Process for treating asphaltic light components contained in waste n-methylpyrrolidone and activated carbon

Abstract

The application discloses a method for treating asphalt light components in waste N-methyl pyrrolidone and activated carbon, and the method comprises the following steps: (1) performing vacuum distillation on the waste N-methyl pyrrolidone so as to obtain a black viscous substrate; (2) mixing the black viscous substrate with concentrated sulfuric acid; (3) mixing the reaction residue obtained in the step (2) with water after cooling to room temperature, performing washing and filtering, and then performing drying so as to obtain solid particles; (4) mixing the solid particles with potassium hydroxide, and performing a corrosion pore-forming reaction under a nitrogen atmosphere so as to obtain an activated product; and (5) mixing the activated product with dilute hydrochloric acid, performing washing and filtering so as to obtain the activated carbon. By using the method, the N-methyl pyrrolidone can be efficiently recovered, and the asphalt light components can be converted into the activated carbon with high added value.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering, specifically relating to a method for treating light asphalt components in waste N-methylpyrrolidone and activated carbon. Background Technology

[0002] N-Methylpyrrolidone (NMP) is a good organic solvent with a high boiling point and low toxicity. It is an excellent solvent for extracting light components from asphalt. The purpose of extraction is to allow the light components in asphalt to enter the NMP, thereby enriching the heavy components in the asphalt. Heavy asphalt components can be further processed into many downstream products (such as high softening point asphalt, spinning asphalt, etc.). However, the extracted light asphalt components, without high-value-added conversion, have no significant value other than fuel, and there is an urgent need to develop deep processing technologies. Furthermore, NMP is relatively expensive, and the NMP used in extraction is a waste solution; if it is not separated from the light asphalt components and recycled, it will result in significant waste. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for treating light asphalt components in waste N-methylpyrrolidone and activated carbon. The method can not only achieve efficient recovery of N-methylpyrrolidone, but also convert light asphalt components into high-value activated carbon.

[0004] In one aspect of the present invention, a method for treating light asphalt components in waste N-methylpyrrolidone is provided. According to an embodiment of the present invention, the method includes: (1) distilling the waste N-methylpyrrolidone under reduced pressure to obtain a black viscous substrate; (2) mixing the black viscous substrate with concentrated sulfuric acid; (3) cooling the reaction product obtained in step (2) to room temperature, washing and filtering it with water, and then drying it to obtain solid particles; (4) mixing the solid particles with potassium hydroxide and performing a corrosion pore-forming reaction under a nitrogen atmosphere to obtain an activated product; (5) mixing the activated product with dilute hydrochloric acid, washing and filtering it to obtain activated carbon.

[0005] Preferably, in step (1), the distillation temperature is 135-140°C.

[0006] Preferably, in step (2), the black viscous substrate and the concentrated sulfuric acid are mixed at a mass ratio of (0.5-1):1.

[0007] Preferably, in step (2), the black viscous substrate is mixed with the concentrated sulfuric acid at a temperature of 35-80°C for 2-5 hours.

[0008] Preferably, in step (4), the ratio of the solid particles to the potassium hydroxide is 1:(1-3).

[0009] Preferably, in step (4), the temperature of the corrosion pore-forming reaction is 800-900℃, and the holding time is 1-2h.

[0010] Preferably, in step (5), the mass concentration of the dilute hydrochloric acid is 18-19%.

[0011] Preferably, in step (5), the mass ratio of the activated product to the dilute hydrochloric acid is 1:(100-150).

[0012] Preferably, in step (5), the activation product is mixed with the dilute hydrochloric acid at a temperature of 50-60°C for 3-3.5 hours.

[0013] In a second aspect, the present invention provides an activated carbon. According to an embodiment of the present invention, the activated carbon is prepared by the method described above.

