Preparation method of low-chlorine composite environment-friendly coal transportation anti-freezing agent

Abstract

The invention discloses a preparation method of a low-chlorine composite environment-friendly coal transportation anti-freezing agent, and belongs to the technical field of anti-freezing solutions. The anti-freezing solution is used for solving the technical problems of complex components and poor anti-freezing and metal corrosion resistance of the anti-freezing solution for coal transportation in the prior art. The preparation method of the low-chlorine composite environment-friendly coal transportation anti-freezing agent comprises the following step: uniformly mixing the compound pour point depressant, the modified corrosion inhibitor, the thickening stabilizer and the industrial water to prepare the low-chlorine composite environment-friendly coal transportation anti-freezing agent. The compound pour point depressant comprises an organic pour point depressant and an inorganic pour point depressant; the organic pour point depressant is obtained by reacting unsaturated azole, sodium methallyl sulfonate and fumaric acid; the unsaturated nitrogen is obtained by reaction of an intermediate B and benzaldehyde, and the intermediate B is obtained by reaction of triazole and ethyl chloroacetate; the modified corrosion inhibitor is obtained by carrying out a reaction on potassium thiocyanate, benzoyl chloride and chitosan vanillin Schiff base. The anti-freezing solution prepared by the invention has the advantages of moderate fluidity, good metal corrosion resistance and good anti-freezing performance.

Description

Technical Field

[0001] The present invention relates to the technical field of antifreeze fluids, and in particular to a method for preparing a low-chlorine composite environmentally friendly coal transportation antifreeze. Background Art

[0002] Coal cargo is prone to freezing during loading, unloading, storage, and transportation in winter, making it difficult to load and unload. This not only impacts production but also severely reduces vehicle turnover efficiency. Using chemical antifreeze agents with excellent antifreeze and thawing properties to address the problem of frozen coal unloading can not only significantly reduce the freezing strength of coal but also be very effective in tackling winter transportation of coal or granular cargo. Patent application CN1261522C discloses a highly effective antifreeze agent for coal transportation and its preparation method. The antifreeze agent comprises ethylene glycol, calcium chloride, triethanolamine, and deionized water. This polyhydric alcohol mixture provides an antifreeze effect by weakening the hydrogen bonding forces between water molecules. However, antifreeze agents composed of low molecular weight polyols suffer from low density and viscosity, high fluidity, and a lack of corrosion protection against metals. Furthermore, the high chlorine content of these antifreeze agents can easily cause rust and corrosion in coal-burning equipment, transportation equipment, and spraying equipment.

[0003] Chlorine-free antifreeze for coal transportation consists primarily of C, H, and O, with no other harmful elements, and poses no corrosion risk to nonferrous metals. Patent application CN113046026A discloses a chlorine-free, low-corrosive coal antifreeze. The antifreeze comprises an antifreeze agent, a wall-cling agent, an organic preservative, an organic corrosion inhibitor, an organic surfactant, and water. The coal transportation antifreeze contains no chlorine or inorganic salts. The organic corrosion inhibitor is benzotriazole, the antifreeze agent is diethylene glycol diglycidyl ether or diethylene glycol dimethyl ether, and the wall-cling agent is an aqueous glue derived from animal or plant colloids. However, the antifreeze has a complex composition and exhibits poor corrosion and antifreeze properties.

[0004] In view of the technical defects in this aspect, a solution is now proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a low-chlorine composite environmentally friendly coal transportation antifreeze, which is used to solve the technical problems of the prior art such as complex antifreeze composition and poor antifreeze and anti-metal corrosion properties.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

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

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

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

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

[0011] The composite pour point depressant is obtained by reacting unsaturated azole, sodium methacrylic acid and fumaric acid; the unsaturated azole is obtained by reacting intermediate B and benzaldehyde, and the intermediate B is obtained by reacting triazole and 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 comprises the following steps:

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

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

[0016]

[0017] A2, adding intermediate A to ethanol, then adding hydrazine hydrate, and reflux reaction at 75-80 ° C for 10-12 hours to obtain a reaction solution; the reaction solution is subjected to post-processing to prepare intermediate B;

