JPH0631165A - Thin film-like catalyst for steam reforming - Google Patents

Abstract

PURPOSE:To miniaturize a reactor packed with a catalyst decrease installation area and the volume device of by forming a layer containing a material selected from Ni, Ru, Rh, Pt, Pd and these oxides as a catalytically active component on the surface of a core made of metal or ceramics and forming the catalyst excellent in efficiency of heat transfer. CONSTITUTION:The layer containing the material selected from Ni, Ru, Rh, Pt, Pd and these oxides is formed on one part or all part of the surface of the core 0.01-3mm in thickness made of the metal or the ceramics to constitute the thin film type catalyst for steam reforming 0.015-3.5mm in thickness. Then, the catalyst is preferably applied to the fuel reformer for fuel cell suing hydrocarbons or alcohols as the fuel and a small-sized on-site fuel cell package is easily put into practice.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for a steam reforming reaction which can carry out a reaction to obtain a gas containing hydrogen by reacting a hydrocarbon or alcohol with steam. Alternatively, the present invention relates to a catalyst for a thin steam reforming reactor having a small installation area and a small reactor volume, which can be preferably applied as a fuel reforming device for a fuel cell using alcohol as a fuel.

[0002]

2. Description of the Related Art Conventional steam reforming catalysts capable of carrying out a reaction to obtain a hydrogen-containing gas by reacting hydrocarbons or alcohols with steam are of various types having a thickness of 5 to 20 mm. It is a tableting or extrusion catalyst.

[0003]

A reactor using such a conventional molded catalyst has a small amount of hydrogen generation,
The installation area and the device volume were large. Therefore, when assembling a small on-site fuel cell package, it has been a major obstacle to downsizing the entire package. As a means for overcoming this obstacle, in recent years, a steam reforming reaction device has been proposed in which the inside of a double cylinder having a relatively large diameter is used as a combustion chamber, and the outer peripheral portion is filled with a steam reforming chamber catalyst formed into pellets, These problems have been improved to some extent. However, this device has a problem that a large combustion chamber still remains in the center.

In order to improve this point, Japanese Unexamined Patent Publication (Kokai) No. 62-167203 proposes a reactor in which the combustion chamber has a rectangular shape and is alternately arranged with the steam reforming reaction chamber. However, even in this proposal, since the pellet-shaped catalyst is used in the steam reforming portion and the combustion portion, it cannot be said that the installation area and the apparatus volume are still sufficiently small. The above-mentioned improved double-cylindrical reactor having a relatively large diameter, reactors in which the combustion chamber is also rectangular and the steam reforming reaction chambers are alternately arranged (hereinafter collectively referred to as an improved reactor) In either case, the size of the compartments forming the combustion chamber and the steam reforming reaction chamber is practically 20 to 60 per width of one compartment.
It is necessary to have a size of about mm, and the installation area and the apparatus volume of the improved reactor as a whole are still considerably large. Therefore, further miniaturization has been demanded.

[0005]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to make a reactor extremely thinner than a conventional reactor in a steam reforming reaction in which hydrocarbons or alcohols are reacted with steam to produce hydrogen. Therefore, it is an object of the present invention to provide a completely new catalyst which can be made much smaller than the above-mentioned improved reactor in terms of installation area and apparatus volume.

[0006]

The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, if a specific core and a catalytically active component are combined and molded, a steam reforming catalyst is obtained. It has been found that it is possible to make the film into a thin film, and if this is used, the steam reforming chamber can be made into a thin plate, and the installation area of the steam reactor and the reactor volume can be made extremely small, and the present invention is completed. Came to.

That is, according to the present invention, a material selected from Ni, Ru, Rh, Pt, Pd and oxides thereof is partially or entirely formed on the surface of a core made of metal or ceramic and having a thickness of 0.01 to 3 mm. A thin film catalyst for steam reforming having a thickness of 0.015 to 3.5 mm, which is formed by forming a layer containing a catalytically active component.

The core constituting the catalyst of the present invention is not particularly limited as long as it does not adversely affect the steam reforming reaction and can fix a catalytically active component to a metal or a ceramic. Examples of the metal include steel, alumina, zirconia, tungsten, molybdenum, chromium and the like. Of these, as the steel, austenitic stainless steel AISI316, 3
04, 321, 347, 309, 310, 314, Inconel, HK-40 or ferritic stainless steel A
ISI410,430,431,446 etc. are mentioned. Examples of ceramics include silicon nitride, silicon carbide, boron nitride, sialon, and mullite.

