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CN-122010111-A - Method for preparing efficient adsorption active carbon by composite activator chemical method

CN122010111ACN 122010111 ACN122010111 ACN 122010111ACN-122010111-A

Abstract

The invention relates to the technical field of adsorption active carbon, in particular to a method for preparing high-efficiency adsorption active carbon by a compound activator chemical method, comprises the steps of directional modification pretreatment of raw materials, preparation of a composite activating agent, negative pressure auxiliary dipping treatment, sectional gradient activation and doping, graded composite post-treatment, drying forming and post-treatment. The preparation method comprises the steps of removing impurities, deashing, modifying and drying raw materials, dispersing an activating agent by multicomponent mixed liquid and adding nano particles, carrying out negative pressure impregnation on the raw materials and the activating agent, then freezing and thawing, carrying out gradient heating activation and synchronous doping on an aeration body, washing, oxidizing and modifying the activating material by an auxiliary agent, and finally drying, grading, modifying and granulating to obtain the high-efficiency adsorption activated carbon. The method improves the adsorption performance, mechanical strength and stability of the activated carbon through the cooperative optimization of the whole process, has less impurity residue and good repeatability, combines the environmental protection and industrialization suitability, has better comprehensive performance than the product of the traditional method, and adapts to the high-requirement adsorption scene.

Inventors

  • HUANG YUMING
  • Su Xuehai
  • YANG HUI

Assignees

  • 蜂窝活性炭有限公司

Dates

Publication Date
20260512
Application Date
20260114

Claims (10)