[0018] Using ethanol as the solvent, the hydrazine group of hydrazine hydrate attacks the carbonyl carbon of the ester group to form a tetrahedral intermediate, and ethanol is removed as a leaving group to generate a hydrazide structure; the reaction formula for the reaction of intermediate A and hydrazine hydrate to obtain intermediate B is as follows:

[0019]

[0020] A3, intermediate B, benzaldehyde and acetic acid were mixed, heated under reflux at 105-120°C for 20-30 min, cooled, solids precipitated, and filtered to obtain a crude product; the crude product was recrystallized from acetic acid to synthesize an unsaturated nitrogen azole;

[0021] Intermediate B reacts with benzaldehyde to form a hydrazone bond, and the reaction formula is as follows:

[0022]

[0023] A4. Under an inert gas atmosphere, deionized water, unsaturated nitrogen azole, initiator, mercaptan, sodium methyl propylene sulfonate, and fumaric acid are mixed to obtain a reaction system; the reaction system is reacted at 80-90° C. for 3-6 hours to obtain a product; and the pH value of the product is adjusted to 7-8 using a NaOH solution to obtain a composite pour point depressant.

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

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

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

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

[0028] Furthermore, 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 amount ratio of deionized water, unsaturated nitrogen azole, initiator, mercaptan, sodium methyl propene sulfonate, fumaric acid and inorganic pour 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.

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

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

[0031] Potassium thiocyanate and benzoyl chloride undergo 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 usage 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] Furthermore, in step S1, the weight ratio of the compound pour point depressant, the modified corrosion inhibitor and the thickening stabilizer is 40-60:5-10:0.05-0.1; in step S2, the usage ratio of component A and industrial water is 45.05-70.1:40-50; in step S2, component A and industrial water are mixed and stirred for 1-2 hours and allowed to stand for 15-20 minutes; and the reserve liquid is stirred for 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 structures of unsaturated azoles include five-membered heterocyclic aromatic compounds and imine structures. In the heterocyclic structure, the nitrogen atom's lone electron pair is delocalized, forming coordination bonds with vacant d orbitals in the metal orbital. This allows the unsaturated azole to adsorb on the metal surface, reducing rust and corrosion. Sodium methyl propylene sulfonate and fumaric acid, under the action of an initiator, undergo free radical addition polymerization, forming a product that can form a hydrogen bond network with the moisture in the coal. The imine structure of the unsaturated azole reacts with the carboxyl group in the fumaric acid to form a composite pour point depressant with a long molecular chain. This steric effect can disrupt the arrangement of ice crystals, enhancing its own pour point depressant effect. Furthermore, the long molecular chain composite pour point depressant can increase the viscosity of the coal-water mixture and increase intermolecular friction, thereby imparting a certain degree of friction and viscosity to antifreeze agents with simple doping components. The compound pour point depressant is also doped with a small amount of inorganic pour point depressant. Through the synergistic effect between the organic pour point depressant and the inorganic pour point depressant, the freezing point can be better lowered, thereby achieving a better pour point depressing effect.

[0036] 2. Chitosan modification can form chitosan vanillin Schiff bases containing C=N double bonds. Chitosan vanillin Schiff bases structurally meet the requirements of a good corrosion inhibitor. Furthermore, they are non-toxic to the environment and can be completely degraded by microorganisms and fungi, making them an environmentally friendly, green, slow-release agent. The acylthiourea structure formed by the chitosan vanillin Schiff base reacting with potassium thiocyanate can form a relatively tight adsorption to metal surfaces, forming a protective film on the metal surface. This impedes corrosive media and enhances the slow-release effect.

