JPS5950377B2 - Manufacturing method of catalyst for exhaust gas purification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention deals with harmful components such as hydrocarbons, carbon monoxide, and nitrogen oxides contained in the combustion gas of petroleum and coal-based fuels, and organic substances emitted from gas stations and various manufacturing plants. The present invention relates to a method for producing an oxidation catalyst for exhaust gas purification that renders harmful components that pollute the atmosphere, such as solvent vapor, harmless.

Conventional catalysts of this type include porous pellet catalysts or honeycomb structures in which activated platinum is supported on alumina as a carrier, or metal oxides such as manganese and copper with cobalt and silver. Hopcalite catalysts combined with oxides such as oxides are widely used.

However, the former (alumina-platinum type) has a catalytic ability of 15
A relatively low temperature of 0°C to 200°C is not sufficient, and
The latter (metal oxide type) exhibits remarkable catalytic activity in the above-mentioned low temperature range, but since these metal oxides are harmful if inhaled by the human body, safety equipment is required in the production equipment, and
There are several problems, such as the need to be careful about the health management of working tools.

The present invention is intended to solve these problems, and focuses on a calcium silicate-platinum catalyst as a catalytic material that is not harmful to the human body. The object of the present invention is to provide an exhaust gas purifying catalyst having the following properties.

The invention of claim 1 is characterized in that calcium silicate powder is impregnated with and occluded with a chloroplatinic acid solution, and after this is dried and dehydrated,
400℃~1 in a reducing atmosphere under city gas distribution
This is a method for producing an oxidation catalyst for purifying exhaust gas containing carbon monoxide, hydrocarbons, and organic solvent gas, which is characterized by performing heat treatment within a temperature range of 200°C.

Examples thereof will be described below.

Add 10 cc of 3.9% chloroplatinic acid aqueous solution to 10 g of reagent-grade calcium silicate powder to impregnate and occlude it, mix thoroughly to form a uniformly occluded slurry, and dry at 120°C for 2 hours while stirring with a spoon. completely dehydrated to a pale yellow powder.

Next, this powder was placed in a magnetic crucible, and placed in an electric furnace heated to 300°C under a flow of city gas of 750 cc per minute.
Heat treatment was carried out for 1 hour while gradually increasing the temperature to 50° C. to obtain a gray-black catalyst powder with platinum attached to the surface of each particle of calcium silicate powder.

The composition of the sample taken out after slowly cooling the electric furnace to room temperature was 98.5% calcium silicate and 1.5% activated platinum.

This is designated as sample 1. To 6 g of the catalyst powder of sample 1, add 16 g of alumina-silica-based water-based liquid paste (Sumita Kagaku KK product name Sumiceram 5L2B) and 11 g of water.
The mixture was kneaded for several minutes to make it viscous, and then formed into small spheres with a diameter of 4 to 8 mm by hand, and dried and dehydrated at 120° C. for 2 hours.

Its composition is 27% calcium silicate, 0.4% activated platinum,
Sumiceram 512B (Assembled) 72.6%
It is.

The invention of claim 2 characterized by this is obtained by kneading the catalyst powder of sample 1 prepared by the method of claim 1 with alumina-silica-based aqueous-liquid paste or alumina-based acidic-liquid paste. After making it viscous and molding it into a predetermined shape and drying and hardening, the catalyst body was impregnated with a chloroplatinic acid solution and occluded, dried and dehydrated.
This is a method for producing an oxidation catalyst for purifying exhaust gas containing carbon monoxide, hydrocarbon, and organic solvent gas, which is characterized by performing heat treatment within a temperature range of 00°C to 1200°C.

Examples thereof will be described below.

Add 4 cc of 3.9% chloroplatinic acid aqueous solution to 7 g of the small spherical medium of Sample 2 to impregnate and occlude it, dry it at 120°C for 2 hours to dehydrate it, and then use an electric furnace to absorb city gas at 75% per minute.
In a reducing atmosphere under 0 cc flow, at a temperature of 450
A heat treatment was performed at ℃ for 1 hour, and an active platinum layer was supported on the outer surface of the small spherical catalyst body.

