Preparation method of high-purity chlorine dioxide

Abstract

The invention discloses a preparation method of high-purity chlorine dioxide, which relates to the field of preparation of chlorine dioxide, and comprises the following steps: adding a reagent A and a reagent B into a reaction kettle for reaction to prepare chlorine dioxide, wherein the reagent A comprises chlorate, hydrogen peroxide, a stabilizer and water, and the reagent B comprises sulfuric acid, a catalyst and water. Under the action of the stabilizer and the catalyst, chlorate reacts with hydrogen peroxide in the acidic medium to prepare chlorine dioxide, so that the purposes of improving the purity of the prepared chlorine dioxide and the conversion rate of chlorate and reducing the reaction acidity are achieved.

Description

Technical Field

[0001] The invention relates to the field of preparation of chlorine dioxide, and in particular to a method for preparing high-purity chlorine dioxide. Background Art

[0002] In the water treatment process, disinfection is a key link in water treatment, and is an important measure to prevent the spread of diseases, ensure water safety, protect the ecological environment, and improve people's health. At present, the main methods used at home and abroad are to disinfect, kill algae, and deodorize water by adding liquid chlorine, sodium hypochlorite, ozone, chlorine dioxide, or irradiating ultraviolet rays to the water to be treated. In practical applications, liquid chlorine is low in cost, but it is not safe during transportation, storage, and use. During the disinfection process, it will also react with organic pollutants in the water (such as humic acid, etc.) to generate carcinogenic, teratogenic, and mutagenic substances that are difficult to remove; sodium hypochlorite has poor stability, short storage time, poor disinfection effect, and will also produce toxic "three-causing" substances; ozone has a good disinfection effect, but the investment and application costs are extremely high; although ultraviolet rays do not produce three-causing substances, they do not have continuous disinfection capabilities, and the conditions of use are limited; chlorine dioxide not only has a good disinfection effect, but also has a low cost and does not produce "three-causing" substances. It is currently the green disinfectant with the best comprehensive effect.

[0003] At present, the main methods for preparing chlorine dioxide are the chlorite method and the chlorate method. Since the cost of preparing chlorine dioxide from chlorite is high and it is not suitable for places where chlorine dioxide is used in large quantities, the chlorate method is widely used. The chlorate method mainly uses sodium chlorate and sulfuric acid as raw materials, and hydrogen peroxide, methanol, sucrose, urea, etc. as reducing agents. Sodium chlorate is reduced to generate chlorine dioxide under a certain temperature and negative pressure. However, the chlorate method for preparing chlorine dioxide has the following disadvantages:

[0004] 1. The conversion rate of the main raw material chlorate is about 85%, and the reaction acidity is high, resulting in high application costs and easily causing the chlorate content in the treated water to exceed the standard;

[0005] 2. The preparation of chlorine dioxide needs to be carried out under high acidity conditions of more than 5 moles, which not only consumes a lot of acid and increases the application cost, but also the unreacted raw materials enter the water to be treated, causing new pollution. Therefore, the promotion and application of chlorine dioxide is seriously restricted.

[0006] It can be seen that the existing technology for preparing chlorine dioxide has technical problems such as low chlorate conversion rate, high raw material consumption, high application cost, and secondary pollution to the treated water. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing high-purity chlorine dioxide, in which chlorate reacts with hydrogen peroxide in an acidic medium under the action of a stabilizer and a catalyst to prepare chlorine dioxide, so as to solve the problems of low purity of chlorine dioxide and low chlorate conversion rate in the prior art.

[0008] The embodiment of the present invention is implemented by the following technical scheme: The embodiment of the present invention provides a method for preparing high-purity chlorine dioxide, comprising adding reagent A and reagent B into a reaction kettle to react and prepare chlorine dioxide;

[0009] Wherein, the A reagent includes chlorate, hydrogen peroxide, stabilizer and water, and the B reagent includes sulfuric acid, catalyst and water. Specifically, the reaction principle of chlorate and hydrogen peroxide is as follows, taking sodium chlorate as an example:

[0010] 2NaClO3+H2O2+2HSO4→2Na2SO4+2ClO2+2H2O+O2

[0011] The reaction is carried out in an acidic medium, and sulfuric acid (H2SO4) provides an acidic environment to promote the reaction.

