A preparation method for efficiently producing calcium oxide using a rare earth-doped catalyst

Abstract

The present invention discloses a method for efficiently producing calcium oxide using a rare earth-doped catalyst. In a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, gypsum and the catalyst are mixed and then heated to 1020-1050°C for decomposition. The decomposition product is purified to produce calcium oxide. The catalyst prepared using the method is added to gypsum and thermally decomposed, significantly promoting the decomposition of calcium sulfate into calcium oxide. This reduces the time required for thermal decomposition and increases the yield of calcium oxide, thereby improving production efficiency and reducing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth doped catalysts for producing calcium oxide, and in particular to a preparation method for efficiently producing calcium oxide by using the rare earth doped catalysts. Background Art

[0002] Quicklime is an inorganic material primarily composed of CaO. The traditional method for preparing quicklime involves calcining raw materials with a high calcium carbonate content, such as limestone and dolomite, at temperatures between 900°C and 1100°C. Although my country has abundant reserves of limestone and other mineral resources, over-exploitation has severely damaged surface vegetation and the ecological environment. Due to the rapid development of industries such as steel, non-ferrous metal smelting, chemicals, and environmental protection in recent years, demand for quicklime in China has rapidly increased. Traditional quicklime production processes not only consume large quantities of limestone and other mineral resources but also inevitably generate significant amounts of carbon dioxide during production. Furthermore, my country is a country with a shortage of sulfur resources. Sulfur reserves far exceed market demand, resulting in a surge in sulfur imports. Calcium sulfate contains abundant calcium and sulfur resources. If calcium sulfate could be decomposed into calcium oxide and sulfur dioxide, the decomposition product, calcium oxide, could be used directly as the main component of quicklime or as a raw material for other calcium-based products. High-concentration sulfur dioxide can be used to produce sulfur-containing byproducts such as sulfur, sulfuric acid, or liquid sulfur dioxide, depending on actual demand. It can not only solve the problem of difficult treatment of desulfurization gypsum in my country, but also utilize it as a resource to produce high-value calcium and sulfur products, reduce the amount of natural mineral resources mined, and alleviate the current shortage of sulfur resources in my country. Summary of the Invention

[0003] To this end, the present invention provides a method for efficiently producing calcium oxide using a rare earth-doped catalyst. In a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, gypsum and the catalyst are mixed, then heated to 1020-1050°C for decomposition, and the decomposition product is purified to prepare calcium oxide. The catalyst is prepared by:

[0004] (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process, stirring is continued for more than 10 minutes after the addition is completed, and then ammonia water is added, the reactor is sealed, heated to 150±5°C and kept warm for more than 5 hours, and then naturally cooled to room temperature after the end of the insulation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at a temperature of 500-550°C to obtain a matrix powder;

[0005] (2) preparing an aqueous solution of cerium trichloride and chloroiridic acid, and preparing an aqueous solution of sodium hydroxide; adding the matrix powder to ethanol, stirring and dispersing it under ultrasonic conditions for more than 20 minutes to obtain a suspension, heating the suspension in a water bath to 75±3°C and keeping it warm, then adding the aqueous solution of cerium trichloride and chloroiridic acid to the suspension under stirring, continuing to stir at a constant temperature of 75±3°C for more than 10 minutes after the addition is completed, then adding the aqueous solution of sodium hydroxide under stirring, stirring at a constant temperature of 75±3°C for more than 1 hour after the addition is completed, then separating the solid and liquid, washing the solid phase with deionized water for more than 3 times, then drying at 90±10°C for more than 30 minutes, and calcining at a temperature of 500-530°C to obtain a doped powder;

[0006] (3) preparing an aqueous solution of glucose, adding the doped powder to the aqueous solution of glucose, stirring and dispersing under ultrasonic conditions for more than 30 minutes to obtain a dispersion, transferring the dispersion into a reactor, sealing the reactor, heating to 180±5°C and keeping the temperature for more than 5 hours, then naturally cooling to room temperature, opening the reactor, separating the solid and the liquid, washing the solid phase with deionized water for more than 3 times, and drying to obtain the catalyst.

[0007] Furthermore, the mixing volume ratio of the hydrogen, carbon dioxide and nitrogen is hydrogen:carbon dioxide:nitrogen=2:18:80.

[0008] Furthermore, the purification method is: first, removing part of the catalyst in the decomposition product by magnetic separation, then adding the magnetically separated powder into water for rinsing, filtering, collecting the filtrate, passing carbon dioxide gas into the filtrate to generate calcium carbonate precipitate, and then calcining at 550°C for more than 2 hours to obtain calcium oxide with higher purity.

[0009] Furthermore, the mass ratio of the gypsum to the catalyst is gypsum:catalyst=100:5-6; and the decomposition time after heating to 1020-1050° C. is 30-40 minutes.

