JPH02102738A - Porous iron catalyst carrier and production thereof - Google Patents

Abstract

PURPOSE:To obtain a catalyst carrier to which enough catalytic agents can be stuck with inexpensive iron powder, etc., by forming a three-dimensional network skeleton forming macropores and having a microporous coarse sintered surface. CONSTITUTION:Iron powder of about <=50mum average particle size is mixed with carbon and kneaded with a binder. The resulting kneaded material is stuck to a thermally decomposable network porous body as a skeleton, the porous body is removed by heating and self-reduction and sintering are carried out to obtain a catalyst carrier for a chemical apparatus, an apparatus for treating waste gas from an automobile, etc. The carrier is made of a porous sintered body having micropores 3 as well as macropores 1 formed by the iron skeleton 2. Enough catalytic agents such as noble metals and Cu group metals can be stuck to the carrier. The carrier is inexpensive.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a catalyst carrier used in the production of a catalyst.

More specifically, when a catalytic agent is applied to, for example, the ribs of the present catalyst carrier, it becomes a catalyst for use in chemical equipment or automobile waste gas treatment equipment.

[Conventional Technique vfI] A commercially available three-dimensional mesh ceramic porous body can be used as a catalyst by applying a catalyst agent to the bones. However, since this bone is smooth and slippery, it is difficult to apply a sufficient amount of catalyst, and ceramics are non-conductors.
It is difficult to apply the catalytic agent by electroplating, and the means for applying the catalytic agent are limited. Furthermore, since ceramics cannot be heated with electricity, for example, if a catalytic reaction is to be carried out at a high temperature, the passing fluid for the catalytic reaction must be separately heated to a high temperature, which requires a large-scale heating device.

JP-A No. 51-98690 describes roughening the surface of the skeleton by coating and baking metal powder on the surface of the skeleton of a metal three-dimensional porous material having a smooth surface, and applying a powder to the surface of the roughened skeleton. This is a catalyst coated with a catalytic agent.

However, the roughening of the skeleton surface in this method is due to electroless plating→
This is done by surface treatment → application of metal powder, etc. → baking.
Since the roughening process is complicated and the metal powder etc. are expensive, the catalyst carrier is also extremely expensive. Furthermore, even if a roughened layer is formed on the surface of a smooth metal skeleton, the bond between the skeleton and the roughened layer is weak, and the roughened layer is likely to peel off when the catalyst body is repeatedly heated and cooled.

The inventors of the present invention researched methods for manufacturing porous bodies at low cost, invented a porous iron body using inexpensive iron powder, etc., and filed a patent application in 1983.
-165884, Japanese Patent Application No. 165885, Japanese Patent Application No. 1978, Japanese Patent Application No. 1978, Japanese Patent Application No. 1978, and Japanese Patent Application No. 1983-21064.
A patent application was filed for No. 2.

The present inventors further conducted research on using these iron porous bodies as catalyst carriers, and completed the present invention.

[Problems to be Solved by the Invention] In other words, the present invention provides a method in which the bone portion has a three-dimensional network shape and forms macro-pores, and the bone portion has a rough sintered surface having micro-pores, and the catalyst agent is applied to the bone portion. A catalyst carrier that allows a sufficient amount of catalyst to be applied during coating due to the rough sintered surface, micropores, or the anchoring action of the catalyst that has penetrated into the micropores. Furthermore, since the catalyst carrier is electrically conductive, a wide range of methods for applying the catalyst agent, such as electroplating, are possible, and furthermore, the catalyst carrier can be heated to the desired temperature by direct current application or induction heating. Therefore, the present invention provides a catalyst carrier that can be applied to compact devices.

Further, the present invention provides an inexpensive catalyst carrier using iron powder or the like that is easily pulverized.