[0014] Compared with existing technologies, the method for recovering light asphalt components from waste N-methylpyrrolidone of the present invention first involves vacuum distillation of the waste N-methylpyrrolidone to separate and recover the N-methylpyrrolidone from the system. The black, viscous substrate containing light asphalt components is then mixed with concentrated sulfuric acid to oxidize the light asphalt components. The resulting reaction mixture is then cooled to room temperature, washed, and filtered with water, followed by drying. The resulting solid particles are then mixed with potassium hydroxide and reacted under a nitrogen atmosphere. The corrosive nature of KOH allows the solid particles to form pores. Furthermore, because the solid particles have been oxidized by concentrated sulfuric acid, their oxygen-containing functional groups (mainly sulfonic acid groups, hydroxyl groups, carboxyl groups, etc.) have a strong affinity for KOH, thus enhancing the corrosion and pore-forming reaction. Finally, the resulting activated product is mixed with dilute hydrochloric acid, washed, and filtered to obtain activated carbon with a high specific surface area. Therefore, the method of the present invention not only achieves efficient recovery of N-methylpyrrolidone but also converts light asphalt components into high-value-added activated carbon. Detailed Implementation

[0015] The present invention will be further described below with reference to the embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0016] In one aspect of the invention, a method for treating light asphalt components in waste N-methylpyrrolidone is provided. According to an embodiment of the invention, the method includes:

[0017] S1: Vacuum distillation of waste N-methylpyrrolidone

[0018] In this step, the waste NMP solution containing light asphalt components is added to a vacuum distillation apparatus, heated to 135-140℃ and maintained for 0.5h, and vacuum is applied until the solution boils. The valve is adjusted to maintain a stable boiling state, and distillation is carried out for 2-2.5h. The collected distillate is the recovered NMP, which is pale yellow. The remaining substance after distillation is mainly composed of light asphalt components and is a black viscous substrate.

[0019] S2: Mix the black viscous substrate with concentrated sulfuric acid.

[0020] In this step, the obtained black viscous substrate is mixed with concentrated sulfuric acid (98 wt%). The oxidizing properties of the concentrated sulfuric acid oxidize the black viscous substrate, producing oxygen-containing functional groups such as sulfonic acid groups, hydroxyl groups, and carboxyl groups. These oxygen-containing functional groups have a strong affinity for KOH, thereby enhancing the subsequent high-temperature corrosion and pore-forming reaction. Further, the black viscous substrate and concentrated sulfuric acid are mixed at a mass ratio of (0.5-1):1, and the mixing temperature is controlled at 35-80°C for 2-5 hours. Maintaining the mixing temperature within this range enhances the oxidizing properties of the concentrated sulfuric acid, thereby improving the oxidation of the black viscous substrate.

[0021] S3: After cooling the reaction mixture obtained in step S2 to room temperature, mix it with water for washing and filtration.

[0022] In this step, the reaction product obtained in step S2 is cooled to room temperature and added to deionized water under stirring to dilute the excess concentrated sulfuric acid and prevent danger in subsequent operations. The amount of deionized water used is 10-20 times the mass of the reaction product. The system is then washed and filtered multiple times with deionized water until the pH value of the wash water between two adjacent washes does not change significantly. The system is then dried at 110-120℃ to obtain solid particles.

[0023] S4: Solid particles are mixed with potassium hydroxide and then subjected to a corrosion pore-forming reaction under a nitrogen atmosphere.

[0024] In this step, the solid particles obtained in step S3 are crushed, and the resulting solid powder is dissolved together with KOH in deionized water. The amount of KOH used is 1.0-3.0 times the mass of the solid powder, and the amount of deionized water used is the same as the amount of KOH. After the system is stirred evenly, it is treated at 110℃ for 12 hours to remove moisture. Then, under nitrogen protection, the temperature is increased to 800-900℃ at 5-7.5℃ / min and maintained for 1-2 hours to perform corrosion and pore formation. Afterward, it is allowed to cool naturally to room temperature to obtain the activated product. The inventors discovered that KOH is corrosive at high temperatures and reacts with the crushed solid powder. The main mechanism of the reaction is that the highly corrosive KOH reacts with the carbon atoms in the solid powder, causing partial elimination of carbon atoms in the powder structure, thereby creating pores. Furthermore, since the solid powder has been oxidized by concentrated sulfuric acid, its oxygen-containing functional groups (mainly sulfonic acid groups, hydroxyl groups, carboxyl groups, etc.) have a strong affinity for KOH, thus enhancing the corrosion and pore-forming reaction and increasing the specific surface area of ​​the activated product.

