Efficient polymerization inhibitor for styrene rectification and preparation method thereof

Abstract

The invention provides an efficient polymerization inhibitor for styrene rectification, which comprises the following components in parts by weight: 20-40 parts of a free radical trapping agent, 15-25 parts of modified alkylamine, 50-100 parts of a compound alcohol solution, 2-4 parts of sodium citrate and 1-3 parts of sodium oxalate, the free radical trapping agent is porous calcium carbonate microsphere loaded nitroxide free radicals and plant extract; the modified alkylamine is layered composite metal hydroxide LDH loaded alkylamine; the composite alcohol solution is ethylene glycol, glycerol and polyvinyl alcohol; when the catalyst is applied to styrene rectification, the polymerization inhibition capability is obviously improved by efficiently capturing free radicals.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical polymerization inhibitors, and specifically relates to a high-efficiency polymerization inhibitor for styrene distillation and a preparation method thereof. Background Art

[0002] Styrene is an important chemical raw material, widely used in many industries such as plastics, rubber, coatings, resins, etc. It is a colorless to light yellow liquid with a special aromatic smell. It can self-polymerize to form polystyrene (PS) resin, and is also easy to copolymerize with other unsaturated compounds containing double bonds. In industry, styrene is mainly produced by gas-phase catalytic dehydrogenation of ethylbenzene. The mixed liquid after ethylbenzene dehydrogenation will polymerize into polystyrene during distillation separation, which is easy to block equipment and process pipelines. Therefore, it is necessary to add inhibitors during the distillation process.

[0003] At present, the inhibitors developed at home and abroad are mainly divided into two categories: true inhibitors and retarders. True inhibitors such as nitroxide free radical compounds have high inhibition efficiency and can produce a long induction period. Almost no polymer is produced during the induction period, but they are easily consumed by free radicals and have a short service life. Retarders such as nitrophenol compounds have stable chemical properties, less failure in the inhibition process, and can reduce the polymerization rate, but cannot produce an obvious induction period, so the polymer content has been slowly increasing.

[0004] CN 101440286A has developed a polymerization inhibitor compounded of a 2,2,6,6-tetramethylpiperidine nitroxide free radical compound, a 4,6-dinitroalkylphenol compound and a dimethylthiophenylenediamine compound. The polymerization inhibitor is suitable for the production or refining process of a variety of high-boiling point olefin monomers or crosslinking agents such as styrene, divinylbenzene, and p-chloromethylstyrene, and the compound polymerization inhibitor is liquid at low temperatures; the invention patent CN102249842A discloses a high-efficiency and environmentally friendly polymerization inhibitor for styrene. The compound polymerization inhibitor is composed of a nitroxide free radical compound, a hydroxylamine compound, a nitrophenol compound and a phosphite compound. The composite system utilizes the synergistic effect between the components, overcomes the respective disadvantages of the retarder and the true inhibitor, and improves the polymerization inhibition effect.

[0005] However, studies have shown that the polymerization mechanism of styrene monomer is thermal polymerization and free radical polymerization. The factors that initiate polymerization are heat, oxygen, and metal impurities. Styrene will generate free radicals under high temperature or catalysis of metal impurities. Once free radicals are generated, polymerization will occur. The higher the free radical concentration, the faster the polymerization reaction. Therefore, a free radical scavenger is developed to improve the ability to inhibit polymerization by efficiently capturing free radicals. Summary of the invention

[0006] The purpose of the present invention is to provide a high-efficiency polymerization inhibitor for styrene distillation and a preparation method thereof. The polymerization inhibitor is obtained by compounding a free radical scavenger, a modified alkylamine and a composite alcohol solution, which significantly improves the polymerization inhibition effect of styrene.

[0007] In order to achieve the above object, the present invention provides the following technical solutions: A high-efficiency inhibitor for styrene distillation comprises the following components by weight: 20-40 parts of free radical scavengers, 15-25 parts of modified alkylamines and 50-100 parts of complex alcohol solutions.

[0008] Preferably, the free radical scavenger is porous calcium carbonate microspheres loaded with nitroxide free radicals and plant extracts; the modified alkylamine is layered composite metal hydroxide LDH loaded with alkylamine; the composite alcohol solution is ethylene glycol, glycerol and polyvinyl alcohol, and the molar ratio of the three is 1:0.3-0.6:0.5-0.8.

