Preparation method of sodium polyepoxysuccinate
By using organic acid calcium catalysts and polymerization reaction under suitable conditions, the precipitation problem caused by inorganic calcium compounds is solved, and high-polymerization sodium polyepoxysuccinate is obtained, which simplifies the process and improves performance, making it suitable for high-alkalinity water systems.
Patent Information
- Application Number
- CN202510822528.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-19
- Publication Date
- 2025-09-23
AI Technical Summary
The use of inorganic calcium compounds in the existing preparation methods of sodium polyepoxysuccinate leads to precipitation or flocculence, which is complex and costly, and has a low degree of polymerization, affecting performance.
Organic acid calcium is used as a polymerization catalyst, and combined with appropriate temperature and pH value, a small amount of inorganic calcium compound is added to avoid precipitation or flocculants and increase the degree of polymerization to 7-12.
The obtained sodium polyepoxysuccinate does not require purification treatment, has an appropriate degree of polymerization, and has excellent performance. It is suitable for high-alkalinity and high-metal content water systems and has good scale and corrosion inhibition properties.
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Figure BDA0005457056940000071
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of sodium polyepoxysuccinate and relates to a preparation method of sodium polyepoxysuccinate. Background Art
[0002] Sodium polyepoxysuccinate (PESA) is a phosphorus- and nitrogen-free water treatment agent. Its scale inhibition performance is generally superior to that of phosphorus-containing inhibitors, and it exhibits enhanced synergistic effects when combined with phosphates. It also exhibits excellent corrosion inhibition properties, and at high concentrations, it can form a coating on some active metal surfaces, making it an excellent water treatment agent. Furthermore, sodium polyepoxysuccinate is biodegradable and has a wide range of applications, particularly in high-alkalinity, high-metal-content water systems. It is a green, environmentally friendly scale and corrosion inhibitor and detergent with broad application prospects.
[0003] Existing methods for preparing sodium polyepoxysuccinate generally involve the reaction of maleic anhydride with an aqueous sodium hydroxide solution, oxidation to sodium epoxysuccinate under the combined action of a catalyst and hydrogen peroxide, and polymerization of the sodium epoxysuccinate in the presence of calcium hydroxide to form sodium polyepoxysuccinate. Existing methods use a large amount of calcium hydroxide, which has low solubility in water. This results in flocculent matter or precipitates in the polymerized product after the polymerization reaction. Therefore, the calcium hydroxide needs to be removed after the polymerization reaction, for example by sedimentation and filtration, resulting in a complex process and increased costs.
[0004] On the other hand, the average degree of polymerization (DP) significantly impacts the chelation and dispersion properties of sodium polyepoxysuccinate, with a more suitable DP range of 7 to 12. However, the DP of currently prepared sodium polyepoxysuccinate is relatively low, with a higher proportion of DPs between 3 and 6.
[0005] Therefore, the above-mentioned problems need to be solved urgently. Summary of the Invention
[0006] In order to solve the above technical problems, the present invention provides a method for preparing sodium polyepoxysuccinate.
[0007] The technical solutions of the present invention are as follows:
[0008] A method for preparing polysodium epoxysuccinate, which is prepared by polymerization reaction of sodium epoxysuccinate;
[0009] At least 50% by weight of the polymerization catalyst used in the polymerization reaction is organic acid calcium.
[0010] Preferably, at least 70% by weight of the polymerization catalyst is calcium organic acid.
[0011] Preferably, the organic acid calcium is selected from C1-C4 aliphatic organic acid calcium and hydrates thereof.
[0012] More preferably, the organic acid calcium is selected from one or a combination of two or more of calcium formate, calcium acetate, calcium acetate monohydrate, calcium acetate dihydrate, calcium propionate, calcium butyrate and calcium butyrate monohydrate.
[0013] Preferably, the polymerization reaction temperature is 85-105° C., and the pH is not lower than 11.