[0025] S5: After mixing the activated product with dilute hydrochloric acid, wash and filter.

[0026] In this step, the activated product obtained above is mixed with dilute hydrochloric acid (mass concentration of 18-19%) at a mass ratio of 1:(100-150), and stirred at 50-60℃ for 3-3.5h to remove excess KOH and carbonates produced during the high-temperature reaction. After filtration, the mixture is washed and filtered multiple times with deionized water to remove excess hydrochloric acid and chlorides (chlorides are products of the reaction of KOH, carbonates, etc. with hydrochloric acid). After washing and filtering until the washing water is neutral, the activated carbon product is dried to obtain the activated carbon product.

[0027] Therefore, the method of the present invention can not only achieve efficient recovery of N-methylpyrrolidone, but also convert light asphalt components into high-value-added activated carbon.

[0028] In a second aspect, the present invention provides an activated carbon. According to an embodiment of the present invention, the activated carbon is prepared by the method described above.

[0029] It should be noted that the features and advantages described above for the method of treating light asphalt components in waste N-methylpyrrolidone also apply to this activated carbon, and will not be repeated here.

[0030] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and should not be construed as limiting the present invention in any way.

[0031] Example 1

[0032] (1) Add the waste NMP solution containing light asphalt components to the vacuum distillation apparatus, heat to 135-140℃ and maintain for 0.5h, vacuum reduce the pressure until the solution boils, adjust the valve to maintain boiling stability, distill for 2.5h, the collected distillate is the recovered NMP, which is light yellow, and the remaining substance after distillation is mainly composed of light asphalt components, which is a black viscous substrate.

[0033] (2) The black viscous substrate in step (1) was mixed with concentrated sulfuric acid (98wt%) at a mass ratio of 1:1, and the temperature was controlled at 35℃ for 5 hours.

[0034] (3) Cool the reaction material in step (2) to room temperature and add it to deionized water under stirring to dilute the excess concentrated sulfuric acid and prevent danger in subsequent operations. The amount of deionized water is 20 times the mass of the reaction material obtained in step (2). The system is then washed with deionized water and filtered multiple times until the pH value of the washing water between two adjacent washes does not change significantly. The system is then dried at 120°C to obtain solid particles.

[0035] (4) Crush the solid particles in step (3) to pass through a 300-mesh sieve to obtain solid powder. Dissolve the solid powder together with KOH in deionized water. The amount of KOH is 2.0 times the mass of the solid powder, and the amount of deionized water is the same as the amount of KOH. After the system is stirred evenly, treat the system at 110°C for 12 hours to remove moisture.

[0036] (5) The mixture in step (4) is heated to 850°C at 7.5°C / min under nitrogen protection and held for 1.5h to perform corrosion and pore formation. After that, it is allowed to cool naturally to room temperature to obtain the activated product.

[0037] (6) The activated product from step (5) is mixed with 100 times its mass of dilute hydrochloric acid (mass concentration of 18-19%), and stirred at 50°C for 3 hours to remove excess KOH and carbonates produced during the high-temperature reaction. The mixture is then filtered, and subsequently washed and filtered multiple times with deionized water to remove excess hydrochloric acid and chlorides. After washing and filtering until the washing water is neutral, the activated carbon product is dried to obtain a specific surface area of ​​2380 m². 2 / g.

[0038] Example 2

[0039] (1) Add the waste NMP solution containing light asphalt components to a vacuum distillation apparatus, heat it to 135-140℃ and keep it for 0.5h, vacuum reduce the pressure until the solution boils, adjust the valve to maintain the boiling stability, distill for 2h, the collected distillate is the recovered NMP, which is light yellow, and the remaining substance after distillation is mainly composed of light asphalt components, which is a black viscous substrate.

