JPS5926339B2 - Catalyst for gas purification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a catalyst for gas purification for preventing air pollution, and particularly for cleaning harmful substances, oil smoke, etc. generated from various household combustion appliances and cooking appliances using oil, gas, briquettes, etc. as fuel. This invention relates to a catalyst body for purifying exhaust gas including odors.

The composition of exhaust gas from this type of household appliances is not uniform; for example, the main components of exhaust gas are unburned carbon monoxide and hydrocarbons, especially olefin hydrocarbons, in combustion appliances; - Mainly fatty acid hydrocarbons and aldehydes.

More specifically, the temperature of the catalyst body of various household combustion appliances is 600° C. or less (maximum temperature 700° C. or less) depending on the preferred installation position of the catalyst body.

In view of the above, the present invention provides a nicum-like catalyst body with excellent spalling resistance at a maximum temperature of 700°C.

Recently, with the spread of aluminum sashes, houses have become more tightly sealed, and as apartments and condominiums have become more high-rise, it has become difficult to ventilate indoor air in natural conditions. There is.

Under these circumstances, there is a strong desire for safety of household combustion appliances and for smokeless and odorless exhaust gas during cooking.

The purpose of the present invention is to: When using household combustion equipment,
We provide a catalyst body that improves the safety and comfort of using the cooker not only during normal use but also during abnormal use.
The present invention provides a catalyst body for oxidizing and purifying the oil smoke and odor of exhaust gas.

Furthermore, technological innovations have been made in household combustion equipment to provide high performance and low cost.

Due to such progress and marketability, a low-cost catalyst is essential, and the present invention provides a high-performance catalyst that is inexpensive and easy to manufacture.

Conventionally, seeded catalysts have been studied and industrialized as catalysts that can meet such purposes.

The main catalysts are noble metal catalysts and metal oxide catalysts.

It has been said that platinum, palladium or platinum black catalysts are particularly suitable as noble metal catalysts.

However, conventional platinum catalysts are expensive, and while metal oxide catalysts are cheaper, they are still too expensive for use in household combustion appliances.

It goes without saying that platinum catalysts are expensive, not only because the platinum itself is expensive, but also because the alumina molded bodies, glass fibers, etc. used as supports are expensive, and the manufacturing method (pretreatment) is complicated. This is due to the complexity of the method and post-processing.

Furthermore, it is difficult to impregnate the catalyst into the carrier, making it difficult to obtain a homogeneous product, and the wear resistance due to vibration is weak, the spalling resistance is poor especially at high temperatures, and the life of the catalyst is short. there were.

The catalyst carrier is not limited to alumina, but may include heat-resistant, chemically inert, and porous zircon, Schleit sillimanite, and magnesium silicate, as described in Japanese Patent Publication No. 47-50980. , aluminosilicate, etc.

However, the mainstream of materials in practical use are those whose main component is alumina.

Recently, carriers using porous metals such as foamed metals have also been commercialized.

Materials used as carriers can be roughly classified into two types: ceramic carriers and metal carriers, and there are various proposals for manufacturing methods for these carriers.

However, each of these catalysts has advantages and disadvantages.
The catalyst obtained by either method is expensive and requires further improvement before it can be applied to household combustion equipment.

The present invention eliminates the above-mentioned conventional drawbacks and provides a high surface area catalyst that is inexpensive and has excellent catalytic activity, spalling resistance, and abrasion resistance.

That is, the present invention uses a molded body containing alumina cement as a main component as a carrier, and contains alumina cement in the carrier composition, granular base aggregate to improve spalling resistance, and powder to increase the surface area of the carrier. Mix with aggregate,
Furthermore, it is characterized in that a metal or metal oxide catalyst is supported on a non-sintered bicam-shaped carrier.

The catalyst bodies previously proposed by the present inventors include A: a lime aluminate-manganese oxide catalyst; B: a lime aluminate-manganese oxide-heat-resistant aggregate catalyst; and C: a catalyst supported on a carrier containing alumina cement. These catalysts can be roughly divided into three types.

