WO2016047504A1

WO2016047504A1 - Steam reforming catalyst composition and steam reforming catalyst

Info

Publication number: WO2016047504A1
Application number: PCT/JP2015/076168
Authority: WO
Inventors: 憲之高橋; 林　克彦
Original assignee: 三井金属鉱業株式会社
Priority date: 2014-09-24
Filing date: 2015-09-15
Publication date: 2016-03-31
Also published as: JP6442519B2; JPWO2016047504A1

Abstract

The purpose of the present invention is to provide a novel steam reforming catalyst composition in which catalyst performance does not decrease even in reforming reactions and reduction treatments at temperatures of 500 °C or more. Provided is a steam reforming catalyst composition comprising catalytically active particles that contain: a steam reforming catalytically active component that has the effect of promoting the steam reforming reaction; and vanadium. Adding vanadium makes it possible to minimize sintering during a reforming reaction or a reduction treatment at temperatures of 500 °C or more and thereby minimize the deterioration of catalyst performance without decreasing the original catalyst performance of the steam reforming catalytically active component.

Description

Steam reforming catalyst composition and steam reforming catalyst

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

A fuel cell is a cell that converts chemical energy into electrical energy by electrochemically reacting hydrogen and oxygen, and as the hydrogen source, hydrogen obtained by reforming city gas, hydrocarbons, etc. It's being used. The 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 etc. 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 formula (1) The reaction to form hydrogen (H ₂ ) by the chemical reaction to proceed as the main reaction. Further, since carbon monoxide (CO) obtained by the reaction of the formula (1) combines with a large amount of water vapor, a reaction to generate hydrogen further proceeds by the water gas shift reaction (see the formula (2)) .

(1) ... C _n H _m + _n H ₂ O → n CO + (m / 2 + n) H ₂
(2) ... CO + H ₂ O → CO ₂ + H ₂

Conventionally, as a reforming catalyst used for such a steam reforming reaction, a nickel-based catalyst having a transition metal element represented by nickel as a catalytically active component is known.

For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-74396), Cu, Co, Fe, Ni, Mn, Zn, Sn, Cd, Pd, Cu, Co, Fe, Ni, Mn, Zn, Sn, Cd, Pd, and the like as metal particle dispersed oxides that can function as catalysts for steam reforming. “Reducible metal oxides” that can be reduced to metal under hydrogen atmosphere from room temperature to 1500 ° C., such as oxides of Ag, Ru, Rh, Mo, W and In; Al, Mg, Si, Zr, Ti, Hf And oxide particles such as oxides of Ce, etc., which are composed of a solid phase with a “non-reducible metal oxide” that is not reduced to metal under a hydrogen atmosphere at room temperature to 1500 ° C. A metal particle dispersed oxide is disclosed, in which metal particles are deposited and internal metal particles are deposited inside the oxide particles.

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

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

By the way, regarding the conventionally proposed transition metal-based catalyst in which a transition metal element represented by nickel is used as a steam reforming catalyst active component, it has been necessary to further improve the steam reforming performance.
In addition, in order to use this kind of transition metal catalyst as a steam reforming catalyst, it is necessary to reduce and activate it before using it. However, when this type of catalyst is reduced at a temperature of 500 ° C. or higher, the phase transition of the oxide to the metal phase causes sintering (sintering), so the activity of the active component of the steam reforming catalyst decreases. The problem is that the catalyst performance that the steam reforming catalyst active component originally has can not be exhibited.

Therefore, the present invention is superior in steam reforming performance to conventionally proposed transition metal catalysts comprising a transition metal element as a steam reforming catalyst active component, and further, reduction treatment at a temperature of 500 ° C. or higher And, in the reforming reaction, it is intended to propose a new steam reforming catalyst composition in which the catalyst performance does not decrease.

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 conventionally proposed transition metal catalysts by containing vanadium and is reduced at a temperature of 500 ° C. or more. It is also possible to suppress the deterioration of the catalyst performance by suppressing the sintering during the treatment or the reforming reaction.