[Means for Solving the Problems] That is, the present invention is characterized in that (1) the iron rib portion forms macro pores of a porous body, and the iron rib portion is made of a sintered body having micro pores. (2) the iron skeleton is an iron back containing alloying elements;
The porous iron catalyst carrier according to (1) above, and (3) one or two selected from iron powder with an average particle size of 50 μ or less, iron oxide powder, and iron powder with an oxidized surface. By mixing the above or further carbon powder with an average particle size of 50μ or less,
A first step of producing a base material powder with a carbon and oxygen content of the following formula, and a second step of kneading the base material powder with a binder and applying it to the skeleton of the pyrolyzable network porous body. and a third step of heating the product of the second step to remove the pyrolyzable network porous material and further self-reducing sintering of the coated material to form macropores in the porous material at the back of the iron. A method for producing a porous iron catalyst carrier in which the iron skeleton is made of an iron sintered body having micropores.However, [C]: Carbon content (wt%) of the base material powder [0 ]
the oxygen content (wt%) of the powder for the base material, and (4) one or two types selected from iron powder and iron powder whose surface has been oxidized, with an average particle size of 50μ or less. A first step of producing a base material powder by mixing the above and a pyrolysis agent powder with an average particle size of 50μ or less, or carbon powder with an average particle size of 50μ or less, and a step of manufacturing the base material powder. A second step of kneading with a binder and applying it to the skeleton of the pyrolyzable network porous material; heating the product of the second step to remove the pyrolytic agent powder and the pyrolytic network porous material; and a third step of self-reducing sintering. The iron rib portion forms macro pores of a porous body, and the iron rib portion is made of a sintered iron body having micro pores.

This is a method for producing porous iron catalyst carriers.

(5) The above-mentioned (4), wherein the pyrolysis agent powder is a pyrolysis agent powder consisting of one or two or more selected from organic powders and carbonate powders.
(6) Self-reduction sintering is self-reduction sintering that is heated to 800 to 1200°C. (3) or (4) or (
5), the method for producing a porous iron catalyst carrier.

FIG. 1 is an enlarged view of an example of the bone portion of the porous iron catalyst carrier of the present invention. That is, in the catalyst carrier of the present invention, the iron skeleton 2 forms macropores 1, and the iron skeleton is formed of a sintered body having a large number of micropores 3. As will be described later, the catalyst carrier of the present invention is produced by kneading powder raw materials and applying the mixture onto the framework of a thermally decomposable network porous material 5, for example, a urethane foam, but the pore size of the urethane foam is selected. Depending on the situation, the pore size may vary from lOOμ to io+am
A through-hole type macro hole l can be formed.

As will be described later, the catalyst carrier of the present invention uses a powder raw material containing C or 0 or a powder raw material containing pyrolysis agent powder, but it does not contain CO gas or heat generated during the process of self-reducing sintering. Due to thermal decomposition of the decomposer powder, the pore size increases from 10 to 100.
Numerous micro-pores of μ are formed in the steel frame.

In the catalyst carrier of the present invention, the bone portion forms macro pores 1, and the bone portion is a sintered body with a rough surface and has micro pores 3, so that the catalyst agent is applied to the bone portion of the catalyst carrier. When painting,
Unlike the conventional method, for example, JP-A-51-98690, there is no need to further form a roughening layer on the surface of the bone, and the catalyst is applied directly to the bone. A sufficient amount of catalyst can be applied due to the rough surface, micropores, and the anchoring effect of the catalyst that has penetrated into the micropores.

The catalytic agent is applied to the bone with strong force, which prevents the catalytic agent from peeling off.

The catalyst agent applied to the catalyst carrier of the present invention includes:

White metals such as Pt, Pd, Rh, copper group such as cu*Ag+Au, Nd, Ca.

Rare earths such as La, Th, Mn, Cr, Ni, A O
, Ba, etc., or compounds thereof can be used. As for the method of applying the catalyst agent, since the catalyst carrier is electrically conductive, coating methods such as electroplating are also possible, and the catalyst carrier can be easily heated by passing electricity or by induction heating. The coating temperature can be arbitrarily selected, and drying, baking, heat treatment, etc. of the catalyst after coating can be performed more easily than before.