[0040] (2) The black viscous substrate in step (1) was mixed with concentrated sulfuric acid (98wt%) at a mass ratio of 0.75:1, and the temperature was controlled at 60℃ for 3 hours.

[0041] (3) Cool the reaction material in step (2) to room temperature and add it to deionized water under stirring to dilute the excess concentrated sulfuric acid and prevent danger in subsequent operations. The amount of deionized water is 10 times the mass of the reaction material in step (2). The system is then washed and filtered with deionized water multiple times until the pH value of the washing water between two adjacent washes does not change significantly. The system is then dried at 110°C to obtain solid particles.

[0042] (4) Crush the solid particles in step (3) to pass through a 300-mesh sieve to obtain solid powder. Dissolve the solid powder together with KOH in deionized water. The amount of KOH is 3.0 times the mass of the solid powder, and the amount of deionized water is the same as the amount of KOH. After the system is stirred evenly, treat the system at 110°C for 12 hours to remove moisture.

[0043] (5) The mixture in step (4) is heated to 800°C at 5°C / min under nitrogen protection and held for 2 hours to form pores through corrosion. After that, it is allowed to cool naturally to room temperature to obtain the activated product.

[0044] (6) The activated product from step (5) is mixed with 150 times its mass of dilute hydrochloric acid (mass concentration of 18-19%), and stirred at 60°C for 3.5 h to remove excess KOH and carbonates produced during the high-temperature reaction. The mixture is then filtered, and subsequently washed and filtered multiple times with deionized water to remove excess hydrochloric acid and chlorides. After washing and filtering until the washing water is neutral, the activated carbon product is dried to obtain a specific surface area of ​​2706 m². 2 / g.

[0045] Example 3

[0046] (1) Add the waste NMP solution containing light asphalt components to a vacuum distillation apparatus, heat it to 135-140℃ and keep it for 0.5h, vacuum reduce the pressure until the solution boils, adjust the valve to maintain the boiling stability, distill for 2h, the collected distillate is the recovered NMP, which is light yellow, and the remaining substance after distillation is mainly composed of light asphalt components, which is a black viscous substrate.

[0047] (2) The black viscous substrate in step (1) was mixed with concentrated sulfuric acid (98wt%) at a mass ratio of 0.5:1, and the temperature was controlled at 80℃ for 2 hours.

[0048] (3) Cool the reaction material in step (2) to room temperature and add it to deionized water under stirring to dilute the excess concentrated sulfuric acid and prevent danger in subsequent operations. The amount of deionized water is 20 times the mass of the reaction material in step (2). The system is then washed and filtered with deionized water multiple times until the pH value of the washing water between two adjacent washes does not change significantly. The system is then dried at 120°C to obtain solid particles.

[0049] (4) Crush the solid particles in step (3) to pass through a 300-mesh sieve to obtain solid powder. Dissolve the solid powder together with KOH in deionized water. The amount of KOH is 3.0 times the mass of the solid powder, and the amount of deionized water is the same as the amount of KOH. After the system is stirred evenly, treat the system at 110°C for 12 hours to remove moisture.

[0050] (5) The mixture in step (4) is heated to 900°C at 5°C / min under nitrogen protection and held for 1 hour to perform corrosion and pore formation. After that, it is naturally cooled to room temperature to obtain the activated product.

[0051] (6) The activated product from step (5) is mixed with 150 times its mass of dilute hydrochloric acid (mass concentration of 18-19%), and stirred at 60°C for 3.5 h to remove excess KOH and carbonates produced during the high-temperature reaction. The mixture is then filtered, and subsequently washed and filtered multiple times with deionized water to remove excess hydrochloric acid and chlorides. After washing and filtering until the washing water is neutral, the activated carbon product is dried to obtain a specific surface area of ​​2966 m². 2 / g.

