Coal-tar pitch-based surfactant, its preparation method and application

Abstract

The application discloses a coal-tar pitch-based surfactant and a preparation method and application thereof, and belongs to the technical field of surfactants. The coal-tar pitch-based surfactant is prepared by the following steps: taking coal-tar pitch as raw material, removing impurities, introducing chlorosulfonic acid groups on benzene rings in the molecular structure of the coal-tar pitch through a sulfonylation reaction of chlorosulfonic acid and phosphorus oxychloride, and then introducing a hydrophilic chain to the edge of the molecular structure of the coal-tar pitch through an esterification reaction between the chlorosulfonic acid groups and terminal hydroxyl groups on the hydrophilic chain to endow the coal-tar pitch with surface activity, so that the coal-tar pitch-based surfactant containing both a hydrophobic aromatic ring and a hydrophilic long chain is obtained. The central polycyclic aromatic ring structure of the coal-tar pitch-based surfactant is highly similar to the surface structure of Shenhua coal, and the coal-tar pitch-based surfactant and the Shenhua coal have strong pi-pi interaction and hydrophobic interaction, high adsorption fastness, and a long hydrophilic chain grafted at the edge, which can effectively provide steric hindrance and form a physical barrier between adjacent coal particles to effectively prevent the coal particles from gathering, so that the coal water slurry has low viscosity, good dispersibility and stability.

Description

Technical Field

[0001] This invention belongs to the field of surfactant technology, specifically relating to a coal tar pitch-based surfactant, its preparation method, and its application. Background Technology

[0002] Coal tar pitch is the residue remaining after coal tar distillation, accounting for approximately 50% to 60% of the total coal tar production. With the development of the coking industry, a large amount of coal tar pitch is underutilized, severely impacting the comprehensive utilization efficiency of coal resources. Therefore, developing universally applicable and highly efficient coal tar pitch using new methods can not only effectively alleviate the energy crisis but also improve the overall economic and social benefits of the coal industry. Currently, coal tar pitch is mainly used to prepare electrodes, activated carbon, carbon fibers, needle coke, impregnating agents, and road construction materials. However, because the structure and composition of coal tar pitch vary depending on the properties of raw coal, coking process, coal tar quality, and distillation conditions, the performance of carbon materials prepared from it is difficult to maintain stability. Analysis of the physicochemical properties of coal tar pitch reveals that its structure is mainly composed of polycyclic aromatic hydrocarbons and their derivatives, exhibiting strong hydrophobicity overall. Introducing hydrophilic functional groups into its molecular structure can yield surfactants with high added value and a wide range of applications.

[0003] Coal-water slurry is a high-concentration coal-water suspension that can be directly burned or used as a feedstock for coal gasification. It boasts advantages such as low pollution, high efficiency, and pipeline transportability, and is considered a crucial component of clean coal technology. Coal-water slurry mainly consists of coal particles, water, and additives, with the additives playing a vital role in the slurry's properties. Surfactants are the primary component of the additives; as amphiphilic substances, they can improve the surface properties and interfacial structure of coal through adsorption, increasing the electrostatic repulsion and steric hindrance between coal particles, preventing coal particle aggregation and water adsorption, thereby reducing the viscosity of the coal-water slurry and giving it good dispersibility and stability. The molecular structure of coal tar pitch is very similar to that of the coal surface, and there are strong π-π interactions and hydrophobic interactions between them, providing a necessary prerequisite for improving the coal surface structure. However, currently, only sulfonated coal tar pitch has been reported to be prepared through sulfonation. Such surfactants are insufficient to effectively improve the steric hindrance between coal particles, resulting in poor slurry stability.

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

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a coal tar pitch-based surfactant, its preparation method and application, so as to solve the technical problem of poor slurry stability caused by weak steric hindrance during the preparation of sulfonated coal tar pitch.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for preparing a coal tar pitch-based surfactant, comprising the following steps:

[0008] S1: Coal tar pitch is dissolved in the first organic solvent, filtered, and dried to obtain intermediate product I; intermediate product I is added to the second organic solvent, and under N2 protection, chlorosulfonic acid is added and mixed evenly. After heating and stirring, phosphorus oxychloride is slowly added and the reaction is continued. After cooling, filtering, washing and drying, intermediate product II is obtained.

