阅读说明：本技术 一种用二氧化碳制备氢氧化钠的方法 (Method for preparing sodium hydroxide by using carbon dioxide ) 是由 汪伟国 张维帮 于 2020-09-24 设计创作，主要内容包括：本发明提供一种用二氧化碳制备氢氧化钠的方法,属于二氧化碳回收利用技术领域。一种用二氧化碳制备氢氧化钠的方法,包括以下步骤；(1)将氧化钙、硫酸钠固体进行得到混合粉料；(2)将混合粉料加入水中；(3)在搅拌的情况下通入二氧化碳气体,得到混合溶液；(4)向混合溶液中加入氢氧化钙溶液,反应完全后得到浑浊溶液；(5)将步骤(4)的浑浊溶液静置后过滤,得到碳酸钙沉淀和硫酸钙、氢氧化钠混合溶液；(6)调节硫酸钙、氢氧化钠混合溶液的温度使得硫酸钙逐渐析出,得到氢氧化钠溶液。本申请能够吸收汽车尾气等产生的二氧化碳,不但提高了二氧化碳的吸收率还生产出价格更高的氢氧化钠,终产物碳酸钙也可以作为其他的生产原料。(The invention provides a method for preparing sodium hydroxide by using carbon dioxide, belonging to the technical field of carbon dioxide recycling. A method for preparing sodium hydroxide by using carbon dioxide comprises the following steps; (1) carrying out solid treatment on calcium oxide and sodium sulfate to obtain mixed powder; (2) adding the mixed powder into water; (3) introducing carbon dioxide gas under the condition of stirring to obtain a mixed solution; (4) adding a calcium hydroxide solution into the mixed solution, and obtaining a turbid solution after complete reaction; (5) standing the turbid solution obtained in the step (4), and filtering to obtain calcium carbonate precipitate and a mixed solution of calcium sulfate and sodium hydroxide; (6) and adjusting the temperature of the mixed solution of calcium sulfate and sodium hydroxide to gradually separate out the calcium sulfate to obtain a sodium hydroxide solution. The method can absorb the carbon dioxide generated by automobile exhaust and the like, not only improves the absorption rate of the carbon dioxide, but also produces the sodium hydroxide with higher price, and the final product calcium carbonate can also be used as other production raw materials.)

1. A method for preparing sodium hydroxide by using carbon dioxide is characterized by comprising the following steps;

(1) mixing, grinding and sieving calcium oxide and sodium sulfate solids to obtain mixed powder;

(2) adding the mixed powder into water, and continuously stirring;

(3) introducing carbon dioxide gas under the condition of stirring to obtain a mixed solution;

(4) adding a calcium hydroxide solution into the mixed solution, and obtaining a turbid solution after complete reaction;

(5) standing the turbid solution obtained in the step (4), and filtering to obtain calcium carbonate precipitate and a mixed solution of calcium sulfate and sodium hydroxide;

(6) and adjusting the temperature of the mixed solution of calcium sulfate and sodium hydroxide to gradually separate out the calcium sulfate to obtain a sodium hydroxide solution.

2. The method for preparing sodium hydroxide by using carbon dioxide as claimed in claim 1, wherein the mass ratio of the calcium oxide to the calcium sulfate is more than 28: 71.

3. The method for preparing sodium hydroxide by using carbon dioxide as claimed in claim 1, wherein the pressure of the system when the carbon dioxide gas is introduced in the step (3) is 0.5 to 0.7 MPa.

4. The method for preparing sodium hydroxide by using carbon dioxide as claimed in claim 1, wherein the temperature of the system when the carbon dioxide gas is introduced in the step (3) is 15-20 ℃.

5. The method for preparing sodium hydroxide from carbon dioxide as claimed in claim 1, wherein the concentration of the calcium hydroxide solution is 0.015 to 0.2 mol/L.

6. The method for preparing sodium hydroxide by using carbon dioxide as claimed in claim 1, wherein the stirring speed in step (2) is 150-180 rpm.

7. The method for preparing sodium hydroxide by using carbon dioxide as claimed in claim 6, wherein the stirring time in the step (2) is 50-100 min.

Technical Field

The invention belongs to the technical field of carbon dioxide recycling, and particularly relates to a method for preparing sodium hydroxide by using carbon dioxide.

