KR102594504B1 - A nitride catalysts for synthesize ammonia at low temperature and low temperature ammonia synthesis from water and air by using nitride catalysts - Google Patents

Abstract

The catalyst according to the present invention synthesizes a large amount of ammonia at a much lower temperature or under lower energy than the existing Haber-Bosch process or electrochemical synthesis method by containing a metal compound containing a transition metal as a main component. This is possible, and at the same time, it has the advantage of being able to synthesize environmentally friendly ammonia that does not produce impurities such as carbon dioxide using water and air.
In addition, it consumes much less energy than the electrical synthesis method, and because it does not use electrodes, there is no risk of corrosion and the creation of additional impurities can be suppressed.

Description

Nitride catalyst for low temperature synthesis of ammonia and low temperature synthesis method of ammonia from water and air using the same {A nitride catalysts for synthesize ammonia at low temperature and low temperature ammonia synthesis from water and air by using nitride catalysts}

The present invention relates to a low-temperature synthesis method of ammonia from water and air using a nitride catalyst, and specifically, by using a metal nitride compound containing a transition metal as a catalyst, compared to the existing Haber-Bosch process. It relates to a low-temperature synthesis method of ammonia from water and air using a nitride catalyst, which enables large-scale ammonia synthesis even at much lower temperatures and pressures and enables eco-friendly ammonia synthesis using only water and air.

Ammonia (NH ₃ ) is a compound of hydrogen and nitrogen that is colorless, has a pungent odor, and exists in a gaseous state at room temperature. There are three hydrogen atoms forming an equilateral triangle with a side of 0.163 nm, and the nitrogen atom is floating 0.038 nm from the center of the equilateral triangle, showing a triangular pyramid-shaped molecular structure. The nitrogen atom that makes up ammonia has a pair of lone electrons, which allows ammonia to act as a proton acceptor, that is, a base. Due to its triangular pyramidal molecular structure, the dipole moment of ammonia is not 0, making it a polar substance. Ammonia forms hydrogen bonds, and the length of the NH bond in an ammonia molecule is 0.1014 nm, and the bond angle of HNH is 107°. It is contained in small amounts in the air, in natural water, and may also exist in soil as it is produced during the process of bacterial decomposition of nitrogenous organic matter.

Ammonia is used as an ingredient in synthetic fertilizers. Nitrogen is one of the essential elements for plant growth. Naturally, nitrogen fixation occurs in which some bacteria in the soil fix nitrogen in the air into nitrogen compounds, and through this, plants can absorb nitrogen. Urea fertilizer, made using ammonia synthesized by fixing nitrogen in the air, acts as a nitrogen source in the soil and provides abundant nitrogen to crops, resulting in increased crop production.

Ammonium nitrate, a nitrate of ammonia with the chemical formula NH ₄ NO ₃ , is relatively safe even at about 200°C, but when mixed with fuel such as petroleum, it acts as a strong oxidizing agent and causes an explosion. Bombs manufactured using these properties of ammonium nitrate are called fertilizer bombs, and this is an example of ammonia being used as a raw material for explosives. In addition to being used as a raw material for the synthesis of ammonium salts, nitric acid, and urea, ammonia is also used as a raw material for various chemical industries, for the production of ammonia water, and as a solvent for ionic substances.

The Haber-Bosch process, the most common method of producing ammonia, combines gaseous hydrogen and nitrogen at high temperature (e.g., 475°C) and high pressure (e.g., 20 MPa) on a metal catalyst to produce ammonia molecules as shown in Scheme 1, generating 100 kJ of energy. Shiki is an exothermic process. Although this process is a proven large-scale industrial process, it not only has a low reaction yield of 10 to 20%, but also consumes the second largest amount of energy in the world (average 32 GJ/ton NH ₃ ) and produces hydrogen from natural gas or coal. Therefore, it has the problem of emitting a large amount of CO ₂ (3.45 kg CO ₂ /kg NH ₃ ).

[Scheme 1]

N ₂ + 3H ₂ -> 2NH ₃ + 100kJ

Much research has been conducted to solve the shortcomings of the Haber-Bosch method. Among these, the electrochemical ammonia synthesis method using a proton conductive separator is different from the existing Haber-Bosch method by ionizing not only hydrogen but also the hydrogen contained in water into protons to produce nitrogen. It has the advantage of being able to react with gas at normal pressure (1 atmosphere).

