dow Chemical Company,
F4M, F240, and K75M. Methocel A4M is methylcellulose, while Methocel F4M, F240, and K75M are hydroxypropyl methylcellulose.

[0021] The content of organic binder is generally from about 3% to about 6%, based on the raw materials.

The vehicle can be inorganic, that is, not exclusively, typically about 28% to about 46%, mostly water, or organic. Preferably, water is used, but alternatively, volatile organic liquids, such as lower alkanols, may be used in whole or in part as desired.

[0023] The weight percentages of organic binder, vehicle and other additives are calculated as additional additives with respect to the raw materials.

Next, the mixture is formed into a green body. The preferred forming method is extrusion through a die. Extrusion can be performed using a hydraulic ram extrusion press, or a two-stage degassing single auger extruder, or a twin screw mixer with a die assembly attached to the discharge end. In this mixer, the appropriate screw element is selected according to the material and other processing conditions to generate sufficient pressure to extrude the batch material through the die.

The cordierite bodies according to the present invention can have any convenient size and shape. However, the method of the present invention is particularly suitable for producing a cellular monolith such as a honeycomb. Cellular bodies have been found to be used in numerous applications, such as catalyst supports, filters such as diesel particulate filters, molten metal filters, heat exchanger cores, and the like.

In general, the cell density of honeycombs ranges from about 245 cells / cm ² (about 1500 cells / in ² ) to 15 cells / cm ² (about 100 cells / in ² ). Wall (web) thickness typically ranges from about 0.07 mm to about 0.6 mm (about 3 mils to about 25 mils).
The outer dimensions and shape of the object are controlled by the space available for mounting, the engine size, etc. in the application, for example, in automotive applications. The present invention is particularly beneficial for honeycombs having very thin walls, for example, <5 mils. For certain mixtures of the present invention, especially those containing clay, alumina, and talc, all of which have an average particle size of <3 micrometers, a thinner walled honeycomb, for example, 0.025-0.1 mm (1- Honeycomb with 4 mil) walls can be manufactured.

The green body is then dried according to conventional methods for a fired cordierite body, such as a drying oven or dielectric drying.

Next, the dried body is fired at a temperature of about 1370 ° C. to about 1435 ° C. The firing conditions are different depending on the combination of the raw materials.

For example, the talc has an average particle size of less than 2.0 micrometers, the amount of Al ₂ O ₃ forming source is less than 20% by weight of the raw material, and the dispersant has an average particle size of less than about 0.3 micrometers. The surface area Al ₂ O ₃ forming source, if present, comprises less than about 5.0% by weight of the raw material, and if the average particle size of kaolin is less than about 2.0 micrometers, the formation and reduction of microcracks. To obtain the microstructure required for CTE, the heating rate between 1150 ° C and 1275 ° C is greater than 200 ° C / hour.

A dispersion wherein the average particle size of the talc is greater than about 2.0 micrometers, the amount of Al ₂ O ₃ forming source is less than about 20% by weight of the raw material, and the average particle size is less than about 0.3 micrometers. A high surface area Al ₂ O ₃ forming source, if present, comprises less than about 5.0% by weight of the raw material, and if the average particle size of kaolin is less than about 2.0 micrometers, from 1150 ° C. to 1275%. The heating rate up to 50 ° C is greater than about 50 ° C / hour,
It is less than 0 ° C / hour.

The amount of the Al ₂ O ₃ forming source is less than about 20% by weight of the raw material, and a dispersible high surface area Al ₂ O ₃ forming source having an average particle size of less than about 0.3 micron is used to provide about 5.0% If present in an amount greater than or equal to the weight percent and the average particle size of kaolin is less than about 2.0 micrometers, the heating rate between 1150 ° C and 1275 ° C is greater than about 50 ° C / hour.

If the average particle size of kaolin is greater than about 2.0 micrometers, the heating rate between 1150 ° C. and 1275 ° C. is less than about 600 ° C./hour and greater than about 30 ° C./hour.

The fired body is then cooled to room temperature in a practically short time.