Background

Nowadays, sustainable development is an inevitable choice for the development strategy of the macro economy of each country, environmental protection and reasonable energy utilization become global concerns, and CO₂The greenhouse effect brought by the emission of the greenhouse gases has great influence on the environment in which the human beings depend to liveAnd (6) sounding. However, in order to realize the development of society, a large amount of energy sources such as coal, petroleum, natural gas and the like are inevitably needed, and the use of the energy sources inevitably causes CO in the atmosphere₂Is increased in the amount of these CO₂The direct discharge not only causes serious environmental pollution, but also wastes valuable carbon resources. How to realize CO₂Comprehensive utilization and emission reduction are important points of domestic and foreign research.

CO₂As a carbon resource, the carbon is widely applied to industries such as petrochemical industry, agriculture, food, medicine and the like, with the continuous and deep research, new technology is continuously developed, and CO is₂Will expand the application market, and therefore, CO₂The separation, recovery and comprehensive utilization of the method have wide market prospect.

At present, CO₂The recycling technology mainly comprises a solvent absorption method, a pressure swing adsorption method, a catalytic combustion (catalytic oxidation) method and CO₂And (4) a capture and sealing technology.

Source of carbon dioxide CO₂The source of the (B) is very wide, and the main emission sources mainly comprise the following types:

(1) the chemical plant hydrogen production process needs H in chemical fertilizer plant, oil refinery or other organic chemical plant₂

These H₂Is prepared by converting methane gas, carbon monoxide and other substances with water vapor, and CO is generated in the process₂And H₂，CO₂About 15% or more, and these CO-products₂Most are vented to the atmosphere in the form of tail gas.

(2) The ore decomposition process includes the steps of producing steel, paint, soda ash, etc. with lime, lime stone, magnesia, etc. and the process of producing magnesia brick and refractory brick with great amount of CO exhausted₂。

(3) Oil and gas field during the production of oil and natural gas, mixed oil field gas, in which CO is produced₂The gas content is 15-99%.

(4) In biochemical, food and pharmaceutical industries, alcohol production process by fermentation of white spirit, beer and the likeIn all, a large amount of CO is associated₂The gas content is between 90 and 98 percent, which is better high-concentration CO₂And (4) a gas source.

The CO2 recovery and utilization technology includes physical absorption, chemical absorption, adsorption separation, membrane separation, etc.

(1) The principle of physical absorption is that in the absorbent, CO2 in the raw material gas has high solubility, and other gases have low solubility, so that CO2 is removed. Generally applied to the occasions where the partial pressure of solute gas is higher. Generally, high pressure and low temperature are adopted for absorption, and decompression and heating are adopted for desorption, wherein the energy consumption can be greatly reduced by decompressing and desorbing. The absorbent selected by the physical absorption method has the advantages of good selectivity to CO2, high solubility, stable performance and no corrosiveness.

(2) Chemical absorption method

The principle is that CO2 reacts with a certain solvent to generate an intermediate compound, other gases do not react with the solvent, the generated intermediate compound is decomposed into CO2 and the solvent in another device, CO2 is continuously discharged, and the solvent is recycled, so that the purpose of separating CO2 from other mixed gases is achieved. The method does not need high pressure or low temperature, has high selectivity, can discharge CO2 with the concentration of more than 98 percent, but desorbs CO2 from the solvent by steam heating.

3) Adsorption separation process

The principle is that the adsorbent (natural zeolite, molecular sieve, activated carbon, activated alumina, silica gel and the like) is utilized to selectively and reversibly adsorb CO2 in the raw material gas mixture. Adsorption processes are largely classified into Temperature Swing Adsorption (TSA) and Pressure Swing Adsorption (PSA). The adsorbent typically adsorbs CO2 under low temperature/high pressure conditions and desorbs CO2 after elevated temperature/reduced pressure, effecting separation of CO2 from other gases by periodic temperature/pressure changes. The pressure swing adsorption method has the advantages of simple process, strong adaptability, low energy consumption, no corrosion and the like, but has poor selectivity on CO2 and low CO2 recovery efficiency, and is suitable for the condition of high CO2 concentration.

