KR102462115B1 - Composition for water splitting material - Google Patents

Abstract

The present invention relates to a composition for a water decomposing material. In one embodiment, the composition for a water-decomposing material comprises: 100 parts by weight of a solid raw material including an iron oxide-based active material and a support of a spinel structure, 1 to 10 parts by weight of an anionic dispersant; and 1 to 10 parts by weight of an organic binder, wherein the organic binder includes a glycol-based binder, and the iron oxide-based active material has an average size of less than 17 μm and a needle-like specific surface area of 40 to 200 m ² /g. Contains ferric trioxide hydrate (Fe ₂ O ₃ ·H ₂ O), and the solid raw material includes 50 to 90% by weight of an iron oxide-based active material and 10 to 50% by weight of a support, and the support is magnesium aluminate (MgAl) ₂ O ₄ ).

Description

Composition for water decomposition material {COMPOSITION FOR WATER SPLITTING MATERIAL}

The present invention relates to a composition for a water decomposing material.

Hydrogen is currently in the spotlight as an eco-friendly energy fuel for revitalizing the low-carbon economy and reducing greenhouse gases. The conventional hydrogen production method uses a reforming reaction using hydrocarbon-based fossil fuels, but this method produces carbon dioxide (CO ₂ ), a greenhouse gas, together with hydrogen and discharges them to the atmosphere. Therefore, in order to increase the purity of hydrogen and reduce the emission of carbon dioxide (CO ₂ ), a separate additional process is required at the rear end of the reforming process.

As an alternative technology to solve this problem, there is a hydrogen production technology through a chemical looping water splitting (CLWS) reaction using a material made of metal oxide. In this technology, as a material made of metal oxide is reduced by a reducing gas, the material emits oxygen and becomes metal at the same time, and then the oxidation reaction with air (Air) or water (H ₂ O), which is an oxidizing gas containing oxygen atoms, is performed. is returned to the metal oxide. Depending on the type of reducing agent and oxidizing agent, this technology can be used for various purposes such as carbon dioxide (CO ₂ ) capture during combustion and hydrogen production.

On the other hand, when hydrogen (H ₂ ) or carbon monoxide (CO) is used as a reducing agent, metal oxide (MeO) becomes metal (Me) through a reduction reaction as shown in Formulas A-1 and A-2 below, and water (H ₂ O) Or carbon dioxide (CO ₂ ) is generated.

[Formula A-1]

Reduction reaction: MeO + H ₂ → Me + H ₂ O

[Formula A-2]

MeO + CO → Me + CO ₂

Therefore, carbon dioxide (CO ₂ ), which can be generated by the reduction reaction, can be captured with high purity of carbon dioxide (CO ₂ ) only by condensation of water (H ₂ O) without a separate gas separation process, and the reduced material is obtained by the following formula B-1 And as shown in Formula B-2, it reacts with oxygen atoms contained in water (H ₂ O) or air (Air) and is regenerated in the form of metal oxide (MeO) to return to its original form.

[Formula B-1]

Oxidation reaction: Me + H ₂ O → MeO + H ₂

[Formula B-2]

Me + O ₂ → 2MeO

At this time, since hydrogen can be generated only through an oxidation reaction with water (H ₂ O) as shown in Formula B-1, in a process where hydrogen production is the main purpose, the performance is performed in the oxidation reaction with water (H ₂ O) after reduction The development of this excellent metal oxide-based material is an important factor.

In particular, water decomposition materials using iron oxide are known to have excellent hydrogen production capacity due to their excellent reactivity with water. However, the water decomposition material using iron oxide undergoes a stepwise oxidation/reduction reaction as shown in Formula C below, and exists in the air in various forms such as ferric trioxide, triiron tetraoxide, and iron oxide hydrate. Therefore, it is important to optimize the composition of the water decomposition material by selecting the most suitable iron oxide to be used in hydrogen production technology.

[Formula C]

Fe ₂ O ₃ ↔ Fe ₃ O ₄ ↔ FeO ↔ Fe

Background art related to the present invention is disclosed in Japanese Patent Publication No. 6048951 (published on December 21, 2016, title of the invention: high active oxygen carrier material of chemical loop method).