However, in this electrochemical ammonia synthesis method, the amount of proton ionization of hydrogen and water is controlled according to the supplied current, so the ammonia yield can be precisely controlled according to the applied external current. However, the noble metal and conductive oxide electrode catalyst used causes oxygen and water dissociation. This catalyst has a very low nitrogen dissociation activity, so it has the disadvantage of having a low ammonia yield compared to the externally applied current. Therefore, compared to the Haber-Bosch method, equivalent or more energy is required to synthesize the same amount of ammonia.

U.S. Patent Publication No. 2012-0241328 (September 27, 2012)

The present invention was developed to solve the above problems. Specifically, by using a metallic compound containing a transition metal as a catalyst, it is much more effective than the existing Haber-Bosch process or electrochemical synthesis method. This relates to a low-temperature synthesis method of ammonia from water and air using a nitride catalyst, which enables large-scale synthesis of ammonia even at low temperature and pressure or low energy, and enables eco-friendly ammonia synthesis using only water and air.

The present invention relates to a nitride catalyst for low-temperature synthesis of ammonia and a method for low-temperature synthesis of ammonia from water and air using the nitride catalyst.

One aspect of the present invention relates to a nitride catalyst for low-temperature synthesis of ammonia having the composition of formula 1 below.

[Equation 1]

M _2-x R _x Si _y N _z

(In Formula 1, M is any one element selected from magnesium, calcium, strontium, and barium, and R is lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, It is any one element selected from ytterbium, lutetium, nickel, iron, molybdenum, and tungsten, and 0≤x≤2, 4≤y≤6, and 7≤z≤9.)

At this time, in the above formula 1, more preferably, M is any one selected from calcium, strontium and barium, R is europium, erbium, iron and tungsten, x is 0.001≤x≤0.5, and z is 7.5≤z Each is characterized by being ≤8.5.

Another aspect of the present invention is,

a1) preparing a slurry by mixing the catalyst for low-temperature synthesis of ammonia with distilled water;

b1) injecting one or more gases selected from nitrogen, hydrogen, air, and water vapor into the slurry into the reactor; and

c1) heating the reactor to a temperature of 30 to 100° C.;

Includes, or

a2) injecting a catalyst for low-temperature synthesis of ammonia into the reactor;

b2) injecting one or more gases selected from nitrogen, hydrogen, air, and water vapor into the reactor; and

c2) heating the reactor to a temperature of 30 to 100° C.;

It relates to a low-temperature synthesis method of ammonia from water and air using a nitride catalyst, comprising:

The catalyst according to the present invention contains a metal compound containing a transition metal as a main component, so that it can produce large quantities even at a much lower temperature and pressure or lower energy than the existing Haber-Bosch process or electrochemical synthesis method. It is possible to synthesize ammonia, and at the same time, it has the advantage of being able to synthesize environmentally friendly ammonia that does not produce impurities such as carbon dioxide using water and air.

In addition, it consumes much less energy than the electrical synthesis method, and because it does not use electrodes, there is no risk of corrosion and the creation of additional impurities can be suppressed.

Figure 1 shows the results of ammonia synthesis when using the catalysts of Examples 1 to 4.
Figure 2 shows the results of ammonia synthesis when using the catalysts of Examples 3, 5 to 8.
Figure 3 shows the results of ammonia synthesis when using the catalysts of Examples 6, 9 to 12.

Hereinafter, the nitride catalyst for low-temperature synthesis of ammonia according to the present invention and the low-temperature synthesis method of ammonia from water and air using the same will be described in more detail through examples and comparative examples. However, the specific examples introduced below are provided as examples so that the idea of the present invention can be sufficiently conveyed to those skilled in the art.

Therefore, the present invention is not limited to the specific examples presented below and may be embodied in other forms. The specific examples presented below are only described to clarify the spirit of the present invention, and the present invention is not limited thereto.

At this time, if there is no other definition in the technical and scientific terms used, they have meanings commonly understood by those skilled in the art to which this invention pertains, and the following description will not unnecessarily obscure the gist of the present invention. Descriptions of possible notification functions and configurations are omitted.

Additionally, as used in the specification and appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly dictates otherwise.

In the present invention, the terms ‘catalyst composition’ and ‘catalyst’ are synonymous and can be used interchangeably.