[0037] 3. To avoid the crystal precipitation problem associated with the aforementioned single-component antifreeze, the antifreeze prepared in the present invention also incorporates a small amount of guar gum, a thickening and stabilizing agent. Guar gum, rich in hydroxyl groups, not only has a thickening effect but also forms a hydrogen bond network with water molecules in the coal, disrupting the ordered structure of the water molecules within the liquid and enhancing antifreeze performance. The antifreeze for coal transportation prepared in the present invention has a simple composition consisting of only industrial water, a compounded pour point depressant, a modified corrosion inhibitor, and the thickening and stabilizing agent guar gum. It is chlorine-free, harmless, and has excellent antifreeze and corrosion resistance. DETAILED DESCRIPTION

[0038] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] The guar gum used in Examples 8-10 of the present invention was purchased from Guangdong Ousman Biotechnology Co., Ltd., and the 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, comprising the following steps:

[0042] A1. Prepare a 250 mL three-necked reaction flask equipped with a stirrer and reflux condenser. Add 7 g of triazole, 100 mL of acetone, 3 g of potassium carbonate, and 12.2 g of ethyl chloroacetate to the flask and mix thoroughly to obtain a reactant. Heat the reactant to 58°C and reflux for 10 hours. Then, filter under reduced pressure to obtain a filtrate. Distill the filtrate under reduced pressure at 35°C to remove the acetone, yielding Intermediate A.

[0043] A2. Weigh 15 g of Intermediate A and 100 mL of ethanol into a 250 mL three-necked reaction flask. Then, add 5 g of hydrazine hydrate and reflux at 75°C at 100 rpm for 10 h to obtain a reaction solution. Ethanol was removed from the reaction solution by distillation to obtain a residual liquid. The residual liquid was naturally cooled to room temperature to precipitate a solid. The solid was filtered, washed with deionized water, and dried at 75°C to constant weight to obtain Intermediate B.

[0044] A3. Weigh 15 g of intermediate B, 10.6 g of benzaldehyde, and 100 mL of acetic acid into a 250 mL three-necked reaction flask, heat under reflux at 105° C. for 20 min, then cool to precipitate a solid, filter, and obtain a crude product; the crude product is recrystallized from ethanol to synthesize an unsaturated nitrogen azole.

[0045] A4. Prepare a 500mL laboratory reactor equipped with a thermometer, stirrer, reflux condenser, and inert gas inlet. Displace the air in the reactor with nitrogen introduced through the inert gas inlet. Add 50mL of deionized water, 20g of unsaturated nitrogen azole, 1.5g of solid sodium persulfate (initiator), 1g of mercaptan, 12g of sodium methylpropene sulfonate, and 11.6g of fumaric acid to the reactor in sequence and mix thoroughly to obtain a reaction system. Heat the laboratory reactor to 80°C and allow the reaction to proceed at this temperature for 3 hours. After completion of the reaction, the product is obtained. The pH of the product is adjusted to 7 using 0.1mol / L NaOH solution, then doped with 3g of magnesium nitrate (an inorganic pour point depressant) and mixed thoroughly to obtain a composite 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, comprising the following steps:

[0048] A1. Prepare a 250 mL three-necked reaction flask equipped with a stirrer and reflux condenser. Add 12 g of triazole, 100 mL of acetone, 4 g of potassium carbonate, and 18.5 g of ethyl chloroacetate to the flask and mix thoroughly to obtain a reactant. Heat the reactant to 62°C, reflux at this temperature for 11 hours, and then filter under reduced pressure to obtain a filtrate. Distill the filtrate under reduced pressure at 38°C to remove the acetone, obtaining Intermediate A.

[0049] A2. Weigh 20 g of Intermediate A and 100 mL of ethanol into a 250 mL three-necked reaction flask. Then, add 8 g of hydrazine hydrate. Reflux at 77°C at 150 rpm for 11 h to obtain a reaction solution. Ethanol is removed from the reaction solution by distillation to obtain a residual liquid. The residual liquid is naturally cooled to room temperature to precipitate a solid. The solid is filtered, washed with deionized water, and dried at 80°C to constant weight to obtain Intermediate B.

[0050] A3. Weigh 25 g of intermediate B, 15.6 g of benzaldehyde, and 100 mL of acetic acid into a 250 mL three-necked reaction flask, heat under reflux at 110° C. for 25 min, then cool to precipitate a solid, filter, and obtain a crude product; the crude product is recrystallized from ethanol to synthesize an unsaturated nitrogen azole.