The cordierite bodies of the present invention include: (1) an average coefficient of thermal expansion at 25-800 ° C. of ≦ 4 × 10 ⁻⁷ / ° C .; or (2)> 4 × 10 ⁻⁷ / ° C. but ≦ 6. Characterized by an average coefficient of thermal expansion of × 10 ⁻⁷ / ° C. and a total porosity of about 30% by volume or more. If the CTE is less than 4 × 10 ⁻⁷ / ° C., the total porosity can have any value, but is preferably greater than about 18%. In all cases, at least about 85% of all pores fall between about 0.5 micrometers and about 5.0 micrometers.

The porous body having microcracks of the present invention has found use as a catalyst substrate because its pore size distribution is useful for impregnating and retaining a washcoat. The method of the present invention is particularly suitable for producing high cell density, 0.152 mm (<0.006 inch) thin wall and 0.102 mm (<0.004 inch) ultra-thin wall honeycomb bodies. In addition, the porosity and pore size distribution of the cordierite bodies produced by the method of the present invention are more sensitive to changes in heating rate during firing than for cordierite bodies produced by conventional methods, including the use of coarser talc. Not so sensitive. It is believed that these properties result in less variation in washcoat loading for substrates fired at various locations in the furnace. A narrow pore size distribution may also be useful in certain filtration applications.

The following non-limiting examples are presented in order to illustrate the invention in more detail. All parts, parts, and percentages are on a weight basis unless otherwise indicated.

In all of the following examples and comparative examples, the raw materials were dry-loaded with about 3-6% methylcellulose binder and about 0.5-1.0% sodium stearate lubricant and then stainless steel It was mixed with about 30-46% water in the maller for about 20 minutes. The resulting plasticized mixture is subsequently extruded as a honeycomb body having a wall thickness of about 62 cells / cm ² (about 400 cells / square inch) and about 0.152 mm (about 0.006 inches). The extrudate was wrapped in aluminum foil and dried at about 85 ° C. for about 72 hours. The honeycomb was cut to a length of about 10.16 cm (4 inches) and placed on alumina or coarse alumina sand on a cordierite pallet in an electric furnace.

The combinations of raw materials are listed in Table 1. The average particle size was determined by sedimentation analysis (Sedigraph ana
lysis). The firing schedule and physical properties of the fired products are shown in Table 2.

Examples 1-3 show a combination of 1.6 micrometer talc, 0.4 micrometer alpha alumina, and 4.5 micrometer crystalline silica, when fired at a wide range of heating rates, low CTE, high It shows that cordierite bodies of the present invention having a total porosity and a total porosity greater than 85% with a pore size between 0.5 and 5.0 micrometers are obtained.

Comparative Examples 4-6 show that the median pore size increases when the average particle size of talc combined with 0.4 micrometer alpha alumina and 4.5 micrometer crystalline silica is increased to 6.1 micrometer. However, the pore size distribution is wider, indicating that the volume of pores between 0.5 and 5.0 micrometers is less than 85% of the total pores.

Examples 7 and 8 demonstrate that a mixture of fine talc, having an average particle size of 1.6 micrometers, in combination with fine kaolin, fine alumina, and calcined kaolin at a rate between 250-600 ° C./hour. When heated from 1150 ° C to 1275 ° C, with a very narrow pore size distribution and a total porosity greater than 30%, more than 85% of the total pores fall between 0.5 and 5.0 micrometers4. -
This shows that a CTE of between 6 × 10 ⁻⁷ / ° C. is obtained. Examples 9 to 11 show that this combination of raw materials, when heated between 1150 ° C and 1275 ° C at a rate of more than 600 ° C / hour, leads to an 85% This shows that a CTE of less than 4 × 10 ⁻⁷ / ° C. can be obtained with a larger total pore. In Comparative Examples 12 to 14, when the cordierite body composed of these raw materials was heated at a rate of less than 250 ° C./hour, the CTE exceeded 6 × 10 ⁻⁷ / ° C.,
Therefore, it is not the present invention.

