CN101397136A - Method for preparing high specific surface area granular activated carbon by physical activation process - Google Patents

Abstract

The invention provides a method for preparing grain active carbon with high specific surface area by a physical activation method, comprising the steps as follows: firstly, coconut shell is carbonized under high temperature; subsequently, the crushed and screened carbonization material is arranged in a microwave radiation device; by controlling activation temperature and adjusting activation time and activation gas flux, the raw material is activated so as to gain the grain active carbon product with the specific surface area more than 2200m<2>/g. The method utilizes high-temperature carbonization to improve the micro-pore structure of the carbonization material of the coconut shell, is beneficial for improving the orderly structure of the carbonization material of the coconut shell, reduces the burning of the carbon during the carbonization process and improves the yield of the active carbon product; the prepared active carbon is the grain active carbon, and the applicable range is improved.

Description

A method for preparing high specific surface area granular activated carbon by physical activation

1. Technical field

The invention relates to a method for preparing granular activated carbon with a high specific surface area by a physical activation method, and belongs to the technical field of material preparation.

2. Background technology

Activated carbon is a kind of porous carbon material, which has a wide range of applications in the fields of chemical industry, environmental protection, metallurgy, electronics and energy. In recent years, with the development of science and technology, the application field of activated carbon has continued to expand, and new and higher requirements have been put forward for the adsorption performance. Under the general requirements of "high adsorption, multi-function, high strength", special-purpose The demand for activated carbon is increasing. At present, activated carbon with high specific surface area is usually prepared by chemical activation method. KOH, NaOH and other activators are used to prepare activated carbon with high specific surface area above 2000m ² /g, so that it can be used in electrodes, hydrogen storage, and storage of electric double layer capacitors. Methane and other fields. However, this method is corrosive to the equipment, and the prepared activated carbon is mostly powdery and has no strength, which brings certain limitations to its application; at the same time, the product needs to be pickled and washed with water after activation, which brings waste water. and other secondary pollutants, causing environmental pollution. Although the physical activation method does not pollute the environment, it often takes a long time to make the specific surface area reach more than 2000m ² /g when preparing activated carbon with a high specific surface area, which results in a high specific surface area prepared by the physical method. Activated carbon requires high energy consumption and long time, and the yield of the obtained product is low, which reduces the utilization rate of raw materials and causes a substantial increase in its production cost.

In the patent No. 200510010670.2, a "method for producing activated carbon with high specific surface area" is disclosed, using tobacco rods as raw materials, KOH as activator, pickling, washing and drying after microwave radiation to obtain activated carbon products . Due to the addition of reagents such as chemicals, this method has strong corrosiveness to equipment on the one hand, and needs pickling and water washing of its products on the other hand, which brings secondary pollution.

In "Research on Preparation of Activated Carbon with High Specific Surface Area by Coconut Shell Charcoal" published by Su Wei and others in "Forest Products Chemistry and Industry" No. 2, 2006, water vapor and CO ₂ were used as co-activation gases to prepare activated carbon in stages. Activated carbon with a specific surface area greater than 2000m ² /g needs at least 10 hours or more, and the yield is lower than 19.4%. It can be seen from the literature that this method requires precise control of the ratio of the mixed gas (water vapor and CO ₂ ) at different stages during the preparation process, which brings certain difficulties to the preparation process. In the patent No. 200510010669.X, a method of "physically treating tobacco rod waste to make activated carbon" is disclosed. The tobacco rod is used as the raw material, and water vapor is used as the activation gas. Although the required time is relatively short, its The product can only meet the requirements of commonly used activated carbon products, far from the application requirements of electrodes, hydrogen storage, methane storage and other fields of electric double layer capacitors, and the yield is also low (less than 30%).

Compared with the above-mentioned technology, the activated gas used in the present invention is water vapor and CO ₂ gas, which overcomes the corrosion of equipment and the pollution of the environment by chemical activation; The yield of activated carbon products is high (greater than 40%), which is conducive to improving the utilization of raw material resources; microwave is used as a heating source, and the temperature control is realized by adjusting the microwave power, and the prepared activated carbon is granular, which improves the application range .

3. Contents of the invention

The object of the present invention is to provide a method for preparing granular activated carbon with a high specific surface area by a physical activation method. First, the coconut shell is carbonized at a high temperature, and then the carbonized material after crushing and sieving is placed in a microwave radiation device. Activation temperature, activation time and activation gas flow are adjusted, and raw materials are activated to obtain granular activated carbon products with a specific surface area of 2200m ² /g or more.