  1. 1. A method for preparing high-efficiency adsorption active carbon by a compound activator chemical method is characterized by comprising the following steps: S1, raw material directional modification pretreatment, namely crushing coconut shells or walnut shell raw materials, adding dilute hydrochloric acid with the mass concentration of 1.5-2.5mol/L, mixing according to the solid-liquid mass volume ratio of 1:8-12 (g/mL), stirring in a water bath to delicately remove ash, filtering, and washing deionized water to be neutral; S2, preparing a multi-effect ternary composite activator, namely mixing zinc chloride, dipotassium hydrogen phosphate and citric acid according to the mass ratio of 8-10:1-2:0.5-1, adding deionized water to prepare a mixed solution with the molar concentration of 5-7mol/L, adding concentrated hydrochloric acid with the volume fraction of 1-2%, adding nano silicon dioxide particles, stirring until the mixture is completely dissolved, and performing ultrasonic dispersion to obtain the ternary composite activator; s3, negative pressure auxiliary dipping treatment, namely adding the pretreatment raw materials and a ternary composite activating agent into a negative pressure dipping tank according to a solid-liquid mass volume ratio of 1:6-9 (g/mL), vacuumizing to-0.08 to-0.09 MPa, keeping for 10-15min, recovering normal pressure, then dipping in a constant temperature shaking box, supplementing and vacuumizing for 5min every 4h, and filtering to remove the redundant activating agent to obtain a dipping material which is uniformly dipped; S4, sectional gradient activation and in-situ doping, namely placing the impregnating compound in a nitrogen atmosphere tube furnace, heating to 350-400 ℃ for low-temperature activation for 0.5-1h, activating for 1-1.5h at a medium temperature of 500-550 ℃ and introducing ammonia gas for nitrogen doping, heating to 600-650 ℃ for high-temperature activation for 0.5-1h, and cooling to room temperature along with the furnace after activation to obtain a nitrogen doped activating compound; S5, carrying out graded compound aftertreatment, namely adding 0.2-0.3mol/L dilute hydrochloric acid into the activated material, stirring and washing in a water bath for 20-30min, filtering, washing in an ethanol solution for 10-15min, washing in deionized water until neutral, filtering to obtain a wet material, adding polyethylene glycol 400, stirring and mixing; s6, performing microwave vacuum collaborative drying molding, namely placing the wet material in a microwave vacuum drying oven, vacuumizing to-0.06 to-0.07 MPa, drying at 80-90 ℃ for 30-40min, cooling to room temperature, and crushing to obtain the efficient adsorption activated carbon.
  2. 2. The method for preparing the efficient adsorption active carbon by using the composite activator chemical method according to claim 1, wherein the method is characterized in that after the raw materials are crushed in S1, metal impurities mixed in the raw materials are removed through a magnetic separation process, the magnetic separation magnetic field strength is 800-1200Gs, the particle size screening is carried out after the magnetic separation, the method further comprises a microwave pre-drying step after the ultrasonic modification is finished, the microwave pre-drying power is 100-150W, the time is 5-8min, and the raw materials are dried in an oven after the pre-drying.
  3. 3. The method for preparing the efficient adsorption active carbon by the composite activator chemical method according to claim 1, wherein the nano silicon dioxide particles in the S2 are subjected to surface modification treatment by a silane coupling agent KH570 before being added, the nano silicon dioxide particles and KH570 ethanol solution with the mass concentration of 2-3wt% are mixed according to the solid-to-liquid ratio of 1g to 20mL, the mixture is stirred and modified for 1-1.5h at 50-60 ℃, the mixture is filtered and dried, and then the mixture is added into the composite activator solution, and the ultrasonic dispersion adopts a pulse ultrasonic mode with the pulse frequency of 2-3S/time.
  4. 4. The method for preparing high-efficiency adsorption active carbon by using the chemical method of composite activating agent as claimed in claim 1, wherein a rotary stirring paddle is arranged in the negative pressure impregnation tank in the step S3, the stirring paddle rotates at a low speed of 30-50r/min in the impregnation process, the impregnating material is subjected to freezing pretreatment after the negative pressure impregnation is finished, the freezing temperature is-10 to-15 ℃, the freezing time is 1-2h, and the impregnating material is naturally thawed to room temperature after being frozen and then enters the subsequent activation step.
  5. 5. The method for preparing the efficient adsorption active carbon by using the composite activator chemical method according to claim 1, wherein a multi-layer material bearing frame is arranged in the S4 tubular furnace, the impregnating material is uniformly spread on the bearing frame, the spreading thickness is 5-8mm, ammonia and nitrogen are introduced in a sectional mixing mode in a medium-temperature activation stage, the ammonia volume fraction is 5% in the first 30min, the ammonia volume fraction is gradually increased to 8% in the last 60min, and the introduction of ammonia is stopped in a high-temperature activation stage, and only nitrogen is introduced for protection.
  6. 6. The method for preparing high-efficiency adsorption active carbon by using the compound activator chemical method according to claim 1, wherein the washing of the dilute hydrochloric acid in the S5 adopts a dynamic countercurrent washing mode, the flowing direction of a washing solution and an activating material is opposite, an ozone oxidation treatment step is added after the washing of an ethanol solution, the ozone concentration is 50-80mg/L, the oxidation treatment time is 10-15min, deionized water washing is carried out after the ozone oxidation, and the ultrasonic dispersion treatment is carried out after the polyethylene glycol 400 is mixed, wherein the ultrasonic power is 100-150W and the time is 3-5min.
  7. 7. The method for preparing the efficient adsorption active carbon by the composite activator chemical method according to claim 1, wherein inert gas is introduced to purge in the microwave vacuum drying process in the step S6, the purge gas is argon, the flow rate of the argon is 50-80mL/min, the active carbon is subjected to surface hydrophobic modification treatment after the drying is finished, the modifier is methyltrimethoxysilane ethanol solution with the mass concentration of 1-2wt%, the modification temperature is 60-70 ℃, the modification time is 30-40min, and the active carbon is filtered and dried after the modification.
  8. 8. The method for preparing high-efficiency adsorption active carbon by using the composite activator chemical method according to claim 1, wherein the silane coupling agent in S1 is silane coupling agent KH560 or KH570, the pH value of the ultrasonic modification medium is adjusted according to the type of the coupling agent, the pH value is adjusted to 4.0-5.0 when KH560 is used, and the pH value is adjusted to 5.0-6.0 when KH570 is used.
  9. 9. The method for preparing the efficient adsorption active carbon by using the compound activator chemical method according to claim 1, wherein the S4 segmented gradient activation and in-situ doping are that an impregnating material is placed in an argon atmosphere tube furnace, the impregnating material is heated to 350-400 ℃ and activated for 0.5-1h at a low temperature, ammonia and sulfur are introduced for 1-1.5h at a medium temperature of 500-550 ℃, hydrogen sulfide gas with volume fraction of 3-5% is introduced during sulfur doping, the activating material is heated to 600-650 ℃ and activated for 0.5-1h at a high temperature, and the temperature is reduced to room temperature along with the furnace after activation, so that the sulfur doped activating material is obtained.
  10. 10. The method for preparing efficient adsorption active carbon by using the composite activator chemical method according to any one of claims 1 to 9, wherein the prepared efficient adsorption active carbon is subjected to granulation molding treatment, a sodium carboxymethyl cellulose aqueous solution with the mass of 5 to 8 percent of the active carbon is added as a binder during granulation, the mass concentration of the sodium carboxymethyl cellulose aqueous solution is 3 to 5 weight percent, and the granules are dried for 2 to 3 hours at 80 to 90 ℃ after granulation, so that the active carbon granules with the particle size of 2 to 5mm are obtained.

