JPS6377542A - Catalytic body for combustion of kerosine-based fuel - Google Patents

Abstract

PURPOSE:To enhance heat resistance and durability of the titled catalytic body by depositing 20-200g/l-carrier activated alumina and 0.1-2g/l-carrier Pt on a monolithic carrier and depositing Pt at the specified position of the surface to be deposited. CONSTITUTION:A catalytic body for burning kerosine-base fuel is formed by coating and depositing 20-200g/l-carrier activated alumina and 0.1-2g/l-carrier Pt on a monolithic carrier and also depositing >=40% of total Pt amount to be deposited in a range within 5mum from the surfacemost layer of the coated layer and depositing >=60% of total Pt amount to be deposited in a range within 10mum from the surfacemost layer. As the raw material of Pt, dinitrodiaminoplatinic acid is preferably used. As the monolithic catalyst, cordierite, mullite and alpha-alumina, etc., are used and the size of the carrier is preferably small to enhance combustion efficiency and is regulated to about 200-600cell/cm<2>.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a catalyst body for combustion of kerosene-based fuel.

Specifically, vaporized gas from kerosene fuel is catalytically burned with air on a catalyst to produce nitrogen oxides (hereinafter referred to as NOx).
, - Obtain combustion gas that does not substantially contain harmful components such as carbon oxide (hereinafter referred to as CO) and unburned hydrocarbons (hereinafter referred to as UHC), and use the heat amount as a heat source for oil stoves, oil fan heaters, etc. The present invention relates to a combustion catalyst for use.

[Prior art]

A kerosene stove used as a home heating appliance.

Oil fan heaters and the like are generally made by burning kerosene-based fuel with a flame and utilizing the heat generated. However, recently, as buildings become more airtight, the emission of harmful components such as Co and NOx has become a problem. On the other hand, there is a method of producing a high-temperature gas that does not substantially contain Co, UHC, or NOx by catalytically flameless combustion of a dilute mixed gas in which a fuel such as hydrocarbon is mixed with air at a low concentration that does not fall within the combustible range on a catalyst. Various systems have been proposed that use this clean, high-temperature combustion gas as a heat source for heating appliances, and some of them have been put into practical use, such as for heating outside cliffs. Catalysts used for these purposes include alumina fibers impregnated with precious metals,
Alternatively, a cordierite monolith carrier coated with active ingredients such as a heat-resistant metal oxide and a noble metal is generally used.

However, since all of these systems are used at a catalyst surface temperature of about 400 to 600 degrees Celsius, the catalyst surface does not become red hot, so it is necessary to visually check whether combustion is being maintained or not. Can not do it.

In addition, the amount of heat generated per unit volume of the catalyst is small, resulting in an increase in the size of the combustion equipment.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned conventional problems, and it increases the catalyst surface temperature as much as possible, makes the combustion visible due to its dark red color, and also increases the efficiency of the calorific value. The object of the present invention is to provide a catalyst for combustion of kerosene-based fuel, which has heat resistance and durability at 700 to 1000° C. and has a reduced amount of noble metal supported.

[Structure of the invention]

In order to achieve this objective, the present inventors conducted intensive studies on catalytic combustion under various conditions using vaporized gas of kerosene-based fuel, and found that platinum-based catalysts are superior as combustion catalysts for kerosene-based fuel. The present inventors have now completed the present invention by discovering that high combustion efficiency is exhibited when platinum is supported at a high density on the surface of the catalyst. That is, the combustion catalyst according to the present invention is formed by coating and supporting activated alumina and platinum on a monolithic carrier. 0.1 to 2 E%, preferably 0.5 to 1 g, and furthermore, platinum is at least 40%, preferably at least 60%, of the total amount of platinum supported within 5 μm of the outermost layer of the coating layer, and It is characterized in that 60 or more, preferably 80 or more of the total amount of platinum supported is carried within 10 μm from the outermost layer.

As the monolith carrier, any carrier commonly used in the field can be used, especially cordierite, mullite, α-alumina, zirconia, titania, titanium phosphate, aluminum titanate, betalite, spodumene, and aluminium. Silicate, magnesium silicate, zirconia-spinel, zirco/-mullite,
Heat-resistant ceramic materials such as silicon carbide and ion nitride, and metal materials such as Kanthal and Feclaroy are used.

The cell size of the monolithic carrier is preferably small in order to further improve combustion efficiency, and is usually 20 cm square.
A cell having 0 to 600 cells is used.

The total catalyst layer length is preferably short, and is usually 10
~50m is adopted.