The performance of catalysts A and B differs significantly depending on the concentration of poisonous substances in the exhaust gas (particularly SO2 gas).

In other words, S at a relatively low concentration (less than 10 ppm as S02), such as in oil stoves that burn kerosene.
Compared to 02, it has excellent exhaust gas (CO, HC) purification performance, but it has been found that the exhaust gas purification performance with SO2 concentration of 50 ppm or more is significantly degraded.

On the other hand, as mentioned above, a C catalyst has been proposed for purifying exhaust gas containing a high concentration of SO2, such as briquette combustion exhaust gas.

The present invention is an improved version of this C catalyst, which further improves low-temperature activity, provides a catalyst with an excellent catalyst life, and limits the composition ratio of the carrier composition of the catalyst.

The carrier composition of the present invention uses alumina cement as an inorganic binder, and a granular base aggregate selected from the group of silica-based, alumina-based, and silica-alumina-based aggregates, and the granular base aggregate is pulverized. powder aggregate such as cordierite, zeolite, calcium carbonate, magnesium carbonate, etc., preferably porous powder aggregate (specific surface area 5 m/g
above), and is a further limited configuration of C.

The catalyst of the present invention relates to a non-sintered, nicum-like catalyst that is inexpensive and has excellent catalytic activity, heat resistance, wear resistance, and especially spalling resistance.

The main component of the catalyst carrier used in the present invention is alumina cement, which is distinguished from Portland cement.

Alumina cement is generally expressed as mAl2O3・ncaO, and Portland cement is expressed as rr/SiO2・
It is represented by n'caO.

Portland cement is in high demand and is inexpensive, but it has drawbacks such as heat resistance, spalling resistance, and slow hardening speed, and is also susceptible to attack by sulfate ions.

On the other hand, alumina cement has high heat resistance and a fast curing speed, and can be said to be a preferable cement from the viewpoint of catalyst production.

The composition of alumina cement is as described above, and when the lime content exceeds 40% by weight, the mechanical strength of the support increases, but the heat resistance decreases and it reacts with heavy metal oxides at high temperatures, such as 650°C. Above this level, manganese oxides generate CaMn204, etc., leading to thermal destruction of the catalyst.

On the other hand, if the lime content is low, heat resistance improves, but mechanical strength decreases, curing time during molding becomes longer, and productivity also deteriorates.

Furthermore, when the alumina content is less than 35% by weight, the heat resistance decreases.

On the other hand, as the alumina content increases, heat resistance improves.

When the mixed iron oxide content exceeds 20% by weight, the mechanical strength during heating decreases and the heat resistance decreases.

This iron oxide has a catalytic ability to purify gas, for example, purify carbon monoxide, at a temperature of about 300° C. or lower.

In order to exhibit such a promoter effect, it is preferable to contain iron oxide in an amount of 2% by weight or more.

The preferred composition of alumina cement is lime content of 15 to 40.
% by weight, especially 30-40% by weight, mialumina 35-80% by weight, especially 40-60% by weight, iron oxide 0.3-20% by weight, especially 2-10% by weight.

Portland cement is an example of this type of cement material, but it cannot withstand temperatures of 300°C or higher and is not suitable for the purpose of purifying exhaust gas from domestic combustion appliances where the catalyst temperature is about 300°C or higher.

Although alumina cement can withstand temperatures of 300°C or higher, it is preferable to use high alumina cement to withstand temperatures of about 700°C or higher.

Next, granular base aggregates include silica base aggregate, silica alumina base aggregate, and alumina base aggregate, and mineral phases include silicate minerals, mullite, corundum, sillimanite, β-alumina, and It is preferable to use magnesia, chromium, dolomite, magkuro, and chromag-based materials.

Also, depending on the operating temperature of the catalyst,
In C), a general granular base aggregate is used, and the high temperature side (700°
C or higher), it is preferable to use a heat-resistant granular base aggregate.

