JPS5820311B2 - Combustor catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst body for a combustor, and in particular, an object of the present invention is to provide a catalyst body for a combustor that has good temperature distribution, high strength of the catalyst body, and a large amount of heat load.

Various methods have been proposed to produce catalyst bodies for combustors, in which fine particulate silica or alumina is attached to heat-resistant fibers such as asbestos, glass fiber, and diatomaceous earth, and then platinum group metals are supported as catalysts. The main focus of these methods is to firmly adhere platinum group metal catalysts to fibers, which serve as catalyst carriers, and in cases where glass fibers are used, the surface of the glass fibers is corroded by treatment with a concentrated alkaline solution, and then the catalyst is removed. There are also documents that support this.

In such a catalyst body for a combustor, the fibers that are the catalyst carrier and the catalyst are firmly attached, but since the catalyst carrier is cotton-like or felt-like and flexible, even if the fibers and the catalyst are not firmly attached. Even if the catalyst carrier is deformed or damaged by external impact, the surface of the catalyst easily peels off, and once the surface of the catalyst peels off, the catalyst carrier is deformed or damaged, making it difficult to repair. Smooth catalytic combustion cannot continue.

For this reason, it was necessary to protect the surface of the catalyst body with a wire mesh, or to take special measures to attach the catalyst body.

Furthermore, many cotton-like or felt-like catalyst bodies have almost no ventilation resistance, so they are easily affected by the specific gravity of the fuel gas. For example, when using butane gas with the catalyst combustion surface upright, the temperature of the combustion surface There were drawbacks such as unevenness between the top and bottom, and in addition, the protective metal fittings of the catalyst absorbed infrared rays, resulting in a significant drop in radiation efficiency.

The present inventors have conducted numerous studies to eliminate the various drawbacks described above, and have completed a novel combustor catalyst body as described below.

That is, the present invention provides a molded article io of ceramic fiber.

After supporting 10 to 100 parts by weight of fine silica on each part by weight, it is dried at a temperature of 100°C or less, and then fired at a temperature of 250 to 600°C, and platinum is coated on one side of the fired body. This is a catalyst body for a combustor, characterized in that it supports a group metal of 0.5 to 5 jj/m.

100 to 100 parts by weight of finely divided silica is supported on 100 parts by weight of a molded body of ceramic fibers, and then dried at a temperature of 110°C or less. This refers to immersing a molded body in a solution of 4 to 30% by weight colloidal silica, or spraying it with a spray device, and then drying it at a temperature of 110° C. or lower.

Ceramic fibers usually contain 50% each of silica and alumina.
Although it contains about % by weight, it is also possible to use a material with a high silica content or a high alumina content to form a molded body.

The shape of the ceramic fiber molded body is generally a plate shape, but it can be made into any shape such as a wave shape or a cylindrical shape depending on the purpose.

Particulate silica is obtained by impregnating colloidal silica and then drying it.

A colloidal silica solution is a colloidal solution in which fine particles of 1 to 100 mμ of silica are dispersed using water or alcohol as a dispersion medium.

Alternatively, ethyl orthosilicate may be used in a water or alcohol solvent and hydrolyzed with an acidic substance such as hydrochloric acid.

The amount of fine-grained silica supported on the ceramic fiber molded body is determined by the concentration of the colloidal silica solution and the number of immersion times, but by determining the relationship between the amount of fine-grained silica supported on a test piece in advance, Depending on the shape or size of the molded product, 10 to 100 parts by weight of fine-particle silica is supported on 100 parts by weight of the molded product.

If the amount of finely divided silica supported is less than 10 parts by weight per 100 parts by weight of the ceramic fiber molded body, the strength of the catalyst will be low and the gas passage resistance of the catalyst will be small, in other words, the influence of the specific gravity of the fuel gas will be reduced. 10
If it exceeds 0 parts by weight, not only will the cost increase due to the increased amount of silica, but the gas passage resistance of the catalyst will also increase, which means that the supplied gas pressure must be increased, and furthermore, it takes time to ignite the gas. Another disadvantage is that the catalyst becomes heavy.

Therefore, the amount of finely divided silica supported must be kept within the above range.

Furthermore, when drying a molded article of ceramic fibers carrying fine particulate silica, it should be carried out at a temperature of 110°C or less, particularly preferably at a temperature of 40 to 90°C,
If the temperature is raised and the product is rapidly dried, foaming may occur or the molded product may become distorted.

The molded body may be dried by any method such as hot air, infrared ray irradiation, reduced pressure, or dehumidified air.

Then, after firing at a temperature of 250 to 600°C, the dried ceramic fiber molded body is loaded with 0.5 to 5 g/m of platinum group metal on one side of the molded body. The firing method is generally to use high-temperature gas, but combustion exhaust gas may also be used, and methods such as infrared irradiation or high frequency may also be used, but dehydration is not possible at temperatures below 250°C. This is insufficient, and at temperatures above 600° C., the heat loss increases, which is uneconomical, and the activity of the catalyst decreases.

Therefore, the temperature range of 250 to 600°C is particularly preferably 30°C.
It refers to firing at a temperature range of 0 to 500°C and impregnating one side of the resulting fired body with an aqueous solution of a platinum group metal salt.

