JPS61287452A - Production of lamellar catalyst - Google Patents

Abstract

PURPOSE:To obtain a lamellar catalyst having a uniform thickness distribution by extruding coaxially a slurry contg. a catalyst and a carrier or the like on a supporter such as a pipe and a rod, drying it to make a ring-shaped green body and opening it to make a lamellar shape. CONSTITUTION:In relation to a lamellar catalyst used for a reforming type fuel cell or the like, both a slurry 11 contg. a catalyst, a carrier and an aid catalyst, if necessary, and a supporter 12 such as a pipe and a rod are inserted into a vessel or an extruder provided with a mouthpiece having a prescribed shape and this supporter 12 is coaxially extruded from the mouthpiece having the prescribed shape together with the slurry 11 while sticking the slurry 11 on the supporter 12. A ring-shaped green body is obtained by heating the ring- shaped slurry on the supporter 12 and a lamellar green body is obtained by opening it in the extrusion direction on the supporter 12 and developing it. In such a way, the lamellar catalyst having a regular thickness distribution in accordance with the mouthpiece shape is obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for producing a plate-shaped catalyst, which has uniform plate-like properties that can be suitably used as a reforming catalyst in, for example, a reforming fuel cell. The present invention relates to a method for producing a plate-shaped catalyst.

(Prior art) In recent years, molten carbonate fuel cells, which use molten carbonate as an electrolyte and operate at high temperatures, have high power generation efficiency and can be used with many types of fuel, such as platinum. It is attracting attention because it does not require a precious metal catalyst, and high-quality waste heat is recovered for high-temperature operation, and its practical application is progressing.

Conventionally, in such molten carbonate fuel cells, a single cell is constructed by stacking a positive electrode plate and a negative electrode plate with an electrolyte plate containing molten carbonate in between, and this single cell is made up of a current collector plate and a separator. A fuel cell is constructed by stacking a large number of them with each other in between. The separator and/or the electrode plate may be provided with grooves as passages for fuel gas or oxidizing gas, the fuel gas being e.g. hydrogen and/or carbon oxide, and the oxidizing agent being e.g. air. and carbon dioxide gas are supplied, and predetermined electrochemical reactions are performed at the electrodes, respectively.

However, when using something other than hydrogen and/or -carbon oxide as a fuel, such as LNG such as methane or methanol, these fuels must be converted into hydrogen and/or -carbon oxide by reforming in advance. Ru. Two types of reforming methods are known: an external reforming method and an internal reforming method.

The external reforming method is a method in which a reformer is disposed outside the battery, and fuel is reformed in advance and then supplied to the fuel gas passage of the battery. On the other hand, the internal reforming method is a method in which fuel is reformed within the battery by utilizing the high operating temperature of the battery, and a reforming catalyst is usually supported on the negative electrode or separator.

In this way, whether the reforming catalyst is supported on the negative electrode plate and used in an internal reforming fuel cell, or it is used by filling the reformer reactor in an external reforming fuel cell, when the catalyst is plate-shaped, In order to prevent distortion and cracking due to heat during use, plate catalysts are required to have a uniform plate shape, and the larger the area or the thinner the plate catalyst is, the more uniform the plate shape will be. Demands become higher.

For example, when supporting a reforming catalyst on the negative electrode plate, if the plate-shaped catalyst undergoes uneven shape changes due to thermal causes, such as expansion and contraction, and distortion during long-term continuous operation, the adjacent Contact resistance between battery components increases and battery performance deteriorates. In addition, even when using a plate-shaped catalyst in an external re-former, if the plate-shaped catalyst is strained and deformed during fuel cell operation, the reaction will occur unevenly in the re-former, and local overheating will cause the plate-shaped catalyst to deform. or rehoming activity is impaired.

However, in the production of plate-shaped catalysts, when a slurry containing a catalyst component is molded into a flat plate from the beginning as in the past, it is not easy to produce a plate-shaped molded product having uniform flatness. For example, when using the extrusion method, conventionally,
Although the extrusion speed of the slurry and the feed rate of the extruded plate-shaped product are strictly controlled, the larger the area of the plate-shaped product or the thinner the plate-shaped product, the more likely the slurry extruded during extrusion will wave. Therefore, it is difficult to obtain a plate-like article having a uniform thickness or a regular thickness distribution and a predetermined cross-sectional shape. Moreover, in the step of heating and drying such an extrudate, further bending and deformation are unavoidable. Furthermore, as described above, it is necessary to strictly control the extrusion speed of the slurry and the feeding speed of the extruded plate-like material, making the equipment complex and expensive.

