JPS58183944A - Catalyst body for high temperature catalytic combustion - Google Patents

Abstract

PURPOSE:To suppress the abrupt lowering of activity of an oxidation catalyst at a high temp., by coating a carrier containing Al2O3 with CaO.ZnO2 composite oxide prior to supporting the oxidation catalyst to prevent the alloying of the oxidation catalyst and Al2O3 in the carrier. CONSTITUTION:A heat resistant inorg. honeycomb structure having plural small pores pierced to a definite direction and containing Al2O3 as a component is used as a carrier 1 and an oxidation catalyst is supported by the carrier 1. In this catalyst body 5, prior to supporting the oxidation catalyst 4, the carrier 1 is coated with CaO.ZrO2 composite oxide containing 15-28% CaO as shown by the numeral 3 to prevent the alloying of the oxidation catalyst 4 and Al2O3 in the carrier. As the result, the abrupt lowering in the activity of the oxidation catalyst is suppressed even at a high temp. of about 1,400 deg.C and the catalyst body with long life can be obtained.

Description

[Detailed description of the invention] The present invention uses a heat-resistant inorganic nicum structure as a carrier,
The present invention relates to a catalytic combustion catalyst body having an oxidation catalyst supported thereon.

A catalytic combustor uses the reaction heat generated by causing a catalytic oxidation reaction by sending a premixed gas of various gaseous fuels or vaporized liquid fuel and combustion air onto an oxidation catalyst. It is. As a result, the surface temperature of the catalyst became quite high, creating extremely harsh conditions for the catalyst itself.

Most conventional products contain Mu 1203 as a component in the heat-resistant inorganic honeycomb structure used as a carrier. Since the oxidation catalyst is directly supported on such a carrier, when the catalyst body becomes high temperature due to the reaction heat generated during catalytic combustion, the oxidation catalyst in the carrier 120s
The drawback was that the oxidation catalyst and the oxidation catalyst formed a spinel structure, resulting in a rapid decline in activity as an oxidation catalyst.

The catalyst body for high-temperature catalytic combustion according to the present invention can suppress the above-mentioned drawbacks, and prevents spinel formation of the oxidation catalyst and Mu e205 in the carrier, suppresses a decrease in the activity of the oxidation catalyst, and achieves stability and efficiency. The purpose of the present invention is to provide a catalyst body for high-temperature catalytic combustion that has a good oxidation reaction, produces clean exhaust gas, and has a long life.

In order to achieve the above object, the catalyst body for high-temperature catalytic combustion according to the present invention contains CaO-Zr containing 16 to 28% CaO in advance on a carrier containing Mu120sf as a component.
The basic structure was that an O2 composite oxide was coated and an oxidation catalyst was supported on it. According to this configuration, by supporting the CaO-Zr0z composite oxide on the carrier in advance,
This prevents the carrier from coming into contact with the oxidation catalyst, and prevents the oxidation catalyst from forming a spinel with the mucus 71203 in the carrier. Furthermore, CaO-ZrO2 containing 16-28% CaOf
The composite oxide maintains a cubic crystal system at about 20oO°C,
Since it is in a stable state and does not undergo a phase change, C
Even if high-temperature catalytic combustion of about 1600° C. is performed on a catalyst body coated with an aO-ZrO2 composite oxide and an oxidation catalyst supported thereon, there is no fear of thermal destruction of the catalyst body.

Examples of the catalyst body for high-temperature catalytic combustion according to the present invention will be described below with reference to the drawings.

Figure 1 shows an embodiment of the catalyst body for high-temperature catalytic combustion according to the present invention.
The carrier 1 is formed into a two-cam shape and has a large number of square small holes 2.

Figure 2 shows that 16-28% CaO is added to the carrier 1 shown in Figure 1.
FIG. 2 is a schematic diagram showing a partial vertical cross section of a catalyst body 5 coated with a CaO-ZrO2 composite oxide layer 3 containing f and on which an oxidation catalyst 4 is supported. In this case, mullite was used as the heat-resistant inorganic material, but α-alumina, cordierite, etc. may also be used, and the shape of the small holes 2 is also square.

It doesn't matter if it's circular, triangular, or hexagonal.

An application example of a liquid fuel catalytic combustion device using a catalyst body for high-temperature catalytic combustion according to the present invention is shown in FIG. 3, and its structure and operation will be explained.

