JPS5915015B2 - Transition alumina-based hollow catalyst support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transition alumina hollow catalyst carrier, and more particularly to a transition alumina hollow catalyst carrier having extremely large pore volume and specific surface area.

Conventionally, ceramic hollow structures, especially multi-cell structures, have a large number of parallel and uniform gas flow paths, resulting in very low pressure loss, ρJ・, and good gas flow distribution within the groove structure, as well as thin walls. The catalyst carrier has various advantages such as a large effective surface area per unit weight, high strength despite being lightweight, and excellent heat resistance.
It has applications such as supports, heat exchangers, insulation materials, and soundproofing materials.
In particular, it is attracting attention as a catalyst carrier for automobile exhaust gas treatment and denitrification because it is an integrated product with good impact resistance and abrasion resistance.

Raw materials for these ceramic structures include cordierite, which is obtained by kneading and firing talc, bentonite, α-alumina, etc., spodumene, α-alumina, titania,
Zirconia, mullite, calcined kaolin, etc. are used.

Especially cordierite, spodumene, α-alumina,
A ceramic structure made of musito has low thermal expansion and excellent mechanical strength, and has excellent properties as a catalyst carrier.

However, these structures generally have a specific surface area of 5 r
rl/g or less and the pore volume is as small as 0.2 CC7g or less, the ability to adhere and support catalytically active substances is poor, and as it is, it cannot be said to be suitable as a catalyst carrier.

Therefore, in order to increase the adhesion and support of active substances and improve the catalytic properties, there is a method of coating the thin wall surface of the ceramic structure with activated alumina, which has a high catalyst support ability, by dipping or spraying. It is running.

However, since the carrier treated in this way does not improve the adhesion of activated alumina to the thin wall surface of the structure, the adhesion of activated alumina is extremely weak, and therefore, during use, the The disadvantage is that the alumina coating layer peels off and the durability of the catalyst is difficult to expect.

In contrast, the present invention overcomes the drawbacks of the catalyst carrier made of the known ceramic hollow structure as described above, and
The object of the present invention is to provide a transition alumina-based hollow catalyst carrier which has an integrally molded substrate, has a large specific surface area and pore volume, and has excellent catalyst support and catalytic activity.

That is, the present invention is a fired body that is integrally molded by extrusion molding using powder containing re-waterable alumina as a raw material, and is fired and activated after being treated for re-watering, the main component of which is transition alumina, and the porosity is low. is 3% or more, and the specific surface area is 5 m'/
9 or more, a bulk density of 0.1 to 1.2 g/cnl, a pore volume of o, 3 crl/g or more, and having at least one opening in the extrusion direction. It provides a carrier.

In this text, transition alumina is an intermediate alumina with a large specific surface area identified in the form of η, γ, X1δ, θ-forms, etc. by X-ray diffraction, and is mainly γ-alumina.

Hollow-shaped structures obtained by extrusion molding range from pipe-shaped extrusion-molded products with one round, rectangular, or other irregularly shaped holes to so-called multi-cell structures with 400 to 600 holes per square inch. (Honeycomb) structures are also included.

The transition alumina hollow catalyst carrier of the present invention will be explained in detail below.

Re-waterable alumina, which is a raw material for the catalyst carrier of the present invention, is transitional alumina other than α-alumina obtained by thermally decomposing alumina hydrate, such as ρ-alumina and amorphous alumina. The obtained alumina hydrate such as alumina trihydrate is brought into contact with hot gas at about 400 to 1200°C for usually a fraction of a second to 10 seconds, or the alumina hydrate is heated to about 250 to 900°C under reduced pressure. Usually about 0 can be obtained by heating and holding for 1 minute to 4 hours.
．． Those containing re-waterable alumina, such as those having an inherited weight loss of 5 to 15 weight units.

Re-waterable alumina is generally used with a particle size of about 50μ or less, and in the aggregate constituting the hollow catalyst carrier, it has a particle size of at least about 10 or more, preferably 20 or more, more preferably 30 or more. used above.

Aggregate constituents other than rewaterable alumina used as raw materials in the present invention are not particularly limited, but include α-alumina, silica, alumina hydrate, clay, talc, bentonite, diatomite, and zeolite. , cordierite,
These include inorganic substances known as catalyst carrier materials such as spodumene, titania, zirconia, silica sol, alumina sol, and mullite, as well as combustible substances and various catalyst components.