(Object of the Invention) Therefore, the present invention has been made in order to solve the various problems described in 1. in the production of plate-shaped catalysts, and is aimed at producing a plate-like catalyst having a uniform thickness distribution or a regular catalyst. The purpose is to provide a plate-shaped catalyst as a plate-shaped molded product having a predetermined cross-sectional shape with a thickness distribution, and in particular,
For example, an object of the present invention is to provide a method for manufacturing a plate-shaped catalyst that can be suitably used as a reforming catalyst for a reforming type molten carbonate fuel cell.

(Structure of the Invention) The first method for producing a plate-shaped catalyst according to the present invention is to prepare a support made of a tube or a rod containing a catalyst, a carrier, and optionally a co-catalyst, or a precursor thereof. The slurry is coaxially extruded from a mouth mold having a predetermined shape to obtain a support to which the slurry is adhered in a predetermined cross-sectional shape, and this slurry is dried on the support. The method is characterized in that a green body is obtained, and then this annular green body is cut into a flat plate shape by cutting the support in the extrusion direction, and then heated and fired.

The second method for producing a plate-shaped catalyst according to the present invention is +al
A support consisting of a tube or a rod is coaxially extruded from a mouth mold having a predetermined shape together with a slurry containing a support and, if necessary, a cocatalyst or a precursor thereof. Obtain a support attached in a cross-sectional shape,
This slurry is dried on this support to obtain an annular green body on the support, and this annular green body is cut in the extrusion direction with support 1 to form a flat plate, and then heated and baked. Then, fbl This plate-like carrier is coated with or impregnated with a solution or slurry containing a catalyst and, if necessary, a co-catalyst and a carrier or their precursors, and then heated and calcined again. It is characterized by supporting a catalyst.

In the present invention, the catalyst, carrier and/or co-catalyst contained in the slurry shall contain precursors that can be activated into the catalyst, carrier and co-catalyst, respectively, by predetermined heating and calcination in a reducing atmosphere or an oxidizing atmosphere. . Examples of such precursors include, for example, metal compounds such as oxides and various salts that are activated by reduction to active metal species or co-catalysts by heating and calcination in a reducing atmosphere, and metal compounds such as oxides and various salts, and Examples include various salts that can be oxidized to active oxide catalysts, carriers, and co-catalysts.

In the first method according to the invention, the catalyst components consisting of catalyst, carrier and optionally co-catalyst are mixed together with a solvent and optionally the required auxiliary agents such as binders, emollients, peptizers, etc. and slurry. As a solvent, usually
Water is preferably used and therefore also as a binder.
Generally, water-soluble resins such as polyvinyl alcohol and polyethylene glycol are preferably used.

When the plate-shaped catalyst according to the present invention is used as a reforming catalyst for a molten carbonate fuel cell as described above, the active metal species is usually one or more of nickel, iron, and nickel-iron alloy. .

These are conventionally known as reforming catalysts for molten carbonate fuel cells. Although the method for producing a plate-shaped catalyst according to the present invention is not limited to the above-mentioned examples in terms of catalytically active species, a plate-shaped catalyst for reforming for a molten carbonate fuel cell will be described below.

These active metal species are preferably cobalt, manganese, tungsten, molybdenum, or one or more of these used in combination as a cocatalyst in order to improve the durability and sulfur resistance of the catalyst.

Further, it is preferable that the catalyst made of such an active metal species is supported on a suitable carrier. Such carriers include
For example, alumina, titania, zirconia, etc. are preferably used, but the material is not limited to these.

In the present invention, as described above, the slurry appropriately contains auxiliary agents such as a binder, a plasticizer, and a deflocculant, if necessary. The plasticizer is added to give the slurry the required viscosity, and the deflocculant is added to obtain a uniform slurry. Although not particularly limited, examples of the plasticizer include, for example. , a polyol-based resin, etc., and as a deflocculant, for example, a polymer polycarboxylic acid ammonium salt or the like is used.

The method for preparing slurry of inorganic compounds and fine metal powder is as follows:
These conventional techniques are already widely known in various technical fields, and in the present invention, a slurry having an appropriate viscosity can be obtained according to these conventional techniques. Therefore, the amount of catalyst components such as catalyst, carrier and co-catalyst, and the amount of binder, plasticizer, peptizer, etc. in the slurry are not necessarily limited, but for example, in the slurry,
Catalyst component powder 40-80% by weight, solvent 10-50% by weight
, 3 to 30% by weight of binder, 0 to 10% by weight of plasticizer and 0 to 5% by weight of peptizer are suitable.

In addition, the slurry viscosity is 2000 to 200 at 25°C.
Approximately 0.00 cps is suitable.

In the first method according to the present invention, a slurry containing the catalyst component as described above is coaxially extruded together with a support through a spout having a predetermined shape, and the slurry is attached to the support with a predetermined cross-sectional shape. Get a body.

In the present invention, the support is preferably a heat-resistant round rod or a tube with both ends sealed, and for example, a round rod or tube made of stainless steel is preferable.