[0014] Preferably, the weight ratio of the polymerization catalyst to the sodium epoxysuccinate is 5-12:100.
[0015] Preferably, the polymerization catalyst further contains an inorganic calcium compound, and the weight proportion of the inorganic calcium compound in the polymerization catalyst is not higher than 30%;
[0016] The inorganic calcium compound is selected from one or a combination of two or more of calcium hydroxide, calcium sulfate, calcium oxide and calcium chloride.
[0017] Preferably, the sodium epoxysuccinate is obtained by reacting maleic anhydride with NaOH and then performing an oxidation reaction.
[0018] More preferably, the maleic anhydride is pre-dissolved in water and then reacted with the NaOH.
[0019] Preferably, the oxidation reaction uses sodium tungstate dihydrate as an oxidation reaction catalyst and hydrogen peroxide with a concentration of 20-50wt% as an oxidant.
[0020] The beneficial effects of the present invention are:
[0021] (1) The sodium epoxysuccinate polymerization catalyst of the present invention contains an organic acid calcium, and is found to produce no precipitation or flocculants. Therefore, the product obtained by the polymerization reaction does not require any impurity removal or purification steps and can be used directly. Furthermore, the obtained polysodium epoxysuccinate has a high degree of polymerization (n) of 7-12, resulting in a better effect.
[0022] (2) The polymerization catalyst contains a certain amount of inorganic calcium compound, which can further increase the reaction rate and shorten the reaction time. In addition, a small amount of inorganic calcium compound will not cause precipitation or flocculants after the polymerization reaction. DETAILED DESCRIPTION
[0023] The technical solution of the present invention is further illustrated and described below through specific implementation methods.
[0024] The present invention provides a method for preparing polysodium epoxysuccinate, which is prepared by polymerization reaction of sodium epoxysuccinate;
[0025] At least 50% by weight of the polymerization catalyst used in the above polymerization reaction is organic acid calcium.
[0026] In the prior art, inorganic calcium compounds are generally used as catalysts for preparing polysodium epoxysuccinate by the polymerization reaction of sodium epoxysuccinate. Inorganic calcium compounds include calcium hydroxide, calcium sulfate, calcium oxide, calcium chloride, etc. However, the solubility of inorganic calcium compounds in water is low. After the polymerization reaction, some inorganic calcium compounds will precipitate or precipitate from the polymer product. The solution after polymerization must be purified, such as by filtering and removing impurities, which prolongs the process and requires more equipment, which is not conducive to mass production. The polymerization reaction catalyst of the present invention comprises organic acid calcium, which solves the above problems. That is, after the polymerization reaction, the organic acid calcium will not precipitate or precipitate, and no other products or raw materials will precipitate or precipitate. The solution after the polymerization reaction can be used directly without purification, filtration, etc. For example, the weight content of organic acid calcium in the polymerization catalyst can be any value among 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, etc. or any value therebetween. Furthermore, at least 70% by weight of the polymerization catalyst is organic acid calcium.
[0027] In some embodiments, the organic acid calcium is selected from C1-C4 aliphatic organic acid calcium and hydrates thereof. Furthermore, the organic acid calcium is selected from one or a combination of two or more of calcium formate, calcium acetate, calcium acetate monohydrate, calcium acetate dihydrate, calcium propionate, calcium butyrate, and calcium butyrate monohydrate. Organic acid calcium, taking calcium acetate as an example, has a high solubility in water, with a solubility of approximately 34 g / 100 ml at 20°C, which can avoid precipitation or separation similar to calcium hydroxide after the polymerization reaction.
