A method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation

Abstract

This invention discloses a method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation, belonging to the field of antifreeze technology. This invention addresses the technical problems of existing antifreeze agents for coal transportation, such as complex composition and poor antifreeze and metal corrosion resistance. The method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation includes the following steps: mixing a compound pour point depressant, a modified corrosion inhibitor, a thickening stabilizer, and industrial water. The compound pour point depressant includes organic and inorganic pour point depressants; the organic pour point depressant is obtained by reacting unsaturated nitrile, sodium methyl methacrylate, and fumaric acid; the unsaturated nitrile is obtained by reacting intermediate B with benzaldehyde, and intermediate B is obtained by reacting triazole with ethyl chloroacetate; the modified corrosion inhibitor is obtained by reacting potassium thiocyanate, benzoyl chloride, and chitosan vanillin Schiff base. The antifreeze prepared by this invention has the advantages of moderate fluidity, good metal corrosion resistance, and good antifreeze performance.

Description

Technical Field

[0001] This invention relates to the field of antifreeze technology, specifically to a method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation. Background Technology

[0002] Coal cargo is prone to freezing during loading, unloading, storage, and transportation in winter, making it difficult to handle and impacting production as well as vehicle turnaround efficiency. Using chemical antifreeze agents with good antifreeze and thawing capabilities to solve the problem of unloading frozen coal can significantly reduce the freezing intensity of the coal and is highly effective in solving the transportation problems of coal or granular cargo in winter. Patent application CN1261522C discloses a high-efficiency anti-corrosion and antifreeze agent for coal transportation and its preparation method. This antifreeze agent includes ethylene glycol, calcium chloride, triethanolamine, and deionized water. The above-mentioned polyhydroxy alcohol mixture achieves its antifreeze effect by weakening the hydrogen bonding forces between water molecules. However, antifreeze agents composed of low molecular weight polyols have drawbacks such as low density and viscosity, high fluidity, and lack of corrosion resistance to metals. Furthermore, the above-mentioned antifreeze agent has a relatively high chlorine content, which can easily cause rust and corrosion in coal-fired equipment, transportation equipment, and spraying equipment.

[0003] The main components of chlorine-free antifreeze for coal transportation are C, H, and O, with no other harmful elements, and it poses no corrosive hazard to non-ferrous metals. Patent application CN113046026A discloses a chlorine-free, low-corrosion coal antifreeze. This antifreeze includes an antifreeze agent, a wall-mounting agent, an organic corrosion inhibitor, an organic corrosion inhibitor, an organic surfactant, and water. The components of this coal transportation antifreeze do not contain chlorine or inorganic salts. The organic corrosion inhibitor is benzotriazole, the antifreeze is diethylene glycol diglycidyl ether or diethylene glycol dimethyl ether, and the wall-mounting agent is a water-based adhesive made from animal or plant colloids. However, the composition of this antifreeze is complex, and its anti-corrosion performance and antifreeze effect are poor.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation, which solves the technical problems of complex antifreeze composition and poor antifreeze and anti-metal corrosion properties in the existing technology.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation includes the following steps:

[0008] S1, the compound pour point depressant, modified corrosion inhibitor and thickening stabilizer are mixed to obtain component A;

[0009] S2, component A and industrial water are mixed, stirred and allowed to stand to obtain a backup solution; the backup solution is stirred further to prepare a low-chlorine composite environmentally friendly coal transportation antifreeze agent.

[0010] The antifreeze agent for coal transportation prepared by this invention is obtained by mixing a compound pour point depressant, a modified corrosion inhibitor, a thickening stabilizer, and industrial water.

[0011] The compound pour point depressant is obtained by reacting unsaturated nitrile, sodium methyl methacrylate, and fumaric acid; the unsaturated nitrile is obtained by reacting intermediate B with benzaldehyde, and intermediate B is obtained by reacting triazole with ethyl chloroacetate.

[0012] The modified corrosion inhibitor is obtained by reacting potassium thiocyanate, benzoyl chloride and chitosan vanillin Schiff base.

[0013] Furthermore, the preparation method of the compound pour point depressant includes the following steps:

[0014] A1, triazole, acetone, potassium carbonate and ethyl chloroacetate were mixed to obtain the reactant; the reactant was heated to 58-65℃ and refluxed at this temperature for 10-12 hours, then filtered under reduced pressure to obtain the filtrate; the filtrate was distilled to obtain intermediate A;

[0015] Using acetone as a solvent and potassium carbonate as an acid-binding agent, triazole and ethyl chloroacetate undergo a nucleophilic substitution reaction to yield the reactant. The reactant is then processed to prepare intermediate A. The reaction formula is as follows:

[0016]

[0017] A2. Add intermediate A to ethanol, then add hydrazine hydrate, and reflux at 75-80℃ for 10-12 h to obtain a reaction solution; after post-processing, the reaction solution is used to prepare intermediate B.

