JPWO2016047504A1 - Steam reforming catalyst composition and steam reforming catalyst - Google Patents

Abstract

We propose a new steam reforming catalyst composition in which the catalytic performance does not deteriorate even in a reduction treatment or reforming reaction at a temperature of 500 ° C. or higher. A steam reforming catalyst composition containing a steam reforming catalyst active component having an action of promoting a steam reforming reaction and catalytically active particles containing vanadium is proposed. By adding vanadium, the catalytic performance of the steam reforming catalytically active component is not degraded, and sintering during the reduction treatment or reforming reaction at a temperature of 500 ° C. or higher is suppressed. Deterioration can be suppressed.

Description

  The present invention relates to a steam reforming catalyst composition and steam containing a steam reforming catalyst active component having a function capable of promoting a steam reforming reaction for reforming a hydrocarbon-containing fuel gas to obtain hydrogen The present invention relates to a reforming catalyst.

  A fuel cell is a cell that converts chemical energy into electrical energy by electrochemically reacting hydrogen and oxygen. As a hydrogen source, hydrogen obtained by reforming city gas, hydrocarbons, or the like is used. It's being used. City gas is a gaseous fuel mainly composed of natural gas, and typically contains 87 vol% or more of methane.

In the steam reforming reaction for reforming city gas to obtain hydrogen, steam is added to hydrocarbon (CnHm), which is the main component of city gas, and a fuel reforming catalyst is used as shown in the following equation (1). The reaction for producing hydrogen (H ₂ ) through a chemical reaction proceeds as the main reaction. In addition, since carbon monoxide (CO) obtained by the reaction of the formula (1) is bonded to a large amount of water vapor, a reaction for generating hydrogen further proceeds by the water gas shift reaction (see the formula (2)). .

_{(1) ··· C n H m} + nH 2 O → nCO + (m / 2 + n) H 2
(2) ... CO + H ₂ O → CO ₂ + H ₂

  As a reforming catalyst used in such a steam reforming reaction, a nickel-based catalyst using a transition metal element typified by nickel as a catalytic active component is conventionally known.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-74396) discloses Cu, Co, Fe, Ni, Mn, Zn, Sn, Cd, Pd, as metal particle dispersed oxides that can function as a steam reforming catalyst. “Reducible metal oxides” such as Ag, Ru, Rh, Mo, W, and In oxides that can be reduced to metals in a hydrogen atmosphere at room temperature to 1500 ° C., Al, Mg, Si, Zr, Ti, Hf And oxide particles comprising a solid solution phase with a “refractory metal oxide” that is not reduced to a metal in a hydrogen atmosphere at room temperature to 1500 ° C., such as an oxide of Ce, and a surface on the surface of the oxide particles A metal particle-dispersed oxide is disclosed in which metal particles are precipitated and internal metal particles are precipitated inside the oxide particles.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2005-144402) discloses a catalytic activity comprising fine particles of a metal selected from iron group metals such as nickel as a steam reforming catalyst capable of suppressing coking (carbon deposition). A steam reforming catalyst having a core-shell type structure in which a component is a core portion and the periphery of the core portion is coated with a shell portion made of a catalyst carrier component selected from silica, alumina, zirconia and titania is disclosed.

JP-A-2005-74396 JP-A-2005-144402

By the way, with respect to the conventionally proposed transition metal catalyst using a transition metal element represented by nickel as a steam reforming catalyst active component, it is necessary to further improve the steam reforming performance.
Moreover, in order to actually use this type of transition metal catalyst as a steam reforming catalyst, it is necessary to use it after it has been activated by reduction treatment. However, when this type of catalyst is reduced at a temperature of 500 ° C. or higher, the oxide undergoes phase transition to the metal phase and causes sintering (sintering), so the activity of the steam reforming catalyst active component is reduced. Thus, the steam reforming catalyst active component has a problem that it cannot exhibit the catalytic performance inherently possessed.

  Therefore, the present invention is superior in steam reforming performance compared to the conventionally proposed transition metal-based catalysts in which a transition metal element is used as a steam reforming catalyst active component, and furthermore, reduction treatment at a temperature of 500 ° C. or higher. In addition, the present invention proposes a new steam reforming catalyst composition in which the catalyst performance does not deteriorate in the reforming reaction.

  The present invention proposes a steam reforming catalyst composition containing catalytically active particles containing a steam reforming catalyst active component and vanadium.

  The steam reforming catalyst composition proposed by the present invention is superior in steam reforming performance to the transition metal catalyst conventionally proposed by containing vanadium and is reduced at a temperature of 500 ° C. or higher. It is also possible to suppress the deterioration of the catalyst performance by suppressing sintering during the treatment or reforming reaction.