[0028] In some embodiments, the polymerization reaction temperature is 85-105°C, and the pH is not less than 11. The present invention has found that the use of the polymerization catalyst of the present invention requires a relatively higher temperature and a higher pH, otherwise it is not conducive to the polymerization reaction. The relatively higher temperature can also inhibit the esterification reaction between the carboxylate group and the epoxy group in the organic acid calcium; if the polymerization reaction temperature is not enough, such as 80°C, the polymerization effect is poor, the average degree of polymerization of the product sodium polyepoxysuccinate will be low, and the performance of the sodium polyepoxysuccinate is poor. The polymerization reaction temperature can be 85°C, 90°C, 95°C, 100°C, 105°C, etc.; the polymerization reaction pH can be 11, 11.5, 12, 12.5, 13, etc.
[0029] In some embodiments, the weight ratio of the polymerization catalyst to sodium epoxysuccinate is 5-12:100. For example, the weight ratio can be any value among 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, or any value in between. Insufficient amounts of polymerization catalyst, such as 3:100, can result in a slow polymerization rate or incomplete polymerization. Excessive amounts of polymerization catalyst are economically disadvantageous and hinder control of the polymerization process. The weight of sodium epoxysuccinate can be calculated based on the weight of maleic anhydride added. Theoretically, 1 mol of maleic anhydride is converted into 1 mol of sodium epoxysuccinate.
[0030] In some embodiments, the polymerization catalyst further contains an inorganic calcium compound, and the weight proportion of the inorganic calcium compound in the polymerization catalyst is no more than 30%;
[0031] The inorganic calcium compound is selected from one or a combination of two or more of calcium hydroxide, calcium sulfate, calcium oxide and calcium chloride.
[0032] Furthermore, the weight proportion of the inorganic calcium compound in the polymerization catalyst is no more than 20%, or no more than 10%.
[0033] Adding a portion of the inorganic calcium compound to the polymerization catalyst of the present invention can accelerate the polymerization reaction rate, shorten the polymerization reaction time, and improve production efficiency. Moreover, since the amount of the inorganic calcium compound added is relatively small, precipitation or flocculants will not form in the polymerized product, thus avoiding the need for filtration and impurity removal processes after the polymerization reaction.
[0034] In some embodiments, sodium epoxysuccinate is obtained by reacting maleic anhydride with NaOH followed by oxidation.
[0035] In some embodiments, maleic anhydride is pre-dissolved in water before reacting with NaOH. Pre-dissolving maleic anhydride in water allows for initial ring-opening to generate butenedioic acid, releasing some heat. Then, the butenedioic acid is neutralized by the addition of an aqueous NaOH solution, further releasing some heat. This gradual heat release avoids concentrated heat release that could lead to excessive temperature increases in the reaction system. In actual production, a cooling kettle can be omitted, saving costs.
[0036] In some embodiments, the oxidation reaction uses sodium tungstate dihydrate as an oxidation reaction catalyst and 20-50 wt% hydrogen peroxide as an oxidant. The weight of sodium tungstate dihydrate can be 2-8% of the weight of maleic anhydride. The weight of hydrogen peroxide can be 0.8-1.5 times the weight of maleic anhydride.
[0037] For the preparation method of sodium polyepoxysuccinate, starting from maleic anhydride, the steps can be as follows:
[0038] S1, maleic anhydride and deionized water are added to a reactor and stirred at room temperature until the maleic anhydride is dissolved; the weight ratio of maleic anhydride to deionized water can be 1:1.5-1.8;
[0039] S2. Slowly add NaOH solution dropwise under stirring, and vacuum concentrate until the solution is saturated; during the addition of NaOH solution, control the temperature of the reaction system to not more than 50°C and the pH to 5-6; during vacuum concentration, the temperature of the reaction system can be controlled at 60-65°C;
[0040] S3. Sodium tungstate dihydrate is added to the saturated solution, stirred and dissolved, hydrogen peroxide solution is slowly added dropwise, and NaOH solution is simultaneously added dropwise to control the pH of the reaction system to 4.5-6. After the addition is completed, an oxidation reaction is carried out. After the oxidation reaction is completed, secondary concentration is performed to adjust the solid content to ≥45%; the oxidation reaction temperature can be 65-80°C, and the reaction time can be 6-24h;
[0041] S4, add polymerization catalyst, and adjust pH value to not less than 11 with NaOH solution, carry out polymerization reaction, namely obtain clear and transparent sodium polyepoxysuccinate solution.The polymerization reaction time can be 2-12h, can be adjusted according to polymerization catalyst dosage, polymerization reaction temperature, pH etc., this is well known to those skilled in the art.