[0018] Using ethanol as a solvent, the hydrazine group of hydrazine hydrate attacks the carbonyl carbon of the ester group to form a tetrahedral intermediate. Ethanol acts as a leaving group to remove the intermediate, generating an acylhydrazine structure. The reaction formula for intermediate A and hydrazine hydrate to obtain intermediate B is as follows:

[0019]

[0020] A3, intermediate B, benzaldehyde and acetic acid are mixed and heated under reflux at 105-120℃ for 20-30 min, then cooled, the solid is precipitated, filtered, and the crude product is obtained; the crude product is recrystallized from acetic acid to synthesize unsaturated nitrogen azole;

[0021] Intermediate B reacts with benzaldehyde to form a hydrazone bond, as shown in the following reaction equation:

[0022]

[0023] A4. Under an inert gas atmosphere, deionized water, unsaturated azole, initiator, thiol, sodium methacrylate sulfonate, and fumaric acid are mixed to obtain a reaction system. The reaction system is reacted at 80-90℃ for 3-6 hours. After the reaction is completed, the product is obtained. The pH of the product is adjusted to 7-8 with NaOH solution to obtain a compound pour point depressant.

[0024] Under the action of an initiator, sodium methacrylate and fumaric acid can undergo addition polymerization with thiol as a chain transfer agent; and the hydrazide structure in the unsaturated nitrile can undergo hydrogen bonding association with the carboxyl group of fumaric acid, thereby preparing a compound pour point depressant.

[0025] Further, in step A1, the ratio of triazole, acetone, potassium carbonate and ethyl chloroacetate is 7-14g:100mL:3-5g:12.2-24.5g; the distillation temperature of the filtrate is 35-40℃.

[0026] Furthermore, in step A2, the ratio of intermediate A, ethanol, and hydrazine hydrate is 15-25g:100mL:5-10g.

[0027] Furthermore, in step A3, the ratio of intermediate B, benzaldehyde, and acetic acid is 5-35g:10.6-21.2g:100mL.

[0028] Further, in step A4, the initiator is sodium persulfate, and the inorganic pour point depressant is any one of magnesium nitrate, calcium nitrate, or sodium nitrate; the ratio of deionized water, unsaturated nitrile, initiator, thiol, sodium methyl methacrylate sulfonate, fumaric acid, and inorganic pour point depressant is 50-100mL:20-30g:1.5-3.5g:1-5g:12-24g:11.6-23.2g:3-10g.

[0029] Furthermore, the preparation method of the modified corrosion inhibitor includes the following steps:

[0030] An ethyl acetate solution of potassium thiocyanate, benzoyl chloride, and chitosan vanillin Schiff base were mixed to obtain a reactant. The reactant was reacted at 50-60℃ for 2-3 hours, then filtered to remove the generated potassium chloride, and the filtrate was collected. The filtrate was cooled and recrystallized to prepare a modified corrosion inhibitor.

[0031] Potassium thiocyanate and benzoyl chloride undergo an acylthiourea reaction to obtain a product containing a thiourea structure; potassium thiocyanate can react with the imino group in the chitosan vanillin Schiff base to prepare a modified corrosion inhibitor.

[0032] Furthermore, the concentration of the ethyl acetate solution of potassium thiocyanate is 0.01-0.02 mol / L; the ratio of the ethyl acetate solution of potassium thiocyanate, benzoyl chloride and chitosan vanillin Schiff base is 10-20 mL: 2.8-5.6 g: 2-5 g.

[0033] Further, in step S1, the weight ratio of the compound pour point depressant, modified corrosion inhibitor, and thickening stabilizer is 40-60:5-10:0.05-0.1; in step S2, the dosage ratio of component A to industrial water is 45.05-70.1:40-50; in step S2, the mixing and stirring time of component A and industrial water is 1-2 hours, and the standing time is 15-20 minutes; the stirring time of the backup liquid is 1-2 hours.