[0051] A4. Prepare a 500mL laboratory reactor equipped with a thermometer, stirrer, reflux condenser, and inert gas inlet. Displace the air in the reactor with nitrogen introduced through the inert gas inlet. Add 80mL of deionized water, 25g of unsaturated nitrogen azole, 2.5g of solid sodium persulfate (initiator), 3g of mercaptan, 18g of sodium methylpropene sulfonate, and 17.4g of fumaric acid to the reactor in sequence and mix thoroughly to obtain a reaction system. Heat the laboratory reactor to 85°C and allow the reaction to proceed at this temperature for 5 hours. After completion of the reaction, the product is obtained. The pH of the product is adjusted to 7.7 using 0.15mol / L NaOH solution. Then, 5g of calcium nitrate (an inorganic pour point depressant) is added and mixed thoroughly to obtain a composite 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, comprising the following steps:

[0054] A1. Prepare a 250 mL three-necked reaction flask equipped with a stirrer and reflux condenser. Add 14 g of triazole, 100 mL of acetone, 5 g of potassium carbonate, and 24.5 g of ethyl chloroacetate to the flask and mix thoroughly to obtain a reactant. Heat the reactant to 65°C, reflux at this temperature for 12 hours, and then filter under reduced pressure to obtain a filtrate. Distill the filtrate under reduced pressure at 40°C to remove the acetone, obtaining Intermediate A.

[0055] A2. Weigh 25 g of Intermediate A and 100 mL of ethanol into a 250 mL three-necked reaction flask. Then, add 10 g of hydrazine hydrate. Reflux the mixture at 200 rpm and 80°C for 12 h to obtain a reaction solution. Ethanol is removed from the reaction solution by distillation to obtain a residual liquid. The residual liquid is naturally cooled to room temperature to precipitate a solid. The solid is filtered, washed with deionized water, and dried at 85°C to constant weight to obtain Intermediate B.

[0056] A3. Weigh 35 g of intermediate B, 21.2 g of benzaldehyde, and 100 mL of acetic acid into a 250 mL three-necked reaction flask, heat under reflux at 120° C. for 30 min, then cool to precipitate a solid, filter, and obtain a crude product; the crude product is recrystallized from ethanol to synthesize an unsaturated nitrogen azole.

[0057] A4. Prepare a 500mL laboratory reactor equipped with a thermometer, a stirrer, a reflux condenser, and an inert gas inlet. Displace the air in the reactor with nitrogen introduced through the inert gas inlet. Add 100mL of deionized water, 30g of unsaturated nitrogen azole, 3.5g of solid sodium persulfate (initiator), 5g of mercaptan, 24g of sodium methyl propylene sulfonate, and 23.2g of fumaric acid to the reactor in sequence and mix thoroughly to obtain a reaction system. Heat the laboratory reactor to 90°C and allow the reaction to proceed at this temperature for 6 hours. After completion of the reaction, the product is obtained. The pH of the product is adjusted to 8 using 0.2mol / L NaOH solution, then doped with 10g of sodium nitrate (an inorganic pour point depressant) and mixed thoroughly to obtain a composite pour point depressant.

[0058] Example 4

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

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

[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, comprising the following steps:

[0063] Prepare a 0.01 mol / L potassium thiocyanate solution in ethyl acetate. Add 10 mL of this solution to a 250 mL four-necked flask. Then, add 2.8 g of benzoyl chloride and 2 g of the chitosan vanillin Schiff base prepared in Example 4 to the flask and mix thoroughly to obtain a reactant. The reactant is reacted at 50°C for 2 hours, then filtered to remove the generated potassium chloride, and the filtrate is collected. The filtrate is cooled and recrystallized to prepare a 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, comprising the following steps:

[0066] Prepare a 0.015 mol / L potassium thiocyanate solution in ethyl acetate. Add 17 mL of this solution to a 250 mL four-necked flask. Then, add 4.2 g of benzoyl chloride and 3.5 g of the chitosan vanillin Schiff base prepared in Example 4 to the flask and mix thoroughly to obtain a reactant. The reactant is reacted at 55°C for 2.2 hours, then filtered to remove the generated potassium chloride, and the filtrate is collected. The filtrate is cooled and recrystallized to prepare a 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, comprising the following steps:

[0069] Prepare a 0.02 mol / L potassium thiocyanate solution in ethyl acetate. Add 20 mL of this solution to a 250 mL four-necked flask. Then, add 5.6 g of benzoyl chloride and 5 g of the chitosan vanillin Schiff base prepared in Example 4 to the flask and mix thoroughly to obtain a reactant. The reactant is reacted at 60°C for 3 hours, then filtered to remove the generated potassium chloride, and the filtrate is collected. The filtrate is cooled and recrystallized to prepare a modified corrosion inhibitor.

[0070] Example 8

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

[0072] S1. According to parts by weight, 40 parts of the composite 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 were mixed to obtain component A.

[0073] S2. According to parts by weight, 45.05 parts of component A and 40 parts of industrial water were added to a stirred reactor, stirred at 100 r / min for 1 hour, and then allowed to stand for 15 minutes to obtain a reserve solution; the reserve solution was further stirred at 100 r / min for 1 hour, and then cooled to room temperature to prepare a low-chlorine environmentally friendly coal transportation antifreeze.

[0074] Example 9

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

[0076] S1. According to parts by 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 were mixed to obtain component A.

[0077] S2. According to parts by weight, 58 parts of component A and 45 parts of industrial water were added to a stirred reactor, stirred at 132 r / min for 1.6 hours, and then allowed to stand for 16 minutes to obtain a reserve solution; the reserve solution was further stirred at 140 r / min for 1.5 hours to prepare a low-chlorine environmentally friendly coal transportation antifreeze.

[0078] Example 10

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

[0080] S1. According to parts by 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 were mixed to obtain component A.

[0081] S2. According to parts by weight, 70.1 parts of component A and 50 parts of industrial water were added to a stirred reactor, stirred at 200 r / min for 2 hours, and then allowed to stand for 20 minutes to obtain a reserve solution; the reserve solution was further stirred at 200 r / min for 2 hours to prepare a low-chlorine environmentally friendly coal transportation antifreeze.

[0082] Comparative Example 1

[0083] Compared with Example 10, the method for preparing the compound pour point depressant in this comparative example is different. The preparation method of the compound pour point depressant in this comparative example is as follows:

[0084] A1. Prepare a 250 mL three-necked reaction flask equipped with a stirrer and reflux condenser. Add 14 g of triazole, 100 mL of acetone, 5 g of potassium carbonate, and 24.5 g of ethyl chloroacetate to the flask and mix thoroughly to obtain a reactant. Heat the reactant to 65°C, reflux at this temperature for 12 hours, and then filter under reduced pressure to obtain a filtrate. Distill the filtrate under reduced pressure at 40°C to remove the acetone, obtaining Intermediate A.

[0085] A2. To a reactor, 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 mercaptan, 24 g of sodium methyl propylene sulfonate, and 23.2 g of fumaric acid were added in sequence and mixed to obtain a reaction system. The laboratory reactor was heated to 90°C and reacted at this temperature for 6 h. After completion of the reaction, a product was obtained. The pH of the product was adjusted to 8 using 0.2 mol / L NaOH solution, and then 10 g of magnesium nitrate (an inorganic pour point depressant) was added and mixed to obtain a composite pour point depressant.

[0086] Comparative Example 2

[0087] Compared with Example 10, the method for preparing the compound pour point depressant in this comparative example is different. The preparation method of the compound pour point depressant in this comparative example is as follows:

[0088] A1. Prepare a 250 mL three-necked reaction flask equipped with a stirrer and reflux condenser. Add 14 g of triazole, 100 mL of acetone, 5 g of potassium carbonate, and 24.5 g of ethyl chloroacetate to the flask and mix thoroughly to obtain a reactant. Heat the reactant to 65°C, reflux at this temperature for 12 hours, and then filter under reduced pressure to obtain a filtrate. Distill the filtrate under reduced pressure at 40°C to remove the acetone, obtaining Intermediate A.

