JPS62114650A - Combustion catalyst body - Google Patents

Abstract

PURPOSE:To obtain the titled catalyst body improved in the efficiency of quantity of radiant heat, by supporting at least one metal selected from a platinum group metals and zirconium oxide by an inorg. fibrous carrier. CONSTITUTION:At least one metal selected from a group (a) consisting of plati num, palladium and rhodium and zirconium oxide (b) are supported by an inorg. fibrous carrier (e.g., a laminate of alumina fibers) with a fiber diameter of 0.5-20mum to obtain a combustion catalyst body. The optimum support amount of the components (a), (b) in the catalyst body to the inorg. fibrous carrier is adjusted so that the component (a) is 0.1wt%, pref. 0.3-3wt% and the compo nent (b) is 0.1-30%, pref. 1-10wt%. If this catalyst is used in a catalytic combuster, the gaseous fuel introduced from a gas supply passage 4 is diffused up to the surface layer part of the catalyst body 1. An entire amount of neces sary air is supplied to the catalyst body from the front surface thereof and the fuel is perfectly burnt at the uppermost surface part of the catalyst body at low temp. and quantity of heat is radiated in highly efficient manner per unit of input heat.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustion catalyst body. More specifically, the present invention relates to a combustion catalyst used in a catalytic combustor that completely burns gaseous fuel or vaporized liquid fuel flamelessly and at low temperatures on the catalyst to generate thermal radiation rich in far-infrared rays.

Conventional technology An example of the configuration of the above catalytic combustor is shown in FIG.

1 is a catalyst body, 2 is a protective wire mesh, 3 is a heat insulating material, and 4 is a gaseous fuel supply path.

The gaseous fuel introduced through the gas supply path diffuses to the surface layer of the catalyst body made of an inorganic fiber laminate, while the entire amount of air necessary for catalytic complete combustion is supplied from the front side of the catalyst body by natural diffusion, At the outermost layer of the catalyst, complete combustion occurs at a low temperature in a flameless state, and the heat of combustion is used as far-infrared rays, which has higher thermal efficiency than infrared rays.

Various types of catalyst bodies have been proposed for use in such catalytic combustors.

As the carrier, a laminate or low-density mat of inorganic fibers having micropores is used, and specific inorganic fibers include alumina, zirconia, titania, thoria,
Fibers made of alumina-silica, silica, zirconia-silica, etc. In addition, platinum group metals such as platinum, palladium, and rhodium are used as catalytic active components, and nickel, cobalt, chromium, etc. are used as cocatalysts, and these are supported on the above-mentioned carriers and used as catalysts (Japanese Patent Application Laid-Open No. 51-83088, JP 56-62542, JP 58-149-18, JP 57-23540,
(See Special Publication No. 58-15012, Special Publication No. 58-20306, etc.)

Problems to be Solved by the Invention However, the amount of radiated heat in a catalytic combustor using such a conventional catalyst body is approximately 50 inches per human calorific value, which is approximately twice that of a conventional infrared combustor. Although it is said to be approximately twice as much as an electric far-infrared heater in terms of negative energy, there are still problems with the efficiency of its radiant heat that needs to be improved.

Therefore, an object of the present invention is to provide a combustion catalyst used in a catalytic combustor that completely burns gaseous fuel or vaporized liquid fuel on a catalyst body without flame and at low temperature, thereby emitting thermal radiation rich in far-infrared rays. The object of the present invention is to provide a combustion catalyst that has a high amount of radiated heat per unit of human heat and has a distribution of thermal radiation in the far infrared region.

A means to solve the problem is that the combustion catalyst of the present invention is made by supporting at least one metal selected from the group consisting of platinum, palladium, and rhodium and zirconium oxide on an inorganic fiber carrier. This is a characteristic feature.

The most distinctive feature of the present invention is that zirconium oxide (zr0
2). Note that the term "supported" as used in the present invention refers to a state in which a metal or metal oxide is dispersedly supported on a carrier, or a state in which the metal or metal oxide is completely or incompletely coated.

The present inventors have discovered that by supporting zirconium oxide, gaseous fuel or vaporized fuel burns on a catalyst layer made of platinum group elements, and the heat of combustion radiates far infrared rays from zirconium oxide, which is then transferred to other parts. The inventors discovered that the far-infrared rays were further emitted and the heating effect was increased, and that even when the surface temperature of the fibrous catalyst body was low, a greater far-infrared radiation effect could be obtained, and the present invention was completed. .

The amount of zirconium oxide supported is usually 0.1 to 30% by weight, preferably 1 to 10% by weight, based on the inorganic fiber carrier. If the supported amount is too small, such as less than 0.1% by weight, high far-infrared radiation efficiency cannot be achieved, whereas if it exceeds 30% by weight, the ignition temperature of the catalyst increases and the combustion activity deteriorates, which is undesirable.