[0034] The present invention has the following beneficial effects:

[0035] 1. Triazole reacts sequentially with ethyl chloroacetate, hydrazine hydrate, and benzaldehyde to synthesize unsaturated azoles. The structure of unsaturated azoles includes a five-membered heterocyclic aromatic compound and an imine structure. In the heterocyclic structure, the lone pair electrons of the nitrogen atom are delocalized, allowing them to form coordinate bonds with empty d orbitals in the metal, thus enabling the unsaturated azoles to adsorb onto the metal surface and reduce corrosion. Sodium methyl methacrylate and fumaric acid can undergo free radical addition polymerization under the action of an initiator, forming a product that can form a hydrogen bond network with moisture in coal. The imine structure of the unsaturated azoles can react with the carboxyl group in fumaric acid to form a compound pour point depressant with a long molecular chain. Through steric hindrance, this compound pour point depressant can interfere with the regular arrangement of ice crystals, enhancing its pour point depressing effect. In addition, the long-chain compound pour point depressant can increase the viscosity of the coal-water mixture and increase intermolecular frictional resistance, thus giving the antifreeze with simple doped components a certain degree of frictional resistance and viscosity. The above-mentioned compound pour point depressant also contains a small amount of inorganic pour point depressant. Through the synergistic effect between organic and inorganic pour point depressants, the freezing point can be lowered more effectively, thereby achieving a better pour point depressing effect.

[0036] 2. Chitosan modification can form chitosan vanillin Schiff bases containing C=N double bonds. Structurally, chitosan vanillin Schiff bases perfectly match the characteristics of good corrosion inhibitors. Furthermore, they are non-toxic to the environment and can be completely degraded by microorganisms or fungi, making them an environmentally friendly, green slow-release agent. After the chitosan vanillin Schiff base undergoes an acylation reaction with potassium thiocyanate, the resulting thiourea structure can form a relatively tight adsorption on the metal surface, creating a protective film. This hinders corrosive media and enhances the slow-release effect.

[0037] 3. To avoid the crystal precipitation problem associated with single-component antifreeze agents, the antifreeze prepared in this invention also incorporates a small amount of the thickening and stabilizing agent guar gum. Guar gum is rich in hydroxyl groups, and in addition to its thickening effect, it can form a hydrogen bond network with water molecules in coal, thereby disrupting the ordered structure of water molecules within the liquid and enhancing antifreeze performance. The antifreeze agent for coal transportation prepared in this invention has a simple composition, containing only industrial water, a compound pour point depressant, a modified corrosion inhibitor, and the thickening and stabilizing agent guar gum. It has the advantages of being chlorine-free and harmless, having good antifreeze effect, and strong corrosion resistance. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The guar gum used in Examples 8-10 of this invention was purchased from Guangdong Osman Biotechnology Co., Ltd., and its mesh size was 80 mesh.

[0040] Example 1

[0041] This embodiment provides a method for preparing a compound pour point depressant for a low-chlorine composite environmentally friendly coal transportation antifreeze agent, including the following steps:

[0042] A1. A 250 mL three-necked reaction flask was selected, equipped with a stirrer and a reflux condenser. 7 g of triazole, 100 mL of acetone, 3 g of potassium carbonate, and 12.2 g of ethyl chloroacetate were added to the flask and mixed thoroughly to obtain the reactants. The reactants were heated to 58 °C and refluxed at this temperature for 10 h. The mixture was then filtered under reduced pressure to obtain the filtrate. The filtrate was distilled under reduced pressure at 35 °C to remove the acetone, yielding intermediate A.

[0043] A2. Weigh 15g of intermediate A and 100mL of ethanol and add them to a 250mL three-necked reaction flask. Then add 5g of hydrazine hydrate and reflux at 75℃ for 10h at 100r / min to obtain a reaction solution. Distill the reaction solution to remove ethanol, obtaining a residue. Cool the residue to room temperature naturally, and a solid precipitates. Filter the solid, wash it with deionized water, and dry it at 75℃ to constant weight to obtain intermediate B.

[0044] A3. Weigh 15g of intermediate B, 10.6g of benzaldehyde and 100mL of acetic acid and add them to a 250mL three-necked reaction flask. Heat under reflux at 105℃ for 20min, then cool to precipitate the solid. Filter to obtain the crude product. Recrystallize the crude product from ethanol to synthesize unsaturated nitrazole.

[0045] A4. Select a 500mL laboratory reactor equipped with a thermometer, stirrer, reflux condenser, and inert gas inlet pipe. Purge the air in the reactor with nitrogen through the inert gas inlet pipe. Add 50mL of deionized water, 20g of unsaturated azole, 1.5g of sodium persulfate (initiator), 1g of thiol, 12g of sodium methyl methacrylate sulfonate, and 11.6g of fumaric acid sequentially to the reactor, mix well, and obtain the reaction system. Heat the laboratory reactor to 80℃ and react at this temperature for 3 hours. After the reaction is complete, obtain the product. Adjust the pH of the product to 7 using 0.1mol / L NaOH solution, then add 3g of magnesium nitrate (an inorganic pour point depressant) and mix well to obtain a compound pour point depressant.

