Method for producing calcium hydroxide from limestone or calcium compound

Abstract

The present application relates to a method for producing calcium hydroxide from limestone or a calcium compound. The method for producing calcium hydroxide according to embodiments of the present application can implement an eco-friendly process that does not discharge carbon dioxide compared to a conventional method. Also, the method can implement an economical process with low energy costs since the method does not employ a high-temperature heat treatment process for producing calcium oxide (CaO) and thus is performed at a low temperature compared to a conventional method for producing calcium hydroxide.

Description

Method for producing calcium hydroxide from limestone or calcium compounds

[0001] The present invention relates to a method for producing calcium hydroxide from limestone or a calcium compound.

[0002] Calcium hydroxide (Ca(OH)2) is a strong alkaline substance. It is an environmentally friendly and harmless element, so it is widely used across various industries such as construction, steelmaking, water treatment, agriculture, and food. For example, calcium hydroxide is used to safely treat industrial waste. Since direct landfill disposal of acidic industrial waste can cause fatal environmental disasters by contaminating the soil, calcium hydroxide is used as a neutralizing agent in the treatment of large amounts of wastewater generated in steelmaking and metal refining processes. Recently, it has been used as a neutralizing agent in the treatment of highly acidic wastewater containing phosphoric acid (H3PO4) or hydrofluoric acid (HF) in semiconductor process wastewater.

[0003] Calcium hydroxide with low purity is used as a neutralizing agent for acid wastewater, an inorganic coagulant in water and sewage treatment, and a purifying agent in improving the water quality of lakes and rivers. Meanwhile, calcium hydroxide fine particles with a purity of 90% or higher are used to reduce air pollution and reduce sulfur oxides (SO ), which are environmental pollutants. x ), nitrogen oxides (NO x ), plays a role in significantly reducing pollutants such as carbon monoxide. High-grade calcium hydroxide with a purity of 95% or more and good color and powder shape is used as a food additive; or for sugar refining or raw sugar refining.

[0004] The conventional method for manufacturing calcium hydroxide is a relatively easy process of reacting calcium oxide (CaO) with water, as shown in the following reaction formula 1. However, since calcium oxide, the raw material for manufacturing calcium hydroxide, is manufactured by heat-treating limestone (CaCO3) at a high temperature of 900°C or higher, the energy cost is high. In addition, the conventional method for manufacturing calcium hydroxide has the problem of high greenhouse gas emissions because it is a process that emits a large amount of carbon dioxide, as shown in the following reaction formula 2.

[0005] [Reaction Formula 1]

[0006] CaO + H2O → Ca(OH)2

[0007] [Reaction Formula 2]

[0008] CaCO3→ CaO + CO2

[0009] Furthermore, limestone, the raw material for calcium hydroxide, contains impurities other than calcium carbonate (CaCO3). Therefore, conventional calcium hydroxide manufacturing processes, which involve crushing limestone and using it directly without separation, yield low-purity calcium oxide containing impurities. Even when water is added during calcium hydroxide production, these impurities remain as byproducts. Therefore, an additional process to remove these impurities is essential for producing high-quality calcium hydroxide.

[0010] Therefore, there is a need to develop an economical and environmentally friendly low-temperature manufacturing process technology that can produce high-purity calcium hydroxide without going through a high-temperature heat treatment process.

[0011] [Prior Art Literature]

[0012] (Patent Document 1) Republic of Korea Patent Publication No. 10-2013-7025562.

[0013] The present invention provides a method for producing calcium hydroxide from limestone or a calcium compound.

[0014] However, the problems that the present invention seeks to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0015] The first aspect of the present invention provides a method for producing calcium hydroxide, comprising catalytically reacting limestone or a calcium compound; nitric acid; and hydrogen to obtain calcium hydroxide and an ammonia compound.

[0016] The second aspect of the present invention provides a ruthenium oxide catalyst having a monoclinic structure, represented by the following chemical formula Ⅰ, which is used in the method for producing calcium hydroxide according to the first aspect:

[0017] [Chemical Formula I]

[0018] H x RuO2;

[0019] In the above chemical formula Ⅰ, 0< x ≤4.

