KR102673713B1 - High-efficiency catalyst for hydrogen production through direct decomposition of methane and its preparation method - Google Patents

Abstract

The present invention relates to a highly efficient catalyst for hydrogen production through direct decomposition of methane and a method for producing the same. According to the present invention, in the method for producing a highly efficient catalyst for hydrogen production through direct decomposition of methane, nitrification is performed in high temperature water. A mixing step of preparing a mixture by dissolving molybdenum nitride (MoN) and a foaming agent; A primary stirring step of adding magnesium nitrate (MgN) to the mixture and stirring to prepare a primary stirred product; A secondary stirring step of preparing a secondary stirred product by adding a precursor solution to the first stirred product and stirring it; A highly efficient catalyst production method can be provided, including a reaction step of burning the secondary stirred material to obtain a reaction product and a pulverization step of pulverizing the reaction product.

Description

High-efficiency catalyst for hydrogen production through direct decomposition of methane and its preparation method}

The present invention relates to a highly efficient catalyst for hydrogen production through direct decomposition of methane and a method for producing the same. More specifically, by manufacturing a catalyst capable of direct decomposition of methane, it not only enables environmentally friendly hydrogen production without carbon dioxide emissions, but also enables environmentally friendly hydrogen production without carbon dioxide emissions. It relates to a highly efficient catalyst for hydrogen production through direct decomposition of methane, which has excellent hydrogen production efficiency, and a method for producing the same.

As global warming and climate change accelerate, interest in electricity production using renewable energy is increasing.

As technology for utilizing hydrogen energy among renewable energy sources receives attention, the issue of hydrogen production is also receiving attention.

Hydrogen can be classified according to the hydrogen production method and degree of eco-friendliness: gray hydrogen produced through fossil fuel reforming, blue hydrogen produced through fossil fuel reforming and carbon dioxide capture simultaneously, and water electrolysis produced through water decomposition. There is green hydrogen, etc.

Currently, about 70% of the hydrogen produced around the world is gray hydrogen through fossil fuel reforming. However, gray hydrogen produced through fossil fuel reforming has the problem of carbon dioxide emissions.

Accordingly, there is a trend to expand hydrogen production methods to eco-friendly hydrogen production methods such as blue hydrogen and green hydrogen.

Meanwhile, the existing production method through water gas reforming of natural gas has the disadvantage of generating carbon dioxide emissions as shown in equations (1) and (2) below, and ultimately results in the emission of 10 kg of carbon dioxide per 1 kg of hydrogen produced. .

Equation (1) CH ₄ + H ₂ O → CO + 3H ₂

Equation (2) CO + H ₂ O → CO ₂ + H ₂

On the other hand, in the case of a production method through direct decomposition of methane gas, carbon dioxide is not emitted as shown in equation (3) below.

Equation (3) CH ₄ → C(s) + 2H ₂

Therefore, there is a need to develop a hydrogen production method that does not generate carbon dioxide emissions.

Korean Patent No. 10-0899914 Steam reforming fuel processing device including methanol steam reforming catalyst, and method for generating hydrogen gas by steam reforming methanol (May 21, 2009)

In order to solve the above problems, the present invention manufactures a catalyst capable of direct decomposition of methane, which not only enables environmentally friendly hydrogen production without carbon dioxide emissions, but also enables hydrogen production through direct decomposition of methane with excellent hydrogen production efficiency. The purpose is to provide a highly efficient catalyst and a method for producing the same.

In order to solve the above problems, the method for producing a highly efficient catalyst for hydrogen production through direct decomposition of methane according to an embodiment of the present invention dissolves molybdenum nitride (MoN) and a foaming agent in high temperature water. A mixing step of preparing a mixture; A primary stirring step of adding magnesium nitrate (MgN) to the mixture and stirring to prepare a primary stirred product; A secondary stirring step of preparing a secondary stirred product by adding a precursor solution to the first stirred product and stirring it; A highly efficient catalyst production method can be provided, including a reaction step of burning the secondary stirred material to obtain a reaction product and a pulverization step of pulverizing the reaction product.

In addition, the mixing step is characterized by adding and dissolving 2 to 6 parts by weight of molybdenum nitride (MoN) and 12 to 30 parts by weight of a foaming agent in 40 to 60 parts by weight of water.

In addition, the foaming agent includes urea, glycine, sucrose, glucose, citric acid, carbohydrazide, oxalyldihydrazide, and hexamethylene. It is characterized by being one or more of tetramine (hexamethylenetetramine), hexamethylenediamine, and acetylacetone.