[0009] S2: Dissolve intermediate product II in the first part of the second organic solvent and mix evenly to obtain a solution containing intermediate product II; dissolve the hydrophilic monomer in the second part of the second organic solvent and mix evenly to obtain a solution containing the hydrophilic monomer; add the solution containing the hydrophilic monomer to the solution containing intermediate product II, stir evenly, heat and continue stirring reaction, and then cool, filter, wash and dry to obtain coal tar pitch-based surfactant.

[0010] Preferably, in step S1, the general structural formula of coal tar pitch is:

[0011] .

[0012] 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).

[0013] 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).

[0014] Preferably, in step S1, the conditions for heating and stirring the reaction are: stirring at 0~5℃ for 1~2 hours; and continuing to stir the reaction for 2~4 hours.

[0015] 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 part of second organic solvent and a second part of second organic solvent, wherein the mass ratio of the first part of second organic solvent: the second part of second organic solvent is 1:(1~1.5).

[0016] Preferably, in step S2, the conditions for heating and continuing the stirring reaction are 60~80℃ for 6~12h.

[0017] The present invention also discloses a coal tar pitch-based surfactant, which is prepared by the above-described preparation method.

[0018] Preferably, the general structural formula of the coal tar pitch-based surfactant is:

[0019] ;

[0020] Where n is the degree of aggregation, and the value of n ranges from 4 to 15.

[0021] The present invention also discloses the application of the coal tar pitch-based surfactant prepared by the above preparation method in the preparation of Shenhua coal-water slurry, wherein the water separation rate of Shenhua coal-water slurry is 1.59~1.76 wt%.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention discloses a method for preparing a coal tar pitch-based surfactant. The method uses coal tar pitch as a raw material. First, a chlorosulfonic acid group is introduced onto the benzene ring in the coal tar pitch molecule through a sulfonation reaction. Then, an esterification reaction is performed between the chlorosulfonic acid group and the hydroxyl group at the end of the hydrophilic chain to generate a sulfonate ester, introducing the hydrophilic chain to the edge of the coal tar pitch molecule and endowing it with surface activity. This yields a coal tar pitch-based surfactant containing both a hydrophobic aromatic ring and a hydrophilic long chain. The coal tar pitch used in this invention is a low-value product after coal tar distillation. Preparing it into a surfactant with a wide range of applications is beneficial for increasing its added value, improving the comprehensive utilization efficiency of coal resources, and alleviating the energy crisis. Simultaneously, this method can effectively overcome the product performance differences caused by the influence of the raw coal properties, coking process, coal tar quality, and distillation conditions on the structure and composition of coal tar pitch. The reaction process is simple and easy to control, making it suitable for large-scale production.

[0024] This invention also discloses a coal tar pitch-based surfactant prepared by the above-mentioned method. Using a unique chemical modification method, it not only successfully transforms low-value coal tar pitch into a high-value-added surfactant product, significantly improving the comprehensive utilization efficiency of coal resources, but also exhibits excellent dispersion stability in applications. In particular, during the preparation of coal-water slurry, it can effectively reduce the viscosity of the system, improve the dispersibility of coal particles and the stability of the slurry, providing strong support for the efficient and clean utilization of coal, and has broad industrial application prospects and significant economic benefits.

[0025] This invention also discloses the application of the coal tar pitch-based surfactant prepared by the above method in the preparation of coal-water slurry. The Shenhua coal-water slurry exhibits a water separation rate of 1.59~1.76 wt% and excellent stability. This coal tar pitch-based surfactant is used as a novel dispersant in the preparation of coal-water slurry. Its dispersion and stabilization mechanism lies in the fact that the central polyaromatic ring structure of the coal tar pitch-based surfactant is highly similar to the coal surface structure. Both exhibit strong π-π interactions and hydrophobic interactions, resulting in high adsorption strength. Simultaneously, the long hydrophilic chains grafted at the edges effectively provide steric hindrance, forming a physical barrier between adjacent coal particles, effectively preventing coal particle aggregation. This results in a coal-water slurry with low viscosity, good dispersibility, and stability. Attached Figure Description

[0026] Figure 1 This is a diagram illustrating the reaction mechanism for the preparation of the coal tar pitch-based surfactant disclosed in this invention.