It is the block diagram which showed the outline of the fuel reforming evaluation apparatus used in the gas reforming evaluation test of an Example. It is a FE-SEM / EDX image of the steam reforming catalyst composition (sample) obtained in Example 2-1, (a) is an enlarged photograph (SEM image) of catalytically active particles, and (b) in the particles. It is the enlarged photograph which showed the distribution state of oxygen (O), (c) It was the enlarged photograph which showed the distribution state of vanadium (V) in the particle | grains, (d) showed the distribution state of nickel in the particle | grains. It is an enlarged photo. Note that “Grey”, “K”, and “L” in the upper left of FIG. 2 relate to observation conditions and are not related to the present invention. These “K” and “L” are symbols of characteristic X-rays used for element detection, and indicate the orbits (energy levels) of excited electrons. It is an XRD pattern of the steam reforming catalyst composition (sample before gas evaluation test, referred to as “pre”) obtained in Example 1, Examples 2-1 to 2-3 and Comparative Example 1. It is an XRD pattern of the steam reforming catalyst composition (sample before gas evaluation test, referred to as “pre”) obtained in Examples 2-4 to 2-7. It is an XRD pattern of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Example 1, Examples 2-1 to 2-3 and Comparative Example 1. It is an XRD pattern of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Examples 2-4 to 2-7. 3 is a SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Comparative Example 1; 2 is an SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Example 1. It is a SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Example 2-1. It is a SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Example 2-2. It is a SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Example 2-3. It is a SEM image of the steam reforming catalyst composition obtained in Example 2-4 (sample after gas evaluation test, referred to as “aged”). It is a SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Example 2-5. It is a SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Example 2-6. It is a SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Example 2-7.

  Next, the present invention will be described based on an embodiment. However, the present invention is not limited to the embodiment described below.

<This catalyst composition>
A steam reforming catalyst composition (hereinafter referred to as “the present catalyst composition”) as an example of an embodiment of the present invention includes catalytic active particles (hereinafter referred to as “the present catalyst particles”) containing a steam reforming catalytic active component and vanadium. A steam reforming catalyst composition.

  As a form of this catalyst composition, arbitrary forms, such as a powder, a slurry, a pellet, a layered product, can be taken.

(This catalyst particle)
The catalyst particles are catalytically active particles containing a steam reforming catalytically active component and vanadium.
Vanadium reacts with the steam reforming catalytic active component to form a composite oxide. This composite oxide is gradually reduced by the reduction treatment for activating the catalyst and exhibits activity. The reduced active ingredient is eventually deactivated by the sintering due to heat, but the remaining complex oxide is newly reduced by hydrogen during the reforming reaction and exhibits activity. By repeating this cycle, the active component is supplied and as a result, the life of the catalyst can be extended.
At this time, by adding vanadium to the catalyst particles containing the steam reforming catalytic active component such as nickel, compared with the case where no vanadium is contained, the reduction in the specific surface area after reduction activation is suppressed and the steam reforming performance is improved. Further, it is possible to effectively suppress a reduction in performance due to reduction activation treatment at a temperature of 500 ° C. or higher or sintering in the reforming reaction.

  The catalyst particles may be agglomerated particles obtained by aggregating primary particles, or may be particles obtained by monodispersing the primary particles. As an example, granular or acicular primary particles aggregate to form aggregated particles, and as described later, particles having a structure in which silicon oxide or zirconium oxide is present on the surface of the primary particles can be mentioned. it can.

(Steam reforming catalyst active ingredient)
As the steam reforming catalyst active component, an element known to have an action of promoting the steam reforming reaction can be used. For example, at least one element of Fe, Ni, Co, Ru, Rh, Pt, Pd, and Ir can be given. Two or more of these may be used. Among them, it is preferable to contain an iron group element such as Fe, Ni, or Co, and among these, it is preferable to contain Ni or Ni and Ru or Rh. Thus, when Ni and Ru or Rh are contained, Ru or Rh is preferable in that the steam reforming reaction can be further promoted and the conditions for the reduction activation of the present catalyst composition can be moderated.

  The steam reforming catalytically active component may be present in the form of a metal (including an alloy), an oxide (including a complex oxide), a mixture thereof, or a solid solution thereof. Preferably present. That is, it is preferably present as an oxide before the reduction activation treatment, and after the reduction treatment, it is preferably present in a state in which a part of the oxide is reduced, for example, a state in which a metal and an oxide are mixed.

(vanadium)
In the present catalyst particle, vanadium is preferably present in the state of an oxide, a metal, a mixture thereof, or a solid solution thereof. That is, it exists as an oxide in a state before the reduction activation treatment, and after the reduction activation treatment, at least a part of vanadium is in a state in which the oxide is reduced, for example, a steam reforming catalyst active component such as Ni. It is preferable that the alloy is formed, dissolved, or exists in the form of a mixture thereof.

The vanadium is preferably present on the surface of the catalytically active particles in order to efficiently act on the steam reforming catalytically active component. In particular, it is preferable to be present more on the surface than inside the catalytically active particles.
Further, the vanadium is more preferably present in a dispersed state on the surface without being unevenly scattered on the surface of the catalytically active particles.
In order for vanadium to be present on the surface of the catalytically active particles, nickel hydroxide (Ni (OH) ₂ ) is added to an aqueous solution containing a water-soluble vanadium compound, for example, vanadium such as ammonium vanadate (NH ₄ VO ₃ ). ) Catalytically active particle powder such as particle powder may be put in, impregnated, and fired. However, it is not limited to such a method.

