JPH0394834A - Carrier for catalyst - Google Patents

Abstract

PURPOSE:To obtain a catalyst carrier having high thermal shock resistance, superior durability and high strength at high temp. by dispersing fireproof metal fibers each coated with a double layer consisting of an inner Nb layer and an outer superalloy layer in an Ni- or Co-based superalloy substrate. CONSTITUTION:Each of fireproof metal fibers such as tungsten fibers is coated with a double layer consisting of an inner Nb or Nb alloy layer and an outer Fe-based superalloy layer and the coated fibers are dispersed in an Ni- or Co- based superalloy substrate to obtain a heat resistant composite body as a catalyst carrier. This carrier has high thermal shock resistance, superior durability and high strength at high temp.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Application in Industry 7) The present invention relates to a carrier for a catalyst, and particularly to a carrier for a catalyst that is resistant to thermal shock, .
The present invention relates to a catalyst carrier made of a heat-resistant composite material having high strength at high temperatures.

(Prior Art) Recently, from the viewpoint of energy saving and resource saving, it has been desired to burn fuel at as high a temperature as possible in a gas combustor for driving a gas turbine or the like.

In order to meet this demand, conventional methods have been adopted in which a mixture of fuel and air is ignited and combusted using an ignition means such as a spark plug. However, in this case, the temperature exceeds 2000°C locally in the combustor,
There was a problem that a large amount of nitrogen oxide (NOx) could be generated from this part, causing environmental pollution.

In order to solve these problems, a catalytic method has been proposed in which a mixture of fuel and air is combusted using a catalyst.

This combustion method enables uniform combustion of lean fuel and can raise the combustion temperature to around 1,500 degrees Celsius, which is the upper limit temperature at which no NOx is generated, so it is seen as promising for application in gas combustors, etc. .

The catalyst carrier used in this catalytic combustion method is cordierite ceramics (2MgO・2' AI2 0
3.5Si02) is well known. However, this cordierite ceramic is susceptible to thermal shock and has the problem of cracking and fracture after being subjected to several thermal cycles.

Recently, from this point of view, Feclap, which is resistant to thermal shock and has excellent oxidation resistance, has been used as a catalyst carrier for purifying automobile exhaust gas.
(FeCrAjl alloy) is used. However, the heat resistance temperature of this Feclaroy is about 900° C., and there is a problem that the high temperature strength is low in a temperature range higher than this, and it cannot be used as a catalyst carrier.

(Problems to be Solved by the Invention) As mentioned above, conventional cordierite ceramic catalyst carriers are susceptible to thermal shock and do not have sufficient durability, and Feclaroy catalyst carriers have a heat resistance temperature of 900°C. That's about it, and beyond that. At a temperature of 12, there was a problem that the high temperature strength was insufficient and it could not be used.

The purpose of the present invention is to have high resistance to thermal shock and excellent durability.
The object of the present invention is to provide a catalyst carrier that has high strength at high temperatures.

[Structure 1 of the invention (Means and effects for solving the problems) The present invention provides a niobium layer made of niobium or a niobium alloy on the outer periphery and an iron base covering the niobium layer in a nickel-based or cobalt-based superalloy base. This is a catalyst carrier characterized in that it is made of a heat-resistant composite body in which refractory metal fibers covered with a double layer of a superalloy layer made of a superalloy are arranged. Further, the catalyst carrier of the present invention has a structure, for example, a honeycomb structure, in which a plurality of mesh sheets made of heat-resistant composite wires made of this heat-resistant composite are laminated.

The catalyst carrier of the present invention has a structure in which it is disposed in a nickel-based or cobal-h-based superalloy substrate that has excellent high-temperature oxidation resistance in order to protect refractory metal fibers that have excellent high-temperature strength from high-temperature oxidation. Consists of heat-resistant composite.

As the catalyst carrier of the present invention, a certain refractory metal fiber made of tungsten, molybdenum, tantalum, or an alloy thereof can be used, but it is practically preferable to use a tungsten alloy. In addition, adding rhenium (Re) from 3 to 30vt% to improve the high-temperature strength characteristics of the W wire cannot be expected to be effective if the content is less than 3vt%, and if it exceeds 30vt%, the Strength decreases.

Furthermore, the strength of the W wire can be similarly greatly increased by impregnating the W wire with thorium oxide (ThO2), potassium, silicon, or aluminum by doping or the like. In the case of Th02, this content is 0.5vt%
It is in the range of ~8vz%. Also, K, Si or Aj
l! When used alone or in combination, the content is 50
It ranges from ppm to 3θOppm. Addition of ThO2 is expected to strengthen dispersion, but if the amount added is less than 0.5 wt%, this effect cannot be expected. If it exceeds vt%, it will actually become a defect. K, Si, 1? However, it cannot be expected to be outside the range of 50 to 300 ppm because it causes precipitation at grain boundaries and provides resistance to recrystallization. This tungsten alloy is suitable because it hardly causes recrystallization, which causes strength deterioration, at high temperatures of 1000° C. or higher.