Additionally, the first stirring step is characterized by adding 40 to 60 parts by weight of magnesium nitrate (MgN) to the mixture.

In addition, the primary stirring step is characterized in that the molar ratio (Mo/Mg) of molybdenum (Mo) and magnesium (Mg) is 1 to 10 as the primary stirred product is prepared.

In addition, the precursor solution is characterized in that it is prepared by dissolving 0.5 to 4 parts by weight of the precursor in 20 to 30 parts by weight of water.

In addition, the precursors include FeS (iron sulfide), FeN (iron nitrate), FeCl ₂ (iron(Ⅱ) chloride), FeCl ₃ (iron(Ⅲ) chloride), CoS (cobalt sulfide), CoA (cobalt acetate), CoN It is characterized in that it is one or more of (cobalt nitrate), NiS (nickel sulfide), NiCl ₂ (nickel chloride), and NiN (nickel nitrate).

Additionally, the reaction step is characterized by subjecting the secondary stirred material to a combustion reaction at 400 to 800°C.

In addition, a highly efficient catalyst manufactured through a method for producing a highly efficient catalyst for hydrogen production through direct decomposition of methane according to an embodiment of the present invention can be provided.

Here, the high-efficiency catalyst is characterized by reacting at 700 to 1000°C when decomposing methane.

The high-efficiency catalyst for hydrogen production through direct decomposition of methane and its manufacturing method according to the embodiment of the present invention as described above enable the production of hydrogen through a direct decomposition reaction of methane, thereby enabling environmentally friendly hydrogen production without carbon dioxide emissions. You can.

In addition, the hydrogen production efficiency per mass is improved compared to existing thermal decomposition catalysts, resulting in high efficiency.

In addition, it can be manufactured at a relatively low cost compared to the previously reported catalyst manufacturing cost, so price competitiveness can be excellent.

Additionally, economic effects can be expected through the use of additionally obtained carbon materials.

1 is a flow chart schematically showing a method for producing a highly efficient catalyst for hydrogen production through direct decomposition of methane according to an embodiment of the present invention.
Figure 2 is a photograph of a highly efficient catalyst manufactured through the manufacturing method of Figure 1.
Figure 3 is a graph of methane gas conversion rate measurement results according to the molar ratio (Mo/Mg) of the high-efficiency catalyst and reaction temperature.
Figure 4 is an SEM photo analyzing the carbon material obtained through methane decomposition using a high-efficiency catalyst.
Figure 5 is a graph showing the results of measuring the strength of a carbon material obtained through methane decomposition using a high-efficiency catalyst.

Since the present invention can be subject to various changes and have various forms, specific embodiments will be described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the existence of a combination of features, numbers, steps, components, etc. described in the specification, but are not limited to one or more other features or numbers, It should be understood that the existence or addition possibility of combinations of steps, components, etc. is not excluded in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings they have in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

Here, repeated descriptions, known functions that may unnecessarily obscure the gist of the present invention, and detailed descriptions of configurations are omitted. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

The present invention relates to a highly efficient catalyst for hydrogen production through direct decomposition of methane and a method for producing the same. By manufacturing a thermal catalyst that can produce hydrogen by directly decomposing methane and applying it to hydrogen production, it is eco-friendly and does not emit carbon dioxide. The goal is to enable efficient hydrogen production and improve hydrogen production efficiency to ensure high efficiency.

In other words, the goal is to secure hydrogen production technology through a catalyst that can directly decompose methane, thereby replacing existing hydrogen production technology that involves carbon dioxide emissions.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

Figure 1 is a flowchart schematically showing a method for manufacturing a high-efficiency catalyst for hydrogen production through direct decomposition of methane according to an embodiment of the present invention, and Figure 2 is a photograph of the high-efficiency catalyst manufactured through the manufacturing method of Figure 1.

Referring to Figure 1, the method for producing a high-efficiency catalyst for hydrogen production through direct decomposition of methane according to an embodiment of the present invention includes a mixing step (S100), a first stirring step (S200), a second stirring step (S300), and reaction. It may include a step (S400) and a grinding step (S500).

The mixing step (S100) is a step of preparing a mixture by dissolving molybdenum nitride (MoN) and a foaming agent in high temperature water. 2 to 6 parts by weight of molybdenum nitride (MoN) is added to 40 to 60 parts by weight of water. It can be dissolved by adding 12 to 30 parts by weight of foaming agent.

Here, the high-temperature water may be water of 80 to 100° C. to facilitate dissolution of molybdenum nitride (MoN) and the foaming agent, but is not limited thereto.

