A catalyst system for synthesizing sodium epoxysuccinate and its application

Abstract

The invention discloses a catalyst system for synthesizing sodium epoxysuccinate, which is composed of a main catalyst and a co-catalyst, wherein the main catalyst is sodium tungstate, and the co-catalyst is Q3PW4O 24 , Q is tetradecylpyridine. The catalyst system for synthesizing sodium epoxysuccinate can improve the reaction selectivity and effectively inhibit the side reaction when used to synthesize sodium epoxysuccinate, so that the scale inhibition rate of the polyepoxysuccinic acid prepared from the sodium epoxysuccinate is significantly improved. The present invention also discloses an application of the catalyst system for synthesizing sodium epoxysuccinate in synthesizing sodium epoxysuccinate.

Description

Technical Field

[0001] The invention relates to a catalyst for synthesizing sodium epoxysuccinate, in particular to a catalyst system for synthesizing sodium epoxysuccinate and application thereof. Background Art

[0002] Polyepoxysuccinic acid (PESA) is a green corrosion and scale inhibitor with the characteristics of being phosphorus-free, nitrogen-free, and biodegradable, and suitable for high-alkali and high-solid water systems. Inserting oxygen atoms into the molecules of polymaleic acid scale inhibitors makes it have good scale inhibition performance, strong chelating power for calcium, magnesium, iron and other ions, and phosphorus-free, nitrogen-free, and easily biodegradable. It is suitable for high-alkali and high-solid water systems and can be used for boiler water treatment, cooling water treatment, sewage treatment, seawater desalination, membrane separation, etc. Its scale inhibition and corrosion inhibition performance are significantly better than sodium polyacrylate, polymaleic acid, and tartaric acid.

[0003] The method for preparing polyepoxysuccinic acid sodium salt reported in China is: first, hydrolyze maleic anhydride under alkaline conditions, that is, dissolve maleic anhydride in water, slowly add sodium hydroxide aqueous solution under stirring for hydrolysis; use sodium tungstate as a catalyst, add quantitative hydrogen peroxide at a controlled speed at a certain temperature to the hydrolysis product, and use sodium hydroxide to control the pH value of the solution and keep it for a certain time to make it fully react, so as to obtain the intermediate product sodium epoxysuccinate, so this process is called epoxidation process. The epoxidation process is complex to control and easily generates by-products, which leads to reduced product quality. It is the most important step in the entire production process.

[0004] The double bonds in maleic anhydride, the raw material of sodium epoxysuccinate, are of a type with poor activity, so epoxidation cannot be achieved in an acidic catalytic system, so the traditional catalytic reaction selects the alkaline catalyst sodium tungstate. However, hydrogen peroxide is easy to self-decompose in an alkaline catalytic system to produce side reactions. The heat release of this side reaction not only makes it difficult to control the reaction heat of the overall reaction process (the process conditions are difficult to control), but also promotes the hydrolysis of sodium epoxysuccinate to generate tartaric acid as a byproduct (low reaction selectivity).

[0005] Therefore, it is necessary to develop a catalyst system for synthesizing sodium epoxysuccinate which can improve reaction selectivity and effectively inhibit side reactions. Summary of the invention

[0006] The purpose of the present invention is to provide a catalyst system for synthesizing sodium epoxysuccinate which can improve reaction selectivity and effectively inhibit side reactions.

[0007] The invention also provides application of a catalyst system for synthesizing sodium epoxysuccinate in synthesizing sodium epoxysuccinate.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme: a catalyst system for synthesizing sodium epoxysuccinate of the present invention, the catalyst system for synthesizing sodium epoxysuccinate is composed of a main catalyst and a co-catalyst, the main catalyst is sodium tungstate, and the co-catalyst is Q3PW4O 24 , Q is tetradecylpyridine. The inventor accidentally discovered in the experiment that the main catalyst sodium tungstate and Q3PW4O 24 (Q is tetradecylpyridine) is compounded in a specific ratio to form a catalytic system and applied to the synthesis reaction of sodium epoxysuccinate, which can improve the reaction selectivity and effectively inhibit side reactions, so that the scale inhibition rate of polyepoxysuccinic acid prepared from the sodium epoxysuccinate is significantly improved.