An air introduction lower appears at the bottom of the bottomed cylindrical fan goo 76, and the shaft 9Fi of the fan motor 8 fixed to the bottom of the fan case 6 is connected to the center line of the fan case 6 from the air intake introduction lower. It is installed inside the fan case 6. The fan motor 8 is covered by a motor case 11 having an air intake port 10i. Fan 1 on shaft 9
3 and guide blades 13 are fixed to the fan case 6 and are alternately provided in multiple stages. On the other hand, at the other end of the fan case 6 is a fixed plate 1 having an air port 14 in the center.
6 is fitted, and a vaporization premixing cylinder 1 is attached to the outside of the fan case 6 through a backing 16, and a sheathed heater 1 is mounted on the side wall of the vaporization premixing cylinder 17 near the fixed plate 16.
8 are buried. Further, a combustion tube 19 is connected in front of the vaporization premix tube 17, and a resistance plate 20 made of wire mesh or punching metal is installed inside the combustion tube 19, and a rectifying effect is performed via a spacer 21 in front of the resistance plate 20. A baffle plate 22 and a catalyst body 6 according to the present invention are installed in this order. Further, a space surrounded by the resistance plate 20 and the fixed plate 16 serves as a vaporization premixing chamber 23, and a spark plug 24 is installed in the combustion cylinder 19 between the rectifying plate 22 and the catalyst body 6.

On the other hand, at the tip of the rear shaft 9 that penetrates the fan case 6 and faces into the vaporization premixing chamber 23, there is a circular trapezoidal cone 26 whose diameter becomes dog-shaped toward the fan motor 8 side toward the tip υ, and a rotary plate 26. , a mixing plate 27 having small stirring blades at the peripheral end is fixed one after another. Further, the oil supply pipe 2aFi is installed so as to penetrate the fan case 6 from the side and open above the cone 25.

Next, the operation of the liquid fuel catalytic combustion device having the above configuration will be explained.

When the sheathed heater 18 is energized and the side wall of the vaporization premix cylinder 17 reaches a predetermined temperature, the fan motor 8 and the electromagnetic pump (not shown) are energized and the supply of air and liquid fuel is started. The liquid fuel is sent onto the rotating cone 26 through the fuel supply pipe 28, and when it reaches the rotary plate 26 through the taper of the cone 26, it is scattered in the circumferential direction by the rotational force, maintaining a constant temperature state. It comes into contact with the wall surface of the vaporization premix cylinder 17 in which it is placed and is vaporized. On the other hand, the intake port 10 is
The air taken in is passed through the intake introduction lower and sent into the vaporization premixing chamber 23 from the air port 14, where it is uniformly mixed with the vaporized liquid fuel gas by the action of the mixing plate 27 to become a premixed gas. After the premixed gas passes through the resistor plate 2o and the rectifying plate 22, it is ignited by the spark plug 24, which generates a spark when energized. At the initial stage of ignition, a blue flame is formed in front of the baffle plate 22 to cause flame combustion, and the temperature of the catalyst body 6 is raised to the activation temperature necessary for catalytic combustion by radiant heat from the flame and heat transfer from the combustion tube 19. reach up to. Thereafter, the blue flame is extinguished and catalytic combustion is performed on the catalyst body 6. The surface temperature of the catalyst body 6 at this point is s
The premixed gas is completely oxidized by the catalytic oxidation reaction, and the catalytic oxidation reaction maintains a steady state.

Measured data specifically showing the effects of using the catalyst body for high-temperature catalytic combustion according to the present invention is shown in FIG. 4 below.

The sample used in this case was prepared by crushing a cordierite material having a no-nicum structure as shown in FIG. Sample (1
) is one in which NiOf is supported as an oxidation catalyst on the above carrier particles, and sample (2) is one in which NiOf is supported on the above carrier particles.
8% C&O'! ! After coating the il-containing CaO-ZrO2 composite oxide to about 1oW% based on the carrier weight,
The oxidation catalyst NiOf is supported. Oxidation catalyst NiO
The supported amount is the carrier weight for sample (1), and the supported amount of C for sample (1).
Based on the weight of the carrier after coating with the aO-ZrO2 composite oxide, it was set to contain 2W% of weight. An impregnation method using an aqueous nickel nitrate solution was used to support NiO. The sample was fired in air for 12 hours at e o o 'C.
00' Baked in air for 0.4 hours.