[0012] Since hydrogen peroxide is easily decomposed during storage and use, the embodiment of the present invention adds a stabilizer to prevent the spontaneous decomposition of hydrogen peroxide, prolong its shelf life, reduce the consumption of hydrogen peroxide, and the stabilizer can also maintain the stability of hydrogen peroxide during the reaction to ensure the smooth progress of the reaction. In an embodiment of the present invention, through the effect of a catalyst, efficient chlorine dioxide generation can be achieved under relatively low acidity conditions, reducing acid consumption and reducing application costs. At the same time, the catalyst can effectively inhibit the occurrence of side reactions, reduce the generation of chlorine (Cl2), and improve the purity of chlorine dioxide.

[0013] Optionally, in the reagent A, the mass percentage of the chlorate is 28-45%, the mass percentage of hydrogen peroxide is 4-12%, the mass percentage of the stabilizer is 0.03-0.2%, and the rest is water;

[0014] The pH value of the agent A is 0.5 to 3.5, ensuring that the reaction is carried out under suitable acidic conditions and improving the reaction efficiency. At the same time, the acidity is lower than that in the prior art process, reducing environmental pollution and use costs.

[0015] Optionally, in the reagent B, the mass percentage of sulfuric acid is 40-75%, the mass percentage of the catalyst is 0.0005-0.002%, and the rest is water.

[0016] Optionally, the volume ratio of reagent A to reagent B is 1:0.3-1.5.

[0017] Optionally, the stabilizer includes hydroxyethylidene diphosphonic acid and sodium diethylenetriamine penta(methylenephosphonic acid).

[0018] Specifically, hydroxyethylidene diphosphonic acid (HEDP) is an organic phosphonate compound with strong chelating ability and can bind to metal ions (such as Ca 2+ Mg 2+ HEDP has good chemical stability under high temperature environment and is not easy to hydrolyze and decompose.

[0019] Sodium diethylenetriamine penta (methylene phosphonate) (DTPMPA) is an organic phosphonate compound with strong chelating ability and good dispersibility. It is easily soluble in acidic solution, has excellent scale and corrosion inhibition effects, and has good temperature resistance, and can inhibit the formation of carbonate and sulfate scale.

[0020] Optionally, the mass fraction of the hydroxyethylidene diphosphonic acid in the stabilizer is 10-35%, and the mass fraction of the diethylenetriamine penta (methylene phosphonic acid) sodium in the stabilizer is 10-35%; the two substances form hydrogen peroxide protective colloid, free radical scavenging groups and can form stable complexes with metal ions in the solution, thereby preventing the decomposition of hydrogen peroxide.

[0021] The stabilizer also includes sodium nitrate with a mass fraction of 30 to 80%. Sodium nitrate mainly acts as a catalyst to slow down the decomposition rate of hydrogen peroxide. This mechanism mainly achieves the stabilization effect by affecting the chemical reaction rate of hydrogen peroxide decomposition; at the same time, chemical reactions are used to convert impurities in hydrogen peroxide into harmless substances, thereby reducing the decomposition rate of hydrogen peroxide. Hydrogen peroxide is easily affected by impurities during the decomposition process. These impurities may come from residues in the production process or pollutants in the storage container. In the embodiment of the present invention, the hydrogen peroxide stabilizer reacts chemically with these impurities to convert them into relatively stable substances, thereby reducing the decomposition rate of hydrogen peroxide.