It is the block diagram which showed the outline of the fuel-reforming evaluation apparatus used by the gas-reforming evaluation test of the 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, (b) in the particles It is an enlarged photograph showing the distribution of oxygen (O), (c) an enlarged photograph showing the distribution of vanadium (V) in the particle, and (d) shows the distribution of nickel in the particle It is an enlarged picture. Note that “Grey”, “K” and “L” at the upper left of FIG. 2 relate to the 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 the excited electrons. It is a 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 a 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 a 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 a 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. It is a SEM image of the steam reforming catalyst composition (sample after gas evaluation test, referred to as “aged”) obtained in Comparative 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 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 (sample after gas evaluation test, referred to as "aged") obtained in Example 2-4. 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 embodiments described below.

<The present 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 comprises catalytically active particles (hereinafter referred to as "the present catalyst particles") containing a steam reforming catalyst active component and vanadium. And a steam reforming catalyst composition comprising

The form of the present catalyst composition may be any form such as powder, slurry, pellet, layered product and the like.

(This catalyst particle)
The present catalyst particles are catalytically active particles containing a steam reforming catalytically active component and vanadium.
Vanadium reacts with the steam reforming catalyst active component to form a composite oxide. This complex oxide is gradually reduced by the reduction treatment for catalyst activation to express activity. The reduced active component is eventually deactivated by heat sintering, but due to hydrogen in the reforming reaction, the remaining complex oxide is newly reduced to exhibit activity. By repeating this cycle, the active ingredient can be supplied and as a result, the life of the catalyst can be extended.
At this time, by incorporating vanadium in the catalyst particles containing the steam reforming catalytic active component such as nickel, reduction of the specific surface area after reduction activation is suppressed and the steam reforming performance is improved as compared to the case where vanadium is not contained. It is possible to further suppress the deterioration of the performance due to the sintering in the reduction activation treatment or the reforming reaction at a temperature of 500 ° C. or more.

The catalyst particles may be aggregated particles in which primary particles are aggregated, or particles in which the primary particles are monodispersed. As an example, mention may be made of particles having a structure in which silicon oxide or zirconium oxide is present on the surface of the primary particles, as described later, in which granular or needle-like primary particles aggregate to form aggregated particles. it can.

(Steam reforming catalyst active ingredient)
As the steam reforming catalyst active component, an element known to have an effect of promoting a steam reforming reaction can be used. For example, at least one element of Fe, Ni, Co, Ru, Rh, Pt, Pd and Ir can be mentioned. 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 them, it is preferable to contain Ni, or Ni and Ru or Rh. As described above, when Ni and Ru or Rh are contained, Ru or Rh is preferable in that it can further promote the steam reforming reaction and the conditions for reduction activation of the present catalyst composition can be relaxed.

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

(vanadium)
In the catalyst particles, vanadium is preferably present in the form of an oxide, a metal, or a mixture thereof, or a solid solution thereof. That is, it exists as an oxide in the 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 to form an alloy, to form a solid solution, or to exist in the form of a mixture of these.

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

When the catalyst particles contain vanadium, sintering can be effectively suppressed. In order not to degrade the activity of nickel which is a steam reforming catalyst active component, it is preferable to contain vanadium in a proportion of 1 mol% or more with respect to 100 mol% of the steam reforming catalyst active component.
However, when the vanadium content is too high, when using the aqueous solution containing vanadium as described above, not only there is a possibility that the workability may be reduced, but vanadium pentoxide is formed when producing the catalyst particles. Since there is a possibility of melting at the time of catalyst calcination, it is not preferable that the content of vanadium is too high.
From this point of view, the vanadium content is preferably contained in a proportion of 1 mol% or more with respect to 100 mol% of the steam reforming catalyst active component, more preferably 200 mol% or less, among them 2 mol% or more or 100 mol% or less Among them, it is particularly preferable to contain at a ratio of 3 mol% or more or 45 mol% or less.

