KR20230103894A - Monoclinic ruthenium oxide catalyst and method of preparing ammonia from nitrate using the same - Google Patents

Abstract

The present application relates to a ruthenium oxide catalyst and a method for producing ammonia from nitrate using the same.

Description

Monoclinic ruthenium oxide catalyst and method for producing ammonia from nitrate using the same

The present application relates to a monoclinic ruthenium oxide catalyst and a method for producing ammonia from nitrate using the same.

Ammonia is a source material used as a nitrogen source for nitrogen-containing compounds such as pesticides, medicines, fine chemicals, and explosives, and is also a necessary raw material for producing nitric acid, which is widely used in semiconductor, electronic material cleaning processes, or steel sheet pickling processes. Currently, ammonia is produced based on a process developed by Haber and Bosch in the 1920s, and is obtained by reacting hydrogen and nitrogen over an iron-based catalyst at about 450° C. and 20 MPa. Since the Haber-Bosch process requires high temperature and high pressure conditions, it is an energy-intensive process requiring high operating costs. In addition, since hydrogen necessary for producing ammonia is obtained through a reforming reaction of coal or methane using water vapor, dependence on fossil fuels is high, and thus a large amount of carbon dioxide, a greenhouse gas, is emitted during the manufacturing process.

On the other hand, a process for producing ammonia from nitrogen oxides (NO _x ) can be produced with much less energy compared to the Haber-Bosch process. As an example, the hydrogenation reaction of nitrate (NO ₃ ^- ) ions is exothermic and spontaneous (ΔH < 0 and ΔG < 0), and conversion to nitrogen or ammonia is easy. Nitrogen oxide is mixed with various waste solutions or by-product gases generated from combustion processes, and since it is harmful to the human body and has a bad effect on the environment, it must be converted to harmless nitrogen, oxygen, or water and discharged. The conversion of nitrogen oxides present in waste or by-product gases into value-added products such as ammonia is of great importance both from an environmental and economical point of view. Thus, catalytic conversion of nitrogen oxides into ammonia provides a solution to restore imbalance in the global nitrogen cycle and at the same time provides a sustainable alternative to the Haber-Bosch process.

In this context, research on converting nitrate ions into ammonia through an electrochemical catalytic reduction reaction has recently been rapidly increasing. Although this electric reduction method is a powerful alternative, it is still not a mass production technology that can be used in industry due to a low ammonia production rate and side reactions such as hydrogen generation reaction. Therefore, in order to implement a process capable of economically and efficiently producing ammonia from nitrogen oxides, it is necessary to develop a hydrogenation catalyst that can be produced at a mass production level and has high ammonia generation yield and selectivity.

Japanese Patent Registration No. 6675619.

The present application is to provide a monoclinic ruthenium oxide catalyst and a method for producing ammonia from nitrate using the same.

However, the problem to be solved by the present application is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

A first aspect of the present application provides a catalyst comprising a monoclinic ruthenium oxide represented by the following formula (I), which is used for producing ammonia through a hydrogenation reaction of nitrogen oxides:

[Formula I]

H _x RuO ₂ ;

In Formula I, 0<x≤4.

A second aspect of the present application provides a method for producing ammonia, comprising obtaining ammonia by supplying hydrogen gas to the catalyst and nitrate according to the first aspect for a hydrogenation reaction.

Catalysts according to embodiments of the present application have excellent reaction activity and can produce ammonia in high yield.

Catalysts according to embodiments of the present application do not change or decompose under acidic or basic conditions and can be used for long-term hydrogenation reactions.

Catalysts according to embodiments of the present application have strong chemical resistance, and can reduce ruthenium melting or structural collapse.

Catalysts according to the embodiments of the present application, including interstitial hydrogen, can prevent a reaction that is reduced to ruthenium metal in a hydrogenation reaction.

The catalyst according to the embodiments of the present application can be easily separated from ammonia, which is a product of the hydrogenation reaction, and reused.

1 is an X-ray powder diffraction analysis graph of the primary precipitate in Example 1 of the present application.
2 is an X-ray powder diffraction analysis graph of the secondary precipitate (ammonium sulfate ((NH ₄ ) ₂ SO ₄ )) in Example 1 of the present application.

Hereinafter, with reference to the accompanying drawings, embodiments and embodiments of the present application will be described in detail so that those skilled in the art can easily practice the present invention. However, the present disclosure may be embodied in many different forms and is not limited to the implementations and examples described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout this specification, when a part is said to be "connected" to another part, this includes not only the case of being "directly connected" but also the case of being "electrically connected" with another element in between. do.