[0010] Furthermore, in the step (1), in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 50-60 g / L, the concentration of nickel dichloride is 20-30 g / L, and the solvent is water.

[0011] Furthermore, in the step (1), the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 6-8 g: 10-15 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%.

[0012] Furthermore, in step (2), in the aqueous solution of cerium trichloride and chloroiridic acid, the concentration of cerium trichloride is 20-30 g / L, the concentration of chloroiridic acid is 5-6 g / L, and the solvent is water; in the aqueous solution of sodium hydroxide, the mass percentage of sodium hydroxide is 10%, and the solvent is water.

[0013] Furthermore, in the step (2), the matrix powder is added to ethanol in a mass ratio of matrix powder: ethanol = 1:50; the cerium trichloride, chloroiridic acid aqueous solution, and sodium hydroxide aqueous solution are added to the suspension in a volume ratio of suspension: cerium trichloride, chloroiridic acid aqueous solution: sodium hydroxide aqueous solution = 100:15-16:8-10.

[0014] Furthermore, in step (3), the mass percentage of glucose in the glucose aqueous solution is 10% to 12%, and the solvent is water; the mass ratio of the doping powder added to the glucose aqueous solution is doping powder: glucose aqueous solution = 1:20.

[0015] The beneficial effects of the present invention are that the catalyst prepared by the method of the present invention is added to gypsum for thermal decomposition, which can significantly promote the decomposition of calcium sulfate into calcium oxide, reduce the time used for thermal decomposition, increase the yield of calcium oxide, help improve production efficiency and reduce costs. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the embodiments.

[0017] Example 1

[0018] A preparation method for efficiently producing calcium oxide using a rare earth-doped catalyst comprises: mixing gypsum and a catalyst in a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, wherein the volume ratio of the hydrogen, carbon dioxide, and nitrogen is hydrogen:carbon dioxide:nitrogen = 2:18:80; and the mass ratio of the gypsum and catalyst is gypsum:catalyst = 100:5; then heating to 1030°C for decomposition for 30 minutes; and purifying the decomposition product to obtain calcium oxide. The purification method comprises: first removing part of the catalyst from the decomposition product through magnetic separation, then adding the magnetically separated powder to water for leaching, filtering, collecting the filtrate, and passing carbon dioxide gas into the filtrate to form a calcium carbonate precipitate, which is then calcined at 550°C for 2 hours to obtain calcium oxide with high purity. The preparation method of the catalyst is as follows:

[0019] (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 50 g / L, the concentration of nickel dichloride is 20 g / L, and the solvent is water; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, and 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process. After the addition is completed, stirring is continued for 10 minutes, and then ammonia water is added, and the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 6 g: 10 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%; the reactor is closed, heated to 150° C. and kept warm for 5 hours, and then naturally cooled to room temperature after the end of the heat preservation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at a temperature of 500-550° C. for 2 hours to obtain a matrix powder;

[0020] (2) preparing an aqueous solution of cerium trichloride and chloroiridic acid, wherein the concentration of cerium trichloride and chloroiridic acid in the aqueous solution is 20 g / L, the concentration of chloroiridic acid is 5 g / L, and the solvent is water; preparing an aqueous solution of sodium hydroxide, wherein the mass percentage of sodium hydroxide in the aqueous solution is 10%, and the solvent is water; adding the matrix powder to ethanol, wherein the mass ratio of the matrix powder to ethanol is 1:50; stirring and dispersing for 20 minutes under ultrasonic conditions to obtain a suspension, heating the suspension to 75°C in a water bath and keeping it warm, and then adding the suspension to the suspension under stirring. Add the aqueous solution of cerium trichloride and chloroiridic acid, continue stirring at a constant temperature of 75° C. for 10 minutes after the addition is completed, and then add the aqueous solution of sodium hydroxide under stirring, and add the aqueous solution of cerium trichloride, chloroiridic acid, and sodium hydroxide to the suspension in a volume ratio of suspension: aqueous solution of cerium trichloride and chloroiridic acid: aqueous solution of sodium hydroxide = 100:15:8; after the addition is completed, stir at a constant temperature of 75° C. for 1 hour, then separate the solid and liquid, wash the solid phase with deionized water 3 times, and then dry at 90° C. for 30 minutes, and calcine at 500° C. for 1 hour to obtain a doped powder;

[0021] (3) preparing an aqueous solution of glucose, wherein the mass percentage of glucose in the aqueous solution of glucose is 10% and the solvent is water; adding the doping powder to the aqueous solution of glucose, wherein the mass ratio of the doping powder to the aqueous solution of glucose is doping powder: aqueous solution of glucose = 1:20; stirring and dispersing the mixture under ultrasonic conditions for 30 minutes to obtain a dispersion, transferring the dispersion into a reactor, sealing the reactor, heating to 180°C and keeping the temperature for 5 hours, then naturally cooling to room temperature, opening the reactor, separating the solid and the liquid, washing the solid phase with deionized water three times, and drying at 60°C for 2 hours to obtain the catalyst.

