阅读说明：本技术 一种通过烘焙预处理提高活性炭比表面积的加工工艺 (Processing technology for improving specific surface area of activated carbon through baking pretreatment ) 是由 马欢欢 周建斌 章一蒙 陈登宇 王恋 于 2020-07-06 设计创作，主要内容包括：本发明公开了一种通过烘焙预处理提高活性炭比表面积的加工工艺,包括以下步骤：1)预烘焙；2)预拌；3)活化；4)洗涤。本发明通过以酶解木质素为原料制备活性炭,实现酶解木质素的附加值利用,对木质素进行预烘焙,使其脱水缩合,无需添加化学助剂,实现木质素的聚合和酚类物质的产生,提高了木质素的聚合度,活化后制得的活性炭其比表面积明显提高,活性炭的得率增加,提高活性炭的品质,适合广泛推广与使用。(The invention discloses a processing technology for improving the specific surface area of activated carbon through baking pretreatment, which comprises the following steps: 1) pre-baking; 2) pre-mixing; 3) activating; 4) and (6) washing. According to the invention, the enzymatic hydrolysis lignin is used as the raw material to prepare the activated carbon, so that the additional value utilization of the enzymatic hydrolysis lignin is realized, the lignin is pre-baked to be subjected to dehydration condensation, no chemical additive is required to be added, the polymerization of the lignin and the generation of phenolic substances are realized, the polymerization degree of the lignin is improved, the specific surface area of the activated carbon prepared after activation is obviously improved, the yield of the activated carbon is increased, the quality of the activated carbon is improved, and the method is suitable for wide popularization and use.)

1. A processing technology for improving the specific surface area of activated carbon through baking pretreatment is characterized by comprising the following steps:

1) pre-baking;

2) pre-mixing;

3) activating;

4) and (6) washing.

2. The processing technology for improving the specific surface area of the activated carbon through the baking pretreatment as claimed in claim 1, is characterized by comprising the following steps:

1) pre-baking: putting lignin in a tube furnace, heating up, and preserving heat to obtain a product A;

2) pre-mixing: cooling the product A obtained in the last step to room temperature, dissolving an activating agent in pure water to prepare an activating agent solution, and uniformly mixing the activating agent solution with the product A to prepare a product B;

3) and (3) activation: drying the product B obtained in the previous step in an oven, transferring the product B to a tubular furnace, heating the product B by raising the temperature under the protection of inert gas, and preserving the temperature to obtain a product C;

4) washing: and cooling the product C obtained in the last step to room temperature, carrying out acid washing, then carrying out water washing, and finally drying in an oven to obtain the activated carbon.

3. The processing technology for improving the specific surface area of the activated carbon through the baking pretreatment as claimed in claim 2, wherein the step 1) comprises the following steps:

putting the lignin in a tube furnace, heating to 180-300 ℃ at a heating rate of 5-20 ℃/min, keeping the temperature for 30-120 min, and indirectly cooling and separating condensable liquid in gas generated by baking through water to obtain a product A.

4. The processing technology for improving the specific surface area of the activated carbon by the baking pretreatment as claimed in claim 2, is characterized in that: the mass ratio of the product A to the activating agent in the step 2) is (1:1) - (1: 4).

5. The processing technology for improving the specific surface area of the activated carbon through the baking pretreatment as claimed in claim 2, wherein the step 3) comprises the following steps:

and (3) placing the product B obtained in the last step in an oven, drying at the temperature of 100-110 ℃ for 4-6 h, transferring to a tubular furnace, heating to 885-915 ℃ at the heating rate of 2-10 ℃/min under the protection of nitrogen or other inert gases, and performing heat preservation and activation for 30-90 min to obtain a product C.

6. The processing technology for improving the specific surface area of the activated carbon through the baking pretreatment as claimed in claim 2, wherein the step 4) comprises the following steps:

and cooling the product C obtained in the last step to room temperature under the protection of nitrogen, washing with 3-8% hydrochloric acid for 4-6 times, washing with deionized water to neutrality, and finally drying in an oven at 100-110 ℃ for 3-5 hours to obtain the activated carbon.

7. The processing technology for improving the specific surface area of the activated carbon by the baking pretreatment as claimed in claim 3, wherein the processing technology comprises the following steps: the lignin in the step 1) is enzymatic hydrolysis lignin residue obtained by carrying out enzymatic hydrolysis on corn straws.