In addition, by covering the periphery of this refractory metal fiber made of W with a double layer of an Nb layer and a superalloy layer, it is possible to prevent the reaction at high temperatures with the nickel-based or cobalt-based superalloy ε-resistant metal fiber that is the matrix. This can prevent deterioration in the strength of the refractory metal fiber. This Nb layer has a coefficient of thermal expansion between ψ between the coefficient of thermal expansion of the refractory metal fiber and the coefficient of thermal expansion of the nickel-based or cobalt-based superalloy, so it prevents thermal fatigue due to the difference in thermal expansion coefficient and resists thermal shock. Improve characteristics.

The nickel-based superalloy substrate in the present invention includes, for example, 10 to 40 vt% C r s 5 to 20 vt%.
AN, 0.3~! ．． ．． 5wt% Y and balance N
i to some NiCr/JY alloy or to ~40wt%
of Cr, 5 to 20 vt% AII, 0.3 to l.
5wt% Y, 5~30wt% CO, O~30
NiCoCrA from wt% Fe and balance Ni,
RY alloy is used (.1).Also, a cobalt-based superalloy substrate is used, and 5 to 35 vt% of Cr, 5-
20vt% AJ, 0.3~I. ．． 5wi% Y,
Kobal L consisting of 0-20wt% Nj and the balance C0
This is where you can use basic supercompany.

Furthermore, the iron-based superalloy for the coated layer ε of the reduced metal fibers may be any iron-based superalloy containing 20% or less of aluminum by weight. For example, lO ~ 30 wt% C
v, 5-20vt% Ad! , 0.3 ~1
．． Some FeCrAfJY from 5vl% Y and balance iron
Alloys can be used.

The catalyst carrier of the present invention is composed of a heat-resistant composite made of refractory metal fibers covered with a niobium layer and a supermetallic layer, which increases the high-temperature strength of a superalloy, so that it can withstand temperatures of -12 to 1000°C. It has sufficient high-temperature strength (7).Moreover, it has excellent thermal shock resistance when subjected to repeated heat loads at room temperature and temperature ε, since it contains the heat resistance of gold.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, 1. 1a diameter 0 containing 7vl% ThO2
．． A 3 mm W wire was fixed on a gold plate, and while rotating, Nb was applied to the surface of the W wire by plasma spraying in a low-pressure atmosphere. ．． The coating was applied to a thickness of 0.3m+*. Subsequently, FeCrA was deposited on the Nb layer by plasma spraying in a similar low-pressure atmosphere.
The fiY alloy was coated to a thickness of 0.03 mm, and the NiCoCrAjlY alloy was coated with an O. Coated with a thickness of l+e+m, W/Nb/Fe
A composite material wire having the structure C rAj7 Y/N i CoC rAll Y was fabricated.

As shown in the plan view in Fig. 1 and the side view in Fig. 2, this composite material wire 0) was knitted to produce a net-like sheet (2), and 20 sheets of this sheet were placed between them. A catalyst carrier (3) having a honeycomb structure was produced by stacking the layers with a brazing filler metal sandwiched therebetween, and heat-treating the stacked body in a vacuum at 1100° C. for 10 minutes.

This catalyst carrier is popular, and when its high-temperature tensile strength at 1100°C was measured after heating at 1200°C for 200 hours, it had a strength of 60 kg/2. From this measurement result, this catalyst carrier shows that even when heated at high temperature for a long time,
After obtaining sufficient high-temperature strength, the strength ε was found. Further, it was found that this catalyst carrier was not oxidized even when subjected to heat treatment at 1200° C. for 500 hours in the air, and had excellent oxidation resistance.

Furthermore, the gap between room temperature and 1200℃ was rapidly heated and rapidly cooled for 1 time.
It was found that even when subjected to repeated thermal loads of 0.00 or higher, no deformation or cracks occurred, indicating that the material had excellent thermal shock resistance.

A catalyst can be obtained by carrying an oxide such as nickel or cobalt, or a catalyst such as platinum or palladium on this catalyst carrier.

Effects of the Invention] As mentioned above, according to the present invention, it is possible to provide a U-body for catalysts that is resistant to thermal shock, has excellent durability, and exhibits high strength at high temperatures. .

[Brief explanation of drawings]

FIG. 1 is a plan view of a catalyst carrier according to an embodiment of the present invention;
FIG. 2 is a side view of the catalyst carrier of FIG. 1. 1... Composite material wire, 3... Catalyst carrier. 2... Reticulated sheet,

Claims (2)

[Claims] (1) In a nickel-based or cobalt-based superalloy substrate,
A niobium layer consisting of niobium or a niobium alloy on the outer periphery, and a superalloy layer consisting of an iron-based superalloy covering this niobium layer.
A catalyst carrier characterized by being made of a heat-resistant composite material in which refractory metal fibers covered with multiple layers are arranged. (2) in a nickel-based or cobalt-based superalloy substrate;
A niobium layer consisting of niobium or a niobium alloy on the outer periphery, and a superalloy layer consisting of an iron-based superalloy covering this niobium layer.
A catalyst carrier characterized in that it has a structure in which a plurality of mesh sheets made of a heat-resistant composite wire made of a heat-resistant composite wire covered with multilayered refractory metal fibers are laminated.