When this catalyst particle contains vanadium, sintering can be effectively suppressed. In order not to deteriorate the activity of nickel which is a steam reforming catalyst active component, vanadium is preferably contained at a ratio of 1 mol% or more with respect to 100 mol% of the steam reforming catalyst active component.
However, when the content of vanadium is too large, when using an aqueous solution containing vanadium as described above, not only the workability may be reduced, but also vanadium pentoxide is produced when the present catalyst particles are produced. It is not preferable that the vanadium content is too large because the catalyst may be melted at the time of firing the catalyst.
From this point of view, the vanadium content is preferably 1 mol% or more with respect to 100 mol% of the steam reforming catalyst active component, more preferably 200 mol% or less, of which 2 mol% or more or 100 mol% or less, Among them, it is particularly preferable to contain it in a proportion of 3 mol% or more or 45 mol% or less.

(Surface condition)
The catalyst particles may have silicon oxide, zirconium oxide or both on the particle surface.
The presence of an appropriate amount of silicon oxide and / or zirconium oxide (also referred to as “surface oxide”) on the surface of the present catalyst particles containing vanadium (also referred to as “core particles”) In order to exhibit the anchor effect that the surface oxide restricts the movement of the constituent substances, reduction activation treatment and reforming reaction at a temperature of 500 ° C. or higher without lowering the catalytic performance inherent in the catalyst particles Time sintering can be further suppressed. In particular, the performance of the steam reforming catalyst after being exposed to a reducing environment or a high temperature environment of 550 ° C. or higher for a long time can be further maintained.

Here, examples of the silicon oxide include silicon monoxide (SiO), silicon dioxide (SiO ₂ ), and silicon oxide (Si ₃ O ₂ ).
On the other hand, examples of zirconium oxide include zirconium dioxide (ZrO ₂ ).

The surface of the catalyst particles has at least one of Ca, Ba, Mg, Ti, Al, Ce, Hf, La, and V in addition to Si and O of silicon oxide and Zr and O of zirconium oxide. An element (referred to as “element A”) may be present. Two or more of these may be included.
The presence of such an element A on the surface of the catalyst particles can further improve the steam reforming catalyst performance.
At this time, the element A is preferably dispersed uniformly over the entire surface of the catalyst particles.

  On the surface of the catalyst particles, silicon oxide, zirconium oxide, and two or more of element A may exist in a mixed state, silicon oxide, zirconium oxide, and element A May be present separately.

  The surface oxide may be present so as to cover the entire surface of the catalyst particle, may be present in a layer having a certain thickness, or may be partially present on the surface of the core particle. There may be a portion which is present in the surface oxide.

The surface coverage of silicon oxide or zirconium oxide (the ratio of the presence of silicon oxide or zirconium oxide over the entire surface of the catalyst particles as 100%) is 10% or more. From the viewpoint of sufficient steam reforming catalyst performance, it is preferably 20% or more or 100% or less from the viewpoint of the balance between steam reforming performance and heat resistance, and more preferably 35% or more and 75% or less. preferable.
The surface coverage of the silicon oxide or zirconium oxide and the surface coverage of the silicon compound or zirconium compound (when the silicon compound or zirconium compound is present on the entire surface of the catalyst particle is 100%, The same value as the silicon compound or zirconium compound). Therefore, in the Example mentioned later, the surface coverage of a silicon compound or a zirconium compound is calculated, and it is set as the surface coverage of a silicon oxide or a zirconium oxide. Thus, even in the case of 100% coverage, the gas flows through the microcracks.

In the present catalyst particle, the ratio of the content of silicon oxide and / or zirconium oxide to the core particle of 100 wt% is preferably 2 to 15 wt% in the state of the oxide before reduction activation.
In this catalyst particle, if the ratio of the content of silicon oxide or zirconium oxide or both to the core particle 100 wt% is 2 wt% or more, a heat-resistant effect can be expressed, and if it is 15 wt% or less, A homogeneous product can be obtained. Of these, 2 wt% or more or 5 wt% or less is particularly preferable.

As a method for causing the surface oxide to exist on the surface of the catalyst particles at such a ratio, for example, the core particle powder is impregnated in a solution containing silicon or zirconium or both, and dried and dried as necessary. It can be formed by firing. As described above, after the core particles are surface-treated using a solution containing silicon or zirconium or both, the silicon compound or the zirconium compound can be oxidized into silicon oxide or zirconium oxide by firing in the air. it can. For example, after surface-treating the core particles with a silane coupling agent or the like, the core particles are dried as necessary, and then heat-treated at 300 ° C. or higher, preferably 400 to 600 ° C. An oxide may be present.
In addition, the core particle powder is impregnated in a solution containing silicon or zirconium, for example, an ethanol solution of silicon alkoxide or zirconium alkoxide, dried as necessary, and then in a solution containing the element A as necessary. The catalyst particles may be impregnated and impregnated, dried as necessary, and then calcined to allow surface oxides to be present on the surfaces of the catalyst particles.

  In addition, components other than the above may exist on the surface of the catalyst particles. In particular, an amount of 1 wt% or less with respect to Si or Zr present on the surface of the present catalyst particles does not affect the effect of the present catalyst composition, and any component can be contained. be able to.