[0046] Example 2

[0047] This embodiment provides a method for preparing a compound pour point depressant for a low-chlorine composite environmentally friendly coal transportation antifreeze agent, including the following steps:

[0048] A1. A 250 mL three-necked reaction flask was selected, equipped with a stirrer and a reflux condenser. 12 g of triazole, 100 mL of acetone, 4 g of potassium carbonate, and 18.5 g of ethyl chloroacetate were added to the flask and mixed thoroughly to obtain the reactants. The reactants were heated to 62 °C and refluxed at this temperature for 11 h. The mixture was then filtered under reduced pressure to obtain the filtrate. The filtrate was distilled under reduced pressure at 38 °C to remove the acetone, yielding intermediate A.

[0049] A2. Weigh 20g of intermediate A and 100mL of ethanol into a 250mL three-necked reaction flask, then add 8g of hydrazine hydrate. Reflux at 77℃ for 11h at 150r / min to obtain a reaction solution. Distill the reaction solution to remove ethanol, obtaining a residual liquid. Allow the residual liquid to cool naturally to room temperature, and a solid precipitates. Filter the solid, wash with deionized water, and dry at 80℃ to constant weight to obtain intermediate B.

[0050] A3. Weigh 25g of intermediate B, 15.6g of benzaldehyde and 100mL of acetic acid and add them to a 250mL three-necked reaction flask. Heat under reflux at 110℃ for 25min, then cool to precipitate the solid. Filter to obtain the crude product. Recrystallize the crude product from ethanol to synthesize unsaturated nitrazole.

[0051] A4. Select a 500mL laboratory reactor equipped with a thermometer, stirrer, reflux condenser, and inert gas inlet pipe. Purge the air in the reactor with nitrogen through the inert gas inlet pipe. Add 80mL of deionized water, 25g of unsaturated azole, 2.5g of sodium persulfate (initiator), 3g of thiol, 18g of sodium methyl methacrylate sulfonate, and 17.4g of fumaric acid sequentially to the reactor. Mix well to obtain the reaction system. Heat the laboratory reactor to 85℃ and react at this temperature for 5 hours. After the reaction, obtain the product. Adjust the pH of the product to 7.7 using 0.15mol / L NaOH solution, then add 5g of the inorganic pour point depressant calcium nitrate and mix well to obtain a compound pour point depressant.

[0052] Example 3

[0053] This embodiment provides a method for preparing a compound pour point depressant for a low-chlorine composite environmentally friendly coal transportation antifreeze agent, including the following steps:

[0054] A1. A 250 mL three-necked reaction flask was selected, equipped with a stirrer and a reflux condenser. 14 g of triazole, 100 mL of acetone, 5 g of potassium carbonate, and 24.5 g of ethyl chloroacetate were added to the flask and mixed thoroughly to obtain the reactants. The reactants were heated to 65 °C and refluxed at this temperature for 12 h. The mixture was then filtered under reduced pressure to obtain the filtrate. The filtrate was distilled under reduced pressure at 40 °C to remove the acetone, yielding intermediate A.

[0055] A2. Weigh 25g of intermediate A and 100mL of ethanol and add them to a 250mL three-necked reaction flask. Then add 10g of hydrazine hydrate and reflux at 200r / min and 80℃ for 12h to obtain a reaction solution. Distill the reaction solution to remove ethanol, and obtain a residue. Cool the residue to room temperature naturally, and a solid will precipitate. Filter the solid, wash it with deionized water, and dry it at 85℃ to constant weight to obtain intermediate B.

[0056] A3. Weigh 35g of intermediate B, 21.2g of benzaldehyde and 100mL of acetic acid and add them to a 250mL three-necked reaction flask. Heat under reflux at 120℃ for 30min, then cool to precipitate the solid. Filter to obtain the crude product. Recrystallize the crude product from ethanol to synthesize unsaturated nitrazole.

[0057] A4. Select a 500mL laboratory reactor equipped with a thermometer, stirrer, reflux condenser, and inert gas inlet pipe. Purge the air in the reactor with nitrogen through the inert gas inlet pipe. Add 100mL of deionized water, 30g of unsaturated azole, 3.5g of sodium persulfate (initiator), 5g of thiol, 24g of sodium methyl propylene sulfonate, and 23.2g of fumaric acid sequentially to the reactor, mix well, and obtain the reaction system. Heat the laboratory reactor to 90℃ and react at this temperature for 6 hours. After the reaction is complete, obtain the product. Adjust the pH of the product to 8 using 0.2mol / L NaOH solution, then add 10g of inorganic pour point depressant sodium nitrate and mix well to obtain a compound pour point depressant.