In the present invention, the slurry and support are charged into a container or extruder equipped with a mouth mold having a predetermined shape, and while the slurry is attached to the support, the support is formed into a predetermined shape together with the slurry. The slurry is coaxially extruded from a mold having a mouth to obtain a support having a predetermined cross-sectional shape on the peripheral surface of the slurry.

That is, when the mouth shape is a uniform circular hole, it is possible to obtain a support to which the slurry is attached in an annular shape having a clearly uniform thickness distribution. In addition, if the mouth shape is, for example, a circular hole whose periphery is formed by a regular uneven shape, it has a regular thickness distribution due to the regular uneven cross-sectional shape, as shown in FIG. A support 12 to which slurry 11 is attached in an annular manner can be obtained.

Then, according to the present invention, the annular slurry on the support is heated and the solvent is removed to obtain an annular green body on the support. Since this green body still contains a binder and is flexible, a flat green body can be obtained by cutting it in the extrusion direction on a support and rolling it out. This is heated and fired at a required temperature in a predetermined atmosphere depending on the catalyst component to activate each catalyst component and remove the binder to produce a plate-shaped catalyst with a uniform thickness distribution or as described above. When the mouth mold has a predetermined cross-sectional shape, for example, as shown in FIG. be able to.

Depending on the type, molding aids such as plasticizers and peptizers may remain in the molded product even after the above-mentioned firing, but they may also serve as sintering aids, so they must be removed by firing. Not necessarily.

The heating and firing temperature of the green body depends on the catalyst components, but for example, in the case of the above-mentioned nickel catalyst for reforming in the molten carbonate fuel cell, about 650° C. is suitable. However, this firing temperature should be appropriately selected depending on the firing atmosphere and the catalyst components used.

FIG. 2 shows an example of an extruder that can be suitably used to carry out the method of the present invention. That is, the extruder 21 is
The body wall 22 has a slurry supply port 23, and the tip thereof is provided with a mouth mold 24 having a predetermined cross-sectional shape. A nipple 26 having a lip 25 coaxially with the body and a sleeve 27 integral with the nipple 26 are rotatably (and forwardly) accommodated in the barrel, facing the date mold, and a sleeve 27 is supported within the sleeve and nipple. A body 28 is inserted and coaxially extruded through the nipple and the mouth mold into the mouth mold. The nipple has a gap 29 between it and the trunk wall at its tip, and also has an annular inclined groove 30 inclined with respect to the axial direction of the slurry supply port, and the gap is communicated with the inclined groove. There is.

Therefore, slurry is supplied from the slurry supply port to the inclined groove, and as the sleeve rotates (and moves forward), the slurry is pushed out through the gap and the mouth mold, and the support inside the sleeve is also pushed out coaxially with the mouth mold. By doing so, it is possible to obtain a support on which the slurry 31 is adhered in a cross-sectional shape corresponding to the cross-sectional shape of the mouth mold. The annular slurry on the support is heated and dried as described above to obtain an annular green body, which is cut in the extrusion direction on the support to form a flat plate, and then heated and baked to form a mouth-shaped green body. Depending on the cross-sectional shape, a plate-shaped catalyst having a uniform thickness distribution or a plate-shaped catalyst having a predetermined cross-sectional shape due to a regular thickness distribution can be obtained.

The second method according to the present invention is to extrude a slurry containing a carrier and, if necessary, a co-catalyst together with the support through a mouth die in the same manner as above, and heat and dry it to obtain an annular green body.
This is cut in the extrusion direction and developed into a flat plate shape, and then heated and fired to obtain a flat support. Next, this carrier is added to a solution containing a catalyst and, if necessary, a co-catalyst, usually an aqueous solution. A plate-shaped catalyst is obtained by coating or impregnating the catalyst and heating and baking it at a predetermined temperature in a predetermined atmosphere.

If the catalytically active metal species is, for example, nickel, the carrier is coated or impregnated with an aqueous solution containing nickel sulfate as a precursor. In this case, a slurry may be used instead of the above solution, and the solution or slurry may further contain a carrier or a co-catalyst as required.

(Effects of the Invention) As described below, according to the method of the present invention, plate-like catalysts having a uniform thickness distribution or a regular thickness distribution can be easily observed regardless of their area or thickness. , you can definitely get one. In particular, according to the conventional method, a plate-shaped catalyst is produced by forming a slurry containing catalyst components into a plate shape from the beginning, heating and drying this, and then heating and calcining it. However, according to the method of the present invention, it is possible to extrude the slurry together with the support. Moreover, since it is heated and dried on the support, no bending or deformation occurs at this stage. Furthermore, in the method of the present invention, the extruder used has a simple structure, so the manufacturing cost is low.

(Examples) The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples in any way. still,
In the following, parts indicate parts by weight.