In the present invention, 'transition metals' include lanthanide elements including lanthanide (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), and terbium ( Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), nickel (Ni), iron (Fe), molybdenum (Mo) and tungsten (W). However, promethium (Pm), one of the lanthanide elements, is excluded because the amount that naturally exists in the earth's crust is extremely small (approximately 600 g) and its production method is very difficult.

While conducting extensive research to solve the problems of the existing ammonia production method, the Haber-Bosch method, such as low yield, excessive energy consumption, and carbon dioxide production, the present invention was developed using nitrides containing group 2 elements, silicon, and nitrogen. The present invention was completed by discovering that nitrogen in the air could be synthesized into ammonia even at relatively low temperatures (below 100°C) and normal pressure when doped with metal.

The catalyst for low-temperature synthesis of ammonia according to the present invention may have the form of a metal nitride as shown in Formula 1 below.

[Equation 1]

M _2-x R _x Si _y N _z

In the present invention, x refers to the number of rare earth metal (lanthanide metal) atoms for producing a catalyst. x may be influenced by the number of metal atoms other than rare earth metals, and x is 0 or more, It is an integer of 2 or less.

For example, in the above catalyst, when R is 0.7, M becomes 1.3, and when R is 1, M becomes 1, resulting in a partial or full substitution relationship. However, as described above, since x includes 0 and 2, one of M and R must be included, but one of the two may not be included.

As described above, x is an integer of 0 or more and 2 or less, and more preferably 0.001≤x≤0.5. When x is outside the above range, the crystal structure collapses, so it cannot function as a catalyst and the reliability of the catalyst decreases.

In Formula 1, M is a metal atom other than rare earth metals. For example, M may be any one element selected from magnesium, calcium, strontium, and barium. Among these, calcium, strontium, and barium are ammonia. It is desirable because of its high synthesis effect.

In addition, in the present invention, R is a transition metal atom, for example R is lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, nickel, iron, mol. It is any one element selected from libdenium and tungsten, and among these, those containing europium, erbium, iron, molybdenum, and tungsten are preferred because they have a high ammonia synthesis effect.

The transition metal serves to facilitate ammonia synthesis by lowering the energy required to separate the N≡N bond of nitrogen molecules (N ₂ ) and the OH bond of water molecules (H ₂ O) in the air.

In Equation 1, z refers to the number of nitrogen atoms for producing a catalyst, and z may be influenced by the number of group 2 elements and silicon atoms, and z is 7 or more and 9 or less, more preferably Typically, it is an integer in the range 7.5≤z≤8.5.

The nitrogen plays a role in forming ammonia by temporarily combining with hydrogen atoms decomposed from water molecules during ammonia synthesis. When the nitrogen position in the crystal structure becomes vacant due to the formed ammonia, nitrogen in the air fills the empty position.

In the formula 1, x is an integer of 0 or more and 2 or less, as described above, and z is preferably 7 or more and less than 9, and more preferably x and z are 0.001≤x≤0.5 and 7.5≤z, respectively. ≤8.5 is good.

In the present invention, the catalyst is not limited to a production method, and may be produced by any of the numerous methods of catalyst production known to those skilled in the art. A typical manufacturing method involves forming a mixture of a Group 2 metal halide, a transition metal oxide, silicon, and a reducing agent material and then subjecting it to a combustion reaction.

In the present invention, the Group 2 metal halide may be any one or more selected from the above-mentioned magnesium halide, calcium halide, strontium halide, and barium halide, and specifically, MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ , MgCl ₂ , CaCl ₂ , SrCl ₂ , BaCl ₂ , MgBr ₂ , CaBr ₂ , _{SrBr 2 , BaBr 2 , MgI 2 , CaI 2 , SrI 2 and BaI 2 It may be any one} or a mixture of two or more selected from among.

In particular, the Group 2 metal halide reacts with a reducing agent to cause an exothermic reaction, and the heat generated during the reduction/nitridation reaction can form a nitride catalyst.

The transition metal oxide is La ₂ O ₃ , CeO ₂ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ It may be any one or a mixture of two or more selected from O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , NiO, Fe ₂ O ₃ , MoO ₃ and WO ₃ , among which It may be more preferable that it is one or more selected from Eu ₂ O ₃ , Er ₂ O ₃ , Fe ₂ O ₃ , MoO ₃ and WO ₃ .

The silicon (Si) is used to generate an exothermic reaction necessary for a combustion reaction, and may be a powder particle with a particle size of 0.01 to 15 ㎛ in order to cause a more active combustion reaction.