[0058] Example 4

[0059] This embodiment provides a method for preparing chitosan vanillin Schiff base for a low-chlorine composite environmentally friendly coal transportation antifreeze agent, including the following steps:

[0060] 3.22 g of chitosan was placed in a 250 mL round-bottom flask, and then 50 mL of methanol and 1 mL of acetic acid were added to swell the mixture for 2 hours, yielding mixture A. 3.04 g of vanillin was dissolved in 50 mL of methanol to obtain mixture B. All of mixture B was added to mixture A, and the mixture was reacted at 120 °C for 10 hours to obtain the product. The methanol was removed by rotary evaporation, and the chitosan vanillin Schiff base was synthesized.

[0061] Example 5

[0062] This embodiment provides a method for preparing a modified corrosion inhibitor for a low-chlorine composite environmentally friendly coal transportation antifreeze agent, including the following steps:

[0063] A 0.01 mol / L potassium thiocyanate solution in ethyl acetate was prepared. 10 mL of the potassium thiocyanate solution was added to a 250 mL four-necked flask, followed by 2.8 g of benzoyl chloride and 2 g of the chitosan vanillin Schiff base prepared in Example 4. The mixture was stirred to obtain the reactant. The reactant was reacted at 50 °C for 2 h, then filtered to remove the generated potassium chloride, and the filtrate was collected. The filtrate was cooled and recrystallized to prepare the modified corrosion inhibitor.

[0064] Example 6

[0065] This embodiment provides a method for preparing a modified corrosion inhibitor for a low-chlorine composite environmentally friendly coal transportation antifreeze agent, including the following steps:

[0066] A 0.015 mol / L potassium thiocyanate solution in ethyl acetate was prepared. 17 mL of the potassium thiocyanate solution in ethyl acetate was added to a 250 mL four-necked flask, followed by 4.2 g of benzoyl chloride and 3.5 g of the chitosan vanillin Schiff base prepared in Example 4. The mixture was stirred to obtain the reactant. The reactant was reacted at 55 °C for 2.2 h, then filtered to remove the generated potassium chloride, and the filtrate was collected. The filtrate was cooled and recrystallized to prepare the modified corrosion inhibitor.

[0067] Example 7

[0068] This embodiment provides a method for preparing a modified corrosion inhibitor for a low-chlorine composite environmentally friendly coal transportation antifreeze agent, including the following steps:

[0069] A 0.02 mol / L potassium thiocyanate solution in ethyl acetate was prepared. 20 mL of the potassium thiocyanate solution in ethyl acetate was added to a 250 mL four-necked flask, followed by 5.6 g of benzoyl chloride and 5 g of the chitosan vanillin Schiff base prepared in Example 4. The mixture was stirred to obtain the reactant. The reactant was reacted at 60 °C for 3 h, then filtered to remove the generated potassium chloride, and the filtrate was collected. The filtrate was cooled and recrystallized to prepare the modified corrosion inhibitor.

[0070] Example 8

[0071] This embodiment provides a method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation, including the following steps:

[0072] S1. According to the weight, 40 parts of the compound pour point depressant prepared in Example 1, 5 parts of the modified corrosion inhibitor prepared in Example 5, and 0.05 parts of guar gum are mixed to obtain component A.

[0073] S2. According to the weight, 45.05 parts of component A and 40 parts of industrial water are added to a stirred reactor and stirred at 100 r / min for 1 h, then allowed to stand for 15 min to obtain the backup liquid; the backup liquid is stirred at 100 r / min for 1 h and then cooled to room temperature to prepare a low-chlorine environmentally friendly coal transportation antifreeze agent.

[0074] Example 9

[0075] This embodiment provides a method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation, including the following steps:

[0076] S1. According to the weight, 50 parts of the compound pour point depressant prepared in Example 2, 8 parts of the modified corrosion inhibitor prepared in Example 6, and 0.08 parts of guar gum are mixed to obtain component A.

[0077] S2. According to the weight, 58 parts of component A and 45 parts of industrial water are added to the stirred reactor and stirred at 132 r / min for 1.6 h, then allowed to stand for 16 min to obtain the backup liquid; the backup liquid is stirred at 140 r / min for 1.5 h to prepare the low-chlorine environmentally friendly coal transportation antifreeze agent.

[0078] Example 10

[0079] This embodiment provides a method for preparing a low-chlorine composite environmentally friendly antifreeze agent for coal transportation, including the following steps:

[0080] S1. According to the weight, 60 parts of the compound pour point depressant prepared in Example 3, 10 parts of the modified corrosion inhibitor prepared in Example 7, and 0.1 parts of guar gum are mixed to obtain component A.