More specifically, examples of the silica-based aggregate include silica stone.

These base aggregates have SiO2 as a main component.

As silica-alumina base aggregate, chamotte, waxite,
There are high aluminas, etc., and 5iO2-A1203 is the main component.

As alumina base aggregate, α-A■203, β-A12
03, γ-Al Oβ-A1203, etc.

More commonly used main mineral phases include silicate minerals, mullite, corundum, silimainite, and β-alumina.

These base aggregates can be crushed to a certain extent, or base aggregates such as commercially available conical silica sand, alumina, and chamotte can be used.Generally, it is best to use commercially available silica sand or chamotte. It's convenient.

Furthermore, magnesia, chromium, dolomite, magcro, and chromag base aggregates can also be used, but these are mainly used at extremely high temperatures (1300°C or higher) and are not suitable for obtaining inexpensive catalyst supports. It's the economy.

In general, it is sufficient that the material has excellent spalling resistance at temperatures up to about 1000'C, and a silica-based base aggregate is sufficient.

Furthermore, for temperatures up to about 600° C., it is convenient to use ordinary sand, beach sand, etc., which are inexpensive among silica-based base aggregates.

Next, the particle size of the granular base aggregate will be explained.

The granular aggregate used in the present invention has a particle size of 200 mesh or more, preferably 10 to 200 mesh, of 90% by weight or more.

This is because the nicum-like carrier has a larger volume than the pellet type, and spalling resistance is particularly important, and it is possible to reduce expansion and contraction of the carrier and increase mechanical strength.

...The manufacturing method of the nicum-like carrier is the method previously proposed by the present inventors in which a slurry of alumina cement and aggregate is injected into a silicone rubber master mold to obtain a molded body, and the pressure molding method. etc., it can be created.

The apparent density (f/i) of the nicum-like carrier thus produced differs depending on the composition and pressurization conditions, and the higher the apparent density, the greater the mechanical strength.

For example, when the composition ratio is the same, the rougher (larger) the grain size of the granular base aggregate, the higher the apparent density and the higher the mechanical strength.

The particle size of the granular base aggregate used in the present invention is JIS-G5901
(1974) standard silica sand for molding was used.

As mentioned above, the preferred particle size is 10 to 200 mesh (1
680~74μ)...JIS standard (G5
901), the range of No. 14 to No. 150 is good.

When the number of meshes exceeds 10, the aggregate in the honeycomb-shaped carrier becomes uneven, and furthermore, it is necessary to increase the wall thickness between the pores of the honeycomb-shaped carrier, which is one of the special features of the honeycomb-shaped carrier. The ventilation resistance (small opening area) for exhaust gas, etc. increases (in the case of nicum-shaped carriers with the same outer diameter), which has a thermal effect on household combustion equipment (particularly, the combustion balance is disrupted).

However, it can be easily assumed that even 10 Metsu 7 Yu or more can be used depending on the purpose of use.

On the other hand, if it is less than 200 mesh, it is resistant to spots at high temperatures.
Since the IJ song (mechanical strength at high temperatures) deteriorates and cracks occur, the anti-spalling performance at high temperatures, which is the objective of the present invention, cannot be satisfied.

The following table 1 shows an outer diameter of 115 mm, a thickness of 10 mm, and a hole diameter of 3.
A silicone rubber mold with a diameter of 2 mm and 559 holes for making a honeycomb-like carrier was filled with alumina cement as composition A. *130% by weight, JIS standards No. 10, 14, and 28 as granular base aggregate.
70% by weight of silica sand with particle sizes of No. 1, No. 65, No. 100, No. 150, and No. 200, and add enough water for molding to form a slurry. It is obtained by injecting a material, first curing (solidifying to the strength necessary to release from the mold), and after releasing from the mold, second curing and drying.

Five such honeycomb-shaped carriers were prepared and heated at 500°C.
The results of baking at 700°C for 2 hours and examining the spalling resistance (occurrence of cranks) are shown.