The shape of these core substances is not particularly limited as long as the whole catalyst can be formed into a thin film, and may be foil, sheet, fiber, cloth or the like. In the case of fibrous, alumina fiber, zirconia fiber, tungsten fiber, molybdenum fiber, copper wire, alumina whiskers, iron whiskers, chromium whiskers, boron nitride fibers, silicon carbide fibers, silicon carbide whiskers, silicon nitride whiskers, etc. are used. it can.

The thickness of the core is 0.01 to 3 mm, but
1 to 0.5 mm is more preferable. If it is less than 0.01 mm, the strength may be insufficient, and if it exceeds 3 mm, it becomes difficult to mold a sufficiently thin catalyst.

The layers formed on a part or all of the surfaces of these cores contain Ni, Ru, Rh and P as catalytically active components.
It contains a substance selected from t, Pd and oxides thereof. More specifically, Ni, NiO, Ru, Rh, P
and t and Pd. The catalyst layer may further contain a carrier component and a catalytically active auxiliary component used in a conventional steam reforming catalyst. Examples of these components include ZrO ₂ , Al ₂ O ₃ , Cr ₂ O ₃ , CoO,
WO ₃ , MoO ₃ , SiO ₂ , La ₂ O ₃ , BaO, Ca
_{O, K 2 O, CeO,} Fe 2 O 3 and the like. In addition,
In addition to these components, the catalyst layer may further contain a component for reinforcing strength and other components.

The blending amount of each component in these catalyst layers differs depending on the components used and the like, but Ni, Ru, Rh,
0.1 to 30% by weight of Pt, Pd or their oxides,
It is preferable that the catalytically active auxiliary component is 0.1 to 10% by weight (hereinafter, simply expressed as%), and the carrier component is approximately 60 to 98%.

In order to form a layer of the catalyst component consisting of the catalyst main active component, the catalyst active auxiliary component and the carrier component on the surface of the core, for example, the following four kinds of methods may be adopted. (1) Vacuum evaporation method: In a high vacuum, the catalyst component is heated to a high temperature to evaporate, and the vapor collides with the core, where it is cooled and solidified.

(2) Sputtering method: When the surface of a solid catalyst component is irradiated with an ion beam having a kinetic energy of several tens of eV or more, the atoms existing in the vicinity of the surface of the component have the kinetic energy of the ion beam. Are taken out into a vacuum and the atoms reach the core surface to form a film.
An inert material such as Ar or Kr is used as the ion beam, and direct current bipolar sputtering, direct current bias sputtering, asymmetrical alternating current sputtering, getter sputtering, high frequency sputtering or the like is used as a sputtering method for generating the ion beam. It

(3) Chemical method: A desired catalyst component layer is formed by supplying a compound consisting of a catalyst component or a gas of a simple substance onto the core and performing a chemical reaction in the gas phase or on the surface of the core.

(4) Immersion coating method: First, the core is dipped in a solution of a carrier component of the above catalyst components to coat the carrier component solution, and this coating film is baked at a high temperature for a short time. This dip coating and baking operation is repeated to form a carrier component film having a desired thickness, and this film is baked at a temperature higher than the above and for a long time. Next, the active ingredient and the third ingredient of the above-mentioned catalyst ingredients are carried on the carrier ingredient film by the same dip coating method as in the case of the carrier ingredient, and baked at a high temperature for a long time. When a metal is used for the core, the pretreatment to make a grain on the metal surface layer helps improve the adhesion of the coated surface,
Alternatively, it is alloyed with Zr and is oxidized to produce Al ₂ O ₃ , Z.
It is preferable to prepare a surface layer of rO ₂ and perform pretreatment such as improving adhesion with the carrier coating layer.

The layer of catalyst components formed is 0.005-
It is preferably about 2 mm, particularly 0.01 to 1 mm. If it is too thick, it becomes meaningless to make it into a thin film. On the contrary, if it is too thin, the catalytic effect cannot be sufficiently exerted.