Throughout the present specification, when a member is said to be located “on” another member, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members.

Throughout the present specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

As used herein, the terms "about," "substantially," and the like are used at or approximating that number when manufacturing and material tolerances inherent in the stated meaning are given, and are intended to assist in the understanding of this disclosure. Accurate or absolute figures are used to prevent undue exploitation by unscrupulous infringers of the stated disclosure.

The term "step of" or "step of" used throughout the present specification does not mean "step for".

Throughout this specification, the term "combination(s) of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, It means including one or more selected from the group consisting of the above components.

Throughout this specification, reference to "A and/or B" means "A or B, or A and B".

Hereinafter, embodiments of the present application have been described in detail, but the present application may not be limited thereto.

A first aspect of the present application provides a catalyst comprising a monoclinic ruthenium oxide represented by the following formula (I), which is used for producing ammonia through a hydrogenation reaction of nitrogen oxides:

[Formula I]

H _x RuO ₂ ;

In Formula I, 0<x≤4.

In one embodiment of the present application, in Formula I, x (atomic ratio of hydrogen) is greater than 0 and less than or equal to 4, about 0.1 to about 3.5, about 0.1 to about 3, about 0.1 to about 2.5, about 0.1 to about 2, About 0.1 to about 1.5, about 0.1 to about 1.2, about 0.2 to about 3.5, about 0.2 to about 3, about 0.2 to about 2.5, about 0.2 to about 2, about 0.2 to about 1.5, about 0.2 to about 1.2, about 0.3 to about 3.5, about 0.3 to about 3, about 0.3 to about 2.5, about 0.3 to about 2, about 0.3 to about 1.5, about 0.3 to about 1.2, about 0.4 to about 3.5, about 0.4 to about 3, about 0.4 to It may be about 2.5, about 0.4 to about 2, about 0.4 to about 1.5, or about 0.4 to about 1.2, but may not be limited thereto. In one embodiment of the present application, in Formula 1, x may be from about 0.4 to about 1.2.

In one embodiment of the present application, in Chemical Formula I, the closer x (atomic ratio of hydrogen) is to about 1, the easier it is to generate the monoclinic structure of ruthenium oxide. Specifically, in Chemical Formula I, when the hydrogen ratio is from about 0.6 to about 1.4, it may be easier to generate the monoclinic ruthenium oxide. Here, when x is 0 in Formula I, a structural transition from a tetragonal rutile structure to ruthenium oxide may occur, and thus, it is preferable to maintain the hydrogen content.

In one embodiment of the present application, the atomic ratio of hydrogen contained in Formula 1 may be calculated by thermo-gravimetric analysis (TGA). Specifically, in the analysis using the thermal gravimetric analysis, the weight change may be measured while raising the temperature after putting the solid sample in a platinum container. All hydrogen contained in the monoclinic ruthenium oxide (H _x RuO ₂ ) is removed and converted to tetragonal ruthenium oxide (RuO ₂ ). The amount of hydrogen can be quantitatively analyzed from the weight change according to temperature.

In one embodiment of the present application, the monoclinic ruthenium oxide has an incident angle (2θ) of 18.38 ° < 2θ <18.42 °, 25.45 ° < 2θ <25.51 °, 26.26 ° by X-ray powder diffraction measurement (Cu Kα ray) < 2θ <26.32°, 33.45°< 2θ <33.51°, 35.28°< 2θ <35.34°, 36.24°< 2θ <36.30°, 37.32°< 2θ <37.38°, 39.55°< 2θ <39.61°, 40.61°< 2θ <40.67°, 41.46°< 2θ <41.52°, 49.17°< 2θ <49.23°, 52.31°< 2θ <52.37°, 54.03°< 2θ <54.09°, 54.70°< 2θ <54.76°, 55.95°< 2θ <56.01 °, 59.97°< 2θ <60.03°, 60.40°< 2θ <60.46°, 61.92°< 2θ <61.98°, 63.94°< 2θ <64.00°, 65.79°< 2θ <65.85° and 69.13°< 2θ <69.19° A diffraction peak may be observed at each position. In one embodiment of the present application, the monoclinic ruthenium oxide has an incident angle (2θ) determined by X-ray powder diffraction measurement (Cu Kα ray) of 18.40°, 25.48°, 26.29°, 33.48°, 35.31°, 36.27° , 37.35°, 39.58°, 40.64°, 41.49°, 49.20°, 52.34°, 54.06°, 54.73°, 55.98°, 58.00°, 60.43°, 61.95°, 63.97°, 65.82° and 69.16° diffraction at each position A peak may be observed.