[0027] Figure 2 The infrared spectrum of the coal tar pitch-based surfactant prepared in Example 3 of this invention;

[0028] Figure 3 The graph shows the viscosity-reducing effect of the coal tar pitch-based surfactant prepared in Example 1 of this invention on Shenhua coal-water slurry, compared with traditional sodium lignin sulfonate and sodium naphthalene sulfonate formaldehyde polymer. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] The present invention will now be described in further detail with reference to the accompanying drawings:

[0032] This invention discloses a method for preparing a coal tar pitch-based surfactant, comprising the following steps:

[0033] S1: Dissolve coal tar pitch in the first organic solvent, filter to remove insoluble matter, and dry to obtain intermediate product I; add intermediate product I to the second organic solvent, add chlorosulfonic acid under N2 protection, mix well, raise to temperature T1 and stir for 1-2 hours; keep the temperature at T1, then slowly add phosphorus oxychloride and react for 2-4 hours. After cooling, filtering, washing and drying, obtain intermediate product II.

[0034] S2: Dissolve intermediate product II in the first part of the second organic solvent and mix well to obtain a solution containing intermediate product II; dissolve the hydrophilic monomer in the second part of the second organic solvent and mix well to obtain a solution containing the hydrophilic monomer; add the solution containing the hydrophilic monomer to the solution containing intermediate product II, stir for 1 hour, raise the temperature to T2 and continue stirring for 6~12 hours; after cooling, filtering, washing and drying, obtain coal tar pitch-based surfactant.

[0035] As an optional option, in step S1, the coal tar pitch is one of high-temperature coal tar pitch, medium-temperature coal tar pitch, or low-temperature coal tar pitch; the first organic solvent is one of benzene, toluene, or quinoline; the mass ratio of coal tar pitch to the first organic solvent is 1:(2~3.5); the second organic solvent is one of dichloromethane, chloroform, or 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℃;

[0036] As an optional embodiment, in step S2, the hydrophilic monomer is 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 part of second organic solvent and a second part of second organic solvent, wherein the mass ratio of the first part of second organic solvent to the second part of second organic solvent is 1:(1~1.5); the reaction temperature T2 is 60~80℃.

[0037] In step S1, the general structural formula of coal tar pitch is:

[0038]

[0039] The general structural formula of the prepared coal tar pitch-based surfactant is:

[0040] ;

[0041] Where n is the degree of aggregation, and the value of n ranges from 4 to 15.

[0042] This invention also discloses a coal tar pitch-based surfactant prepared by the above-described method. Integrating the dual properties of a hydrophobic aromatic ring and a hydrophilic long chain, it possesses excellent surface activity, revitalizing coal tar pitch, a traditional industrial waste, and bringing new product options to the surfactant industry. It also injects new vitality into the comprehensive utilization of coal resources and the development of a circular economy.

[0043] This invention also discloses the application of the coal tar pitch-based surfactant prepared by the above method in the preparation of Shenhua coal-water slurry. The Shenhua coal-water slurry has a water separation rate of 1.59~1.76 wt% and exhibits excellent stability. Its unique molecular structure allows it to tightly adsorb onto the surface of coal particles, enhancing the binding force through π-π interactions and hydrophobic interactions. Simultaneously, the long hydrophilic chains at the edges provide sufficient steric hindrance for the slurry, effectively preventing coal particle aggregation and sedimentation. These combined properties significantly reduce the viscosity of the slurry, improve its fluidity and stability, resulting in more complete combustion of the coal-water slurry, improved energy utilization efficiency, reduced environmental pollution, and opening up new avenues for the clean and efficient utilization of coal.

[0044] As an alternative, the coal tar pitch-based surfactant prepared by the above method can be used in the preparation of Shenhua coal-water slurry. It can precisely adjust the dispersibility and stability of the coal slurry according to the specific coal quality characteristics of Shenhua coal, ensuring that the slurry maintains optimal flow and combustion efficiency during combustion. This not only improves the product quality of Shenhua coal-water slurry but also provides strong support for its widespread application in the power, chemical, and other fields.