(Components other than the catalyst particles)
The present catalyst composition may contain other components in addition to the present catalyst particles.
Examples of other components include oxide particles containing a metal oxide such as alumina. By containing such oxide particles, the catalyst particles can be separated from each other, so that they can be prevented from sintering each other and the catalyst activity can be adjusted to a suitable level.

  Examples of such oxide particles include oxide particles containing oxides such as Al, Ti, Si, Zr, and Ce.

(BET specific surface area)
From the viewpoint that the BET specific surface area of the present catalyst composition can improve the steam reforming catalytic activity per unit catalyst mass, the steam reforming catalytically active component is reduced by reducing the present catalytic composition. in is preferably from 0.1m ² / g~100m ² / g, among others 0.5 m ² / g or more or 75 m ² / g or less, the at 5 m ² / g or more or 65 m ² / g or less among them Is particularly preferred.

  In order to adjust the specific surface area of the catalyst composition within the above range, a hydroxide of a steam reforming catalytically active component such as nickel hydroxide and an aqueous solution containing vanadium are mixed and subjected to an appropriate time under an appropriate condition. After allowing to stand and impregnating and adsorbing the vanadium on the hydroxide particles, drying by evaporation to dryness, or filtration and drying, firing at 300 to 600 ° C. (product temperature) in an air atmosphere (calcination) In this case, the specific surface area of the steam reforming catalyst active component can be adjusted by adjusting the firing temperature, the specific surface area of nickel hydroxide, and the like. However, it is not limited to such a method.

(Method for producing the present catalyst composition)
The present catalyst composition can be produced as follows. However, the manufacturing method described below is merely an example.

  An aqueous solution containing vanadium (for example, an ammonium vanadate aqueous solution) is mixed with the hydroxide powder or oxide powder of at least one element of Fe, Ni, Co, Ru, Rh, Pt, Pd, and Ir, Stir at room temperature to 50 ° C. for 15 minutes to 12 hours to impregnate and adsorb the vanadium on the hydroxide powder particles, and then heat to evaporate to dryness, or filter and dry to make it necessary. The catalyst particles can be obtained by pulverization accordingly.

  Next, when the surface oxide is present on the surface of the catalyst particles, the catalyst particles thus obtained are impregnated as core particles in a solution containing silicon or zirconium, or both. And then calcining so as to maintain 300 to 600 ° C. (product temperature) for 30 minutes to 6 hours in an air atmosphere, then press-molding as necessary, and 300 to 900 in an air atmosphere. The catalyst composition (powder or granular material) can be obtained by performing calcination so as to maintain the temperature (product temperature) for 30 minutes to 6 hours, and pulverizing and sieving as necessary.

<This catalyst>
A steam reforming catalyst (hereinafter referred to as “the present catalyst”) as an example of the embodiment of the present invention is a catalyst using the present catalyst composition.
The present catalyst is formed into an appropriate shape such as a pellet and can be used alone as a catalyst, or can be used as a form supported on a substrate made of ceramics or a metal material.

(Base material)
Examples of the material of the base material include refractory materials such as ceramics and metal materials such as ferritic stainless steel.
As the material of the ceramic substrate, refractory ceramic materials such as cordierite, cordierite-alpha alumina, silicon nitride, zircon mullite, alumina-silica magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, Examples include petalite, alpha alumina, and aluminosilicates.
Examples of the material of the metal substrate include a refractory metal, such as a corrosion resistant alloy mainly composed of stainless steel or iron.
Examples of the shape of the substrate include a honeycomb shape, a pellet shape, and a spherical shape.

(Production method of this catalyst)
The present catalyst is prepared by mixing and stirring the present catalyst composition, a binder and water to form a slurry. The obtained slurry is applied to a substrate such as a ceramic honeycomb body and fired to form a slurry on the surface of the substrate. Examples thereof include a method for forming a catalyst layer.

In addition, the present catalyst composition, a binder and water are mixed and stirred to form a slurry, and the resulting slurry is applied to a base material and then fired to form a catalyst layer on the base material surface. it can.
In addition, the method for manufacturing this catalyst can employ | adopt all the well-known methods, and is not limited to the said example.

  In any of the production methods, the catalyst layer may be a single layer or a multilayer of two or more layers.

<Explanation of words>
In the present specification, when expressed as “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, “X is preferably greater than X” or “preferably Y”. It also includes the meaning of “smaller”.
In addition, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is “preferably greater than X” or “preferably less than Y”. Includes intentions.

  Hereinafter, the present invention will be described in more detail based on examples and comparative examples.

<Comparative Example 1>
10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was calcined in the atmosphere at 550 ° C. for 3 hours to obtain catalyst powder. 1.6 g of 5 wt% PVA (polyvinyl alcohol) aqueous solution was added to 8 g of the catalyst powder, uniformly dispersed in a mortar, placed in a φ30 mm mold, and press-molded into a disk shape at a pressure of 90 kN.
The obtained disk-shaped molded body was fired in the atmosphere at 750 ° C. for 3 hours, measured for dimensions and weight, pulverized, passed through a sieve, and composed of catalytically active particle powder of 0.5 mm mesh to 4 mm mesh A steam reforming catalyst composition (sample) was obtained.