The reducing agent may be any one or a mixture of two or more selected from lithium azide (LiN ₃ ), sodium azide (NaN ₃ ), and potassium azide (KN ₃ ). The reducing agent can reduce Group 2 metal halides and transition metal oxides, and is converted to LiF, LiCl, NaF, NaCl, KF, and KCl after combustion reaction, which can be removed through a leaching process using distilled water.

The reducing agent may be included in an amount of 1 to 20 moles per mole of the Group 2 metal halide. If it is outside the above range, reduction reaction or leaching may not occur properly.

The composition ratio of the mixture is not limited, but it is preferable to adjust the ratio within a range that satisfies the composition ratio of the catalyst described above. In this case, whether or not the precursor compound of each element is added can be determined depending on the form and composition of the produced catalyst, especially In addition to the essential silicon and nitrogen compounds, it may be decided whether to add a transition metal compound or a Group 2 metal halide.

For example, when x is 0 in Equation 1, the transition metal is not included. Therefore, when manufacturing a metal catalyst with the composition ratio as above, the composition ratio of the Group 2 metal compound is fixed to 2, and the composition ratio of the silicon compound and nitrogen compound is fixed to 2. The composition ratio may be in the range of 4 to 6:7 to 9, respectively.

Conversely, when x is 2, the Group 2 metal is not included, so when preparing a metal catalyst with the above composition ratio, the composition ratio of the transition metal compound is fixed to 2, and only the composition ratio of the silicon compound and nitrogen compound is 4 to 6:7, respectively. It may be included in the range of 9 to 9.

In addition, when both a transition metal and a Group 2 metal are included, it is recommended that the composition ratio of the Group 2 metal halide, transition metal oxide, silicon, and reducing agent be 0.001 to 2:0.001 to 2:4 to 6:7 to 9. .

The mixing method is not limited, but mixing using a ball mill may be preferable for rapid processing and uniform mixing.

The reaction mixture obtained by the above mixing can be filled into a container and made into a pellet form. The container can be a cup, and the cup can be cylindrical or rectangular.

The cup can be manufactured from various types of ingredients such as paper, metal, or quartz, and the obtained pellets have a density of 0.7 to 2.0 g/cm ³ , preferably 0.9 to 1.2 g/cm ³ to prevent ignition during combustion reaction. and combustion reaction can be carried out smoothly, but it is not necessarily limited to this.

The pelletized reaction mixture may be ignited from a heat source to initiate a combustion reaction, and the heat source may be a heat source based on metal wire resistance.

The combustion process used in the present invention is preferably carried out under high pressure conditions, and can be carried out in a high pressure reactor under a nitrogen atmosphere. At this time, the reaction pressure of nitrogen may be 0.5 to 5 MPa, preferably 1 to 3 MPa.

The combustion reaction is a self-sustaining reaction, and once the reaction starts by ignition, no external heat source supply is required and the reaction can be carried out quickly along the reaction raw materials at a speed of 0.1 to 0.5 cm/sec. .

The nitride catalyst of the present invention can be obtained by performing a combustion reaction and then washing and leaching the product.

The washing can be done using a conventional method, preferably using distilled water, and can be washed more than once.

The leaching can be performed using a conventional method, and it is preferable to use a hydrochloric acid solution or a sulfuric acid solution to prevent a decrease in the synthesis efficiency of the prepared transition nitride catalyst due to impurities.

The present invention may include a method of synthesizing ammonia using a nitride catalyst for low-temperature synthesis of ammonia prepared as described above. At this time, the method for synthesizing ammonia is,

a1) preparing a slurry by mixing a catalyst for low-temperature synthesis of ammonia prepared by the above method with distilled water;

b1) injecting one or more gases selected from nitrogen, hydrogen, air, and water vapor into the slurry into the reactor; and

c1) heating the reactor to a temperature of 30 to 100° C.;

Includes, or

a2) injecting a catalyst for low-temperature synthesis of ammonia into the reactor;

b2) injecting one or more gases selected from nitrogen, hydrogen, air, and water vapor into the reactor; and

c2) heating the reactor to a temperature of 30 to 100° C.;

may include.

The above ammonia production methods are basically the same as mixing a catalyst, water, and air in a reactor and heating to a low temperature of 100°C or lower for reaction. The only difference is that the catalyst and water are mixed first or the water and air are mixed first. , there is no difference in the yield of ammonia regardless of which method is applied.