[0081] S2. According to the weight, 70.1 parts of component A and 50 parts of industrial water are added to a stirred reactor and stirred at 200 r / min for 2 h, then allowed to stand for 20 min to obtain the backup liquid; the backup liquid is stirred at 200 r / min for 2 h to prepare a low-chlorine environmentally friendly coal transportation antifreeze agent.

[0082] Comparative Example 1

[0083] The method for preparing the compound pour point depressant in this comparative example differs from that in Example 10. The preparation method of the compound pour point depressant in this comparative example is as follows:

[0084] A1. A 250 mL three-necked reaction flask was selected, equipped with a stirrer and a reflux condenser. 14 g of triazole, 100 mL of acetone, 5 g of potassium carbonate, and 24.5 g of ethyl chloroacetate were added to the flask and mixed thoroughly to obtain the reactants. The reactants were heated to 65 °C and refluxed at this temperature for 12 h. The mixture was then filtered under reduced pressure to obtain the filtrate. The filtrate was distilled under reduced pressure at 40 °C to remove the acetone, yielding intermediate A.

[0085] A2. Add 100 mL of deionized water, 25 g of intermediate A, 10 g of hydrazine hydrate, 21.2 g of benzaldehyde, 3.5 g of solid sodium persulfate (initiator), 5 g of thiol, 24 g of sodium methyl propylene sulfonate, and 23.2 g of fumaric acid sequentially to a reaction vessel. Mix well to obtain the reaction system. Heat the laboratory reaction vessel to 90 °C and react at this temperature for 6 hours. After the reaction is complete, the product is obtained. Adjust the pH of the product to 8 using 0.2 mol / L NaOH solution, then add 10 g of magnesium nitrate (an inorganic pour point depressant) and mix well to obtain a compound pour point depressant.

[0086] Comparative Example 2

[0087] The method for preparing the compound pour point depressant in this comparative example differs from that in Example 10. The preparation method of the compound pour point depressant in this comparative example is as follows:

[0088] A1. A 250 mL three-necked reaction flask was selected, equipped with a stirrer and a reflux condenser. 14 g of triazole, 100 mL of acetone, 5 g of potassium carbonate, and 24.5 g of ethyl chloroacetate were added to the flask and mixed thoroughly to obtain the reactants. The reactants were heated to 65 °C and refluxed at this temperature for 12 h. The mixture was then filtered under reduced pressure to obtain the filtrate. The filtrate was distilled under reduced pressure at 40 °C to remove the acetone, yielding intermediate A.

[0089] A2. Weigh 25g of intermediate A and 100mL of ethanol and add them to a 250mL three-necked reaction flask. Then add 10g of hydrazine hydrate and reflux at 200r / min and 80℃ for 12h to obtain a reaction solution. Distill the reaction solution to remove ethanol, and obtain a residue. Cool the residue to room temperature naturally, and a solid will precipitate. Filter the solid, wash it with deionized water, and dry it at 85℃ to constant weight to obtain intermediate B.

[0090] A3. Weigh 35g of intermediate B, 21.2g of benzaldehyde and 100mL of acetic acid and add them to a 250mL three-necked reaction flask. Heat under reflux at 120℃ for 30min, then cool to precipitate the solid. Filter to obtain the crude product. Recrystallize the crude product from ethanol to synthesize unsaturated nitrazole.

[0091] A4. Mix 100mL of deionized water, 30g of unsaturated azole, 24g of sodium methyl methacrylate sulfonate and 23.2g of fumaric acid to obtain the compound pour point depressant.

[0092] Comparative Example 3

[0093] The method for preparing the modified corrosion inhibitor in this comparative example differs from that in Example 10. The preparation method of the modified corrosion inhibitor in this comparative example is as follows:

[0094] A 0.02 mol / L potassium thiocyanate solution in ethyl acetate was prepared. 20 mL of the potassium thiocyanate solution was added to a 250 mL four-necked flask, followed by 5.6 g of benzoyl chloride and 5 g of chitosan. The mixture was stirred to obtain the reactant. The reactant was reacted at 60 °C for 3 h, then filtered to remove the generated potassium chloride, and the filtrate was collected. The filtrate was cooled and recrystallized to prepare the modified corrosion inhibitor.