These aggregate components other than rewaterable alumina are used in an aggregate width of less than about 90 mm, preferably 80 mm, and more preferably 70 mm.

Combustible substances are added and mixed into the aggregate composition when increasing the pore volume of the thin walls of the final product, the hollow catalyst carrier. Any combustible material can be used.

Examples of such combustible substances include wood chips, cork granules, coal powder, activated carbon, charcoal, crystalline cellulose powder, methylcellulose, carboxymethylcellulose, starch, sucrose, gluconic acid, polyethylene glycol, polyvinyl alcohol, polyacrylamide, polyethylene, and polystyrene. etc. and mixtures thereof.

The larger the amount of the above-mentioned combustible substance added to the raw material alumina, the larger the macropore volume of the thin wall of the catalyst carrier, which is the final product, can be increased. Since this reduces the strength, the type and amount of the combustible substance to be added may be adjusted depending on the use of the catalyst carrier.

The means for obtaining the transition alumina-based hollow catalyst carrier of the present invention using the rewaterable alumina and other aggregate constituents as raw materials will be explained. For example, (1) the rewaterable alumina may be partially or completely A water-removed and/or water-containing substance coated with a rehydration inhibitor is mixed and kneaded with aggregate components other than rewaterable alumina, a binder, etc., as necessary, to form a plastic clay. The obtained clay is extruded by supplying it to an extrusion molding means equipped with a suitable pipe or multi-cell molding die, and then the molded body obtained is subjected to rewatering treatment, and then dried if necessary and activated by firing. Method or (11) Mix and knead re-waterable alumina and a non-aqueous substance that becomes liquid at temperatures below 100°C, with the addition of aggregate components other than re-waterable alumina, a binder, etc., as necessary, to create plastic clay. Then, the obtained clay is extruded by supplying it to a suitable extrusion molding means equipped with a pipe of arbitrary shape or a die for multi-cell molding, and then the molded body obtained is subjected to rewatering treatment and then dried for a necessary period of time. However, a method of activating by firing, etc. can be applied.

Conventionally, when extrusion molding is performed using ceramic powder as a raw material, water and/or water are used to impart plasticity to the ceramic clay.
Alternatively, a water-containing substance is used, but water and/or
Or, when a water-containing substance comes into contact with the alumina, a rewatering reaction occurs in alumina, which hardens with heat in the extruder and becomes unmoldable, thereby obtaining the desired healthy catalyst support on the inner and outer walls, especially on the inner wall surface. Can not do it.

Therefore, when extruding the catalyst carrier of the present invention, as mentioned above, before mixing and kneading the rewaterable alumina with water or a water-containing substance together with other aggregate constituents, etc., the rewaterable alumina is mixed with the rewatering prevention agent. Otherwise, it is necessary to knead the material partially or completely with a liquid non-aqueous material without using water or a water-containing material during kneading to form a plastic clay for extrusion molding.

The rewatering prevention agent may be any agent that can prevent water and rewaterable alumina from causing a rewatering reaction during extrusion molding, making it impossible to mold. In the case of solid organic substances, the solubility in cold water at room temperature is approximately 2.
0% by weight or less, preferably about 10% by weight or less.

Further, in the case of organic substances that are liquid at room temperature, examples thereof include those whose mutual solubility in water at room temperature is at most 50 coefficients or less, preferably 25% or less.

More specifically, caproic acid, palmitic acid, oleic acid, glycolic acid, caprylic acid, stearic acid, salicylic acid, trimethylacetic acid, lauric acid, cerotic acid, cinnamic acid, malonic acid, myristic acid, sebacic acid, benzoic acid. ,
Fatty acids and their salts such as maleic anhydride and wax, or sulfonic acids, phosphoric acid substituted products thereof, alcohols such as t-butyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, cyclohexanol, menthol, cholesterin, and naphthol, Amines such as laurylamine, tetramethylenediamine, jetanolamine, diphenylamine, alkanes such as n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, aromatic compounds such as naphthalene, diphenyl, anthracene, starch, casein, Cellulose and its derivatives, natural polymer compounds such as alginate, synthetic polymer compounds such as polyethylene, polyvinyl alcohol, polyvinyl chloride, polypropylene, sodium polyacrylate, polybutadiene, isoprene rubber, urethane resin, liquid paraffin, soybean oil , paraffins such as white squeeze oil, light oil, and kerosene; carboxylic acids such as caprylic acid and pelargonic acid; and aromatic hydrocarbons such as benzene, toluene, xylene, and cumene.