[0045] A coal tar pitch-based surfactant prepared according to the above method is described in detail below with reference to specific embodiments:

[0046] Example 1

[0047] A method for preparing a coal tar pitch-based surfactant includes the following steps:

[0048] S1: Dissolve 10g of high-temperature coal tar pitch in 20g of toluene, stir until homogeneous, filter to remove insoluble matter, and dry at 80℃ to obtain intermediate product I. Add 5g of intermediate product I to 10g of dichloromethane, add 2g of chlorosulfonic acid under nitrogen protection, mix well, heat to 5℃ and stir for 2h. Maintain this temperature, slowly add 0.5g of phosphorus oxychloride, and continue the reaction for 3h. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0049] S2: Dissolve 1g of intermediate product II in 2g of dichloromethane and mix thoroughly to obtain a solution containing intermediate product II; dissolve 1.1g of polyethylene glycol 200 in 2.5g of dichloromethane and mix thoroughly to obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1 hour. Heat to 70℃ and continue stirring for 8 hours. After the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a coal tar pitch-based surfactant.

[0050] Example 2

[0051] A method for preparing a coal tar pitch-based surfactant includes the following steps:

[0052] S1: Dissolve 10g of medium-temperature coal tar pitch in 25g of benzene, stir until homogeneous, filter to remove insoluble matter, and dry at 70℃ to obtain intermediate product I. Add 5g of intermediate product I to 15g of chloroform, add 1g of chlorosulfonic acid under nitrogen protection, mix well, heat to 3℃ and stir for 1.5h. Maintain the temperature at 3℃, slowly add 1g of phosphorus oxychloride, and continue the reaction for 4h. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0053] S2: Dissolve 1.25g of intermediate product II in 3g of chloroform and mix thoroughly to obtain a solution containing intermediate product II; dissolve 1.25g of polyethylene glycol 400 in 3.25g of chloroform and mix thoroughly to obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1 hour. Heat to 75℃ and continue stirring for 10 hours. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain a coal tar pitch-based surfactant.

[0054] Example 3

[0055] A method for preparing a coal tar pitch-based surfactant includes the following steps:

[0056] S1: Dissolve 10g of low-temperature coal tar pitch in 35g of quinoline, stir well, filter to remove insoluble matter, and dry at 90℃ 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 well, heat to 0℃ and stir for 1h. Maintain the temperature at 0℃, slowly add 1.5g of phosphorus oxychloride, and continue the reaction for 2h. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0057] S2: Dissolve 1.5g of intermediate product II in 2.5g of carbon tetrachloride and mix thoroughly to obtain a solution containing intermediate product II; dissolve 1.65g of polyethylene glycol 600 in 3.75g of carbon tetrachloride and mix thoroughly to obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1 hour. Heat to 65℃ and continue stirring for 6 hours. After the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a coal tar pitch-based surfactant.

[0058] Example 4

[0059] A method for preparing a coal tar pitch-based surfactant includes the following steps:

[0060] S1: Dissolve 10g of high-temperature coal tar pitch in 35g of toluene, stir until homogeneous, filter to remove insoluble matter, and dry at 80℃ to obtain intermediate product I. Add 5g of intermediate product I to 15g of dichloromethane, and under nitrogen protection, add 2.5g of chlorosulfonic acid, mix well, heat to 4℃, and stir for 1.5h. Maintain the temperature at 4℃, slowly add 1.5g of phosphorus oxychloride, and continue the reaction for 3h. After the reaction is complete, cool to room temperature, filter, wash, and dry to obtain intermediate product II.

[0061] S2: Dissolve 2g of intermediate product II in 5g of dichloromethane and mix thoroughly to obtain a solution containing intermediate product II; dissolve 1.8g of polyethylene glycol 400 in 5g of dichloromethane and mix thoroughly to obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1 hour. Heat to 70℃ and continue stirring for 9 hours. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain a coal tar pitch-based surfactant.

[0062] Example 5

[0063] A method for preparing a coal tar pitch-based surfactant includes the following steps:

[0064] S1: Dissolve 10g of medium-temperature coal tar pitch in 32g of benzene, stir until homogeneous, filter to remove insoluble matter, and dry at 75℃ 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 well, heat to 2℃ and stir for 2h. Maintain the temperature at 2℃, slowly add 0.5g of phosphorus oxychloride, and continue the reaction for 4h. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0065] S2: Dissolve 2.5g of intermediate product II in 4g of chloroform and mix thoroughly to obtain a solution containing intermediate product II; dissolve 2.5g of polyethylene glycol 600 in 6g of dichloromethane and mix thoroughly to obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1 hour. Heat to 80℃ and continue stirring for 12 hours. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain a coal tar pitch-based surfactant.