8. The processing technology for improving the specific surface area of the activated carbon by the baking pretreatment as claimed in claim 2, is characterized in that: the activating agent in the step 2) is one or two of potassium hydroxide and sodium hydroxide.

Technical Field

The invention relates to the field of activated carbon processing, in particular to a processing technology for improving the specific surface area of activated carbon through baking pretreatment.

Background

Activated carbon is a functional carbon material, has developed pores and strong adsorption capacity, is stable in physical and chemical properties, acid, alkali and heat resistant, and is widely applied to the fields of food and medicine, water treatment, gas purification, chemical environmental protection, energy storage materials, national defense safety and the like, coal, asphalt, biomass and the like are taken as raw materials for preparing the activated carbon through carbonization and activation in industry, along with the increase of the demand of various industries on the activated carbon, coal-based activated carbon has the problems that the production raw material source is not renewable, the environmental pollution is caused in production and the like, renewable and environment-friendly biomass raw materials are important substitutes, lignin is the second most abundant natural raw material in nature, the industrial lignin is generally derived from black liquor discharged in a large amount from a paper mill or residues for preparing bioethanol, more than 2000 million tons of industrial lignin are currently generated in China every year, but more than 98 percent of the industrial lignin is directly combusted, although there are some other applications, such as adhesives, plastic additives, etc., there has been no large-scale application so far, the lignin has a high carbon element content, and is a better raw material for preparing activated carbon, because lignin units are connected with each other through carbon-carbon bonds and ether bonds, and different connection modes among the units contain more terminal hydroxyl groups, methoxy groups and carbonyl groups, the bonds are easily broken and condensed by heating, and high-temperature carbonization and activation are needed during preparing activated carbon, while lignin is violently decomposed at about 330 ℃, so that the yield of the activated carbon after carbonization and activation is reduced, and the high specific surface area can improve the adsorption capacity of the activated carbon, therefore, we propose a processing technology for improving the specific surface area of the activated carbon through baking pretreatment.

Disclosure of Invention

The invention aims to provide a processing technology for improving the specific surface area of activated carbon through baking pretreatment, so as to solve the problems in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme: a processing technology for improving the specific surface area of activated carbon through baking pretreatment comprises the following steps:

1) pre-baking;

2) pre-mixing;

3) activating;

4) and (6) washing.

As a preferred embodiment of the present invention, the method comprises the following steps:

1) pre-baking: putting lignin in a tube furnace, heating up, and preserving heat to obtain a product A;

2) pre-mixing: cooling the product A obtained in the last step to room temperature, dissolving an activating agent in pure water to prepare an activating agent solution, and uniformly mixing the activating agent solution with the product A to prepare a product B;

3) and (3) activation: drying the product B obtained in the previous step in an oven, transferring the product B to a tubular furnace, heating the product B by raising the temperature under the protection of inert gas, and preserving the temperature to obtain a product C;

4) washing: and cooling the product C obtained in the last step to room temperature, carrying out acid washing, then carrying out water washing, and finally drying in an oven to obtain the activated carbon.

As a preferred embodiment of the present invention, the step 1) includes the steps of:

putting the lignin in a tube furnace, heating to 180-300 ℃ at a heating rate of 5-20 ℃/min, keeping the temperature for 30-120 min, and indirectly cooling and separating condensable liquid in gas generated by baking through water to obtain a product A.

In the technical scheme, through the step 1) of the pre-baking process, the lignin is subjected to dehydration condensation at a lower temperature, the polymerization degree of the lignin is improved, various phenolic substances in the lignin are removed, the specific surface area of the lignin is improved, the structure of the lignin is shaped, a chemical additive is not required to be added, the polymerization of enzymatic hydrolysis lignin and the volatilization of the phenolic substances are realized, the applicable temperature of the lignin dehydration condensation is 180-300 ℃, if the temperature is lower than the range, the lignin condensation degree is lower, even no condensation occurs, the expected effect of the pre-baking process cannot be realized, and if the temperature exceeds the range, the lignin is decomposed, and the yield of the activated carbon is reduced.

In a preferred embodiment of the present invention, the mass ratio of the product a to the activator in the step 2) is (1:1) to (1: 4).

In the technical scheme, in the step 2), the product obtained in the step 1) is mixed with an activating agent to act on functional groups in lignin, so that the flocculation and activation inhibiting effects of the functional groups on the lignin are eliminated, the subsequent activation reaction of the lignin is promoted, a basis is provided for improving the specific surface area and yield of the activated carbon, the activating agent and the product A are used according to the proportion, the activating agent can fully exert the effect, the activated carbon with high specific surface area is prepared in a short time, too much activating agent cannot promote the activation reaction, the preparation cost is increased, the equipment is corroded, and the subsequent treatment process is complicated.