Example Fine nickel powder (active metal species, average particle size 2.5 μm) 60 parts water
30 parts plasticizer 1 part peptizer
A mixture of 3 parts and 6 parts of polyvinyl alcohol and polyethylene glycol (binder) was thoroughly mixed and stirred to achieve a viscosity of 5 at 25°C.
000 cps slurry was prepared.

This slurry is extruded coaxially with a stainless steel support rod through a circular hole-shaped mouth mold whose periphery is formed with regular uneven shapes using an extruder as shown in Fig. 2, so that the slurry is A support rod was obtained which was attached to the support rod so as to have a regular uneven thickness distribution. The slurry on this support rod was heated together with the support rod in air at a temperature of 60° C. for 2 hours to remove water and obtain an annular green body.

Next, this annular green body was cut in the extrusion direction, expanded to form a plate shape, and then heated and baked at a temperature of 650°C for 1.5 hours in a 60% hydrogen-40% nitrogen stream to cut the length and width of the green body. A plate-shaped catalyst was obtained with a height of about 315 mm, a height of the convex part of 31 mm, a height of 11 times of the four parts, and a width of 2 times of each of the convex parts and the four parts.

For comparison, a plate-shaped catalyst having a cross-sectional shape similar to that described above was manufactured using a conventional extrusion method.

Next, in order to examine the thermal strength of the five plate-shaped catalysts produced by the method of the present invention and the conventional method, they were tested in air at 300° using a fluidized bed thermal fatigue tester. Ten thermal cycles were given between C and 650°C. Heating time from 350℃ to 600℃ 10 minutes, holding time at 600℃ 15 minutes, from 600℃ to 3
The time for cooling down to 50°C was 10 minutes.

After such a thermal fatigue test, whether or not cracks had occurred on the surface of the electrode plate was visually inspected. The results are shown in the table.

It is clear that the electrode plate produced by the method of the present invention has excellent thermal strength.

Next, in order to evaluate the catalytic activity of the plate-shaped catalyst for reforming obtained in this way, it was supported between two stainless steel copper plates, leaving a gap between the plate-shaped catalyst and the plate-shaped catalyst described above. The following fuel gas was supplied to the void, re-forming was performed, and the composition of the gas after the reaction was analyzed.

The supplied fuel gas is methane 2.1%, water vapor 21.5%,
It consisted of 3.9% hydrogen and residual nitrogen, and the reaction conditions were a space velocity of 3830 hr" and a reaction temperature of 650°C. The gas composition after the reaction was 1.16% methane and 0.72% carbon dioxide.
%, hydrogen 7.4%, water vapor 17.3%, -carbon oxide 0.
15%, residual nitrogen, therefore the methane conversion is 4.
Since it is 2.5%, it is understood that the product of the present invention has almost the same catalytic activity as a commercially available reforming catalyst, and has a sufficient practical reforming function.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the cross-sectional shape of the slurry deposited on a support, FIG. 2 is a cross-sectional view showing an example of a plate-shaped catalyst obtained according to the method of the present invention, and FIG. FIG. 1 is a sectional view showing an example of an extruder that can be suitably used to carry out the method of the invention. DESCRIPTION OF SYMBOLS 11... Slurry, 12... Support, 13... Plate catalyst, 21... Extruder, 23... Slurry supply port, 24... Mouth type, 25... Lip, 26 ...Nipple, 28...Support, 29...Gap, 30...
Slanted groove, 31...Slurry. Figure 1 Figure 2

Claims (2)

[Claims] (1) Coaxially extruding a support consisting of a tube or rod together with a slurry containing a catalyst, a carrier, and if necessary a co-catalyst or a precursor thereof from a mouth mold having a predetermined shape, Obtain a support to which the slurry has been adhered in a predetermined cross-sectional shape, dry this slurry on this support to obtain an annular green body on the support, and then apply this annular green body on the support. A method for producing a plate-shaped catalyst, which comprises cutting the catalyst into a plate shape by cutting in the extrusion direction, and then heating and baking the catalyst. (2) (a) Coaxially extrude a support consisting of a tube or rod together with a slurry containing a carrier and a co-catalyst if necessary, or a precursor thereof from a mouth mold having a predetermined shape, and Obtain a support to which the slurry is attached in a predetermined cross-sectional shape, dry this slurry on this support to obtain an annular green body on the support, and extrude this annular green body on the support in the extrusion direction. After cutting it into a flat plate shape, heating and calcining it to obtain a plate-shaped carrier, and (b) adding a catalyst to this plate-shaped carrier and, if necessary, a solution containing a co-catalyst and a carrier or their precursors. Or, a method for producing a plate-shaped catalyst, which comprises applying or impregnating a slurry and then heating and calcining it again to support the catalyst.