[0020] The method for producing calcium hydroxide according to the embodiments of the present invention does not require a high-temperature heat treatment process to produce calcium oxide (CaO), and thus can be performed at a lower temperature compared to conventional calcium hydroxide production methods, thereby implementing an economical process with lower energy costs.

[0021] The method for producing calcium hydroxide according to the embodiments of the present invention can implement an environmentally friendly process that does not emit carbon dioxide compared to conventional methods.

[0022] The method for producing calcium hydroxide according to the embodiments of the present invention may produce expensive ammonia compounds as a side effect.

[0023] The yield ratio of calcium hydroxide that can be obtained using the method for producing calcium hydroxide according to the embodiments of the present invention may be about 60% or more, about 70% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 96% or more, or about 97% or more.

[0024] The catalyst used in the method for producing calcium hydroxide according to the embodiments of the present invention is economical because it does not melt or lose its structure during the reaction, so the reaction can be performed for a long time, and can be separated and recovered after the reaction and reused.

[0025] The catalyst used in the method for producing calcium hydroxide according to the embodiments of the present invention has excellent reaction activity and can produce calcium hydroxide in a high yield.

[0026] Figure 1 is a schematic diagram of a reaction in which nitric acid and hydrogen containing calcium carbonate (CaCO3) are catalytically reacted to obtain calcium hydroxide (Ca(OH)2) and an ammonia compound, in one embodiment of the present invention.

[0027] Figure 2 is a powder X-ray diffraction (PXRD) graph of Ca(OH)2 manufactured according to Example 1 of the present invention.

[0028] Figure 3 is a powder X-ray diffraction analysis graph of NH4NO3 manufactured according to Example 1 of the present invention.

[0029] Figure 4 is a graph of powder X-ray diffraction analysis of limestone, a reactant of Example 5 of the present invention.

[0030] Figure 5 is a powder X-ray diffraction analysis graph of Ca(OH)2 manufactured according to Example 5 of the present invention.

[0031] Hereinafter, with reference to the attached drawings, implementation examples and embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the implementation examples and embodiments described herein. In addition, in the drawings, parts irrelevant to the description have been omitted to clearly explain the present invention, and similar parts have been designated with similar drawing reference numerals throughout the specification.

[0032] Throughout this specification, when a part is said to be "connected" to another part, this includes not only cases where it is "directly connected" but also cases where it is "electrically connected" with another element in between.

[0033] Throughout this specification, when it is said that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the two elements.

[0034] Throughout this specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0035] The terms "about," "substantially," and the like used in this specification are used in a meaning that is at or close to the numerical value when manufacturing and material tolerances inherent in the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which exact or absolute values ​​are mentioned to aid understanding of the present application.

[0036] The terms “step of ~” or “step of ~” as used throughout this specification do not mean “step for ~.”

[0037] Throughout this specification, the term "combination(s) thereof" included in the expressions in the Makushi format means one or more mixtures or combinations selected from the group consisting of the components described in the expressions in the Makushi format, and means including one or more selected from the group consisting of said components.

[0038] Throughout this specification, references to “A and / or B” mean “A or B, or A and B.”

[0039] Below, the implementation examples of the present invention are described in detail, but the present invention may not be limited thereto.

[0040] The first aspect of the present invention provides a method for producing calcium hydroxide, comprising catalytically reacting limestone or a calcium compound; nitric acid; and hydrogen to obtain calcium hydroxide and an ammonia compound.

[0041] In one embodiment of the present invention, the limestone is an ore mainly composed of calcium carbonate (CaCO3), and may include other components, and the scope of application of the present invention may be expanded. For example, the limestone may include marble, calcite, feldspar, limestone, chalk, glacierite, seashells, eggshells, and coral, all of which contain calcium carbonate.

[0042] In one embodiment of the present invention, the calcium compound may include one or more selected from process by-products, wastes, and salts containing calcium.

[0043] In one embodiment of the present invention, the process by-product or the waste may include one or more selected from slag and waste concrete.

