JPS5944897B2 - Catalyst for exhaust gas purification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst body for exhaust gas purification, and is a catalyst for cleaning carbon monoxide, various hydrocarbons, sulfur dioxide gas, nitrogen oxide, etc. discharged from various combustion devices, or from cooking equipment, etc., which causes bad odors. It oxidizes and purifies oil smoke such as fatty acids, aldehydes, and amines.

In recent years, there has been a demand for the removal of this type of exhaust gas not only from the perspective of preventing air pollution, but also from the perspective of purifying indoor air as houses become taller and more airtight.

Despite the desire to purify a wide variety of gases, conventional catalysts mainly consist of platinum,
There is only a fobcalide catalyst based on metal oxides.

Among these, the most popular oxidation catalyst at present is a platinum-based catalyst in which platinum is supported using an alumina-based heat-resistant material as a carrier.

Although platinum catalysts have various advantages over metal oxides, they do not have superior oxidation performance for all gases, and metal oxide catalysts may actually be better for certain hydrocarbons. be.

Another major drawback of platinum catalysts is that they are very expensive.

Platinum catalysts are expensive because, of course, the platinum itself is expensive, but also because the molded carrier itself is expensive, and the manufacturing method for making the platinum carrier is complicated. There is.

In the future, as air pollution prevention, indoor air purification, and environmental purification become necessary, conventional catalysts will no longer be able to meet these demands, and new catalyst bodies are expected.

The present invention provides a catalyst that meets these requirements, which combines the excellent performance of the above-mentioned metal oxides and the excellent performance of platinum-based catalysts, and is also less expensive than conventional platinum catalysts. A catalyst body 4 having the following characteristics is provided.

The feature of the present invention is firstly the catalyst carrier.

The catalyst carrier consists of lime aluminate, metal oxide, and composite oxide as essential components.

Furthermore, it is also possible to strengthen the molded body by adding a heat-resistant base aggregate if necessary.

Heat-resistant base aggregates include inorganic compounds such as silica sand, alumina, and zeolite, as well as alkali-resistant glass fibers.
Details will be described later.

In constituting a catalyst body, the catalyst carrier supporting the catalytic metal or catalytic metal oxide is an important factor that influences the catalytic performance.

The carrier not only shapes the catalyst for practical use, but also allows the catalyst particles to be uniformly dispersed to increase the contact area with the gas, and also to select the reaction by adjusting the spacing between the catalyst metal particles. It is very important in configuring the catalyst body, such as making it possible to perform the following functions.

The following conditions are required for the carrier.

(1) The shape suitable for the reaction type can be maintained (2) The physical strength is large (3) The surface area and pore structure are optimal (4) The quality can be obtained stably and the quality can change during the reaction (5) Excellent heat resistance (6) Appropriate thermal conductivity and specific heat (7) Improvement in activity selectivity can be expected due to effects such as effective surface area and pore distribution (8) Taking platinum catalysts as an example of low cost, activated alumina is one that relatively satisfies the above conditions.

Activated alumina certainly has a large specific surface area and is a preferable phase, but it has the following drawbacks.

First, manufacturing costs are high.

This is because activated alumina is supported on the surface of a molded body, such as a honeycomb-shaped sintered body, which increases the manufacturing cost.

Activated alumina is only stable up to about 1200°C, and it is not possible to directly obtain a sintered body of activated alumina.
Therefore, the process described above has no choice but to be adopted.

There is also a so-called pellet-type product molded only from activated alumina, but this pellet-type product cannot normally be used for household use because of the large pressure loss when installed in a gas flow path.

Although platinum catalysts are very excellent catalysts for oxidation, as mentioned above, they are not necessarily superior to metal oxides for all reactions.

For example, in the case of ethyl acetate, which is an organic exhaust gas, a metal oxide mainly composed of manganese oxide has better activity at low temperatures than a platinum catalyst.

Generally, metal oxide catalysts have higher activity for compounds having intramolecular oxygen in the reaction gas, such as hydroxyl groups, ester groups, or ketone groups.

As described above, when a metal oxide catalyst and a platinum group catalyst are present at the same time as an oxidation catalyst, the applications are very wide.

From this point of view, the present inventors first proposed a catalyst body in which lime aluminate is used as a binder, a metal oxide is added as one of the carrier components to form a carrier, and a platinum catalyst is supported.