[0089] A2. Weigh 25 g of Intermediate A and 100 mL of ethanol into a 250 mL three-necked reaction flask. Then, add 10 g of hydrazine hydrate. Reflux the mixture at 200 rpm and 80°C for 12 h to obtain a reaction solution. Ethanol is removed from the reaction solution by distillation to obtain a residual liquid. The residual liquid is naturally cooled to room temperature to precipitate a solid. The solid is filtered, washed with deionized water, and dried at 85°C to constant weight to obtain Intermediate B.

[0090] A3. Weigh 35 g of intermediate B, 21.2 g of benzaldehyde, and 100 mL of acetic acid into a 250 mL three-necked reaction flask, heat under reflux at 120° C. for 30 min, then cool to precipitate a solid, filter, and obtain a crude product; the crude product is recrystallized from ethanol to synthesize an unsaturated nitrogen azole.

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

[0092] Comparative Example 3

[0093] Compared with Example 10, the method for preparing the modified corrosion inhibitor in this comparative example is different. The preparation method of the modified corrosion inhibitor in this comparative example is as follows:

[0094] Prepare a 0.02 mol / L potassium thiocyanate solution in ethyl acetate. Add 20 mL of this solution to a 250 mL four-necked flask. Then, add 5.6 g of benzoyl chloride and 5 g of chitosan to the flask and mix thoroughly to obtain a reactant. The reactant is reacted at 60°C for 3 hours, then filtered to remove the generated potassium chloride, and the filtrate is collected. The filtrate is cooled and recrystallized to prepare a modified corrosion inhibitor.

[0095] Performance testing:

[0096] 1. According to SH / T0068-2002 "Determination of density or relative density of engine coolants and their concentrates", 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 in turn; 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 in turn.

[0097] 2. According to JB / T7901-1999 "Metal Material Laboratory Uniform Corrosion Full Immersion Test Method", the corrosion 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 in turn.

[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 turn; the specific test results are shown in the table below.

[0099] Table 1. Sample data performance test

[0100] Group Project Example 8 Example 9 Example 10 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[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 / (℃) -52 -55 -57 -42 -43 -46 Boiling point / (℃) 108 110 113 99 101 105 Corrosion to steel / (mm / a) 0.0006 0.0004 0.0003 0.0008 0.0007 0.0009 Corrosion to copper / (mm / a) 0.05 0.03 0.02 0.06 0.07 0.08 Corrosion to aluminum / (mm / a) 0.006 0.004 0.003 0.007 0.008 0.009

[0101] Data Analysis: Analysis of the data in Table 1 shows that the antifreeze solutions prepared in Examples 8-10 of the present invention all have moderate density and viscosity values ​​and good fluidity. However, in Comparative Example 1, an equal mass of unsaturated azole, sodium methacrylate sulfonate, and fumaric acid were mixed to form a composite pour point depressant; and in Comparative Example 2, an equal mass of unsaturated azole, sodium methacrylate sulfonate, and fumaric acid were mixed to form a composite pour point depressant. The density and viscosity values ​​of the composite pour point depressants prepared in Comparative Examples 1 and 2 were significantly increased. Excessively high density and viscosity are detrimental to the flow of the composite pour point depressant and the spraying of the antifreeze solution.

[0102] The antifreeze solutions prepared in Examples 8-10 of the present invention all have low freezing points and high boiling points, and exhibit excellent antifreeze performance. Since the composite pour point depressants prepared in Comparative Examples 1 and 2 are inferior to those used in Examples 8-10, the freezing points of the antifreeze solutions prepared in Comparative Examples 1 and 2 increase and the boiling points decrease. In Comparative Example 3, when the modified corrosion inhibitor is prepared by replacing chitosan vanillin Schiff base with the same mass of chitosan, the antifreeze performance of the antifreeze solution also decreases, with the freezing point increasing and the boiling point decreasing.