One object of the present invention is to provide a water decomposition material that is excellent in thermal stability, durability and long-term performance, and can prevent performance degradation during repeated redox reactions at high temperatures.

Another object of the present invention is to provide a water decomposition material having excellent reactivity with water and hydrogen production efficiency.

Another object of the present invention is to provide a composition for the water decomposition material.

Another object of the present invention is to provide a method for manufacturing a water decomposing material using the composition for water decomposing material.

Another object of the present invention is to provide a chemical roofing type water decomposition method using the water decomposition material.

One aspect of the present invention relates to a water decomposition material. In one embodiment, the water-decomposing material includes an iron oxide-based active material and a support having a spinel structure, and the iron oxide-based active material has an average size of less than 17 μm.

In one embodiment, the water-decomposing material may include 50 to 90% by weight of an iron oxide-based active material and 10 to 50% by weight of the support.

In one embodiment, the iron oxide-based activator may include an iron oxide of Formula 1 below:

[Formula 1]

Fe _a O _b H _c

(In Formula 1, a is 2 or 3, b is 3 or 4, and c is 0 or 2).

In one embodiment, the iron oxide-based active material may be needle-shaped or spherical.

In one embodiment, the iron oxide-based active material may include needle-shaped ferric trioxide hydrate (Fe ₂ O ₃ ·H ₂ O) having a specific surface area of 40 m ² /g or more.

In one embodiment, the water decomposition material is a mixed gas (flow rate 100 l/min) containing hydrogen and nitrogen in a 1:9 volume ratio and a reduction reaction (950°C, 30 minutes), followed by water and nitrogen in a 1:9 volume ratio In an oxidation-reduction reaction in which one cycle of oxidation reaction (950°C, 20 minutes) with a mixed gas (flow rate 100 l/min) containing :

[Equation 1]

Oxidation amount (wt%) = [(W2-W1)/W1] * 100

(In Equation 1, W1 is the initial mass of the water-decomposing material, and W2 is the mass of the water-decomposing material measured after 20 cycles).

Another aspect of the present invention relates to the composition for the water decomposition material. In one embodiment, the composition for a water-decomposing material comprises: a solid raw material comprising an iron oxide-based active material and a support of a spinel structure; dispersant; and an organic binder, wherein the iron oxide-based active material has an average size of less than 17 μm.

In one embodiment, the composition for a water decomposition material includes 100 parts by weight of a solid raw material, 1 to 10 parts by weight of a dispersant, and 1 to 10 parts by weight of an organic binder, and the solid raw material is 50 to 90% by weight of an iron oxide-based active material and It may contain 10 to 50% by weight of the support.

In one embodiment, the iron oxide-based activator may include an iron oxide of Formula 1 below:

[Formula 1]

Fe _a O _b H _c

(In Formula 1, a is 2 or 3, b is 3 or 4, and c is 0 or 2).

In one embodiment, the dispersant may include an anionic dispersant, and the organic binder may include a glycol-based binder.

In one embodiment, 100 to 150 parts by weight of a solvent may be further included with respect to 100 parts by weight of the solid raw material.

Another aspect of the present invention relates to a method for manufacturing the water decomposition material. In one embodiment, the method for producing a water decomposition material comprises the steps of preparing a first mixture comprising a solid raw material; preparing a second mixture including the first mixture, a dispersant, and an organic binder; drying and filtering the second mixture to obtain a filtrate; and calcining the filtrate, wherein the solid raw material includes an iron oxide-based active material and a support having a spinel structure, and the iron oxide-based active material has an average size of less than 17 μm.

In one embodiment, the second mixture is prepared by adding a dispersing agent to the first mixture and stirring at 400 to 650 rpm; And adding an organic binder to the first agitated material, and the step of secondary stirring at 400 ~ 650rpm; can be prepared including.

In one embodiment, the drying is carried out at 120° C. or higher, and the filtrate may have a size of 50 to 150 μm.

In one embodiment, the sintering is carried out including the step of raising and maintaining the temperature of the filtrate from 200 ° C. to 100 ° C. at intervals of 3 to 8 ° C./min. can be

Another aspect of the present invention relates to a chemical roofing type water decomposition method using the water decomposition material. In one embodiment, the chemical roofing water decomposition method comprises the steps of reducing the water decomposition material by reacting the water decomposition material with hydrogen; and reacting the reduced water decomposing material with water to regenerate the water decomposing material.