These rehydration inhibitors are added and mixed in such a proportion that they can partially or completely cover the rewaterable alumina surface.
Coating methods include adding and mixing directly to the powder, or kneading to coat the powder, or if the rehydration inhibitor is a solid substance that is difficult to coat directly on the powder, an appropriate coating method such as alcohol or ether may be used. The anti-rehydration agent can be dissolved in a solvent in advance and then coated, or in the case of a liquid, it can be directly immersed in the anti-rehydration agent, or the liquid can be vaporized and coated on the powder surface. There are various methods such as

Of course, these may be used in combination.

The amount of rewatering inhibitor added depends on the particle size distribution and composition of the aggregate, the conditions of extrusion molding and subsequent rewatering treatment, but it is usually 0.01% to 30% by weight based on the rehydrating alumina. Used in the heavy hereditary range.

If the amount added is less than o or oi, the effect of preventing rewatering will not be sufficient, and it will harden due to heat during extrusion molding, making molding impossible, which is not preferable.

However, if the rewatering prevention agent also serves as a binder, which will be described later, the amount added can be increased up to the upper limit of the amount added of the binder.

The binder used as necessary in the extrusion molding of the hollow catalyst carrier of the present invention is not particularly limited as long as it is a known binder used in the production of alumina catalyst carriers. Examples include polyvinyl alcohol, starch, cellulose, and the like.

The amount of binder added depends on the composition of the aggregate that makes up the hollow structure,
Particle size, extrusion molding conditions, and rewatering treatment conditions Q are also affected and cannot be determined unambiguously, but usually 3
This is the range under 0 weight hereditary.

If the amount of binder is too large, distortion occurs in the molded product when the rewatering prevention agent disappears from the extruded product, resulting in poor dimensional stability and a decrease in strength.

If the rewatering prevention agent has a caking effect, it is of course possible to use it by adding only the amount lacking as a caking agent.

On the other hand, the total amount of binders and anti-rehydration agents should be at least 2.5 times the total weight of the aggregate. If the material has the effect of a binder, it is not necessary to add a binder, and if the non-aqueous substance does not act as a binder, it is necessary to add at least 1.5 times the binder. be.

After selecting and adjusting aggregate raw materials, binders, etc. as described above, if rewatering prevention treatment is performed, rewatering alumina coated with a rehydration inhibitor is used as a material for other aggregate components. A plastic adhesive is formed by kneading water or a water-containing substance together with a binder, etc., or, if rehydration prevention treatment is not performed, rewaterable alumina with its fine aggregate constituents, a binder, etc., and a non-aqueous substance. Soil and pear are used for extrusion molding.

Before supplying the plastic clay to an extrusion molding machine, it may be prepared by kneading aggregate and water or a water-containing substance, or a non-aqueous substance in advance, or an extrusion molding machine with a kneading function may be used. In this case, it is of course possible to carry out the kneading operation in an extruder.

The amount of water or non-aqueous substances added during molding is not necessarily the same depending on its function, but in the case of water it is generally in the range of about 20 to 70 times the aggregate component, and in the case of non-aqueous substances varies depending on the particle size distribution and composition of the aggregate constituents, extrusion molding and subsequent rewatering treatment conditions, but
It is used in the range of about 2 to 100 times the rehydratable alumina.

The term water-containing substance used here refers to an aqueous solution containing acids, alkalis, catalyst components, binders, and other various additives, while non-aqueous substances are liquid substances at temperatures below about 100°C. Suitable examples include alcohols with 1 to 4 carbon atoms such as methanol, ethanol, and propyl alcohol, hydrocarbons such as hexane and heptane, polyhydric alcohols such as ethylene glycol and glycerin, liquid paraffin, and soybean oil. , paraffins such as white squeeze oil, diesel oil, and kerosene, carboxylic acids such as caprylic acid and pelargonic acid, esters such as ethyl silicate and methyl acetate, benzene,
Aromatic hydrocarbons such as toluene, xylene, cumene, dioxane, and mixtures thereof may be mentioned.