[0009] Preferably, the nitroxide free radical is 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical.

[0010] Preferably, the alkylamine is one or a mixture of triethylamine or diethylamine.

[0011] Preferably, it also includes 2-4 parts of sodium citrate and 1-3 parts of sodium oxalate.

[0012] The preparation method of a high-efficiency polymerization inhibitor for styrene distillation comprises the following steps: S1: Mix porous calcium carbonate microspheres and plant extract according to a solid-liquid ratio of 1g:8-15ml, add nitroxide free radicals, and stir at a temperature of 65-75°C for 1-3h to obtain a free radical scavenger; S2: Mix layered composite metal hydroxide LDH and alkylamine at a solid-liquid ratio of 1g:10-20ml, and stir at a temperature of 95-115°C for 50-80min to obtain modified alkylamine; S3: Mix ethylene glycol, glycerol and polyvinyl alcohol in a molar ratio of 1:0.3-0.6:0.5-0.8, and stir at room temperature for 25-35 minutes to obtain a composite alcohol solution; S4: Mix 20-40 parts of the free radical scavenger described in step S1, 15-25 parts of the modified alkylamine described in step S2 and 50-100 parts of the complex alcohol solution described in step S3, and stir at a temperature of 50-80° C. for 35-55 minutes; then add 2-4 parts of sodium citrate and 1-3 parts of sodium oxalate, and perform ultrasonic treatment to obtain a high-efficiency inhibitor.

[0013] Preferably, the preparation process of the porous calcium carbonate microspheres in step S1 is as follows: by weight, 80-100 parts of deionized water, 30-50 parts of phosphogypsum, 2-4 parts of potassium sorbate, 15-25 parts of cyclohexane, 3-6 parts of dodecyltrimethylammonium chloride, and 1-3 parts of citric acid are mixed evenly, and then 8-12 parts of calcium bicarbonate are added, ground for 1-2 hours, and separated and dried; and kept warm at 250-350° C. for 8-12 minutes to obtain porous calcium carbonate microspheres.

[0014] Preferably, the preparation process of the plant extract in step S1 is: by weight, 2-5 parts of mint, 2-6 parts of grapefruit and 20-40 parts of ethanol are mixed, extracted with supercritical carbon dioxide, and the temperature is controlled at 80-100 degrees Celsius and the pressure is 100-150 bar to obtain the plant extract.

[0015] Preferably, the preparation process of the layered composite metal hydroxide in step S2 is: by weight, 3-6 parts of lithium hydroxide and 5-10 parts of aluminum hydroxide are mixed and dissolved in water, 20-30 parts of 0.3-0.6 mol / L sodium salicylate aqueous solution are added thereto, and the mixture is stirred and reacted at a temperature of 150-180°C for 2-4h, and the layered composite metal hydroxide is obtained by separation and filtration, and the filter residue is dried.

[0016] Preferably, the power of the ultrasonic treatment in step S4 is 800-1000 W, the temperature is 75-85° C., and the time is 20-30 min.

[0017] Compared with the prior art, the advantages and beneficial effects of the present invention are: The present invention uses porous calcium carbonate microspheres to load nitroxide free radicals and plant extracts as free radical scavengers, making it difficult for 4-hydroxy-2,2,6,6-tetramethylpiperidinium nitroxide free radical molecules to stack in an orderly manner and form crystals in the porous calcium carbonate microsphere environment, thereby significantly reducing the viscosity of the entire system, and synergizing with free radical eliminating components in the plant extract to jointly improve the performance of the free radical scavenger; utilizing the advantages of LDH such as large specific surface area, adjustable composition and structure, etc., layered composite metal hydroxide LDH is used to load alkylamines, and acts together with the free radical scavenger; citrate and oxalate dissociated from sodium citrate and sodium oxalate can form complexes with iron ions, which can effectively reduce the catalytic activity of iron ions, prevent iron ions from catalyzing the polymerization reaction of styrene, and improve the styrene inhibition effect. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The raw materials used in the present invention are as follows: Phosphogypsum came from Wuhu Zhonglei Building Materials Co., Ltd. with item number S156; potassium sorbate came from Shanghai Yuanye Biotechnology Co., Ltd. with item number S11114; cyclohexane came from Shandong Zhengxing New Materials Co., Ltd. with item number 345; dodecyltrimethylammonium chloride came from Shanghai Xuejie Chemical Co., Ltd. with item number 134; citric acid came from Henan Zunting Biotechnology Co., Ltd. with item number 645; polyvinyl alcohol came from Sichuan Laite Juxin Pharmaceutical Excipients Co., Ltd. with item number 40.