In addition, if the water is less than 40 parts by weight, molybdenum nitride (MoN), foaming agent, etc. may not be dissolved, and if it is more than 60 parts by weight, combustion reaction efficiency may decrease and problems may occur in the production of reaction products.

Molybdenum nitride (MoN) helps the catalyst to be evenly dispersed without agglomerating, and ammonium molybdate tetrahydrate may be used, but is not limited to this.

In addition, molybdenum nitride (MoN) can be mixed in an amount of 2 to 6 parts by weight. If it is less than 2 parts by weight, the effect of preventing catalyst agglomeration is insufficient and pore characteristics may decrease, which may reduce catalyst efficiency. If it is more than 6 parts by weight, the pore characteristics may be reduced. In this case, durability, dimensional stability, etc. may be reduced.

The foaming agent first stirring step (S200) promotes the formation of foam when magnesium nitrate (MgN) is added and stirred later, and can reduce surface tension by expanding the surface area.

These foaming agents include urea, glycine, sucrose, glucose, citric acid, carbohydrazide, oxalyldihydrazide, and hexamethylenetetramine. It may be one or more of hexamethylenetetramine, hexamethylenediamine, and acetylacetone, of which citric acid is preferably used, but is not limited thereto.

In addition, the foaming agent can be mixed in an amount of 12 to 30 parts by weight. If it is less than 12 parts by weight, the function of the foaming agent may be insufficient, and if it is more than 30 parts by weight, the gas decomposition rate of the catalyst may be reduced.

This is set in consideration of the weight of magnesium nitrate (MgN) to be added later, and it may be desirable to add about 30 to 50% by weight relative to the weight of magnesium nitrate (MgN), so it is set accordingly.

Step S100 may be performed by adding molybdenum nitride (MoN) to high temperature water to completely dissolve it, and then adding a foaming agent to completely dissolve it, but is not limited to this.

The first stirring step (S200) is a step of adding magnesium nitrate (MgN) to the mixture prepared in step S100. 40 to 60 parts by weight of magnesium nitrate (MgN) is added to the mixture and stirred to form the first stirred product. It can be manufactured.

At this time, if magnesium nitrate (MgN) is less than 40 parts by weight, the methane decomposition efficiency of the catalyst may be reduced due to the small mass of Mg compared to Mo, and if it is more than 60 parts by weight, oxidation does not occur sufficiently and agglomeration occurs, resulting in poor pore characteristics. This may deteriorate.

In step S200, the primary stirred product is prepared by adding magnesium nitrate to the mixture, so that the molar ratio (Mo/Mg) of molybdenum (Mo) and magnesium (Mg) of the primary stirred product, that is, the high-efficiency catalyst, is 1 to 10. This can be done.

The efficiency of a high-efficiency catalyst, that is, the methane decomposition efficiency and the reaction temperature of the catalyst, may vary depending on the molar ratio (Mo/Mg). If the molar ratio (Mo/Mg) is outside the above range, the efficiency of the catalyst may decrease. , it may be desirable for the molar ratio (Mo/Mg) to be within the above range.

Additionally, in step S200, the reaction temperature of the catalyst can be controlled by adjusting the molar ratio (Mo/Mg).

At this time, it may be preferable that the mass (mol) of magnesium (Mg) is maintained at 0.02 mol and the mass (mol) of molybdenum (Mo) is changed to adjust the molar ratio (Mo/Mg), but it is not limited to this. , the mol number can also be changed in various ways.

For example, the mass (mol) of magnesium (Mg) is 0.02 mol, and if you want to adjust the molar ratio (Mo/Mg) from 1 to 10, the mass (mol) of molybdenum (Mo) is 0.02 mol, respectively. It can be 0.04mol, 0.06mol, 0.08mol, 0.10mol, 0.12mol, 0.14mol, 0.16mol, 0.18mol, 0.20mol.

The secondary stirring step (S300) is a step of preparing a secondary stirring product by adding a precursor solution to the primary stirring product prepared in step S200 and stirring. A precursor solution may be prepared and added to the primary stirring product.

First, in step S300, a precursor solution can be prepared by dissolving 0.5 to 4 parts by weight of the precursor in 20 to 30 parts by weight of high temperature water.

Here, the water may be heated to a high temperature of 80 to 100°C to facilitate better dissolution of the precursor, but is not limited thereto.

At this time, if the water is less than 20 parts by weight, the precursor may not be dissolved, and if it is more than 30 parts by weight, the reaction efficiency during the combustion reaction may decrease and problems may occur in the production of reaction products.