A more preferable non-aqueous substance is a crosstalk temperature (room temperature + 10°
C) Non-aqueous substances such as dioxane, ethanol, propyl alcohol, ethylene glycol, glycerin, and white squeezed oil that are liquid in the following manner can be mentioned.

Although a mold release agent is not particularly required during extrusion molding,
Saturated fatty acids or salts thereof, more specifically stearic acid, calcium stearate, etc., may be added at the time of crosstalk.

The amount used is usually in the range of 0% to 5% by weight based on the aggregate.

As an extrusion molding means for molding the hollow catalyst carrier of the present invention, any molding machine capable of forming a pipe-like or multi-cell shape with a porosity of 3 or more, preferably 20 to 90, can be used. Although not particularly limited, for example, extrusion molding machines for multi-cell shaped bodies are described in U.S. Pat. Examples include those with dice.

In addition, in order to improve the contact time with processing gas etc. passing through the multi-cell catalyst carrier and each core of the catalyst, we have developed a multi-cell molded body (with fins extending toward the center of each core) attached to the thin wall portion forming the core. For example, JP-A-50-127
No. 886), a multi-cell molded body in which a thin wall in at least one direction is bent in the extrusion direction for the purpose of preventing cracking, distortion, etc. due to expansion and contraction of multi-cell constituent materials during drying and firing of the multi-cell molded body. (For example, Japanese Patent Application Laid-Open No. 51-565), furthermore, an extrusion molded product is produced in which a collar ring is attached to the thin wall constituting the outer periphery of the multi-cell molded product, or a thick outer periphery is formed using a die structure to improve impact strength. An extruder or the like that can be used can be used.

The outer shape and core shape of the hollow molded body are square, rectangular,
The geometric shape may be triangular, hexagonal or circular, and the number of cores, the thickness of the cells forming the core, the length of the molded body, the cross-sectional area of each core, and the pipe-like or multi-cell shape The total cross-sectional area of the core forming surface (outer shape) of the body may be arbitrarily determined depending on the purpose.

The reason why the porosity of the catalyst carrier of the present invention is limited to 3% or more is to distinguish it from conventionally known spherical or cylindrical activated alumina catalyst carriers. The hollow catalyst carrier of the present invention has extremely excellent properties such as a large specific surface area per unit weight and a small pressure loss during exhaust gas treatment.

Although extrusion molding has been mainly described as the method for obtaining the hollow catalyst carrier of the present invention, it can also be produced using injection molding or a transfer molding machine.

The hollow shaped body extruded in this manner is then subjected to rewatering treatment in order to increase the impact strength and mechanical strength of the final product, the catalyst carrier.

By rehydrating the hollow-shaped compact formed by using the rewaterable alumina of the present invention as an aggregate constituent, sufficient strength for practical use can be achieved without forming a ceramic bond by sintering. .

As the rewatering treatment method, any method commonly used in the production of activated alumina may be adopted, and generally the treatment is carried out at room temperature to 150°C, preferably at 80 to 100°C, for a sufficient period of time for rehydration.
or in water vapor at a temperature above room temperature, particularly preferably above 80°C.

When using an agent that is insoluble in water at the above temperatures as a rewatering prevention agent, for example, when polyvinyl chloride is used, it must be immersed in a solvent such as alcohol, ether, or ester to destroy or dissolve the coating layer. rehydrated with water contained in the extruded structure.

In addition, if a nonaqueous substance is used during extrusion molding and its solubility in water is 5 or more at room temperature, the water used for the water utilization reaction may be diluted with a hydrophilic solvent such as alcohol to reduce the activity of the water. Alternatively, a method of rehydration in steam is effective in terms of the shape retention of the product.

Rewatering generally takes place for 1 minute to 1 week.

The longer the rewatering time and the higher the temperature, the more solidification of the molded body progresses, resulting in a product with greater mechanical strength, so the higher the rewatering temperature, the shorter the rewatering time.

It is also possible to leave it in a closed container at room temperature and pressure for rehydration over a long period of time.

The molded product rehydrated in this way is then subjected to a known method such as natural drying, hot air drying, or vacuum drying to remove adhering moisture, and then heat-treated at a temperature of about 100 to 1100°C to remove the moisture inside the molded product. Removes moisture and activates.

A drying process after rewatering treatment is not essential.