[0066] Example 6

[0067] A method for preparing a coal tar pitch-based surfactant includes the following steps:

[0068] S1: Dissolve 10g of low-temperature coal tar pitch in 30g of quinoline, stir well, filter to remove insoluble matter, and dry at 85℃ 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 well, heat to 5℃ and stir for 1.5h. Maintain the temperature at 5℃, slowly add 1g of phosphorus oxychloride, and continue the reaction for 3h. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain intermediate product II.

[0069] S2: Dissolve 3g of intermediate product II in 6g of carbon tetrachloride and mix thoroughly to obtain a solution containing intermediate product II; dissolve 3g of polyethylene glycol 200 in 6g of carbon tetrachloride and mix thoroughly to obtain a solution containing hydrophilic monomers. Add the solution containing hydrophilic monomers to the solution containing intermediate product II and stir for 1 hour. Heat to 60℃ and continue stirring for 6 hours. After the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a coal tar pitch-based surfactant.

[0070] See Figure 1 This is a diagram illustrating the reaction mechanism for preparing the coal tar pitch-based surfactant disclosed in this invention. As can be seen from the diagram, coal tar pitch is used as a raw material. After impurity removal, chlorosulfonic acid groups are introduced onto the benzene ring in the coal tar pitch molecular structure through a sulfonation reaction of chlorosulfonic acid and phosphorus oxychloride. Then, sulfonate esters are generated through an esterification reaction between the chlorosulfonic acid groups and the hydroxyl groups at the upper end of the hydrophilic chain, introducing the hydrophilic chain to the edge of the coal tar pitch molecular structure and endowing it with surface activity, thus obtaining a coal tar pitch-based surfactant that simultaneously contains a hydrophobic aromatic ring and a hydrophilic long chain.

[0071] Performance Characterization

[0072] Taking Example 3 as an example, the coal tar pitch-based surfactant prepared in this example was characterized by infrared spectroscopy, and the results are as follows: Figure 2 As shown. From Figure 2 It can be seen that 3300 cm - The absorption peak at ¹ is attributed to the stretching vibration of the -OH bond, 3100 cm⁻¹ -The absorption peak at ¹ originates from the stretching vibration of the CH bond on the benzene ring; at 2927 cm⁻¹ - ¹ and 2819 cm - At position ¹, absorption peaks for the stretching vibrations of the CH bond appeared; at 1725 cm⁻¹ - The absorption peak at ¹ is due to the stretching vibration of the -C=O bond; 1330 cm⁻¹ - The absorption peak at ¹ is generated by the stretching vibration of -SO3; 1550 cm⁻¹ - The absorption peak at ¹ is due to the bending vibration absorption of the CH bond; 1031 cm⁻¹ - The absorption peaks at ¹ originate from the stretching vibrations of the S=O and CO bonds, respectively. Based on the infrared spectral characteristics, it can be inferred that the hydrophilic chain has been successfully introduced into the molecular structure edge of coal tar pitch, and the coal tar pitch-based surfactant has been successfully synthesized.

[0073] To characterize the dispersing effect of coal tar pitch-based surfactants on Shenhua coal-water slurry, the surfactant prepared in Example 1 was compared with traditional sodium lignosulfonate and sodium naphthalenesulfonate formaldehyde polymers. With the slurry concentration fixed at 50 wt% and the dispersant dosage at 0.3 wt%, the apparent viscosity of the slurry as a function of shear rate was as follows: Figure 3 As shown.

[0074] See Figure 3 The graph shows the viscosity-reducing effect of the coal tar pitch-based surfactant prepared in Example 1 of this invention, compared with traditional sodium lignin sulfonate and sodium naphthalene sulfonate formaldehyde polymers, on Shenhua coal-water-coal slurry. Figure 3 As can be seen, using sodium lignosulfonate and naphthalenesulfonic acid formaldehyde condensate as a comparison, when the surfactant prepared in Example 1 is used, the apparent viscosity of the coal-water slurry first decreases and then tends to level off with increasing shear rate, exhibiting pseudoplastic fluid characteristics. When the shear rate is 100 s⁻¹... -1 At that time, the apparent viscosity of the Shenhua coal-water slurry prepared in Example 1 decreased to 441 mPa·s, which was significantly lower than that of the Shenhua coal-water slurry prepared with sodium lignosulfonate. The coal-water slurry prepared with naphthalenesulfonic acid formaldehyde condensate had poor stability and an excessively fast coal particle settling rate, leading to hard sedimentation at the bottom of the container during the measurement process, resulting in irregular changes in apparent viscosity.