The water decomposition material according to the present invention has excellent thermal stability, durability and long-term performance, and thus can prevent performance degradation during repeated redox reactions at high temperatures, and can have excellent reactivity with water and hydrogen production efficiency.

1 shows a method for manufacturing a water decomposition material according to an embodiment of the present invention.
2 is a scanning electron microscope (SEM) photograph of the water-decomposed material of Example 1.
3 is a scanning electron microscope (SEM) photograph of the water-decomposed material of Example 2.

In describing the present invention, if it is determined that a detailed description of a related known technology or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

And the terms described below are terms defined in consideration of functions in the present invention, which may vary depending on the intention or custom of the user or operator, so the definition should be made based on the content throughout this specification describing the present invention.

water decomposition material

One aspect of the present invention relates to a water decomposition material. In one embodiment, the water decomposition material is an iron oxide-based active material; and a support of a spinel structure.

The iron oxide-based activator directly participates in the chemical roofing type water decomposition reaction, and the chemical form may change during the water decomposition reaction process.

In one embodiment, the iron oxide-based active material has an average size of less than 17 μm. The average size may mean a “maximum length” or “diameter” of the iron oxide-based active material. When the iron oxide-based activator having the average size of 17 μm or more is applied, the reaction efficiency, durability, and long-term performance of the water-decomposing material at high temperatures may be reduced. For example, the iron oxide-based active material may have an average size greater than 0 and 16.5 μm. For another example, it may be 3 ~ 15㎛.

In one embodiment, the iron oxide-based activator may include an iron oxide of Formula 1 below:

[Formula 1]

Fe _a O _b H _c

(In Formula 1, a is 2 or 3, b is 3 or 4, and c is 0 or 2).

When iron oxide satisfying the condition of Formula 1 is included, oxygen transfer efficiency, durability, and long-term performance of the water decomposing material may be reduced.

In one embodiment, the iron oxide-based activator is Fe ₂ O ₃ (a=2, b=3, c=0) called ferric trioxide or red iron oxide; Fe ₂ O ₃ ·H ₂ O, also called ferric trioxide hydrate or yellow iron oxide (a=2, b=4, c=2); and Fe ₃ O ₄ (a=3, b=4, c=0), also called triferric tetraoxide or black iron oxide; It may include one or more of The iron oxide-based active material of the above type may have different colors at room temperature, and thus can be visually distinguished.

In one embodiment, the iron oxide-based active material may be needle-shaped or spherical. In the above form, the reactivity of the water-decomposing material may be excellent.

In one embodiment, the iron oxide-based active material may include needle-shaped ferric trioxide hydrate (Fe ₂ O ₃ ·H ₂ O) having a specific surface area of 40 m ² /g or more. When the needle-shaped ferric trioxide hydrate of the specific surface area condition is included, the surface area is higher than that of the spherical iron oxide-based active material, so that the contact area with the gaseous oxidizing agent and the reducing agent in the surface reaction step of the water decomposition reaction is increased. Reactivity is further improved, durability is excellent, and reactivity degradation is minimized even in repeated oxidation-reduction reactions at high temperatures, so that long-term reactivity can be excellent. For example, the specific surface area may be 40 to 200 m ² /g.

In another embodiment, the iron oxide-based active agent may include spherical ferric trioxide having a specific surface area of 7 m ² /g or more. Under the above conditions, the reactivity, durability and long-term reactivity of the water-decomposing material at high temperature may be excellent. The spherical ferric trioxide may have a specific surface area of 7 to 20 m ² /g.

The iron oxide-based activator may be included in an amount of 50 to 90% by weight based on the total weight of the water-decomposing material. When included under the above conditions, the reactivity, durability and long-term reactivity of the water-decomposing material at high temperatures may be excellent. For example, 65 to 75% by weight may be included.

The support of the spinel structure may include a porous structure that imparts strength and structural stability to the water-decomposing material, and allows the iron oxide-based active material to be uniformly dispersed. In one embodiment, the support of the spinel structure may include magnesium aluminate (MgAl ₂ O ₄ ). When the support is included, the iron oxide-based active material is easily dispersed, and the stability, strength and thermal stability of the water-decomposing material may be excellent.