[0022] Example 2

[0023] A preparation method for efficiently producing calcium oxide using a rare earth-doped catalyst comprises: mixing gypsum and a catalyst in a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, wherein the volume ratio of the hydrogen, carbon dioxide, and nitrogen is hydrogen:carbon dioxide:nitrogen = 2:18:80; and the mass ratio of the gypsum and catalyst is gypsum:catalyst = 100:5; then heating to 1030°C for decomposition for 30 minutes; and purifying the decomposition product to obtain calcium oxide. The purification method comprises: first removing part of the catalyst from the decomposition product through magnetic separation, then adding the magnetically separated powder to water for leaching, filtering, collecting the filtrate, and passing carbon dioxide gas into the filtrate to form a calcium carbonate precipitate, which is then calcined at 550°C for 2 hours to obtain calcium oxide with high purity. The preparation method of the catalyst is as follows:

[0024] (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 55 g / L, the concentration of nickel dichloride is 25 g / L, and the solvent is water; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, and 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process, and the stirring is continued for 10 minutes after the addition is completed, and then ammonia water is added, and the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 7 g: 12 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%; the reactor is closed, heated to 150° C. and kept warm for 5 hours, and then naturally cooled to room temperature after the end of the heat preservation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at 520° C. for 2 hours to obtain a matrix powder;

[0025] (2) preparing an aqueous solution of cerium trichloride and chloroiridic acid, wherein the concentration of cerium trichloride and chloroiridic acid in the aqueous solution is 24 g / L, the concentration of chloroiridic acid is 5 g / L, and the solvent is water; preparing an aqueous solution of sodium hydroxide, wherein the mass percentage of sodium hydroxide in the aqueous solution is 10%, and the solvent is water; adding the matrix powder to ethanol, wherein the mass ratio of the matrix powder to the ethanol is matrix powder: ethanol = 1:50; stirring and dispersing under ultrasonic conditions for 20 minutes to obtain a suspension, heating the suspension to 75°C in a water bath and keeping it warm, and then adding the suspension to the suspension under stirring. Add the aqueous solution of cerium trichloride and chloroiridic acid, continue stirring at a constant temperature of 75° C. for 10 minutes after the addition is completed, and then add the aqueous solution of sodium hydroxide under stirring, and the volume ratio of the aqueous solution of cerium trichloride, chloroiridic acid, and sodium hydroxide added to the suspension is suspension: aqueous solution of cerium trichloride and chloroiridic acid: aqueous solution of sodium hydroxide = 100:15:9; after the addition is completed, stir at a constant temperature of 75° C. for 1 hour, then separate the solid and liquid, wash the solid phase with deionized water 3 times, and then dry at 90° C. for 30 minutes, and calcine at 510° C. for 1 hour to obtain a doped powder;

[0026] (3) preparing an aqueous solution of glucose, wherein the mass percentage of glucose in the aqueous solution of glucose is 11% and the solvent is water; adding the doping powder to the aqueous solution of glucose, wherein the mass ratio of the doping powder to the aqueous solution of glucose is doping powder: glucose aqueous solution = 1:20; stirring and dispersing the mixture under ultrasonic conditions for 30 minutes to obtain a dispersion, transferring the dispersion into a reactor, sealing the reactor, heating to 180°C and keeping the temperature for 5 hours, then naturally cooling to room temperature, opening the reactor, separating the solid and the liquid, washing the solid phase with deionized water three times, and drying at 60°C for 2 hours to obtain the catalyst.

[0027] Example 3

[0028] A preparation method for efficiently producing calcium oxide using a rare earth-doped catalyst comprises: mixing gypsum and a catalyst in a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, wherein the volume ratio of the hydrogen, carbon dioxide, and nitrogen is hydrogen:carbon dioxide:nitrogen = 2:18:80; and the mass ratio of the gypsum and catalyst is gypsum:catalyst = 100:5; then heating to 1030°C for decomposition for 30 minutes; and purifying the decomposition product to obtain calcium oxide. The purification method comprises: first removing part of the catalyst from the decomposition product through magnetic separation, then adding the magnetically separated powder to water for leaching, filtering, collecting the filtrate, and passing carbon dioxide gas into the filtrate to form a calcium carbonate precipitate, which is then calcined at 550°C for 2 hours to obtain calcium oxide with high purity. The preparation method of the catalyst is as follows:

[0029] (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 55 g / L, the concentration of nickel dichloride is 25 g / L, and the solvent is water; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, and 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process. After the addition is completed, stirring is continued for 10 minutes, and then ammonia water is added, and the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 7 g: 14 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%; the reactor is closed, heated to 150° C. and kept warm for 5 hours, and then naturally cooled to room temperature after the end of the heat preservation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at a temperature of 500-550° C. for 2 hours to obtain a matrix powder;

[0030] (2) preparing an aqueous solution of cerium trichloride and chloroiridic acid, wherein the concentration of cerium trichloride and chloroiridic acid in the aqueous solution is 28 g / L, the concentration of chloroiridic acid is 6 g / L, and the solvent is water; preparing an aqueous solution of sodium hydroxide, wherein the mass percentage of sodium hydroxide in the aqueous solution is 10%, and the solvent is water; adding the matrix powder to ethanol, wherein the mass ratio of the matrix powder to the ethanol is matrix powder: ethanol = 1:50; stirring and dispersing under ultrasonic conditions for 20 minutes to obtain a suspension, heating the suspension to 75°C in a water bath and keeping it warm, and then adding the suspension to the suspension under stirring. Add the aqueous solution of cerium trichloride and chloroiridic acid, continue stirring at a constant temperature of 75° C. for 10 minutes after the addition is completed, and then add the aqueous solution of sodium hydroxide under stirring, and the volume ratio of the aqueous solution of cerium trichloride, chloroiridic acid, and sodium hydroxide added to the suspension is suspension: aqueous solution of cerium trichloride and chloroiridic acid: aqueous solution of sodium hydroxide = 100:16:9; after the addition is completed, stir at a constant temperature of 75° C. for 1 hour, then separate the solid and liquid, wash the solid phase with deionized water 3 times, and then dry at 90° C. for 30 minutes, and calcine at 520° C. for 1 hour to obtain a doped powder;

[0031] (3) preparing an aqueous solution of glucose, wherein the mass percentage of glucose in the aqueous solution of glucose is 11% and the solvent is water; adding the doping powder to the aqueous solution of glucose, wherein the mass ratio of the doping powder to the aqueous solution of glucose is doping powder: glucose aqueous solution = 1:20; stirring and dispersing the mixture under ultrasonic conditions for 30 minutes to obtain a dispersion, transferring the dispersion into a reactor, sealing the reactor, heating to 180°C and keeping the temperature for 5 hours, then naturally cooling to room temperature, opening the reactor, separating the solid and the liquid, washing the solid phase with deionized water three times, and drying at 60°C for 2 hours to obtain the catalyst.

[0032] Example 4

[0033] A preparation method for efficiently producing calcium oxide using a rare earth-doped catalyst comprises: mixing gypsum and a catalyst in a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, wherein the volume ratio of the hydrogen, carbon dioxide, and nitrogen is hydrogen:carbon dioxide:nitrogen = 2:18:80; and the mass ratio of the gypsum and catalyst is gypsum:catalyst = 100:5; then heating to 1030°C for decomposition for 30 minutes; and purifying the decomposition product to obtain calcium oxide. The purification method comprises: first removing part of the catalyst from the decomposition product through magnetic separation, then adding the magnetically separated powder to water for leaching, filtering, collecting the filtrate, and passing carbon dioxide gas into the filtrate to form a calcium carbonate precipitate, which is then calcined at 550°C for 2 hours to obtain calcium oxide with high purity. The preparation method of the catalyst is as follows:

[0034] (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 60 g / L, the concentration of nickel dichloride is 30 g / L, and the solvent is water; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, and 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process. After the addition is completed, stirring is continued for 10 minutes, and then ammonia water is added, and the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 8 g: 15 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%; the reactor is closed, heated to 150° C. and kept warm for 5 hours, and then cooled naturally to room temperature after the end of the heat preservation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at a temperature of 500-550° C. for 2 hours to obtain a matrix powder;

[0035] (2) preparing an aqueous solution of cerium trichloride and chloroiridic acid, wherein the concentration of cerium trichloride and chloroiridic acid in the aqueous solution is 30 g / L, the concentration of chloroiridic acid is 6 g / L, and the solvent is water; preparing an aqueous solution of sodium hydroxide, wherein the mass percentage of sodium hydroxide in the aqueous solution is 10%, and the solvent is water; adding the matrix powder to ethanol, wherein the mass ratio of the matrix powder to ethanol is 1:50; stirring and dispersing for 20 minutes under ultrasonic conditions to obtain a suspension, heating the suspension to 75°C in a water bath and then adding the suspension to the suspension under stirring. Add the aqueous solution of cerium trichloride and chloroiridic acid, continue to stir at a constant temperature of 75° C. for 10 minutes after the addition is completed, and then add the aqueous solution of sodium hydroxide under stirring, and the volume ratio of the aqueous solution of cerium trichloride, chloroiridic acid, and sodium hydroxide added to the suspension is suspension: aqueous solution of cerium trichloride and chloroiridic acid: aqueous solution of sodium hydroxide = 100:16:10; after the addition is completed, stir at a constant temperature of 75° C. for 1 hour, then separate the solid and liquid, wash the solid phase with deionized water 3 times, and then dry at 90° C. for 30 minutes, and calcine at 530° C. for 1 hour to obtain a doped powder;