[0020] Example 1 This embodiment provides a method for preparing a high-efficiency polymerization inhibitor for styrene distillation, comprising the following steps: S1: Take 80g deionized water, 30g phosphogypsum, 2g potassium sorbate, 15g cyclohexane, 3g dodecyltrimethylammonium chloride, and 1g citric acid and mix them evenly, then add 8g calcium bicarbonate, grind for 1h, separate and dry; keep warm at 250℃ for 8min to obtain porous calcium carbonate microspheres; 2 g of mint, 2 g of grapefruit and 20 g of ethanol were mixed and extracted with supercritical carbon dioxide at a temperature of 80° C. and a pressure of 100 bar to obtain a plant extract; Porous calcium carbonate microspheres and plant extract were mixed at a solid-liquid ratio of 1g:8ml, and nitroxide free radicals were added. The mixture was stirred at 65°C and 500r / min for 1h to obtain a free radical scavenger. S2: 3 g of lithium hydroxide and 5 g of aluminum hydroxide were mixed and dissolved in water, 20 g of 0.3 mol / L sodium salicylate aqueous solution was added thereto, the mixture was stirred at 150° C. and 500 r / min for 2 h, and the residue was dried after separation and filtration to obtain a layered composite metal hydroxide; Mix layered composite metal hydroxide LDH and triethylamine at a solid-liquid ratio of 1g:10ml, stir at 95°C and 600r / min for 50min to obtain modified alkylamine; S3: Ethylene glycol, propylene glycol and polyvinyl alcohol were mixed at a molar ratio of 1:0.3:0.5, and stirred at a rate of 600 r / min for 25 min at room temperature to obtain a composite alcohol solution; S4: Take 20g of the free radical scavenger described in step S1, 15g of the modified alkylamine described in step S2 and 50g of the complex alcohol solution described in step S3, mix them, and stir them at a temperature of 50°C and a speed of 550r / min for 35min; then add 2g of sodium citrate and 1g of sodium oxalate, and ultrasonically treat them at a power of 800W and a temperature of 75°C for 20min to obtain a high-efficiency inhibitor.

[0021] Example 2 This embodiment provides a method for preparing a high-efficiency polymerization inhibitor for styrene distillation, comprising the following steps: S1: Take 100g deionized water, 50g phosphogypsum, 4g potassium sorbate, 25g cyclohexane, 6g dodecyltrimethylammonium chloride, and 3g citric acid, mix them evenly, then add 12g calcium bicarbonate, grind for 2h, separate and dry; keep warm at 350℃ for 12min to obtain porous calcium carbonate microspheres; 5 g of mint, 6 g of grapefruit and 40 g of ethanol were mixed and extracted with supercritical carbon dioxide at a temperature of 100° C. and a pressure of 150 bar to obtain a plant extract; Porous calcium carbonate microspheres and plant extract were mixed at a solid-liquid ratio of 1g:15ml, and nitroxide free radicals were added, and the mixture was stirred at 75°C and 500r / min for 3h to obtain a free radical scavenger; S2: 6 g of lithium hydroxide and 10 g of aluminum hydroxide were mixed and dissolved in water, 30 g of 0.6 mol / L sodium salicylate aqueous solution was added thereto, and the mixture was stirred and reacted at a temperature of 180° C. for 4 h, and the residue was separated and filtered, and dried to obtain a layered composite metal hydroxide; Mix layered composite metal hydroxide LDH and triethylamine at a solid-liquid ratio of 1g:20ml, stir at 115°C and 600r / min for 80min to obtain modified alkylamine; S3: Ethylene glycol, propylene glycol and polyvinyl alcohol were mixed at a molar ratio of 1:0.6:0.8, and stirred at a rate of 400 r / min for 35 min at room temperature to obtain a composite alcohol solution; S4: Take 40g of the free radical scavenger described in step S1, 25g of the modified alkylamine described in step S2 and 100g of the complex alcohol solution described in step S3, mix them, and stir them at a temperature of 80°C and a speed of 550r / min for 55min; then add 4g of sodium citrate and 3g of sodium oxalate, and ultrasonically treat them at a power of 1000W and a temperature of 85°C for 30min to obtain a high-efficiency inhibitor.