<Example 1>
0.19 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 17.5 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this ammonium vanadate aqueous solution, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added and stirred with a stirrer for 3 hours. Next, the mixture was heated to evaporate water, and the obtained solid was pulverized in a mortar and then calcined in the atmosphere at 550 ° C. for 3 hours to obtain catalyst powder. 1.6 g of 5 wt% PVA aqueous solution was added to 8 g of the catalyst powder, dispersed uniformly in a mortar, placed in a φ30 mm mold, and press-molded into a disk shape at a pressure of 90 kN.
The obtained disk-shaped molded body was fired in the atmosphere at 750 ° C. for 3 hours, measured for dimensions and weight, pulverized, and classified using a 4 mm mesh sieve and a 0.5 mm mesh sieve, A steam reforming catalyst composition (sample) comprising a V-added nickel-based catalytically active particle powder having a size of 0.5 mm to 4.0 mm was obtained.

<Example 2-1>
In Example 1, the mixing ratio of ammonium vanadate (NH ₄ VO ₃ ) and nickel hydroxide particle powder (specific surface area 120 m ² / g) was changed. That is, 0.39 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 36 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this aqueous solution of ammonium vanadate, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added. Except for this point, a steam reforming catalyst composition (sample) comprising a V-added nickel-based catalytically active particle powder was prepared in the same manner as in Example 1.

<Example 2-2>
In Example 1, the mixing ratio of ammonium vanadate (NH ₄ VO ₃ ) and nickel hydroxide particle powder (specific surface area 120 m ² / g) was changed. That is, 0.66 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 65 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this aqueous solution of ammonium vanadate, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added. Except for this point, a steam reforming catalyst composition (sample) comprising a V-added nickel-based catalytically active particle powder was prepared in the same manner as in Example 1.

<Example 2-3>
In Example 1, the mixing ratio of ammonium vanadate (NH ₄ VO ₃ ) and nickel hydroxide particle powder (specific surface area 120 m ² / g) was changed. That is, 1.25 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 115 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this aqueous solution of ammonium vanadate, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added. Except for this point, a steam reforming catalyst composition (sample) comprising a V-added nickel-based catalytically active particle powder was prepared in the same manner as in Example 1.

<Example 2-4>
In Example 1, the mixing ratio of ammonium vanadate (NH ₄ VO ₃ ) and nickel hydroxide particle powder (specific surface area 120 m ² / g) was changed. That is, 2.23 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 205 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this aqueous solution of ammonium vanadate, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added. Except for this point, a steam reforming catalyst composition (sample) comprising a V-added nickel-based catalytically active particle powder was prepared in the same manner as in Example 1.

<Example 2-5>
In Example 1, the mixing ratio of ammonium vanadate (NH ₄ VO ₃ ) and nickel hydroxide particle powder (specific surface area 120 m ² / g) was changed. That is, 5.4 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 500 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this aqueous solution of ammonium vanadate, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added. Except for this point, a steam reforming catalyst composition (sample) comprising a V-added nickel-based catalytically active particle powder was prepared in the same manner as in Example 1.

<Example 2-6>
In Example 1, the mixing ratio of ammonium vanadate (NH ₄ VO ₃ ) and nickel hydroxide particle powder (specific surface area 120 m ² / g) was changed. That is, 8.5 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 770 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this aqueous solution of ammonium vanadate, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added. Except for this point, a steam reforming catalyst composition (sample) comprising a V-added nickel-based catalytically active particle powder was prepared in the same manner as in Example 1.

<Example 2-7>
In Example 1, the mixing ratio of ammonium vanadate (NH ₄ VO ₃ ) and nickel hydroxide particle powder (specific surface area 120 m ² / g) was changed. That is, 12.6 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 1160 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this aqueous solution of ammonium vanadate, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added. Except for this point, a steam reforming catalyst composition (sample) comprising a V-added nickel-based catalytically active particle powder was prepared in the same manner as in Example 1.

<Example 3>
0.66 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 65 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this ammonium vanadate aqueous solution, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added and stirred with a stirrer for 3 hours. Next, moisture was evaporated by heating, and the obtained solid was pulverized in a mortar to obtain a powder sample. To this powder sample, 0.78 g of a silane coupling agent (3-aminopropyltriethoxysilane, “KBE-903” manufactured by Shin-Etsu Silicone Co., Ltd., molecular weight 221.4) was added to 10 mL of water, and an aqueous precursor solution stirred uniformly was added. In addition, the mixture was stirred with a stirrer for 3 hours to uniformly coat the powder, and then the moisture was evaporated by heating to dry the sample.
The obtained solid sample was pulverized in a mortar and then calcined in the atmosphere at 550 ° C. for 3 hours to obtain catalyst powder. 1.6 g of 5 wt% PVA aqueous solution was added to 8 g of the catalyst powder, dispersed uniformly in a mortar, placed in a φ30 mm mold, and press-molded into a disk shape at a pressure of 90 kN.
The obtained disk-shaped molded body was fired in the atmosphere at 750 ° C. for 3 hours, measured for dimensions and weight, pulverized, and classified using a 4 mm mesh sieve and a 0.5 mm mesh sieve, A steam reforming catalyst composition (sample) comprising “V-added nickel-based catalytically active particle powder having silicon oxide present on the surface” having a size of 0.5 mm to 4.0 mm was obtained.