This catalyst body combines the features of a metal oxide catalyst and that of a platinum group catalyst, and furthermore, as a combined effect, it exhibits better performance than either individual catalyst.

Moreover, since it uses lime aluminate as a binder, it can be molded into any shape, has sufficient strength without heat treatment, and is inexpensive. It has excellent features.

Although it has many advantages as mentioned above, a catalyst body in which a platinum group catalyst is supported using lime aluminate or a metal oxide as a carrier has the following drawbacks.

First of all, when the catalyst body is exposed to high temperatures (600° C. or higher) or is placed in a locally reducing atmosphere, the metal oxide is reduced and the performance deteriorates.

Metal oxides are thermally unstable and can act as catalysts, such as Mn and Cu.
, Co, Ni, Cr, Fe oxides undergo thermal transformation T
If we take MnO2 as the example, it changes as shown below.

Mn 02 is catalytically active up to 650°C, after which it transforms into Mn 203.

The same applies to other metal oxides; heating reduces the metal oxide and its initial activity decreases.

This not only causes a deterioration in performance, but also causes a change in color, which is unsightly and is a fatal defect, especially when used as a household catalyst.

Furthermore, in a catalyst body in which a metal oxide and a platinum group catalyst coexist, the metal oxide is more easily reduced due to the oxidizing power of the platinum group catalyst, resulting in discoloration even at low temperatures.

This reduction can occur not only during use but also during the manufacturing process of the supported platinum group catalyst.

As described above, although conventional catalyst bodies have performance features of both metal oxides and platinum group catalysts, they have a number of drawbacks.

The present invention improves this and further provides a catalyst body having excellent performance that cannot be obtained from conventional catalyst supports made of lime aluminate and metal oxides.

The first feature of the present invention is that it contains a composite oxide as a means to overcome the above-mentioned drawbacks.

A complex oxide is a higher-order compound consisting of two or more types of oxides, in which the presence of a base ion as an oxygen acid is not recognized in its structure.

The general formula is Ml 2+M ■3+204 (MIMB
represents a metal ion) and has a spinel-type structure.

Particularly effective for the present invention are MnF, +gF, MnF, +gF, which is a divalent metal ion with MBI represented by MIIIFe204.
e2+tCo2+, Ni2", Cu"-", Zn2+,
It consists of Ba2+ and the like.

Composite oxides with such compositions have high heat resistance and 1
Stable up to 000°C.

However, the catalytic performance of the composite oxide alone is poor.

In the present invention, this composite oxide is not used as a main catalyst, but is added to a carrier containing a metal oxide and used as a co-catalyst.

In a carrier made of a metal oxide and a composite oxide, the active species of the catalyst is the metal oxide, and the composite oxide is considered to function as a co-catalyst that has the effect of suppressing the reduction of the metal oxide.

This can be clarified by analyzing the metal oxides in the body of Life Test I.

Needless to analyze, this can be proven by the fact that no change in color of this carrier, that is, no change due to reduction of metal oxides, was observed after the life test.

The composite oxide and metal oxide do not exist as a solid solution in the carrier, but as a mixture independent of each other, but ion exchange is possible at the particle interface between each other, and this It is presumed that this action maintains the stability of the metal oxide at high temperatures.

Furthermore, in the coexistence of metal oxides and composite oxides, the highly heat-resistant composite oxides are interposed between the metal oxide particles, so even when fired at high temperatures, the specific surface of the metal oxides due to sintering There is little decrease in , and therefore there is little deterioration in performance.

Since the composite oxide not only has excellent heat resistance but also is chemically stable, it does not form a composite oxide with a spinel structure with other metal oxides added as promoters.

The reason for this is that a stable composite oxide already exists around the metal oxide from the beginning, and no other composite oxide is formed.

The preferred double oxide for the present invention has as one of its components:
Containing at least zinc oxide ZnO,
It contains ZnFe2O4 as spinel.

This ZnFe2O4 does not need to be added alone;
Preferably, it consists of a mixture of n Fe 204 and M n Fe 204.

Those containing ZnO as one of the components have particularly excellent heat resistance and are chemically stable.

MnFe2O4 has an excellent cocatalyst effect when Mn02 is selected as the metal oxide.

In addition, BaFe204 +CoFe204 and the like are also effective.