In one embodiment of the present application, the monoclinic ruthenium oxide may have a monoclinic space group P2 ₁ /c, C2/m, P2/c, C2/c, P2/m, or P2 ₁ /m structure. , may not be limited thereto.

In one embodiment of the present application, the unit cell of the monoclinic crystal structure of the monoclinic ruthenium oxide can be represented as shown in the figure below, and the lattice constants a to c and the angle between the corners are defined as follows can be:

In one embodiment of the present application, in the monoclinic structure, 5 Å ≤ a ≤6 Å, 5 Å ≤ b ≤6 Å, and 5 Å ≤ c ≤6 Å, and the beta (β) angle is from about 110 ° to It may be about 120°. For example, the a to c are each independently about 5 Å to about 6 Å, about 5.1 Å to about 6 Å, about 5.2 Å to about 6 Å, about 5.3 Å to about 6 Å, about 5 Å to about 5.8 Å, from about 5.1 Å to about 5.8 Å, from about 5.2 Å to about 5.8 Å, from about 5.3 Å to about 5.8 Å, from about 5 Å to about 5.6 Å, from about 5.1 Å to about 5.6 Å, from about 5.2 Å to about 5.6 Å , from about 5.3 Å to about 5.6 Å, from about 5 Å to about 5.4 Å, from about 5.1 Å to about 5.4 Å, from about 5.2 Å to about 5.4 Å, from about 5.3 Å to about 5.4 Å, or from about 5.35 Å to about 5.4 Å. And, b is about 5 Å to about 6 Å, about 5 Å to about 5.8 Å, about 5 Å to about 5.6 Å, about 5 Å to about 5.4 Å, about 5 Å to about 5.2 Å, or about 5 Å to about 5.1 Å, the beta (β) angle is about 110 ° to about 120 °, about 112 ° to about 120 °, about 114 ° to about 120 °, about 110 ° to about 118 °, about 112 ° to about 118°, about 114° to about 118°, about 110° to about 116°, about 112° to about 116° or about 114° to about 116°.

In one embodiment of the present application, in the monoclinic structure, a = 5.3533 Å, b = 5.0770 Å, c = 5.3532 Å, and a beta (β) angle may be 115.9074 °, but may not be limited thereto.

A second aspect of the present application provides a method for producing ammonia, comprising obtaining ammonia by supplying hydrogen gas to the catalyst and nitrate according to the first aspect for a hydrogenation reaction.

Detailed descriptions of portions overlapping with the first aspect of the present application have been omitted, but the description of the first aspect of the present application can be equally applied even if the description is omitted in the second aspect of the present application.

In one embodiment of the present application, the ammonia production method may be to obtain ammonia by supplying hydrogen gas to an aqueous solution containing the catalyst and the nitrate for a hydrogenation reaction.

In one embodiment of the present application, the nitrate may be a metal nitrate, but may not be limited thereto. In one embodiment of the present application, the metal may include one or more selected from alkali metals, alkaline earth metals, and transition metals. In one embodiment of the present application, the metal may include one or more selected from Ca, Na, K, Mg, Zn, and Fe, but may not be limited thereto. In one embodiment of the present application, the metal nitrate is one selected from Ca(NO ₃ ) ₂ , Zn(NO ₃ ) ₂ , NaNO ₃ , KNO ₃ , Mg(NO ₃ ) ₂ , and Fe(NO ₃ ) ₃ It may include the above, but may not be limited thereto. In one embodiment of the present application, the metal nitrate may be a metal nitrate hydrate, but may not be limited thereto. In one embodiment of the present application, the metal nitrate may exist as a metal cation and a nitrogen oxide anion in an aqueous solution, and the nitrogen oxide anion may be NO ₃ ^- or NO ₂ ^- .

In one embodiment of the present application, the concentration of the nitrate may be about 0.1 M to 0.5 M, but may not be limited thereto. In one embodiment of the present application, the concentration of the nitrate may mean the concentration in the aqueous solution. In one embodiment of the present application, the concentration of the nitrate is about 0.1 M to about 5 M, about 0.1 M to about 4 M, about 0.1 M to about 3 M, about 0.5 M to about 5 M, about 0.5 M to about It may be 4 M, about 1 M to about 3 M, about 1 M to about 5 M, about 1 M to about 4 M, or about 1 M to about 3 M, but may not be limited thereto. In one embodiment of the present application, when the concentration of nitrate is less than about 0.1 M, the rate of production of ammonia slows down, and when the concentration of nitrate is greater than about 5 M, ammonia due to solubility of ammonia present in an aqueous solution after the reaction production may decrease.