In one embodiment, the support may be included in an amount of 10 to 50% by weight based on the total weight of the water-decomposing material. When included in the above range, the strength and thermal stability and long-term performance of the water-decomposing material may be excellent. For example, 25 to 35% by weight may be included.

In one embodiment, the water decomposition material is a mixed gas (flow rate 100 l/min) containing hydrogen (H ₂ ) and nitrogen (N ₂ ) in a volume ratio of 1:9 and a reduction reaction (950 ° C., 30 minutes), followed by water (or water vapor, H ₂ O) and nitrogen (N ₂ ) Oxidation-reduction reaction in which one cycle of oxidation reaction (950 ° C, 20 minutes) with a mixed gas (flow rate 100 l/min) containing nitrogen (N 2 ) in a volume ratio of 1:9 In , the oxidation amount after the 20th cycle oxidation reaction represented by the following formula 1 may be 16 wt% or more (16 g or more oxidation in 100 g of the water decomposition material):

[Equation 1]

Oxidation amount (wt%) = [(W2-W1)/W1] * 100

(In Equation 1, W1 is the initial mass of the water-decomposing material, and W2 is the mass of the water-decomposing material measured after 20 cycles).

In one embodiment, the amount of oxidation of the water decomposing material can be calculated as a percentage of the increase in the mass according to the oxidation reaction relative to the initial mass, as shown in Equation 1-1:

[Equation 1-1]

The oxidation amount according to Equation 1 may be measured using thermogravimetric analysis (TGA).

The long-term stability of the water-decomposing material of the present invention may be excellent under the oxidation amount condition of Equation 1 above. For example, the oxidation amount according to Equation 1 may be 16 to 20 wt%.

Composition for water decomposition material

Another aspect of the present invention relates to a composition for a water decomposing material for producing the water decomposing material. In one embodiment, the composition for a water-decomposing material comprises: a solid raw material comprising an iron oxide-based active material and a support of a spinel structure; dispersant; and an organic binder, wherein the iron oxide-based active material has an average size of less than 17 μm. For example, the iron oxide-based active material may have an average size greater than 0 and 16.5 μm. For another example, it may be 3 ~ 15㎛.

Since the solid raw material may be the same as that described above, a description thereof will be omitted.

The solid raw material may include 50 to 90% by weight of the iron oxide-based active material and 10 to 50% by weight of the support. When included under the above conditions, the reactivity, durability and long-term reactivity of the water-decomposing material at high temperatures may be excellent. For example, the solid raw material may include 65 to 75% by weight of the iron oxide-based active material and 25 to 35% by weight of the support.

The dispersant may include an anionic dispersant. When the dispersing agent is included, the dispersibility of the iron oxide-based active material and the mixing property of the composition are excellent, and thus the reaction efficiency may be excellent. For example, the anionic dispersant may include at least one of an ammonium polycarboxylic acid salt, a polycarboxylic acid sodium salt, and a polycarboxylic acid potassium salt.

In one embodiment, the dispersant may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the solid raw material. When included in the above range, the dispersibility of the iron oxide-based active material and the mixing property of the composition may be excellent. For example, 1 to 6 parts by weight may be included.

The organic binder may serve to provide mechanical strength of the water-decomposing material by easily bonding the solid raw material including the active material and the support to each other during the manufacturing process of the composition.

In one embodiment, the organic binder may include a glycol-based binder. When the glycol-based binder is included, the composition may have excellent mixing properties, and mechanical strength such as durability of the water-decomposable material may be excellent. For example, the glycol-based binder may include one or more of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol.

In one embodiment, the organic binder may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the solid raw material. When included in the above range, the dispersibility of the iron oxide-based active material and the mixing property of the composition may be excellent. For example, 1 to 6 parts by weight may be included.

In one embodiment, the composition for water decomposition material may further include a solvent. When the solvent is included, the mixability and dispersibility of the composition may be excellent.

In one embodiment, the solvent may include at least one of water, an aromatic hydrocarbon-based compound, an ether-based compound, and an alcohol-based compound. For example, it may include water.