The ammonia synthesis mechanism of the catalyst for ammonia synthesis according to the present invention can be explained in two ways. First, when multiple water molecules come into contact with the catalyst, nitrogen atoms in the catalyst's crystal structure temporarily combine with three hydrogen atoms of the water molecules to form ammonia (NH ₃ ) and hydroxide ions (OH ^- ). The formed ammonia is separated from the catalyst and a vacancy for a nitrogen atom is created in the catalyst. At this time, the adjacent transition metal atom separates the bond of the nitrogen molecule adsorbed to the catalyst from the air and fills the empty space with the separated nitrogen atom. In this way, the catalyst returns to its original state and repeats the same process to produce ammonia.

Another mechanism is that when the catalyst and air come into contact, nitrogen molecules are adsorbed to the transition metal atoms in the crystal structure of the catalyst. At this time, when the transition metal atom separates the bond of the nitrogen molecule and takes nitrogen atoms one by one, the nitrogen atom combines with the hydrogen atom of the water molecule to generate ammonia (NH ₃ ) and hydroxide ion (OH ^- ). When the ammonia produced in this way is separated from the catalyst, the catalyst returns to its original state and can produce ammonia by combining with other nitrogen molecules.

The above reaction begins as soon as nitrogen or water molecules in the air come into contact with the catalyst, and since temperature or pressure do not affect the activation of the catalyst, it has the advantage of being able to synthesize ammonia even at low temperature or normal pressure. . However, as mentioned above, since the number of contacts between nitrogen molecules and the catalyst is directly related to the yield of ammonia, it is necessary to heat the catalyst to a certain temperature or higher to promote the movement of nitrogen molecules.

As described above, in the present invention, the water provides the hydrogen necessary for ammonia synthesis, and the air acts as a source of nitrogen, and if necessary, ammonia sources such as nitrogen, hydrogen, and water vapor are separately used to promote the reaction. The gas can be further mixed and injected into the reactor.

At this time, the mixing ratio of each composition in the ammonia synthesis method is not limited, and in fact, there is no upper limit for water or air compared to the catalyst, but from an economical perspective, 50 to 300 parts by weight of water and 15 to 100 parts by weight of air relative to 100 parts by weight of the catalyst. It is mixed by weight, but since the synthesis yield of ammonia increases when nitrogen is supplied excessively, it is better to prepare it with a composition ratio of water and air that satisfies 1 to 3:1. Within the above range, the unreacted composition can be reduced and the generated ammonia can be prevented from dissolving in water.

In the present invention, the ammonia synthesis method preferably involves heating the above-described compositions for a certain period of time after they are added into the reactor to promote the reaction. At this time, the heating temperature is not limited, but heating to a temperature of 30 to 100°C is preferable in terms of energy saving.

The catalyst according to the present invention synthesizes a large amount of ammonia at a much lower temperature or under lower energy than the existing Haber-Bosch process or electrochemical synthesis method by containing a metal compound containing a transition metal as a main component. This is possible, and at the same time, it has the advantage of being able to synthesize environmentally friendly ammonia that does not produce impurities such as carbon dioxide using water and air.

In addition, it consumes much less energy than the electrical synthesis method, and because it does not use electrodes, there is no risk of corrosion and the creation of additional impurities can be suppressed.

Hereinafter, the present invention will be described in more detail through examples and comparative examples. However, the following examples and comparative examples are only examples to explain the present invention, and the present invention is not limited to the following examples.

(Example 1)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), eurobium oxide (Eu ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder After weighing at a molar ratio of 1.93:0.07:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 30°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 2)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), eurobium oxide (Eu ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder After weighing at a molar ratio of 1.93:0.07:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 40°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 3)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), eurobium oxide (Eu ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder After weighing at a molar ratio of 1.93:0.07:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 4)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), eurobium oxide (Eu ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder After weighing at a molar ratio of 1.93:0.07:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 70°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 5)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), eurobium oxide (Eu ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder After weighing at a molar ratio of 1.95:0.05:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed for 24 hours using a ball mill. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 6)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), eurobium oxide (Eu ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder After weighing at a molar ratio of 1.97:0.03:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 7)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), eurobium oxide (Eu ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder After weighing at a molar ratio of 1.99:0.01:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 8)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), silicon (Si, Samchun Chemical, S2381), and sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder were weighed at a molar ratio of 2.0:5.0:4.0, then zirconia balls. was mixed at a weight ratio of 1/2 of the raw materials and mixed for 24 hours using a ball mill. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 9)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), iron oxide (Fe ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder at 1.97: After weighing at a molar ratio of 0.03:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 10)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), samarium oxide (Sm ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder at 1.97% After weighing at a molar ratio of : 0.03 : 5.0 : 4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3L) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 11)