In one embodiment of the present application, based on 100 parts by weight of the nitrate, the catalyst may be from about 0.1 part by weight to about 10 parts by weight, but may not be limited thereto. In one embodiment of the present application, based on 100 parts by weight of the nitrate, the catalyst is about 0.1 part by weight to about 10 parts by weight, about 0.1 parts by weight to about 9 parts by weight, about 0.1 parts by weight to about 8 parts by weight, about 0.1 parts by weight About 7 parts by weight, about 0.1 part by weight to about 6 parts by weight, about 1 part by weight to about 10 parts by weight, about 1 part by weight to about 9 parts by weight, about 1 part by weight to about 8 parts by weight, about 1 About 7 parts by weight, about 1 part by weight to about 6 parts by weight, about 2 parts by weight to about 10 parts by weight, about 2 parts by weight to about 9 parts by weight, about 2 parts by weight to about 8 parts by weight, about 2 parts by weight About 7 parts by weight, about 2 parts by weight to about 6 parts by weight, about 3 parts by weight to about 10 parts by weight, about 3 parts by weight to about 9 parts by weight, about 3 parts by weight to about 8 parts by weight, about 3 parts by weight It may be from about 7 parts by weight to about 7 parts by weight, or about 3 parts by weight to about 6 parts by weight. In one embodiment of the present application, when the catalyst is less than about 0.1 parts by weight based on 100 parts by weight of the nitrate, the reaction time of the hydrogenation reaction may be prolonged and / or the reaction may not be completed, and 100 parts by weight of the nitrate If the amount of the catalyst is greater than about 10 parts by weight, by-products of the hydrogenation reaction may be generated, resulting in reduced selectivity of the final product.

In one embodiment of the present application, the ammonia production method may include putting an aqueous solution containing the catalyst and the nitrate into a hydrothermal reactor, and supplying the hydrogen gas to the hydrothermal reactor for a hydrogenation reaction to obtain ammonia. However, it may not be limited thereto.

In one embodiment of the present application, the supply pressure of the hydrogen gas may be about 0.1 MPa to about 10 MPa, but may not be limited thereto. In one embodiment of the present application, the hydrogen pressure is about 0.1 MPa to about 10 MPa, about 0.1 MPa to about 5 MPa, about 0.1 MPa to about 4 MPa, about 0.1 MPa to about 3 MPa, about 0.1 MPa to about 2 MPa, about 0.1 MPa to about 1.5 MPa, about 0.5 MPa to about 10 MPa, about 0.5 MPa to about 5 MPa, about 0.5 MPa to about 4 MPa, about 0.5 MPa to about 3 MPa, about 0.5 MPa to about 2 MPa , Or it may be from about 0.5 MPa to about 1.5 MPa, but may not be limited thereto. In one embodiment of the present application, the supply pressure of the hydrogen gas may be from about 0.5 MPa to about 1.5 MPa. In one embodiment of the present application, the supply pressure of the hydrogen gas is most preferably about 1 MPa.

In one embodiment of the present application, the hydrogenation reaction may be carried out at a temperature range of about 20 ℃ to about 200 ℃. In one embodiment of the present application, the hydrogenation reaction is about 20 ℃ to about 200 ℃, about 20 ℃ to about 180 ℃, about 20 ℃ to about 160 ℃, about 20 ℃ to about 140 ℃, about 20 ℃ to about 120 ℃ °C, about 20 °C to about 100 °C, about 40 °C to about 200 °C, about 40 °C to about 180 °C, about 40 °C to about 160 °C, about 40 °C to about 140 °C, about 40 °C to about 120 °C, About 40°C to about 100°C, about 60°C to about 200°C, about 60°C to about 180°C, about 60°C to about 160°C, about 60°C to about 140°C, about 60°C to about 120°C or about 60°C It may be carried out at a temperature range of ℃ to about 100 ℃.