(4) Membrane separation process

At present, gas separation membranes are mainly divided into inorganic membranes and organic membranes, and are widely applied to the aspects of H2 separation and recovery, N2 and O2 enrichment, CO2 separation and recovery and the like, and polymer membranes for gas separation are asymmetric structures or composite membranes, and the membrane surfaces of the polymer membranes are non-porous structures, namely dense polymer membranes. While inorganic membranes tend to be porous multilayer structures. There is a significant difference in gas permeation mechanism between non-porous and porous structures.

The published Chinese patent with the application number of CN201610497833.2 discloses a recycling system and a method for carbon dioxide in chlorinated hydrocarbon hydrolysis tail gas, which comprises a chlorinated hydrocarbon hydrolysis device, a tail gas absorption tower, an alkali liquor storage tank and a circulating pump, wherein the chlorinated hydrocarbon hydrolysis device provides an environment for hydrolysis reaction for chlorinated hydrocarbon; a tail gas outlet of the chlorinated hydrocarbon hydrolysis device is connected with a gas inlet of the tail gas absorption tower, so that carbon dioxide in the tail gas is contacted with an alkaline solution to absorb the carbon dioxide; the liquid outlet of the tail gas absorption tower is communicated with the alkali liquor storage tank, the lower end of the alkali liquor storage tank is communicated with the tail gas absorption tower through a circulating pump, and the circulating pump provides power to enable the sodium hydroxide solution to circularly enter the tail gas absorption tower to absorb carbon dioxide until sodium carbonate in the sodium hydroxide solution reaches a set concentration. According to the invention, CO2 in the tail gas is absorbed, and the reactant of the chlorinated hydrocarbon hydrolysis reaction is obtained, so that the waste is utilized, the production cost improvement caused by tail gas treatment can be compensated, and the method conforms to the concept of environmental protection.

Most of the carbon dioxide extracted in the prior art is collected, so that the problem of storage is great, the carbon dioxide is absorbed by directly using sodium hydroxide, the waste of resources is caused, the cost is too high, and the utilization rate and the absorption rate of the carbon dioxide are low.

Disclosure of Invention

In view of the above, the present invention provides a method for preparing sodium hydroxide from carbon dioxide, which can absorb carbon dioxide generated from automobile exhaust, etc., and simultaneously produce sodium hydroxide, wherein the method is simple to operate, the absorption rate of carbon dioxide is improved, sodium hydroxide with a higher price is also produced, and the final product calcium carbonate can also be used as other production raw materials.

The invention relates to a method for preparing sodium hydroxide by using carbon dioxide, which comprises the following steps;

(1) mixing, grinding and sieving calcium oxide and sodium sulfate solids to obtain mixed powder, wherein the calcium oxide and the sodium sulfate are uniformly mixed, which is favorable for improving the reaction speed;

(2) adding the mixed powder into water, and continuously stirring;

(3) introducing carbon dioxide gas under the condition of stirring to obtain a mixed solution, wherein the calcium carbonate, the sodium sulfate and the carbon dioxide react under the water system condition, and the specific reaction equation is as follows;

CaO + Na₂SO₄ +2CO₂ + H₂O CaSO₄+2NaHCO₃

Ca（OH）₂+Na₂SO₄ +2CO₂ CaSO₄+2NaHCO₃

(4) adding a calcium hydroxide solution into the mixed solution, wherein the concentration of the calcium hydroxide solution is 0.015-0.2mol/L, obtaining a turbid solution after the reaction is completed, and the amount of the added calcium hydroxide is sufficient, so that the calcium hydroxide solution with high concentration is selected to prevent the generation of sodium carbonate, the adding speed is required to be noticed when the calcium hydroxide solution is added, and the chemical reaction after the calcium hydroxide solution is added is as follows;

NaHCO₃+Ca(OH)₂=CaCO3↓+NaOH+H₂O

(5) standing the turbid solution obtained in the step (4), and filtering to obtain calcium carbonate precipitate and a mixed solution of calcium sulfate and sodium hydroxide;

(6) the temperature of the mixed solution of calcium sulfate and sodium hydroxide is adjusted to gradually separate out the calcium sulfate to obtain the sodium hydroxide solution, and the calcium sulfate is slightly soluble in water, so that the solubility of the calcium sulfate changes along with the change of the temperature, and the calcium sulfate can be separated out to obtain the sodium hydroxide solution.