That is, by slowing down the temperature distribution during firing, for example, it can be fired from room temperature to 300°C in 48 hours, and at 300°C.
It can also be carried out by firing at a temperature of 6 to 12 hours at temperatures above 1100°C.

If a combustible substance is mixed in the molded article during firing, heat treatment is performed at a temperature of about 250° C. or higher to eliminate the combustible substance.

When activation and removal of combustible substances are performed at the same time, for example, a compact containing a combustible substance is placed on a bed, and hot air or combustion gas at a predetermined temperature containing sufficient oxygen to burn the combustible substance is heated. This can be done by passing.

In the hollow catalyst carrier obtained by the above method, the crystal phase after firing activation is substantially composed of transition alumina such as γ-alumina, and the specific surface area is about 5 mj/g or more, furthermore, 10 m
g or more, the bulk density is 0.1 to t2g/=, and the pore volume is 0.
3 cml 9 or more, compressive strength is approximately 20 kg in the extrusion direction
/C1? L or more, and even more than 30 Yu/cIIL, it is possible to obtain a multi-cell catalyst carrier with a wall thickness of 1 mm or less, similar to the ceramic multi-cell catalyst carrier, and it has a lower wall thickness than the conventional ceramic hollow catalyst carrier. It is extremely superior in surface area and pore volume, and in addition, the mechanical strength such as compressive strength imparted to the hollow catalyst carrier of the present invention is about 1200 to 200% higher than that of conventional ceramic structures.
Unlike the strength imparted by ceramic bonding through high-temperature firing at 100 to 1100 degrees Celsius, strength is imparted based on the rewatering reaction, and activation is only imparted by firing at 100 to 1100 degrees Celsius, so the physical properties are Not only does it have an excellent specific surface area, but also the firing temperature is low, making it an ideal material for firing equipment.
Equipment maintenance costs and fuel costs are extremely low, and its industrial value is outstanding.

In the present invention, a hollow catalyst carrier suitable for a specific use can also be obtained by mixing a special substance into the aggregate constituting the extruded body or by impregnating the extruded body with a special substance.

For example, hollow catalyst carriers, such as automotive catalyst carriers, require extremely excellent heat resistance and impact resistance, as well as slowing down the transition from γ-alumina to α-alumina and requiring long-term high activity. In order to obtain an organosilicon compound, an organosilicon compound is mixed into the cell-constituting aggregate components, or an organosilicon compound is extruded into a molded product (before or after rewatering treatment).
One example is a method of supporting this.

The organosilicon compound contained or supported in the molded body is oxidized or thermally decomposed in the firing step for activating the extruded molded body, and becomes a hollow catalyst carrier having the above-mentioned performance.

The above organosilicon compound may be any organosilicon compound as long as it produces silicon dioxide through oxidation or thermal decomposition, but specific examples include acetoxytrimethylsilane, acetoxytriethylsilane, diacetoxydimethylsilane, and diacetoxydiethyl. Organoacetoxysilane such as silane, organoalkoxysilane such as methoxytriethylsilane, dimethoxydimethylsilane, organodisilane such as hexamethyldisilane, hexaethyldisilane, trimethylsilanol, dimethylphenylsilanol, triethylsilanol, diethylsilanol, triphenylsilanol, etc. Examples include organosilanol, organosilane carboxylic acid, organosylmethylene, organopolysiloxane, organohydrogenosilane, organopolysilane, silicon tetrachloride, and the like.

The amount of organosilicon compound supported in the molded body is generally 0.01 to 30% by weight when converted to 5in2 with respect to alumina, and 0.1 to 10% by weight hereditary, which is not economical if it exceeds the hereditary weight. On the other hand, if the weight is less than 0.01, the effect of improving heat resistance is small, which is not preferable.

It is not clear why the transition alumina-based catalyst carrier obtained by supporting an organosilicon compound exhibits little reduction in reactivity over time and has extremely excellent impact strength and heat resistance, but the reason is that the transition alumina catalyst carrier obtained by supporting an organosilicon compound exhibits excellent impact strength and heat resistance. Because silicon is extremely fine and highly reactive, silicon dioxide and activated alumina react under temperature conditions that do not cause the active alumina in the catalyst carrier to become pregelatinized, and alumina-silicon dioxide reactants are formed on the surface of the activated alumina. It is presumed that this effect is produced due to the formation of

Furthermore, after activation, the transition alumina-based catalyst carrier obtained by the method of the present invention is brought into contact with a mineral acid, washed with water, and then dried to obtain a highly active catalyst carrier with a large macropore volume. You can also do it.