<Example 4>
In the preparation of the aqueous precursor solution of Example 3, in the same manner as in Example 3 except that 0.74 g of zirconium acetate (molecular weight 327.4) was added to 10 mL of water instead of 0.78 g of the silane coupling agent, “ A steam reforming catalyst composition (sample) comprising “V-added nickel-based catalytically active particle powder having zirconium oxide on the surface” was obtained.

<Example 5>
In the preparation of the aqueous precursor solution of Example 3, instead of adding 0.78 g of a silane coupling agent (3-aminopropyltriethoxysilane, “KBE-903” manufactured by Shin-Etsu Silicone) to 10 mL of water, a silane coupling agent ( In the same manner as in Example 3, except that 0.78 g of “KBE-903” manufactured by Shin-Etsu Silicone Co., Ltd., molecular weight 221.4) and 0.74 g of zirconium acetate (molecular weight 327.4) were added to 10 mL of water, “silicon oxide” And a steam reforming catalyst composition (sample) comprising “V-added nickel-based catalytically active particle powder having zirconium oxide on the surface”.

<Example 6>
0.66 g of ammonium vanadate (NH ₄ VO ₃ ) was dissolved in 65 mL of pure water at 50 ° C. to prepare an ammonium vanadate aqueous solution. To this aqueous solution of ammonium vanadate, 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added and stirred for 3 hours with a stirrer, then 0.1 mL of Ru 50 g / L ruthenium nitrate solution was added, and further stirred for 1 hour. Vanadium and ruthenium were sufficiently adsorbed on the surface of the nickel hydroxide particles. Next, it was heated to evaporate water by evaporation to dryness, and the obtained solid was pulverized in a mortar to obtain a powder sample. To this powder sample, 0.78 g of a silane coupling agent (3-aminopropyltriethoxysilane, “KBE-903” manufactured by Shin-Etsu Silicone) was added to 10 mL of water, and 0.74 g of zirconium acetate (molecular weight 327.4) was added. In addition, the precursor aqueous solution that was uniformly stirred was added, stirred for 3 hours with a stirrer to uniformly coat the powder, and then the water was evaporated by heating and dried to obtain a solid sample.
The obtained solid sample was pulverized in a mortar and then calcined in the atmosphere at 550 ° C. for 3 hours to obtain catalyst powder. 1.6 g of 5 wt% PVA aqueous solution was added to 8 g of the catalyst powder, dispersed uniformly in a mortar, placed in a φ30 mm mold, and press-molded into a disk shape at a pressure of 90 kN.
The obtained disk-shaped molded body was fired in the atmosphere at 750 ° C. for 3 hours, measured for dimensions and weight, pulverized, and classified using a 4 mm mesh sieve and a 0.5 mm mesh sieve, A steam reforming catalyst composition (sample) composed of “V · Ru-added nickel-based catalytically active particle powder having silicon oxide and zirconium oxide existing on the surface” having a size of 0.5 mm to 4.0 mm was obtained.

<Example 7>
In Example 5, the mixing ratio of the precursor aqueous solution was adjusted to change the amount of silicon oxide present on the particle surface. That is, the silane coupling agent (3-aminopropyltriethoxysilane, “KBE-903” manufactured by Shin-Etsu Silicone Co., Ltd., molecular weight 221.4) was changed to 1.56 g, and zirconium acetate (molecular weight 327.4) was changed to 1.48 g. . Except for this point, a steam reforming catalyst composition (sample) composed of “V-added nickel-based catalytically active particle powder having silicon oxide and zirconium oxide present on the surface” was obtained in the same manner as in Example 5.

<Evaluation of steam reforming performance>
Using the fuel reforming evaluation apparatus shown in FIG. 1, the amount of hydrogen (H ₂ %) generated in the steam reforming reaction by the steam reforming catalyst composition (sample) obtained in each of the examples and comparative examples is measured. Thus, the steam reforming performance was evaluated.
As shown in FIG. 1, this fuel reforming evaluation apparatus is a city gas (methane 89 to 90 vol%, ethane 4 to 6 vol%, propane 4 to 5 vol%, butane less than 1 vol% supplied as a gas fuel 1 from a cylinder. ) And the pure water in the pure water tank 3 can be adjusted in flow rate by the gas mass flow controller 2 and the liquid mass flow controller 4, respectively. The pure water passes through the vaporizer 6 in the electric furnace 5 and becomes water vapor, which is mixed with gaseous fuel in the fuel gas / water vapor mixing section 7 and sent to the reforming catalyst 9 sealed in a stainless steel container in the electric furnace 8. The gas reformed by the reforming catalyst 9 is exhausted through a bubbler 11.
A part of the exhaust gas is sucked by a pump built in a gas chromatograph (hereinafter referred to as “GC”) 13, and the reformed gas that has passed through the water removing device 12 is quantified by the GC 13. At this time, the hydrogen amount (H ₂ %) with respect to the total gas amount was measured and evaluated.