Wherein the mass ratio of the calcium oxide to the calcium sulfate is more than 28: 71.

When carbon dioxide gas is introduced in the step (3), the pressure of the system is 0.5-0.7MPa, and the temperature is 15-20 ℃. The temperature and pressure can directly influence the solubility of carbon dioxide, and the solubility of gas increases with the increase of pressure and decreases with the decrease of pressure. The solubility of the gas decreases with increasing temperature and increases with decreasing temperature. In the invention, the pressure is set to be 0.5-0.7MPa, and the temperature is set to be 15-20 ℃, so that the solubility of carbon dioxide in the mixed solution can be higher, and the reaction rate and the carbon dioxide absorption rate are improved.

The rotation speed of the stirring in the step (2) is 150-180rpm, and the stirring time is 50-100 min.

The method can absorb the carbon dioxide generated by automobile exhaust and the like, simultaneously produce the sodium hydroxide, is simple to operate, not only improves the absorption rate of the carbon dioxide, but also produces the sodium hydroxide with higher price, and the final product calcium carbonate can also be used as other production raw materials.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Example 1

The invention relates to a method for preparing sodium hydroxide by using carbon dioxide, which comprises the following steps;

(1) mixing, grinding and sieving calcium oxide and sodium sulfate solids to obtain mixed powder, wherein the calcium oxide and the sodium sulfate are uniformly mixed, which is favorable for improving the reaction speed;

(2) adding the mixed powder into water, and continuously stirring;

(3) introducing carbon dioxide gas under the condition of stirring to obtain a mixed solution, wherein the calcium carbonate, the sodium sulfate and the carbon dioxide react under the water system condition, and the specific reaction equation is as follows;

CaO + Na₂SO₄ +2CO₂ + H₂O CaSO₄+2NaHCO₃

Ca（OH）₂+Na₂SO₄ +2CO₂ CaSO₄+2NaHCO₃

(4) adding a calcium hydroxide solution into the mixed solution, wherein the concentration of the calcium hydroxide solution is 0.015mol/L, obtaining a turbid solution after the reaction is completed, and the amount of the added calcium hydroxide is sufficient, so that the calcium hydroxide solution with high concentration is selected to prevent the generation of sodium carbonate, the adding speed is required to be noticed when the calcium hydroxide solution is added, and the chemical reaction after the calcium hydroxide solution is added is as follows;

NaHCO₃+Ca(OH)₂=CaCO3↓+NaOH+H₂O

(5) standing the turbid solution obtained in the step (4), and filtering to obtain calcium carbonate precipitate, calcium sulfate,

A sodium hydroxide mixed solution;

(6) adjusting the temperature of the mixed solution of calcium sulfate and sodium hydroxide to gradually separate out calcium sulfate and obtain hydrogen

The sodium oxide solution, because calcium sulfate is slightly soluble in water, the solubility of calcium sulfate changes with the change of temperature, and the calcium sulfate can be separated out to obtain the sodium hydroxide solution.

Wherein the mass ratio of the calcium oxide to the calcium sulfate is 29: 71.

And (3) introducing carbon dioxide gas at a pressure of 0.5MPa and a temperature of 15 ℃. The temperature and pressure can directly influence the solubility of carbon dioxide, and the solubility of gas increases with the increase of pressure and decreases with the decrease of pressure. The solubility of the gas decreases with increasing temperature and increases with decreasing temperature. In the invention, the pressure is set to be 0.5-0.7MPa, and the temperature is set to be 15-20 ℃, so that the solubility of carbon dioxide in the mixed solution can be higher, and the reaction rate and the carbon dioxide absorption rate are improved.

The rotating speed of the stirring in the step (2) is 150rpm, and the stirring time is 100 min.

