Coal pitch-based surfactant as well as preparation method and application thereof

Abstract

The invention discloses a coal pitch-based surfactant and a preparation method and application thereof, and belongs to the technical field of surfactants, coal pitch is used as a raw material, after impurity removal, a chlorosulfonic acid group is introduced on a benzene ring in a coal pitch molecular structure through sulfonylation reaction of chlorosulfonic acid and phosphorus oxychloride, and the coal pitch-based surfactant is obtained. Then sulfonate is generated through an esterification reaction between a chlorosulfonic acid group and a hydroxyl group at the upper end of a hydrophilic chain, the hydrophilic chain is introduced to the edge of a coal pitch molecular structure, surface activity is given to the coal pitch molecular structure, and the coal pitch-based surfactant containing hydrophobic aromatic rings and hydrophilic long chains at the same time is obtained. A central multi-aromatic ring structure of the coal pitch-based surfactant is highly similar to a surface structure of Shenhua coal, the central multi-aromatic ring structure and the surface structure of the Shenhua coal have relatively strong pi-pi action and hydrophobic action and are high in adsorption fastness, meanwhile, long hydrophilic chains grafted at the edge can effectively provide steric hindrance, a physical barrier is formed between adjacent coal particles, the coal particles are effectively prevented from being gathered, and the coal pitch-based surfactant has a good application prospect. The coal water slurry has relatively low viscosity and good dispersity and stability.

Description

Technical Field

[0001] The invention belongs to the technical field of surfactants, and in particular relates to a coal tar pitch-based surfactant and a preparation method and application thereof. Background Art

[0002] Coal tar is the residual residue after coal tar distillation, and its output accounts for about 50% to 60% of the total coal tar. With the development of the coking industry, a large amount of coal tar is underutilized, which seriously affects the comprehensive utilization efficiency of coal resources. Therefore, the use of new methods to develop universal and efficient coal tar can not only effectively alleviate the energy crisis, but also improve the overall economic and social benefits of the coal industry. At present, coal tar is mainly used to prepare electrodes, activated carbon, carbon fiber, needle coke, impregnants and road construction materials. However, since the structure and composition of coal tar are affected by the properties of raw coal, coking process, coal tar quality and distillation conditions, it is difficult to maintain the stability of the carbon material prepared by it. Based on the analysis of the physical and chemical properties of coal tar, it is known that its structure is mainly composed of polycyclic and condensed aromatic hydrocarbons and their derivatives, and it is generally highly hydrophobic. If hydrophilic functional groups are introduced into its molecular structure, surfactants with high added value and wide application range can be obtained.

[0003] Coal-water slurry is a high-concentration coal-water suspension that can be directly burned or used as a raw material for coal gasification. It has the advantages of low pollution, high efficiency and pipeline transportation, and is considered to be one of the important components of clean coal technology. Coal-water slurry is mainly composed of coal particles, water and additives, among which additives play an important role in the performance of the slurry. Among the additives, surfactants account for the main component. Surfactants are amphiphilic substances that can improve the surface properties and interface structure of coal by adsorption, increase the electrostatic repulsion and steric hindrance between coal particles, prevent coal particles from aggregating and adsorbing water, thereby reducing the viscosity of coal-water slurry and making it have good dispersibility and stability. The molecular structure of coal tar is very similar to the surface of coal. There is a strong π-π interaction and hydrophobic interaction between the two, which provides a necessary prerequisite for improving the surface structure of coal. However, at present, only the preparation of sulfonated coal tar by sulfonation has been reported. Such surfactants are difficult to effectively improve the steric hindrance between coal particles, resulting in poor stability of the slurry.