In one embodiment, the aromatic hydrocarbon-based compound may include at least one of toluene, benzene, xylene, tetrahydrofuran (THF), and N-methyl-2-pyrrolidone (NMP).

In one embodiment, the ether-based compound is 3-methoxybutanol, methyl cellosolve (ethylene glycol monomethyl ether), ethylene glycol monoethyl ether (cellosolve), butyl cellosolve (ethylene glycol monobutyl ether), carr It may include at least one of bitol (diethylene glycol monoethyl ether), butyl carbitol (diethylene glycol monobutyl ether), and propylene glycol monomethyl ether.

In one embodiment, the alcohol-based compound may include at least one of ethanol, methanol, butanol, isobutanol, and isopropyl alcohol.

In one embodiment, the solvent may be included in an amount of 100 to 150 parts by weight based on 100 parts by weight of the solid raw material. When included under the above conditions, the active material of the solid raw material is easily dispersed on the surface of the support, the composition has excellent mixability and dispersibility, and the activation efficiency of the water-decomposing material can be increased.

The oxidation-reduction reaction for hydrogen production using iron oxide-based metal materials takes place at a high temperature of 800°C or higher. However, at a high temperature of 800° C. or higher, the aggregation phenomenon of iron (Fe)-based oxides is promoted, and the long-term performance and durability of the material deteriorate in the repeated oxidation-reduction reaction. Therefore, in order to increase hydrogen production and improve the efficiency of the reaction process, it is necessary to develop a water decomposition material using an iron oxide-based material that maintains excellent performance even in repeated oxidation-reduction reactions at high temperatures as an activator.

In the present invention, iron oxide-based (Fe _a O _b H _c /a = 2,3, b = 3,4, c = 0,2) material is applied as an activator, and a spinel structure with excellent physicochemical stability at high temperature Magnesium aluminate (MgAl ₂ O ₄ ) is applied as a support to have excellent reactivity with water (H ₂ O) during oxidation-reduction reactions that are repeatedly performed at a temperature of 900° C. or higher for 20 or more times, resulting in excellent oxygen transfer amount and thermal stability. As the reaction proceeds, it may be possible to produce an optimal composition and mass production of a material with insignificant degree of inactivation.

Water-decomposing material manufacturing method

Another aspect of the present invention relates to a method for manufacturing the water decomposition material.

1 shows a method for manufacturing a water decomposition material according to an embodiment of the present invention. Referring to FIG. 1 , the method for manufacturing a water decomposition material includes (S10) a first mixture preparation step; (S20) preparing a second mixture; (S30) obtaining a filtrate; and (S40) a firing step.

More specifically, the method for producing a water decomposition material comprises the steps of (S10) preparing a first mixture containing a solid raw material; (S20) preparing a second mixture including the first mixture, a dispersant, and an organic binder; (S30) drying and filtering the second mixture to obtain a filtrate; and (S40) calcining the filtrate.

(S10) first mixture preparation step

The step is a step of preparing a first mixture containing the solid raw material. For example, the first mixture may prepare a first mixture containing a solid raw material including an iron oxide-based active material and a support having a spinel structure, and a solvent.

The iron oxide-based activator, the support, and the solvent may be the same as those described above.

The solid raw material includes an iron oxide-based active material and a support having a spinel structure, and the iron oxide-based active material has an average size of less than 17 μm. When the iron oxide-based activator having the average size of 17 μm or more is applied, the reaction efficiency, durability, and long-term performance of the water-decomposing material at high temperatures may be reduced.

In one embodiment, the solvent may be included in an amount of 100 to 150 parts by weight based on 100 parts by weight of the solid raw material. When included under the above conditions, the active material of the solid raw material is easily dispersed on the surface of the support, and the mixability and dispersibility of the first mixture are excellent, and the activation efficiency of the water-decomposing material can be increased.

(S20) second mixture preparation step

The step is a step of preparing a second mixture including the first mixture, the dispersant and the organic binder.

The dispersant and the organic binder may be the same as those described above.

In one embodiment, the dispersant may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the solid raw material. When included in the above range, the dispersibility of the iron oxide-based active material and the mixing property of the composition may be excellent. For example, 1 to 6 parts by weight may be included.