Example 2

The invention relates to a method for preparing sodium hydroxide by using carbon dioxide, which comprises the following steps;

(1) mixing, grinding and sieving calcium oxide and sodium sulfate solids to obtain mixed powder, wherein the calcium oxide and the sodium sulfate are uniformly mixed, which is favorable for improving the reaction speed;

(2) adding the mixed powder into water, and continuously stirring;

(3) introducing carbon dioxide gas under the condition of stirring to obtain a mixed solution, wherein the calcium carbonate, the sodium sulfate and the carbon dioxide react under the water system condition, and the specific reaction equation is as follows;

CaO + Na₂SO₄ +2CO₂ + H₂O CaSO₄+2NaHCO₃

Ca（OH）₂+Na₂SO₄ +2CO₂ CaSO₄+2NaHCO₃

(4) adding a calcium hydroxide solution into the mixed solution, wherein the concentration of the calcium hydroxide solution is 0.2mol/L, obtaining a turbid solution after the reaction is completed, and the amount of the added calcium hydroxide is sufficient, so that the calcium hydroxide solution with high concentration is selected to prevent the generation of sodium carbonate, the adding speed is required to be noticed when the calcium hydroxide solution is added, and the chemical reaction after the calcium hydroxide solution is added is as follows;

NaHCO₃+Ca(OH)₂=CaCO3↓+NaOH+H₂O

(5) standing the turbid solution obtained in the step (4), and filtering to obtain calcium carbonate precipitate, calcium sulfate,

A sodium hydroxide mixed solution;

(6) adjusting the temperature of the mixed solution of calcium sulfate and sodium hydroxide to gradually separate out calcium sulfate and obtain hydrogen

The sodium oxide solution, because calcium sulfate is slightly soluble in water, the solubility of calcium sulfate changes with the change of temperature, and the calcium sulfate can be separated out to obtain the sodium hydroxide solution.

Wherein the mass ratio of the calcium oxide to the calcium sulfate is 33: 71.

And (3) introducing carbon dioxide gas at a pressure of 0.7MPa and a temperature of 20 ℃.

The stirring speed in the step (2) is 170rpm, and the stirring time is 60 min.

Example 3

The invention relates to a method for preparing sodium hydroxide by using carbon dioxide, which comprises the following steps;

(1) mixing, grinding and sieving calcium oxide and sodium sulfate solids to obtain mixed powder, wherein the calcium oxide and the sodium sulfate are uniformly mixed, which is favorable for improving the reaction speed;

(2) adding the mixed powder into water, and continuously stirring;

(3) introducing carbon dioxide gas under the condition of stirring to obtain a mixed solution, wherein the calcium carbonate, the sodium sulfate and the carbon dioxide react under the water system condition, and the specific reaction equation is as follows;

CaO + Na₂SO₄ +2CO₂ + H₂O CaSO₄+2NaHCO₃

Ca（OH）₂+Na₂SO₄ +2CO₂ CaSO₄+2NaHCO₃

(4) adding a calcium hydroxide solution into the mixed solution, wherein the concentration of the calcium hydroxide solution is 0.018mol/L, obtaining a turbid solution after the reaction is completed, and the amount of the added calcium hydroxide is sufficient, so that the calcium hydroxide solution with high concentration is selected to prevent the generation of sodium carbonate, the adding speed is required to be noticed when the calcium hydroxide solution is added, and the chemical reaction after the calcium hydroxide solution is added is as follows;

NaHCO₃+Ca(OH)₂=CaCO3↓+NaOH+H₂O

(5) standing the turbid solution obtained in the step (4), and filtering to obtain calcium carbonate precipitate, calcium sulfate,

A sodium hydroxide mixed solution;

(6) adjusting the temperature of the mixed solution of calcium sulfate and sodium hydroxide to gradually separate out calcium sulfate and obtain hydrogen

The sodium oxide solution, because calcium sulfate is slightly soluble in water, the solubility of calcium sulfate changes with the change of temperature, and the calcium sulfate can be separated out to obtain the sodium hydroxide solution.

Wherein the mass ratio of the calcium oxide to the calcium sulfate is 29: 71.

And (3) introducing carbon dioxide gas at a pressure of 0.6MPa and a temperature of 17 ℃. The stirring speed in the step (2) is 180rpm, and the stirring time is 50 min.

The method can absorb the carbon dioxide generated by automobile exhaust and the like, simultaneously produce the sodium hydroxide, is simple to operate, not only improves the absorption rate of the carbon dioxide, but also produces the sodium hydroxide with higher price, and the final product calcium carbonate can also be used as other production raw materials.

The present invention is not limited to the above-described specific embodiments, and various modifications and variations are possible. Any modifications, equivalents, improvements and the like made to the above embodiments in accordance with the technical spirit of the present invention should be included in the scope of the present invention.