The present invention is realized through the following process steps, and Fig. 1 is its process flow chart.

(1) Coconut shells are carbonized at 800-1200°C for 1-3 hours in a carbonization furnace;

(2) crushing and sieving the carbonized coconut shell carbonized material, and getting a particle size of 4 to 30 mesh particles;

(3) The crushed coconut shell carbonized material is placed in a microwave radiation device, and when heated to 800-950 ° C, activated gas is passed through to activate, and a high specific surface area activated carbon product is obtained.

Among them, when water vapor is used as the activation gas, the flow rate is 0.5-4L/min.Kg (water vapor flow rate per kilogram of carbon per minute); when _CO2 is used as the activation gas, the flow rate is 1-5L/min.Kg (CO ₂ gas flow rate per kilogram of charcoal per minute); when the mixed gas of CO ₂ and water vapor is used as the activation gas, the ratio of CO ₂ and water vapor is 5-1:1, and the flow rate is 0.5-6L/min. Kg (mixed gas flow per minute per kilogram of charcoal).

The present invention has the following advantages:

(1) One or mixed gas of water vapor and _CO2 is used as the activation gas, which does not produce three wastes, has no pollution to the environment, and has little corrosion to equipment;

(2) Using high-temperature carbonization to improve the microporous structure of coconut shell carbonized materials, it provides a raw material with a relatively developed pore structure for the preparation of activated carbon with high specific surface area; it is beneficial to improve the ordered structure of coconut shell carbonized materials and reduce carbon in the activation process. The ablation in the medium increases the yield of activated carbon products;

(3) Utilize the internal heating and selective heating characteristics of microwaves to overcome the temperature gradient inside the material, which is conducive to the diffusion of activated gas inside the material, speed up the reaction speed, shorten the activation time, achieve energy saving and consumption reduction, and benefit the active point Reaction with activated gas effectively promotes the formation of pores and improves the yield of activated carbon;

(4) The activated carbon prepared is granular activated carbon, which improves its scope of application;

4. Specific implementation

Example 1: Take 200g of coconut shell carbonized material after high-temperature carbonization, place it in a microwave radiation device, heat it to 900 ° C, feed water vapor, and its water vapor flow rate is 0.5L/min. After activating for 1.25 hours, a high specific surface area of activated carbon products. The yield is 42.2%, the iodine adsorption value is 1569.47mg/g, the specific surface area is 2279m ² /g, and the pore volume is 1.212cm ³ /g.

Example 2: Take 150 g of coconut shell carbonized material after high-temperature carbonization, place it in a microwave radiation device, heat it to 850 ° C, and feed CO ₂ , wherein the flow rate of CO ₂ is 0.6 L/min. After 3 hours of activation, a high specific surface area of activated carbon products. Its yield, iodine adsorption value, specific surface area and pore volume are 49.2%, 1456.37mg/g, 2203m ² /g and 1.255cm ³ /g respectively.

Embodiment 3: Get 250g of coconut shell carbonized material after high-temperature carbonization, place it in a microwave radiation device, heat to 900°C, feed water vapor and _CO Mixed gas, wherein the ratio of _CO and water vapor is 3:1, The flow rate of the mixed gas is 0.8L/min, and after 1 hour of activation, an activated carbon product with a high specific surface area is obtained. The yield is 50.6%, the iodine adsorption value is 1485.03mg/g, the specific surface area is 2250m ² /g, and the pore volume is 1.157cm ³ /g.

Claims (2)

1. a physical activation method prepares the method for high specific surface area granular activated carbon, it is characterized in that: realize as follows,

(1) with coconut husk in charring furnace 800～1200 ℃ of following charings 1～3 hour;

(2) the coconut husk carbonized material after the charing is carried out fragmentation, screening, getting particle diameter is 4～30 purpose particles;

(3) the coconut husk carbonized material after the fragmentation places microwave radiation device, when being heated to 800～950 ℃, feeding activated gas and activates, and obtains the high specific surface area granular activated carbon product.

2. physical activation method according to claim 1 prepares the method for high specific surface area granular activated carbon, it is characterized in that: described activated gas is water vapour and CO ₂A kind of in the gas, or both gas mixtures, when being activated gas with water vapour, its flow is 0.5～4L/min.Kg; With CO ₂During for activated gas, its flow is 1～5L/min.Kg; With CO ₂When being activated gas with the mixed gas of water vapour, CO ₂With the ratio of water vapour be 5～1: 1, its flow is 0.5～6L/min.Kg.