As the mineral acid, for example, hydrochloric acid, nitric acid, and sulfuric acid are preferably used.

The concentration of the mineral acid aqueous solution used is not particularly limited, but preferably one having a concentration of 0.1N to 10N is used.

Contact between the transitional alumina catalyst carrier and the mineral acid is generally carried out by immersing the catalyst carrier in the mineral acid, and the treatment time is generally 10 minutes or more.

If the treatment time is 10 minutes or less, the effect of enlarging the macropore volume will not be significant.

Although the treatment temperature is not particularly limited, it is generally 10
Operationally, it is desirable to process at a temperature of 0° C. or lower.

In the present invention, the transition alumina-based hollow catalyst carrier can be formed by mixing the catalyst component into the constituent aggregate components to form a hollow catalyst, or the catalyst component can be supported on the hollow catalyst carrier by impregnation or spray treatment. You can also do that.

The catalyst components to be supported and/or contained vary depending on the application, but at least known combinations of activated alumina as a carrier and catalyst components can be used by replacing the carrier with the hollow catalyst of the present invention.

For example, Pt may be added to the extrusion-molded hollow catalyst carrier of the present invention.
A catalyst supporting or containing at least one of Ru, Rh, and Pd can be used for non-selective reduction of NOx in exhaust gas from various fixed sources, selective reduction of NOx by NH3, oxidation of CO1 hydrocarbons in automobile exhaust gas, etc. It is used for reducing NOx, deodorizing various industrial exhaust gases, etc., and contains Cu, Fe, Co,
A catalyst supporting or containing at least one of the oxides of NilMn and V can be used for selective reduction of NOx in exhaust gas, oxidation of CO1 hydrocarbons in automobile exhaust gas, NOx
It is used as a catalyst for reducing NO, deodorizing various industrial exhaust gases, and decomposing NO.
A catalyst that supports or contains at least one of the oxides of B, Ag, Ce1Sn, Re, and Ta can reduce NH4 in exhaust gas.
- It is used as a catalyst for selective reduction of NOx, oxidation of CO1 hydrocarbons in automobile exhaust gas, and reduction of NOx.

The method of impregnating or spraying these catalyst components onto a catalyst carrier may be carried out by a known method.On the other hand, when the catalyst component is incorporated into an extruded product, the rewaterable alumina is treated with a rewatering inhibitor or It may be added and mixed before treatment, before mixing and kneading with a non-aqueous substance, or at the time of crosstalk.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples.

Example 1 2 parts by weight of stearic acid was added to 100 parts by weight of activated alumina powder containing 30 parts by weight of ρ-alumina with an average particle size of about 6μ obtained by burning a gibbsite-type alumina aquarium, and 2 parts by weight of stearic acid was crushed with a crusher. After mixing for a period of time to coat the alumina surface with stearic acid, 5 parts by weight of methyl cellulose and 50 parts by weight of water were further added, and after kneading for 30 minutes in a mixer, the mixture was fed to a screw extruder with a wall thickness of 0.4 mm. Approximately 100mmX100mmX15 with a square core unit of 2mm on each side
A multi-cell molded body with 0 to J (porosity 69.4%) was obtained.

Next, this multi-cell molded body was subjected to a rehydration reaction in steam for 2 hours, and then heated at a heating rate of 100°C/hour to 70°C.
The temperature was raised to 0°C, and further baked at 700°C for 1 hour.

The multi-cell catalyst carrier thus obtained has a compressive strength of 6
0kg/Cr? L, specific surface area 150 cr? L/g, pore volume 0.6 cI7L/g, bulk density 0.37g/cr
? According to X-ray diffraction, the main component of the alumina constituting the multicell was γ-alumina.

Example 2 A powder consisting of 70 parts by weight of activated alumina powder containing 50 parts by weight of ρ-alumina with an average particle size of about 5 μm and 30 parts by weight of α-alumina powder with an average particle size of about 5 μm was mixed with 0.0% sodium alginate.
After adding 5 parts by weight and mixing with a crusher for 1 hour to coat the surface of the alumina powder with sodium alginate, further adding 10 parts by weight of methylcellulose and 40 parts by weight of water, and mixing with a crusher for 3 hours.
Kneaded for 0 minutes, fed to screw extruder, wall thickness 1mm
i o has a square core unit with a side of 4 mm.
A multi-cell molded body with QmmφX150mm1 and a porosity of 64 was obtained.