[0036] (3) preparing an aqueous solution of glucose, wherein the mass percentage of glucose in the aqueous solution of glucose is 12% and the solvent is water; adding the doping powder to the aqueous solution of glucose, wherein the mass ratio of the doping powder to the aqueous solution of glucose is doping powder: aqueous solution of glucose = 1:20; stirring and dispersing the mixture under ultrasonic conditions for 30 minutes to obtain a dispersion, transferring the dispersion into a reactor, sealing the reactor, heating to 180°C and keeping the temperature for 5 hours, then naturally cooling to room temperature, opening the reactor, separating the solid and the liquid, washing the solid phase with deionized water three times, and drying at 60°C for 2 hours to obtain the catalyst.

[0037] Comparative Example 1

[0038] A comparative method for preparing calcium oxide comprises heating gypsum to 1030° C. for decomposition in a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, wherein the volume ratio of the hydrogen, carbon dioxide, and nitrogen is hydrogen:carbon dioxide:nitrogen = 2:18:80; and the decomposition time is 30 minutes. The decomposition product is purified to prepare calcium oxide. The purification method comprises first removing a portion of the catalyst in the decomposition product by magnetic separation, then adding the magnetically separated powder to water for rinsing, filtering, collecting the filtrate, passing carbon dioxide gas into the filtrate to form a calcium carbonate precipitate, and then calcining at 550° C. for 2 hours to obtain calcium oxide of higher purity.

[0039] Comparative Example 2

[0040] A comparative method for preparing calcium oxide comprises mixing gypsum and a catalyst in a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, wherein the volume ratio of the hydrogen, carbon dioxide, and nitrogen is hydrogen:carbon dioxide:nitrogen = 2:18:80; and the mass ratio of the gypsum and catalyst is gypsum:catalyst = 100:5; then heating to 1030°C for decomposition for 30 minutes; and purifying the decomposition product to prepare calcium oxide. The purification method comprises first removing part of the catalyst from the decomposition product by magnetic separation, then adding the magnetically separated powder to water for leaching, filtering, collecting the filtrate, and passing carbon dioxide gas into the filtrate to form a calcium carbonate precipitate, which is then calcined at 550°C for 2 hours to obtain calcium oxide of higher purity. The catalyst preparation method is as follows:

[0041] (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 55 g / L, the concentration of nickel dichloride is 25 g / L, and the solvent is water; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, and 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process, and the stirring is continued for 10 minutes after the addition is completed, and then ammonia water is added, and the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 7 g: 12 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%; the reactor is closed, heated to 150° C. and kept warm for 5 hours, and then naturally cooled to room temperature after the end of the heat preservation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at 520° C. for 2 hours to obtain a matrix powder;

[0042] (2) preparing an aqueous solution of cerium trichloride, wherein the concentration of cerium trichloride in the aqueous solution is 24 g / L and the solvent is water; preparing an aqueous solution of sodium hydroxide, wherein the mass percentage of sodium hydroxide in the aqueous solution is 10% and the solvent is water; adding the matrix powder to ethanol, wherein the mass ratio of the matrix powder to the ethanol is 1:50; stirring and dispersing the matrix powder under ultrasonic conditions for 20 minutes to obtain a suspension, heating the suspension to 75° C. in a water bath and then adding the matrix powder to the suspension under stirring. The cerium aqueous solution was stirred at a constant temperature of 75° C. for 10 minutes after the addition was completed, and then the sodium hydroxide aqueous solution was added under stirring. The volume ratio of the cerium trichloride aqueous solution and the sodium hydroxide aqueous solution added to the suspension was suspension: cerium trichloride aqueous solution: sodium hydroxide aqueous solution = 100:15:9; after the addition was completed, the mixture was stirred at a constant temperature of 75° C. for 1 hour, and then the solid-liquid separation was carried out. The solid phase was washed with deionized water 3 times, and then dried at 90° C. for 30 minutes and calcined at 510° C. for 1 hour to obtain the doped powder of this comparative example;

[0043] (3) A glucose aqueous solution was prepared, wherein the mass percentage of glucose in the glucose aqueous solution was 11% and the solvent was water; the doping powder was added to the glucose aqueous solution, wherein the mass ratio of the doping powder to the glucose aqueous solution was doping powder: glucose aqueous solution = 1:20; the dispersion was obtained by stirring and dispersing under an ultrasonic environment for 30 minutes, and the dispersion was transferred to a reactor, the reactor was sealed, heated to 180°C and kept warm for 5 hours, and then naturally cooled to room temperature, the reactor was opened, the solid-liquid separation was carried out, the solid phase was washed 3 times with deionized water, and dried at 60°C for 2 hours to obtain the catalyst described in this comparative example.