In one embodiment of the present application, the nitrate conversion rate may be about 40% or more. In one embodiment of the present application, the conversion rate of the nitrate is about 40% or more, about 50% or more, about 60% or more, about 70% or more, about 80% or more, about 90% or more, about 40% to about 90% , about 40% to about 80%, about 40% to about 70%, about 40% to about 60%, about 40% to about 50%, about 50% to about 90%, about 50% to about 80%, about 50% to about 70%, about 50% to about 60%, about 60% to about 90%, about 60% to about 80%, about 60% to about 70%, about 70% to about 90%, about 70% to about 80% or about 80% to about 90%. Here, the conversion rate means the conversion rate of nitrate calculated by measuring NO ₃ ^- or NO ₂ ^- remaining in the supernatant using UV-visible spectroscopy after the hydrogenation reaction. That is, since the conversion rate represents the rate at which nitrate is converted into ammonium ions, it may be a numerical value that quantitatively indicates the effect of converting nitrate into ammonium ions according to the embodiments of the present application.

In one embodiment of the present application, the ammonia production method may further include separating the catalyst after the hydrogenation reaction. In one embodiment of the present application, the ammonia production method may further include separating a precipitate containing a metal hydroxide generated by the catalyst and the metal nitrate after the hydrogenation reaction.

In one embodiment of the present application, the ammonia production method may further include obtaining an ammonium salt by adding an inorganic acid to the mixture after the hydrogenation reaction. In one embodiment of the present application, the inorganic acid may be sulfuric acid, nitric acid, or acetic acid, but may not be limited thereto. In one embodiment of the present application, the ammonium salt is ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), nitric acid It may be ammonium (NH ₄ NO ₃ ) or ammonium acetate (NH ₄ CH ₃ CO ₂ ), and the ammonium salt may vary depending on the type of the inorganic acid. Here, the yield of ammonium ion can be calculated through the weight of the ammonium salt obtained by additional addition of inorganic acid, but this is experimentally obtained in the process of obtaining ammonium salt for separation and use of ammonium ion after generating ammonium ion from nitrate. It may be an additional number to be identified.

Hereinafter, the present application will be described in more detail using examples, but the following examples are only illustrative to aid understanding of the present application, and the content of the present application is not limited to the following examples.

[Example]

<Example 1>

Hydrogenation of nitrogen oxides was performed using H _x RuO ₂ as a catalyst. In a 10 mL pyrex glass container, add 10 mg of H _x RuO ₂ , 0.236 g (1 mmol) of calcium nitrate (Ca(NO ₃ ) ₂ 4H ₂ O) and 2 mL of distilled water together with a magnetic bar. and the glass container was reacted inside the hydrothermal reactor. The inside of the hydrothermal reactor was ventilated with hydrogen three times to remove oxygen, and then filled with hydrogen pressure of 1.0 MPa (10 bar). Thereafter, a hydrogenation reaction was performed for 1 hour by stirring at 600 rpm at a temperature of 100° C., the reactor was cooled to room temperature, and the primary precipitate was separated using a centrifuge. At this time, the amount of NO ₃ ^- and NO ₂ ^- remaining in the supernatant was confirmed using UV-visible spectroscopy, and ammonia (ammonium ion) conversion rate (%) was calculated therefrom, resulting in a conversion rate of 99.5%. Subsequently, sulfuric acid was added to the supernatant in which the ammonia component was dissolved to generate ammonium sulfate form, and then acetone was added as a secondary solvent to precipitate ammonium sulfate (secondary precipitate) using the difference in solubility. After the reaction, the primary precipitate and the solvent of the precipitated ammonium sulfate were dried, and then the structures were analyzed by X-ray diffraction analysis. The primary precipitates were calcium hydroxide (Ca(OH) ₂ ) and monoclinic ruthenium oxide (H _x RuO ₂ ), and it was confirmed that ammonium sulfate had a (NH ₄ ) ₂ SO ₄ crystal structure. The amount of ammonium sulfate produced was 0.098 g, and the yield calculated on the basis of calcium nitrate was 74.2%.

<Example 2>

The hydrogenation reaction was carried out in the same manner as in Example 1, except that the reaction was performed at a hydrogen pressure of 2.0 MPa (20 bar). As a result of X-ray diffraction analysis, it was confirmed that the primary precipitates were Ca(OH) ₂ and H _x RuO ₂ , and that ammonium sulfate had a (NH ₄ ) ₂ SO ₄ crystalline phase. The amount of ammonium sulfate produced was 0.114 g, and the yield calculated on the basis of calcium nitrate was 86.4%.