Next, this multi-cell molded body was placed in a closed chamber, and after a rehydration reaction was performed at room temperature for one week, the temperature was raised to 600°C at a temperature increase rate of 50°C/hour, and further baked at 600°C for 1 hour.

X-ray diffraction of the multi-cell catalyst carrier thus obtained revealed that the main component was γ-alumina and the compressive strength was 55 kg.
/ffl, specific surface area 160m/, 9, pore volume 0.45
i/g, and the bulk density was 0.5 g/i.

Example 3 Powder 1 consisting of 40 parts by weight of ρ-alumina, 40 parts by weight of X-alumina, and 20 parts by weight of α-alumina with an average particle size of about 5 μm
Add 1 part by weight of white squeezed oil to 00 parts by weight and mix for 1 hour in a crusher to coat the surface of the alumina powder with white squeezed oil, and then add 8 parts by weight of methylcellulose, 15 parts by weight of spodumene, and 60 parts by weight of water. In addition, after being mixed in a mixer for 30 minutes, it was fed to a screw extruder to form a 100mm x 100mil square core unit with a wall thickness of 0.3 mm and a side of 2 mm.
A multi-cell molded body having a size of 00 mm x 100 mm and a porosity of 75.6% was obtained.

Next, this multi-cell molded body was placed in warm water at 95°C for 2 hours.
After soaking for 40 minutes to rehydrate, dry with hot air at 80°C for 5 hours, and after drying, heat to 700°C at a heating rate of 100°C/hour.
The temperature was raised to 700° C. for 1 hour.

The multi-cell catalyst carrier obtained in this way has a compressive strength of 9
0kg/Cn! L, specific surface area 120 m'/g, pore volume 0.47 crit/El, bulk density 0.45 g/ff
When X-ray diffraction was performed on the multicell, it was found that the main component of the alumina constituting the multicell was γ-alumina.

Example 4 700% of alumina aqueous solution obtained by Bayer method
40 parts by weight of ethylene glycol and 5 parts by weight of methyl cellulose were added to 100 parts by weight of re-waterable alumina obtained by instantaneous calcining (about 10 seconds) with hot gas at ~800°C.
After kneading with a crusher, feed it to a screw type extruder and reduce the wall thickness to 0.
．． Approximately 100mm x 100mm x 150mr/Ll, with a honeycomb-shaped cross section of 4 ynm and 27n7JL on each side,
A multi-cell molded body with a porosity of 69.9% was obtained.

Next, this multi-cell molded body was rehydrated in steam for 2 days, then dried in a constant temperature bath at 80°C for 1 day and night, and heated at a heating rate of 50°C/hour to 300°C, and then at a heating rate of 100°C/hour. The temperature was raised to 600°C, and the mixture was further fired at 600°C for 5 hours.

The multi-cell catalyst carrier thus obtained has a compressive strength of 5
0kg/ffl, specific surface area 150 m”/&, M
The pore volume was 0.6 antl 9, the bulk density was o379/cA, and X-ray diffraction revealed that the main component of the alumina constituting the multicell was γ-alumina.

Example 5 Re-waterable alumina 10 produced by the same method as Example 4
50 parts by weight of cordierite, 10 parts by weight of starch, and 30 parts by weight of glycerin were added to 0 parts by weight, and after kneading with a crusher, the mixture was fed to a screw type extruder with a wall thickness of 0.4 mm and a side of 2 m11.
Approximately 100m1 x 100mm with L rectangular cross section
A multi-cell molded body having a size of 150 mm x 111 and a porosity of 69.9 was obtained.

Next, this multi-cell molded body was rehydrated in steam for 2 days, dried in a constant temperature bath at 80°C for 1 day and night, heated to 700°C at a heating rate of 100°C/hour, and further heated at 700°C for 1 hour.
Baked for an hour.

The multi-cell catalyst carrier thus obtained has a compressive strength of 5
0kg/crA, specific surface area 120m/g, pore volume 0.
At a bulk density of 35i/E11 of 0.4°4g/=, X-ray diffraction revealed that the main component of the alumina constituting the multicell was γ-alumina.