The amount of composite oxide added depends on the amount of metal oxide, but it is required to be at least 1 weight range or more.

If the amount is less than this, the object of the present invention cannot be achieved, and the effect of the metal oxide co-catalyst cannot be expected to be significant.

On the other hand, if it exceeds 40 weight range, the amount of lime aluminate and metal oxide added becomes small, which is not preferable because the strength of the support and the catalytic ability of the metal oxide decrease.

The object of the present invention can be achieved if the ratio of composite oxide to metal oxide is in the range of 1:10 to 10:1.

Further, it is desirable that the total content of the composite oxide and metal oxide in the carrier is less than 80% by weight.

The reason for this is that if the weight exceeds 80 weight range, problems such as the mechanical strength as a carrier will be weakened and the surface hardness will be reduced.

Therefore, the content is below 80 weight range, preferably below 50 weight range.

As described above, the catalyst carrier of the present invention is composed of at least lime aluminate, a metal oxide, and a composite oxide.

This carrier itself has a sufficient gas purifying effect in certain applications, and can also be used as a catalyst.

The present invention is further characterized in that one or more catalytic metals selected from the platinum group elements are supported on the carrier having the composition described above.

Next, each raw material and manufacturing method constituting the catalyst body of the present invention will be explained in detail.

First, the lime aluminate used as a binder in the present invention is
As a component of cement, it is usually divided into alumina cement and portland cement.

Alumina cement is generally mA7203/ncaO
It is expressed as m'5i02・rI for Portland cement.
'CaO.

Portland cement is in high demand and is inexpensive, but it has drawbacks such as low heat 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.

Usually, the composition of commercially available alumina cement is composed of lime aluminate and iron oxide, and when the lime content of lime aluminate exceeds 40% by weight, the mechanical strength of the support increases, but the heat resistance decreases. At the same time, it reacts with heavy metal oxides at high temperatures, and for example, at temperatures above about 650° C., manganese oxides produce Ca Mn 204 and the like, 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 increases, and productivity also deteriorates.

Moreover, when the arana 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 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 higher.

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

The preferred composition of the alumina cement is a lime content of 15 to 40 parts by weight, especially 30 to 40 parts by weight, an alumina content of 35 to 80 parts by weight, especially 40 to 60 parts by weight, and an iron oxide content of 0.3 to 20 parts by weight, especially 2 to 10 parts by weight. He is in charge of 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 sufficiently withstand temperatures of 300°C or higher, high alumina cement is preferably used to withstand temperatures of about 700°C or higher.

A catalyst carrier using alumina cement as a binder may be composed of this cement alone, but preferably contains a base aggregate described below.

In this case, alumina cement acts as a binder, and its amount is small, estimated to be 20% by weight.

If this amount is small, the mechanical strength of the molded product will be weak and the surface hardness (abrasion resistance strength) will be low, which is not preferable.

The inventors of the present invention have studied various blending ratios, and as a result, have found preferred blending ratios depending on the shape of the molded product, as shown in the following table.

Here, the pellet type refers to one shaped into a rod, sphere, or square shape, and because it serves as a catalyst carrier with a small volume, it has little effect on spalling resistance such as thermal breakage (cracking). Even if the base aggregate is small, there is no need to worry about it breaking at high temperatures.

On the other hand, honeycomb type refers to a cylindrical, columnar, or plate-shaped type with many circular, oval, or square holes, and because it has a large volume as a catalyst carrier, it is heat-resistant. This has a large effect on the resistance to spalling such as mechanical failure, so it is necessary to use a large amount of base aggregate and to reduce expansion and contraction at high temperatures.

Next, the heat-resistant base aggregate used together with the binder will be described.

Although lime aluminate alone as a binder has sufficient strength, it is desirable to add a heat-resistant base aggregate at the same time.

The reason for this is that when it is integrally molded into a honeycomb shape or the like, if only lime aluminate is used, cracks will appear when heated, so by adding base aggregate, the heat resistance strength of the carrier can be further improved.

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, as well as magnesia and chromium. , dolomite, maguro, and chromag are preferably used.

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

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

These base aggregates have S+02 as the main component.

As silica-alumina base aggregate, chamotte, waxite,
There are high aluminas, etc., and 5i02-A1203 is the main component.

α-AA 2 o3. as alumina base aggregate. β-Ai
j 203, γ-AJII! 203. ρ-A1203
etc.