Examples 15 and 16 show that when the heating rate at 1150-1275 ° C. is greater than about 50 ° C./hour, but less than about 600 ° C./hour, the fine particles have an average particle size of about 2.2 micrometers. It shows that talc is used in combination with fine kaolin, calcined kaolin, and fine alumina. In Comparative Example 17, the heating rate was 5 at 1150-1275 ° C.
If it is less than 0 ° C./hour, it indicates that the CTE is greater than 6 × 10 ⁻⁷ / ° C. Comparative Examples 18 and 19 show that when the heating rate between 1150 ° C. and 1275 ° C. is faster than about 500 ° C./hour, the pores become excessively coarse and the total pores between 0.5 and 5.0 micrometers are used. The percentage is less than 85%.

Comparative Examples 20 and 21 show that when 3.4 micrometer talc is used in combination with fine kaolin, fine alumina, and calcined kaolin, the average particle size is between 0.5 micrometers and 5.0 micrometers. 85% of all pores
It indicates that the roughness becomes less than.

Comparative Example 22 shows that 4.2 micrometer talc was used in combination with fine kaolin, fine alumina, and calcined kaolin between 1150 ° C. and 1275 ° C.
When fired at a heating rate lower than 150 ° C./hour, a narrow pore size distribution is obtained, indicating that the CTE is increased more than 6 × 10 ⁻⁷ / ° C. Comparative Examples 23 and 24 show that if this raw material combination is fired faster than 150 ° C / hr between 1150 ° C and 1275 ° C to maintain a CTE of less than 6 × 10 ^-7 / ° C. The uniform pore size indicates that the percentage of total pores between 0.5 and 5.0 micrometers is coarse such that it is less than 85%.

Examples 25-30 partially replace 0.4 micrometer of alpha alumina with at least 5% boehmite having a surface area of about 180 m ² / g and a finely dispersed particle size of about 0.125 micrometers. When combined with 1.6 micron talc, 0.9 micron kaolin, and calcined kaolin, such cordierite bodies are heated between 1150 ° C and 1275 ° C faster than 50 ° C / hour This shows that cordierite bodies having a CTE of less than 4 × 10 −7 / ° C. and a porosity between 0.5 and 5.0 μm, greater than 85% of the total porosity, are obtained. Thus, by adding this boehmite to a combination of fine talc, fine kaolin, calcined kaolin, and alpha alumina raw materials, a lower firing rate is used while maintaining the desired combination of low CTE and narrow pore size distribution. it can.

Examples 31 and 32 show that when fired between 1150 ° C. and 1275 ° C. at a heating rate of greater than about 30 ° C./hr, but less than about 600 ° C./hr, 1.6 micrometers of talc and more Regarding the raw material combination of coarse 7.4 micron kaolin with 0.4 micron alpha alumina, a very narrow pore size distribution and 30
This shows that a low CTE cordierite body having a total porosity of not less than% can be obtained. The ability to use fine talc with coarse kaolin and still obtain low CTE is not expected. Comparative Example 33 shows that when the heating rate is less than about 30 ° C./hour between 1150 ° C. and 1275 ° C., the CTE becomes greater than 6 × 10 ⁻⁷ / ° C. Comparative Examples 34 and 35 show that when the heating rate is above about 600 ° C./hour, the average particle size is so coarse that pores between 0.5 and 5.0 micrometers are no longer at least 85% of the total pores It is shown that.

Comparative Examples 36-38 show that when coarse 4.5 micron alpha alumina powder is used in combination with fine talc, fine kaolin, and calcined kaolin, the CTE is 6 × 10, even for slow or fast heating rates. ^-7 / ° C.

Although the present invention has been described in detail with reference to certain illustrative and specific embodiments, the present invention is not limited to such, and the spirit of the invention and the appended patents It will be appreciated that other forms may be used without departing from the scope of the claims.