[0022] Specifically, sodium nitrate can provide a stable ionic environment in the reaction solution, further reducing the spontaneous decomposition of hydrogen peroxide. The nitrate ions (NO3 -) can enhance the degree of solvation, improve the antioxidant properties of the electrolyte, help stabilize hydrogen peroxide and prevent it from decomposing during the reaction. At the same time, sodium nitrate can form a protective film in the reaction system, which can effectively isolate metal ions and prevent metal ions from catalytic decomposition of hydrogen peroxide. The mass fraction of sodium nitrate is limited to 30-80%, and its high content can further improve the stability of the stabilizer. The addition of sodium nitrate not only provides a stable ion environment, but also enhances the protective effect on hydrogen peroxide through the above mechanism. The mass fractions of HEDP and DTPMPA are 10-35%, respectively, which can ensure that metal ions can be effectively chelated under different conditions to prevent the decomposition of hydrogen peroxide. The synergistic effect of the two can provide more comprehensive protection.

[0023] The stabilizer combination of the above three substances can form a stable complex with the metal ions in the solution, form a free scavenging group, protect the colloid, and at the same time reduce the decomposition reaction through catalysis and react the impurities in the solution into substances without decomposition effect. The purpose of stabilizing hydrogen peroxide and reducing the decomposition of hydrogen peroxide is achieved through the synergistic effect of the three substances.

[0024] Optionally, the catalyst includes at least one of ruthenium trichloride, palladium dichloride and platinum dichloride.

[0025] Specifically, ruthenium trichloride is a highly efficient catalyst that can significantly reduce the activation energy of the reaction, thereby accelerating the reaction rate. It forms an intermediate state with the reactants, changes the reaction path, and makes the reaction easier to proceed. During the catalytic process, ruthenium trichloride can form active intermediates with chlorate and hydrogen peroxide, promoting the generation of chlorine dioxide.

[0026] Palladium dichloride has good catalytic activity and selectivity. It adsorbs reactant molecules, reduces the activation energy of the reaction, and accelerates the reaction rate. Palladium dichloride exhibits excellent catalytic performance in an acidic environment and can effectively promote the reaction of chlorate and hydrogen peroxide to generate high-purity chlorine dioxide.

[0027] Platinum dichloride is a noble metal catalyst with good catalytic activity and stability. It forms an intermediate state with the reactants, reduces the activation energy of the reaction, and accelerates the reaction rate. Platinum dichloride exhibits excellent catalytic performance in an acidic environment and can effectively promote the reaction of chlorate and hydrogen peroxide to generate high-purity chlorine dioxide.

[0028] Optionally, the catalyst includes ruthenium trichloride, palladium dichloride and platinum dichloride, and the mass ratio is 4:2 to 4:2 to 4.

[0029] Ruthenium trichloride, palladium dichloride and platinum dichloride can work together to form more stable active intermediates. These intermediates can more effectively promote the reaction between chlorate and hydrogen peroxide and improve the efficiency of chlorine dioxide generation. At the same time, they can work together to improve the selectivity of the reaction, reduce the occurrence of side reactions, and improve the purity of chlorine dioxide.

[0030] Optionally, the chlorate includes at least one of sodium chlorate, potassium chlorate and barium chlorate.

[0031] Specifically, chlorate is a class of solids containing chlorate ions (ClO3 - ) compound, wherein the oxidation state of the chlorine atom is +5. Chlorate has strong oxidizing properties and should be stored away from contact with organic materials and reducing substances. The production and use costs of sodium chlorate and potassium chlorate are relatively low, and no harmful waste gas and waste water are generated. Barium chlorate has high reaction efficiency in an acidic environment, can quickly generate chlorine dioxide, and reduce the generation of impurities. Sodium chlorate and potassium chlorate are relatively stable at room temperature, easy to operate, and have low risk of use. Although barium chlorate shows excellent reaction efficiency, its cost is relatively high. When used, the three substances can be used in two or three combinations.

[0032] Optionally, the temperature range of 50-80° C. can optimize the conversion rate of chlorate. In this temperature range, the reaction of chlorate with hydrogen peroxide is more complete, and chlorine dioxide can be generated more effectively without causing excessive decomposition or other side reactions.