(Surface condition)
The catalyst particles may have silicon oxide or zirconium oxide or both on the particle surface.
The catalyst particles are formed by the presence of a suitable amount of silicon oxide or zirconium oxide or both (also referred to as "surface oxide") on the surface of the present catalyst particles (also referred to as "core particles") containing vanadium. In order to exert the anchor effect that the surface oxide restricts the movement of the constituent material, reduction activation treatment or reforming reaction is performed at a temperature of 500 ° C. or more without lowering the catalytic performance inherent to the present catalyst particles. It is possible to further suppress the sintering at the time. In particular, it is possible to further maintain the steam reforming catalyst performance after being exposed to a reducing environment or a high temperature environment of 550 ° C. or more for a long time.

Here, in addition to silicon monoxide (SiO) and silicon dioxide (SiO ₂ ), examples of the silicon oxide include silicon suboxide (Si ₃ O ₂ ) and the like.
On the other hand, zirconium dioxide (ZrO ₂ ) can be mentioned as the zirconium oxide.

In addition to Si and O of silicon oxide and Zr and O of zirconium oxide, at least one of Ca, Ba, Mg, Ti, Al, Ce, Hf, La, and V is provided on the surface of the present catalyst particles. 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 present catalyst particles can further enhance the steam reforming catalyst performance.
Under the present circumstances, it is preferable that the said element A is disperse | distributed uniformly over the whole surface of this catalyst particle.

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

The surface oxide may be present so as to cover the entire surface of the present catalyst particles, may be present in a layer having a certain thickness, or may be partially present on the surface of the core particles. There may be portions where the surface oxide is not present.

The surface coverage of silicon oxide or zirconium oxide (the ratio of 100% when silicon oxide or zirconium oxide is present on the entire surface of the catalyst particle) is 10% or more. It is preferable from the viewpoint of achieving sufficient steam reforming catalyst performance, and in particular, 20% or more or 100% or less from the viewpoint of the balance between steam reforming performance and heat resistance, among them 35% or more or 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 ratio of presence of the silicon compound or the zirconium compound is the same value. Therefore, in the examples described later, the surface coverage of the silicon compound or zirconium compound is calculated to be the surface coverage of the silicon oxide or zirconium oxide. Thus, even in the case of 100% coating, the gas flows through the micro cracks.

In the catalyst particles, the ratio of the content of silicon oxide or zirconium oxide or both to 100 wt% of the core particles is preferably 2 to 15 wt% in the oxide state before reduction activation.
In the catalyst particles, when the ratio of the content of silicon oxide or zirconium oxide or both of them to 100 wt% of core particles is 2 wt% or more, the heat resistance effect can be exhibited, and if it is 15 wt% or less, A homogeneous product can be obtained. Among these, 2 wt% or more or 5 wt% or less is particularly preferable.

As a method of causing surface oxides to exist on the surface of the present catalyst particles in such a ratio, for example, the core particle powder is put in a solution containing silicon or zirconium or both and impregnated, and optionally dried and It can be formed by firing. Thus, the silicon oxide or the zirconium compound can be oxidized to the silicon oxide or the zirconium oxide by surface-treating the core particle with a solution containing silicon or zirconium or both of them and then firing in the air. it can. For example, after surface-treating core particles using a silane coupling agent etc., they are dried if necessary, and then heat-treated at 300 ° C. or higher, preferably 400 to 600 ° C., to form the surface of the present catalyst particles. 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 present catalyst particles may be impregnated with the catalyst particles, dried if necessary, and then fired 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 present catalyst particles. In particular, an amount of 1 wt% or less based on Si or Zr present on the surface of the present catalyst particles does not affect the effect of the present catalyst composition, and allows any component to be contained. be able to.

(Components other than this catalyst particle)
The present catalyst composition may contain other components in addition to the present catalyst particles.
As another component, the oxide particle containing metal oxides, such as an alumina, can be mentioned, for example. By containing such oxide particles, the present catalyst particles can be separated from each other, so that sintering can be prevented and the catalyst activity can be adjusted to a suitable level.

As such an oxide particle, an oxide particle containing oxides, such as Al, Ti, Si, Zr, and Ce, can be mentioned, for example.