[0004] Therefore, in order to broaden the utilization of coal tar and improve the performance of coal tar-based surfactants in water-coal slurry, it is necessary to develop a new type of coal tar-based surfactant with steric hindrance effect, thereby improving the application performance of water-coal slurry. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a coal tar pitch-based surfactant and a preparation method and application thereof, so as to solve the technical problem that the existing sulfonated coal tar pitch has weak steric hindrance during pulping, resulting in poor slurry stability.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a method for preparing a coal tar pitch-based surfactant, comprising the following steps: S1: dissolving coal tar pitch in a first organic solvent, filtering, and drying to obtain an intermediate product I; adding the intermediate product I to a second organic solvent, adding chlorosulfonic acid under N2 protection and mixing evenly, heating and stirring to react, slowly adding phosphorus oxychloride, continuing to stir to react, cooling, filtering, washing, and drying to obtain an intermediate product II; S2: Dissolve the intermediate product II in the first portion of the second organic solvent, mix evenly, and obtain a solution containing the intermediate product II; dissolve the hydrophilic monomer in the second portion of the second organic solvent, mix evenly, and obtain a solution containing the hydrophilic monomer; add the solution containing the hydrophilic monomer to the solution containing the intermediate product II, stir evenly, heat and continue stirring to react, and then cool, filter, wash and dry to obtain a coal tar-based surfactant.

[0007] Preferably, in step S1, the general structural formula of coal tar pitch is: .

[0008] Preferably, in step S1, the coal tar pitch is any one of high-temperature coal tar pitch, medium-temperature coal tar pitch and low-temperature coal tar pitch; the first organic solvent is any one of benzene, toluene and quinoline; and the mass ratio of coal tar pitch to the first organic solvent is 1:(2-3.5).

[0009] Preferably, in step S1, the second organic solvent is any one of dichloromethane, chloroform and carbon tetrachloride; the mass ratio of intermediate product I: second organic solvent: chlorosulfonic acid: phosphorus oxychloride is 1: (2-3.5): (0.2-0.5): (0.1-0.3).

[0010] Preferably, in step S1, the conditions for the temperature-raising and stirring reaction are: stirring at 0-5°C for 1-2 hours; and continuing the stirring reaction for 2-4 hours.

[0011] Preferably, in step S2, the hydrophilic monomer is any one of polyethylene glycol 200, polyethylene glycol 400 and polyethylene glycol 600; the mass ratio of intermediate product II: second organic solvent: hydrophilic monomer is 1: (4-5): (0.9-1.1); the second organic solvent includes a first portion of the second organic solvent and a second portion of the second organic solvent, wherein the mass ratio of the first portion of the second organic solvent: the second portion of the second organic solvent is 1: (1-1.5).

[0012] Preferably, in step S2, the temperature is raised and the stirring reaction is continued at 60-80° C. for 6-12 hours.

[0013] The invention also discloses a coal tar pitch-based surfactant, which is prepared by the above preparation method.

[0014] Preferably, the general structural formula of the coal tar pitch-based surfactant is: ; Where n is the degree of polymerization, and the value range of n is 4~15.

[0015] The present invention also discloses the use of the coal tar pitch-based surfactant prepared by the preparation method in the preparation of Shenhua coal-water slurry, and the water separation rate of Shenhua coal-water slurry is 1.59-1.76 wt%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a method for preparing a coal tar pitch-based surfactant. The method selects coal tar pitch as a raw material, firstly introduces a chlorosulfonic acid group on the benzene ring in the coal tar pitch molecular structure through a sulfonylation reaction, then generates a sulfonic acid ester through an esterification reaction between the chlorosulfonic acid group and the terminal hydroxyl group on the hydrophilic chain, introduces the hydrophilic chain to the edge of the coal tar pitch molecule, and gives it surface activity, thereby obtaining a coal tar pitch-based surfactant containing both a hydrophobic aromatic ring and a hydrophilic long chain. The coal tar pitch selected by the invention is a low-value product after coal tar distillation, and preparing it into a surfactant with a wide range of applications is conducive to improving its added value, improving the comprehensive utilization efficiency of coal resources, and alleviating the energy crisis. At the same time, the method can effectively overcome the product performance differences caused by the fact that the structure and composition of the coal tar pitch are affected by the properties of the raw coal and the coking process, the quality of the coal tar and the distillation conditions, and the reaction process is simple and easy to control, which is suitable for large-scale production.

[0017] The present invention also discloses a coal tar pitch-based surfactant prepared by the above-mentioned preparation method. By adopting a unique chemical modification method, not only the low-value coal tar pitch is successfully converted into a high-value-added surfactant product, which significantly improves the comprehensive utilization efficiency of coal resources, but also the surfactant exhibits excellent dispersion and stability performance in application, especially in the preparation process of water-coal slurry, it can effectively reduce the viscosity of the system, improve the dispersibility of coal particles and the stability of the slurry, and provide strong support for the efficient and clean utilization of coal. It has broad industrial application prospects and significant economic benefits.