[0044] Comparative Example 3

[0045] A comparative method for preparing calcium oxide comprises mixing gypsum and a catalyst in a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, wherein the volume ratio of the hydrogen, carbon dioxide, and nitrogen is hydrogen:carbon dioxide:nitrogen = 2:18:80; and the mass ratio of the gypsum and catalyst is gypsum:catalyst = 100:5; then heating to 1030°C for decomposition for 30 minutes; and purifying the decomposition product to prepare calcium oxide. The purification method comprises first removing part of the catalyst from the decomposition product by magnetic separation, then adding the magnetically separated powder to water for leaching, filtering, collecting the filtrate, and passing carbon dioxide gas into the filtrate to form a calcium carbonate precipitate, which is then calcined at 550°C for 2 hours to obtain calcium oxide of higher purity. The catalyst preparation method is as follows:

[0046] (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 55 g / L, the concentration of nickel dichloride is 25 g / L, and the solvent is water; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, and 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process, and the stirring is continued for 10 minutes after the addition is completed, and then ammonia water is added, and the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 7 g: 12 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%; the reactor is closed, heated to 150° C. and kept warm for 5 hours, and then naturally cooled to room temperature after the end of the heat preservation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at 520° C. for 2 hours to obtain a matrix powder;

[0047] (2) preparing an aqueous solution of iridium chloride, wherein the concentration of iridium chloride in the aqueous solution is 5 g / L and the solvent is water; preparing an aqueous solution of sodium hydroxide, wherein the mass percentage of sodium hydroxide in the aqueous solution is 10% and the solvent is water; adding the matrix powder to ethanol, wherein the mass ratio of the matrix powder to ethanol is 1:50; stirring and dispersing for 20 minutes under ultrasonic conditions to obtain a suspension, heating the suspension to 75° C. in a water bath and keeping it warm, and then adding the iridium chloride to the suspension under stirring. The aqueous solution was stirred at a constant temperature of 75° C. for 10 minutes after the addition was completed, and then the aqueous solution of sodium hydroxide was added under stirring. The volume ratio of the aqueous solution of chloroiridic acid and the aqueous solution of sodium hydroxide added to the suspension was suspension: aqueous solution of chloroiridic acid: aqueous solution of sodium hydroxide = 100:15:9; after the addition was completed, the mixture was stirred at a constant temperature of 75° C. for 1 hour, and then the solid-liquid was separated. The solid phase was washed 3 times with deionized water, and then dried at 90° C. for 30 minutes and calcined at 510° C. for 1 hour to obtain the doped powder of this comparative example;

[0048] (3) A glucose aqueous solution was prepared, wherein the mass percentage of glucose in the glucose aqueous solution was 11% and the solvent was water; the doping powder was added to the glucose aqueous solution, wherein the mass ratio of the doping powder to the glucose aqueous solution was doping powder: glucose aqueous solution = 1:20; the dispersion was obtained by stirring and dispersing under an ultrasonic environment for 30 minutes, and the dispersion was transferred to a reactor, the reactor was sealed, heated to 180°C and kept warm for 5 hours, and then naturally cooled to room temperature, the reactor was opened, the solid-liquid separation was carried out, the solid phase was washed 3 times with deionized water, and dried at 60°C for 2 hours to obtain the catalyst described in this comparative example.

[0049] Comparative Example 4

[0050] A comparative method for preparing calcium oxide comprises mixing gypsum and a catalyst in a reaction atmosphere of a mixed gas of hydrogen, carbon dioxide, and nitrogen, wherein the volume ratio of the hydrogen, carbon dioxide, and nitrogen is hydrogen:carbon dioxide:nitrogen = 2:18:80; and the mass ratio of the gypsum and catalyst is gypsum:catalyst = 100:5; then heating to 1030°C for decomposition for 30 minutes; and purifying the decomposition product to prepare calcium oxide. The purification method comprises first removing part of the catalyst from the decomposition product by magnetic separation, then adding the magnetically separated powder to water for leaching, filtering, collecting the filtrate, and passing carbon dioxide gas into the filtrate to form a calcium carbonate precipitate, which is then calcined at 550°C for 2 hours to obtain calcium oxide of higher purity. The catalyst preparation method is as follows:

[0051] (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 55 g / L, the concentration of nickel dichloride is 25 g / L, and the solvent is water; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, and 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process, and the stirring is continued for 10 minutes after the addition is completed, and then ammonia water is added, and the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 7 g: 12 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%; the reactor is closed, heated to 150° C. and kept warm for 5 hours, and then naturally cooled to room temperature after the end of the heat preservation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at 520° C. for 2 hours to obtain a matrix powder;