As detailed in Table 1, at 500°C, fine particle size 20
When No. 0 was used, one out of five cracks occurred.

However, at 700°C, 4 out of 5 cracks occurred.

In the present invention, "cracks" refer to clearly large cracks,
Parts with good mechanical strength were considered to be non-defective if they had small cracks overall (those with little effect on mechanical strength).

This Table 1 shows composition A (granular aggregate near alumina cement to 3 by weight), but the mixing ratio of alumina cement to granular base aggregate is (2:8), (4:6), (5
The results of similarly changing the particle size of the granular base aggregate for 25), (6:4), and (7:3) are not shown, but the results are similar to those shown in Table 1 when heated at 700℃ for 2 hours. Similar results were obtained when the particles were heat treated as long as the grain size was 150 or more.

Please note that for those with a composition of (7:3), it is necessary to use a grain size of 48 or more, and for those with a fine grain size, cracks (3:3) must be used.
) occurred.

Similar results were obtained for the pressure molded product (0.5 kL'cry).

From the above, the grain size of the granular base aggregate used for non-sintered honeycomb type carriers should be in the range of 10 to 200 mesh (JIS standard No. IO to No. 150) because it has excellent spalling resistance (cracking) at high temperatures. There is.

However, since 2 to 10% by weight of fine powder (coarse powder) is mixed in JIS standards No. 10 to 150, the particle size range of 10 mesh to 200 mesh is 90% by weight.
The above is the preferred particle size distribution of the silica sand used in the present invention.

Next, as the powder aggregate, silica-based, silica-alumina-based, alumina-based aggregate, etc., similar to the granular base aggregate, can be used.

Furthermore, in addition to these aggregates, porous powder aggregates such as zeolite and calcium carbonate can also be used.

The particle size of the powder aggregate of the present invention is 200 mesh or less.

Next, the present invention will be explained in more detail with reference to Examples.

Table 2 shows the relationship between the composition of the honeycomb carrier and the spalling resistance at a constant temperature, and this relationship is plotted in a ternary composition diagram of alumina cement - granular base aggregate - powder aggregate. What I did was Figure 1, Figure 2, and Figure 3.
It is a diagram.

FIG. 1 shows the claims of the present invention, and FIG. 2 shows the carrier 7.
Figure 3 shows the spalling resistance (cracking) when heated at 00°C for 2 hours, and Figure 3 shows the spalling resistance (mechanical strength).

In these figures and tables, cracks...
The mark ○ indicates that there was no cracking among the 5 samples, the mark ] indicates that cracks occurred in 2 or less of the 5 samples, and the mark . indicates that cracks occurred in 3 or more of the 5 samples.

Mechanical strength (transverse rupture strength)・・・○ mark indicates transverse rupture strength of 30 kg/ca or more, ] mark indicates 20 to 30 kg/cd
,・marks represent 20 to 9/crj, and the following.

However, as a result of various studies conducted by the present inventors regarding the transverse rupture strength, it has been found that no practical problem will arise as long as the transverse rupture strength of the honeycomb-shaped carrier is 30X+/i or more (the lowest transverse rupture strength is 20 kl?/cT).
L) has been confirmed.

In practical use, the present inventors conducted various studies on the correlation between transverse rupture strength and impact, and found that a honeycomb-shaped carrier (outer diameter 11.5 mm)
Figure 4 shows the correlation between cracking (destruction) of the carrier and transverse rupture strength when the carrier was dropped from a height of 30 CrIL.

The reason for setting the height to 30CrL is that as a result of drop tests on commercially available honeycomb carriers (alumina or cordierite), depending on the type of honeycomb structure, >k20~30CrIL
As a result of a drop test from a height of
The present inventors set the falling distance to 30 CrIl.