[0018] The present invention also discloses the use of the coal tar pitch-based surfactant prepared by the above-mentioned preparation method in the preparation of water-coal slurry. The water separation rate of Shenhua coal water-coal slurry is 1.59-1.76 wt%, and it has excellent stability. The coal tar pitch-based surfactant is used in the preparation of water-coal slurry as a new type of dispersant. Its dispersion and stability mechanism lies in that the central polyaromatic ring structure of the coal tar pitch-based surfactant is highly similar to the surface structure of coal. The two have strong π-π interaction and hydrophobic effect, and the adsorption fastness is high. At the same time, the long hydrophilic chain grafted on the edge can effectively provide steric hindrance, form a physical barrier between adjacent coal particles, and effectively prevent coal particles from aggregating, so that the water-coal slurry has a lower viscosity, good dispersibility and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a reaction mechanism diagram for preparing the coal tar pitch-based surfactant disclosed in the present invention; Figure 2 This is an infrared spectrum of the coal tar-based surfactant prepared in Example 3 disclosed in the present invention; Figure 3 This is a graph showing the viscosity reduction effect of the coal tar-based surfactant prepared in Example 1 disclosed in the present invention and the traditional sodium lignin sulfonate and sodium naphthalene sulfonate formaldehyde polymer on Shenhua coal-water slurry. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0022] The present invention is further described in detail below in conjunction with the accompanying drawings: The present invention discloses a method for preparing a coal tar pitch-based surfactant, comprising the following steps: S1: Dissolve coal tar pitch in a first organic solvent, filter out insoluble matter and dry to obtain intermediate product I; add intermediate product I to a second organic solvent, add chlorosulfonic acid under N2 protection and mix evenly, raise the temperature to T1 and stir to react for 1-2 hours; maintain the temperature at T1, then slowly add phosphorus oxychloride, react for 2-4 hours, cool, filter, wash and dry to obtain intermediate product II.

[0023] S2: Dissolve the intermediate product II in the first portion of the second organic solvent, mix evenly, and obtain a solution containing the intermediate product II; dissolve the hydrophilic monomer in the second portion of the second organic solvent, mix evenly, and obtain a solution containing the hydrophilic monomer; add the solution containing the hydrophilic monomer to the solution containing the intermediate product II, stir for 1 hour, raise the temperature to T2, and continue stirring the reaction for 6 to 12 hours; after cooling, filtering, washing and drying, a coal tar-based surfactant is obtained.

[0024] As an optional scheme, in step S1, the coal tar pitch is one of high-temperature coal tar pitch, medium-temperature coal tar pitch, and low-temperature coal tar pitch; the first organic solvent is one of benzene, toluene, and quinoline; the mass ratio of coal tar pitch: first organic solvent is 1: (2-3.5); the second organic solvent is one of dichloromethane, chloroform, and carbon tetrachloride; the mass ratio of intermediate product I: second organic solvent: chlorosulfonic acid: phosphorus oxychloride is 1: (2-3.5): (0.2-0.5): (0.1-0.3); the reaction temperature T1 is 0-5°C; As an optional scheme, in step S2, the hydrophilic monomer is one of polyethylene glycol 200, polyethylene glycol 400, and polyethylene glycol 600; the mass ratio of the intermediate product II: the second organic solvent: the hydrophilic monomer is 1: (4~5): (0.9~1.1); the second organic solvent includes a first portion of the second organic solvent and a second portion of the second organic solvent, wherein the mass ratio of the first portion of the second organic solvent: the second portion of the second organic solvent is 1: (1~1.5); and the reaction temperature T2 is 60~80°C.

[0025] In step S1, the general structural formula of coal tar pitch is:

[0026] The general structural formula of the prepared coal tar pitch-based surfactant is: ; Where n is the degree of polymerization, and the value range of n is 4~15.