<Example 3>

The hydrogenation reaction was carried out in the same manner as in Example 1, except that the reaction was performed at a hydrogen pressure of 0.5 MPa (5 bar). As a result of X-ray diffraction analysis, the primary precipitates were Ca(OH) ₂ and H _x RuO ₂ . In addition, as a result of confirming the amount of NO ₃ ^- and NO ₂ ^- remaining in the supernatant using UV-visible spectroscopy, the conversion rate of calcium nitrate was 44.4%. The supernatant was treated with a sulfuric acid solution, and acetone was added as a secondary solvent to obtain a secondary precipitate using the difference in solubility. As a result of X-ray diffraction analysis, it was confirmed that it had a crystalline phase of CaSO ₄ . As such, when the ammonia conversion rate during the hydrogenation reaction of nitrate (Ca(NO ₃ ) ₂ ) is low, less than about 50%, the unreacted Ca(NO ₃ ) ₂ is still dissolved in the solution, and Ca ²⁺ ions of Ca(OH) Precipitation to ₂ occurs less. Therefore, when sulfuric acid is added, Ca ²⁺ ions and sulfuric acid react to form CaSO ₄ . The secondary precipitate contains both (NH ₄ ) ₂ SO ₄ and CaSO ₄ , but the CaSO ₄ peak in the X-ray diffraction measurement indicates that (NH ₄ ) ₂ SO ₄ Peaks are covered. That is, although ammonia was synthesized in Example 3, it is only difficult to quantitatively confirm the amount of ammonium sulfate produced. When the reaction pressure is low, the ammonia conversion rate can be increased by sufficiently extending the reaction time.

<Example 4>

The hydrogenation reaction was carried out in the same manner as in Example 1, except that 0.118 g (0.5 mmol) of calcium nitrate was reacted for 30 minutes. As a result of analyzing the crystal phase through X-ray diffraction, it was confirmed that the primary precipitates were Ca(OH) ₂ and H _x RuO ₂ , and that ammonium sulfate had a (NH ₄ ) ₂ SO ₄ crystal phase. The amount of ammonium sulfate produced was 0.058 g, and the yield calculated on the basis of calcium nitrate was 87.8%.

<Example 5>

A hydrogenation reaction was performed in the same manner as in Example 1, except that 4 mL of distilled water was added and reacted at 60° C. for 4 hours. As a result of X-ray diffraction analysis, the primary precipitates were Ca(OH) ₂ and H _x RuO ₂ . In addition, as a result of confirming the amount of NO ₃ ^- or NO ₂ ^- remaining in the supernatant using UV-visible spectroscopy, the conversion rate of calcium nitrate was 99.5%. After treating the supernatant with a sulfuric acid solution, acetone was added as a secondary solvent to obtain a precipitate, and as a result of X-ray diffraction analysis, ammonium sulfate was (NH ₄ ) ₂ SO ₄ and (NH ₄ ) ₃ H(SO ₄ ) It was confirmed to have _two crystal phases. The amount of ammonium sulfate produced was 0.106 g, and the yield calculated on the basis of calcium nitrate was 80.2%.

<Example 6>

A hydrogenation reaction was performed in the same manner as in Example 5, except that the reaction was performed at 80° C. for 1.5 hours. As a result of X-ray diffraction analysis, the primary precipitates were Ca(OH) ₂ and H _x RuO ₂ , and as a result of confirming the amount of NO ₃ ^- or NO ₂ ^- remaining in the supernatant using ultraviolet visible light spectroscopy, calcium nitrate The conversion rate was 99.6%. Ammonium sulfate was confirmed to have a (NH ₄ ) ₂ SO ₄ crystalline phase. The amount of ammonium sulfate produced was 0.102 g, and the yield calculated on the basis of calcium nitrate was 77.2%.

<Example 7>

The hydrogenation reaction was carried out in the same manner as in Example 1, except that 0.297 g (1 mmol) of zinc nitrate (Zn(NO ₃ ) ₂ 6H ₂ O) was used as the metal nitrate. As a result of X-ray diffraction analysis, the primary precipitates were ZnO and H _x RuO ₂ , and as a result of confirming the amount of NO ₃ ^- and NO ₂ ^- remaining in the supernatant using ultraviolet visible light spectroscopy, the conversion rate of zinc nitrate was 49.4% was The supernatant was treated with a sulfuric acid solution, and a secondary solvent was added to obtain a secondary precipitate due to the difference in solubility. As a result of X-ray diffraction analysis, it was found that the crystal phases of ZnSO ₄ and (NH ₄ ) ₂ SO ₄ were mixed. Confirmed. This means that when zinc nitrate is used as the metal nitrate, the reaction proceeds more slowly than calcium nitrate. As a secondary precipitate, ZnSO ₄ is produced in addition to (NH ₄ ) ₂ SO ₄ , so it is difficult to confirm the yield of ammonia by weight measurement and XRD analysis of the secondary precipitate, but ultraviolet-visible spectroscopy (UV-visible spectroscopy) As vis), the conversion rate of the zinc nitrate can be confirmed.