Claims (7)

[Claims] 1. A method of producing a cordierite body, comprising: a) one of talc, an Al ₂ O ₃ forming source, kaolin, calcined kaolin, and silica, optionally with spinel. One or more of a cordierite-forming raw material containing a component, an average particle diameter of the talc is less than about 3.0 microns, average grain size of the Al ₂ O ₃ forming sources is less than or equal to about 2.0 micrometers, there If so, selecting a raw material whose amount of kaolin is less than about 35% by weight of said raw material when the average particle size of said kaolin is less than about 2.0 micrometers; b) Intimately blending with a vehicle and a molding aid in an amount effective to provide plastic formability and green strength to the plastic mixture, and then c) forming said raw material into a green body; d) Dry the unfired body Is, e) comprises the steps of firing the yet-fired at a temperature from about 1370 ° C. to about 1435 ° C., an average particle diameter of the talc is less than 2.0 micrometers, the amount of the Al ₂ O ₃ forming source Is less than 20% by weight of the raw material, and a dispersible high surface area Al ₂ O ₃ forming source having an average particle size of less than about 0.3 micrometers is present, if present.
If the average particle size of the kaolin is less than about 2.0 micrometers, then the heating rate between 1150 ° C and 1275 ° C is greater than about 200 ° C / hour; A dispersible high surface area having an average particle size of about 2.0 micrometers or greater, wherein the amount of the Al ₂ O ₃ forming source is less than about 20% by weight of the raw material, and having an average particle size of less than about 0.3 micrometers; The Al ₂ O ₃ forming source, if present, comprises less than about 5.0% by weight of the raw material, and if the average particle size of the kaolin is less than about 2.0 micrometers, at 1150 ° C. and 1275 ° C. The heating rate is greater than about 50 ° C./hour and less than about 600 ° C./hour; the amount of the Al ₂ O ₃ forming source is less than about 20% by weight of the raw material; dispersible high surface area Al ₂ O ₃ forming source having a mean particle size of less than the When constituting at least about 5.0% by weight of the raw material and the average particle size of the kaolin is less than about 2.0 micrometers, the heating rate between 1150 ° C and 1275 ° C is greater than about 50 ° C / hour. If the average particle size of the kaolin is greater than about 2.0 micrometers, 115
The heating rate between 0 ° C. and 1275 ° C. is less than about 600 ° C./hour and greater than about 30 ° C./hour, whereby from about 49% to about 53% SiO ₂ , a cordierite body having a composition consisting essentially of about 33% to about 38% Al ₂ O ₃ and about 12% to about 16% MgO, the set of properties being: 25-800. ° C
Pores having an average coefficient of thermal expansion of ≦ 4 × 10 ⁻⁷ / ° C., and a pore diameter of which about 85% or more of all pores are between about 0.5 μm and about 5.0 μm; or 2
> 4 × 10 ⁻⁷ / ° C at 5-800 ° C, but average thermal expansion coefficient of ≦ 6 × 10 ⁻⁷ / ° C, total porosity of about 30% by volume or more, and about 85% or more of all pores Is about 0.5 micrometers and about 5.0
Having a pore diameter of between micrometers: a method characterized by producing a cordierite body having one of the following: 2. The amount of said Al ₂ O ₃ forming source being at least about 20% by weight of said raw material.
The method of claim 1, wherein 3. Kaolin is present as a raw material, has an average particle size of less than about 2.0 micrometers, and the amount of said Al ₂ O ₃ forming source is less than about 20% by weight of said raw material. The method according to claim 1, wherein 4. The method of claim 3, wherein the amount of said dispersible high surface area Al ₂ O ₃ forming source is at least about 5.0% by weight of said raw material. 5. The method according to claim 4, wherein said dispersible high surface area Al ₂ O ₃ forming source is selected from the group consisting of boehmite, pseudo boehmite, and combinations thereof. 6. An average coefficient of thermal expansion of ≦ 4 × 10 ⁻⁷ / ° C. at 25-800 ° C. and at least about 85% of all pores have a pore diameter between about 0.5 micrometers and about 5.0 micrometers. A cordierite body characterized by having pores having the same. 7. A cordierite body having an average coefficient of thermal expansion of> 4 × 10 ⁻⁷ / ° C. at 25-800 ° C., but ≦ 6 × 10 ⁻⁷ / ° C., and a total porosity of about 30% by volume or more. A cordierite body, wherein at least about 85% of all pores have a pore diameter between about 0.5 micrometers and about 5.0 micrometers.