[0052] Example 4

[0053] (1) Add the waste NMP solution containing light asphalt components to the vacuum distillation apparatus, heat to 135-140℃ and maintain for 0.5h, vacuum reduce the pressure until the solution boils, adjust the valve to maintain boiling stability, distill for 2.5h, the collected distillate is the recovered NMP, which is light yellow, and the remaining substance after distillation is mainly composed of light asphalt components, which is a black viscous substrate.

[0054] (2) The black viscous substrate in step (1) was mixed with concentrated sulfuric acid (98wt%) at a mass ratio of 1:1, and the temperature was controlled at 45℃ for 4 hours.

[0055] (3) Cool the reaction material in step (2) to room temperature and add it to deionized water under stirring to dilute the excess concentrated sulfuric acid and prevent danger in subsequent operations. The amount of deionized water is 10 times the mass of the reaction material in step (2). The system is then washed and filtered with deionized water multiple times until the pH value of the washing water between two adjacent washes does not change significantly. The system is then dried at 110°C to obtain solid particles.

[0056] (4) Crush the solid particles in step (3) to pass through a 300-mesh sieve to obtain solid powder. Dissolve the solid powder together with KOH in deionized water. The amount of KOH is 1.5 times the mass of the solid powder, and the amount of deionized water is the same as the amount of KOH. After the system is stirred evenly, treat the system at 110°C for 12 hours to remove moisture.

[0057] (5) The mixture in step (4) is heated to 850°C at 7.5°C / min under nitrogen protection and held for 1.5h to perform corrosion and pore formation. After that, it is allowed to cool naturally to room temperature to obtain the activated product.

[0058] (6) The activated product from step (5) is mixed with 100 times its mass of dilute hydrochloric acid (mass concentration of 18-19%), and stirred at 50°C for 3 hours to remove excess KOH and carbonates produced during the high-temperature reaction. The mixture is then filtered, and subsequently washed and filtered repeatedly with deionized water to remove excess hydrochloric acid and chlorides. After washing and filtering until the washing water is neutral, the activated carbon product is dried to obtain a specific surface area of ​​1847 m². 2 / g.

[0059] Example 5

[0060] (1) Add the waste NMP solution containing light asphalt components to a vacuum distillation apparatus, heat it to 135-140℃ and keep it for 0.5h, vacuum reduce the pressure until the solution boils, adjust the valve to maintain the boiling stability, distill for 2h, the collected distillate is the recovered NMP, which is light yellow, and the remaining substance after distillation is mainly composed of light asphalt components, which is a black viscous substrate.

[0061] (2) The black viscous substrate in step (1) was mixed with concentrated sulfuric acid (98wt%) at a mass ratio of 0.8:1, and the temperature was controlled at 35℃ for 3h.

[0062] (3) Cool the reaction material in step (2) to room temperature and add it to deionized water under stirring to dilute the excess concentrated sulfuric acid and prevent danger in subsequent operations. The amount of deionized water is 10 times the mass of the reaction material in step (2). The system is then washed and filtered with deionized water multiple times until the pH value of the washing water between two adjacent washes does not change significantly. The system is then dried at 110°C to obtain solid particles.

[0063] (4) Crush the solid particles in step (3) to pass through a 300-mesh sieve to obtain solid powder. Dissolve the solid powder together with KOH in deionized water. The amount of KOH is 1.0 times the mass of the solid powder, and the amount of deionized water is the same as the amount of KOH. After the system is stirred evenly, treat the system at 110°C for 12 hours to remove moisture.

[0064] (5) The mixture in step (4) is heated to 800°C at 5°C / min under nitrogen protection and held for 2 hours to form pores through corrosion. After that, it is allowed to cool naturally to room temperature to obtain the activated product.

[0065] (6) The activated product from step (5) is mixed with 100 times its mass of dilute hydrochloric acid (mass concentration of 18-19%), and stirred at 50°C for 3 hours to remove excess KOH and carbonates produced during the high-temperature reaction. The mixture is then filtered, and subsequently washed and filtered multiple times with deionized water to remove excess hydrochloric acid and chlorides. After washing and filtering until the washing water is neutral, the activated carbon product is dried to obtain a specific surface area of ​​1540 m². 2 / g.