In one embodiment, the organic binder may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the solid raw material. When included in the above range, the dispersibility of the iron oxide-based active material and the mixing property of the composition may be excellent. For example, 1 to 6 parts by weight may be included.

In one embodiment, the second mixture is prepared by adding a dispersant of the above-described content to the first mixture and stirring at 400 to 650 rpm to prepare a first stirring; And adding the organic binder of the above-described content to the first stirring material, and the step of secondary stirring at 400 ~ 650rpm; can be prepared including. Under the above conditions, the mixability and dispersibility are excellent during the first stirring and the second stirring, so that the durability and mechanical properties of the water decomposition material are excellent, and the hydrogen production efficiency and long-term reactivity can be excellent.

(S30) step of obtaining the filtrate

The step is a step of drying and filtering the second mixture to obtain a filtrate. In one embodiment, the drying may be carried out by drying the second mixture at 120° C. or higher. Under the above conditions, the moisture of the second mixture is easily evaporated, and the durability and mechanical properties of the water-decomposing material are excellent, and long-term reactivity may be excellent. For example, it can be dried at 120 ~ 200 ℃ for 10 ~ 30 hours.

In one embodiment, the filtration may be carried out through a sieve or the like. In one embodiment, the filtrate may have a size of 50 to 150 μm. The reaction efficiency of the present invention may be excellent under the above conditions. For example, the filtrate may have a size of 53 to 150 μm.

(S40) firing step

The step is a step of calcining the filtrate. In one embodiment, the firing may be carried out at 800 to 1200 °C. Under the above conditions, the mechanical strength of the water-decomposing material may be excellent, and the reaction efficiency may be excellent.

In one embodiment, the calcination, but raising and maintaining the temperature of the filtrate at a temperature increase rate of 3 ~ 8 ℃ / min step by step at intervals of 100 ℃ from 200 ℃ to 800 ~ 1200 ℃, it may include the step of maintaining the temperature rise to 800 ~ 1200 ℃ have. Under the above conditions, the mechanical strength of the water-decomposing material may be excellent, and the reaction efficiency may be excellent.

For example, the calcination is carried out by raising and maintaining the temperature of the filtrate at a temperature increase rate of 5 to 8 °C/min step by step at intervals of 100 °C from 200 °C, raising the temperature to 800 to 1200 °C and maintaining it for 10 to 20 hours. can When calcined under the above conditions, the mechanical strength of the water decomposition material may be excellent, and hydrogen production efficiency and reaction efficiency may be excellent.

Chemical roofing type water decomposition method using water decomposition material

Another aspect of the present invention relates to a chemical roofing type water decomposition method using the water decomposition material. In one embodiment, the chemical roofing water decomposition method comprises the steps of reducing the water decomposition material by reacting the water decomposition material with hydrogen; and reacting the reduced water decomposing material with water to regenerate the water decomposing material.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, these are presented as preferred examples of the present invention and cannot be construed as limiting the present invention in any sense. Content not described here will be omitted because it can be technically inferred sufficiently by those skilled in the art.

Examples and Comparative Examples

Example 1

(1) Preparation of the first mixture: 70 wt% of ferric trioxide (Fe ₂ O ₃ ) and a spinel structure support (magnesium aluminate (MgAl ₂ O ₄ )) 30 wt. % was mixed with 100 parts by weight of a solid raw material containing 100 to 150 parts by weight of a solvent (distilled water) to prepare a first mixture.

(2) Preparation of the second mixture: 2 parts by weight of a dispersant (ammonium polycarboxylic acid salt) was added to the first mixture based on 100 parts by weight of the solid raw material, and stirred at 400 to 650 rpm to prepare a first stirred product. Then, 3 parts by weight of an organic binder (polyethylene glycol) was added to the first stirred water based on 100 parts by weight of the solid raw material, and stirred at 400 to 650 rpm to prepare a second mixture.

(3) Obtaining filtrate: The second mixture was dried in an air atmosphere reflux dryer at 120 to 200° C. for 24 hours, and filtered through a sieve to obtain a filtrate having a size of 53 to 150 μm.

(4) Firing: The filtrate was heated and maintained at a temperature increase rate of 5 °C/min step by step at intervals of 100 °C from 200 °C, but the temperature was raised to 1000 °C and held for 12 hours and calcined to prepare a water decomposition material.