[0103] The antifreeze solutions prepared in Examples 8-10 of the present invention exhibited excellent metal corrosion resistance, as demonstrated by low corrosion values ​​for steel, copper, and aluminum. However, due to the deterioration in the performance of the composite pour point depressants prepared in Comparative Examples 1-2 and the deterioration in the performance of the modified corrosion inhibitor prepared in Comparative Example 3, the antifreeze solutions exhibited poor metal corrosion resistance and increased corrosion values.

[0104] The above contents are merely examples and explanations of the structure of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0105] Throughout this specification, references to terms such as "one embodiment," "example," and "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0106] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a low-chlorine composite environmentally friendly coal transportation antifreeze, characterized in that: The following steps are involved: S1, mixing the composite pour point depressant, modified corrosion inhibitor and thickening stabilizer to obtain component A; S2. Component A and industrial water are mixed, stirred, and allowed to stand to obtain a reserve solution; the reserve solution is further stirred to prepare a low-chlorine composite environmentally friendly coal transportation antifreeze; The compound pour point depressant includes an inorganic pour point depressant and an organic pour point depressant, wherein the organic pour point depressant is obtained by reacting an unsaturated nitrogen azole, sodium methacrylic acid, and fumaric acid; the unsaturated nitrogen azole is obtained by reacting an intermediate B with benzaldehyde, and the 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.

2. The method for preparing a low-chlorine composite environmentally friendly coal transportation antifreeze according to claim 1, characterized in that: The preparation method of the composite pour point depressant comprises the following steps: A1, triazole, acetone, potassium carbonate and ethyl chloroacetate are mixed to obtain a reactant; the reactant is heated to 58-65°C, refluxed at this temperature for 10-12 hours, and then filtered under reduced pressure to obtain a filtrate; the filtrate is distilled to obtain intermediate A; A2, adding intermediate A to ethanol, then adding hydrazine hydrate, and reflux reaction at 75-80 ° C for 10-12 hours to obtain a reaction solution; the reaction solution is subjected to post-processing to prepare intermediate B; A3, intermediate B, benzaldehyde and acetic acid were mixed, heated under reflux at 105-120°C for 20-30 min, cooled, solids precipitated, and filtered to obtain a crude product; the crude product was recrystallized from acetic acid to synthesize an unsaturated nitrogen azole; A4. Under an inert gas atmosphere, deionized water, unsaturated nitrogen azole, initiator, mercaptan, sodium methyl propylene sulfonate, and fumaric acid are mixed to obtain a reaction system; the reaction system is reacted at 80-90° C. for 3-6 hours to obtain a product; the pH value of the product is adjusted to 7-8 using a NaOH solution, and then an inorganic pour point depressant is added to obtain a composite pour point depressant.

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

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

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

6. The method for preparing a low-chlorine composite environmentally friendly coal transportation antifreeze according to claim 2, characterized in that: In step A4, the usage ratio of deionized water, unsaturated nitrogen azole, initiator, mercaptan, sodium methyl propylene sulfonate, fumaric acid and inorganic pour 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 method for preparing a low-chlorine composite environmentally 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 a reactant; the reactant is placed at 50-60° C. for reaction for 2-3 hours, then filtered to remove generated potassium chloride, and a filtrate is collected; the filtrate is cooled and recrystallized to prepare a modified corrosion inhibitor.

8. The method for preparing a low-chlorine composite environmentally 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 usage 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 method for preparing a low-chlorine composite environmentally friendly coal transportation antifreeze according to claim 1, characterized in that: In step S1, the weight ratio of the compound pour point depressant, the modified corrosion inhibitor and the thickening stabilizer is 40-60:5-10:0.05-0.1; in step S2, the usage ratio of component A and industrial water is 45.05-70.1:40-50; in step S2, component A and industrial water are mixed and stirred for 1-2 hours and allowed to stand for 15-20 minutes; and the reserve liquid is stirred for 1-2 hours.

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