[0033] In the embodiment of the present invention, the reaction rate is significantly improved within the temperature range of 50 to 80°C, and high-purity chlorine dioxide can be generated more effectively. It should be noted that the temperature range of 50 to 80°C is relatively low compared to the existing process, which can reduce the energy required to heat the reactor and reduce production costs. The reaction conditions of the embodiment of the present invention are relatively mild, and the requirements for equipment are relatively low, which further reduces production costs.

[0034] Compared with the prior art, the embodiments of the present invention have the following advantages and beneficial effects:

[0035] 1. Embodiments of the present invention In the embodiments of the present invention, chlorate is reacted with hydrogen peroxide in an acidic medium under the action of a stabilizer and a catalyst to prepare chlorine dioxide. The raw material conversion rate of the prepared chlorine dioxide can reach more than 95%, and the purity of chlorine dioxide can reach more than 98%. Reagent A and reagent B are configured separately, which improves the safety of the operation process. At the same time, the acidity of the reaction medium is reduced to less than 3.5 moles, which reduces the preparation cost of chlorine dioxide by more than 30% and the residual liquid by more than 45% compared with the prior art, and can greatly reduce disinfection by-products, with significant economic and social benefits.

[0036] 2. The embodiment of the present invention selects the stabilizer to be added so that the stabilizer forms a stable complex or chelate with the metal ions in the solution, thereby improving the shelf life of hydrogen peroxide and maintaining the stability of hydrogen peroxide during the reaction process to ensure the smooth progress of the reaction. By combining hydroxyethylidene diphosphonic acid, sodium diethylenetriamine penta (methylene phosphonate) and sodium nitrate as a stabilizer, the synergistic effect of the three can provide more comprehensive protection for the preparation of chlorine dioxide.

[0037] 3. The three different catalysts of ruthenium trichloride, palladium dichloride and platinum dichloride used in the embodiment of the present invention all have obvious catalytic effects on the preparation of chlorine dioxide. When the three catalysts are used in combination, the catalytic effect is significantly improved.

[0038] 4. In the embodiment of the present invention, by limiting the composition and ratio of reagent A, the composition and ratio of reagent B, the volume ratio of reagent A and reagent B, and the precise restriction of the reaction temperature, the raw material conversion rate of the prepared chlorine dioxide can reach more than 96%, and the purity of chlorine dioxide can reach more than 98%.

[0039] In general, the method for preparing high-purity chlorine dioxide provided in the embodiments of the present invention prepares chlorine dioxide by reacting chlorate with hydrogen peroxide in an acidic medium under the action of a stabilizer and a catalyst, so as to achieve the purpose of improving the purity of the prepared chlorine dioxide, the chlorate conversion rate and reducing the reaction acidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A schematic diagram of purity detection provided in Example 1 of the present invention;

[0042] Figure 2 This is a schematic diagram of conversion rate detection provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0046] In the description of the present invention, it should be noted that the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0047] Example

[0048] The embodiment of the present invention provides a method for preparing high-purity chlorine dioxide, in which chlorate reacts with hydrogen peroxide in an acidic medium under the action of a stabilizer and a catalyst to prepare high-purity chlorine dioxide. The method is used to solve the technical problems of low chlorate conversion rate, high raw material consumption, high application cost, and easy secondary pollution in the existing chlorine dioxide preparation technology.

[0049] Specifically, in the embodiment of the present invention, chlorate, hydrogen peroxide, stabilizer and water are prepared into reagent A, so that the mass percentage of chlorate in reagent A is 28-45%, the mass percentage of hydrogen peroxide is 4-12%, the mass percentage of stabilizer is 0.03-0.2%, and the rest is water, and the pH value of reagent A is 0.5-3.5. Sulfuric acid, catalyst and water are prepared into reagent B, so that the mass percentage of sulfuric acid in reagent B is 40-75%, the mass percentage of catalyst is 0.0005-0.002%, and the rest is water.

[0050] It should be noted that if sulfuric acid is mixed with sodium chlorate and hydrogen peroxide, a chemical reaction will occur to generate chlorine dioxide, which poses a safety hazard. Therefore, reagent A and reagent B need to be prepared and stored separately.