The catalyst of the present invention is usually prepared by adding 1 liter of the carrier to the above-mentioned monolithic carrier.
After coating and supporting activated alumina consisting of 20 to 200 g
0.1 to 2 g of platinum per liter of carrier is immersed in an aqueous solution containing dinitrodiaminoplatinum having a temperature of
, preferably 0.5 to 1 g, and after drying, 400 g
1 to 1 at a temperature of ~1000°C, preferably 500 to SOO°C
It can be obtained by baking for 24 hours, preferably 2 to 6 hours. If the amount of platinum supported is increased here,
The loading ratio in the inner layer region of the coating layer increases sequentially, and if more than 92 g of platinum is loaded per carrier, the amount of platinum that does not effectively contribute to the reaction will increase, which is undesirable.

Furthermore, when a platinum source other than dinitrodiaminoplatinum, such as chloroplatinic acid, is used, the proportion of platinum supported in the inner layer region of the coating layer increases, which is not preferable.

In addition, as a manufacturing method other than the above, activated alumina is impregnated in advance with a solution containing dinitrodiaminoplatinum or a water-soluble salt such as chloroplatinic acid.
1 at a temperature of ~1000°C - preferably 500-800°C
A platinum-containing alumina is prepared by firing for 24 hours, preferably 2 to 6 hours, and then the above-mentioned platinum-containing alumina is applied directly to the monolith carrier or by coating 20 to 200 g of activated alumina per liter of the carrier. A catalyst in which platinum is optimally supported can also be obtained by coating and supporting 2 to 30 g of platinum per liter of carrier.

A more preferable method is to divide the platinum-containing alumina coating layer into several stages to further optimize the platinum loading distribution.

[Effect]

The above-mentioned catalyst body is characterized by a coating layer consisting of activated alumina and platinum, in which platinum is supported at a high density on the surface layer of the coating layer, and the platinum present at a high density is
In addition to increasing the combustion efficiency of hydrocarbons, its presence in the surface layer has the effect of making combustion in the gas phase occur continuously and smoothly.

[Effects of the present invention]

As described above, the platinum-based catalyst of the present invention improves combustion efficiency and makes effective use of platinum in catalytic combustion of kerosene-based fuel, and also has heat resistance in the temperature range of 700 to 1000°C.
Improved durability is expected.

As a result, an inexpensive and compact combustion catalyst can burn CO over a long period of time even in red-hot temperature ranges.

This enables catalytic combustion of kerosene-based fuel that does not substantially emit NOx or UHC, and can be applied to household heaters such as kerosene stoves and kerosene fan heaters.

This makes household heaters safer and harmless, which has a great effect.

〔Example〕

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

Example 1 25.4 diameter with 400 cells/inch square aperture
■, A cordierite honeycomb carrier with a length of 20 mm was coated with a slurry of activated alumina powder, dried, and then fired at 600°C in the air to form a carrier 1! A coating layer of 100 y was deposited per coat, and the coating layer had an average thickness of 50 μm.

Next, the carrier was immersed in an aqueous solution containing dinitrodiaminoplatinum heated to 80°C to adsorb the entire platinum solution, dried, and calcined in air at 600°C to obtain carrier 1! A completed catalyst was obtained by supporting 1y as platinum.

This catalyst is Electron Probe Micro
o Analysis (EPMA) results show that 63% of the total amount of platinum supported is within 5 μm from the outermost layer of the coating layer, and 85% of the total amount of platinum supported within 10 μm from the outermost layer, as shown in Figure 1. was.

Example 2 Activated alumina powder was impregnated with an aqueous solution containing a nitric acid solution of dinitrosyaminoplatinum, dried, and then heated at 600°C in air.
The powder was fired to produce Y4 alumina powder containing 8% platinum quart. This platinum-containing alumina powder was slurried and
It was coated on a cordierite honeycomb carrier with a diameter of 25.4 m and a length of 20 m with openings of cells/in2, dried, and then calcined in air at 600°C, supporting 24 g of platinum as 1y1 alumina per liter of carrier. A finished catalyst was obtained having a coating layer with an average thickness of 13 μm.

As a result of analysis by EP-I, this catalyst showed that platinum was uniformly supported over the entire coating layer, but because the coating layer itself was small, 4 μm of the total amount of platinum supported was within 5 μm from the outermost layer.
0%, 80% of the total amount of platinum supported within 10 μm from the outermost layer
% was supported.

Example 3 25.4 diameter with 400 cells/inch square aperture
A cordierite honeycomb carrier with a length of 20 m and a length of 20 m was coated with the activated alumina slurry, dried and then heated in air for 6 m.
It was fired at 00°C. The carrier after coating treatment was
100.9 alumina was supported per liter of carrier.

Next, this carrier was again coated with an alumina slurry containing 5% by weight of platinum prepared in the same manner as in Example 2, dried, and then calcined at 600°C to obtain 1 liter of the carrier. ! A finished catalyst was obtained, on which 20 g of platinum-containing alumina was supported per liter and a coating layer with an average thickness of 60 μm.