[0052] (2) Prepare an aqueous solution of cerium trichloride and chloroiridic acid, wherein the concentration of cerium trichloride and chloroiridic acid in the aqueous solution is 24 g / L, the concentration of chloroiridic acid is 5 g / L, and the solvent is water; prepare an aqueous solution of sodium hydroxide, wherein the mass percentage of sodium hydroxide in the aqueous solution is 10%, and the solvent is water; add the matrix powder to ethanol, wherein the mass ratio of the matrix powder to ethanol is 1:50; stir and disperse under ultrasonic conditions for 20 minutes to obtain a suspension, heat the suspension to 75°C in a water bath and keep it warm, and then add the matrix powder to the suspension under stirring. After the addition of the aqueous solution of cerium trichloride and chloroiridic acid, stirring was continued at a constant temperature of 75° C. for 10 minutes, and then the aqueous solution of sodium hydroxide was added under stirring. The volume ratio of the aqueous solution of cerium trichloride, chloroiridic acid, and sodium hydroxide added to the suspension was suspension: aqueous solution of cerium trichloride and chloroiridic acid: aqueous solution of sodium hydroxide = 100:15:9; after the addition was completed, stirring was continued at a constant temperature of 75° C. for 1 hour, and then solid-liquid separation was performed. The solid phase was washed 3 times with deionized water, and then dried at 90° C. for 30 minutes and calcined at 510° C. for 1 hour to obtain the catalyst described in this comparative example.

[0053] Example 5

[0054] The calcium sulfate content in the gypsum and the calcium oxide content in the decomposition products (before purification) prepared by the methods described in the above examples and comparative examples were tested, and the yield of calcium oxide in each example and comparative example was calculated. The results are shown in Table 1.

[0055] As shown in Table 1, the catalyst prepared by the method of the present invention can be added to gypsum for thermal decomposition, which can significantly promote the decomposition of calcium sulfate into calcium oxide, reduce the time required for thermal decomposition, increase the yield of calcium oxide, and help improve production efficiency and reduce costs. The main reaction formula for the decomposition of gypsum to produce calcium oxide in the present invention is:

[0056] (1);

[0057] (2);

[0058] First, an iron-nickel composite oxide matrix powder is prepared to form the matrix oxide of the catalyst, wherein the above step (2) is a reaction between solids and solids, and requires a molten state to promote the reaction. The iron-nickel composite oxide can lower the melting point of the solid mixture, so that a eutectic is formed at a decomposition temperature of 1030°C. At the same time, iron and nickel can also promote the ionization of calcium sulfate and calcium sulfide, thereby increasing the reaction rate of the above step (2), thereby increasing the rate of the overall decomposition reaction and improving the yield of the target product calcium oxide within a decomposition time of 30 minutes. 1-ethyl-3-methylimidazole chloride is introduced into the process of preparing the iron-nickel composite oxide. Since 1-ethyl-3-methylimidazole chloride can be preferentially adsorbed on the crystal surface of the generated composite oxide through electrostatic action, the growth rate of the composite oxide is reduced, so that the nucleation rate is greater than the growth rate, which plays a role in refining the particles and improving the catalytic activity of the catalyst. Then, a rare earth-iridium composite oxide layer is formed on the surface of the base powder. The rare earth-iridium composite oxide layer can provide more catalytic active sites for hydrogen absorption and desorption. By utilizing the characteristic that rare earth elements easily absorb hydrogen to form corresponding rare earth hydrides, the contact between calcium sulfate and hydrogen is promoted, the activation energy barrier of the first step reaction is reduced, and the reaction rate of the above step (1) is increased. Finally, a porous carbon coating layer is formed by pyrolysis of an aqueous solution of glucose. On the one hand, it can improve the catalyst's ability to absorb hydrogen, making hydrogen and calcium sulfate more easily contacted. On the other hand, the carbon layer itself can also act as a reducing component to promote the conversion of part of the calcium sulfate into calcium sulfide, thereby improving the efficiency of the above step (1) reaction.

[0059] Table 1

[0060]