The thickness of the thus obtained thin film catalyst for steam reforming of the present invention is determined by the thickness of the core and the catalyst component layer, but is in the range of 0.015 to 3.5 mm, preferably The range is 0.1 to 2 mm. If it is less than 0.015 mm, there are drawbacks such as insufficient catalytic effect and insufficient strength, and if it exceeds 3.5 mm, it becomes meaningless to form a thin film.
The shape of the catalyst of the present invention is a thin film, and the thin film here means that the thickness is thin, its length,
The width is not limited. The shape is determined by the shape of the core.

By using the catalyst of the present invention, the steam reforming reactor can be made thin. The thin steam reforming reactor is configured, for example, as a plurality of plate-shaped compartments, which are stacked one upon the other as shown in FIG. 1, as a heating chamber and a reaction chamber including a steam reforming thin film catalyst. This will be achieved. To hold the thin film catalyst of the present invention in the reaction chamber of such a thin steam reforming reactor, for example, as shown in FIG.
A thin spacer (for example, wire mesh) that can secure a fluid flow between the plate-shaped reaction chamber side wall 9 and the thin-film catalyst 1 as shown in FIG.
8 is used to bend it into a corrugated shape as shown in the figure, and the thin film catalyst 1 is sandwiched between the two folded spacers 8 and placed in the reaction chamber.

As the raw material capable of steam reforming using the thin film catalyst of the present invention, known hydrocarbons, alcohols,
For example, C _{1 to} C ₄ hydrocarbons, naphtha kerosene hydrocarbons,
Examples thereof include C _{1 to} C ₄ alcohols and C ₅ or more alcohols. The reaction conditions for steam reforming these raw materials using the thin film catalyst of the present invention are generally about 200 ° C.
~ 900 ° C, pressure 30 kg / cm ² or less (absolute pressure), preferably about 0.5-15 kg / cm ² , LHSV about 0.5-6 h
^-1 , S (steam) / C (carbon) (molar ratio) is preferably about 2-5.

[0021]

The function of the steam reforming reaction is very high, but the steam reforming reaction is a very large endothermic reaction, so that the substantial reaction rate is limited by the heat transfer rate. There is. So far, as a measure to improve the heat transfer area,
Attempts were also made to improve the plate type reaction tube,
That was not enough.

That is, a plate-type reaction tube was filled with a conventional pellet-shaped molded catalyst to form a reaction chamber, and the thickness of this reaction chamber was reduced to increase the heat transfer area per unit catalyst. However, due to the pressure loss of the reaction bed, the pellet size is limited to about 3 mm, and thus the thickness of the reaction chamber is limited to about 10 mm. Moreover, since the flow of the gas in the reaction chamber passes through the gap between the pellet catalysts, the flow in the boundary film portion of the wall of the reaction chamber becomes poor, which is an obstacle to heat transfer.

On the other hand, when the thin film catalyst of the present invention is used, the thickness of the reaction chamber (distance between plates) can be made extremely small as compared with the case where the conventional pellet catalyst is used. The problem of heat area can be solved. That is, since the catalyst is in the form of a thin film, pressure loss does not occur and the plate interval can be narrowed,
The flow of the gas body in the film part of the plate part becomes good, and heat transfer resistance does not occur in that part. Moreover, the thin film catalyst of the present invention widens the heat transfer area of the catalyst itself.

As a result, in the reactor using the thin film catalyst of the present invention, the heat transfer rate is improved, and the reaction can be performed at a higher speed than in the case of using the conventional pellet catalyst.
As a result of this, the footprint and reactor volume are significantly reduced over when using conventional pelletized catalysts.

[0025]

The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1 Austenitic stainless steel AISI 316 (40 mm × 4) surface-treated so that alumina was easily formed.
A 0 mm x 0.1 mm core metal foil is dipped and applied in a solution (sol) of aluminum hydroxide and baked at 600 ° C for 2 minutes.
This dip coating / baking operation is repeated to obtain a desired thickness of 0.
Get 5mm. This is baked at 1000 ° C. for 30 minutes. Then, using an aqueous solution of potassium nitrate and an aqueous solution of nickel nitrate, immersed in each of them, and baked at 900 ° C. for 2 hours, a catalyst A having a thickness of 0.65 mm in which K ₂ O 5% and NiO 15% were supported on alumina on the core. Was prepared.

Example 2 In the same manner as in Example 1, Pd 1.5% and NiO 1 were added to alumina on the core by immersing in an aqueous solution of palladium chloride instead of potassium nitrate in Example 1, drying and reducing.
A catalyst B having a thickness of 0.63 mm and supporting 5% was prepared.