[0075] To characterize the stabilizing effect of the coal tar pitch-based surfactant of the present invention on Shenhua coal-water slurry, the coal-water slurry prepared in the above embodiments was stirred evenly and poured into a 100mL graduated cylinder (3cm in diameter). The cylinder was then sealed and left at room temperature for 3 days. The supernatant of the slurry in the graduated cylinder was aspirated using a syringe and weighed, and recorded as follows: m 1. The mass of the supernatant and the total mass of the slurry ( m 0) The ratio is the water separation rate. The water separation rate is calculated using the following formula: Water separation rate (wt%) =m 1 / m 0×100%.

[0076] Table 1. Comparison of water separation rates of coal tar pitch-based surfactants prepared in comparative examples and embodiments.

[0077]

[0078] As can be seen from Table 1, the surfactant prepared in the embodiments 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 lignosulfonate and naphthalenesulfonic acid formaldehyde condensate), and has excellent stability.

[0079] This invention discloses a coal tar pitch-based surfactant, its preparation method, and its application. Using coal tar pitch as raw material, after impurity removal, a chlorosulfonic acid group is introduced onto the benzene ring in the coal tar pitch molecular structure via a sulfonation reaction of chlorosulfonic acid and phosphorus oxychloride. Then, an esterification reaction between the chlorosulfonic acid group and the hydroxyl group at the upper end of the hydrophilic chain generates a sulfonate ester, introducing the hydrophilic chain to the edge of the coal tar pitch molecular structure, thus endowing it with surface activity. This yields a coal tar pitch-based surfactant containing both a hydrophobic aromatic ring and a long hydrophilic chain. The central polyaromatic ring structure of this invention's coal tar pitch-based surfactant is highly similar to the surface structure of Shenhua coal, exhibiting strong π-π interactions and hydrophobic interactions, resulting in high adsorption strength. Simultaneously, the long hydrophilic chains grafted at the edges effectively provide steric hindrance, forming a physical barrier between adjacent coal particles, effectively preventing coal particle aggregation, and resulting in low viscosity, good dispersibility, and stability of the coal-water slurry. The coal tar pitch used in this invention is a low-value product after coal tar distillation; preparing it into a surfactant with a wide range of applications is beneficial for increasing its added value. Furthermore, the reaction process of this method is simple and easy to control, suitable for large-scale production.

[0080] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a coal tar pitch-based surfactant, characterized in that, Includes the following steps: S1: Coal tar pitch is dissolved in a first organic solvent, filtered, and dried to obtain intermediate product I; Intermediate product I was added to a second organic solvent. Under N2 protection, chlorosulfonic acid was added and mixed evenly. After heating and stirring, phosphorus oxychloride was slowly added and the reaction was continued. After cooling, filtration, washing and drying, intermediate product II was obtained. S2: Dissolve intermediate product II in the first part of the second organic solvent and mix evenly to obtain a solution containing intermediate product II; dissolve the hydrophilic monomer in the second part of the second organic solvent and mix evenly to obtain a solution containing the hydrophilic monomer; add the solution containing the hydrophilic monomer to the solution containing intermediate product II, stir evenly, heat and continue stirring reaction, and then cool, filter, wash and dry to obtain coal tar pitch-based surfactant. 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). 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). 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 part of second organic solvent and a second part of second organic solvent, wherein the mass ratio of the first part of second organic solvent to the second part of second organic solvent is 1:(1~1.5).

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

3. The method for preparing the coal tar pitch-based surfactant according to claim 1, characterized in that, In step S2, the conditions for heating and continuing the stirring reaction are 60~80℃ for 6~12h.

4. A coal tar pitch-based surfactant, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 3.

5. The application of the coal tar pitch-based surfactant prepared by the preparation method according to any one of claims 1 to 3 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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