The composition of the sample taken out after slowly cooling the electric furnace to room temperature was 27% calcium silicate, 72.6% Sumiceram 5L2B, and 0.4%+0.8% activated platinum.

The invention of claim 3 characterized by this is that calcium silicate powder is kneaded with alumina-silica-based aqueous-liquid paste or alumina-based acidic-liquid paste to make it viscous, and this is formed into a predetermined shape and dried and hardened. After that, carbon monoxide is impregnated and occluded with a chloroplatinic acid solution, and after drying and dehydration, heat treatment is performed in a reducing atmosphere under city gas flow within a temperature range of 400 ° C. to 1200 ° C.
This is a method for producing an oxidation catalyst for purifying exhaust gas containing hydrocarbon and organic solvent gases.

Examples thereof will be described below.

6 g of calcium silicate powder, 16 g of alumina-silica aqueous liquid paste (Sumiceram 812B) and 11 g of water
g, knead for 10 minutes to make it viscous, and mix by hand for 4~
It was molded into a small spherical body with a diameter of 8 mm, and dried and dehydrated at 120° C. for 2 hours.

7 g of this small spherical catalyst carrier was impregnated with 4 cc of a 3.9% chloroplatinic acid aqueous solution, dried and dehydrated at 120°C for 2 hours, and then heated in an electric furnace in a reducing atmosphere with city gas flowing at 750 cc/min. A heat treatment was performed at a temperature of 450° C. for 1 hour to obtain a calcium silicate-alumina-silica-activated platinum-based small spherical catalyst.

The composition of the sample taken out after slowly cooling the electric furnace to room temperature was 27% calcium silicate, 72.2% Sumiceram 312B, and 0.8% activated platinum.

This is designated as sample 4.

In order to compare the catalysts of Samples 1 to 4 prepared by the production method of the present invention with conventional alumina-platinum catalysts,
An alumina-activated platinum catalyst powder similar to that of Sample 1 was prepared using a commercially available reagent grade alumina powder.

Its composition is 98.5% alumina and 1.5% activated platinum.

This is designated as sample 5. The comparative test of these five samples was conducted using an infrared spectroscopy method using a glass container with a volume of 250 cc, which was filled with air containing 15% carbon monoxide per 1 g of each sample.
The amount of carbon dioxide gas 20 minutes after the contact reaction was carried out at 150° C. was measured by infrared transmittance.

Calculated from the measured values, sample 1 is 10%, sample 2 is 4.
5%, Sample 3 was 6.4%, Sample 4 was 5.5%, and Sample 5 was 1.5%.

From these results, it can be seen that Samples 1 to 4 produced by the production method of the present invention have significantly better catalytic performance than the conventional alumina-platinum catalyst (Sample 5) in the low temperature range of 150°C.

These samples 1゜2, 3. The reason why sample 1 has the most active catalytic activity among samples 2 and 4 is because it is a powder and has a large area of action. 3. The reason why sample 3 has particularly high catalytic activity among samples 4 and 4 is because it was impregnated with chloroplatinic acid twice.

In the present invention, it is also possible to create a reducing atmosphere using hydrogen gas instead of city gas during the heat treatment.

However, hydrogen gas is more expensive than city gas and requires careful handling because it uses a pressure vessel.

On the other hand, city gas is cheap and non-hazardous, and contains methane, ethane, propane, carbon oxide, etc. in addition to hydrogen, so heat treatment in an atmosphere containing these gases It has an affinity for gases and is effective as an oxidation catalyst for combustion gases of the same type as these gases.

In the present invention, instead of the alumina-silica aqueous-liquid paste used as the binder and catalyst carrier, an alumina-based acidic-liquid paste can be used to obtain the same solidified catalyst as in the example.