(BET specific surface area)
From the viewpoint that the BET specific surface area of the present catalyst composition can improve the steam reforming catalyst activity per unit catalyst mass, a state in which the steam reforming catalyst active component is reduced by subjecting the present catalyst composition to a reduction treatment 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 present catalyst composition to the above range, a hydroxide of a steam reforming catalyst active component such as nickel hydroxide and an aqueous solution containing vanadium are mixed, and an appropriate time is obtained under appropriate conditions. The mixture is allowed to stand so that the particles of the hydroxide are impregnated and adsorbed with the particles of the hydroxide, dried by evaporation to dryness, or filtered and dried, and then calcined at 300 to 600 ° C. (product temperature) in the air atmosphere (calcination) In this case, the specific surface area of the steam reforming catalyst active component can be adjusted by adjusting the calcination temperature, the specific surface area of the nickel hydroxide and the like. However, it is not limited to such a method.

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

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

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

<This catalyst>
A steam reforming catalyst (hereinafter, referred to as "the present catalyst") as an example of an embodiment of the present invention is a catalyst formed using the present catalyst composition.
The present catalyst can be 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 a ceramic or a metal material.

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

(Manufacturing method of this catalyst)
The present catalyst is prepared by mixing and stirring the present catalyst composition, a binder and water to obtain a slurry, and applying the obtained slurry to a base material such as a ceramic honeycomb body, and calcining the obtained slurry on the base material surface. The method etc. which form a catalyst layer can be mentioned.

In addition, a method of mixing the present catalyst composition, a binder and water with stirring to form a slurry, applying the obtained slurry to a substrate, and calcining this to form a catalyst layer on the surface of the substrate is also mentioned. it can.
In addition, it is possible to employ | adopt all well-known methods for the method for manufacturing this catalyst, and it 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 the phrase>
In the present specification, when expressing as “X to Y” (where X and Y are arbitrary numbers), “preferably more than X” or “preferably Y” with the meaning of “X or more and Y or less” unless otherwise stated. Also includes the meaning of "smaller".
Also, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), “greater than X is preferable” or “preferably less than Y” It also includes the intention.

Hereinafter, the present invention will be further described in 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 at 550 ° C. in the atmosphere for 3 hours to obtain a catalyst powder. To 8 g of the catalyst powder, 1.6 g of a 5 wt% PVA (polyvinyl alcohol) aqueous solution was added, dispersed uniformly in a mortar, placed in a 30 30 mm mold, and pressed into a disc at a pressure of 90 kN.
The obtained disk-like molded product is calcined at 750 ° C. in the atmosphere for 3 hours, and after measuring its size and weight, it is crushed and passed through a sieve and is composed of catalytic active particle powder of 0.5 mm mesh or more and 4 mm mesh or less 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 aqueous ammonium vanadate solution. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to this aqueous solution of ammonium vanadate, and the mixture was stirred for 3 hours with a stirrer. Next, the resultant was heated to evaporate the water content, and the obtained solid was pulverized in a mortar and calcined at 550 ° C. in the atmosphere for 3 hours to obtain a catalyst powder. 1.6 g of a 5 wt% PVA aqueous solution was added to 8 g of the catalyst powder, dispersed uniformly in a mortar, placed in a 金 30 mm mold, and pressed into a disc at a pressure of 90 kN.
The obtained disk-like molded body is fired at 750 ° C. in the atmosphere for 3 hours to measure its size and weight, then crushed and classified using a 4 mm mesh sieve and a 0.5 mm mesh sieve, A steam reforming catalyst composition (sample) consisting of V-added nickel-based catalyst active particles 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 aqueous ammonium vanadate solution. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to the ammonium vanadate aqueous solution. A steam reforming catalyst composition (sample) comprising a V-added nickel-based catalyst active particle powder was prepared in the same manner as in Example 1 except for this point.

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 aqueous ammonium vanadate solution. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to the ammonium vanadate aqueous solution. A steam reforming catalyst composition (sample) comprising a V-added nickel-based catalyst active particle powder was prepared in the same manner as in Example 1 except for this point.

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 aqueous ammonium vanadate solution. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to the ammonium vanadate aqueous solution. A steam reforming catalyst composition (sample) comprising a V-added nickel-based catalyst active particle powder was prepared in the same manner as in Example 1 except for this point.