Further, since the catalyst body using the catalyst carrier of the present invention can be easily heated to a desired temperature by directly applying electricity or induction heating to the catalyst carrier, the present invention can be used, for example, as a carrier for a catalyst that performs a catalytic reaction at a high temperature. When used, unlike conventional methods, there is no need to separately heat the fluid for catalytic reaction, which simplifies the equipment and reduces operating costs.

Although the bone portion of the catalyst carrier of the present invention has a large number of micropores, since the matrix is made of strong iron, it has sufficient strength and toughness as a catalyst carrier. As will be described later, the catalyst carrier of the present invention is manufactured through the second step of coating the crosstalk material on the skeleton of the urethane foam, but by adjusting the shape of the urethane foam and the coating thickness of the crosswire material,
When formed into a thick skeleton, it becomes a porous catalyst carrier with even more sufficient strength and toughness.

The strength, toughness, corrosion resistance, etc. of the catalyst support bones can be further improved significantly by replacing the iron bones with alloy steel or stainless steel bones containing alloy elements.
For example, Mn, Ni, P, Cr, Mo, CtgA Q .

When one or more alloy components of Si are contained in molten iron and the iron powder obtained by pulverizing this is used as the iron powder in the first step described later, a catalyst consisting of bones containing these alloying elements can be obtained. The inclusion of the six alloying elements to obtain a support can also be achieved by, for example, adding and mixing the above-mentioned alloying powder to iron powder containing no alloying elements in the first step described later.

Next, a method for manufacturing a catalyst carrier of the present invention as set forth in claim (3) will be explained.

In the first step of the manufacturing method, iron powder, iron oxide powder, iron powder with an oxidized surface, and carbon powder with an average particle size of 50 μ or less are used,
A matrix powder having a carbon and oxygen content of the following formula is prepared.

However, [C]: Carbon content (weight%) of powder for base material [O]
:Oxygen content (wt%) of powder for base material Next, in the second step, this mixed powder is kneaded with an aqueous solution of binder 1, such as CMC, polyacrylic acid, water glass, etc., to make the mixed material thermally decomposable. It is applied to the skeleton of a porous network material, such as urethane foam. The coating can be performed, for example, by a spray method, a roll skies method, or the like.

Next, in the third step, the product of the second step is heated in a heat treatment furnace, for example, using a heat treatment furnace in an inert gas atmosphere.
When heated at 50° C. for 10 minutes, the urethane foam skeleton is thermally decomposed and removed. Further heating to 800° C. to 1200° C. and self-reductive sintering yields the porous iron catalyst carrier of the present invention. As already mentioned, in the present invention, a base material powder containing carbon and oxygen is used, and carbon is reduced by self-reducing sintering.
O gas is generated, and many micro-pores are formed in the steel frame due to the generation of CO gas.

When the base material powder is [C] > 2.1, it is 4/3 ([C] -2)
> [01 has a small number of micropores and is not preferred as a catalyst carrier, and [01>4/3 ([cl+
In case 7), the carrier strength of the molded product is weak.

In the present invention, self-reducing sintering is performed at 800 to 1200°C.

At temperatures below 800°C, self-reduction of iron oxide does not occur sufficiently.

Moreover, as a metal porous body, the strength is low and it cannot be put to practical use.

Moreover, at temperatures above 1200° C., oversintering occurs, the surface roughness of the bone portion disappears, and the micropores shrink, reducing the performance as a catalyst carrier.

FIG. 2 is a diagram showing the relationship between [C] and [0] of the base material powder and the volume ratio of micropores in the steel frame.

A in the figure is an example of claim (3), and [C
] and [0] to adjust the volume ratio of micropores.

Although expensive raw materials such as atomized iron powder or electrolytic iron powder may be used for the iron powder used to produce the catalyst carrier of the present invention, iron powder with a carbon content of 2.1% or more has excellent crushability. Therefore, it is preferable because it can be manufactured at low cost. Also, [C] is 2.1
% or more becomes iron powder whose surface is easily oxidized by wet grinding.