In addition, if the precursor is less than 0.5 parts by weight, pore characteristics may be reduced, and if it is more than 4 parts by weight, oxidation may not occur to a certain level and pore characteristics may be reduced.

Meanwhile, the precursors include FeS (iron sulfide), FeN (iron nitrate), FeCl ₂ (iron (Ⅱ) chloride), FeCl ₃ (iron (Ⅲ) chloride), CoS (cobalt sulfide), CoA (cobalt acetate), CoN ( It may be one or more of cobalt nitrate), NiS (nickel sulfide), NiCl ₂ (nickel chloride), and NiN (nickel nitrate), and iron nitrate (FeN) may be preferred, but is not limited thereto.

Additionally, the precursor may be used in hydrate form, but is not limited thereto.

More specifically, taking the case where the precursor is FeN (iron nitrate) as an example, as it is added to the primary stirred material and stirred, the molar ratio of molybdenum (Mo) and iron (Fe) (Mo/Fe) is 1 to 1. A precursor solution may be prepared to have 10.

In step S300, the precursor solution prepared in this way can be added to the first stirred water and stirred to prepare a second stirred product.

The reaction step (S400) is a step of obtaining a reaction product by burning the secondary agitated material prepared in step S300. The combustion reaction can be performed by putting the secondary agitated material in a box furnace and applying heat with or without the lid closed. there is.

More specifically, step S400 can cause a combustion reaction by applying heat to the secondary stirred material at 400 to 800°C, with 550°C being more preferable, but not limited thereto.

If the combustion reaction temperature in the S400 step is less than 400℃, problems may occur in catalyst production because dissolution does not occur due to the nano effect through nano-size of iron particles, and if it exceeds 800℃, the physical properties of the manufactured catalyst may deteriorate. You can.

Through step S400, a reaction product as shown in FIG. 2 can be produced. If the reaction is carried out without closing the lid of the box furnace, a reaction product like the one on the left may be produced, and if the reaction is carried out with the lid closed, a reaction product like the one on the right may be produced.

Here, depending on opening and closing the lid of the box furnace, the degree of iron oxidation may vary, and thus the gas decomposition rate of the high-efficiency catalyst may vary.

Additionally, the density of the reaction product produced may appear different; when manufactured with the lid closed, the density may appear higher than when manufactured without the lid closed.

In this S400 step, the reaction product may be generated by swelling. As the reaction product swells, the catalyst may be smoothly dispersed, and thus the pore characteristics may be improved.

The pulverizing step (S500) is a step of pulverizing the reaction product produced in step S400. The reaction product generated in the box furnace can be recovered and pulverized through a mixer. The particle size and apparent density of the catalyst vary depending on the pulverizing time. Because of this, grinding time can be said to be important.

Here, it may be desirable for the pulverization time to be 8 to 10 seconds. If it is less than 8 seconds, the area in which the catalyst is in contact with methane gas may be small, and if it is more than 10 seconds, the apparent density of the catalyst may be too low and methane decomposition efficiency may be reduced. You can.

It is possible to provide a high-efficiency catalyst manufactured through the method for producing a high-efficiency catalyst for hydrogen production through direct decomposition of methane according to the embodiment of the present invention as described above.

The highly efficient catalyst for hydrogen production through direct decomposition of methane according to an embodiment of the present invention prepared by the above method can perform methane decomposition by reacting at 700 to 1000 ° C. when decomposing methane. Here, a high-efficiency catalyst can have a methane decomposition rate of up to 84%.

Meanwhile, a high-efficiency catalyst can form carbon materials as it decomposes methane. Since the carbon materials formed here are materials such as carbon black and CNT, they can be utilized to obtain additional value.

As described above, the highly efficient catalyst for hydrogen production through direct decomposition of methane according to an embodiment of the present invention and its manufacturing method enable the production of hydrogen through a direct decomposition reaction of methane, thereby enabling eco-friendly hydrogen production without carbon dioxide emissions. It can be made possible.

In addition, the hydrogen production efficiency per mass is improved compared to existing thermal decomposition catalysts, resulting in high efficiency.

In addition, it can be manufactured at a relatively low cost compared to the previously reported catalyst manufacturing cost, so price competitiveness can be excellent.

Additionally, economic effects can be expected through the use of additionally obtained carbon materials.

Hereinafter, the present invention will be described in more detail through examples.

However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.

In addition, the embodiments of the present invention described below can be implemented with various substitutions, modifications, and changes without departing from the technical spirit of the present invention, and these implementations are within the scope of the technical field to which the present invention belongs from the description of the embodiments described above. Any expert can easily implement it.