[0051] The stabilizer is a composition of hydroxyethylidene diphosphonic acid (HEDP), sodium diethylenetriamine penta (methylene phosphonic acid) (DTPMP.Na2), and sodium nitrate. In the stabilizer, the proportions of hydroxyethylidene diphosphonic acid (HEDP) and sodium diethylenetriamine penta (methylene phosphonic acid) (DTPMP.Na2) are 10-35% respectively, and the proportion of sodium nitrate is 30-80%.

[0052] The catalyst is one or a combination of ruthenium trichloride, palladium dichloride and platinum dichloride, wherein platinum dichloride has the best selectivity and makes the purity of chlorine dioxide higher, palladium dichloride has the best catalytic effect and a faster reaction speed, and ruthenium trichloride has a lower cost.

[0053] Preferably, the mass percentage of the chlorate is 35-40%, the mass percentage of hydrogen peroxide is 6-8%, the mass percentage of the stabilizer is 0.06-0.12%, the pH value is 1-2.5, the mass percentage of sulfuric acid is 50-65%, and the mass percentage of the catalyst is 0.001-0.01%.

[0054] Preferably, the chlorate is sodium chlorate, and / or potassium chlorate, and / or barium chlorate. Reagent A and reagent B are added to a chlorine dioxide generator (or reactor) at a volume ratio of 1:0.3-1.5, and under negative pressure conditions, air is used as a stirrer and diluent, the temperature of the reaction liquid is controlled to be 50-80°C, and chlorine dioxide and air are extracted with a water ejector (hydraulic vacuum ejector) and mixed with water to form a high-purity chlorine dioxide disinfectant.

[0055] Preferably, the reaction temperature is controlled at 60-70° C., and the volume ratio of agent A to agent B is 1:0.5-1. The acidity needs to be accurately controlled, because if the acidity is less than 3 moles, the reaction time is long, and if it is higher than 5 moles, the raw material consumption is high and more mother liquor is produced.

[0056] Example 1

[0057] A method for preparing high-purity chlorine dioxide is provided, comprising the following steps:

[0058] Sodium chlorate, hydrogen peroxide, stabilizer and water are prepared to prepare Agent A, wherein the mass percentage of sodium chlorate in Agent A is 40%, the mass percentage of hydrogen peroxide is 6%, the mass percentage of stabilizer is 0.06%, and the rest is water, and the pH value of Agent A is 1. Sulfuric acid, catalyst and water are prepared to prepare Agent B, wherein the mass percentage of sulfuric acid in Agent B is 60%, the mass percentage of catalyst is 0.001%, and the rest is water.

[0059] The stabilizer is a combination of hydroxyethylidene diphosphonic acid (HEDP), sodium diethylenetriamine penta (methylene phosphonic acid) (DTPMP.Na2), and sodium nitrate. In the stabilizer, the proportions of hydroxyethylidene diphosphonic acid (HEDP) and sodium diethylenetriamine penta (methylene phosphonic acid) (DTPMP.Na2) are 10% respectively, and the proportion of sodium nitrate is 80%. The catalyst is a mixture of ruthenium trichloride, palladium dichloride and platinum dichloride, wherein the content of ruthenium trichloride accounts for 0.0004wt% of reagent B, the content of palladium dichloride accounts for 0.0003wt% of reagent B, and the content of platinum dichloride accounts for 0.0003wt% of reagent B.

[0060] Add Agent A and Agent B into a chlorine dioxide generator (or reactor) in a volume ratio of 1:0.5. Under negative pressure conditions, use air as a stirrer and diluent, control the temperature of the reaction liquid to 60°C, use a water ejector (hydraulic vacuum ejector) to extract the chlorine dioxide and air and mix them with water to form a high-purity chlorine dioxide disinfectant.

[0061] Example 2: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that agent A and agent B are added to a chlorine dioxide generator (or reactor) in a volume ratio of 1:0.3, and the remaining steps are the same.