[0027] The present invention also discloses a coal tar pitch-based surfactant prepared by the above preparation method. The dual characteristics of hydrophobic aromatic rings and hydrophilic long chains are integrated to give it excellent surface activity, so that the traditional industrial waste of coal tar pitch can be revitalized, bringing new product options to the surfactant industry, and also injecting new vitality into the comprehensive utilization of coal resources and the development of circular economy.

[0028] The present invention also discloses the application of the coal tar-based surfactant prepared by the above-mentioned preparation method in the preparation of Shenhua coal-water slurry, and the water separation rate of Shenhua coal-water slurry is 1.59~1.76 wt%, with excellent stability. Its special molecular structure enables it to be closely adsorbed on the surface of coal particles, and the binding force with coal particles is enhanced through π-π action and hydrophobic action. At the same time, the long hydrophilic chain on the edge provides sufficient steric hindrance for the coal slurry, effectively preventing the aggregation and sedimentation of coal particles. Under the joint action of these characteristics, the viscosity of the coal slurry is significantly reduced, the fluidity and stability of the coal slurry are improved, the combustion of the coal-water slurry is more complete, the energy utilization efficiency is improved, and the environmental pollution is reduced, which opens up a new way for the clean and efficient use of coal.

[0029] As an optional solution, the coal tar-based surfactant prepared by the above preparation method is used in the preparation of Shenhua coal-water slurry. According to the specific coal quality characteristics of Shenhua coal, the dispersion and stability of the coal slurry can be accurately adjusted to ensure that the coal slurry maintains the best flow state and combustion efficiency during the combustion process. This not only improves the product quality of Shenhua coal-water slurry, but also provides a strong guarantee for its wide application in the fields of power, chemical industry, etc.

[0030] A coal tar pitch-based surfactant prepared according to the above method is described in detail below in conjunction with specific embodiments: Example 1 A method for preparing a coal tar pitch-based surfactant comprises the following steps: S1: Dissolve 10g of high-temperature coal tar in 20g of toluene, stir evenly, filter to remove insoluble matter, and dry at 80°C to obtain intermediate product I. Add 5g of intermediate product I to 10g of dichloromethane, add 2g of chlorosulfonic acid under nitrogen protection, mix evenly, heat to 5°C and stir to react for 2h. Maintain this temperature, slowly add 0.5g of phosphorus oxychloride, and continue to react for 3h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0031] S2: Dissolve 1g of intermediate product II in 2g of dichloromethane, mix well, and obtain a solution containing intermediate product II; dissolve 1.1g of polyethylene glycol 200 in 2.5g of dichloromethane, mix well, and obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1h. Heat to 70°C and continue stirring and reacting for 8h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain a coal tar-based surfactant.

[0032] Example 2 A method for preparing a coal tar pitch-based surfactant comprises the following steps: S1: Dissolve 10g of medium-temperature coal tar in 25g of benzene, stir evenly, filter to remove insoluble matter, and dry at 70°C to obtain intermediate product I. Add 5g of intermediate product I to 15g of chloroform, add 1g of chlorosulfonic acid under nitrogen protection, mix evenly, heat to 3°C and stir to react for 1.5h. Maintain the temperature at 3°C, slowly add 1g of phosphorus oxychloride, and continue to react for 4h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0033] S2: Dissolve 1.25g of intermediate product II in 3g of chloroform, mix well, and obtain a solution containing intermediate product II; dissolve 1.25g of polyethylene glycol 400 in 3.25g of chloroform, mix well, and obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1h. Heat to 75°C and continue stirring for 10h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain a coal tar-based surfactant.

[0034] Example 3 A method for preparing a coal tar pitch-based surfactant comprises the following steps: S1: Dissolve 10g of low-temperature coal tar in 35g of quinoline, stir evenly, filter to remove insoluble matter, and dry at 90°C to obtain intermediate product I. Add 5g of intermediate product I to 17.5g of carbon tetrachloride, add 1g of chlorosulfonic acid under nitrogen protection, mix evenly, heat to 0°C and stir to react for 1h. Maintain the temperature at 0°C, slowly add 1.5g of phosphorus oxychloride, and continue to react for 2h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0035] S2: Dissolve 1.5g of intermediate product II in 2.5g of carbon tetrachloride, mix well, and obtain a solution containing intermediate product II; dissolve 1.65g of polyethylene glycol 600 in 3.75g of carbon tetrachloride, mix well, and obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1h. Heat to 65°C and continue stirring for 6h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain a coal tar-based surfactant.