Still in the present invention, 0.1 of zirconium oxide
~20% by weight, preferably titanium oxide (TiO2), chromium oxide (Cr203) within the range of 0.5~5% by weight.
), nickel oxide (NiO), and iron oxide (Fe203).

The amount of at least one metal selected from the group consisting of platinum, palladium, and rhodium supported is 0.1% by weight or more, preferably 0.3 to 3% by weight, based on the inorganic fiber carrier. Furthermore, some of these platinum group metals include nickel,
It is also possible to substitute metals such as cobalt and chromium.

The inorganic fiber carrier used in the present invention is generally a laminate, molded product, woven cloth, or paper of inorganic fibers used in this field. Examples of the inorganic fiber include alumina, zirconia, titania, Doria,
It is made of alumina-silica, silica, zirconia-silica, alumina-silica-magnesia, etc., and its fiber diameter is 0.5 to 20 μm, preferably 1 to 1 μm.
m is used.

Particularly preferred are inorganic fibers made of alumina, alumina-silica, alumina-silica-magnesia, titania or silica, and these have a larger specific surface area than zirconia or zirconia-silica fibers, so platinum group metals are preferred. When supported, it has good dispersibility and excellent combustion activity. In addition, when a platinum group metal is supported on an inorganic fiber carrier made of pure zirconia or zirconia-silica that does not support zirconium oxide, its dispersibility is poor and the combustion activity is lower than that when an alumina-based inorganic fiber carrier is used. Although inferior, when zirconium oxide and platinum group metal are supported on this zirconia-based inorganic fiber carrier, the dispersibility of the platinum group metal is improved and the combustion activity is also excellent.

As a method for manufacturing the combustion catalyst body of the present invention, ordinary means are employed. For example, a solution in which water-soluble salts of platinum group metals and zirconium are dissolved in water is supported on an inorganic fiber carrier by a dipping method, an impregnation method, a spray drying method, etc., and then the finished catalyst is obtained by drying and firing. be able to.

The platinum group metal and zirconium oxide may be supported in the same order, the platinum group element may be supported first and then the zirconium oxide is supported, or vice versa. In addition, especially when supporting zirconium oxide, the fiber carrier may be immersed in the form of an aqueous solution of nitrate, acetate, oxalate, or chloride, or a powdered oxide such as zirconium oxide may be immersed in the form of a slurry. It is also possible to directly coat the coated material.

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

Example 1 An inorganic fiber carrier having an average fiber diameter of about 3 μm, a glue strength of 5 weight percent, and consisting of 95 weight percent alumina was immersed in a zirconium nitrate solution. This fibrous carrier was dried at 150°C and then calcined in air at 500°C for 2 hours. Next, 0.5% by weight of platinum and Z
2.7% by weight of rO2 was supported.

Example 2 The same carrier as in Example 1 was immersed in a solution of palladium nitrate and zirconium nitrate, and then 0.1% by weight of palladium and ZrO were added in the same manner as in Example I.

As a result, 1.35% by weight was supported.

This was further immersed in a solution of chloroplatinic acid and titanium tetrachloride to support 0.5% by weight of platinum and 1.35% by weight of TiO2.

Example 3 An inorganic fiber carrier having an average fiber diameter of about 1.7 μm and consisting of 15% by weight of 79% and 85% by weight of alumina was immersed in a solution of zirconium nitrate and chromium nitrate. In the same manner as in Example 1, 5.4% by weight of ZrO and 2.7% by weight of Cr, 03 were supported, and then 0.8% by weight of Pt was supported by dinitrodiaminoplatinum and rhodium nitrate solution. , 0.02% by weight of Rh was supported.

Example 4 A woven sheet of alumina-silica-magnesia fibers was coated with a slurry of zirconium nitrate, nickel nitrate, and iron nitrate, and then immersed in a dinitrodiaminoplatinum solution to obtain 0.5 weight of platinum in the same manner as in Example 1. %, ZrO2
as 4.055% by weight NiO and as 0.67% by weight,
0.67% by weight of Fe2O3 was supported.

Comparative Example 1 0.5% of FZ was supported as platinum in the same manner as in Example 1 except that the sample was not immersed in the zirconium nitrate solution.

Example 5 The combustion catalyst bodies obtained in Examples 1 to 1 and Comparative Example 1, 20 m long, 30 CIll wide, and 10 thick, were each held in the surface diffusion type combustor shown in FIG. k
LPG corresponding to cal/crA-hr was passed through and ignited with a heater. After ignition, the heater was turned off and the infrared radiation characteristics of the catalyst body at a surface temperature of 160°C were measured, and the results are shown in Table 1. Here, the relative radiant intensity indicates the radiant intensity (%) relative to a black body.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the configuration of a catalytic combustor. Patent applicant: Nippon Shokubai Chemical Co., Ltd. Figure 7

Claims (1)

[Claims] (1) A combustion catalyst comprising an inorganic fiber carrier supporting at least one metal selected from the group consisting of platinum, palladium, and rhodium and zirconium oxide.