[0042] The technical solution of the present invention is further described and illustrated below based on various embodiments. Unless otherwise specified, the parts in the following embodiments are parts by weight.
[0043] Example 1
[0044] Add 98 g of maleic anhydride and 147 g of deionized water to a 1 L three-necked flask and stir at room temperature for 0.5 h. Slowly add 272 g of a 25 wt% NaOH aqueous solution dropwise while stirring. Control the reaction system temperature to <50°C and the pH to 5-6. After the addition is complete, set the temperature to 65°C and concentrate under vacuum until the solution is saturated.
[0045] Add 2.71g of sodium tungstate dihydrate to the saturated solution and stir for 10 minutes. Then, slowly add 102g of 50wt% hydrogen peroxide solution dropwise over 1.5 hours. Simultaneously, add 48g of 25wt% aqueous NaOH solution dropwise while controlling the reaction system's pH to 4.5-5.5 and the temperature to ≤75°C. After the addition is complete, maintain the reaction at 75°C for 8 hours. After the reaction is complete, perform a second vacuum dehydration to obtain a sodium epoxysuccinate solution with a solids content of 46.7wt%.
[0046] The sodium epoxysuccinate solution was heated to 85° C., 14.5 g of calcium acetate monohydrate was added, and the mixture was stirred for 5 min. Then, 26.5 g of a 25 wt % NaOH aqueous solution was added to adjust the pH of the reaction system to 11.5-12. The polymerization reaction was carried out for 3 h to obtain a transparent light yellow polysodium epoxysuccinate solution without flocculation and / or precipitation.
[0047] Example 2
[0048] This Example differs from Example 1 in that, in Example 1, the amount of calcium acetate monohydrate was adjusted from 14.5 g to 10 g, and the polymerization reaction time was adjusted from 3 hours to 6 hours. The remaining steps remained unchanged. In this Example, it was found that as the amount of polymerization catalyst was reduced, the polymerization reaction time needed to be extended; otherwise, the sodium epoxysuccinate reaction was incomplete. The resulting sodium polyepoxysuccinate solution was a transparent, pale yellowish solution.
[0049] Comparative Example 1
[0050] The differences between this comparative example and Example 1 are as follows: in Example 1, the amount of calcium acetate monohydrate was adjusted from 14.5 g to 7 g, and the polymerization reaction time was adjusted from 3 h to 14 h. The remaining steps remained unchanged. The resulting sodium polyepoxysuccinate solution was transparent and light yellow.
[0051] Comparative Example 2
[0052] The difference between this comparative example and comparative example 1 is that in comparative example 1, the polymerization reaction temperature was adjusted from 85° C. to 105° C. The remaining steps remained unchanged. The obtained sodium polyepoxysuccinate solution was transparent and light yellow.
[0053] Comparative Example 3
[0054] The difference between this comparative example and Example 1 is that in Example 1, the polymerization reaction temperature of the sodium epoxysuccinate solution was adjusted from 85° C. to 80° C. The remaining steps remained unchanged. The obtained sodium epoxysuccinate solution was transparent and light yellow.
[0055] Example 3
[0056] This example differs from Example 1 in that the polymerization catalyst in Example 1 was adjusted from 14.5 g of calcium acetate monohydrate to a combination of 13.5 g of calcium acetate monohydrate and 1 g of calcium hydroxide. The remaining steps remained unchanged. The resulting sodium polyepoxysuccinate solution was a transparent, pale yellow solution.