The honeycomb-shaped carrier used here was alumina cement (mainly containing 47.1% by weight of alumina, 36.0% by weight of lime, and 9.5% by weight of iron oxide, with the remainder being silicon oxide, titanium oxide, etc.) ), silica sand (JIS Standard No. 100) as the granular base aggregate, and alumina (
Alpha type) in the ratio shown in Table 2, and add enough water to mold it to form a mold with an outer diameter of 115 mm.
1. The slurry was poured into a silicone rubber mold for a carrier having a thickness of 10 mrrt, a hole diameter of 3.2 mm, and 559 holes, and after primary curing, the mold was released, secondary curing was performed in boiling water, and the resulting product was dried. It is something that

Looking at these results, the difference in spalling resistance characteristics at high temperatures (700° C.) is clearly evident.

That is, when there is less alumina cement, there will be less cracking even if the granular base aggregate is less (the powder aggregate is more).

However, if there is a large amount of alumina cement (60% by weight)
(above), the effect of adding granular base aggregate was small and cracks occurred.

A preferred composition is a range consisting of points B, J, F, G, H, and I.

From the above, when looking at the cracking and transverse rupture strength spalling resistance characteristics at the maximum operating temperature of 700°C for household combustion equipment, the following points B, C, and D in the three-component system composition diagram in Figure 1.
, E, F, G, H, and I.

Regarding the favorable tendency of spalling resistance, alumina cement has a lower spalling resistance and cracking.
The thicker the granular aggregate and the smaller the powder aggregate, the higher the strength, while the mechanical strength (transverse rupture strength) is higher for alumina cement, higher for the granular aggregate, and lower for the powder aggregate.

Conventionally, many catalyst carrier materials have undergone a sintering process during molding, and in order to compensate for the low surface area, there are many examples in which activated alumina, etc., which is active and has a large surface area, is supported on the surface. The characteristics are that the carrier has strength even without sintering as described above, and has a high surface area.

Another feature of the present invention is that the catalyst carrier is heated at a high temperature (300'
C or higher) and have catalytic ability.

The features of the present invention are as follows.

(1) Since we used alumina cement, granular aggregate, and powdered aggregate as a catalyst carrier, the price was low, and the alumina cement itself could be used without going through processes such as sintering. It can be molded into a desired shape using the bonding force of

(2) The catalyst carrier itself has the ability to purify carbon monoxide at high temperatures (300 to 500°C), and also has the ability to adsorb and remove acidic gases such as sulfur dioxide due to the lime content in the alumina cement.

(3) The surface hardness of the catalyst carrier is moderate and the surface area is quite large, so that it plays a sufficient role as a carrier.

(4) Efficiency of adhesion of catalyst to catalyst carrier (including adhesion strength)
is large.

That is, the wetting phenomenon of the catalyst salt such as water or alcohol with the solvent is large, and the catalyst can be supported in an effective homogeneous dispersion.

(5) Compared to commercially available alumina supports, it has lower abrasion strength and less attrition loss during use (and is stable as a catalyst for a long period of time).

(6) Since the catalyst can be reactivated by the catalyst carrier, a catalyst body with high performance and long life can be obtained with an extremely small amount of catalyst supported.

For example, if a platinum group metal catalyst is inactivated, such as by sulfur dioxide gas, CaO-H2O in alumina cement
is reactivated as follows.

Pt-8O+Ca0-HO→Pt+CaSO4・H20
2 Also, in the case of metal oxide MOx, it is reactivated as follows.

(7) The feature of using alumina cement as a catalyst carrier is that there is no need to sinter the molded body and it can be molded at room temperature, and compared to sintered bodies, the cement particles are finer and the surface area is larger. be.

Furthermore, the sintered body undergoes thermal shrinkage of about 10 to 30% compared to the original mold, making it difficult to maintain uniform mold precision of the molded body (carrier).

On the other hand, when using alumina cement (it is an unsintered body)
It is possible to reduce the mold accuracy to 2% or less.

(8) Conventional sintered bodies have sintered surfaces and have a small surface area.