All of the powders for base material of the present invention have an average particle size of 50 μm or less. Unlike the general sintering method for powder alloys, the present invention does not use a high-pressure press or the like, but instead applies the mixed material to the skeleton of the pyrolyzable network porous body and sinters it. If the average particle size is 50μ or more, the contaminant will not form a slurry and will be difficult to apply.
Moreover, the bonding force between the sintered particles becomes insufficient.

Next, a method for producing a catalyst carrier according to the present invention according to claim (4) will be explained. In this method, the base material powder is formed from one or more selected from iron powder, iron oxide powder, and iron powder with an oxidized surface, pyrolyzer powder, and carbon powder if necessary. ing. Incidentally, the average particle size of each of the above-mentioned powders is 50 μm or less, as in the case of claim (3). The method according to claim (4), wherein the pyrolysis agent powder in this method refers to organic powder such as plastic powder, organic polymer material powder, and sawdust, or carbonate powder such as limestone powder. Using the base material powder, the second and third steps described in claim (3) are performed to produce a catalyst carrier. The pyrolysis agent powder can be decomposed in the third step and disappeared at the same time or through post-treatment, but the traces of decomposition and disappearance become micropores, further increasing the number of micropores in the steel frame. That will happen.

However, according to the findings of the present inventors, if the mixing ratio of the pyrolyzer powder exceeds 50%, it is difficult to maintain the kneaded material in a good slurry state in the second step, and the coating on the urethane foam skeleton becomes difficult. Sexuality becomes poor.

Therefore, it is preferable that the amount of pyrolysis agent powder mixed is 50% or less.
An example was shown in which a matrix powder containing 50% of plastic powder was used; however, by using a pyrolytic agent powder, the number of micropores contained in the bones can be significantly increased.

[Example 1] The base material powder shown in Table 1 was kneaded with an aqueous CMC solution.

It was coated on a urethane foam skeleton with a pore diameter of 2 mm to a thickness of III1 by a spray method, and then subjected to the heat treatment shown in Table 2.
A porous iron plate-shaped catalyst carrier measuring 0.00 mm x 100 mm x 10 mm was manufactured.

Table 1 The state of the pores in the obtained porous catalyst carrier is also shown in Table 2. In all of these catalyst carriers, the ribs formed macropores in a porous body, and the iron ribs were a sintered body with a rough surface and had many micropores.

Table 2 $: Volume ratio of micropores in the bone [Example 2] The catalyst carrier No. 2 in Table 2 was immersed in a platinum chloride solution, and then a current of 50 A was applied for 30 minutes to directly heat it to 600°C. A catalyst body was produced by heating with electricity. Four sheets of this catalyst body were used as an oxidation catalyst in a reaction vessel shown in FIG.

A mixed gas at room temperature was used as the processing gas, but when the catalyst carrier was directly heated to 300°C, the gas after processing was approximately 20°C.
At 0°C, the oxidation efficiency was 98%, indicating excellent catalytic performance.

[Example 3] After chromium-containing iron was treated with granular iron, surface oxidized iron powder (C: 3.5%, Si: 0.5%, Si: 0.5%) was wet-milled to have an average particle size of 5 μm.
01%, Mn: 0.8%, Cr: 10%, P: 0.01
%, s: o, oos%, oxygen: 8 phantoms were obtained. This surface-oxidized iron powder is mixed with 50% volume ratio of plastic powder (average particle size lOμ), kneaded with CMC and water, applied to urethane foam by dip coating, and then heat treated (drying: 100°C x
lhr, degreasing: 350°C x 20 minutes.

Self-reduction = 800℃ x 30 minutes, sintering: 1100℃ x 30 minutes
(min., nitrogen atmosphere) to produce a catalyst carrier. In this catalyst carrier, the volume ratio of micropores in the bone portion was 55%.