Note that instead of using alumina, animinium hydroxide may be used as a starting material and converted into alumina by heat treatment.

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

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

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).
It is uneconomical to obtain a cheap catalyst carrier.

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.

Furthermore, fibrous inorganic materials can be used as the base aggregate, and are particularly effective in reducing deterioration of mechanical strength at high temperatures.

As this fibrous inorganic material, asbestos, glass fiber, etc. can be used.

Asbestos containing ordinary magnesium silicate as a main component is sufficient, but especially when used at high temperatures, it is necessary to use one with good fire resistance.

The main types of asbestos are warm asbestos, blue asbestos, amphibole asbestos,
There is direct asbestos, etc.

On the other hand, the glass fibers are preferably yarns, rovings, chopped strands, chopped strand mats, glass wool, etc., and it is preferable to use alkali-resistant glass fibers so as to withstand the alkalis in alumina cement.

Depending on the purpose and shape of the catalyst, the length of the glass fiber,
You need to decide on the thickness and whether it will be matte or chopped strands.

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

For small-volume particles such as pellet types, even particles with fine particle size can be used, but for large-volume particles such as honeycomb types, it is necessary to mainly use large-sized particles.

In particular, the honeycomb type has a large volume, so spalling resistance is important, and by using a material with a large particle size,
The expansion and contraction of the catalyst carrier can be reduced, and the mechanical strength of the catalyst carrier can be increased.

Among these, it is best to mix large and small particle sizes.

Furthermore, the important role of the base aggregate is to increase the specific surface area of the catalyst carrier, which is an essential requirement for the catalyst carrier.

Among the base aggregates mentioned above, it is particularly preferable to use base aggregates with a large specific surface area, such as γ-AIJ 203 and zeolite.

There are two ways to increase the specific surface area of a catalyst carrier: one is to increase the specific surface area with a base aggregate, and the other is to make the surface porous by incorporating a thermally decomposable salt during catalyst carrier manufacturing. As the organic salt, organic salts are particularly preferred.

The surface of the carrier can also be made porous by containing alcohol, carboxymethyl cellulose, methyl cellulose, etc. and heat treating it.

Next, we will discuss metal oxides.

In the present invention, the metal oxide is a catalyst having catalytic activity, and is an element constituting the catalyst body together with a catalyst metal selected from the platinum group element group.

The metal oxide used in the present invention is a metal oxide having catalytic ability, and main ones include Mn, Cu, Co, Ni,
It is an oxide of a metal selected from Cr and Fe.

There is no need to use only one type of oxide, and any type of oxide can be selected depending on the application.

Among these metal oxides, manganese oxide is particularly effective when coexisting with a catalyst metal consisting of a platinum group element.

Among manganese oxides, electrolytic manganese dioxide produced by electrolysis is particularly desirable, and its crystal form is γ-M.
It shows nO2.

γ-MnO2 has a specific surface area of 40 to 60 rrl'/
g and is an excellent catalyst with sufficient catalytic ability by itself, but as mentioned above, the drawback is that it transforms into β-Mn 02 at 250°C and into α-Mn 20 s at 650°C. As a result, performance deteriorates.

Among these electrolytic manganese dioxides, the ones with excellent performance are β and γ-MnO2, and when transformed into α-Mn203,
Performance is poor.

On the other hand, the carrier to which the composite oxide of the present invention is added is
-MnO2 does not transform into aMnOs even at temperatures above 650°C.

The complex oxide acts as an electron donor promoter because
The material is not limited to manganese oxide, but also includes copper oxide, cobalt oxide, nickel oxide, chromium oxide, and iron oxide.

The amount of metal oxide added to the carrier varies depending on the purpose, but it is necessary to have a range of 1 weight or more.

If the amount is less than 1 weight class, the object of the present invention cannot be achieved, and the performance of the catalyst will depend only on the platinum group element.

On the other hand, if the weight exceeds 40% by weight, not only will the strength as a carrier be weakened, but the amount of the composite oxide to be added to coexist with the metal oxide will also be reduced, making it impossible to expect a promoter effect.

Furthermore, if there is a large amount of metal oxide, it will be reduced by the oxidizing power of the supported platinum group element, resulting in poor performance.

Therefore, the preferred amount of the metal acid ratio to be added is 1 to 40% by weight.