[0036] Example 4 A method for preparing a coal tar pitch-based surfactant comprises the following steps: S1: Dissolve 10g of high-temperature coal tar in 35g of toluene, stir evenly, filter to remove insoluble matter, and dry at 80°C to obtain intermediate product I. Add 5g of intermediate product I to 15g of dichloromethane, add 2.5g of chlorosulfonic acid under nitrogen protection, mix evenly, heat to 4°C and stir to react for 1.5h. Maintain the temperature at 4°C, slowly add 1.5g of phosphorus oxychloride, and continue to react for 3h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0037] S2: Dissolve 2g of intermediate product II in 5g of dichloromethane, mix well, and obtain a solution containing intermediate product II; dissolve 1.8g of polyethylene glycol 400 in 5g of dichloromethane, mix well, and obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1h. Heat to 70°C and continue stirring for 9h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain a coal tar-based surfactant.

[0038] Example 5 A method for preparing a coal tar pitch-based surfactant comprises the following steps: S1: Dissolve 10g of medium-temperature coal tar in 32g of benzene, stir evenly, filter to remove insoluble matter, and dry at 75°C to obtain intermediate product I. Add 5g of intermediate product I to 17.5g of chloroform, add 2g of chlorosulfonic acid under nitrogen protection, mix evenly, heat to 2°C and stir to react for 2h. Maintain the temperature at 2°C, slowly add 0.5g of phosphorus oxychloride, and continue to react for 4h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0039] S2: Dissolve 2.5g of intermediate product II in 4g of chloroform, mix well, and obtain a solution containing intermediate product II; dissolve 2.5g of polyethylene glycol 600 in 6g of dichloromethane, mix well, and obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1h. Heat to 80℃ and continue stirring and reacting for 12h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain a coal tar-based surfactant.

[0040] Example 6 A method for preparing a coal tar pitch-based surfactant comprises the following steps: S1: Dissolve 10g of low-temperature coal tar in 30g of quinoline, stir evenly, filter to remove insoluble matter, and dry at 85°C to obtain intermediate product I. Add 5g of intermediate product I to 15g of carbon tetrachloride, add 2.5g of chlorosulfonic acid under nitrogen protection, mix evenly, heat to 5°C and stir to react for 1.5h. Maintain the temperature at 5°C, slowly add 1g of phosphorus oxychloride, and continue to react for 3h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0041] S2: Dissolve 3g of intermediate product II in 6g of carbon tetrachloride, mix well, and obtain a solution containing intermediate product II; dissolve 3g of polyethylene glycol 200 in 6g of carbon tetrachloride, mix well, and obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1h. Heat to 60°C and continue stirring for 6h. After the reaction is completed, cool to room temperature, filter, wash and dry to obtain a coal tar-based surfactant.

[0042] See also Figure 1 The diagram is a reaction mechanism diagram for the preparation of the coal tar pitch-based surfactant disclosed in the present invention; as can be seen from the diagram, with coal tar pitch as the raw material, after impurities are removed, a chlorosulfonic acid group is introduced into the benzene ring in the molecular structure of the coal tar pitch through a sulfonylation reaction of chlorosulfonic acid and phosphorus oxychloride, and then a sulfonate is generated through an esterification reaction between the chlorosulfonic acid group and the terminal hydroxyl group on the hydrophilic chain, and the hydrophilic chain is introduced into the edge of the coal tar pitch molecular structure to impart surface activity, thereby obtaining a coal tar pitch-based surfactant containing both a hydrophobic aromatic ring and a hydrophilic long chain.