[0009] Preferably, in the catalyst system for synthesizing sodium epoxysuccinate, the mass ratio of the co-catalyst to the main catalyst is (0.04-0.10): 1. The inventors found in the experiment that only after the co-catalyst and the main catalyst are compounded in a specific mass ratio, i.e., (0.04-0.10): 1, can the reaction selectivity be improved and the side reactions be effectively inhibited. The mechanism may be that a specific amount of the co-catalyst can quickly activate hydrogen peroxide and inhibit the self-decomposition of hydrogen peroxide, thereby effectively controlling the side reactions of the system. At the same time, the activated species forms highly active oxygen anions under the action of the main catalyst to attack the low-activity acid anhydride double bonds to complete the epoxidation process; if the content of the co-catalyst is too high, it will not have a better effect on improving the reaction performance, and will increase the production cost; and if the content of the co-catalyst is too low, the desired catalytic effect cannot be achieved.

[0010] The invention discloses an application of a catalyst system for synthesizing sodium epoxysuccinate. The specific application method is as follows: adding water and maleic anhydride into a reaction kettle, heating to dissolve the maleic anhydride, dripping a sodium hydroxide solution under stirring, controlling the reaction temperature within 70 DEG C, and obtaining a hydrolysis product after the reaction; adding the catalyst system into the hydrolysis product, gradually dripping hydrogen peroxide after the catalyst system is completely dissolved, controlling the kettle temperature within 60-70 DEG C, gradually dripping hydrogen peroxide to control the pH value within 5.0-6.0, and after the dripping of hydrogen peroxide is completed, maintaining the temperature at 60-70 DEG C for epoxidation reaction, and obtaining sodium epoxysuccinate after the reaction is completed.

[0011] Preferably, the mass ratio of water to maleic anhydride is 1:1.

[0012] Preferably, heating to 40°C is performed to dissolve the maleic anhydride.

[0013] Preferably, during the hydrolysis reaction, the sodium hydroxide solution is added dropwise within 0.5 to 1 hour, the mass concentration of the sodium hydroxide solution is 50%, and the mass ratio of the sodium hydroxide solution to maleic anhydride is 1.25:1.

[0014] Preferably, the amount of the catalyst system added is 3.0-5.0% of the mass of maleic anhydride.

[0015] Preferably, hydrogen peroxide with a mass concentration of 35% is gradually added dropwise, and the mass ratio of hydrogen peroxide to maleic anhydride is (1.00-1.25):1.

[0016] Preferably, the pH value is controlled to be between 5.0 and 6.0 by dripping a sodium hydroxide solution having a mass concentration of 50%.

[0017] Preferably, after the addition of hydrogen peroxide is completed, the kettle temperature is controlled at 60-65° C. and kept warm for 2 hours to carry out the epoxidation reaction.

[0018] Therefore, the present invention has the following beneficial effects: a catalyst system for synthesizing sodium epoxysuccinate is designed, which can improve the reaction selectivity and effectively inhibit side reactions when used to synthesize sodium epoxysuccinate, so that the scale inhibition rate of polyepoxysuccinic acid prepared from the sodium epoxysuccinate is significantly improved. DETAILED DESCRIPTION

[0019] The present invention is further described below through specific implementation modes.

[0020] Example 1

[0021] 200g of water and 200g of maleic anhydride were added to a 2L reactor, heated to 40°C to dissolve the maleic anhydride, and then 245g of a 50% sodium hydroxide solution was added dropwise under stirring, and the reaction temperature was controlled at 65°C to obtain a hydrolysis product after the reaction; a catalyst system was added to the hydrolysis product, the catalyst system consisting of a main catalyst and a co-catalyst, the main catalyst being sodium tungstate, and the co-catalyst being Q3PW4O 24 , Q is tetradecylpyridine, the amount of the catalyst system added is 3.6% (7.2g) of the mass of maleic anhydride, the mass ratio of the co-catalyst to the main catalyst is 5:52 (i.e. 6.57g of the main catalyst and 0.63g of the co-catalyst); after the catalyst system is completely dissolved, 240g of 35% hydrogen peroxide is gradually added dropwise, the kettle temperature is controlled at 65°C, and the pH value is controlled at 6.0 by adding 50% sodium hydroxide solution dropwise. After the addition of hydrogen peroxide is completed, the epoxy reaction is carried out at 65°C for 2h. After the reaction is completed, sodium epoxysuccinate is obtained.

[0022] Comparative Example 1

[0023] The difference between Comparative Example 1 and Example 1 is that no co-catalyst is added, and the co-catalyst is replaced by the main catalyst of the same mass (ie, the main catalyst is 7.2 g), and the rest is the same as Example 1.

[0024] Comparative Example 2

[0025] The difference between Comparative Example 2 and Example 1 is that no main catalyst is added, and the main catalyst is replaced by a co-catalyst of the same mass (ie, the co-catalyst is 7.2 g), and the rest is the same as Example 1.

[0026] Comparative Example 3

[0027] Compared with Example 1, Comparative Example 3 is different in that the mass ratio of the co-catalyst to the main catalyst is 0.02:1, and the rest is the same as Example 1.

[0028] Comparative Example 4

[0029] Compared with Example 1, Comparative Example 4 is different in that the mass ratio of the co-catalyst to the main catalyst is 0.12:1, and the rest is the same as Example 1.

[0030] Comparative Example 5

[0031] Comparative Example 5 is different from Example 1 in that the co-catalyst is Q3PW4O 24 , Q is trimethylpyridine, and the rest is the same as in Example 1.

[0032] Comparative Example 6

[0033] Comparative Example 6 is different from Example 1 in that the co-catalyst is Q3PW4O 24 , Q is dodecylpyridine, and the rest is the same as in Example 1.

[0034] Comparative Example 7

[0035] Comparative Example 7 is different from Example 1 in that the co-catalyst is Q3PW4O 24 , Q is hexadecylpyridine, and the rest is the same as in Example 1.

[0036] Comparative Example 8

[0037] Compared with Example 1, Comparative Example 8 is different in that the amount of the catalyst system added is 2.5% of the mass of maleic anhydride, and the rest is the same as Example 1.

[0038] Comparative Example 9

[0039] Compared with Example 1, Comparative Example 9 is different in that the amount of the catalyst system added is 5.5% of the mass of maleic anhydride, and the rest is the same as Example 1.

[0040] Example 2

[0041] Compared with Example 1, Example 2 is different in that the amount of the catalyst system added is 3.0% of the mass of maleic anhydride, and the rest is exactly the same as Example 1.

[0042] Example 3

[0043] Compared with Example 1, Example 3 is different in that the amount of the catalyst system added is 5.0% of the mass of maleic anhydride, and the rest is exactly the same as Example 1.

[0044] Example 4

[0045] Compared with Example 1, Example 4 is different in that the mass ratio of the co-catalyst to the main catalyst is 0.04:1, and the rest is exactly the same as Example 1.

[0046] Example 5

[0047] Compared with Example 1, Example 5 is different in that the mass ratio of the co-catalyst to the main catalyst is 0.10:1, and the rest is exactly the same as Example 1.

[0048] The sodium epoxysuccinate prepared in the above-mentioned embodiments and comparative examples is further subjected to polymerization reaction to obtain sodium polyepoxysuccinate. The specific method is as follows: the reaction kettle is cooled to below 40°C, the pH value of the reaction solution is adjusted to 9.0 with a NaOH solution to decompose the excess hydrogen peroxide in the reaction solution, the mixture is stirred and the temperature is raised, a polymerization initiator Ca(OH)2 is added, the reaction temperature is controlled to 95°C and kept warm for 2.5 hours, and sodium polyepoxysuccinate is obtained after the reaction is completed. After the product temperature drops below 40°C, the sodium polyepoxysuccinate product is packaged, labeled and sampled for analysis. The analysis results are shown in Table 1.

[0049] Table 1 Properties of the sodium epoxysuccinate prepared in each embodiment and comparative example and the sodium polyepoxysuccinate synthesized therefrom

[0050]

[0051]

[0052] (1) Epoxysuccinic acid selectivity = weight of epoxysuccinate / total weight of sample × 100%;

[0053] (2) The scale inhibition rate of sodium polyepoxysuccinate sample was determined according to “GB / T16632-2008 Determination of scale inhibition performance of water treatment agents - Calcium carbonate precipitation method”.

[0054] It can be seen from Table 1 that a small amount (3.0-5.0%) of co-catalyst Q3PW4O is added to the catalyst system. 24 (Q is tetradecylpyridine), the catalyst performance, especially the scale inhibition rate, was significantly improved; while the addition of other co-catalysts of this type did not significantly improve the scale inhibition rate of the product; this shows that the addition of the main catalyst sodium tungstate and Q3PW4O 24(Q is tetradecylpyridine) is compounded in a specific ratio to form a catalytic system and applied to the synthesis reaction of sodium epoxysuccinate, which can improve the reaction selectivity and effectively inhibit side reactions, thereby improving the scale inhibition rate of the polyepoxysuccinate prepared from the sodium epoxysuccinate.

[0055] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A catalyst system for synthesizing sodium epoxysuccinate, characterized in that: The catalyst system for synthesizing sodium epoxysuccinate is composed of a main catalyst and a co-catalyst, wherein the main catalyst is sodium tungstate and the co-catalyst is Q3PW4O 24 , Q is tetradecylpyridine, and in the catalyst system for synthesizing sodium epoxysuccinate, the mass ratio of the co-catalyst to the main catalyst is (0.04~0.10):

1.

2. Use of the catalyst system for synthesizing sodium epoxysuccinate as claimed in claim 1 in synthesizing sodium epoxysuccinate, characterized in that: The specific application method is as follows: add water and maleic anhydride into a reaction kettle, heat to dissolve the maleic anhydride, then dropwise add sodium hydroxide solution under stirring, control the reaction temperature within 70°C, and obtain a hydrolysis product after the reaction; Add the catalyst system to the hydrolyzate, and after the catalyst system is completely dissolved, gradually add hydrogen peroxide and control the kettle temperature at 60-70°C, and at the same time control the pH value at 5.0-6.

0. After the addition of hydrogen peroxide is completed, keep the temperature at 60-70°C to allow the epoxidation reaction to proceed completely. After the reaction is completed, sodium epoxysuccinate is obtained.

3. The use of the catalyst system for synthesizing sodium epoxysuccinate according to claim 2 in synthesizing sodium epoxysuccinate, characterized in that: The mass ratio of water to maleic anhydride is 1:

1.

4. The use of the catalyst system for synthesizing sodium epoxysuccinate according to claim 2 in synthesizing sodium epoxysuccinate, characterized in that: Heat to 40°C to dissolve the maleic anhydride.

5. The use of the catalyst system for synthesizing sodium epoxysuccinate according to claim 2 in synthesizing sodium epoxysuccinate, characterized in that: During the hydrolysis reaction, the sodium hydroxide solution is added dropwise within 0.5 to 1 hour, the mass concentration of the sodium hydroxide solution is 50%, and the mass ratio of the sodium hydroxide solution to maleic anhydride is 1.25:

1.

6. Use of the catalyst system for synthesizing sodium epoxysuccinate according to claim 2 in synthesizing sodium epoxysuccinate, characterized in that: The amount of catalyst system added is 3.0-5.0% of the mass of maleic anhydride.

7. Use of the catalyst system for synthesizing sodium epoxysuccinate according to claim 2 in synthesizing sodium epoxysuccinate, characterized in that: Gradually add hydrogen peroxide with a mass concentration of 35%, and the mass ratio of hydrogen peroxide to maleic anhydride is (1.00~1.25):

1.

8. Use of the catalyst system for synthesizing sodium epoxysuccinate according to claim 2 in synthesizing sodium epoxysuccinate, characterized in that: The pH value was controlled at 5.0-6.0 by dropping a 50% sodium hydroxide solution.

9. Use of the catalyst system for synthesizing sodium epoxysuccinate according to claim 2 in synthesizing sodium epoxysuccinate, characterized in that: After the addition of hydrogen peroxide is completed, the kettle temperature is controlled at 60~65℃; keep it warm for 2 hours to carry out the epoxidation reaction.

Images