That is, Sumiceram 5202 manufactured by Sumitomo Chemical Co., Ltd. as the alumina-based acidic aqueous-liquid paste was used as the alumina-silica-based aqueous-liquid paste (Sumiceram 31) in Sample 4.
2B) was used as a molding binder, and the same as sample 4 was used.
Activated platinum in the same proportion as Sample 4 was added to the molded carrier, which was molded into the same size and shape using the same process and dried at 120°C for 2 hours, and then heat-cured at 300°C for 1 hour. Sample 6 was obtained by compositely integrating the above, and it was measured using the same infrared grating method as described in the above example.
The concentration of carbon dioxide produced was <5.5%, the same as sample 4.

Note that the mechanical strength of the alumina-based acid (liquid paste) is more acidic at PH01, so the calcium silicate particles and the paste and particles are slightly more compatible with each other, and in addition, at 300°C By heat treatment and curing, a molded body more robust than Sample 4 using alumina-silica-based aqueous-liquid paste was obtained.

As mentioned above, the solid catalyst consisting of the three-component system of calcium silicate-alumina/silica-based aqueous liquid paste or alumina-based acidic liquid paste/activated platinum has excellent catalytic ability, and the catalytic ability can be improved by solidification. There is almost no decline.

Moreover, it has sufficient mechanical strength, and there is no risk of embrittlement or powdering even when heated to a rapid temperature increase of 1,200℃.
It is stable even at temperatures above ℃.

This is because the alumina-silica aqueous-liquid paste or the alumina-based acidic-liquid paste is thought to combine with calcium silicate to act as a strong binding agent.

The reason why the heat treatment temperature in the present invention is set to 400°C to 1200°C is that the lowest temperature at which chloroplatinic acid is reduced with the catalyst supported is 400°C, and the catalyst support (calcium silicate-alumina silica based aqueous The long-term heat resistance temperature of liquid paste or alumina-based acid-liquid paste is 1200℃.
This is based on the fact that the temperature is ℃.

In addition, samples 1 to 5 and sample 6 described in the above examples were subjected to the same infrared spectroscopic variation method as in the above examples, targeting methane, which belongs to a difficult-to-oxidize substance among hydrocarbons.
Filled with air containing 2.6% of this, 1 g of sample was loaded, and a catalytic oxidation reaction was carried out for 15 minutes at 200°C ± 5°C.
When the methane concentration reduction rate after 5 minutes was measured and compared, sample 1 was 18%, sample 2 was 15%, and sample 3 was 17%.
, sample 4 was 16%, sample 5 was 13%, and sample 6 was 16%.

As described above, the production method of the present invention is similar to the conventional alumina-platinum catalyst, as is clear from the comparison of various examples targeting methane and the comparison of various examples targeting carbon monoxide described above. The activity characteristics as an oxidation catalyst are
In particular, it has excellent effects against hydrocarbons, organic solvent gases containing hydrocarbons, and carbon monoxide, which can be obtained as powders and solid bodies.

Claims (1)

[Claims] 1 Calcium silicate powder is impregnated and occluded with a chloroplatinic acid solution, and after drying and dehydrating, heat treatment is performed within a temperature range of 400°C to 1200°C in a reducing atmosphere under city gas distribution. Method 2 for producing an oxidation catalyst for purifying exhaust gas containing carbon monoxide, hydrocarbons, and organic solvent gases, characterized in that calcium silicate powder is impregnated with and occluded with a chloroplatinic acid solution, dried and dehydrated, and then subjected to city gas distribution. The catalyst powder obtained by heat treatment within the temperature range of 400°C to 1200°C in a reducing atmosphere of After molding into a shape and drying and hardening, it was impregnated and occluded with a chloroplatinic acid solution, dried and dehydrated, and then heated at 400°C in a reducing atmosphere under city gas flow.
Method 3 for producing an oxidation catalyst for purifying exhaust gas containing carbon monoxide, hydrocarbon and organic solvent gases, characterized by carrying out heat treatment within a temperature range of ~1200°C. After activation by kneading with alumina-based acidic liquid paste 1, molding it into a predetermined shape and drying and hardening, it is impregnated with a chloroplatinic acid solution and occluded, dried and dehydrated. 400℃~ in atmosphere
A method for producing an oxidation catalyst for purifying exhaust gas containing carbon monoxide, hydrocarbons, and organic solvent gas, characterized by performing heat treatment within a temperature range of 1200°C.