[0062] Example 3: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that agent A and agent B are added to a chlorine dioxide generator (or reactor) in a volume ratio of 1:1.5, and the remaining steps are the same.

[0063] Example 4: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that agent A and agent B are added to a chlorine dioxide generator (or reactor) in a volume ratio of 1:0.2, and the remaining steps are the same.

[0064] Example 5: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that agent A and agent B are added to a chlorine dioxide generator (or reactor) in a volume ratio of 1:2, and the remaining steps are the same.

[0065] Example 6: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the catalyst is ruthenium trichloride, and the remaining steps are the same.

[0066] Example 7: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the catalyst is palladium dichloride, and the remaining steps are the same.

[0067] Embodiment 8: Provided is a method for preparing high-purity chlorine dioxide, which differs from Embodiment 1 in that the catalyst is platinum dichloride, and the remaining steps are the same.

[0068] Example 9: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of hydrogen peroxide in agent A is 4%, and the remaining steps are the same.

[0069] Embodiment 10: Provided is a method for preparing high-purity chlorine dioxide. The difference from Embodiment 1 is that the mass percentage of hydrogen peroxide in Agent A is 8%, and the remaining steps are the same.

[0070] Example 11: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of hydrogen peroxide in agent A is 12%, and the remaining steps are the same.

[0071] Example 12: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of hydrogen peroxide in agent A is 3%, and the remaining steps are the same.

[0072] Example 13: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of hydrogen peroxide in agent A is 15%, and the remaining steps are the same.

[0073] Example 14: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of the stabilizer in Agent A is 0.03%, and the remaining steps are the same.

[0074] Example 15: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of the stabilizer in Agent A is 0.2%, and the remaining steps are the same.

[0075] Example 16: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of the stabilizer in Agent A is 0.3%, and the remaining steps are the same.

[0076] Example 17: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of the stabilizer in Agent A is 0.02%, and the remaining steps are the same.

[0077] Example 18: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the mass percentage of the stabilizer in Agent A is 0.12%, and the remaining steps are the same.

[0078] Example 19: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that potassium chlorate is used as chlorate, and the remaining steps are the same.

[0079] Example 20: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that barium chlorate is used as chlorate, and the remaining steps are the same.

[0080] Example 21: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the temperature of the reaction solution is controlled to 80°C, and the other steps are the same.

[0081] Example 22: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the temperature of the reaction solution is controlled to 60°C, and the other steps are the same.

[0082] Example 23: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the temperature of the reaction solution is controlled to 50°C, and the other steps are the same.

[0083] Implementation Case 24: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the temperature of the reaction solution is controlled at 40°C, and the remaining steps are the same.

[0084] Example 25: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the stabilizer is only hydroxyethylidene diphosphonic acid (HEDP), and the remaining steps are the same.

[0085] Example 26: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the stabilizer is a combination of hydroxyethylidene diphosphonic acid (HEDP) and sodium diethylenetriamine penta (methylene phosphonate) (DTPMP.Na2), each accounting for 50%, and the other steps are the same.

[0086] Example 27: A method for preparing high-purity chlorine dioxide is provided. The difference from Example 1 is that the stabilizer is a combination of hydroxyethylidene diphosphonic acid (HEDP) and sodium nitrate, accounting for 20% and 80% respectively, and the remaining steps are the same.

[0087] Test results

[0088] The chlorine dioxide disinfectant prepared in Examples 1 to 27 was tested. The testing method adopted a five-step iodine titration method to detect the chlorate content in the chlorine dioxide solution. Chlorate conversion rate = (mass of chlorate input - mass of chlorate in chlorine dioxide solution) / mass of chlorate input × 100%, chlorine dioxide purity = (mass of chlorine dioxide in chlorine dioxide solution - mass of chlorine in chlorine dioxide solution) / mass of chlorine dioxide in chlorine dioxide solution × 100%.