[0022] Example 3 This embodiment provides a method for preparing a high-efficiency polymerization inhibitor for styrene distillation, comprising the following steps: S1: Take 85g deionized water, 40g phosphogypsum, 3g potassium sorbate, 22g cyclohexane, 4g dodecyltrimethylammonium chloride, and 2g citric acid and mix them evenly, then add 10g calcium bicarbonate, grind for 1.5h, separate and dry; keep warm at 320℃ for 10min to obtain porous calcium carbonate microspheres; 4 g of mint, 3 g of grapefruit and 35 g of ethanol were mixed and extracted with supercritical carbon dioxide at a temperature of 90° C. and a pressure of 120 bar to obtain a plant extract; Porous calcium carbonate microspheres and plant extract were mixed at a solid-liquid ratio of 1g:13ml, and nitroxide free radicals were added. The mixture was stirred at 70°C and a speed of 500r / min for 2.5h to obtain a free radical scavenger. S2: 5 g of lithium hydroxide and 8 g of aluminum hydroxide were mixed and dissolved in water, 25 g of a 0.45 mol / L sodium salicylate aqueous solution was added thereto, the mixture was stirred at 170° C. and a speed of 600 r / min for 3.5 h, and the residue was dried after separation and filtration to obtain a layered composite metal hydroxide; Layered composite metal hydroxide LDH and triethylamine were mixed at a solid-liquid ratio of 1g:15ml, and stirred at 100°C and a speed of 600r / min for 70min to obtain modified alkylamine; S3: Ethylene glycol, propylene glycol and polyvinyl alcohol were mixed in a molar ratio of 1:0.5:0.6, and stirred at a rate of 550 r / min for 30 min at room temperature to obtain a composite alcohol solution; S4: Take 35g of the free radical scavenger described in step S1, 20g of the modified alkylamine described in step S2 and 80g of the complex alcohol solution described in step S3, mix them, and stir them at a temperature of 75°C and a speed of 550r / min for 45min; then add 3g of sodium citrate and 2g of sodium oxalate, and ultrasonically treat them at a power of 850W and a temperature of 80°C for 25min to obtain a high-efficiency inhibitor.

[0023] Comparative Example 1 The difference between this comparative example and Example 1 is that step S1 is missing, that is, the nitroxide free radical is not subjected to modification treatment, and the other steps are the same.

[0024] Comparative Example 2 The difference between this comparative example and Example 1 is that porous calcium carbonate microspheres are missing in step S1, and the other steps are the same.

[0025] Comparative Example 3 The difference between this comparative example and Example 1 is that the plant extract is missing in step S1, and the other steps are the same.

[0026] Comparative Example 4 The difference between this comparative example and Example 1 is that the layered composite metal hydroxide LDH is missing in step S2, and the other steps are the same.

[0027] Comparative Example 5 The difference between this comparative example and Example 1 is that only ethylene glycol is used in step S3, and the other steps are the same.

[0028] Comparative Example 6 The difference between this comparative example and Example 1 is that sodium citrate and sodium oxalate are missing in step S4, and the other steps are the same.

[0029] Performance Test: The polymerization inhibitors prepared in the examples and comparative examples were respectively applied to styrene distillation. That is, 100g of styrene and 0.06g of polymerization inhibitor sample were added to a four-necked flask equipped with nitrogen purge, thermometer, reflux condenser, mechanical or magnetic stirring; after replacing the system with nitrogen, the same amount of polymerization inhibitor was used and heated at 120°C for 2h, and the polystyrene content was analyzed by sampling, wherein the amount of polymerization inhibitor sample was 0.06% of the total amount of styrene. The results are shown in Table 1.

[0030] Table 1 Performance test results

[0031] From the above performance test results, it can be seen that the polymer content of Examples 1-3 is significantly reduced, which can effectively achieve the purpose of inhibiting and slowing down styrene polymerization; in particular, the comprehensive performance of Example 3 is the most outstanding. However, since Comparative Examples 1-6 do not adopt the necessary technical solutions, their corresponding performance tests are significantly worse than those of the Examples. The above experimental results further prove the importance of the technical solutions defined in the present invention for its technical effects.