[0095] Performance testing:

[0096] 1. According to SH / T0068-2002 "Determination of density or relative density of engine coolant and its concentrate", the density values ​​of the low-chlorine composite environmentally friendly coal transportation antifreeze prepared in Examples 8-10 and Comparative Examples 1-3 were measured sequentially; according to GB / T5561-2012 "Method for determining viscosity and flow properties of surfactants using a rotational viscometer", the viscosity values ​​of the low-chlorine composite environmentally friendly coal transportation antifreeze prepared in Examples 8-10 and Comparative Examples 1-3 at 20°C were tested sequentially.

[0097] 2. In accordance with JB / T7901-1999 "Metallic Materials Laboratory Uniform Corrosion Full Immersion Test Method", the corrosivity of the low-chlorine composite environmentally friendly coal transportation antifreeze prepared in Examples 8-10 and Comparative Examples 1-3 to copper, steel and aluminum was tested.

[0098] 3. According to SH / T0090-1991 "Determination of Freezing Point of Engine Coolant", the freezing point and boiling point of the low-chlorine composite environmentally friendly coal transportation antifreeze prepared in Examples 8-10 and Comparative Examples 1-3 were tested in sequence; the specific test results are shown in the table below.

[0099] Table 1. Sample Data and Performance Testing

[0100] Group item Example 8 Example 9 Example 10 Comparative Example 1 Comparative Example 2 Comparative Example 3 Density / (g / cm 3 )]]> 1.365 1.387 1.401 1.511 1.456 1.398 Viscosity / (mPa-s) 11.88 12.03 12.21 13.06 12.51 12.19 Freezing point / (°C) -52 -55 -57 -42 -43 -46 Boiling point / (°C) 108 110 113 99 101 105 Corrosivity to steel / (mm / a) 0.0006 0.0004 0.0003 0.0008 0.0007 0.0009 Corrosivity to copper / (mm / a) 0.05 0.03 0.02 0.06 0.07 0.08 Corrosivity to aluminum / (mm / a) 0.006 0.004 0.003 0.007 0.008 0.009

[0101] Data Analysis: Analyzing the data in Table 1, the antifreeze prepared in Examples 8-10 of this invention all have moderate density and viscosity values, and good flowability. However, in Comparative Example 1, the same mass of unsaturated nitrile, sodium methallyl sulfonate, and fumaric acid were mixed as a compound pour point depressant; in Comparative Example 2, the same mass of unsaturated nitrile, sodium methallyl sulfonate, and fumaric acid were mixed as a compound pour point depressant. The density and viscosity values ​​of the compound pour point depressants prepared in Comparative Examples 1 and 2 were significantly increased. Excessively high density and viscosity are not conducive to the flow of the compound pour point depressant and are not conducive to the spraying of antifreeze.

[0102] The antifreeze prepared in Examples 8-10 of this invention all have low freezing points and high boiling points, exhibiting good antifreeze performance. Because the performance of the compound pour point depressants prepared in Comparative Examples 1 and 2 is inferior to that used in Examples 8-10, the freezing point and boiling point of the antifreeze prepared in Comparative Examples 1 and 2 increase. In Comparative Example 3, when the modified corrosion inhibitor was prepared by replacing chitosan vanillin Schiff base with the same mass of chitosan, the antifreeze performance of the prepared antifreeze also decreased, with the freezing point increasing and the boiling point decreasing.

[0103] The antifreeze prepared in Examples 8-10 of this invention exhibits good anti-corrosion performance against metals, showing low corrosion values ​​for steel, copper, and aluminum. However, due to the deterioration in the performance of the compound pour point depressant prepared in Comparative Examples 1-2 and the modified corrosion inhibitor prepared in Comparative Example 3, the antifreeze prepared in these examples shows a decrease in its anti-corrosion performance against metals and an increase in its corrosion resistance value.

[0104] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0105] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0106] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a low-chlorine composite environment-friendly coal transportation antifreezing agent, characterized in that, It comprises the following steps: S1, compounding the freezing point depressant, the modified corrosion inhibitor and the thickening stabilizer, mixing uniformly to obtain component A; S2, mixing, stirring and standing the component A and industrial water to obtain a backup liquid; the backup liquid is continuously stirred to prepare a low-chlorine composite environment-friendly coal transportation antifreezing agent; The compounding freezing point depressant comprises inorganic freezing point depressant and organic freezing point depressant, the organic freezing point depressant is obtained by reaction of unsaturated nitrogen azole, sodium methacryl sulfonate and fumaric acid; the unsaturated nitrogen azole is obtained by reaction of intermediate B and benzaldehyde, the intermediate B is obtained by reaction of the following steps: A1, mixing triazole, acetone, potassium carbonate and ethyl chloroacetate uniformly to obtain reactants; heating the reactants to 58-65 DEG C, refluxing at this temperature for 10-12 h, then reducing pressure and filtering to obtain filtrate; distilling the filtrate to obtain intermediate A; A2, adding intermediate A into ethanol, then adding hydrazine hydrate, refluxing at 75-80 DEG C for 10-12 h to obtain reaction liquid; processing the reaction liquid to obtain intermediate B; The modified corrosion inhibitor is obtained by reaction of potassium thiocyanate, benzoyl chloride and chitosan vanillin Schiff base.

