Sodium beta-naphthalene sulfonate formaldehyde condensate and method for preparing the same

Abstract

The present application relates to the chemical technology field, specifically to a kind of β-naphthalenesulfonic acid sodium formaldehyde condensate and preparation method thereof, the preparation method is prepared naphthalenesulfonic acid mixture with naphthalene and sulfuric acid as raw material, β-naphthalenesulfonic acid in naphthalenesulfonic acid mixture is extracted by melt crystallization, β-naphthalenesulfonic acid is sequentially subjected to condensation reaction, neutralization reaction and purification step, and β-naphthalenesulfonic acid sodium formaldehyde condensate is obtained.The present application extracts β-naphthalenesulfonic acid from naphthalenesulfonic acid mixture by melt crystallization method, which has high purity and high yield, and avoids removing α-naphthalenesulfonic acid by hydrolysis reaction and recycling the generated naphthalene, without using lime for impurity removal, thereby avoiding the introduction of calcium and magnesium ions and other impurities.The operation steps of the present application for preparing β-naphthalenesulfonic acid sodium formaldehyde condensate are simpler than traditional methods, and the product quality and economy of β-naphthalenesulfonic acid sodium formaldehyde condensate are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical technology field, and in particular to a kind of β-naphthalenesulfonic acid sodium formaldehyde condensate and preparation method thereof. BACKGROUND

[0002] Naphthalenesulfonic acid sodium formaldehyde condensate is an anionic surfactant, which is a powder solid, stable in chemical properties, easily soluble in water, has good emulsification, dispersion, wetting and penetration properties, and can be compounded with various dispersants, so it is widely used in water-soluble dyes, fiber softener and water treatment agent fields. As a water treatment agent, naphthalenesulfonic acid sodium formaldehyde condensate can play the dual role of precipitant and complexing agent, improve the transparency and quality of water; as a dye, it can enhance the hydrophilicity, dispersibility and dyeing effect of the dye, making the dyeing fast, uniform and durable; as a fiber softener, it can enhance the hydrophilicity of the softener and improve the softness and gloss of the fiber material. In addition, naphthalenesulfonic acid sodium formaldehyde condensate diluent can be used in papermaking industry slurry control to reduce the two-sidedness, adjust the retention rate of fine fibers, and reduce the coating viscosity.

[0003] Naphthalenesulfonic acid sodium formaldehyde condensate is also widely used in leather, pesticides, building concrete and other fields, for example: as a tanning agent for leather, a spreading agent and a filler for pesticides, a water-reducing agent for cement concrete and oil well cement, etc. It can also be used as a high-efficiency dispersant for water-based paint and pigment paste, and as an adhesive to become a filling powder for polymers to improve the water resistance of materials in the sealing layer. Naphthalenesulfonic acid sodium formaldehyde condensate has many excellent properties and is an important part of organic synthesis.

[0004] β-naphthalenesulfonic acid sodium formaldehyde condensate is a commonly used naphthalenesulfonic acid sodium formaldehyde condensate. The traditional preparation method is as follows: a mixture of α-naphthalenesulfonic acid and β-naphthalenesulfonic acid is obtained by sulfonation with concentrated sulfuric acid and naphthalene as raw materials, α-naphthalenesulfonic acid is removed by hydrolysis, and then β-naphthalenesulfonic acid is condensed with formaldehyde, excess sulfuric acid is removed with lime, and β-naphthalenesulfonic acid sodium formaldehyde condensate is obtained by neutralization with sodium hydroxide. The disadvantage of this preparation method is that when preparing the intermediate product β-naphthalenesulfonic acid, α-naphthalenesulfonic acid needs to be removed by hydrolysis and the generated naphthalene needs to be recovered, which will produce a large amount of sulfuric acid. Therefore, cheap lime is needed to neutralize the sulfuric acid, and excess sulfuric acid is removed in the form of calcium sulfate. However, calcium sulfate has strong adsorption capacity for the product, which will cause the loss of the product. Moreover, the neutralization process will introduce calcium and magnesium ions (impurities) to reduce the quality of the final product. The preparation method is complex, the product purity is not high, and the yield is low.

[0005] To this end, as disclosed in a preparation method of high-concentration naphthalene sulfonic acid formaldehyde condensate in patent CN107674005A, water-carrying agent is added in the sulfonation reaction process to carry out acid water, so as to reduce the amount of lye and lime in the neutralization process, however, the water-carrying agent can only form azeotrope with water and cannot carry out a large amount of sulfuric acid, and lime is still used in the neutralization process, which still introduces calcium and magnesium ions, and cannot further improve the purity of naphthalene sulfonic acid formaldehyde condensate. As disclosed in a preparation method of naphthalene sulfonic acid sodium formaldehyde condensate in patent CN102070495A, it is attempted to selectively neutralize naphthalene sulfonic acid by using the acid difference between naphthalene sulfonic acid and sulfuric acid, so that it does not react with sulfuric acid, but the neutralization end point is pH = 7-9, at this time, sulfuric acid has reacted with sodium hydroxide, and the expected goal cannot be achieved.

[0006] Therefore, there is an urgent need for a preparation method of β-naphthalene sulfonic acid sodium formaldehyde condensate which can avoid introducing calcium and magnesium ions into the product to improve the product quality, and can also efficiently produce the β-naphthalene sulfonic acid sodium formaldehyde condensate. SUMMARY

[0007] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a β-naphthalene sulfonic acid sodium formaldehyde condensate and a preparation method thereof, so as to solve the technical problems that calcium and magnesium ions are introduced in the production of β-naphthalene sulfonic acid sodium formaldehyde condensate in the prior art, the preparation method is complex, the product quality is not high, and the yield is low.

[0008] To achieve the above-mentioned purposes and other related purposes, the present application provides a preparation method of β-naphthalene sulfonic acid sodium formaldehyde condensate, which uses naphthalene and sulfuric acid as raw materials to prepare a naphthalene sulfonic acid mixture, extracts β-naphthalene sulfonic acid from the naphthalene sulfonic acid mixture by melt crystallization, and sequentially performs condensation reaction, neutralization reaction and purification steps on the β-naphthalene sulfonic acid to obtain the β-naphthalene sulfonic acid sodium formaldehyde condensate.

[0009] The principle of the present application is that by using the large difference between the melting points of β-naphthalene sulfonic acid and α-naphthalene sulfonic acid, β-naphthalene sulfonic acid is extracted from the naphthalene sulfonic acid mixture by melt crystallization, which can ensure the purity of β-naphthalene sulfonic acid, and the separated α-naphthalene sulfonic acid can be further converted into β-naphthalene sulfonic acid, which improves the conversion rate of naphthalene and the yield of β-naphthalene sulfonic acid, and thus there is no need to remove α-naphthalene sulfonic acid by hydrolysis reaction and recover the generated naphthalene. The key is that when β-naphthalene sulfonic acid is prepared, no additional sulfuric acid is generated, so there is no need to use lime for neutralization reaction, that is, calcium and magnesium ions are not introduced, and the prepared β-naphthalene sulfonic acid can be directly used for condensation reaction. However, the condensation reaction needs to use a catalyst, sulfuric acid, and in the subsequent neutralization reaction of the condensation product, the sulfuric acid is converted into a sulfate salt by alkali, and finally removed by the purification step, which ensures the purity of the subsequent preparation of β-naphthalene sulfonic acid sodium formaldehyde condensate, and improves the yield and quality of the product.

[0010] Optionally, the melt crystallization comprises direct cooling, primary cooling, secondary cooling and temperature rising sweating in sequence.

[0011] Optionally, the naphthalene sulfonic acid mixture is directly cooled to 95-105℃.

[0012] Optionally, the primary cooling is performed at a cooling rate of 0.5℃ / 3-5min.

[0013] Optionally, the secondary cooling is performed at a cooling rate of 0.1℃ / 1-2min.

[0014] Optionally, the temperature rising sweating is performed at a temperature rising rate of 0.1℃ / 3-5min.

[0015] In the present application, the extraction of β-naphthalene sulfonic acid from the naphthalene sulfonic acid mixture comprises four processes in sequence, i.e. direct cooling, primary cooling, secondary cooling and temperature rising sweating, wherein the direct cooling is to cool the naphthalene sulfonic acid mixture at high temperature to a state ready for crystallization, the primary cooling is to slowly cool until crystals are generated, i.e. β-naphthalene sulfonic acid with a higher melting point in the naphthalene sulfonic acid mixture begins to crystallize, the secondary cooling is to further slowly cool until the crystallization of β-naphthalene sulfonic acid is completed, then the crystallization mother liquor containing a large amount of α-naphthalene sulfonic acid is discharged, and the residual α-naphthalene sulfonic acid in the β-naphthalene sulfonic acid crystals is discharged by sweating, thereby removing the α-naphthalene sulfonic acid in the naphthalene sulfonic acid mixture and obtaining β-naphthalene sulfonic acid.

[0016] The preparation method of the present application comprises the following steps:

[0017] S1, preparation of naphthalene sulfonic acid mixture: adding sulfuric acid into naphthalene to obtain a mixture, heating and keeping the mixture for one time to perform sulfonation reaction, obtaining sulfonation product, then performing azeotropic distillation and vacuum distillation on the sulfonation product in sequence, and heating and keeping the sulfonation product for two times to perform transposition reaction, thereby preparing naphthalene sulfonic acid mixture;

[0018] S2, extraction of β-naphthalene sulfonic acid: performing melt crystallization on the naphthalene sulfonic acid mixture, i.e. performing direct cooling, primary cooling and secondary cooling in sequence, then removing the crystallization mother liquor to obtain β-naphthalene sulfonic acid crystals, then performing temperature rising sweating on the β-naphthalene sulfonic acid crystals, and removing the sweating liquid to obtain β-naphthalene sulfonic acid;

[0019] S3, preparation of β-naphthalene sulfonic acid sodium formaldehyde condensate: adding formaldehyde, catalyst and solvent into the obtained β-naphthalene sulfonic acid to perform condensation reaction, adding alkali after the condensation reaction to perform neutralization reaction, then performing concentration, crystallization and filtration in sequence to remove salt in the reaction liquid, then continuing to concentrate the filtrate obtained by filtration, and finally drying to obtain the product β-naphthalene sulfonic acid sodium formaldehyde condensate.

[0020] In the present application, the base used in the neutralization reaction includes but is not limited to sodium hydroxide, and the purification steps after the condensation reaction and the neutralization reaction of the β-naphthalenesulfonic acid in turn include concentration, crystallization, filtration, and subsequent re-concentration and drying treatment, aiming to remove the by-product salt generated in the neutralization reaction and the solvent in the reaction system, so as to further improve the purity of the product.

[0021] Optionally, in step S1, the molar ratio of sulfuric acid to naphthalene is 1:1.05-1.2.

[0022] In the present application, the raw material sulfuric acid used is concentrated sulfuric acid or fuming sulfuric acid, and the sulfuric acid is added in the form of dripping, and the dripping rate is 54-108 mL / h. By adding sulfuric acid in the form of dripping and controlling the dripping rate, the sublimation of naphthalene caused by too rapid heating of the solution can be avoided.

[0023] Optionally, in step S1, the temperature is heated to 110-120°C at one time, and the temperature is kept for 1.5-2h after the one-time heating.

[0024] Optionally, in step S1, the temperature is heated to 150-165°C at the second time, and the temperature is kept for 2-2.5h after the second-time heating.

[0025] Optionally, in step S1, the azeotropic distillation uses at least one of n-heptane, petroleum ether, dichloromethane, and dichloroethane as the azeotropic agent.

[0026] In the present application, the amount of the azeotropic agent used is 160-200g.

[0027] Optionally, in step S1, the reflux time of the azeotropic distillation is 5-6h.

[0028] Optionally, in step S1, the temperature of the reduced pressure distillation is 70-100°C.

[0029] Optionally, in step S1, the pressure of the reduced pressure distillation is 0.085-0.095 MPa.

[0030] In the present application, the purpose of the azeotropic distillation is to remove the water generated in the sulfonation reaction, and the purpose of the reduced pressure distillation is to remove the unreacted refined naphthalene.

[0031] Optionally, in step S3, the molar ratio of the β-naphthalenesulfonic acid to formaldehyde is 1:0.5-1, preferably 1:0.6-0.8.

[0032] Optionally, in step S3, the catalyst includes sulfuric acid.

[0033] Optionally, in step S3, the solvent includes water.

[0034] Optionally, in step S3, the formaldehyde is added in the form of dripping.

[0035] In the present application, the formaldehyde is added into the β-naphthalenesulfonic acid by dropwise adding, so that the formaldehyde is prevented from volatilizing due to high temperature.

[0036] Optionally, in step S3, the mass ratio of the sulfuric acid to the β-naphthalenesulfonic acid is 1:4-20, preferably 1:5-10.

[0037] Optionally, in step S3, the temperature of the condensation reaction is 100-150°C, preferably 110-130°C.

[0038] Optionally, in step S3, the end point of the neutralization reaction is pH=9-10.

[0039] Optionally, in step S3, the temperature during the crystallization is 80-90°C, preferably 85-90°C.

[0040] The present application also provides a β-naphthalenesulfonic acid formaldehyde condensate prepared according to the preparation method as described above.

[0041] The present application has the following advantages:

[0042] In the present application, the β-naphthalenesulfonic acid is extracted from the naphthalenesulfonic acid mixture by using the large difference between the melting points of the β-naphthalenesulfonic acid and the α-naphthalenesulfonic acid, and then by using the melt crystallization method, and the separated α-naphthalenesulfonic acid can be further converted into the β-naphthalenesulfonic acid, so that the purity and yield of the β-naphthalenesulfonic acid can be ensured, and the α-naphthalenesulfonic acid is removed by the hydrolysis reaction and the produced naphthalene is recovered, i.e. the impurities such as calcium and magnesium ions are not introduced, and then the β-naphthalenesulfonic acid is subjected to the condensation reaction, the neutralization reaction and the purification, so that the β-naphthalenesulfonic acid formaldehyde condensate is prepared. The operation steps of the present application are simpler than those of the traditional method, the prepared β-naphthalenesulfonic acid formaldehyde condensate has high purity and high yield, and the product quality and economy are improved. DETAILED DESCRIPTION

[0043] The present application will be described in detail below with reference to specific embodiments. Other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure herein. The present application can also be implemented or applied in other different embodiments, and various modifications or changes can be made to the details in the present specification based on different viewpoints and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, but not for limiting the protection scope of the present application.

[0044] The application provides a preparation method of sodium beta-naphthalene sulfonate formaldehyde condensate, which comprises the following steps: preparing a naphthalene sulfonic acid mixture by taking naphthalene and sulfuric acid as raw materials, extracting beta-naphthalene sulfonic acid from the naphthalene sulfonic acid mixture by melt crystallization, and sequentially performing condensation reaction, neutralization reaction and purification steps on the beta-naphthalene sulfonic acid to obtain the sodium beta-naphthalene sulfonate formaldehyde condensate.

[0045] In the melt crystallization, the naphthalene sulfonic acid mixture is first directly cooled to 95-105 DEG C, then first-stage cooling is performed at a cooling rate of 0.5 DEG C / 3-5 min, second-stage cooling is performed at a cooling rate of 0.1 DEG C / 1-2 min, and finally temperature rising and sweating are performed at a temperature rising rate of 0.1 DEG C / 3-5 min.

[0046] In an embodiment of the application, the preparation method of the sodium beta-naphthalene sulfonate formaldehyde condensate comprises the following steps:

[0047] In the step S1, the naphthalene sulfonic acid mixture is prepared by adding sulfuric acid into naphthalene according to a molar ratio of 1:1.05-1.2, heating the mixture to 110-120 DEG C for the first time and keeping the temperature for 1.5-2 h to perform sulfonation reaction, performing azeotropic distillation on the sulfonation product by using an azeotropic agent, refluxing for 5-6 h, performing vacuum distillation on the sulfonation product under the conditions of 70-100 DEG C and 0.085-0.095 MPa, heating the sulfonation product to 150-165 DEG C for the second time and keeping the temperature for 2-2.5 h to perform transposition reaction, and preparing the naphthalene sulfonic acid mixture.

[0048] In the step S2, the beta-naphthalene sulfonic acid is extracted by melt crystallization on the prepared naphthalene sulfonic acid mixture, i.e. directly cooling the naphthalene sulfonic acid mixture to 95-105 DEG C, then performing first-stage cooling at a cooling rate of 0.5 DEG C / 3-5 min until crystals are generated, performing second-stage cooling at a cooling rate of 0.1 DEG C / 1-2 min until crystallization is completed, removing the crystallization mother liquor, and then performing temperature rising and sweating at a rate of 0.1 DEG C / 3-5 min, removing the sweating liquid after the temperature rising and sweating is completed, and obtaining the beta-naphthalene sulfonic acid.

[0049] In the step S3, the sodium beta-naphthalene sulfonate formaldehyde condensate is prepared by adding a catalyst sulfuric acid and a solvent water into the obtained beta-naphthalene sulfonic acid according to a mass ratio of 1:4-20, adding formaldehyde into the beta-naphthalene sulfonic acid according to a molar ratio of 1:0.5-1, performing condensation reaction at 100-150 DEG C, adding a base to perform neutralization reaction after the condensation reaction is completed, taking pH=9-10 as the end point of the neutralization reaction, sequentially performing concentration, crystallization and filtration to remove the salt in the reaction liquid, wherein the crystallization temperature is 80-90 DEG C, then continuously concentrating the filtrate obtained by the filtration, and finally performing drying treatment to obtain the product sodium beta-naphthalene sulfonate formaldehyde condensate.

[0050] In step S1, the sulfuric acid is added at a dropwise addition rate of 54-108 mL / h;

[0051] In step S1, the azeotrope includes at least one of n-heptane, petroleum ether, dichloromethane and dichloroethane, and the amount of the azeotrope is 160-200 g;

[0052] In step S3, the base added after the completion of the condensation reaction is sodium hydroxide, and the sodium salt removed in the purification step is sodium sulfate.

[0053] The present application also provides a β-naphthalene sulfonic acid sodium formaldehyde condensate prepared according to the preparation method as described above.

[0054] The present application will be described in detail below through specific examples. It should also be understood that the following examples are only used to specifically describe the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application all belong to the protection scope of the present application. The specific process parameters and the like in the following examples are only one example in the appropriate range, i.e., those skilled in the art can make appropriate selection within the range through the description herein, and are not limited to the specific values in the following examples.

[0055] In the present application, the reaction equation of the chemical reaction involved is as follows:

[0056] Sulfonation reaction:

[0057] Transposition reaction:

[0058] Condensation reaction:

[0059] Neutralization reaction:

[0060] In the present application, in the preparation process of the naphthalene sulfonic acid mixture, concentrated sulfuric acid and refined naphthalene are used as raw materials naphthalene, and the refined naphthalene needs to be heated before mixing with the concentrated sulfuric acid, so that it is dissolved into a liquid, wherein the target temperature of the heating is 80-90℃; in the preparation process of the β-naphthalene sulfonic acid sodium formaldehyde condensate, after adding the catalyst concentrated sulfuric acid and the solvent water to the β-naphthalene sulfonic acid, and before adding the formaldehyde, the solution needs to be heated.

[0061] Example 1

[0062] The present embodiment provides a preparation method of a β-naphthalene sulfonic acid sodium formaldehyde condensate, including the following steps:

[0063] S1, Preparation of naphthalene sulfonic acid mixture: 142.2g of purified naphthalene was heated to 85℃ according to the molar ratio of concentrated sulfuric acid to purified naphthalene of 1:1.1, so that the purified naphthalene was dissolved, and then 54mL (i.e. 100g) of concentrated sulfuric acid with a concentration of 98wt% was added dropwise to the purified naphthalene at a drop rate of 80mL / h, to obtain a mixture, the mixture was heated to 115℃ once and kept for 1.8h to carry out sulfonation reaction, to obtain a sulfonated product, then 180g of n-heptane was added to the sulfonated product to carry out azeotropic distillation for 5.5h, and then the sulfonated product was subjected to vacuum distillation under the condition of 0.090MPa and 85℃, and then the sulfonated product was heated to 158℃ twice and kept for 2.2h to carry out transposition reaction, to obtain a naphthalene sulfonic acid mixture;

[0064] S2, Extraction of β-naphthalene sulfonic acid: the prepared naphthalene sulfonic acid mixture was subjected to melt crystallization, i.e. the naphthalene sulfonic acid mixture was directly cooled to 100℃, and then first-stage cooling was carried out at a cooling rate of 0.5℃ / 4min, when the temperature was cooled to 88.3℃, it was observed that crystals were generated, and then second-stage cooling was carried out at a cooling rate of 0.1℃ / 1.5min, when the temperature was cooled to 82.4℃, the crystallization was completed, the crystallization mother liquor was poured out, to obtain β-naphthalene sulfonic acid crystals, and then sweating was carried out at a rate of 0.1℃ / 4min, when the temperature was increased to 88.5℃, the sweating was completed, the sweating liquor was poured out, to obtain β-naphthalene sulfonic acid;

[0065] It was detected that the mass of the β-naphthalene sulfonic acid was 145.5g, and the purity thereof was 99.1%.

[0066] S3, Preparation of β-naphthalene sulfonic acid sodium formaldehyde condensate: first, 200g of water and 15g of concentrated sulfuric acid were added to the obtained β-naphthalene sulfonic acid according to the mass ratio of sulfuric acid to β-naphthalene sulfonic acid of 1:9.7, the solution was heated to 110℃, then 46.5g of formaldehyde solution with a volume fraction of 37% was added dropwise to the β-naphthalene sulfonic acid according to the molar ratio of β-naphthalene sulfonic acid to formaldehyde of 1:0.76, the condensation reaction was carried out at 120℃ for 4h, after the condensation reaction was completed, sodium hydroxide was added to carry out neutralization reaction until pH=9, then concentration was carried out, the temperature was cooled to 85℃ for crystallization for 1h, the hot filtration was carried out, the filter cake was washed with a small amount of water and dried, to obtain sodium sulfate, meanwhile, the filter liquor was concentrated to remove a large amount of water, and then drying treatment was carried out in an oven, after crushing, a light yellow powder was obtained, which was the product β-naphthalene sulfonic acid sodium formaldehyde condensate.

[0067] It was detected that the mass of the product β-naphthalene sulfonic acid sodium formaldehyde condensate was 151.2g, and the purity thereof was 99.2%, among which, the content of sodium sulfate was 0.2%, the water content was 0.4%, the content of calcium and magnesium ions was 2PPM, in addition, the mass of the byproduct sodium sulfate was 18.7g.

[0068] Example 2

[0069] The embodiment provides a preparation method of sodium beta-naphthalene sulfonate formaldehyde condensate, and comprises the following steps:

[0070] S1, preparation of a naphthalene sulfonic acid mixture: 135.8g of refined naphthalene is heated to 90 DEG C according to a molar ratio of concentrated sulfuric acid to refined naphthalene of 1:1.05, so that the refined naphthalene is dissolved, 54mL (i.e. 100g) of concentrated sulfuric acid with a concentration of 98wt% is added dropwise into the refined naphthalene at a dropping rate of 54mL / h, a mixture is obtained, the mixture is heated to 120 DEG C once and kept for 1.5h to perform a sulfonation reaction, a sulfonated product is obtained, then 160g of petroleum ether is added into the sulfonated product to perform azeotropic distillation for 5h, then the sulfonated product is placed under the condition of 0.085MPa and 100 DEG C to perform vacuum distillation, the sulfonated product is heated to 165 DEG C again and kept for 2h to perform a transposition reaction, and the naphthalene sulfonic acid mixture is prepared;

[0071] S2, extraction of beta-naphthalene sulfonic acid: the prepared naphthalene sulfonic acid mixture is subjected to melt crystallization, that is, the naphthalene sulfonic acid mixture is directly cooled to 105 DEG C, then first-stage cooling is performed at a cooling rate of 0.5 DEG C / 3min, when the temperature is cooled to 88.7 DEG C, it is observed that crystals are generated, then second-stage cooling is performed at a cooling rate of 0.1 DEG C / 1min, when the temperature is cooled to 82.9 DEG C, the crystallization is completed, the crystallization mother liquor is poured out, and the beta-naphthalene sulfonic acid crystals are obtained, then the temperature is increased at a rate of 0.1 DEG C / 3min to perform sweating, when the temperature is increased to 88.6 DEG C, the sweating is completed, the sweating liquor is poured out, and the beta-naphthalene sulfonic acid is obtained;

[0072] It is detected that the mass of the beta-naphthalene sulfonic acid is 143.6g, and the purity is 98.9%.

[0073] S3, preparation of sodium beta-naphthalene sulfonate formaldehyde condensate: first, 200g of water and 35.9g of concentrated sulfuric acid are added into the obtained beta-naphthalene sulfonic acid according to a mass ratio of sulfuric acid to beta-naphthalene sulfonic acid of 1:4, the solution is heated to 110 DEG C, then 60.4g of formaldehyde solution with a volume fraction of 37% is added dropwise into the beta-naphthalene sulfonic acid according to a molar ratio of beta-naphthalene sulfonic acid to formaldehyde of 1:1, the condensation reaction is performed at 150 DEG C for 4h, after the condensation reaction is completed, sodium hydroxide is added to perform a neutralization reaction until the pH value is 9.2, then the solution is concentrated, the temperature is cooled to 80 DEG C to crystallize for 1h, the hot filtration is performed, the filter cake is washed with a small amount of water and dried, and sodium sulfate is obtained, meanwhile, the filter liquor is concentrated to remove a large amount of water, and then is placed in a drying oven for drying treatment, and after being crushed, a yellowish powder is obtained, which is the product sodium beta-naphthalene sulfonate formaldehyde condensate.

[0074] It is detected that the mass of the product sodium beta-naphthalene sulfonate formaldehyde condensate is 151.9g, the purity is 98.3%, the content of sodium sulfate is 0.8%, the water content is 0.4%, the content of calcium and magnesium ions is 5PPM, in addition, the mass of the byproduct sodium sulfate is 49.4g.

[0075] Example 3

[0076] The present embodiment provides a preparation method of sodium β-naphthalenesulfonate formaldehyde condensate, comprising the following steps:

[0077] S1, preparation of naphthalenesulfonic acid mixture: 155.2 g of refined naphthalene was heated to 80℃ according to the molar ratio of concentrated sulfuric acid to refined naphthalene of 1:1.2, so that the refined naphthalene was dissolved, then 54 mL (i.e. 100 g) of concentrated sulfuric acid with a concentration of 98 wt% was added dropwise to the refined naphthalene at a drop rate of 108 mL / h, to obtain a mixture, the mixture was heated to 110℃ once and kept for 2 h for sulfonation reaction, to obtain a sulfonation product, then 200 g of dichloromethane was added to the sulfonation product for azeotropic distillation for 6 h, and then the sulfonation product was subjected to reduced pressure distillation under the condition of 0.095 MPa and 70℃, and the sulfonation product was heated to 150℃ again and kept for 2.5 h for transposition reaction, to prepare a naphthalenesulfonic acid mixture;

[0078] S2, extraction of β-naphthalenesulfonic acid: the prepared naphthalenesulfonic acid mixture was subjected to melt crystallization, i.e. the naphthalenesulfonic acid mixture was directly cooled to 95℃, then first-stage cooling was performed at a cooling rate of 0.5℃ / 5 min, when the temperature was cooled to 88.4℃, it was observed that crystals were generated, then second-stage cooling was performed at a cooling rate of 0.1℃ / 2 min, when the temperature was cooled to 82.3℃, the crystallization was completed, the crystallization mother liquor was poured out, to obtain β-naphthalenesulfonic acid crystals, and then sweating was performed at a rate of 0.1℃ / 5 min, when the temperature was raised to 88.5℃, the sweating was completed, the sweating liquor was poured out, to obtain β-naphthalenesulfonic acid;

[0079] It was detected that the mass of the β-naphthalenesulfonic acid was 143.1 g, and the purity thereof was 99.05%.

[0080] S3, preparation of sodium β-naphthalenesulfonate formaldehyde condensate: first, 200 g of water and 7.2 g of concentrated sulfuric acid were added to the obtained β-naphthalenesulfonic acid according to the mass ratio of sulfuric acid to β-naphthalenesulfonic acid of 1:20, the solution was heated to 100℃, then 30.1 g of formaldehyde solution with a volume fraction of 37% was added dropwise to the β-naphthalenesulfonic acid according to the molar ratio of β-naphthalenesulfonic acid to formaldehyde of 1:0.5, the condensation reaction was performed at 100℃ for 4 h, after the condensation reaction was completed, sodium hydroxide was added for neutralization reaction until pH=10, then concentration was performed, the temperature was lowered to 90℃ for crystallization for 1 h, the hot filtration was performed, the filter cake was washed with a small amount of water and dried, to obtain sodium sulfate, meanwhile, the filter liquor was concentrated to remove a large amount of water, and then dried in an oven, to obtain a light yellow powder after crushing, which was the product, i.e. sodium β-naphthalenesulfonate formaldehyde condensate.

[0081] The product, sodium β-naphthalenesulfonate formaldehyde condensate, was tested and found to contain 146.7g of sodium sulfate with a purity of 98.8%. The sodium sulfate content was 0.1%, the moisture content was 0.5%, and the calcium and magnesium ion content was 4 PPM. In addition, the byproduct sodium sulfate contained 10.2g of sodium sulfate.

[0082] Example 4

[0083] This embodiment provides a method for preparing β-naphthalenesulfonate sodium formaldehyde condensate, which is carried out according to the preparation method of Example 1, except that:

[0084] Preparation of S3, sodium β-naphthalenesulfonate formaldehyde condensate: First, add 200g of water and 29.1g of concentrated sulfuric acid to the obtained β-naphthalenesulfonic acid at a mass ratio of sulfuric acid to β-naphthalenesulfonic acid of 1:5. Heat the solution to 110℃. Then, add 36.8g of formaldehyde solution with a volume fraction of 37% to the β-naphthalenesulfonic acid at a molar ratio of 1:0.6. Keep the solution at 120℃ for 4 hours for condensation reaction. After the condensation reaction is completed, add sodium hydroxide to neutralize the solution to pH=9.5. Then concentrate the solution and cool it to 87℃ for 1 hour for crystallization. Filter the solution while hot, wash the filter cake with a small amount of water and dry it to obtain sodium sulfate. At the same time, continue to concentrate the filtrate to remove a large amount of water. Then place the solution in an oven for drying. After pulverizing, a light yellow powder is obtained, which is the product sodium β-naphthalenesulfonate formaldehyde condensate.

[0085] The remaining steps are the same as in Example 1.

[0086] The product, sodium β-naphthalenesulfonate formaldehyde condensate, was found to contain 149.8g of sodium sulfate with a purity of 99.0%. The sodium sulfate content was 0.3%, the moisture content was 0.5%, and the calcium and magnesium ion content was 4 PPM. In addition, the byproduct sodium sulfate contained 34.3g of sodium sulfate.

[0087] Example 5

[0088] This embodiment provides a method for preparing β-naphthalenesulfonate sodium formaldehyde condensate, which is carried out according to the preparation method of Example 1, except that:

[0089] Preparation of S3, sodium β-naphthalenesulfonate formaldehyde condensate: First, add 200g of water and 14.55g of concentrated sulfuric acid to the obtained β-naphthalenesulfonic acid at a mass ratio of sulfuric acid to β-naphthalenesulfonic acid of 1:10. Heat the solution to 110℃. Then, add 49.0g of formaldehyde solution with a volume fraction of 37% to the β-naphthalenesulfonic acid at a molar ratio of 1:0.8. Keep the solution at 130℃ for 4 hours for condensation reaction. After the condensation reaction is completed, add sodium hydroxide to neutralize the solution to pH=9.5. Then concentrate the solution and cool it to 88℃ for crystallization for 1 hour. Filter the solution while hot, wash the filter cake with a small amount of water and dry it to obtain sodium sulfate. At the same time, continue to concentrate the filtrate to remove a large amount of water. Then place the solution in an oven for drying. After pulverizing, a light yellow powder is obtained, which is the product sodium β-naphthalenesulfonate formaldehyde condensate.

[0090] The remaining steps are the same as in Example 1.

[0091] The product, sodium β-naphthalenesulfonate formaldehyde condensate, was tested and found to contain 151.7g of sodium sulfate with a purity of 99.1%. The sodium sulfate content was 0.2%, the moisture content was 0.3%, and the calcium and magnesium ion content was 3 PPM. In addition, the byproduct sodium sulfate weighed 18.5g.

[0092] Comparative Example 1

[0093] The difference between this comparative example and Example 1 is that α-naphthalenesulfonic acid in the naphthalenesulfonic acid mixture is removed by hydrolysis to obtain β-naphthalenesulfonic acid (containing sulfuric acid impurities). After the β-naphthalenesulfonic acid undergoes a condensation reaction with formaldehyde, excess sulfuric acid is removed using lime. The specific steps are as follows:

[0094] Extraction of S2 and β-naphthalenesulfonic acid: The obtained naphthalenesulfonic acid mixture is placed in an acidic water system for hydrolysis. After the hydrolysis reaction is completed, steam is introduced into the obtained hydrolysis reaction solution to remove the unreacted refined naphthalene and the naphthalene produced by the hydrolysis reaction, so as to obtain 2-naphthalenesulfonic acid.

[0095] The mass of β-naphthalenesulfonic acid was measured to be 164.7g, and its purity was 92.5%.

[0096] In step S3, after the condensation reaction is completed and before the neutralization reaction, an appropriate amount of lime is added to the reaction system to remove excess sulfuric acid in the form of calcium sulfate.

[0097] The remaining preparation conditions and steps were the same as in Example 1. The product, sodium β-naphthalenesulfonate formaldehyde condensate, was tested and found to have a mass of 147.8 g and a purity of 91.3%. The sodium sulfate content was 1.8%, the moisture content was 0.5%, and the calcium and magnesium ion content was 137 PPM. In addition, the mass of the byproduct sodium sulfate was 10.1 g.

[0098] As shown in Examples 1-5, the purity of β-naphthalenesulfonic acid obtained in Examples 1-3 all reached 98.9% or higher. In Examples 1-5, the purity of the sodium naphthalenesulfonate formaldehyde condensate obtained from β-naphthalenesulfonic acid all reached 98.3% or higher, and the purity of the sodium naphthalenesulfonate formaldehyde condensate obtained in Examples 1, 4-5 reached 99.0% or higher. Simultaneously, the sodium sulfate content in the product sodium naphthalenesulfonate formaldehyde condensate was less than 1%, the moisture content was less than or equal to 5%, and the calcium and magnesium ion content was less than or equal to 5 PPM. These results indicate that the β-naphthalenesulfonic acid prepared by the method of the present invention has high purity and high yield, and the sodium naphthalenesulfonate formaldehyde condensate obtained from β-naphthalenesulfonic acid has high purity and extremely low calcium and magnesium ion content, resulting in excellent product quality.

[0099] As shown in Comparative Example 1 and Example 1, the purity of β-naphthalenesulfonic acid obtained in Comparative Example 1 was 92.5%, and the purity of the sodium β-naphthalenesulfonate formaldehyde condensate obtained from β-naphthalenesulfonic acid was 91.3%, both significantly lower than that in Example 1. Furthermore, the content of sodium sulfate, a byproduct, in Comparative Example 1 was 1.8%, higher than that in Example 1, and its calcium and magnesium ion content reached 137 PPM, far exceeding that in Example 1. These results indicate that the present invention, by extracting β-naphthalenesulfonic acid from a mixture of naphthalenesulfonic acids through melt crystallization, can avoid introducing a large amount of impurities such as calcium and magnesium ions into the product, thus improving the product quality of the sodium β-naphthalenesulfonate formaldehyde condensate.

[0100] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a sodium β-naphthalenesulfonate formaldehyde condensate, characterized in that, Includes the following steps: S1. Preparation of naphthalene sulfonic acid mixture: Sulfuric acid is added to naphthalene to obtain a mixture. The mixture is heated once and kept at a certain temperature to carry out a sulfonation reaction to obtain a sulfonated product. Then, the sulfonated product is subjected to azeotropic distillation and vacuum distillation in sequence. The sulfonated product is then heated a second time and kept at a certain temperature to carry out a transposition reaction to obtain a naphthalene sulfonic acid mixture. S2. Extraction of β-naphthalenesulfonic acid: The naphthalenesulfonic acid mixture is subjected to melt crystallization, that is, the naphthalenesulfonic acid mixture is directly cooled to 95~105℃, and then cooled once at a cooling rate of 0.5℃ / 3~5min until crystals are formed. Then, it is cooled a second time at a cooling rate of 0.1℃ / 1~2min until crystallization is complete. Then, the mother liquor of crystallization is removed to obtain β-naphthalenesulfonic acid crystals. Then, the β-naphthalenesulfonic acid crystals are heated at a heating rate of 0.1℃ / 3~5min to induce sweating. The sweating liquid is then removed to obtain β-naphthalenesulfonic acid. Preparation of S3, sodium β-naphthalenesulfonate formaldehyde condensate: formaldehyde, catalyst and solvent are added to the obtained β-naphthalenesulfonic acid to carry out a condensation reaction. After the condensation reaction is completed, alkali is added to carry out a neutralization reaction. Then, the solution is concentrated, crystallized and filtered to remove the salt in the reaction solution. The filtrate obtained by filtration is then concentrated and finally dried to obtain the product sodium β-naphthalenesulfonate formaldehyde condensate.

2. The preparation method according to claim 1, characterized in that: In step S1, the molar ratio of sulfuric acid to naphthalene is 1:1.05~1.

2.

3. The preparation method according to claim 1, characterized in that: In step S1, the temperature is heated to 110~120℃ once, and the holding time after the first heating is 1.5~2h.

4. The preparation method according to claim 1, characterized in that: In step S1, the temperature is heated a second time to 150~165℃, and the holding time after the second heating is 2~2.5h.

5. The preparation method according to claim 1, characterized in that: In step S1, the azeotropic agent used in the azeotropic distillation includes at least one of n-heptane, petroleum ether, dichloromethane, and dichloroethane.

6. The preparation method according to claim 1, characterized in that: In step S1, the reflux time for the azeotropic distillation is 5-6 hours.

7. The preparation method according to claim 1, characterized in that: In step S1, the temperature of the vacuum distillation is 70~100℃.

8. The preparation method according to claim 1, characterized in that: In step S1, the pressure of the vacuum distillation is 0.085~0.095MPa.

9. The preparation method according to claim 1, characterized in that: In step S3, the molar ratio of β-naphthalenesulfonic acid to formaldehyde is 1:0.5~1.

10. The preparation method according to claim 1, characterized in that: In step S3, the catalyst includes sulfuric acid.

11. The preparation method according to claim 1, characterized in that: In step S3, the solvent includes water.

12. The preparation method according to claim 9, characterized in that: In step S3, the formaldehyde is added dropwise.

13. The preparation method according to claim 10, characterized in that: In step S3, the mass ratio of sulfuric acid to β-naphthalenesulfonic acid is 1:4~20.

14. The preparation method according to claim 1, characterized in that: In step S3, the temperature of the condensation reaction is 100~150℃.

15. The preparation method according to claim 1, characterized in that: In step S3, the endpoint of the neutralization reaction is pH=9~10.

16. The preparation method according to claim 1, characterized in that: In step S3, the temperature during crystallization is 80~90℃.