[0032] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-efficiency polymerization inhibitor for styrene distillation, characterized in that: The invention comprises the following components in parts by weight: 20-40 parts of free radical scavenger, 15-25 parts of modified alkylamine and 50-100 parts of complex alcohol solution.

2. A high-efficiency polymerization inhibitor for styrene distillation according to claim 1, characterized in that: The free radical scavenger is porous calcium carbonate microspheres loaded with nitroxide free radicals and plant extracts; the modified alkylamine is layered composite metal hydroxide LDH loaded with alkylamine; the composite alcohol solution is ethylene glycol, glycerol and polyvinyl alcohol, and the molar ratio of the three is 1:0.3-0.6:0.5-0.

8.

3. A high-efficiency polymerization inhibitor for styrene distillation according to claim 1, characterized in that: The nitroxide free radical is a 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical.

4. A high-efficiency polymerization inhibitor for styrene distillation according to claim 2, characterized in that: The alkylamine is one or a mixture of triethylamine or diethylamine.

5. A high-efficiency polymerization inhibitor for styrene distillation according to claim 1, characterized in that: Also included are 2-4 parts sodium citrate and 1-3 parts sodium oxalate.

6. A method for preparing a high-efficiency polymerization inhibitor for styrene distillation, characterized in that: The steps include: S1: Mix porous calcium carbonate microspheres and plant extract according to a solid-liquid ratio of 1g:8-15ml, add nitroxide free radicals, and stir at a temperature of 65-75°C for 1-3h to obtain a free radical scavenger; S2: Mix layered composite metal hydroxide LDH and alkylamine at a solid-liquid ratio of 1g:10-20ml, and stir at a temperature of 95-115°C for 50-80min to obtain modified alkylamine; S3: Mix ethylene glycol, glycerol and polyvinyl alcohol in a molar ratio of 1:0.3-0.6:0.5-0.8, and stir at room temperature for 25-35 minutes to obtain a composite alcohol solution; S4: Mix 20-40 parts of the free radical scavenger described in step S1, 15-25 parts of the modified alkylamine described in step S2 and 50-100 parts of the complex alcohol solution described in step S3, and stir at a temperature of 50-80° C. for 35-55 minutes; then add 2-4 parts of sodium citrate and 1-3 parts of sodium oxalate, and perform ultrasonic treatment to obtain a high-efficiency inhibitor.

7. The method for preparing a high-efficiency polymerization inhibitor for styrene distillation according to claim 1, characterized in that: The preparation process of the porous calcium carbonate microspheres in step S1 is as follows: by weight, 80-100 parts of deionized water, 30-50 parts of phosphogypsum, 2-4 parts of potassium sorbate, 15-25 parts of cyclohexane, 3-6 parts of dodecyltrimethylammonium chloride, and 1-3 parts of citric acid are mixed evenly, and then 8-12 parts of calcium bicarbonate are added, ground for 1-2 hours, and separated and dried; and the porous calcium carbonate microspheres are obtained by keeping warm at 250-350° C. for 8-12 minutes.

8. The method for preparing a high-efficiency polymerization inhibitor for styrene distillation according to claim 1, characterized in that: The preparation process of the plant extract in step S1 is as follows: by weight, 2-5 parts of mint, 2-6 parts of grapefruit and 20-40 parts of ethanol are mixed, extracted with supercritical carbon dioxide, and the temperature is controlled at 80-100 degrees Celsius and the pressure is 100-150 bar to obtain the plant extract.

9. The method for preparing a high-efficiency polymerization inhibitor for styrene distillation according to claim 1, characterized in that: The preparation process of the layered composite metal hydroxide in step S2 is as follows: by weight, 3-6 parts of lithium hydroxide and 5-10 parts of aluminum hydroxide are mixed and dissolved in water, 20-30 parts of 0.3-0.6 mol / L sodium salicylate aqueous solution are added thereto, and the mixture is stirred and reacted at a temperature of 150-180° C. for 2-4 hours, and the layered composite metal hydroxide is obtained by separation and filtration, and the filter residue is dried.

10. The method for preparing a high-efficiency polymerization inhibitor for styrene distillation according to claim 1, characterized in that: The power of the ultrasonic treatment in step S4 is 800-1000 W, the temperature is 75-85° C., and the time is 20-30 min.

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