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 aqueous ammonium vanadate solution. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to the ammonium vanadate aqueous solution. A steam reforming catalyst composition (sample) comprising a V-added nickel-based catalyst active particle powder was prepared in the same manner as in Example 1 except for this point.

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 aqueous ammonium vanadate solution. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to the ammonium vanadate aqueous solution. A steam reforming catalyst composition (sample) comprising a V-added nickel-based catalyst active particle powder was prepared in the same manner as in Example 1 except for this point.

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 aqueous ammonium vanadate solution. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to the ammonium vanadate aqueous solution. A steam reforming catalyst composition (sample) comprising a V-added nickel-based catalyst active particle powder was prepared in the same manner as in Example 1 except for this point.

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 aqueous ammonium vanadate solution. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to the ammonium vanadate aqueous solution. A steam reforming catalyst composition (sample) comprising a V-added nickel-based catalyst active particle powder was prepared in the same manner as in Example 1 except for this point.

Example 3
An aqueous solution of ammonium vanadate was prepared by dissolving 0.66 g of ammonium vanadate (NH ₄ VO ₃ ) in 65 mL of pure water at 50 ° C. 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) was added to this aqueous solution of ammonium vanadate, and the mixture was stirred for 3 hours with a stirrer. Next, the water was evaporated by heating, and the obtained solid was crushed 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 the precursor aqueous solution was uniformly stirred In addition, after stirring with a stirrer for 3 hours to uniformly coat the powder, the water was evaporated by heating to dry the sample.
The obtained solid sample was pulverized in a mortar and calcined at 550 ° C. in the atmosphere for 3 hours to obtain a catalyst powder. 1.6 g of a 5 wt% PVA aqueous solution was added to 8 g of the catalyst powder, dispersed uniformly in a mortar, placed in a 金 30 mm mold, and pressed into a disc at a pressure of 90 kN.
The obtained disk-like molded body is fired at 750 ° C. in the atmosphere for 3 hours to measure its size and weight, then crushed and classified using a 4 mm mesh sieve and a 0.5 mm mesh sieve, A steam reforming catalyst composition (sample) composed of “V-added nickel-based catalyst active particle powder having silicon oxide 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, the procedure of Example 3 was repeated, 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) was obtained comprising “V-added nickel-based catalytically active particle powder having zirconium oxide on the surface”.

Example 5
In 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 Co., Ltd.) to 10 mL of water, a silane coupling agent ( “Silicon oxide” 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 And a steam reforming catalyst composition (sample) comprising “V-added nickel-based catalyst active particle powder having zirconium oxide on the surface”.

Example 6
An aqueous solution of ammonium vanadate was prepared by dissolving 0.66 g of ammonium vanadate (NH ₄ VO ₃ ) in 65 mL of pure water at 50 ° C. After adding 10 g of nickel hydroxide particle powder (specific surface area 120 m ² / g) to this ammonium vanadate aqueous solution and stirring with a stirrer for 3 hours, 0.1 mL of a ruthenium nitrate solution of Ru 50 g / L is added and stirring is further performed for 1 hour. The vanadium and ruthenium were sufficiently adsorbed on the surface of the nickel hydroxide particles. Next, the resultant was heated and evaporated to dryness to evaporate the water content, and the obtained solid was ground 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.) is added to 10 mL of water, and 0.74 g of zirconium acetate (molecular weight 327.4) is further added In addition, a uniformly stirred precursor aqueous solution was added, and stirred with a stirrer for 3 hours to uniformly coat the powder, and then the water was evaporated by heating and dried to obtain a solid sample sample.
The obtained solid sample was pulverized in a mortar and calcined at 550 ° C. in the atmosphere for 3 hours to obtain a catalyst powder. 1.6 g of a 5 wt% PVA aqueous solution was added to 8 g of the catalyst powder, dispersed uniformly in a mortar, placed in a 金 30 mm mold, and pressed into a disc at a pressure of 90 kN.
The obtained disk-like molded body is fired at 750 ° C. in the atmosphere for 3 hours to measure its size and weight, then crushed and classified using a 4 mm mesh sieve and a 0.5 mm mesh sieve, A steam reforming catalyst composition (sample) was obtained, which was composed of “V · Ru-added nickel-based catalytically active particle powder in which silicon oxide and zirconium oxide are present on the surface” having a size of 0.5 mm to 4.0 mm.