[0089] In the embodiment of the present invention, two raw materials are continuously added quantitatively for reaction, and each reaction time is 60 minutes. After each reaction, the chlorine dioxide disinfectant is tested. Table 1 shows the average test results of embodiments 1-27. Figure 1 As shown, the conversion rate of the raw materials in Example 1 is as follows Figure 2 As shown, Figure 1 and Figure 2 All of them are test results of continuous quantitative addition of two raw materials for reaction. Figure 1 The average value of the 8 purity test results was 98.42%. Figure 2 The average value of the 8 raw material conversion rate detection results was 97.05%, and the time for the first reaction to start was 9:00 am.

[0090] The test results of Examples 1 to 27 are shown in Table 1 below:

[0091] Table 1: Test results in disinfectant solution

[0092]

[0093]

[0094] As can be seen from Table 1, by using the preparation method of the embodiment of the present invention to prepare chlorine dioxide, the chlorate conversion rate can be increased to more than 95%, and the purity of chlorine dioxide can be increased to more than 98%.

[0095] Among them, it can be seen from the comparison of Examples 1-5 that when the content of reagent B in the reaction solution is too little, as shown in Example 4, the acidity of the reaction system will be reduced, and the content of sulfuric acid is too little, which greatly reduces the raw material conversion rate; when the content of reagent B in the reaction solution is too much, the raw material conversion rate is not only not obvious, but also leads to over-oxidation, side reactions, and the purity of chlorine dioxide decreases. At the same time, the increase in the amount of sulfuric acid used will lead to an increase in the manufacturing cost of chlorine dioxide and an increase in the amount of residual liquid. When the volume ratio of reagent A to reagent B is 1:0.5-1, not only can the chlorate conversion rate be increased to more than 95%, the purity of chlorine dioxide can be increased to more than 98%, but also the amount of sulfuric acid can be saved, the cost can be reduced, the residual liquid can be reduced, and the environmental protection can be improved.

[0096] By comparing Example 1 and Examples 25-27, it can be seen that when hydroxyethylidene diphosphoric acid (HEDP), hydroxyethylidene diphosphoric acid (HEDP) and sodium diethylenetriamine penta (methylene phosphonate) (DTPMP.Na2) are used in combination as stabilizers, the raw material conversion rate is improved more significantly. Although the use of hydroxyethylidene diphosphoric acid (HEDP) alone, the use of a composition of hydroxyethylidene diphosphoric acid (HEDP) and sodium diethylenetriamine penta (methylene phosphonate) (DTPMP.Na2) and the use of a composition of hydroxyethylidene diphosphoric acid (HEDP) and sodium nitrate as stabilizers can improve the raw material conversion rate to a certain extent, the conversion rates are lower than those of Example 1 of the present invention, and are all lower than 95%. The conversion rate improvement effect of using the composition of hydroxyethylidene diphosphoric acid (HEDP) and sodium diethylenetriamine penta (methylene phosphonate) (DTPMP.Na2) as a stabilizer is higher than the effect of using the composition of hydroxyethylidene diphosphoric acid (HEDP) and sodium nitrate as a stabilizer.

[0097] From the comparison of Example 1 and Examples 6-8, it can be seen that the three catalysts of platinum dichloride, palladium dichloride and ruthenium trichloride can significantly improve the raw material conversion rate, so that the raw material conversion rate reaches more than 95%. However, after the three catalysts are used in combination, the improvement of the raw material conversion rate is more obvious, which can reach more than 96%.

[0098] By comparing Example 1 and Examples 9-13, it can be seen that when the content of hydrogen peroxide is too little, the reaction raw materials will be insufficient, reducing the conversion efficiency of the reaction. As shown in Example 13, when the content of hydrogen peroxide in reagent A exceeds 12%, the conversion rate of the raw materials also decreases. The reason is that the role of hydrogen peroxide in the preparation system is reduction, but hydrogen peroxide has an oxidizing effect. If too much hydrogen peroxide is added, the oxidizing property of the reaction system will increase, thereby reducing the oxidation effect. When the content of hydrogen peroxide in reagent A is in the range of 6 to 8%, the effect is better.

