JPH10245215A - Production of active carbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain active carbon which is an inexpensive industrial absorber and useful for anti-pollution without requiring high temperatures and high techniques in manufacturing using a cheap and stably available coal-based material as a raw material by heat treating and activating weathered coal in the presence of an alkali. SOLUTION: Weathered coal as a raw material is degenerated coal generated by the influence of sunlight, rain water, wind and sand, etc., in the air for a long time by being exposed, etc., on the ground and containing a large quantity of fumic acid. Though the weathered coal can be supplied as a raw material by properly crushing and, if needed, drying, it is preferable to use after treating with a dilute alkali solution such as an aqueous solution of sodium hydroxide, etc., to extract and remove a part of contained fumic acid. To the weathered coal, 0.1-10 pts.wt., preferably 1-5 pts.wt. of preferably an alkali metal hydroxide is added. Carbonization and activation is carried out at the same time in a carbonization oven by adding a predetermined amount of aqueous alkali solution and agitating the mixture, then, distilling water off and heating at preferably 400-650 deg.C for 1-5 hours.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing activated carbon.

[0002]

2. Description of the Related Art Activated carbon has long been used as an industrial adsorbent, but in recent years, its demand has been remarkably increased along with the development of technologies for preventing pollution. At present, activated carbon actually sold on the market is manufactured using palm, sawdust, coal and the like as raw materials, and is roughly classified into two types depending on the activation method: steam activated carbon and zinc chloride activated carbon.

[0003]

With respect to the above two types of activated carbon, the former requires a high temperature of 900 to 1200 ° C. in production, and the latter has a problem of corrosion and contamination by chemicals. All of them require a high level of technology during manufacture, and are pointed out as being problematic in that they are quite expensive. It has also been pointed out that there is concern about the supply of palm charcoal, which is currently one of the mainstreams, due to the import of raw material palm. On the other hand, when using coal as a raw material, in order to obtain desired properties by steam activation, it is common to use high-grade coal having high caking properties.

[0004]

The inventor of the present invention has conducted various studies in order to solve the above-mentioned problems by using a coal-based material which has low utility value as energy and can be supplied stably at low cost. Surprisingly, they have found that this object can be achieved by using weathered coal and by an alkali activation method, and have reached the present invention. That is, the gist of the present invention resides in a method for producing activated carbon, characterized in that the activated carbon is obtained by heat-treating weathered carbon in the presence of an alkali.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First, in the method of the present invention, weathered coal is used. Weathered coal is an altered coal containing a large amount of humic acid that is produced by the effects of long-term atmospheric exposure to sunlight, rain, water, snow, ice, wind and sand, etc. It is. Weathered coal has the following significant differences compared to raw coal. Chemical composition: High oxygen content (oxygen-containing group). Physical properties: Low mechanical strength and hardness, and excellent water absorption. Chemical properties: Regenerated corrosive acid has low calorific value and low ignition point. Process characteristics: low caking, low tar yield. Table 1 shows an example of analysis values of the original components of weathered coal and other coal.

[0006]

[Table 1] Table 1 ──────────────────────────────────── Industrial analysis (wt%) Humic acid ¹⁾ Elemental composition (wt%) ──────────── ───────────── Moisture Ash content Volatile component (wt%) CHON ───── ─────────────────────────────── Weathered coal 28.6 19.7-56.5 52.6 2.8 43.0 0.6 ───────── ─────────────────────────── Peat> 50-70 20 -40 50 -60 6 30 -40 1-3 Lignite 10- 50-45-55 10-35 60-75 5-6 10-30 1-3 Anthracite 1-8-10-50-75-90 4-5 2-10 1-3 Anthracite 1-2-<10- 90-95 3-4 1-2 1-3 ──────────────────────────────────── 1) Extraction method: 1N-NaOH, 24h

[0007] Weathered coal can be pulverized as appropriate and dried if necessary to provide the raw material of the present invention. However, it is preferable to use weathered coal obtained by removing at least a part of the humic acid contained by a conventional method. It is preferable from the viewpoint of improving the performance of the obtained activated carbon.
The removal of humic acid can be carried out by a conventional method, for example,
A method of extracting by treating with a dilute alkali solution such as an aqueous solution of caustic soda is employed.