[Experimental Example 1] Evaluation of methane decomposition rate according to catalyst molar ratio and reaction temperature

In order to confirm the methane decomposition efficiency according to the Mo/Mg molar ratio and reaction temperature of the high-efficiency catalyst of the present invention, methane gas conversion rate was measured by varying the catalyst molar ratio (Mo/Mg) and reaction temperature. Catalysts were prepared by varying the molar ratio (Mo/Mg) from 1 to 10 at intervals of 1, and the reaction was performed at different reaction temperatures of 800, 850, 900, and 950°C.

The results are as shown in Figure 3.

Figure 3 is a graph of methane gas conversion rate measurement results according to the molar ratio (Mo/Mg) of the high-efficiency catalyst and reaction temperature.

As can be seen in Figure 3, it was confirmed that different methane gas conversion rates appeared at the reaction temperature as the molar ratio of Mo/Mg of the catalyst changed.

In addition, it was confirmed that the methane gas conversion rate was particularly excellent when the Mo/Mg molar ratio of the catalyst was 5 and the reaction temperature was 900°C and when the Mo/Mg molar ratio was 8 and the reaction temperature was 950°C.

[Experimental Example 2] Evaluation of carbon materials obtained by catalytic methane decomposition

In order to confirm the carbon material formed during methane decomposition by the high-efficiency catalyst of the present invention, an experiment was conducted as follows.

A highly efficient catalyst was prepared so that the Mo/Mg molar ratio was 5, and methane decomposition was performed at 900°C with the prepared catalyst to produce hydrogen. At this time, a fixed bed horizontal reactor was used. The carbon material produced here was obtained, observed with an SEM, and its strength was measured.

The results are as shown in Figures 4 and 5.

Figure 4 is an SEM photograph analyzing the carbon material obtained through methane decomposition using a high-efficiency catalyst, and Figure 5 is a graph showing the results of measuring the strength of the carbon material obtained through methane decomposition using a high-efficiency catalyst. Meanwhile, in the result graph of FIG. 5, 1, 2, and 3 are the results of analyzing different points in the same high-efficiency catalyst.

As can be seen in Figures 4 and 5, it was confirmed that the carbon material obtained through methane decomposition using a high-efficiency catalyst was the same material as CNT.

Above, specific parts of the content of the present invention have been described in detail, and for those skilled in the art, it is clear that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. It will be obvious. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (8)

In the method of producing a highly efficient catalyst for hydrogen production through direct decomposition of methane,
A mixing step (S100) of preparing a mixture by dissolving molybdenum nitride (MoN) and a foaming agent in high temperature water;
A primary stirring step (S200) of adding magnesium nitrate (MgN) to the mixture and stirring to prepare a primary stirred product;
A secondary stirring step (S300) of adding a precursor solution to the first stirring and stirring to prepare a secondary stirrer;
A reaction step (S400) of obtaining a reaction product by burning the secondary stirred material; and
A high-efficiency catalyst production method comprising a pulverizing step (S500) of pulverizing the reaction product,
In the mixing step (S100), the foaming agent is citric acid,
In the first stirring step (S200), the addition of magnesium nitrate (MgN) produces a stirred product, so that the molar ratio (Mo/Mg) of molybdenum (Mo) and magnesium (Mg) is 1 to 10. Let this happen,
In the second stirring step (S300), the precursor solution is a solution containing iron nitrate (FeN), which is added so that the molar ratio (Mo/Fe) of molybdenum (Mo) and iron (Fe) is 1 to 10. A method for producing a high-efficiency catalyst, characterized in that.
According to paragraph 1,
The mixing step is,
A method for producing a highly efficient catalyst, characterized in that 2 to 6 parts by weight of molybdenum nitride (MoN) and 12 to 30 parts by weight of a foaming agent are added and dissolved in 40 to 60 parts by weight of water.
According to paragraph 2,
The first stirring step is,
A method for producing a highly efficient catalyst, characterized in that 40 to 60 parts by weight of magnesium nitrate (MgN) is added to the mixture.
delete According to paragraph 1,
The precursor solution is,
A method for producing a highly efficient catalyst, characterized in that it is prepared by dissolving 0.5 to 4 parts by weight of the precursor in 20 to 30 parts by weight of water.
According to paragraph 1,
The reaction step is,
A method for producing a highly efficient catalyst, characterized in that the secondary stirred product is subjected to a combustion reaction at 400 to 800 ° C.
A highly efficient catalyst manufactured through the production method of any one of claims 1, 2, 3, 5, and 6.
In clause 7,
A highly efficient catalyst characterized in that it reacts at 700 to 1000°C when decomposing methane.