Next, the catalyst metal selected from the platinum group element group to be supported on the carrier will be described.

Platinum group elements include ruthenium, rhodium, palladium,
These are osmium, iridium and platinum.

In order to support these metals on a carrier as a catalyst, the carrier is impregnated or coated with a solution of each salt.

In the case of ruthenium, the salts used are RuCJ'3, (NH4) 2 Ru C1l 5, K
2 Rub4+ H20z Ruthenium nitrate, etc.

Rhodium is RhCA3, palladium is PdCl! 2,
[Pd(N)(3)4]C12・H2O, (NHI)2
PdC14, osmium is H2O5C16, (NH4)
20sC16, Iridium is IrC73, H2IrC#
6, (NH4) 2 I rC16, platinum is H2PtC
l4, H2PtCl6, P t (NH3)2 (NO
2) 2 is a typical example.

These 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 the optimum concentration is determined 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 weight, a catalyst body with high performance both in initial performance and lifetime performance can be obtained.

That is, conventional platinum catalysts use carriers such as alumina and cordierite, and the supported amount of platinum is 0.5 to 0.1 weight class, and when the supported amount is less than 0.1 weight class, 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 very small.

There is a significant relationship between the amount of supported catalyst and performance, and normally, as the amount of supported catalyst increases, performance will improve accordingly, but if it exceeds 0.1 weight class, problems such as falling off of the catalyst will occur.

Furthermore, by supporting two or more kinds of metal oxides in addition to the catalyst amount, the purpose of use, shape, low-temperature activity, life, etc. can be improved.

Next, a method for manufacturing the catalyst body of the present invention will be explained.

First, heat-resistant base aggregate, metal oxide, and composite oxide are dry-mixed with alumina cement as necessary.

After dry mixing, water necessary for molding is added and molded.

It is optional to add a lubricant such as carboxymethyl cellulose, methyl cellulose, colloidal silica, colloidal alumina, or alcohol as a molding aid.

After molding, the molded product is cured to some extent and then cured.

Curing means that lime aluminate absorbs moisture and becomes as shown below.

mAl2O3・nCaO+H20 → mAl2O3・nC
The a0-xH20 curing is performed in steam or hot water for a certain period of time.

After complete curing, dry. Next, a solution of a metal salt selected from the group of platinum group elements is applied.

The coating is carried out by impregnating the carrier in a solution or by applying it to the required surface with a spray gun.

Thereafter, it is heated and reduced to form a catalyst.

Reduction can be carried out simply by heat treatment, but it can also be carried out in a hydrogen stream or by using other reducing agents such as hydrazine or formalin.

The catalyst body of the present invention is obtained by the above-mentioned operations, and the obtained catalyst body takes advantage of the characteristics of both the metal oxidizing part and the catalyst body consisting of a platinum group element, and furthermore, it is possible to add a composite oxide to the catalyst body. This overcomes the drawbacks of conventional metal oxides.

Next, an example will be described.

Example 1 Alumina cement 40 parts by weight CaO 34 parts by weight Al2O 3 parts 48 I / Fe2O 3 parts 10 If Others 8 // Heat-resistant base aggregate silica sand 5 parts by weight Glass fiber 2 // Metal oxide γ-MnO 25 parts by weight Composite oxidation Material ZnFe2O47, 5 parts by weight Mn Fe 204 7.5 tt After mixing the above materials, 15 parts by weight of water was added and wet mixed.

After that, use an extrusion molding machine to make a diameter of 5 mm and a length of 5 to 10 mm.
Form into pellets.

After curing, cure in hot water at 95°C for 1 hour and dry.

Selecting pt as a catalyst, chloroplatinic acid H2PtC116.
6H201F is dissolved in 100 cc of ethyl alcohol, and the catalyst barrel carrier is impregnated in this solution.

Calculating the amount of supported Pt from the absorbed solution is 0.
．． There were 033 parts by weight.

Next, this carrier was heat-treated at 400° C. for 1 hour in an air atmosphere to obtain a catalyst sample.

. As a purification ability test for this sample, a flow-type reactor was used at an air velocity of 10,000 hr-1 and a CO concentration of 1,010 hr-1.
00rl1 air balance) at each temperature, CO2 of CO
The conversion rate to was measured and defined as the purification rate.

CO was measured using a measuring device using a non-dispersive infrared absorption method.