[0066] Comparative Example

[0067] (1) Add the waste NMP solution containing light asphalt components to a vacuum distillation apparatus, heat it to 135-140℃ and keep it for 0.5h, vacuum reduce the pressure until the solution boils, adjust the valve to maintain the boiling stability, distill for 2h, the collected distillate is the recovered NMP, which is light yellow, and the remaining substance after distillation is mainly composed of light asphalt components, which is a black viscous substrate.

[0068] (2) Mix the black viscous substrate from step (1) with KOH (since the substrate is not oxidized, it cannot be compatible with KOH in an aqueous system and cannot be mixed evenly, so direct stirring is used for mixing). The amount of KOH used is 1.0 times the mass of the solid powder.

[0069] (3) The mixture in step (2) is heated to 800°C at 5°C / min under nitrogen protection and held for 2 hours to perform corrosion and pore formation. After that, it is naturally cooled to room temperature to obtain the activated product.

[0070] (4) The activated product from step (3) is mixed with 100 times its mass of dilute hydrochloric acid (mass concentration of 18-19%), and stirred at 50°C for 3 hours to remove excess KOH and carbonates produced during the high-temperature reaction. The mixture is then filtered, and subsequently washed and filtered multiple times with deionized water to remove excess hydrochloric acid and chlorides. After washing and filtering until the washing water is neutral, the activated carbon product is dried to obtain a specific surface area of ​​1037 m². 2 / g.

[0071] The difference between the comparative example and Examples 1-5 is that, in the comparative example, the black viscous substrate was not mixed with concentrated sulfuric acid, but rather directly mixed with KOH. The results showed that the specific surface area of ​​the activated carbon product obtained in the comparative example was smaller than that of the product obtained in Example 5, indicating that oxidation with concentrated sulfuric acid can enhance the pore-forming effect at high temperatures, resulting in an activated carbon product with a higher specific surface area. Therefore, the method of this invention can not only achieve efficient recovery of N-methylpyrrolidone, but also convert light asphalt components into high-value-added activated carbon.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for treating asphaltic light components contained in waste N-methylpyrrolidone, characterized in that, The method comprises: (1) distilling waste N-methyl pyrrolidone under reduced pressure to obtain a black viscous substrate; (2) mixing the black viscous substrate with concentrated sulfuric acid; (3) cooling the post-reaction material obtained in step (2) to room temperature, mixing with water, washing and filtering, and then drying to obtain solid particles; (4) mixing the solid particles with potassium hydroxide and performing a corrosion pore-forming reaction under a nitrogen atmosphere to obtain an activated product; (5) mixing the activated product with dilute hydrochloric acid, washing and filtering to obtain activated carbon, In step (1), the waste N-methyl pyrrolidone contains asphalt light components, and the distillation temperature is 135-140℃.

2. The method of claim 1, wherein, In step (2), the black viscous substrate is mixed with the concentrated sulfuric acid at a mass ratio of (0.5-1):

1.

3. The method according to claim 1 or 2, characterized in that, In step (2), the mixing temperature of the black viscous substrate and the concentrated sulfuric acid is 35-80℃, and the time is 2-5h.

4. The method of claim 1, wherein, In step (4), the mass ratio of the solid particles to the potassium hydroxide is 1:(1-3).

5. The method according to claim 1 or 4, characterized in that, In step (4), the corrosion pore-forming reaction temperature is 800-900℃, and the holding time is 1-2h.

6. The method of claim 1, wherein, In step (5), the mass concentration of the dilute hydrochloric acid is 18-19%.

7. The method according to claim 1 or 6, characterized in that, In step (5), the mass ratio of the activated product to the dilute hydrochloric acid is 1:(100-150).

8. The method of claim 1 or 6, wherein, In step (5), the mixing temperature of the activated product and the dilute hydrochloric acid is 50-60℃, and the time is 3-3.5h.