[0061] The technical solutions provided by the present invention are described in detail above. For those skilled in the art, according to the ideas of the embodiments of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for efficiently producing calcium oxide using a rare earth-doped catalyst, characterized in that: In a mixed gas reaction atmosphere of hydrogen, carbon dioxide and nitrogen, gypsum and a catalyst are mixed, and then heated to 1020-1050°C for decomposition, and the decomposition product is purified to prepare calcium oxide, wherein the preparation method of the catalyst is: (1) A mixed aqueous solution of ferric chloride and nickel dichloride is prepared in a reactor; the mixed aqueous solution of ferric chloride and nickel dichloride is stirred, 1-ethyl-3-methylimidazole chloride is added to the solution during the stirring process, stirring is continued for more than 10 minutes after the addition is completed, and then ammonia water is added, the reactor is sealed, heated to 150±5°C and kept warm for more than 5 hours, and then naturally cooled to room temperature after the end of the insulation, the reactor is opened, the solid and liquid are separated, and the solid and liquid are calcined at a temperature of 500-550°C to obtain a matrix powder; (2) preparing an aqueous solution of cerium trichloride and chloroiridic acid, and preparing an aqueous solution of sodium hydroxide; adding the matrix powder to ethanol, stirring and dispersing it under ultrasonic conditions for more than 20 minutes to obtain a suspension, heating the suspension in a water bath to 75±3°C and keeping it warm, then adding the aqueous solution of cerium trichloride and chloroiridic acid to the suspension under stirring, continuing to stir at a constant temperature of 75±3°C for more than 10 minutes after the addition is completed, then adding the aqueous solution of sodium hydroxide under stirring, stirring at a constant temperature of 75±3°C for more than 1 hour after the addition is completed, then separating the solid and liquid, washing the solid phase with deionized water for more than 3 times, then drying at 90±10°C for more than 30 minutes, and calcining at a temperature of 500-530°C to obtain a doped powder; (3) preparing an aqueous solution of glucose, adding the doped powder to the aqueous solution of glucose, stirring and dispersing under ultrasonic conditions for more than 30 minutes to obtain a dispersion, transferring the dispersion into a reactor, sealing the reactor, heating to 180±5°C and keeping the temperature for more than 5 hours, then naturally cooling to room temperature, opening the reactor, separating the solid and the liquid, washing the solid phase with deionized water for more than 3 times, and drying to obtain the catalyst.

2. The method for efficiently producing calcium oxide using a rare earth-doped catalyst according to claim 1, characterized in that: The mixing volume ratio of the hydrogen, carbon dioxide and nitrogen is hydrogen:carbon dioxide:nitrogen=2:18:

80.

3. The method for efficiently producing calcium oxide using a rare earth-doped catalyst according to claim 1, wherein: The purification method comprises the following steps: firstly removing part of the catalyst in the decomposition product by magnetic separation, then adding the magnetically separated powder into water for elution, filtering, collecting the filtrate, introducing carbon dioxide gas into the filtrate to generate calcium carbonate precipitate, and then calcining at 550° C. for more than 2 hours to obtain calcium oxide with higher purity.

4. The method for efficiently producing calcium oxide using a rare earth-doped catalyst according to claim 1, wherein: The mass ratio of the gypsum to the catalyst is gypsum:catalyst=100:5-6; the decomposition time after heating to 1020-1050° C. is 30-40 minutes.

5. The method for efficiently producing calcium oxide using a rare earth-doped catalyst according to claim 1, characterized in that: In the step (1), in the mixed aqueous solution of ferric chloride and nickel dichloride, the concentration of ferric chloride is 50-60 g / L, the concentration of nickel dichloride is 20-30 g / L, and the solvent is water.

6. The method for efficiently producing calcium oxide using a rare earth-doped catalyst according to claim 1, characterized in that: In the step (1), the volume ratio of the added amount of 1-ethyl-3-methylimidazole chloride and ammonia water to the mixed aqueous solution of ferric chloride and nickel dichloride is 1-ethyl-3-methylimidazole chloride: ammonia water: mixed aqueous solution of ferric chloride and nickel dichloride = 6-8 g: 10-15 mL: 100 mL, wherein the mass percentage of the solute in the ammonia water is 25%.

7. The method for efficiently producing calcium oxide using a rare earth-doped catalyst according to claim 1, characterized in that: In the step (2), in the aqueous solution of cerium trichloride and chloroiridic acid, the concentration of cerium trichloride is 20-30 g / L, the concentration of chloroiridic acid is 5-6 g / L, and the solvent is water; in the aqueous solution of sodium hydroxide, the mass percentage of sodium hydroxide is 10%, and the solvent is water.

8. The method for efficiently producing calcium oxide using a rare earth-doped catalyst according to claim 1, characterized in that: In the step (2), the base powder is added to ethanol in a mass ratio of base powder: ethanol = 1:50; the cerium trichloride, the aqueous solution of chloroiridic acid, and the aqueous solution of sodium hydroxide are added to the suspension in a volume ratio of suspension: cerium trichloride, the aqueous solution of chloroiridic acid: the aqueous solution of sodium hydroxide = 100:15-16:8-10.

9. The method for efficiently producing calcium oxide using a rare earth-doped catalyst according to claim 1, wherein: In the step (3), the mass percentage of glucose in the glucose aqueous solution is 10% to 12%, and the solvent is water; the doping powder is added to the glucose aqueous solution in a mass ratio of doping powder to glucose aqueous solution = 1:20.

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