A 0.5 to 5% by weight aqueous solution of platinum group metal salt is used, and one side of the fired body is impregnated by brushing or spraying.Furthermore, the platinum group metal aqueous solution is placed in a shallow container and immersed. The platinum group metal is carried on the fired body at a ratio of 0.5 to 59/m.

In the catalyst body for a combustor of the present invention described above, fine particulate silica adheres to the space constituted by the ceramic fibers, and the fine particulate silica is preferably contained in a range of 10 to 100 parts by weight per 100 parts by weight of the ceramic fiber molded body. In addition to being supported by
The silica combines with the ceramic fibers that serve as the catalyst carrier, further increasing the strength of the combustion catalyst.

Furthermore, the catalyst body for a combustor of the present invention has a gas passage resistance greater than that of conventional cotton-like or felt-like catalyst bodies. It has the advantage of improved dispersion and therefore uniform temperature at the combustion surface.

In addition, the high strength of the catalyst means that there is no need for supporting metal fittings for the catalyst, protective wire mesh, or even gas distribution plates, which were conventionally required in the production of combustors, and in particular, there is no need for the wire mesh for the catalyst. is significant in that it increases the radiation effect of infrared rays.

Furthermore, since the surface of the catalyst body is hard, that is, the catalyst carrier has high strength and is strong against external impact and does not cause deformation or damage, so the catalyst is difficult to peel off. Even if the catalyst peels off, the catalyst carrier will be deformed or damaged. Therefore, the peeled area can be easily repaired by impregnating an aqueous solution of a platinum group metal salt in the above-described method.

As described above, the combustor catalyst of the present invention has a number of excellent properties not found in the prior art, and is of great industrial value.

An example of leprosy is shown below.

Ceramic fiber molded body (300 gm x 300 dragon x 20
After soaking 500 g of colloidal silica in an aqueous solution of colloidal silica with a concentration of 15% by weight, it was dried at 85°C in an electric constant temperature dryer, and then heated at 400°C in a city gas heating furnace. It was fired in

One side of the obtained fired body was impregnated with a 1.5% by weight aqueous solution of chloroplatinic acid by brush coating.

The weight of the combustor catalyst obtained by drying at 150°C is 8
The amount of platinum supported was 2 g/m.

The catalyst body for a combustor obtained in the above example was designated as A, and the catalyst body was obtained by directly immersing a ceramic fiber felt in an aqueous solution of 1.5% by weight chloroplatinic acid (platinum loading amount 2 g/m).
As B, both were reduced in a hydrogen gas atmosphere at 500°C, and then a comparative test was conducted using a combustor as shown in Figure 1. As a result, the results were as shown in Figures 3, 4, and Table 1. demonstrated its performance.

In FIG. 1, 1 is a combustor catalyst body, 2 is a metal container, and 3 is a fuel gas supply port provided at the center of the container 2.

In Figure 3, the combustor is set up as shown in Figure 2, and the butane gas is 0.
2 shows the temperature distribution on the surface of the catalyst when burning 056 m'/hr.

In addition, in FIG. 2, the top, middle, and bottom indicate the positions of the measurement points of the surface temperature of the combustor catalyst body.

Figure 4 shows the heat load and CO concentration in the combustion waste gas when butane gas is burned at 0.056 rn'/hr (according to the gas stove certification regulations of the Japan Gas Inspection Association).
Indicates the relationship between

Table 1 shows the compressive strength and pressure loss of catalyst body A and catalyst body B.

As is clear from the results, it was confirmed that the combustion method according to the present invention had a more uniform temperature on the combustion surface, lower CO concentration in the combustion waste gas, and higher compressive strength and pressure loss than the conventional method.

In addition, when the compressive strength was measured by varying the amount of fine-grained silica supported on the ceramic fiber molded body, it was confirmed that as the amount of fine-grained silica supported increased, the strength increased as shown in FIG. 5.

As is clear from the above results, it was confirmed that excellent performance such as high strength, uniform combustion, and less CO in the waste gas was obtained.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view showing an example of a combustor equipped with a combustor catalyst, and Figure 2 is a vertical cross-sectional view of the combustor shown in Figure 1 when it is placed upright.Measurement of the surface temperature of the catalyst. Figure 3 shows the distribution of the surface temperature of the catalyst when butane gas is combusted; Figure 4 shows the relationship between the heat load and the CO concentration in the combustion waste gas. , FIG. 5 is a diagram showing the relationship between the amount of supported particulate silica and the compressive strength. In addition, in the figure, 1 is a combustor catalyst body, 2 is a metal container,
3 indicates a fuel gas supply port.

Claims (1)

[Claims] 1. 100 to 100 parts by weight of fine particulate silica is supported on 100 parts by weight of a molded body of ceramic fibers, and then dried at a temperature of 110°C or less, and then dried at a temperature of 250 to 60°C.
1. A catalyst body for a combustor, characterized in that, after being fired at a temperature of 0°C, a platinum group metal is supported on one side of the fired body in an amount of 0.5 to 5 g/m''.