<Example 8>

The hydrogenation reaction was carried out in the same manner as in Example 1, except that 0.170 g (2 mmol) of sodium nitrate (NaNO ₃ ) was used as the metal nitrate. As a result of X-ray diffraction analysis, the primary precipitate was H _x RuO ₂ , and as a result of confirming the amount of NO ₃ ^- and NO ₂ ^- remaining in the supernatant using ultraviolet visible light spectroscopy, the conversion rate of sodium nitrate was 99.9%. The supernatant was treated with a sulfuric acid solution and a secondary solvent was added to obtain a secondary precipitate due to the difference in solubility. As a result of X-ray diffraction analysis, crystal phases of Na ₂ SO ₄ and (NH ₄ ) ₂ SO ₄ were mixed. confirmed that there is When sodium nitrate is used as the metal nitrate, the resulting NaOH does not precipitate and remains dissolved in water, and Na ₂ SO ₄ can be obtained by treating it with a sulfuric acid solution. That is, the conversion rate of the sodium nitrate can be confirmed through UV-vis spectroscopy.

<Example 9>

A hydrogenation reaction was performed in the same manner as in Example 8, except that the reaction was performed at a hydrogen pressure of 0.5 MPa. As a result of X-ray diffraction analysis, the primary precipitate was H _x RuO ₂ , and as a result of confirming the supernatant using UV-visible spectroscopy, the conversion rate of sodium nitrate was 93.7%. The supernatant was treated with sulfuric acid solution, and a secondary solvent was added to obtain a secondary precipitate due to the difference in solubility. As a result of X-ray diffraction analysis, crystal phases of Na ₂ SO ₄ and (NH ₄ ) ₂ SO ₄ were mixed. confirmed that it is.

<Example 10>

A hydrogenation reaction was performed in the same manner as in Example 8, except that the reaction was performed at 20° C. for 10 hours. The primary precipitate was H _x RuO ₂ , and as a result of checking the supernatant using UV-visible spectroscopy, the conversion rate of sodium nitrate was 94.0%. The supernatant was treated with a sulfuric acid solution, and a secondary solvent was added to obtain a secondary precipitate due to the difference in solubility. As a result of X-ray diffraction analysis, crystal phases of Na ₂ SO ₄ and (NH ₄ ) ₂ SO ₄ were mixed. confirmed that there is

<Example 11>

The hydrogenation reaction was carried out in the same manner as in Example 1, except that 0.138 g (2 mmol) of sodium nitrite (NaNO ₂ ) was used as the metal nitrite. As a result of X-ray diffraction analysis, the primary precipitate was H _x RuO ₂ , and as a result of confirming the supernatant using ultraviolet visible light spectroscopy, the conversion rate of sodium nitrite was 86.8%. The supernatant was treated with a sulfuric acid solution and a secondary solvent was added to obtain a secondary precipitate due to the difference in solubility. As a result of X-ray diffraction analysis, crystal phases of Na ₂ SO ₄ and (NH ₄ ) ₂ SO ₄ were mixed. confirmed that there is In the case of using sodium nitrite as the metal nitrate, NaOH produced as in the case of using sodium nitrate does not precipitate and remains dissolved in water, and Na ₂ SO ₄ can be obtained by treating it with a sulfuric acid solution. The conversion rate of the sodium nitrite can be confirmed through UV-vis spectroscopy.

Hydrogenation reaction test results

Example Nitrate/Nitrite density
[M] ^a NO _x
[mmol] P _H2
[MPa] temperature
[℃] hour
[h] NO ₃ ^-
[%] NO ₂ ^-
[%] conversion rate
[%] ^b NH ₄ ⁺
yield
[%] ^c One Ca(NO ₃ ) ₂ 4H ₂ O 1.0 2.0 1.0 100 One 0.38 0.1 99.5 74.2 2 Ca(NO ₃ ) ₂ 4H ₂ O 1.0 2.0 2.0 100 One 0.54 0.13 99.3 86.4 3 Ca(NO ₃ ) ₂ 4H ₂ O 1.0 2.0 0.5 100 One 55.3 0.32 44.4 - 4 Ca(NO ₃ ) ₂ 4H ₂ O 0.5 1.0 1.0 100 0.5 0.39 0.01 99.6 87.8 5 Ca(NO ₃ ) ₂ 4H ₂ O 0.5 2.0 1.0 60 4 0.53 0.12 99.4 80.2 6 Ca(NO ₃ ) ₂ 4H ₂ O 0.5 2.0 1.0 80 1.5 3.65 0.32 96.0 77.2 7 Zn(NO ₃ ) ₂ 6H ₂ O 1.0 2.0 1.0 100 One 50.8 0.4 49.4 - 8 NaNO ₃ 1.0 2.0 1.0 100 One 0.70 0.22 99.9 - 9 NaNO ₃ 1.0 2.0 0.5 100 One 6.26 0.31 93.7 - 10 NaNO ₃ 1.0 2.0 0.5 20 10 6.02 1.36 94.0 - 11 NaNO ₂ 1.0 2.0 1.0 100 One - 13.3 86.8 -