Therefore, performance cannot be obtained unless a large amount of catalyst is deposited, but since the molded body of the present invention is unsintered,
The carrier surface is an aggregate of fine particles and has a large surface area.
Since only a small amount of catalyst is required and it can be homogeneously dispersed, a high-performance catalyst can be obtained even when a small amount of catalyst is supported.

(9) For use in alumina cement as a catalyst carrier,
A part of the solution containing the noble metal salt is made alkaline by a substance that dissolves in water (lime in alumina cement).
For example, P t c l 6□→P t c 16 (O
H)) Therefore, it is generated near the surface of the carrier and does not reach deep into the pores of the carrier.

Therefore, the concentration distribution of the catalytic metal is concentrated on the surface of the carrier and does not diffuse into the interior of the carrier.

Therefore, the catalytic metal is uniformly dispersed, and the amount of catalytic metal supported is only required on the surface (which is smaller than the amount supported in the past).

The catalyst body of the present invention is mainly used for the purpose of purifying exhaust gas from household combustion appliances and cookers, and in particular, 70%
Although it is preferable to use it at a relatively low temperature of 0° C. or lower, its uses are not limited to those mentioned above, and it is also effective for oxidative purification of exhaust gas from various plants.

Furthermore, it is not only effective for carbon monoxide and hydrocarbons, but also for adsorption and removal of sulfur dioxide, for converting NO into NO2 for nitrogen oxide removal equipment, or for NO and CO.
, NO, and NH3 (platinum group catalyst).

Next, the method of supporting the catalyst will be explained.

The supporting methods mainly include coprecipitation, deposition, impregnation, and coating methods, and the impregnation method is used for honeycomb-shaped platinum catalysts using alumina as a carrier.

Although this impregnation method is relatively simple to manufacture, it is subject to restrictions on the amount of catalyst supported, and may cause abrasion of the surface of the carrier, reducing the surface area and pores, resulting in low activity. It has the following disadvantages.

In the examples of the present invention, an impregnation method and a coating method were mainly adopted.

The next supported catalyst is mainly a platinum group metal, including platinum, palladium, ruthenium, rhodium, and iridium, and chlorides are preferred as their salts.

Tetrachloroplatinic acid H2Ptel, i, hexachloroplatinic acid H2P j c 16, platinum diaminocinitrite Pt(MH3)2(NO2)2, palladium chloride P
Typical examples include dcl2, ruthenium chloride Rucl3, and rhodium chloride.

These metal salts are used after being dissolved in a solvent such as water or alcohol.

The concentration varies depending on the amount deposited and the supporting method, but if the solution is too concentrated, the dispersibility of the catalyst powder will be poor, so determine the optimal concentration depending on the purpose of use, shape, etc.

Especially when platinum group metals are used, compared to conventional platinum catalysts,
When the amount of platinum supported is 0.001 to 0.1% by weight, a catalyst body with high performance in both initial performance and lifetime performance can be obtained.

In other words, conventional platinum catalysts use carriers such as alumina and cordierite, and the amount of platinum supported is 0.5 to 0.1% by weight.When the amount of platinum supported is less than 0.1% by weight, the life performance is particularly deteriorated. is large, and the amount supported is common knowledge.

On the other hand, when the catalyst carrier of the present invention is used, high performance can be achieved even if the amount of platinum supported is minute.

As described above, when the catalyst carrier of the present invention is used, a high-performance catalyst body can be obtained in which only a small amount of platinum or the like is supported.

This is because part of the lime aluminate in the carrier absorbs water, A1203nCaO is partially dissolved, and part of CaO is liberated, and the solution becomes alkaline.

On the other hand, the raw materials for precious metal catalysts are mostly chlorides.
RuCl RhCl3, PdCl2, H2PtCl4
, 1 H2PtCl6.

For example, in the case of chloroplatinic acid, when dissolved in water, PtCl
A part of the 6”-ion (Cab) in the carrier is eluted,
Since it exhibits alkalinity, it forms PtC16(OH).

This salt PtC16(OH) is generated near the surface of the carrier,
It does not reach deep into the pores.