Example 7
In Example 5, the mixing ratio of the aqueous precursor 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 further to zirconium acetate (molecular weight 327.4) 1.48 g . In the same manner as in Example 5 except this point, a steam reforming catalyst composition (sample) comprising "V-doped nickel-based catalyst active particle powder having silicon oxide and zirconium oxide present on the surface" was obtained.

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

(Gas reforming evaluation test)
5 g of the steam reforming catalyst composition (sample) obtained in each Example and Comparative Example was placed in a reformer, and the inside of the reformer was replaced with nitrogen gas. Next, the fuel reformer was heated in the electric furnace 8 to activate the catalyst, and when the catalyst temperature reached 500 ° C., the supply of city gas and water vapor was started to start the reduction activation process. The flow rate of the fuel gas at this time was set to be the space velocity (SV) 9000 h ^−1, and the ratio (S / C) of the city gas to the water vapor was set to be 2.5.
The temperature was further raised and held for 30 minutes when the catalyst temperature reached 550 ° C. Then, the temperature was raised again and heating was performed 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 amount of hydrogen generation was measured by a gas chromatograph (Fresh value).

After the Fresh value was measured as described above for the accelerated deterioration test of the catalyst performance, the S / C ratio was raised to 4.0 and the temperature was raised to 750 ° C. and maintained at 750 ° C. for 90 minutes. The hydrogen content was returned to an A / C ratio of 2.5, lowered to 550 ° C., and then 10 minutes elapsed (Aged value).

<Sintered 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) are measured, and the sintered density (g / cm ³ ) is determined. Calculated.

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

<Confirmation of existence of complex oxide phase of nickel vanadium>
The steam reforming catalyst composition (sample before gas evaluation test, referred to as "pre") obtained in the above examples and comparative examples, and after the above gas reforming evaluation test, that is, reduction activation treatment, measurement of hydrogen generation amount X-ray diffraction analyzer (Rigaku Co., Ltd.) for each of the steam reforming catalyst compositions (referred to as “Aged after”) collected by heating the samples that had undergone the accelerated deterioration test and the hydrogen generation amount to room temperature in a nitrogen atmosphere X-ray diffraction (XRD) measurement was carried out using RINT TTRIII)) (see FIGS. 3 to 6).
Then, was there a composite oxide phase of nickel vanadium belonging to the obtained X-ray diffraction pattern (from the figure, Ni ₃ (VO ₄ ) O ₂ , (V _1.34 Ni _0.66 ) O ₃ etc. In the table, the complex oxide phase of nickel vanadium is simply shown as "complex oxide", and evaluated as "yes" when the presence was confirmed and "none" when the presence was not confirmed. .

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

<Surface coverage>
The surface coverage (= following addition amount of surface treatment agent (g) x 100) can be calculated from the following two formulas.
Minimum covering area (m ² / g) = 6.02 x 10 ²³ x 13 x 10 ^-20 / surface treating agent molecular weight Surface treating agent added amount (g) = Ni (OH) ₂ weight (g) x Ni (OH) ₂ Specific surface area (m ² / g) / minimum coverage area (m ² / g)
Here, the surface treatment agent indicates the silane coupling agent and zirconium acetate used in the above examples.
In Examples 6 and 7 in which two types of surface treatment agents, a silane coupling agent and zirconium acetate, were used, the average molecular weight according to the molar ratio of the two 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 of the steam reforming catalyst compositions (samples) obtained in the above Example 1, Examples 2-1 to 2-2 and Examples 3 to 7 was used as an EDX of FE-SEM (manufactured by JSM-7001F / JEOL). It was confirmed that in any steam reforming catalyst composition, vanadium is present more on the surface than inside the catalytically active particles, and is not scattered on the surface of the catalytically active particles but on the surface. It could be confirmed that it exists in a dispersed state.
In addition, according to the above-described example and the test results that the inventor has conducted, as in Comparative Example 1, the nickel-based catalytically active particle powder to which vanadium is not added is sintered from the stage of reduction activation treatment at 550 ° C. It is confirmed that the catalyst activity is reduced because