2. The preparation method of the low-chlorine composite environment-friendly coal transportation antifreeze according to claim 1, characterized in that, The preparation method of the compounding freezing point depressant comprises the following steps: A1, mixing triazole, acetone, potassium carbonate and ethyl chloroacetate uniformly to obtain reactants; heating the reactants to 58-65 DEG C, refluxing at this temperature for 10-12 h, then reducing pressure and filtering to obtain filtrate; distilling the filtrate to obtain intermediate A; A2, adding intermediate A into ethanol, then adding hydrazine hydrate, refluxing at 75-80 DEG C for 10-12 h to obtain reaction liquid; processing the reaction liquid to obtain intermediate B; A3, mixing intermediate B, benzaldehyde and acetic acid, heating and refluxing at 105-120 DEG C for 20-30 min, then cooling, precipitating solid, filtering to obtain crude product; recrystallizing the crude product with acetic acid to synthesize unsaturated nitrogen azole; A4, mixing deionized water, unsaturated nitrogen azole, initiator, mercaptan, sodium methacryl sulfonate, fumaric acid and inorganic freezing point depressant uniformly under inert gas atmosphere to obtain reaction system; reacting the reaction system at 80-90 DEG C for 3-6 h, after the reaction is completed, obtaining product; adjusting the pH value of the product to 7-8 with NaOH solution, then doping inorganic freezing point depressant to obtain compounding freezing point depressant.

3. The preparation method of the low-chlorine composite environment-friendly coal transportation antifreeze according to claim 2, characterized in that, In step A1, the amount ratio of triazole, acetone, potassium carbonate and ethyl chloroacetate is 7-14 g:100 mL:3-5 g:12.2-24.5 g; the distillation temperature of the filtrate is 35-40 DEG C.

4. The preparation method of the low-chlorine composite environment-friendly coal transportation antifreeze according to claim 2, characterized in that, In step A2, the amount ratio of intermediate A, ethanol and hydrazine hydrate is 15-25 g:100 mL:5-10 g.

5. The preparation method of the low-chlorine composite environment-friendly coal transportation antifreeze according to claim 2, characterized in that, In step A3, the amount ratio of intermediate B, benzaldehyde and acetic acid is 5-35 g:10.6-21.2 g:100 mL.

6. The preparation method of the low-chlorine composite environment-friendly coal transportation antifreeze of claim 2, characterized in that, In step A4, the amount ratio of deionized water, unsaturated nitrogen azole, initiator, mercaptan, sodium methacryl sulfonate, fumaric acid and inorganic freezing point depressant is 50-100 mL:20-30 g:1.5-3.5 g:1-5 g:12-24 g:11.6-23.2 g:3-10 g.

7. The preparation method of the low-chlorine composite environment-friendly coal transportation antifreeze according to claim 1, characterized in that, The preparation method of the modified corrosion inhibitor comprises the following steps: The ethyl acetate solution of potassium thiocyanate, benzoyl chloride and chitosan vanillin Schiff base are mixed to obtain reactants; the reactants are reacted at 50-60 DEG C for 2-3 h, and then filtered to remove the generated potassium chloride, and the filtrate is collected; the filtrate is cooled and recrystallized to obtain the modified corrosion inhibitor.

8. The preparation method of the low-chlorine composite environment-friendly coal transportation antifreeze according to claim 7, characterized in that, The concentration of the ethyl acetate solution of potassium thiocyanate is 0.01-0.02 mol / L; the amount ratio of the ethyl acetate solution of potassium thiocyanate, benzoyl chloride and chitosan vanillin Schiff base is 10-20 mL:2.8-5.6 g:2-5 g.

9. The preparation method of the low-chlorine composite environment-friendly coal transportation antifreeze according to claim 1, characterized in that, In step S1, the weight ratio of the compounded pour point depressant, the modified corrosion inhibitor and the thickening stabilizer is 40-60:5-10:0.05-0.1; in step S2, the amount ratio of component A and industrial water is 45.05-70.1:40-50; in step S2, the mixing and stirring time of component A and industrial water is 1-2 h, and the standing time is 15-20 min; the stirring time of the backup liquid is 1-2 h.

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