[0044] In one embodiment of the present invention, as far as the present invention can be applied, the salt means a salt containing calcium, and may not be limited thereto. In one embodiment of the present invention, the salt may include one or more selected from chlorides, oxides, sulfates, carbonates, nitrates, phosphates, sulfates, silicates, and hydrates thereof, including calcium, and may be, as non-limiting examples, chlorides (e.g., CaCl2), nitrates (e.g., Ca(NO3)2), oxides (e.g., CaO), silicates (e.g., calcium silicate), or sulfur oxides (e.g., CaSO4).

[0045] In one embodiment of the present invention, the concentration of the nitric acid may be from about 0.1 M to about 16 M, but may not be limited thereto. In one embodiment of the present invention, the concentration of the nitric acid may be from about 0.1 M to about 16 M, from about 0.1 M to about 14 M, from about 0.1 M to about 12 M, from about 0.1 M to about 10 M, from about 0.1 M to about 8 M, from about 0.1 M to about 6 M, from about 0.1 M to about 5 M, from about 0.1 M to about 4 M, from about 0.1 M to about 3 M, from about 0.1 M to about 2 M, from about 0.1 M to about 1 M, about 1 M to about 16 M, about 1 M to about 14 M, about 1 M to about 12 M, about 1 M to about 10 M, about 1 M to about 8 M, about 1 M to about 6 M, about 1 M to about 5 M, about 1 M to about 4 M, about 1 M to about 3 M, about 1 M to about 2 M, about 2 M to about 16 M, about 2 M to about 14 M, about 2 M to about 12 M, about 2 M to about 10 M, about 2 M to about 8 M, about 2 M to about 6 M, about 2 M to about 5 M, about 2 M to about 4 M, about 2 M to about 3 M, about 3 M to about 16 M, about 3 M to about 14 M, about 3 M to about 12 M, about 3 M to about 10 M, about 3 M to about 8 M, about 3 M to about 6 M, about 3 M to about 5 M, about 3 M to about 4 M, about 4 M to about 16 M, about 4 M to about 14 M, about 4 M to about 12 M, about 4 M to about 10 M, about 4 M to about 8 M, about 4 M to about 6 M, about 4 M to about 5 M, about 5 M to about 16 M, about 5 M to about 14 M, about 5 M to about 12 M, about 5 M to about 10 M, about 5 M to about 8 M, about 5 M to about 6 M, about 6 M to about 16 M, about 6 M to about 14 M, about 6 M to about 10 M, about 6 M to about 8 M, about 6 M to about 7 M, about 8 M to about 16 M, about 8 M to about 14 M, about 8 M to about 12 M, about 8 M to about 10 M, about 10 M to about 16 M, about 10 M to about 14 M, about 10 M to about 12 M, about 12 M to about 16 M, about 12 M to about 14 M, or about 14 M to about 16 M. In one embodiment of the present invention, the concentration of the nitric acid is about 0.When it is less than 1 M, the production rate of calcium hydroxide slows down, and when the concentration of the nitric acid exceeds about 16 M, the yield rate of calcium hydroxide may decrease due to high acidity.

[0046] In one embodiment of the present invention, the catalyst may be selected from a metal, alloy or oxide including at least one selected from titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), indium (In), tin (Sn), phosphorus (P), aluminum (Al), silicon (Si), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au).

[0047] In one embodiment of the present invention, the catalyst may include a ruthenium oxide represented by the following chemical formula Ⅰ:

[0048] [Chemical Formula I]

[0049] H x RuO 2;

[0050] In the above chemical formula Ⅰ, 0< x ≤4.

[0051] In one embodiment of the present invention, when the diameter of the catalyst particles is about 10 nm or less, the reaction activity may be enhanced, but may not be limited thereto. In one embodiment of the present invention, the diameter of the catalyst particles may be about 10 nm or less, about 8 nm or less, about 6 nm or less, or about 4 nm or less.

[0052] In one embodiment of the present invention, the catalyst does not melt or its structure collapse during the reaction, so the reaction can be performed for a long time.

[0053] In one embodiment of the present invention, the catalyst can be separated and recovered after the reaction is completed and reused.

[0054] In one embodiment of the present invention, it is preferable in terms of activity and / or stability to use a catalyst including ruthenium oxide represented by the chemical formula I for the reaction, but another metal or metal salt may be additionally used as an auxiliary catalyst.