Table 1 shows the catalytic activity of converting a metal nitrate (Examples 1 to 10) or a metal nitrite (Example 11) into an ammonium salt through a hydrogenation reaction under a monoclinic ruthenium oxide (H _x RuO ₂ ) catalyst. it is shown Concentration [M] ^a is the concentration of NO _x contained in nitrate/nitrite before hydrogenation, and conversion rate [%] ^b measures NO ₃ ^- or NO ₂ ^- remaining in the supernatant after hydrogenation using UV-visible spectroscopy and the yield of NH ₄ ⁺ [%] ^c is the yield of nitrate calculated through the weight of the obtained ammonium sulfate.

The above description of the present application is for illustrative purposes, and those skilled in the art will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present application. .

Claims (14)

As a catalyst comprising a monoclinic ruthenium oxide represented by the following formula (I),
A catalyst used in the production of ammonia through hydrogenation of nitrogen oxides:
[Formula I]
H _x RuO ₂ ;
In Formula I, 0<x≤4.
According to claim 1,
The monoclinic ruthenium oxide has an incident angle (2θ) of 18.38°<2θ<18.42°, 25.45°<2θ<25.51°, 26.26°<2θ<26.32°, 33.45°<2θ<26.32°, 33.45°< 2θ <33.51°, 35.28°< 2θ <35.34°, 36.24°< 2θ <36.30°, 37.32°< 2θ <37.38°, 39.55°< 2θ <39.61°, 40.61°< 2θ <40.67°, 41.46°< 2θ < 41.52°, 49.17°< 2θ <49.23°, 52.31°< 2θ <52.37°, 54.03°< 2θ <54.09°, 54.70°< 2θ <54.76°, 55.95°< 2θ <56.01°, 59.97°< 2θ <60.03° , 60.40°< 2θ <60.46°, 61.92°< 2θ <61.98°, 63.94°< 2θ <64.00°, 65.79°< 2θ <65.85° and 69.13°< 2θ <69.19° where diffraction peaks are observed phosphorus, catalyst.
According to claim 1,
The monoclinic ruthenium oxide has a structure of monoclinic space group P2 ₁ /c, C2/m, P2/c, C2/c, P2/m, or P2 ₁ /m.
According to claim 1,
In the monoclinic structure,
5 Å ≤ a ≤ 6 Å, 5 Å ≤ b ≤ 6 Å and 5 Å ≤ c ≤ 6 Å,
The beta (β) angle is 110 ° to 120 °, the catalyst.
According to claim 1,
In the monoclinic structure,
wherein a=5.3533 Å, b=5.0770 Å, c=5.3532 Å, and the beta (β) angle is 115.9074°.
Obtaining ammonia by hydrogenation reaction by supplying hydrogen gas to the catalyst and nitrate according to any one of claims 1 to 5
Including, ammonia production method.
According to claim 6,
The nitrate is a metal nitrate, ammonia production method.
According to claim 6,
The concentration of the nitrate is 0.1 M to 5 M, ammonia production method.
According to claim 6,
Based on 100 parts by weight of the nitrate, the catalyst is 0.1 parts by weight to 10 parts by weight, ammonia production method.
According to claim 6,
The supply pressure of the hydrogen gas is 0.1 MPa to 10 MPa, ammonia production method.
According to claim 6,
The supply pressure of the hydrogen gas is 0.5 MPa to 1.5 MPa, ammonia production method.
According to claim 6,
The hydrogenation reaction is carried out in the temperature range of 20 ℃ to 200 ℃, ammonia production method.
According to claim 6,
The conversion rate of the nitrate is 40% or more, ammonia production method.
According to claim 6,
A method for producing ammonia, further comprising obtaining an ammonium salt by adding an inorganic acid to the mixture after the hydrogenation reaction.

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