Description

Method for preparing efficient adsorption active carbon by composite activator chemical method Technical Field The invention relates to the technical field of adsorption activated carbon, in particular to a method for preparing efficient adsorption activated carbon by a compound activator chemical method. Background The active carbon is used as an adsorption material with high specific surface area and developed pore structure, and has wide application in the fields of water treatment, gas purification, energy storage and the like, and the preparation method is mainly divided into a physical activation method and a chemical activation method. The physical activation method has the advantages of simple process and good environmental protection, but has the problems of high activation temperature, long time consumption, limited adsorption performance improvement and the like, and is difficult to meet the requirement of the high-end field on the high-efficiency adsorption material. The chemical activation method regulates and controls the pore structure through the chemical reaction of the activating agent and the raw materials, has the advantages of low activation temperature, high efficiency, sufficient pore development and the like, and becomes a mainstream technology for preparing the efficient adsorption active carbon. At present, a single or binary composite activator is mostly adopted in the chemical activation method, such as zinc chloride, phosphoric acid, potassium hydroxide and the like, and the single activator has the defects of uneven pore distribution, low mesoporous ratio and the like, and the binary composite activator can optimize the performance to a certain extent, but has the defects in the aspect of pore structure guidance and surface functional group regulation. Meanwhile, the existing technology is not fine enough for pretreatment of raw materials, ash and impurities in the raw materials are easy to remain to influence the adsorption performance of the activated carbon, the activation agent is not permeated uniformly in the impregnation process, so that the pore development is inconsistent, the activation stage is mostly constant temperature or simply gradient temperature rise, and the accurate regulation and control of the pore and the collaborative optimization of surface doping are difficult to realize. In addition, the existing preparation method has the problems of single post-treatment process, easy collapse of pore structure, poor circulation stability of active carbon and the like, and restricts the application of the method in high-end adsorption scenes. Along with the iteration of environment-friendly requirement upgrading and adsorption technology, the market has higher requirements on the performances of the activated carbon such as adsorption capacity, selectivity, cycle life and the like, and development of a preparation method capable of accurately regulating and controlling pore structures, optimizing surface functional groups and improving comprehensive adsorption performance is urgently needed, and the problems of low activation efficiency, unbalanced performance, poor process stability and the like in the prior art are solved through multi-loop collaborative innovation, so that the diversified requirements of different fields on high-efficiency adsorption of the activated carbon are met. Disclosure of Invention (One) solving the technical problems Aiming at the defects of the prior art, the invention provides a method for preparing high-efficiency adsorption active carbon by a compound activator chemical method. (II) technical scheme A method for preparing high-efficiency adsorption active carbon by a compound activator chemical method comprises the following steps: S1, raw material directional modification pretreatment, namely crushing coconut shells or walnut shell raw materials, adding dilute hydrochloric acid with the mass concentration of 1.5-2.5mol/L, mixing according to the solid-liquid mass volume ratio of 1:8-12 (g/mL), stirring in a water bath to delicately remove ash, filtering, and washing deionized water to be neutral; S2, preparing a multi-effect ternary composite activator, namely mixing zinc chloride, dipotassium hydrogen phosphate and citric acid according to the mass ratio of 8-10:1-2:0.5-1, adding deionized water to prepare a mixed solution with the molar concentration of 5-7mol/L, adding concentrated hydrochloric acid with the volume fraction of 1-2%, adding nano silicon dioxide particles, stirring until the mixture is completely dissolved, and performing ultrasonic dispersion to obtain the ternary composite activator; s3, negative pressure auxiliary dipping treatment, namely adding the pretreatment raw materials and a ternary composite activating agent into a negative pressure dipping tank according to a solid-liquid mass volume ratio of 1:6-9 (g/mL), vacuumizing to-0.08 to-0.09 MPa, keeping for 10-15min, recovering normal pressure, then dipping i