Therefore, the concentration distribution of the catalyst metal of the present invention is concentrated on the surface and does not diffuse into the interior of the carrier.

That is, as described above, the catalytic metal ions become hydroxides on the surface of the carrier and adhere as they are.

Furthermore, since the carrier is alkaline, the catalyst metal cations and a portion of the carrier surface form a compound, which is firmly attached to the carrier.

In this way, since it is possible to support only the surface layer, a high-performance catalyst can be obtained even if the amount supported is very small.

In addition, iron group elements iron and cobalt, Nickenope chromium group elements chromium and molybdenum, carbon group elements tin and lead, manganese group elements manganese, copper group elements copper and silver, rare earth elements lanthanum, and zinc group elements. Oxides such as zinc, cadmium, and vanadium of vanadium group elements can also be supported.

Among these, Pt, Pd, Mn,
Metals or oxides selected from Fe, Cu, and Ag are preferred.

There is a strong relationship between the amount of supported catalyst and performance, and normally the larger the supported amount, the better the performance, but if it is too much, problems such as catalyst falling off and catalyst dispersion may occur.

Furthermore, in addition to the catalyst amount, by supporting two or more types of various metals and metal oxides, it is also possible to improve the purpose of use, shape, low-temperature activity, life span, etc.**.

Figure 5 shows alumina cement 5 with various compositions shown in Table 3.
0% by weight and 50% by weight of silica sand (No. 100) was molded into the same pellets as above and heat-treated at 350°C for 1 hour. are at 400°C and 600°C.

Note that the conditions for measuring the purification rate are the same as in Example 1, which will be described later.

As is clear from the figure, when the iron oxide content in the catalyst carrier (alumina cement) is high, the carbon monoxide purification ability is poor.

Figure 6 shows pellets (A) consisting of 50 parts by weight of alumina cement and 50 parts by weight of silica sand (No. 7) having the composition shown in Table 3, and pellets (B) consisting of commercially available α-alumina.
This is a comparison of the carbon monoxide purification rate of samples heat-treated at a temperature of 1 hour at a temperature of °C.

As is clear from the figure, the catalyst carrier of the present invention has considerable catalytic ability at high temperatures, but commercially available catalyst carriers have almost no purifying ability even at high temperatures.

The present invention will be explained below with reference to Examples.

Example 1 An alumina cement consisting of 50 parts by weight of the composition shown in Table 3 and 50 parts by weight of silica sand (JIS Standard No. 100), diameter 200mm, thickness 15, dragon hole diameter 3.5mm, number of holes 12
A honeycomb-shaped carrier consisting of 00 pieces was prepared, and 1
The product subjected to heat treatment for a period of time was used as a catalyst carrier.

1 of hexachloroplatinic acid? /l of the aqueous solution dissolved at a ratio of 0.001.0.
01.0 and 05.0.1% by weight on both sides of the carrier, dried at 80°C for 1 hour, and then heat-treated at 500°C for 1 hour in an electric furnace.

The amount of catalyst supported in this way was 0.001.0, 01.0.0
5. Let the catalyst bodies of 0.1% by weight be a, b, c, and d, respectively.

In addition, 25 parts by weight of alumina cement having the composition shown in Table 3 2 and γ
- A catalyst obtained by molding a mixture with 275 parts by weight of Mno to the same diameter is designated as e.

These catalyst bodies were loaded into a stainless steel tube catalyst tank, and air containing about 200 ppm of carbon monoxide CO was pumped at a space velocity of 10.
The CO purification rate was determined by passing through the catalyst for 000 hr' and measuring the CO concentration on the inlet and outlet sides.

The results are shown in FIG. The present invention a = d has improved activity at low temperatures compared to the manganese oxide catalyst e.

Example 2 A disc-shaped carrier with a diameter of 2007nrIL1 and a thickness of 15mm, consisting of 50 parts by weight of alumina cement and 50 parts by weight of silica sand (No. 7) having the composition shown in Table 3, Table 2, and having 1200 holes in the thickness direction. was molded and heat treated at 300°C for 1 hour.