Example 2

A water decomposition material was prepared in the same manner as in Example 1, except that ferric trioxide hydrate (Fe ₂ O ₃ ·H ₂ O) was applied as the iron oxide-based activator.

Example 3

A water decomposition material was prepared in the same manner as in Example 1, except that triiron tetraoxide (Fe ₃ O ₄ ) of the conditions in Table 1 below was applied as the iron oxide-based activator.

Comparative Examples 1 to 6

A water-decomposing material was prepared in the same manner as in Example 1, except that the iron oxide-based activator or support having the conditions in Table 2 below was applied.

Experimental example

Long-term reaction performance evaluation: For the water decomposition materials prepared in Examples 1 to 3 and Comparative Examples 1 to 6, long-term reaction performance was evaluated. Specifically, with respect to the water decomposition material (initial mass: 10 mg), a mixed gas (flow rate 100 l/min) containing hydrogen (H ₂ ) and nitrogen (N ₂ ) in a 1:9 volume ratio and a reduction reaction (950 ° C., 30 minutes), followed by an oxidation reaction (950°C, 20 minutes) with a mixed gas (flow rate 100 l/min) containing water (or water vapor, H ₂ O) and nitrogen (N ₂ ) in a 1:9 volume ratio 1 The oxidation-reduction reaction cycle was repeated, and the oxidation amount after the 5th cycle and the 20th cycle represented by the following formula 1 was measured using thermogravimetric analysis, and the results are shown in Table 3. In addition, at the end of the oxidation-reduction reaction of each cycle, pure nitrogen gas was flowed for 5 to 10 minutes to remove residual gas that may exist in the water decomposition material and the reaction device.

[Equation 1]

Oxidation amount (wt%) = [(W2-W1)/W1] * 100

(In Equation 1, W1 is the initial mass (mg) of the water-decomposing material, and W2 is the mass (mg) of the water-decomposing material measured after 5 cycles and 20 cycles).

2 is a scanning electron microscope (SEM) photograph of the water-decomposed material of Example 1 to which spherical ferric trioxide is applied, and FIG. 3 is a scanning electron microscope (SEM) of the water-decomposed material of Example 2 to which needle-shaped ferric trioxide hydrate is applied It's a photo. 2 and 3, in Examples 1 and 2, it can be confirmed that the iron oxide-based active material having an average particle size of less than 17 μm is homogeneously dispersed on the surface of the magnesium aluminate support having a spinel structure to form a water decomposition material. .

Referring to the results of Table 3, the water decomposition materials of Examples 1 to 3 are Comparative Examples 2, 4 and 6 to which alumina (Al ₂ O ₃ ), which is generally widely used as a support for chemical reaction materials such as catalysts and adsorbents, is applied. It was found that the measured oxidation amount after 5 cycles and 20 cycles improved performance by at least 6 wt % and at most 11 wt %.

In addition, in Examples 1 to 3, compared to Comparative Examples 1, 3 and 5 to which an iron oxide-based activator having an average particle size of 17 µm or more was applied, the oxidation amount measured after 5 cycles and 20 cycles was at least 0.5% by weight and at most 4% by weight. It was found that the performance improved.

Therefore, by preparing a water-decomposing material within the composition range presented in the present invention using an iron oxide-based active material having an average particle size of less than 17 μm and a spinel structure magnesium aluminate (MgAl ₂ O ₄ ) as a support, 900 It was confirmed that the oxygen delivery amount and long-term stability of the water decomposition material were improved at a high temperature of ℃ or higher.

Up to now, the present invention has been mainly examined in the examples. Those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (1)

100 parts by weight of a solid raw material comprising an iron oxide-based active material and a support having a spinel structure;
1-10 parts by weight of anionic dispersant; and
1 to 10 parts by weight of an organic binder;
The organic binder includes a glycol-based binder,
_The iron oxide _- based active material has an average size of less than 17 μm and a specific surface area of 40 to ₂₀₀ m ² /g.
The solid raw material contains 50 to 90% by weight of an iron oxide-based active material and 10 to 50% by weight of a support,
The support is magnesium aluminate (MgAl ₂ O ₄ ) A composition for a water-decomposing material, characterized in that it comprises.

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