The results are shown in Figure 1. Example 2 Using a catalyst carrier having the same composition as in Example 1, a catalyst made of a platinum group element shown in Table 1 was supported, and the Co purification rate was measured.

Chloride was used as the starting material for each platinum group element.

The results are shown in Table 1.

As is clear from the table, those containing at least Pt as a catalyst species are more likely to have Co than those containing other platinum group elements alone.
Excellent purification rate.

Example 3 The sample of Example 1 was designated as A, and as a comparative example, a carrier molded from the catalyst carrier composition of Example 1 except for the composite oxide was used, and the other conditions were the same, and B was used. It was installed in the exhaust gas path of a combustion machine and a life test was conducted.

The temperature of the catalyst layer is 500°C, and the Co concentration before passing through the catalyst layer is 5.
0-80 rpm, space velocity is 10000 hr-1.

A comparison of these Co purification rates is shown in FIG.

As is clear from the figure, the product of the present invention shows no deterioration even after 800 hours, but the product of the comparative example without the addition of composite oxide shows severe deterioration even though the initial performance is not much different.

From this, it can be said that the effect of the composite oxide of the present invention is remarkable.

Example 4 In the catalyst carrier of Example 1, the composition and addition amount of the heat-resistant base aggregate were varied as shown in Table 2, and the Co purification rate was measured.

All other conditions are the same as in Example 1.

Example 5 In the catalyst carrier of Example 1, the composition and amount of metal oxide added were varied as shown in Table 3, and the CO purification rate and hydrocarbon (propane C3H8) purification rate were measured.

The catalysts were all Pi and Pd (ratio of both 2:l), the total amount of deposited was 0.03% by weight, and the heat treatment temperature was 380° C. for 1 hour.

The concentration of hydrocarbons was 100F, and the measurement was done using a hydrocarbon meter.

Example 6 Converted The composition of the carrier excluding the composite oxide is as shown below.

Alumina cement 40 parts by weight γ-Mn02 1 Q n Silica sand 5 // Alkali-resistant glass fiber 2 parts by weight H2025rl To this material, the type and amount of composite oxide added were varied as shown in Table 4.

Pt was selected as the catalyst metal, and the shape and manufacturing method of the carrier were the same as in Example 1.

The purification rate test was conducted using the life test shown in Example 3.

The results are shown in Figure 3. As described above, since the present invention includes a composite oxide, it overcomes the drawbacks of the conventional catalyst consisting of a metal oxide and a platinum group catalyst, and provides a novel catalyst. The characteristics of catalyst bodies containing substances can be summarized as follows.

(1) Since it acts as a co-catalyst for the metal oxide catalyst, it has excellent purification ability and does not deteriorate even when used for a long time.

(2) It has excellent heat resistance, so it is chemically and physically stable even if it is locally exposed to high temperatures.

(3) It has excellent strength as a carrier.

(4) No discoloration due to reduction is observed.

(5) Since the characteristics of metal oxides and platinum group catalysts can be fully exhibited, they are particularly effective in the following reactions.

carbon monoxide oxidation Co Jusai 02 → CO2 Complete oxidation of various hydrocarbons H, C, +02→H20+CO2 Oxidation of SO2 S02+I02→5O3 Oxidation of NO NO 10% 02 → NO2 Oxidation of cooking oil smoke

[Brief explanation of drawings]

Figure 1 is a diagram showing the CO purification rate at various temperatures of the catalyst body according to the present invention, and Figure 2 is a diagram showing the CO purification rate of the catalyst body according to the present invention and the comparative example.
FIG. 3 is a graph showing the change in O purification rate over time, and is a graph comparing the change over time in the CO purification rate of catalyst bodies using supports containing various composite oxides.

Claims (1)

[Claims] 1. At least lime aluminate, Mn, Cu,
Co. An oxide of a metal selected from the group consisting of Ni, Cr and Fe, and Z n F e 204 and M n F
1. A catalyst body for exhaust gas purification, comprising a carrier made of a composite oxide selected from the group consisting of e.g. 204, and a platinum group metal catalyst supported on the carrier. 2 The aluminate lime in the carrier is 20 to 98% by weight,
The catalyst body for exhaust gas purification according to claim 1, wherein the metal oxide has a weight ratio of 1 to 40 and the oxide has a weight ratio of 1 to 40.