[0057] Example 4
[0058] This example differs from Example 1 in that the polymerization catalyst in Example 1 was adjusted from 14.5 g of calcium acetate monohydrate to a combination of 10 g of calcium acetate monohydrate and 4.5 g of calcium formate. The remaining steps remained unchanged. The resulting sodium polyepoxysuccinate solution was a transparent, pale yellow solution.
[0059] Example 5
[0060] This example differs from Example 1 in that the polymerization catalyst in Example 1 was adjusted from 14.5 g of calcium acetate monohydrate to 20 g of calcium acetate monohydrate. The remaining steps remained unchanged. The resulting sodium polyepoxysuccinate solution was transparent and light yellow.
[0061] Example 6
[0062] The difference between this example and Example 1 is that in Example 1, the polymerization reaction temperature of the sodium epoxysuccinate solution was adjusted from 85° C. to 105° C. The remaining steps remained unchanged. The obtained sodium epoxysuccinate solution was transparent and light yellow.
[0063] Performance Testing
[0064] Degree of polymerization: tested by gel permeation chromatography (GPC).
[0065] Scale inhibition rate: The scale inhibition rate for brass was tested according to GB / T 16632-2019, "Determination of scale inhibition performance of water treatment agents - Calcium carbonate deposition method." The concentrations of sodium polyepoxysuccinate were 10 mg / L and 15 mg / L, respectively.
[0066] The results are shown in Table 1 below.
[0067] Table 1
[0068]
[0069] Therefore, the data in Table 1 above show that the degree of polymerization n of the sodium polyepoxysuccinate obtained in the present invention is the highest in the range of 7-12, which can fully exert the chelating and dispersing effects of the sodium polyepoxysuccinate and has a good scale inhibition effect.
[0070] As described above, the basic principles, main features, and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments. The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. In other words, equivalent changes and modifications made within the scope of the present invention and the contents of the specification should still fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing sodium polyepoxysuccinate, characterized in that: Prepared by polymerization reaction of sodium epoxysuccinate; At least 50% by weight of the polymerization catalyst used in the polymerization reaction is organic acid calcium.
2. The preparation method of polyepoxy sodium succinate according to claim 1, wherein At least 70% by weight of the polymerization catalyst is calcium organic acid.
3. The preparation method of polyepoxy sodium succinate according to claim 1 or 2, wherein The organic acid calcium is selected from C1-C4 aliphatic organic acid calcium and hydrates thereof.
4. The preparation method of polyepoxy sodium succinate according to claim 3, wherein The organic acid calcium is selected from one or a combination of two or more of calcium formate, calcium acetate, calcium acetate monohydrate, calcium acetate dihydrate, calcium propionate, calcium butyrate and calcium butyrate monohydrate.
5. The preparation method of polyepoxy sodium succinate according to claim 1, wherein The polymerization reaction temperature is 85-105° C., and the pH is not lower than 11.
6. The preparation method of polyepoxy sodium succinate according to claim 1, wherein The weight ratio of the polymerization catalyst to the sodium epoxysuccinate is 5-12:
100.
7. The preparation method of polyepoxy sodium succinate according to claim 1, wherein The polymerization catalyst further contains an inorganic calcium compound, and the weight proportion of the inorganic calcium compound in the polymerization catalyst is not higher than 30%; The inorganic calcium compound is selected from one or a combination of two or more of calcium hydroxide, calcium sulfate, calcium oxide and calcium chloride.
8. The preparation method of polyepoxy sodium succinate according to claim 1, wherein The sodium epoxysuccinate is obtained by reacting maleic anhydride with NaOH and then performing an oxidation reaction.
9. The preparation method of polyepoxy sodium succinate according to claim 8, wherein The maleic anhydride is pre-dissolved in water and then reacted with the NaOH.
10. The method for preparing polyepoxy sodium succinate according to claim 8, wherein The oxidation reaction uses sodium tungstate dihydrate as an oxidation reaction catalyst and hydrogen peroxide with a concentration of 20-50wt% as an oxidant.