Strontium chloride (SrCl ₂ , Daejung Chemical Gold), nickel oxide (NiO, Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder at 1.97:0.03: After weighing at a molar ratio of 5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

(Example 12)

Barium chloride (BaCl ₂ , Daejung Chemical Gold), eurobium oxide (Eu ₂ O ₃ , Alfa Aesar), silicon (Si, Samchun Chemical, S2381), sodium azide (NaN ₃ , Daejung Chemical Gold, 255S0074) powder After weighing at a molar ratio of 1.97:0.03:5.0:4.0, zirconia balls were mixed at a weight ratio of 1/2 of the raw materials and mixed using a ball mill for 24 hours. The mixture was placed in a high-purity alumina refractory container, pressurized at 5Mpa and stacked, placed in a reactor, and the purge process of filling and vacuuming nitrogen gas was repeated three times, and the inside of the reactor was filled with 20 atm of nitrogen gas to maintain it. . The laminated raw materials were ignited using a hot wire to cause a combustion reaction to synthesize the powder. After washing the synthesized powder with water twice, it was mixed with an HCl solution of pH 1 and stirred for 2 hours, and then the powder was separated, recovered, and washed with water. The recovered powder was dried at 100°C for 2 hours to prepare a nitride catalyst.

1g of the prepared catalyst powder was mixed with 2g of distilled water to create a slurry. The prepared slurry was placed in a reactor (3 liters) and heated to 50°C to produce ammonia. The degree of ammonia production was confirmed by measuring the UV-vis spectrum using the Indophenol method.

Figure 1 shows the results of ammonia synthesis according to Examples 1, 2, 3, and 4. From the above results, it was confirmed that the ammonia synthesis efficiency increased as the temperature increased.

Figure 2 shows the results of ammonia synthesis according to Examples 3, 5, 6, 7, and 8 at 50°C. As shown in the above results, it can be seen that the ammonia synthesis efficiency changes depending on the doping amount of the transition metal. In particular, it can be seen that the ammonia synthesis efficiency is highest when 0.03 mol of europium is doped as in Example 6.

Figure 3 shows the results of ammonia synthesis according to Examples 6, 9, 10, 11, and 12 at 50°C. As shown in the above results, it can be seen that the synthesis efficiency of ammonia varies depending on the type of transition metal. In particular, it can be seen that the nitride doped with eurobium as in Example 6 has the highest ammonia synthesis efficiency, and the iron in Example 9 It can be seen that similar efficiency is observed even when doped.

Preferred embodiments of the present invention have been described above, but the scope of the present invention is not limited to the specific embodiments described above, and those skilled in the art will understand the appropriate embodiments within the scope described in the claims of the present invention. It will be possible to change it.

Claims (7)

A nitride catalyst for low-temperature synthesis of ammonia having the composition of formula 1 below.
[Equation 1]
M _2-x R _x Si _y N _z
(In Equation 1 above,
M is any element selected from strontium and barium,
R is any element selected from samarium, europium, nickel, and iron,
0≤x≤2,
4≤y≤6,
7≤z≤9.)
delete delete According to clause 1,
A nitride catalyst for low-temperature synthesis of ammonia, wherein x is 0.001≤x≤0.5.
According to clause 1,
A nitride catalyst for low-temperature synthesis of ammonia, wherein z is 7.5≤z≤8.5.
a1) preparing a slurry by mixing a catalyst for low-temperature synthesis of ammonia according to any one of claims 1, 4, and 5 with distilled water;
b1) injecting one or more gases selected from nitrogen, hydrogen, air, and water vapor into the slurry into the reactor; and
c1) heating the reactor to a temperature of 30 to 100° C.;
A low-temperature synthesis method of ammonia from water and air using a nitride catalyst, comprising:
a2) injecting a catalyst for low-temperature synthesis of ammonia according to any one of claims 1, 4, and 5 into the reactor;
b2) injecting one or more gases selected from nitrogen, hydrogen, air, and water vapor into the reactor; and
c2) heating the reactor to a temperature of 30 to 100° C.;
A low-temperature synthesis method of ammonia from water and air using a nitride catalyst, comprising: