Synthesis process of low-calcium polyepoxysuccinic acid

Abstract

The invention relates to a synthesis process of low-calcium polyepoxysuccinic acid, and belongs to the field of chemical engineering. The synthesis process comprises the following steps: adding water and caustic soda liquid into a reaction kettle, and adding maleic anhydride; maintaining the reaction temperature to be 70-80 DEG C, dropwise adding hydrogen peroxide, adding an epoxidation reaction catalyst for multiple times during dropwise adding, and maintaining the pH value to be 4.0-6.5 by using liquid caustic soda; after the hydrogen peroxide is dropwise added, the temperature is kept at 70-80 DEG C, the pH value is 4.0-6.5, and the temperature is kept for 3 hours; after heat preservation is finished, liquid caustic soda is added into the reaction kettle, the temperature is increased to 80-90 DEG C, the pH value is increased to 10.0-12.5, calcium salt is added, the temperature is increased to 90-95 DEG C, negative pressure is started for concentration, heat preservation is continued for 2 hours at normal pressure of 90-95 DEG C, and the reaction is finished; and supplementing water into the reaction kettle, and cooling to below 50 DEG C to obtain the low-calcium PESA product. According to the invention, the problem that calcium ions contained in PESA are combined with silicate to generate calcium silicate precipitate is solved, so that PESA can be better used in the water quality condition containing silicate.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry, and particularly relates to a synthesis process of low-calcium polyepoxysuccinic acid. Background Art

[0002] PESA (polyepoxysuccinic acid) is a nitrogen-free, sulfur-free, and phosphorus-free water treatment agent product that has the dual functions of scale inhibition and corrosion inhibition. It is one of the few polymer products with corrosion inhibition effects. It has good biodegradability and is suitable for high-alkali and high-metal content water systems. It is a green water treatment chemical.

[0003] Calcium salts are generally used as polymerization initiators in the polymerization process of PESA, such as calcium hydroxide, calcium chloride, organic carboxylic acid calcium, etc. The calcium ion concentration of conventional PESA products is 4500-6000ppm. If conventional PESA products are added to water containing silicates, calcium ions will quickly combine with silicates to form white calcium silicate precipitation, resulting in reduced product performance, which is manifested in a decrease in chelation value and calcium carbonate scale inhibition ability.

[0004] On the basis of the existing PESA production process, the reaction concentration of the reactants is increased and the process is optimized and adjusted, so that the calcium ion concentration in PESA can be reduced to below 3000ppm. The PESA synthesized by this method is very stable in water containing silicates and will not become turbid or precipitate when left at room temperature for one month. Summary of the invention

[0005] The purpose of the present invention is to provide a synthesis process of low-calcium polyepoxysuccinic acid to solve the problem of calcium silicate precipitation generated by the combination of calcium ions contained in PESA itself with silicates, so that PESA can be better used in water conditions containing silicates.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A synthesis process of low-calcium polyepoxysuccinic acid comprises the following steps:

[0008] 200-300 parts by weight of water and 300-500 parts by weight of 48 wt% liquid caustic soda are added into a reaction kettle, 300-500 parts by weight of maleic anhydride are added, and the temperature is controlled at 65-75°C;

[0009] Maintaining the reaction temperature at 70-80° C., dripping 400-500 parts by weight of 35 wt% hydrogen peroxide, adding 8-15 parts by weight of an epoxidation catalyst in 9 portions during the dripping, and simultaneously maintaining the pH value of the reaction solution between 4.0 and 6.5 with 48 wt% of liquid caustic soda;

[0010] After the addition of hydrogen peroxide is completed, the reaction temperature is maintained at 70-80°C, the pH value is 4.0-6.5, and the temperature is kept for 3 hours;

[0011] After the heat preservation is completed, 50 to 100 parts by weight of 48 wt% liquid alkali is added to the reactor, the temperature of the reactor is raised to 80 to 90 ° C, the pH value is raised to 10.0 to 12.5, 10 to 15 parts by weight of calcium salt is added, the temperature is raised to 90 to 95 ° C, the negative pressure equipment is turned on for concentration, the pressure in the reactor is maintained at -30 to -100 KPa, 600 to 1000 parts by weight of water are concentrated within 3 hours, and the temperature is kept at 90 to 95 ° C at normal pressure for 2 hours, and the reaction is completed;

[0012] 400-500 parts by weight of water are added into the reactor and the temperature is lowered to below 50° C. to obtain a low-calcium PESA product.

[0013] Furthermore, the epoxidation reaction catalyst is a vanadium-tungsten compound, including vanadium oxide, sodium metavanadate, tungsten oxide, and sodium tungstate.

[0014] Furthermore, the calcium salt is one of calcium hydroxide, calcium chloride, and organic calcium carboxylate.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] Compared with the conventional PESA synthesis process, the synthesis process of the present invention has a higher reactant concentration, can improve the conversion rate of the epoxidation reaction and the polymerization reaction, and improve the molecular weight of PESA; the catalyst is added in batches during the epoxidation process, which can not only ensure that there is a sufficient amount of catalyst in the initial stage of the reaction, but also prevent the relative catalyst concentration from decreasing due to the addition of raw materials during the reaction, thereby improving the epoxidation reaction conversion rate; the calcium ion content in the synthesized PESA is less than 3000ppm. DETAILED DESCRIPTION

[0017] In order to better understand the present invention, the present invention is further described below in conjunction with examples. The following examples are only intended to illustrate the present invention rather than to limit it.

[0018] Example 1

[0019] Add 220kg of pure water and 450kg of 48wt% liquid caustic soda to a 2000L reactor equipped with stirring, online pH detection equipment, temperature control equipment, and negative pressure concentration equipment. After stirring evenly, add 300kg of maleic anhydride to the reactor at a temperature below 75℃ while turning on the cooling water, strictly control the temperature in the reactor to 65-75℃, and then add 100kg of maleic anhydride.

[0020] The temperature in the reactor was controlled at 70-80°C, and 5kg of sodium tungstate was added; then 170kg of 35wt% hydrogen peroxide was added dropwise, and 1.5kg of sodium tungstate was added to the reactor (added in 5 batches) during the reaction. During the reaction, 48wt% liquid alkali was used to adjust the pH to control pH=5.0-5.8; the temperature in the reactor was controlled at 70-80°C, and 260kg of 35wt% hydrogen peroxide was added dropwise. During the reaction, 5kg of sodium tungstate was added to the reactor (added in 3 batches), and 48wt% liquid alkali was used to adjust the pH to control pH=5.0-5.8. After the addition was completed, the temperature in the reactor was controlled at 70-80°C and kept warm for 3h.

[0021] After the insulation is completed, add 60-80 kg of liquid alkali (48 wt%) to the kettle to neutralize the reaction materials to pH = 11.0-12.0, turn on the heating appropriately, and raise the temperature to 80-90 ° C. Add 12 kg of calcium chloride to the reactor, control the temperature in the reactor to 90-95 ° C, and the pressure in the reactor to -30-40 KPa. After insulation for 2 hours, observe the liquid level in the kettle. After reaching the specified liquid level, continue to keep warm at normal pressure for 2 hours.

[0022] Add 500kg of water (concentrated water can be used directly), cool down to below 50℃, and appropriately adjust the content, pH value and other indicators to obtain the finished PESA.

[0023] The molecular weight (Mw) of the sample was 920, and the calcium ion content in the sample was 2600 ppm using ICP detection.

[0024] Silicate stability test: In a 100mL beaker, add 82.16g water, 13g PESA, 1.34g sodium silicate, and 3.5g sodium hydroxide in sequence, stir and mix evenly, and place at room temperature for 1 month. The sample remains clear and transparent.

[0025] Example 2

[0026] Add 220kg of pure water and 675kg of 32% liquid caustic soda to a 2000L reactor equipped with stirring, online pH detection equipment, temperature control equipment, and negative pressure concentration equipment. After stirring evenly, add 300kg of maleic anhydride to the reactor under the condition of turning on the cooling water and controlling the temperature below 75℃, strictly control the temperature in the reactor to 65-75℃, and then add 100kg of maleic anhydride.

[0027] The temperature in the reactor was controlled at 70-80°C, and 15 kg of sodium tungstate was added; then 550 kg of 27.5 wt% hydrogen peroxide was added dropwise, and 32 wt% of liquid alkali was used to adjust the pH during the reaction, and the pH was controlled to be 5.0-5.8. After the addition was completed, the temperature in the reactor was controlled at 70-80°C and kept warm for 3 hours.

[0028] After the insulation is completed, add 90-120 kg of liquid alkali (32 wt% content) to the kettle to neutralize the reaction materials to pH = 11.0-12.0, turn on the heating appropriately, and raise the temperature to 80-90 ° C. Add 20 kg of calcium chloride to the reactor, control the temperature in the reactor to 90-95 ° C, and keep it warm at normal pressure for 4 hours.

[0029] The temperature is lowered to below 50°C, and the content, pH value and other indicators are appropriately adjusted to obtain the finished PESA.

[0030] The molecular weight (Mw) of the sample was 940, and the calcium ion content in the sample was 4800 ppm using ICP detection.

[0031] Silicate stability test: In a 100mL beaker, add 82.16g water, 13g PESA, 1.34g sodium silicate, and 3.5g sodium hydroxide in sequence, stir and mix evenly, and place at room temperature for 24 hours. The sample becomes white and turbid with white precipitate at the bottom.

[0032] Example 3

[0033] Add 220kg of pure water and 675kg of 32wt% liquid caustic soda to a 2000L reactor equipped with stirring, online pH detection equipment, temperature control equipment, and negative pressure concentration equipment. After stirring evenly, add 300kg of maleic anhydride to the reactor at a temperature below 75℃ while turning on the cooling water, strictly control the temperature in the reactor to 65-75℃, and then add 100kg of maleic anhydride.

[0034] The temperature in the reactor was controlled at 70-80°C, and 15 kg of sodium tungstate was added; then 550 kg of 27.5 wt% hydrogen peroxide was added dropwise, and 32 wt% of liquid alkali was used to adjust the pH during the reaction, and the pH was controlled to be 5.0-5.8. After the addition was completed, the temperature in the reactor was controlled at 70-80°C and kept warm for 3 hours.

[0035] After the insulation is completed, add 90-120 kg of liquid alkali (32 wt% content) to the kettle to neutralize the reaction materials to pH = 11.0-12.0, turn on the heating appropriately, and raise the temperature to 80-90 ° C. Add 15 kg of calcium chloride to the reactor, control the temperature in the reactor to 90-95 ° C, and keep it warm at normal pressure for 4 hours.

[0036] The temperature is lowered to below 50°C, and the content, pH value and other indicators are appropriately adjusted to obtain the finished PESA.

[0037] The molecular weight (Mw) of the sample was 680, and the calcium ion content in the sample was 3200 ppm using ICP detection.

[0038] Silicate stability test: 82.16 g of water, 13 g of PESA, 1.34 g of sodium silicate, and 3.5 g of sodium hydroxide were added to a 100 mL beaker in sequence, and the mixture was stirred to mix evenly. The mixture was placed at room temperature for 72 hours, and white turbidity appeared in the sample.

[0039] Example 4

[0040] Add 220kg of pure water and 450kg of 48wt% liquid caustic soda to a 2000L reactor equipped with stirring, online pH detection equipment, temperature control equipment, and negative pressure concentration equipment. After stirring evenly, add 300kg of maleic anhydride to the reactor at a temperature below 75℃ while turning on the cooling water, strictly control the temperature in the reactor to 65-75℃, and then add 100kg of maleic anhydride.

[0041] The temperature in the reactor was controlled at 70-80°C, and 15 kg of sodium tungstate was added; then 450 kg of 35% hydrogen peroxide was added dropwise, and during the reaction, 48 wt% of liquid alkali was used to adjust the pH to 5.0-5.8. After the addition was completed, the temperature in the reactor was controlled at 70-80°C and kept warm for 3 hours.

[0042] After the insulation is completed, add 60-80 kg of liquid alkali (48 wt%) to the kettle to neutralize the reaction materials to pH = 11.0-12.0, turn on the heating appropriately, and raise the temperature to 80-90 ° C. Add 15 kg of calcium chloride to the reactor, control the temperature in the reactor to 90-95 ° C, and the pressure in the reactor to -30-40 KPa. After insulation for 2 hours, observe the liquid level in the kettle. After reaching the specified liquid level, continue to keep warm for 2 hours at normal pressure.

[0043] Add 500kg of water (concentrated water can be used directly), cool down to below 50℃, and appropriately adjust the content, pH value and other indicators to obtain the finished PESA.

[0044] The molecular weight (Mw) of the sample was 830, and the calcium ion content in the sample was 3200 ppm using ICP detection.

[0045] Silicate stability test: 82.16 g of water, 13 g of PESA, 1.34 g of sodium silicate, and 3.5 g of sodium hydroxide were added to a 100 mL beaker in sequence, and the mixture was stirred to mix evenly. The mixture was placed at room temperature for 72 hours, and white turbidity appeared in the sample.

[0046] Examples 1 to 4 are analyzed and compared, as shown in Table 1 below.

[0047] Table 1 Comparison results of Examples 1 to 4

[0048]

[0049] *Note: Calcium carbonate scale inhibition test conditions (GBT 16632-2019 Determination of scale inhibition performance of water treatment agents Calcium carbonate deposition method): Ca 2+ Concentration = 600ppm, HCO3 - Concentration = 600ppm (calculated as CaCO3), pH = 8.5, reagent addition concentration = 5ppm, experimental temperature = 80℃, placement time = 10 hours.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A synthesis process for low-calcium polyepoxysuccinic acid, characterized in that: The synthesis process comprises the following steps: 200-300 parts by weight of water and 300-500 parts by weight of 48 wt% liquid caustic soda are added into a reaction kettle, 300-500 parts by weight of maleic anhydride are added, and the temperature is controlled at 65-75°C; Maintaining the reaction temperature at 70-80° C., dripping 400-500 parts by weight of 35 wt% hydrogen peroxide, adding 8-15 parts by weight of an epoxidation catalyst in 9 portions during the dripping, and simultaneously maintaining the pH value of the reaction solution between 4.0 and 6.5 with 48 wt% of liquid caustic soda; After the addition of hydrogen peroxide is completed, the reaction temperature is maintained at 70-80°C, the pH value is 4.0-6.5, and the temperature is kept for 3 hours; After the heat preservation is completed, 50 to 100 parts by weight of 48 wt% liquid alkali is added to the reactor, the temperature of the reactor is raised to 80 to 90 ° C, the pH value is raised to 10.0 to 12.5, 10 to 15 parts by weight of calcium salt is added, the temperature is raised to 90 to 95 ° C, the negative pressure equipment is turned on for concentration, the pressure in the reactor is maintained at -30 to -100 KPa, 600 to 1000 parts by weight of water are concentrated within 3 hours, and the temperature is kept at 90 to 95 ° C at normal pressure for 2 hours, and the reaction is completed; 400-500 parts by weight of water are added into the reactor and the temperature is lowered to below 50° C. to obtain a low-calcium PESA product.

2. The synthesis process of low-calcium polyepoxysuccinic acid according to claim 1, characterized in that: The epoxidation reaction catalyst is a vanadium-tungsten compound, including vanadium oxide, sodium metavanadate, tungsten oxide, and sodium tungstate.

3. The synthesis process of low-calcium polyepoxysuccinic acid according to claim 1, characterized in that, The calcium salt is one of calcium hydroxide, calcium chloride and organic calcium carboxylate.

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