[0055] In one embodiment of the present invention, the catalyst may be used in an amount of about 0.1 part by weight to about 10 parts by weight relative to 100 parts by weight of the limestone or the calcium compound. In one embodiment of the present invention, the catalyst may be used in an amount of about 0.1 part by weight to about 10 parts by weight, about 0.1 part by weight to about 9 parts by weight, about 0.1 part by weight to about 8 parts by weight, about 0.1 part by weight to about 7 parts by weight, about 0.1 part by weight to about 6 parts by weight, about 0.1 part by weight to about 5 parts by weight, about 0.1 part by weight to about 4 parts by weight, about 0.1 part by weight to about 3 parts by weight, about 0.1 part by weight to about 2 parts by weight, or about 0.1 part by weight to about 1 part 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 part by weight to about 7 parts by weight, about 1 part by weight to about 6 parts by weight, about 1 part by weight to about 5 parts by weight, about 1 part by weight to about 4 parts by weight, about 1 part by weight to about 3 parts by weight, about 1 part by weight to about 2 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 to about 7 parts by weight, about 2 parts by weight to about 6 parts by weight, about 2 parts by weight to about 5 parts by weight, about 2 parts by weight to about 4 parts by weight, about 2 parts by weight to about 3 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 to about 7 parts by weight, about 3 parts by weight to about 6 parts by weight, about 3 parts by weight to about 5 parts by weight, about 3 parts by weight to about 4 parts by weight, about 4 parts by weight to about 10 parts by weight, about 4 parts by weight to about 9 parts by weight, about 4 parts by weight to about 8 parts by weight, about 4 parts by weight to about 7 parts by weight, about 4 parts by weight to about 6 parts by weight, about 4 parts by weight to about 5 parts by weight, about 5 parts by weight to about 10 parts by weight, about 5 parts by weight to about 9 parts by weight, about 5 parts by weight to about 8 parts by weight, about 5 parts by weight to about 7 parts by weight, about 5 parts by weight to about 6 parts by weight, about 6 parts by weight to about 10 parts by weight, about 6 parts by weight to about 9 parts by weight, about 6 parts by weight to about 8 parts by weight, about 6 parts by weight to about 7 parts by weight, about 7 It may be used in an amount of about 10 parts by weight, about 7 parts by weight to about 9 parts by weight, about 7 parts by weight to about 8 parts by weight, about 8 parts by weight to about 10 parts by weight, about 8 parts by weight to about 9 parts by weight, or about 9 parts by weight to about 10 parts by weight.In one embodiment of the present invention, when the catalyst is used in an amount of about 0.1 parts by weight or less with respect to 100 parts by weight of the limestone or the calcium compound, the reaction time of the hydrogenation reaction may be prolonged and / or the reaction may not be completed, and when the catalyst is used in an amount of about 10 parts by weight or more with respect to 100 parts by weight of the limestone or the calcium compound, the speed of the hydrogenation reaction may be increased, but the separation efficiency may be reduced in the process of separating the product and the catalyst.

[0056] In one embodiment of the present invention, the catalytic reaction may be performed at a temperature range of about 20°C to about 200°C. In one embodiment of the present invention, the catalytic reaction is carried out at a temperature of about 20°C to about 200°C, about 20°C to about 190°C, about 20°C to about 180°C, about 20°C to about 170°C, about 20°C to about 160°C, about 20°C to about 150°C, about 20°C to about 140°C, about 20°C to about 130°C, about 30°C to about 200°C, about 30°C to about 190°C, about 30°C to about 180°C, about 30°C to about 170°C, about 30°C to about 160°C, about 30°C to about 150°C, about 30°C to about 140°C, about 30°C to about 130°C, about 40°C to about 200°C, about 40°C to about The catalytic reaction may be performed at a temperature range of about 190°C, about 40°C to about 180°C, about 40°C to about 170°C, about 40°C to about 160°C, about 40°C to about 150°C, about 40°C to about 140°C, about 40°C to about 130°C, about 50°C to about 200°C, about 50°C to about 190°C, about 50°C to about 180°C, about 50°C to about 170°C, about 50°C to about 160°C, about 50°C to about 150°C, about 50°C to about 140°C, or about 50°C to about 130°C. In one embodiment of the present disclosure, it may be most preferable that the catalytic reaction is performed at a temperature range of about 60°C to about 120°C.