Example 3 Example 1 was repeated except that chloroplatinic acid and ruthenium (III) chloride were used instead of palladium chloride in Example 2.
Pt (1.5%) / Ni on alumina on the core in the same way as
O (15%) supported catalyst of 0.6 mm thickness and Ru
(1.5%) / NiO (15%) supported thickness 0.
A 6 mm catalyst D was prepared.

Example 4 The catalyst shown in Table 1 was prepared in the same manner as in Example 1, except that the material of the metal foil which was the core of the catalyst was changed. The catalyst components are the same as in Example 1.

[0030]

[Table 1]

Example 5 Using a ceramic sheet or fiber instead of the metal foil as the core of the catalyst, the solution is applied by dipping in a solution (sol) of aluminum hydroxide and baked at 600 ° C. for 2 minutes. This dip coating / baking operation is repeated to obtain a desired thickness. 1000 ° C
Bake for 30 minutes. Then, using an aqueous solution of nickel nitrate, it was immersed in each and baked at 900 ° C. for 2 hours, and then La ₂ O ₃ , BaO, ZrO ₂ and Fe ₂ O were used as co-catalysts.
Catalysts of Table 2 bearing ₃ were prepared.

[0032]

[Table 2]

Example 6 Austenitic stainless steel was prepared in the same manner as in Example 1.
Aluminum hydroxide was applied onto the AISI 316 foil by dipping, baking and firing to form an alumina layer on stainless steel (thickness 0.5 mm). Then, it is immersed in an aqueous solution of zirconyl nitrate and baked at 900 ° C. for 3 hours to obtain ruthenium (III) chloride.
It was immersed in an aqueous solution of, dried, and reduced. A catalyst I having a thickness of 0.62 mm, in which 5% ZrO ₂ and 2% Ru were supported on alumina on the core, was prepared.

Example 7 Ru 2% and BaO 5% were supported on alumina on the core by the same method as in Example 6 except that an aqueous solution of barium nitrate was used instead of zirconyl nitrate and calcined at 550 ° C. for 3 hours. A catalyst J having a thickness of 0.65 mm was prepared.

Example 8 The procedure of Example 6 was repeated except that chromium (III) nitrate was used in place of zirconyl nitrate and palladium chloride and chloroplatinic acid were used in place of ruthenium (III) chloride. Pd (1.5%) / Cr ₂ O on alumina
0.6 (thickness 0.6 mm) catalysts K and P loaded with ₃ (1.5%)
A catalyst L having a thickness of 0.6 mm and supporting t (1.5%) / Cr ₂ O ₃ (1.5%) was prepared.

Example 9 The catalyst shown in Table 3 was prepared in the same manner as in Example 6 except that the material of the metal foil used as the core of the catalyst was changed. The catalyst components are the same as in Example 1.

[0037]

[Table 3]

Example 10 A ceramic sheet or fiber was used in place of the metal foil which was the core of the catalyst, and was dipped and applied in a zirconium hydroxide solution,
Bake at 600 ° C for 2 minutes. This dip coating / baking operation is repeated to obtain a desired thickness (zirconia amount 0.8 g). This is baked at 900 ° C. for 30 minutes. Then, it is immersed in a rhodium chloride aqueous solution, dried, and reduced. Then, as co-catalyst, CaO, BaO, NiO, CeO, La ₂ O ₃
The supported catalysts of Table 4 were prepared.

[0039]

[Table 4]

Test Example 1 The catalyst prepared according to Examples 1, 4, 6 and 6 was placed in the center of the reaction chamber 6 (inside dimensions 40 mm × 40 mm × 4 mm) in FIG.
As shown in FIG. 2, a thin spacer (wire mesh) 8 that can secure a fluid flow is used between the side wall of the plate-shaped reaction chamber and the thin film catalyst 1, and the thin film catalyst 1 is sandwiched between two spacers and placed in the reaction chamber. Then, heating chambers were provided on both sides of the reaction chamber. Using the reforming reactor configured as described above, using kerosene (sulfur content 0.18 ppm) and steam sufficiently discharged as reforming raw material from the line 2 to keep the reaction chamber outlet temperature at 800 ° C. Then, a high temperature gas (gas obtained by another combustion facility) was introduced into the heating chamber 7 through the line 3 to carry out the reforming reaction. The results are shown in Table 5.
Shown in. For comparison, a conventional pellet catalyst (using the same amount of Al ₂ O ₃ as the catalyst A as a carrier, NiO 15%
And a catalyst b having K ₂ O 5% as an active metal or a pellet-shaped catalyst b (the same amount of Al ₂ O ₃ as the catalyst I as a carrier,
Using a cylindrical reactor filled with 2% and ZrO ₂ 5% as an active metal), kerosene (sulfur content 0.18 ppm) and water vapor that had been sufficiently drained were used, and the reaction chamber outlet temperature was adjusted to 8
Table 6 shows the results of the reforming reaction while maintaining the temperature at 00 ° C.