(Gas reforming evaluation test)
5 g of the steam reforming catalyst composition (sample) obtained in each of the examples and comparative examples was placed in the reformer, and the interior of the reformer was replaced with nitrogen gas. Next, in order to activate the catalyst, the fuel reforming section was heated in the electric furnace 8, and when the catalyst temperature reached 500 ° C., the supply of city gas and water vapor was started and the reduction activation process was started. At this time, the flow rate of the fuel gas was set to a space velocity (SV) of 9000 h ⁻¹ and the ratio of city gas to water vapor (S / C) was set to 2.5.
The temperature was further raised and maintained for 30 minutes when the catalyst temperature reached 550 ° C., then the temperature was raised again and heated at 750 ° C. for 1 minute to complete the reduction activation treatment.
Thereafter, the temperature was lowered and kept at 550 ° C. for 15 minutes, and then the hydrogen generation amount was measured by a gas chromatograph (Fresh value).

  For the accelerated acceleration test of the catalyst performance, after measuring the Fresh value as described above, the S / C ratio was increased to 4.0, the temperature was raised to 750 ° C. and maintained at 750 ° C. for 90 minutes, and then S The amount of hydrogen was measured (Aged value) when 10 minutes had elapsed after the temperature was lowered to 550 ° C. after returning to the / C ratio of 2.5.

<Sintering density>
As described in each example, the diameter, height and weight of the disk-shaped catalyst pellet sintered body in the oxide state (before reduction activation treatment) were measured, and the sintered density (g / cm ³ ) was determined. Calculated.

<BET>
About the steam reforming catalyst composition (sample) obtained in each Example / Comparative Example, a specific surface area pore distribution measuring device (“SA3100” manufactured by BECKMAN COULTER Co., Ltd.) was used to produce fuel by N ₂ gas adsorption method. The BET specific surface area (m ² / g) measured after the evaluation of the steam reforming performance (including the deterioration acceleration test) by the reforming evaluation apparatus was taken as the value after Aged.

<Confirmation of existence of nickel oxide phase of nickel vanadium>
Steam reforming catalyst composition (sample before gas evaluation test, referred to as “pre”) obtained in the above examples and comparative examples, and after the gas reforming evaluation test, that is, reduction activation treatment, measurement of hydrogen generation amount X-ray diffraction analyzer (Rigaku Corporation) for each of the steam reforming catalyst compositions (referred to as “after Aged”) recovered after the samples that had undergone the deterioration acceleration test and the hydrogen generation amount measurement were heated to room temperature in a nitrogen atmosphere. X-ray diffraction (XRD) measurement was performed using a product manufactured by RINT TTRIII) (see FIGS. 3 to 6).
And the X-ray diffraction pattern obtained (from the figure, was there a composite oxide phase of nickel vanadium attributed to Ni ₃ (VO ₄ ) O ₂ , (V _1.34 Ni _0.66 ) O _3, etc.) In the table, the composite oxide phase of nickel vanadium is simply indicated as “composite oxide” and evaluated as “Yes” when the presence was confirmed, and “None” when it was not confirmed. .

<Scanning electron microscope (SEM) observation>
The catalytically active particles after the gas reforming evaluation test of the steam reforming catalyst compositions obtained in the above Examples and Comparative Examples (after Ageing) were observed with a scanning electron microscope (XL30-SFEG manufactured by SEM / FEICOMPANY). (See FIGS. 7 to 15).

<Surface coverage>
The surface coverage (= additional amount of surface treatment agent (g) × 100 below) can be calculated from the following two formulas.
Minimum covering area (m ² /g)=6.02×10 ²³ × 13 × 10 ⁻²⁰ / Surface treatment agent molecular weight Surface treatment agent addition amount (g) = Ni (OH) ₂ weight (g) × Ni (OH) ₂ Specific surface area (m ² / g) / Minimum covered area (m ² / g)
Here, the surface treatment agent refers to the silane coupling agent and zirconium acetate used in the above examples.
For Examples 6 and 7 using two types of surface treatment agents, silane coupling agent and zirconium acetate, the average molecular weight corresponding to the molar ratio of both was calculated as the surface treatment agent molecular weight.
In Table 2, the surface coverage of silicon oxide (silane coupling agent) or zirconium oxide (zirconium acetate) or a mixture of silicon oxide and zirconium oxide is shown as “coverage”.

Each steam reforming catalyst composition (sample) obtained in the above Example 1, Examples 2-1 to 2-2 and Examples 3 to 7 is used as EDX of FE-SEM (manufactured by JSM-7001F / JEOL). As a result, in any steam reforming catalyst composition, vanadium is present in a larger amount on the surface than in the inside of the catalytically active particles, and is not scattered on the surface of the catalytically active particles. It was confirmed that they existed in a dispersed state.
Further, from the above examples and the test results conducted by the inventors so far, as in Comparative Example 1, the nickel-based catalytically active particle powder not containing vanadium was sintered from the stage of the reduction activation treatment at 550 ° C. It has been confirmed that the catalytic activity is reduced due to the progress of.