[0043] Performance Characterization Taking Example 3 as an example, the coal tar pitch-based surfactant prepared in this example was characterized by infrared spectroscopy. The results are as follows: Figure 2 As shown. Figure 2It can be seen that the absorption peak at 3300 cm⁻¹ is attributed to the stretching vibration of the -OH bond, and the absorption peak at 3100 cm⁻¹ is derived from the stretching vibration of the CH bond on the benzene ring; at 2927 cm⁻¹ and 2819 cm⁻¹, the stretching vibration absorption peaks of the CH bond appear respectively; the absorption peak at 1725 cm⁻¹ is due to the stretching vibration of the -C=O bond; the absorption peak at 1330 cm⁻¹ is generated by the stretching vibration of -SO3; the absorption peak at 1550 cm⁻¹ is the bending vibration absorption of the CH bond; the absorption peak at 1031 cm⁻¹ comes from the stretching vibration of the S=O bond and the CO bond respectively. According to the infrared spectrum characteristics, it can be inferred that the hydrophilic chain has been successfully introduced into the edge of the molecular structure of coal tar pitch, and the coal tar pitch-based surfactant has been successfully synthesized.

[0044] In order to characterize the dispersing effect of coal tar-based surfactant on Shenhua coal-water slurry, the surfactant prepared in Example 1 was compared with traditional sodium lignin sulfonate and sodium naphthalene sulfonate formaldehyde polymer. The slurry concentration was fixed at 50 wt %, the dispersant dosage was 0.3 wt %, and the results of the slurry apparent viscosity changing with shear rate were shown in Figure 2. Figure 3 shown.

[0045] See also Figure 3 The graph is a graph showing the viscosity reduction effect of the coal tar-based surfactant prepared in Example 1 of the present invention and the traditional sodium lignin sulfonate and sodium naphthalene sulfonate formaldehyde polymer on Shenhua coal-water slurry; Figure 3 It can be seen that, with sodium lignin sulfonate and naphthalenesulfonic acid formaldehyde condensate as comparison, when the surfactant prepared in Example 1 is used, the apparent viscosity of the water-coal slurry first decreases and then tends to be flat as the shear rate increases, showing pseudoplastic fluid characteristics. -1 When the apparent viscosity of the Shenhua coal water slurry prepared in Example 1 dropped to 441 mPa·s, which was significantly lower than that of the Shenhua coal water slurry prepared by sodium lignin sulfonate. The water slurry prepared by naphthalenesulfonic acid formaldehyde condensate had poor stability and too fast coal particle sedimentation rate, resulting in hard precipitation at the bottom of the container during the measurement process, resulting in irregular changes in apparent viscosity.

[0046] In order to characterize the stabilizing effect of the coal tar-based surfactant of the present invention on the coal-water slurry of Shenhua coal, the coal-water slurries prepared in the above examples were stirred uniformly and poured into a 100 mL measuring cylinder (3 cm in diameter), and then the measuring cylinder was sealed and placed at room temperature for 3 days. The upper clear liquid of the slurry in the measuring cylinder was sucked out by a syringe and weighed, which was recorded as m 1. The mass of the supernatant and the total mass of the slurry ( m 0) is the water separation rate. The water separation rate is calculated using the following formula: Water separation rate (wt%) = m 1 / m 0×100%.

[0047] Table 1 Comparison of water separation rates of coal tar pitch based surfactants prepared in comparative examples and examples Surfactants Water separation rate of Shenhua coal-water slurry (wt%) Example 1 1.59 Example 2 1.76 Example 3 1.71 Example 4 1.63 Example 5 1.68 Example 6 1.70 Sodium lignin sulfonate 3.48 Naphthalenesulfonic acid formaldehyde condensate 6.63 It can be seen from Table 1 that the surfactant prepared in the embodiment of the present invention has a significantly lower water separation rate for Shenhua coal water slurry than that prepared by the other two surfactants (sodium lignin sulfonate and naphthalenesulfonic acid formaldehyde condensate), and has excellent stability.