[0057] In one embodiment of the present invention, the catalytic reaction may be performed in a hydrothermal reactor.

[0058] In one embodiment of the present invention, the pressure of the hydrogen may be from about 0.1 MPa to about 10 MPa. In one embodiment of the present invention, the pressure of the hydrogen is about 0.1 MPa to about 10 MPa, about 0.1 MPa to about 9 MPa, about 0.1 MPa to about 8 MPa, about 0.1 MPa to about 7 MPa, about 0.1 MPa to about 6 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 1 MPa to about 10 MPa, about 1 MPa to about 9 MPa, about 1 MPa to about 8 MPa, about 1 MPa to about 7 MPa, about 1 MPa to about 6 MPa, about 1 MPa to about 5 MPa, about 1 MPa to about 4 MPa, about 1 MPa to about 3 MPa, about 1.5 MPa to about 10 MPa, about 1.5 The pressure may be from about 9 MPa to about 9 MPa, from about 1.5 MPa to about 8 MPa, from about 1.5 MPa to about 7 MPa, from about 1.5 MPa to about 6 MPa, from about 1.5 MPa to about 5 MPa, from about 1.5 MPa to about 4 MPa, or from about 1.5 MPa to about 3 MPa. In one embodiment of the present disclosure, when the pressure of the hydrogen is about 0.1 MPa or less, the reaction rate may be very slow, and when the pressure of the hydrogen is about 10 MPa or more, the reaction may not proceed smoothly. In one embodiment of the present disclosure, the pressure of the hydrogen may be most preferably about 2 MPa.

[0059] In one embodiment of the present invention, the calcium hydroxide may be obtained as a precipitate of the solution through filtration, but is not limited thereto. In one embodiment of the present invention, the ammonia may be obtained in the form of an ammonia compound by adding carbon dioxide or an acid to the solution, but is not limited thereto.

[0060] In one embodiment of the present invention, after the production reaction of calcium hydroxide, the method may further comprise separating the catalyst. In one embodiment of the present invention, after the hydrogenation reaction, the method may further comprise separating a precipitate containing the catalyst and calcium hydroxide.

[0061] In one embodiment of the present invention, the method may further include adding an inorganic acid to the product of the hydrogenation reaction to obtain an ammonium salt. In one embodiment of the present invention, the inorganic acid may be, but is not limited to, sulfuric acid, nitric acid, hydrochloric acid, or acetic acid. In one embodiment of the present invention, the ammonium salt may be ammonium sulfate ((NH4)2SO4), ammonium hydrogen sulfate (NH4HSO4), ammonium nitrate (NH4NO3), ammonium hydrochloride (NH4Cl), or ammonium acetate (NH4CH3CO2), and the ammonium salt may vary depending on the type of the inorganic acid. Here, the yield of ammonium ions can be calculated through the weight of the ammonium salt obtained by additionally adding an inorganic acid, but this may be an additional value experimentally confirmed in the process of obtaining an ammonium salt for actual separation and use of ammonium ions after generating ammonia from nitrate ions.

[0062] The second aspect of the present invention provides a ruthenium oxide catalyst having a monoclinic structure, represented by the following chemical formula Ⅰ, which is used in the method for producing calcium hydroxide according to the first aspect:

[0063] [Chemical Formula I]

[0064] H x RuO2;

[0065] In the above chemical formula Ⅰ, 0< x ≤4.

[0066] Detailed explanations of parts that overlap with the first aspect of the present application have been omitted, but the contents described in the first aspect of the present application may be equally applied even if the explanation is omitted in the second aspect of the present application.

[0067] In one embodiment of the present invention, in the chemical formula I, x (atomic ratio of hydrogen) is greater than 0 and less than 4, greater than 0 and about 3.5 and less than 3, greater than 0 and about 2.5 and less than 2, greater than 0 and about 1.5 and less than 1, greater than 0 and about 1.2 and less than 1, about 0.1 to about 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 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 disclosure, in the chemical formula Ⅰ, x may be about 0.4 to about 1.2.