As a result of observing the catalytically active particles (after Aged) of the steam reforming catalyst compositions obtained in the Examples and Comparative Examples after the gas reforming evaluation test with a scanning electron microscope (see FIGS. 7 to 15), It was found that Comparative Example 1 was metallized and melted in a reducing atmosphere (FIG. 7).
On the other hand, in Example 1, the effect of adding vanadium (V) suppresses an increase in particle diameter due to sintering (FIG. 8), and in Example 2-1, sintering is suppressed, and the grain boundary is reduced. It was found that a gap exists (FIG. 9). About all of Examples 2-2 to 2-4, it turned out that the grain growth was suppressed by the effect of addition of V (FIGS. 10-12). In any of Examples 2-5 to 2-7, it was found that even when V was further added, the effect of suppressing grain growth was sustained, and a decrease in catalyst performance could be prevented (FIGS. 13 to 15).

When the sample after the catalyst performance deterioration acceleration test of Comparative Example 1 was collected, it was grayed and hard sintered, and it was difficult to grind in a mortar.
On the other hand, it was found that by adding vanadium, the reduction of the catalyst activity can be suppressed by suppressing sintering not only during the reduction activation treatment at 550 ° C. but also during the reforming reaction. Moreover, since each sample of the Example after the catalyst performance deterioration acceleration test was black and was easily pulverized in a mortar, it was found that sintering did not proceed.

In addition, a part of each steam reforming catalyst composition (sample) obtained in Examples 3 to 7 was collected and distributed on the nickel particle surface by EDX of FE-SEM (manufactured by JSM-7001F / JEOL). As a result, it was confirmed that silicon and oxygen, zirconium and oxygen, or silicon, zirconium and oxygen were uniformly distributed on the surfaces of the nickel particles, that is, the catalytically active particles.
Thus, the presence of an appropriate amount of silicon oxide and / or zirconium oxide on the surface of the catalytically active particles further reduces the sintering at 550 ° C. and further during the reforming reaction. It can be suppressed, and it has been found that a decrease in catalyst activity can be further suppressed. In particular, it has been found that the catalyst performance after reduction and exposure to a high temperature environment of 550 ° C. or higher for a long time can be maintained and thermal degradation can be suppressed. Such an effect is added to the anchor effect in which the surface oxide restricts the movement of the material constituting the catalyst particles when silicon oxide and / or zirconium oxide are present in an appropriate amount on the surface of the catalytically active particles. It can be inferred that sintering is suppressed because the Ni component and the V component form a compound having a high specific surface area.

  As described above, the presence of silicon oxide or zirconium oxide or both on the surface of the catalytically active particles can suppress thermal degradation. On the other hand, silicon oxide or zirconium oxide or these It was also found that by increasing the vanadium content by a specific amount without both being present on the surface of the catalytically active particles, the thermal characteristics are improved and the thermal degradation can be similarly suppressed. However, when the content of vanadium is increased by a specific amount without the presence of silicon oxide or zirconium oxide or both on the particle surface, a large amount of expensive vanadium must be contained, and the vanadium component is segregated. And tends to be uneven. Therefore, in view of workability and cost, it can be considered that it is preferable that silicon oxide or zirconium oxide or both exist on the surface of the catalytically active particles.

1 Gaseous fuel (city gas)
2 Gas mass flow controller 3 Pure water tank 4 Liquid mass flow controller 5 Electric furnace (300 ℃ fixed)
6 Vaporizer 7 Fuel gas / steam mixing section 8 Electric furnace 9 Reforming catalyst 10 Reforming catalyst temperature measurement thermocouple 11 Bubbler 12 Moisture remover 13 Gas chromatograph

Claims (8)

  A steam reforming catalyst composition comprising catalytically active particles containing a steam reforming catalyst active component and vanadium.   2. The steam reforming catalyst composition according to claim 1, wherein vanadium is contained at a ratio of 1 mol% or more with respect to 100 mol% of the steam reforming catalyst active component.   The steam reforming catalyst according to claim 1 or 2, wherein the steam reforming catalyst active component contains at least one element of Fe, Ni, Co, Ru, Rh, Pt, Pd and Ir. Composition.   The steam reforming catalytically active component contains at least one element of Fe, Ni, Co, Ru, Rh, Pt, Pd, and Ir as a metal, an oxide, a mixture thereof, or a solid solution thereof. The steam reforming catalyst composition according to any one of claims 1 to 3.   The steam reforming catalyst composition according to any one of claims 1 to 4, wherein vanadium is present on the surface of the catalytically active particles.   The steam reforming catalyst composition according to any one of claims 1 to 5, wherein silicon oxide and / or zirconium oxide is present on the surface of the catalytically active particles.   The steam reforming catalyst formed by shape | molding the steam reforming catalyst composition in any one of Claims 1-6 in a pellet form.   The steam reforming catalyst provided with the structure which carry | supports the steam reforming catalyst composition in any one of Claims 1-6 on a base material.