[0041]

[Table 5]

[0042]

[Table 6]

Test Example 2 The catalysts prepared according to Examples 2, 3, 7 and 8 were placed in the same reactor as in Test Example 1. Using the reforming reactor configured as described above, methanol and steam are used as the reforming raw materials from the line 2, and a high temperature gas (other combustion equipment) is used in the heating chamber 7 so as to maintain the reaction chamber outlet temperature at 400 ° C. The gas obtained in step 1) was introduced through line 3 to carry out the reforming reaction. The results are shown in Table 7. For comparison, the conventional pellet-shaped catalyst c (using the same amount of Al ₂ O ₃ as the catalyst B as the carrier and NiO
15% and Pd 1% as an active metal) or pelletized catalyst d (the same amount of Al ₂ O ₃ as catalyst J is used as a carrier,
Ru 2% and BaO 5% as active metals)
Table 8 shows the results of carrying out the reforming reaction by using a cylindrical reactor filled with methanol with methanol and steam as the reforming raw materials while keeping the outlet temperature of the reaction chamber at 400 ° C.

[0044]

[Table 7]

[0045]

[Table 8]

Test Example 3 Methane, butane and naphtha were used as reforming raw materials,
Using the catalyst prepared by the method of Example 1 or Example 6,
A reforming reaction was carried out using the reactor of FIG. The results are shown in Table 9 and Table 10.

[0047]

[Table 9]

[0048]

[Table 10]

When the catalysts prepared in Examples 5 and 10 were reacted in the same manner as in Test Example 1, results similar to those of Catalyst A and Catalyst I in Table 5 were obtained.

As is clear from Tables 5 to 10, the reactor packed with the thin film catalyst for steam reforming of the present invention has a reaction material feed rate higher than that of the reactor packed with the conventional pellet steam reforming catalyst. Is similar to that of the conventional reactor using the pellet-shaped steam reforming catalyst, and has the same function as that of the reactor packed with the thin-film steam reforming catalyst of the present invention. When the reaction material feed rate was increased, the reaction rate decreased. From this, it was proved that the reactor filled with the thin film catalyst for steam reforming of the present invention had a high heat transfer rate and a high reaction rate.

[0051]

EFFECTS OF THE INVENTION The thin film catalyst for steam reforming of the present invention has excellent heat transfer efficiency, and the reactor filled with this catalyst can be significantly downsized, and the installation area and the apparatus volume can be made extremely small. . Therefore, it can be preferably applied as a fuel reformer for a fuel cell using hydrocarbons or alcohols as a fuel, and a small on-site fuel cell package can be easily put into practical use.

[Brief description of drawings]

FIG. 1 is an external view for explaining an example of a reactor filled with a thin film catalyst of the present invention.

FIG. 2 is a cross-sectional view of FIG.

[Explanation of symbols] 1 thin film catalyst for steam reforming 2 reforming raw material introduction line 3 high temperature gas introduction line 4 gas outlet line after reforming reaction 5 exhaust heat gas outlet line 6 reaction chamber 7 heating chamber 8 spacer 9 reaction Side wall

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B01J 23/78 M 8017-4G 23/89 M 8017-4G 35/06 G 7821-4G C01B 3 / 40

Claims (1)

[Claims] 1. Thickness 0.0 made of metal or ceramic
Ni, Ru, R on part or all of the surface of the core of 1-3 mm
A steam reforming thin film catalyst having a thickness of 0.015 to 3.5 mm, which is formed by forming a layer containing a substance selected from h, Pt, Pd and oxides thereof as a catalytically active component.