As a result of EPMA analysis, this catalyst showed that 44% of the total amount of platinum supported was within 5 μm from the outermost layer of the coating layer, and 88% of the total amount of platinum was supported within 10 μm from the outermost layer of the coating layer.

Example 4 A completed catalyst was obtained in the same manner as in Example 1, except that the amount of platinum supported was 0.5 E//l.

As a result of analysis by EPMA, this catalyst showed that 83 of the total amount of platinum was supported within 5 μm of the outermost layer of the coating layer, and 98 of the total amount of platinum was supported within 10 μm of the outermost layer of the coating layer.

Comparative Example 1 A finished catalyst was obtained in the same manner as in Example 1 except that chloroplatinic acid was used as the platinum source.

As a result of EPMA analysis of this catalyst, it was found that 20% of the total amount of platinum was supported within 5 μm from the outermost layer of the coating layer, and 37% of the total amount of platinum supported within 10 μm from the outermost layer.

Comparative Example 2 25.4 diameter with 200 cells/inch square aperture
A cordierite honeycomb carrier with a length of 20 m and a length of 20 gourds was coated with a slurry of alumina powder, and fired in air at 600°C to coat and carry #) 100S per 1 liter of carrier, with an average thickness of 50 μm. Got layers.

Then 0.2! ! An aqueous solution prepared by heating and dissolving citric acid of 30
The carrier was immersed in CH, heated to 80° C. for 10 minutes, and then dried at 100° C., thereby supporting 98 g of citric acid per liter of carrier on the surface layer. This carrier was then immersed in an aqueous solution containing a nitric acid solution of dinitrodiaminoplatinum, dried, and calcined in air at 600°C to obtain a catalyst in which II was supported as platinum per liter of carrier.

As a result of EPMA analysis, it was found that almost no platinum existed in this catalyst within 10 μm from the surface of the coating layer.

Comparative Example 3 Alumina powder was impregnated with an aqueous solution containing chloroplatinic acid,
After drying, it was calcined in air at 600°C to prepare an alumina powder containing 1% by weight of platinum.

This platinum-containing alumina powder was made into a slurry, which had a diameter of 25.4 m and a length of 2 with 400 cells/inch square openings.
It was coated on a cordierite honeycomb carrier weighing 0.0 kg, dried, and then fired at 600°C in the air to give 1 g of platinum and 99.9 g of alumina per liter of support. ! carry the ir,
A finished catalyst was obtained with a coating layer having an average thickness of 50 μm.

As a result of EPMA analysis, this melting medium was found to be
10 inches of the total amount of platinum supported within 10 μm from the surface layer, and 20 inches of the total amount of platinum supported within 10 μm from the surface layer.

Example 5 A sufficiently warmed cylindrical combustor was used, filled with the catalyst obtained in Example 1, and heated at an inlet temperature of 250°C for 1 minute. 90.17 g of kerosene was vaporized using an evaporator, and a kerosene vaporized gas-air mixture containing gas was introduced at a rate of 5 Nl per minute. The amount of NOx*UHC discharged and the temperature at the outlet of the catalyst layer were measured. In this case, the linear velocity at the inlet of the catalyst layer is approximately 31 (m/see), and the SV is approximately 29,600 h.
It was r.

As a result, the catalyst bed outlet temperature was 870°C, the catalyst body was red hot, and no Co, NOx, or UHC was detected.

This performance was maintained for 1000 hours.

Example 6 A combustion experiment was conducted in the same manner as in Example 5 using the catalysts listed in Table 1, and the results were as shown in Table 1.

Example 7 A combustion experiment was conducted under the same conditions as in Example 5 using the catalyst listed in Table 1 exposed to an electric furnace at 1000''C in air for 200 hours. The results are shown in Table 2. That's right.

[Brief explanation of the drawing]

FIG. 1 is a distribution curve diagram of platinum in the catalyst according to the present invention.

Claims (2)

[Claims] (1) In a catalyst body in which activated alumina and platinum are coated and supported on a monolithic carrier for catalytic combustion of a combustible mixed gas consisting of vaporized gas of kerosene fuel and air, the amount of supported activated alumina is 20-20 per liter of carrier
0 g, the amount of platinum supported is 0.1 to 2 g per liter of the carrier, and furthermore, the amount of platinum supported is 40% or more of the total amount of platinum supported within 5 μm from the outermost layer of the coating layer, and 10 μm from the outermost layer.
A catalyst for combustion, characterized in that 60% or more of the total amount of platinum supported within m. (2) The combustion catalyst according to claim 1, characterized in that dinitrodiaminoplatinic acid is used as the raw material for the platinum.