The catalytically active particles (after Aged) after the above gas reforming evaluation test of the steam reforming catalyst composition obtained in the above Examples and Comparative Examples were observed with a scanning electron microscope (see FIGS. 7 to 15), About comparative example 1, it turned out that it metal-ized by the reducing atmosphere and it fuse | melted (FIG. 7).
On the other hand, in Example 1, the increase in particle diameter due to sintering is suppressed by the effect of adding vanadium (V) (FIG. 8), and in Example 2-1, sintering is suppressed and the grain boundaries are It was found that a gap was present (FIG. 9). In all of Examples 2-2 to 2-4, it was found that the grain growth was suppressed by the effect of the addition of V (FIGS. 10 to 12). In all of Examples 2-5 to 2-7, it was found that even when V was further added, the effect of suppressing the grain growth could be sustained and the deterioration of the catalyst performance could be prevented (FIGS. 13 to 15).

When the sample after the catalyst performance deterioration accelerated test of Comparative Example 1 was recovered, it was metallized in gray and was hard sintered, and it was difficult to grind in a mortar.
On the other hand, it was found that by adding vanadium, sintering can be suppressed not only at the time of the reductive activation treatment at 550 ° C. but also during the reforming reaction, and the decrease of the catalyst activity can be suppressed. In addition, each sample of the example after the catalyst performance deterioration accelerated test was black, and it was found that sintering was not progressing because it was easily ground in a mortar.

In addition, a portion of each of the steam reforming catalyst compositions (samples) obtained in Examples 3 to 7 was recovered, and distributed on the surface of the nickel particles by EDX of FE-SEM (manufactured by JSM-7001F / JEOL). It was confirmed that silicon and oxygen, or zirconium and oxygen, or silicon, zirconium and oxygen were uniformly distributed on the surface of the nickel particles, ie, catalytically active particles, without being ubiquitous.
Thus, the presence of a suitable amount of silicon oxide or zirconium oxide or both on the surface of the catalytically active particles further enhances sintering during the reduction treatment at 550 ° C. and further the reforming reaction. It has been found that this can be suppressed, and the reduction in catalyst activity can be further suppressed. In particular, it has been found that the catalyst performance is maintained after reduction and exposure to a high temperature environment of 550 ° C. or more for a long time, and thermal degradation can be suppressed. Such an effect is due to the presence of a suitable amount of silicon oxide or zirconium oxide or both on the surface of the catalytically active particles, in addition to the anchor effect that the surface oxide restricts the movement of the substance constituting the catalyst particles. Since the Ni component and the V component form a compound having a high specific surface area, it can be inferred that sintering is suppressed.

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

1 Gas fuel (city gas)
2 Gas mass flow controller 3 Pure water tank 4 Liquid mass flow controller 5 Electric furnace (fixed at 300 ° C)
6 vaporizer 7 fuel gas / steam mixing section 8 electric furnace 9 reforming catalyst 10 reforming catalyst temperature measurement thermocouple 11 bubbler 12 water remover 13 gas chromatograph

Claims

A steam reforming catalyst composition comprising catalytically active particles containing a steam reforming catalytically active component and vanadium.
The steam reforming catalyst composition according to claim 1, which contains vanadium in a ratio of 1 mol% or more 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 includes at least one element of Fe, Ni, Co, Ru, Rh, Pt, Pd, and Ir. Composition.
At least one element of Fe, Ni, Co, Ru, Rh, Pt, Pd and Ir is contained as a metal, an oxide or a mixture thereof or a solid solution thereof as the steam reforming catalyst active component. The steam reforming catalyst composition according to any one of claims 1 to 3, wherein
5. The steam reforming catalyst composition according to claim 1, 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 a silicon oxide or a zirconium oxide or both are present on the surface of the catalytically active particles.
A steam reforming catalyst formed by forming the steam reforming catalyst composition according to any one of claims 1 to 6 into pellets.
A steam reforming catalyst comprising a structure in which a steam reforming catalyst composition according to any one of claims 1 to 6 is supported on a substrate.