The experimental method was to place a fixed volume of the sample in a reaction tube, pulse-wise (instantaneously) inject CH4 conversion mixed gas diluted with He gas into the reaction tube, and perform a catalytic oxidation reaction on the sample. The gas composition after the reaction is analyzed using a gas chromatograph. The reason why CH4 conversion ratio mixed gas iHe gas is diluted to form a reaction gas is to prevent CH4 and 02 from undergoing a gas phase reaction, that is, an oxidation reaction without using a catalyst.

The products of the reaction were CO and C02.

The total amount of unreacted CH4, generated CO1 and generated CO2 is Z011
4. “CQ.

:"002, CH4 conversion rate X ama (in
011%) is (t+o+”002) x 1oo
7 (represented by x(3(, H4 in +x), CO2 yield yield O2 (1401%) is !co2X 100 /
It is expressed as (Xco + jeco2+ 0ecaa). In other words, the CO2 yield is determined by how much of the raw material CHa is CO2.
2, and can serve as a standard for determining whether the catalyst has complete oxidation activity.

As can be seen from the experimental results in Figures 4 and 4B, sample (2), in which the carrier was pre-coated with CaO-ZrO2 composite oxide, had a higher CH4 conversion rate and CO2 yield than sample (1). However, there is an extremely large difference in the CO2 yield rate. That is, in the case of sample (1), spinelization occurs between the oxidation catalyst and the p205 in the carrier, and this alloying causes a considerable decrease in the CH4 conversion rate, but also a significant decrease in the CO2 yield. , it can be seen that the complete oxidation ability is significantly degraded. In this manner, by coating the carrier with the CaO-ZrO2 composite oxide in advance, it is possible to prevent the oxidation catalyst from turning into a spinel with the rubber 1205 in the carrier, and the ability of the oxidation catalyst can be fully exhibited.

The catalyst body for high temperature catalytic combustion according to the present invention has the following effects.

A heat-resistant inorganic material containing 120 sf of silica as a component is used as a carrier, and 16 to 28% CaOf is preliminarily applied before supporting the oxidation catalyst.
By coating the contained CaO-ZrO2 composite oxide, it prevents alloying of the oxidation catalyst with Mu-1203 in the carrier, suppresses the rapid decrease in activity of the oxidation catalyst even at high temperatures of about 1000°C, and provides a long service life. It can be used as a catalyst.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a carrier according to an embodiment of the invention, and FIG. 2 is a perspective view of a carrier according to an embodiment of the present invention.
Figure 3 is a partially enlarged vertical cross-sectional view of a catalyst body for high-temperature catalytic combustion manufactured from the carrier shown in the figure, and Figure 3 is a vertical cross-section of an example of an application in which the catalyst body for high-temperature catalytic combustion shown in Figure 2 is installed in a liquid fuel catalytic combustion device. Front view, Figure 4. B is a graph showing the effect of the catalyst body for high temperature catalytic combustion according to the present invention. 1...Carrier, 2...Small hole, 3...
...CaO-Zr0z composite oxide coating layer, 4...
- Oxidation catalyst, 6...Catalyst body for high temperature catalytic combustion. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 41 β 8
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i1=, kG#8: qomffl-at
-isu E QOO'c, Q6θ'
c, rooo℃・WEη゛su string A C custom, %

Claims (3)

[Claims] (1) In a catalyst body formed by using a heat-resistant inorganic honeycomb structure as a carrier and having a large number of small pores penetrating in a certain direction and containing Mu 1203 as a component, and supporting an oxidation catalyst on the carrier, oxidation is performed. 16-28% on the support before supporting the catalyst.
A catalyst body for high-temperature catalytic combustion which is coated with a (aO-Zr02) composite oxide containing CaO to prevent alloying of the oxidation catalyst and the silica 1203 in the carrier. (2) Claim 1 in which ceramics such as α-alumina, Cope 1 yellowite, mullite, mullite-zircon, mullite-α-alumina, alumina silicate, and aluminum-titanate are used as the material of the support. The catalyst body for high-temperature catalytic combustion described above. (3) Ni, Go, F as a oxidation catalyst
The catalyst body for high-temperature catalytic combustion according to claim 1, which uses a combination of at least one type of transition metal oxides such as E, Mn, Cu, and Zn.