An aqueous solution of chlorides of various platinum group metals was applied to the upper and lower surfaces of this carrier, and heat treated at 500° C. for 1 hour.

The CO purification rate of the catalyst thus obtained was as shown in Table 4.

Example 3 After thoroughly mixing 25 parts by weight of alumina cement having the composition shown in the third table, 25 parts by weight of silica sand (No. 48), and 50 parts by weight of γ-alumina powder, 3 parts by weight of water and 1 part by weight of ethyl alcohol were added. A mixed solution was added to form a slurry, which was injection molded into a silicone rubber mold, hard molded after hardening, and completely cured in warm water.

After drying, this was heat-treated at 300°C for 1 hour.

This carrier had the same shape as the carrier in Example 1, and various catalysts were supported on it, and it was installed in the exhaust gas passage of an oil hot air fan to measure the purification rate of CO in the exhaust gas] Ice.

Note that the catalyst was installed in two stages.

50 to 100 pp of CO in exhaust gas, 2 to 100 pp of CO
It contained 5 ppm.

The temperature at the center of the lower catalyst was 600±20°C.

The above measurement results are shown in Table 5.

Moreover, the results of the life test for some of the products are shown in FIG.

In Table 5, Sample 1 uses α-alumina as a carrier.

Regarding the sample, copper oxide was supported and then platinum was supported, but other composite catalysts were supported at the same time using a mixed solution of catalyst salts.

As is clear from FIG. 8, even when the hot air blower was continuously burned for 1000 hours, there was little deterioration in the lifespan of the platinum-based contact.

However, the combustion was stopped for one week at 400 hours and 800 hours, respectively.

The platinum-based catalyst does not have a catalyst recovery (reactivation) effect, but this is because the catalyst does not deteriorate.

On the other hand, a manganese/copper-based catalyst has a recovery effect of about 10%, but the manganese/copper-based catalyst supported on α-A1203 of 1
The copper-based catalyst deteriorated significantly, and the catalyst did not recover even after one week of suspension.

In addition, manganese, copper,
It is also possible to add oxides such as nickel, iron, vanadium, cobalt, lead, silver, chromium, etc. in an amount of 50 parts or less, depending on the purpose and use.

Furthermore, in order to improve the spalling resistance, a fibrous inorganic material such as asbestos, glass fiber, etc. is added to the carrier composition 100.
It is also possible to add at a ratio of 10 parts by weight or less to parts by weight.

[Brief explanation of drawings]

FIG. 1 shows the three-component composition of the present invention, and the second
Figure 3 shows the spalling resistance when the carrier of the present invention is heated to 700°C, Figure 4 shows the relationship between transverse rupture strength and cracking in the carrier drop test, and Figure 5 shows the relationship between transverse rupture strength and cracking in the carrier drop test. Figure 6 shows the relationship between the CO purification rate of a support made of alumina cement and silica sand and the iron oxide in the alumina cement. Figure 6 shows the CO purification rate of the support. Figure 7 shows the CO purification rate of various catalysts. The figure shown in FIG. 8 is a diagram comparing the life of a catalyst using an oil hot air fan.

Claims (1)

[Scope of Claims] 1. Alumina cement as an inorganic binder, and at least one particle size 10 selected from the group consisting of silica-based, alumina-based, and silica-alumina-based aggregates mixed in the binder.
It consists of granular base aggregate of ~200 mesh and powdered aggregate with a particle size of 200 mesh or less obtained by pulverizing the base aggregate, and the amount of alumina cement, the amount of granular base pipe material, and the amount of powder aggregate are shown in Figure 1. In the ternary composition diagram shown, B, C, D, E,
F. A gas characterized by being composed of a non-sintered honeycomb-shaped carrier within the range surrounded by lines connecting G, H, and I, and a catalyst made of a metal or metal oxide supported on this carrier. Catalyst for purification.