[0048] The invention discloses a coal tar pitch-based surfactant and its preparation method and application. With coal tar pitch as raw material, after impurities are removed, a chlorosulfonic acid group is introduced into the benzene ring in the molecular structure of coal tar pitch through a sulfonylation reaction of chlorosulfonic acid and phosphorus oxychloride, and then a sulfonate is generated through an esterification reaction between the chlorosulfonic acid group and the terminal hydroxyl group on the hydrophilic chain, and the hydrophilic chain is introduced into the edge of the molecular structure of coal tar pitch, which is endowed with surface activity, thereby obtaining a coal tar pitch-based surfactant containing both a hydrophobic aromatic ring and a hydrophilic long chain. The central polyaromatic ring structure of the coal tar pitch-based surfactant of the invention is highly similar to the surface structure of Shenhua coal, and the two have strong π-π interaction and hydrophobic interaction, and have high adsorption fastness. At the same time, the long hydrophilic chain grafted on the edge can effectively provide steric hindrance, form a physical barrier between adjacent coal particles, effectively prevent coal particles from aggregating, and make the water-coal slurry have lower viscosity, good dispersibility and stability. The coal tar pitch selected by the invention is a low-value product after coal tar distillation, and preparing it into a surfactant with a wide range of applications is conducive to improving its added value. At the same time, the reaction process of the method is simple and easy to control, and is suitable for large-scale production.

[0049] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a coal tar pitch-based surfactant, characterized in that: The following steps are involved: S1: dissolving coal tar pitch in a first organic solvent, filtering, and drying to obtain an intermediate product I; The intermediate product I is added to the second organic solvent, and chlorosulfonic acid is added under N2 protection to mix evenly, and phosphorus oxychloride is slowly added after heating and stirring to react, and the stirring reaction is continued, and the intermediate product II is obtained after cooling, filtering, washing and drying. S2: Dissolve the intermediate product II in the first portion of the second organic solvent, mix evenly, and obtain a solution containing the intermediate product II; dissolve the hydrophilic monomer in the second portion of the second organic solvent, mix evenly, and obtain a solution containing the hydrophilic monomer; add the solution containing the hydrophilic monomer to the solution containing the intermediate product II, stir evenly, heat and continue stirring to react, and then cool, filter, wash and dry to obtain a coal tar-based surfactant.

2. The method for preparing the coal tar pitch-based surfactant according to claim 1, characterized in that: In step S1, the general structural formula of coal tar pitch is: 。 3. The method for preparing the coal tar pitch-based surfactant according to claim 1, characterized in that: In step S1, the coal tar pitch is any one of high-temperature coal tar pitch, medium-temperature coal tar pitch and low-temperature coal tar pitch; the first organic solvent is any one of benzene, toluene and quinoline; and the mass ratio of the coal tar pitch to the first organic solvent is 1:(2-3.5).

4. The method for preparing the coal tar pitch-based surfactant according to claim 1, characterized in that: In step S1, the second organic solvent is any one of dichloromethane, chloroform and carbon tetrachloride; the mass ratio of the intermediate product I: the second organic solvent: chlorosulfonic acid: phosphorus oxychloride is 1: (2-3.5): (0.2-0.5): (0.1-0.3).

5. The method for preparing the coal tar pitch-based surfactant according to claim 1, characterized in that: In step S1, the conditions for the temperature-raising and stirring reaction are: stirring at 0-5°C for 1-2 hours; and the stirring reaction time is continued for 2-4 hours.

6. The method for preparing the coal tar pitch-based surfactant according to claim 1, characterized in that: In step S2, the hydrophilic monomer is any one of polyethylene glycol 200, polyethylene glycol 400 and polyethylene glycol 600; the mass ratio of the intermediate product II: the second organic solvent: the hydrophilic monomer is 1: (4-5): (0.9-1.1); the second organic solvent includes a first portion of the second organic solvent and a second portion of the second organic solvent, wherein the mass ratio of the first portion of the second organic solvent: the second portion of the second organic solvent is 1: (1-1.5).

7. The method for preparing the coal tar pitch-based surfactant according to claim 1, characterized in that: In step S2, the temperature is raised and the stirring reaction is continued at 60-80° C. for 6-12 hours.

8. A coal tar pitch-based surfactant, characterized in that: The method is prepared by any one of claims 1 to 8.

9. The coal tar pitch-based surfactant according to claim 8, characterized in that: The general structural formula of the coal tar pitch-based surfactant is: ； Where n is the degree of polymerization, and the value range of n is 4~15.

10. Use of the coal tar pitch-based surfactant prepared by the preparation method according to any one of claims 1 to 8 in the preparation of Shenhua coal-water slurry, characterized in that: The water separation rate of the Shenhua coal-water slurry is 1.59-1.76 wt%.

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