As a preferred embodiment of the present invention, the step 3) includes the steps of:

and (3) placing the product B obtained in the last step in an oven, drying at the temperature of 100-110 ℃ for 4-6 h, transferring to a tubular furnace, heating to 885-915 ℃ at the heating rate of 2-10 ℃/min under the protection of nitrogen or other inert gases, and performing heat preservation and activation for 30-90 min to obtain a product C.

In the technical scheme, the lignin is activated in the nitrogen and high-temperature atmosphere in the step 3), pores blocked by disordered carbon atoms and other heteroatoms during condensation are opened and expanded, the activating agent promotes the activation reaction, volatile substances such as phenols in the lignin are removed in the step 1), the increase of the using amount of the activating agent is avoided, the pore structure of the activated carbon is formed, and the disordered carbon atoms and the other heteroatoms are reduced due to the fact that the polymerization degree of the lignin is improved in the step 1), the yield of the activated carbon is improved, and the effect of improving the specific surface area of the activated carbon is achieved.

As a preferred embodiment of the present invention, the step 4) includes the steps of:

and cooling the product C obtained in the last step to room temperature under the protection of nitrogen, washing with 3-8% hydrochloric acid for 4-6 times, washing with deionized water to neutrality, and finally drying in an oven at 100-110 ℃ for 3-5 hours to obtain the activated carbon.

In the technical scheme, the product obtained in the step 3) is cleaned in the step 4) to remove substances on the surface and in pores of the activated carbon, wherein the hydrochloric acid can clean and remove reaction residues of lignin in an activation process and adjust pH, the activation process of the lignin is stopped, the pores of the activated carbon are controlled, and deionized water is used for removing ions in the activated carbon to ensure the cleanness of the activated carbon.

As a preferred embodiment of the present invention, the lignin in step 1) is enzymatic hydrolysis lignin residue obtained by enzymatic hydrolysis of corn stalks.

In the technical scheme, the activated carbon is prepared by utilizing the enzymatic hydrolysis lignin, so that the additional value utilization of the enzymatic hydrolysis lignin is realized, the utilization rate of substances is improved, the resource saving is promoted, and the environment friendliness is realized.

As a preferred embodiment of the present invention, the activating agent in step 2) is one or both of potassium hydroxide and sodium hydroxide.

In the technical scheme, the activation process of the step 3) is combined, potassium hydroxide/sodium hydroxide reacts with disordered carbon atoms and other heteroatoms in lignin to generate potassium carbonate/sodium carbonate, pores are formed, potassium carbonate/sodium carbonate decomposes to generate potassium oxide/sodium oxide and carbon dioxide, micropore formation is promoted, potassium carbonate/sodium carbonate, potassium oxide/sodium oxide react with carbon atoms to generate metal potassium/sodium, the activation temperature in the activation process exceeds the boiling point of metal potassium/sodium, potassium/sodium steam diffuses to enter different carbon layers in lignin, lamella is enlarged to form a new micropore structure and influence the development of the pore structure, if the activation temperature is too high, carbon loss in lignin can be increased, the yield of activated carbon is reduced, and collapse of the micropore structure can be caused by increased carbon loss, the pore size distribution of the activated carbon is influenced, the pore size of the activated carbon is controlled, the specific surface area of the activated carbon is controlled, and the optimal adsorption performance of the activated carbon is achieved; and the polymerization degree of the lignin is improved due to the pre-baking process, and the reaction of potassium oxide/sodium oxide and potassium carbonate/sodium carbonate is reduced, so that the weight loss caused by the reaction is reduced, and the yield of the activated carbon is improved.

Compared with the prior art, the invention has the following beneficial effects:

according to the processing technology for improving the specific surface area of the activated carbon through the baking pretreatment, the activated carbon is prepared by taking the enzymatic hydrolysis lignin as a raw material, so that the additional value utilization of the enzymatic hydrolysis lignin is realized, the lignin is prebaked to be subjected to dehydration condensation, no chemical additive is required to be added, the polymerization of the lignin and the generation of phenolic substances are realized, the polymerization degree of the lignin is improved, the specific surface area of the activated carbon prepared after activation is obviously improved, the yield of the activated carbon is increased, and the quality of the activated carbon is improved.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.