[0068] In one embodiment of the present invention, in the chemical formula I, the closer x (atomic ratio of hydrogen) is to about 1, the easier it is to produce the monoclinic ruthenium oxide. Specifically, in the chemical formula I, when the ratio of hydrogen is from about 0.6 to about 1.4, the monoclinic ruthenium oxide may be easier to produce. Here, when x is 0 in the chemical formula I, a structural transition to a tetragonal rutile ruthenium oxide may occur, so it is preferable to maintain the hydrogen content.

[0069] In one embodiment of the present invention, the atomic ratio of hydrogen included in the chemical formula I can be calculated by thermo-gravimetric analysis (TGA). Specifically, in the analysis using the thermo-gravimetric analysis, the weight change can be measured while placing a solid sample in a platinum container and increasing the temperature. The monoclinic ruthenium oxide (H x All hydrogen contained in RuO2 is removed and converted into tetragonal ruthenium oxide (RuO2). The amount of hydrogen can be quantitatively analyzed from the weight change according to temperature.

[0070] In one embodiment of the present invention, the ruthenium oxide catalyst has an incident angle (2θ) determined by X-ray powder diffraction measurement (Cu Kα line) of 18.38°< 2θ <18.42°, 25.45°< 2θ <25.51°, 26.26°< 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 Diffraction peaks may be observed at each position of <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°. In one embodiment of the present invention, the ruthenium oxide catalyst may have diffraction peaks observed at positions where the incident angles (2θ) determined by X-ray powder diffraction measurement (Cu Kα line) are 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°.

[0071] In one embodiment of the present invention, the ruthenium oxide catalyst may have a structure of a monoclinic space group P21 / c, C2 / m, P2 / c, C2 / c, P2 / m, or P21 / m, but may not be limited thereto.

[0072] In one embodiment of the present invention, the unit cell of the monoclinic crystal structure of the ruthenium oxide catalyst can be defined by lattice constants a to c and edge angle beta (β).

[0073] In one embodiment of the present invention, 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 may be about 110° to about 120°. For example, a to c are each 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, about 5.1 Å to about 5.8 Å, about 5.2 Å to about 5.8 Å, about 5.3 Å to about 5.8 Å, about 5 Å to about 5.6 Å, about 5.1 Å to about 5.6 Å, about 5.2 Å to about 5.6 Å, about 5.3 Å to about 5.6 Å, about 5 Å to about 5.4 Å, about 5.1 Å to about 5.4 Å, about 5.2 Å to about 5.4 Å, about 5.3 Å to about 5.4 Å or about 5.35 Å to about 5.4 Å, wherein b may be 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, and wherein 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 It could be 116°.

[0074] In one embodiment of the present invention, in the monoclinic structure, a=5.3533 Å, b=5.0770 Å, c=5.3532 Å, and the beta (β) angle may be 115.9074°, but may not be limited thereto.

[0075] Hereinafter, the present invention will be described in more detail using examples. However, the following examples are provided only to help understand the present invention, and the contents of the present invention are not limited to the following examples.

[0076] Example 1

[0077] 0.2 g of CaCO3 (2.00 mmol), 20 mg of H x RuO2 (0.15 mmol) and 2.0 M HNO3 (2 mL) were placed in a hydrothermal reactor, the interior of the hydrothermal reactor was filled with a hydrogen pressure of 2.0 MPa, and the reaction was carried out at 100°C for 10 hours. After the reaction was completed, the hydrothermal reactor was cooled to room temperature, and the generated precipitate and residual solution were separated.

[0078] After drying, the above precipitate was identified as calcium hydroxide (Ca(OH)2) through X-ray powder diffraction analysis (Fig. 2). The mass of the obtained Ca(OH)2 was 0.145 g (1.96 mmol), and the yield of Ca(OH)2 calculated based on CaCO3 was 97.9%.