[0099] By comparing Example 1 and Examples 14-18, it can be seen that when the content of the stabilizer is too low, part of the hydrogen peroxide will spontaneously decompose, thereby reducing the raw material conversion rate. When the content of the stabilizer is too high, such as in Example 16, the raw material conversion rate will not be significantly improved, but it will cause a waste of the stabilizer.

[0100] From the comparison among Example 1, Example 19 and Example 20, it can be seen that the use of sodium chlorate, potassium chlorate and barium chlorate as raw materials can increase the chlorate conversion rate to more than 95%, and the purity of chlorine dioxide can be increased to more than 98%.

[0101] It can be seen from Example 1 and Examples 20-24 that too low a reaction temperature will reduce the raw material conversion rate, and a reaction temperature greater than 70°C will produce side reactions, resulting in a decrease in the purity of chlorine dioxide. The optimal reaction temperature is 60-70°C.

[0102] In general, the embodiment of the present invention prepares chlorine dioxide by reacting chlorate with hydrogen peroxide in an acidic medium under the action of a stabilizer and a catalyst, and the raw material conversion rate of the prepared chlorine dioxide can reach more than 95%, and the purity of chlorine dioxide can reach more than 98%. At the same time, the acidity of the reaction medium is reduced to less than 3.5 moles, which reduces the preparation cost of chlorine dioxide by more than 30% and the residual liquid by more than 45% compared with the prior art, and can greatly reduce disinfection by-products, with significant economic and social benefits.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. It should be noted that the structures or components illustrated in the accompanying drawings are not necessarily drawn to scale, and the present invention omits the description of known components and processing technologies and processes to avoid unnecessary limitations on the present invention.

Claims

1. A method for preparing high-purity chlorine dioxide, characterized in that: The method comprises adding reagent A and reagent B into a reaction kettle to react and prepare chlorine dioxide; Wherein, the reagent A comprises chlorate, hydrogen peroxide, a stabilizer and water, and the reagent B comprises sulfuric acid, a catalyst and water.

2. A method for preparing high-purity chlorine dioxide according to claim 1, characterized in that: In the reagent A, the mass percentage of the chlorate is 28-45%, the mass percentage of hydrogen peroxide is 4-12%, the mass percentage of the stabilizer is 0.03-0.2%, and the rest is water; The pH value of the reagent A is 0.5-3.

5.

3. A method for preparing high-purity chlorine dioxide according to claim 2, characterized in that: In the reagent B, the mass percentage of sulfuric acid is 40-75%, the mass percentage of the catalyst is 0.0005-0.002%, and the rest is water.

4. A method for preparing high-purity chlorine dioxide according to claim 3, characterized in that: The volume ratio of the A reagent to the B reagent is 1:0.3-1.

5.

5. A method for preparing high-purity chlorine dioxide according to any one of claims 1 to 4, characterized in that: The stabilizer includes hydroxyethylidene diphosphonic acid and sodium diethylene triamine penta (methylene phosphonate).

6. A method for preparing high-purity chlorine dioxide according to claim 5, characterized in that: The mass fraction of the hydroxyethylidene diphosphonic acid in the stabilizer is 10 to 35%, and the mass fraction of the diethylenetriamine penta (methylene phosphonic acid) sodium in the stabilizer is 10 to 35%; The stabilizer also includes sodium nitrate with a mass fraction of 30 to 80%.

7. A method for preparing high-purity chlorine dioxide according to any one of claims 1 to 4, characterized in that: The catalyst includes at least one of ruthenium trichloride, palladium dichloride and platinum dichloride.

8. A method for preparing high-purity chlorine dioxide according to claim 7, characterized in that: The catalyst comprises ruthenium trichloride, palladium dichloride and platinum dichloride, and the mass ratio is 4:2-4:2-4.

9. A method for preparing high-purity chlorine dioxide according to claim 1, characterized in that: The chlorate includes at least one of sodium chlorate, potassium chlorate and barium chlorate.

10. The method for preparing high-purity chlorine dioxide according to claim 1, characterized in that: The reaction temperature in the reactor is 50-80°C.

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