[0008] Next, in the method of the present invention, an alkali is added to the above-mentioned weathered coal (including one in which humic acid is reduced). Examples of the alkali include hydroxides or carbonates of alkali metals such as sodium and potassium, calcium,
Examples thereof include hydroxides or carbonates of alkaline earth metals such as magnesium and barium. Of these, sodium hydroxide and potassium hydroxide are most suitable in view of the resulting high cost. These alkalis can be used both as solids and aqueous solutions.

The amount used is generally selected from about 0.1 to 10 parts by weight, preferably about 1 to 5 parts by weight, based on 1 part by weight of weathered coal. After the addition of the alkali, the weathered carbon is subjected to a heat treatment to obtain activated carbon. For example, after adding a predetermined amount of an aqueous alkali solution to weathered coal in a carbonization furnace and stirring well, heating is performed to distill off water, and the temperature is further increased to complete carbonization and activation at one time, and the contents are removed. Is taken out, water is added to collect the alkali, and the remaining carbide is sufficiently washed and dried to obtain high-performance activated carbon.

The above-mentioned heating is carried out at a temperature of about 300 to 900 ° C., preferably about 400 to 650 ° C., usually 0.5 to 48 ° C.
It is carried out for about an hour, preferably about 1 to 5 hours, and carbonization and activation are simultaneously performed. At the time of the heat treatment, a dry distillation furnace (firing furnace), for example, a rotary kiln can be used, and the temperature is raised at atmospheric pressure as it is or in a stream of an inert gas such as nitrogen. The water and cracked oil distilled off during the temperature rise are trapped and collected by a condenser attached to the outlet. Further, waste gas containing methane as a main component can be separately collected. Industrially, these by-products can be burnt and disposed.

After the above heat treatment is completed, after allowing to cool, the carbide containing alkali is taken out of the furnace and pulverized. First, water is added and washed by heating, and the alkali is recovered from the washing liquid. Further, the substrate is washed again by heating with dilute acid, and the pH of the washing solution becomes 7
It is preferable to repeat until it is before and after.

[0012]

The present invention will be described in more detail with reference to the following examples. Example 1 Weathered charcoal (humic acid 52%, ash content 25.5%) was mixed with sodium hydroxide (alkali ratio: alkali / weathered carbon = 2) and then put in a stainless steel beaker, which was placed in an iron retort. To a predetermined temperature in an electric furnace, heating rate 1 ° C
The heating was continued at / min, and after reaching 550 ° C, the temperature was maintained for 3 hours. During the heating, water was distilled off and gas generation was observed. The main component of the gas was methane. Then, let it cool down, wash the obtained charcoal with water,
The alkali was recovered to obtain activated carbon (yield: 51.2%). The iodine adsorption amount (JIS K1474) was 340 mg / g, and the specific surface area (BET method) was 446 m ² / g.

Example 2 The weathered raw material of Example 1 was first treated with 1N to reduce ash content.
-HCl solution, filtered, then insoluble components were stirred in 1N-NaOH solution, filtered, and humic acid reduced weathered charcoal (humic acid 40%,
(Ash content 26.5%). Activated carbon was produced in the same manner as in Example 1 (yield based on weathered raw material: 31.8).
%). Iodine adsorption amount 901mg / g, specific surface area 562m
² / g.

Claims (2)

[Claims] 1. A method for producing activated carbon, characterized in that weathered carbon is heat-treated in the presence of an alkali to obtain activated carbon. 2. A method for producing activated carbon, characterized in that weathered carbon from which at least a part of the contained humic acid has been removed is heat-treated in the presence of an alkali to obtain activated carbon.