[0079] The residual solution after the reaction was analyzed by ultraviolet-visible spectroscopy and showed that nitrogen oxide ions (NO3 - and NO2 -) was not confirmed, and through this, it was confirmed that all nitrate ions were reduced to ammonia or nitrogen. Nitric acid was added to the residual solution and evaporated to obtain crystals, which were confirmed to be ammonium nitrate (NH4NO3) through X-ray powder diffraction (Fig. 3). The mass of the obtained NH4NO3 was 0.301 g (3.76 mmol), and the yield calculated based on HNO3 was 94.1%.

[0080] Example 2

[0081] The hydrogenation reaction was performed in the same manner as in Example 1, except that the reaction was performed under a hydrogen pressure of 5.0 MPa. The precipitate formed after the reaction was dried and confirmed to be Ca(OH)2 by X-ray powder diffraction analysis. The mass of the obtained Ca(OH)2 was 0.139 g (1.88 mmol), and the yield of Ca(OH)2 calculated based on CaCO3 was 93.8%.

[0082] After the reaction, nitric acid was added to the residual solution and evaporated to obtain crystals, which were confirmed to be ammonium nitrate (NH4NO3) through X-ray powder diffraction. The mass of the obtained NH4NO3 was 0.313 g (3.91 mmol), and the yield calculated based on HNO3 was 97.8%.

[0083] Example 3

[0084] A hydrogenation reaction was performed in the same manner as in Example 1, except that 2 mL of distilled water was additionally added and the reaction was carried out. The precipitate formed after the reaction was dried and confirmed to be Ca(OH)2 through X-ray powder diffraction analysis. The mass of the obtained Ca(OH)2 was 0.125 g (1.69 mmol), and the yield of Ca(OH)2 calculated based on CaCO3 was 84.3%.

[0085] After the reaction, nitric acid was added to the residual solution and evaporated to obtain crystals, which were confirmed to be ammonium nitrate (NH4NO3) through X-ray powder diffraction. The mass of the obtained NH4NO3 was 0.294 g (3.67 mmol), and the yield calculated based on HNO3 was 91.9%.

[0086] Example 4

[0087] A hydrogenation reaction was performed in the same manner as in Example 1, except that the reaction was performed at 60°C. The precipitate formed after the reaction was dried and confirmed to be Ca(OH)2 through X-ray powder diffraction analysis. The mass of the obtained Ca(OH)2 was 0.087 g (1.17 mmol), and the yield of Ca(OH)2 calculated based on CaCO3 was 58.7%.

[0088] After the reaction, nitric acid was added to the residual solution and evaporated to obtain crystals, which were confirmed to be ammonium nitrate (NH4NO3) through X-ray powder diffraction. The mass of the obtained NH4NO3 was 0.183 g (2.29 mmol), and the yield calculated based on HNO3 was 57.2%.

[0089] Example 5

[0090] A hydrogenation reaction was performed in the same manner as in Example 1, except that 0.2 g of commercial limestone (Fig. 4) was dissolved in nitric acid instead of calcium carbonate as a reactant, and the undissolved solid was separated and used for the reaction. The precipitate formed after the reaction was dried and confirmed to be Ca(OH)2 by X-ray powder diffraction analysis (Fig. 5). The mass of the obtained Ca(OH)2 is 0.107 g (1.44 mmol).

[0091] Example 6

[0092] The reaction was carried out in the same manner as in Example 1, except that ruthenium powder (7.6 mg, 0.075 mmol) was used as a catalyst. After the reaction was completed, the yield of Ca(OH)2 obtained was less than 5%, and a very small amount was obtained.

[0093] Example 7

[0094] The reaction was carried out in the same manner as in Example 1, except that platinum powder (14.6 mg, 0.075 mmol) was used as a catalyst. After the reaction was completed, the mass of the obtained Ca(OH)2 was 0.115 g (1.55 mmol), and the yield of Ca(OH)2 calculated based on CaCO3 was 77.6%. The mass of the obtained NH4NO3 was 0.232 g (2.88 mmol), and the yield calculated based on HNO3 was 72.5%.

[0095] Example 8

[0096] The reaction was carried out in the same manner as in Example 1, except that palladium powder (8.0 mg, 0.075 mmol) was used as a catalyst. After the reaction was completed, the mass of the obtained Ca(OH)2 was 0.120 g (1.62 mmol), and the yield of Ca(OH)2 calculated based on CaCO3 was 81.0%. The mass of the obtained NH4NO3 was 0.256 g (3.20 mmol), and the yield calculated based on HNO3 was 80.0%.