This catalyst carrier is coated with a catalyst agent of a kneading solution of MnO□ and CuO powder
Alumisol) was applied, but the surface of the catalyst carrier bones is rough and there are many microbubbles, so it is easy to apply the coating.
After coating, the coating was baked at 800°C, but the catalyst layer did not peel off even when a thick coating of the catalyst agent was applied.

[Effects of the Invention] In the catalyst carrier of the present invention, the three-dimensional network-like bone portions form macropores, so when a catalyst agent is applied to the bone portions, the contact area between the passing fluid and the catalyst is increased. Becomes a strong catalyst.

Since the bone portion of the catalyst support of the present invention is a sintered body with a rough surface having micro-pores, there is no need to form a roughening layer on the bone portion, and even if the catalyst agent is applied as is, a sufficient thickness can be obtained. The catalyst agent can be easily applied.

Since the catalyst carrier of the present invention is electrically conductive, it is possible to apply a catalyst agent using electrical conductivity, such as electroplating. Furthermore, by directly applying electricity or inductively heating the catalyst carrier of the present invention, the catalyst can be heated to the maximum temperature for catalytic reaction in a simple manner.

Since the present invention uses iron powder, iron oxide powder, surface oxidized iron powder, etc., which are easy to crush and are inexpensive, as the main powder, the raw material cost is low, and therefore, it can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an enlarged example of the bone portion of the catalyst carrier of the present invention. FIG. 2 is a diagram showing an example of the relationship between base material powder and the generation of micropores in bone parts. Figure 3 shows an example of the use of a catalyst using the catalyst carrier of the present invention.
This is a diagram. 1: macro pores, 2: iron skeleton, 3: micro pores,
4: Catalyst, 5: Processing gas, 6: Catalyst reaction vessel,
7: Power source for heating the catalyst carrier. Figure 1 Patent applicant Nippon Steel Corporation

Claims (6)

[Claims] (1) A porous iron catalyst carrier characterized in that the iron skeleton forms macro-pores of a porous body, and the iron skeleton is made of a sintered body having micro-pores. (2) The porous iron catalyst carrier according to claim (1), wherein the iron skeleton is an iron skeleton containing an alloying element. (3) Mixing one or more selected from iron powder, iron oxide powder, and surface-oxidized iron powder with an average particle size of 50 μ or less, or further carbon powder with an average particle size of 50 μ or less, A first step of mixing to produce a base material powder with a carbon and oxygen content of the following formula 1, and kneading the base material powder with a binder and applying it to the skeleton of the pyrolyzable network porous body. a second step, and a third step of heating the product of the second step to remove the pyrolyzable network porous material and further sintering the coated material by self-reduction. Method for manufacturing a porous iron catalyst carrier, which is made of a sintered body that forms pores and the iron skeleton has micropores [C]>2.1...1 4/3 ([C]-2 )<[O]<4/3([C]+7)
...1 However, [C]: Carbon content (weight%) of base material powder [O]: Oxygen content (weight%) of base material powder (4) one or more selected from iron powder, iron oxide powder, and surface-oxidized iron powder with an average particle size of 50μ or less; and pyrolyzer powder with an average particle size of 50μ or less, or A first step of producing a base material powder by further mixing carbon powder with an average particle size of 50μ or less, and kneading the base material powder with a binder and applying it to the skeleton of the pyrolyzable network porous body. and a third step of heating the product of the second step to remove the pyrolytic agent powder and the pyrolytic reticulated porous material, and further self-sintering the coated material. A method for producing a porous iron catalyst carrier comprising a sintered body that forms macro pores in a porous body and the iron skeleton has micro pores. (5) Claim (4) wherein the pyrolysis agent powder is a pyrolysis agent powder consisting of one or more selected from organic substance powder and carbonate powder.
), the method for producing a porous iron catalyst carrier (6) Production of a porous iron catalyst carrier according to claim (3), (4), or (5), wherein the self-reducing sintering is heating at 800°C to 1200°C. law