Example 6 A multi-cell molded body formed and rewatered in the same manner as in Example 1 was heated to 1100°C at a temperature increase rate of 100°C/hour, and further fired at 1100°C for 1 hour.

The multi-cell catalyst carrier thus obtained has a compressive strength of 5
0 kg/cril, specific surface area 20 m”/9, pore volume 0.4 critl 9, bulk density 0.45.9/i
According to X-ray diffraction, the alumina that makes up the multicell is θ-
Alumina was the main component.

Comparative Example 1 4.5 parts by weight of methyl cellulose and 25 parts by weight of water were added to 100 parts by weight of cordierite powder with an average particle size of 8 μm, mixed in a kneader for 30 minutes, and then mixed in an extrusion molding machine similar to that used in Example 1. After molding using the same material, it was dried, and then the temperature was raised to 1300°C at a rate of 100°C/hour, and baked at the same temperature for 5 hours.

The ceramic multi-cell catalyst carrier thus obtained had a compressive strength of 250 ky/i, a specific surface area of 0.2rn''7g, and a pore volume of 0.20c11t/y.

Comparative Example 2 5 parts by weight of methyl cellulose and 26 parts by weight of water were added to 100 parts by weight of mullite powder with an average particle size of 5 μm, mixed in a kneader for 30 minutes, and then molded using the same extruder as used in Example 1. , drying followed by heating at 145°C at a heating rate of 100°C/h.
The temperature was raised to 0°C and baked at the same temperature for 10 hours.

The multi-cell catalyst carrier obtained in this way has a compressive strength of 3
00 kg/i, specific surface area 0.3 cyrt/El, and pore volume 0.15 crrt/9.

Comparative Example 3 100 parts by weight of activated alumina powder containing 30 parts by weight of ρ-alumina with an average particle size of 6μ obtained by calcining gibbsite-type alumina hydrate and 10 parts by weight of crystalline cellulose were mixed. While adding 50 parts by weight of water, the mixture was molded into a sphere with a diameter of 3 mm using a dish-type granulator.

The spheres were then rehydrated in steam for 2 days, dried, and then heated to 700 °C at a heating rate of 100 °C/hour.
The temperature was raised to .degree. C. and baked at the same temperature for 1 hour.

The spherical activated alumina molded body thus obtained has a compressive strength of 10 kg, a specific surface area of 180 i/g, and a pore volume of 0.7.
critl & was used as a catalyst support for the comparative test in Example 7 later.

Comparative Example 4 0.5 parts by weight of stearic acid was added to 50 parts by weight of activated alumina powder similar to that used in Example 1 and 50 parts by weight of α-alumina powder with an average particle size of 5μ, and mixed for 2 hours using a crusher. After coating the alumina surface with stearic acid, 1.5 parts by weight of methyl cellulose and 35 parts by weight of water were added and kneaded for 30 minutes in a kneader, and then molding was attempted using the same extruder as in Example 1. , it was impossible to extrude.

When the above method was carried out using 45 parts by weight of water, extrusion was possible, but the resulting molded product had extremely poor shape retention.

Example 7 After 155 parts by weight of 205 was supported on the catalyst carriers obtained in Examples 1 to 6 and Comparative Examples 1 to 3 based on the carrier weight, this was charged into a reactor maintained at an inlet temperature of 350°C. , NOlooppm, NH3100 Sir, 0□12%, H
Synthesis gas consisting of 2O18,0 part and the balance N2 is shown in Table 1 ζ
The nitrogen removal rate and pressure drop were measured by introducing the gas at the space velocity shown above.

The results are shown in Table 1. As is clear from Table 1, it can be seen that the multi-cell catalyst carrier of the present invention has a significantly better denitrification rate than other multi-cell catalyst carriers, and has a smaller pressure loss than spherical activated alumina particles.

Claims (1)

[Claims] 1. A fired body formed integrally by extrusion molding using powder containing rewaterable alumina as a raw material, and activated by firing after rewatering treatment, the main component of which is composed of transitional alumina,
Porosity is 3 coefficient or more, specific surface area is 5 m''/g or more, bulk density is 0.1-1.2//i, pore volume is 0.3 crit.
A transitional alumina-based hollow catalyst carrier characterized by having at least one opening in the extrusion direction with a diameter of 9 or more.