[0097] Example 9

[0098] The reaction was carried out in the same manner as in Example 1, except that nickel powder (7.1 mg, 0.075 mmol) was used as a catalyst. After the reaction was completed, the yield of Ca(OH)2 obtained was less than 5%, and a very small amount was obtained.

[0099] The above description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that modifications to other specific forms can be made without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, components described as single may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

Claims

1. A process for producing calcium hydroxide and an ammonia compound by catalytically reacting limestone or a calcium compound; nitric acid; and hydrogen. Method for producing calcium hydroxide.

2. In paragraph 1, A method for producing calcium hydroxide, wherein the limestone includes marble, calcite, feldspar, limestone, chalk, glacierite, seashell, egg shell, and coral containing calcium carbonate.

3. In paragraph 1, A method for producing calcium hydroxide, wherein the calcium compound comprises at least one selected from process by-products, waste products and salts containing calcium.

4. In paragraph 3, The above process by-product or the above waste comprises at least one selected from slag and waste concrete, A method for producing calcium hydroxide, wherein the salt comprises at least one selected from chlorides, oxides, sulfates, carbonates, nitrates, phosphates, sulfates, silicates, and hydrates thereof, containing calcium.

5. In paragraph 1, A method for producing calcium hydroxide, wherein the catalyst is selected from a metal, alloy or oxide comprising at least one selected from titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), indium (In), tin (Sn), phosphorus (P), aluminum (Al), silicon (Si), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au).

6. In paragraph 5, A method for producing calcium hydroxide, wherein the catalyst comprises ruthenium oxide represented by the following chemical formula Ⅰ: [Chemical Formula I] H x RuO2; In the above chemical formula Ⅰ, 0< x ≤4.

7. In paragraph 1, A method for producing calcium hydroxide, wherein the catalyst is used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the limestone or the calcium compound.

8. In paragraph 1, A method for producing calcium hydroxide, wherein the above catalytic reaction is performed at a temperature range of 20°C to 200°C.

9. In paragraph 1, A method for producing calcium hydroxide, wherein the above catalytic reaction is performed in a hydrothermal reactor.

10. In paragraph 1, A method for producing calcium hydroxide, wherein the pressure of the hydrogen is 0.1 MPa to 10 MPa.

11. In paragraph 1, A method for producing calcium hydroxide, wherein the concentration of the nitric acid is 0.1 M to 16 M.

12. In paragraph 1, A method for producing calcium hydroxide, wherein the above catalytic reaction is performed under solution conditions containing a solvent.

13. In paragraph 12, A method for producing calcium hydroxide, wherein the solvent is selected from distilled water, methanol, and ethanol.

14. It is represented by the following chemical formula Ⅰ, As a ruthenium oxide catalyst having a monoclinic structure, Ruthenium oxide catalyst used in the method for producing calcium hydroxide according to Article 1: [Chemical Formula I] H x RuO2; In the above chemical formula Ⅰ, 0< x ≤4.

15. In paragraph 14, The above ruthenium oxide catalyst was measured by X-ray powder diffraction (Cu Kα line) and the incident angle (2θ) was 18.38°< 2θ <18.42°, 25.45°< 2θ <25.51°, 26.26°< 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°, A ruthenium oxide catalyst, wherein diffraction peaks are observed at each position of 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°.

16. In paragraph 14, The above ruthenium oxide catalyst is a ruthenium oxide catalyst having a structure of a monoclinic space group P21 / c, C2 / m, P2 / c, C2 / c, P2 / m, or P21 / m.

17. In paragraph 14, In the above monoclinic structure, 5 Å≤ a ≤6 Å, 5 Å≤ b ≤6 Å, and 5 Å≤ c ≤6 Å, A ruthenium oxide catalyst having a beta (β) angle of 110° to 120°.

18. In paragraph 14, In the above monoclinic structure, A ruthenium oxide catalyst having a=5.3533 Å, b=5.0770 Å, c=5.3532 Å, and a beta (β) angle of 115.9074°.

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