JPS623086B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing activated carbon, and more specifically, an industrially advantageous method for producing activated carbon with controlled pore distribution by selectively increasing the pore volume in a part or all of the transitional region. It is related to. Activated carbon is a carbon material with a developed porous structure, and has been widely used as an adsorbent or catalyst carrier in various fields such as chemical industry, food industry, water treatment, etc. However, the adsorption performance or carrier performance of activated carbon It largely depends on whether the characteristics such as specific surface area, pore volume, pore distribution, etc. match each application. For example, when activated carbon is used for wastewater treatment, conventional activated carbon has the disadvantage that relatively large molecular weight compounds cannot be removed, although this varies depending on the type of wastewater. The inventors of the present invention have conducted various studies on ways to solve these drawbacks, and as a result, we have found that the micro-region (diameter) of activated carbon
It has been found that it is most advantageous to use activated carbons that have an increased pore volume in part or all of the transitional zone (50-1000 Å in diameter) without changing the pore volume in the pore volume (less than 50 Å). On the other hand, the above-mentioned characteristics of activated carbon depend on the type of raw material,
Since it is inevitably determined by the carbonization atmosphere, the degree of activation, etc., it is extremely difficult to arbitrarily adjust only specific characteristics. For example, the pore volume is
It can be increased by increasing the activation degree, but even if the activation degree is increased, the pore volume in the entire region only increases, and it is not possible to selectively increase only the pore volume in the transitional region. Therefore, the present inventors have further investigated a method of selectively increasing only the pore volume in a part or all of the transitional region without changing other properties of activated carbon. It was discovered that almost satisfactory results could be obtained by performing gas activation after adding a certain amount of metal, and based on this knowledge, the present invention was completed. That is, in the present invention, when manufacturing activated carbon by activating a carbonaceous material by a gas activation method, in a step before the activation step, 0.001 to 1% by weight of metallic iron, nickel, or The present invention resides in a method for producing activated carbon, characterized in that one or more kinds of nickel metal salts are added. To explain the present invention in detail, carbonaceous materials used in the present invention include wood, sawdust, coconut shell, plant-based raw materials such as pulp waste liquid, phenolic resin, furan resin, urea resin, and polyvinyl chloride. Plastic raw materials such as resins and polycarbonates, coal such as lignite, lignite, bituminous coal, and anthracite, mineral raw materials such as petroleum residue, petroleum coke, and petroleum pitch are heated at temperatures below about 1000°C according to well-known methods. Powder or granules of about 0.3 to 6 mm that are carbonized at high temperatures are used as appropriate depending on the purpose. The metals added to these carbonaceous materials include:
Transition metals such as iron, cobalt, and nickel in various forms such as inorganic acid salts such as sulfates and nitrates, complex salts, and organic acid salts such as oxalates, or two or more of these. Used as a mixture. Note that the specification of Patent No. 79834 describes the use of zinc chloride as an additive metal, but if zinc chloride is used as an additive metal, it may cause corrosion of manufacturing equipment or waste gas, waste water, etc. generated from the manufacturing process. This is not preferred because it is difficult to process and furthermore, the zinc eluted during use of the product activated carbon has a negative effect on the objects to be treated. The metal salt may be added at any step before the activation step, for example, before or after carbonization, or before or after granulation or pulverization. The metal salt can be added by spraying a metal solution or suspension onto the carbonaceous material or its raw material, immersing the carbonaceous material or its raw material in the solution or suspension, or adding the metal salt to the carbonaceous material or its raw material. Examples include a method of mixing fine powder with a carbonaceous material or its raw material, but in any method, it is important to carry out the method so that the added metal salt is uniformly dispersed. Although the amount of metal salt added varies depending on the type of metal salt, the pore volume of the transitional region can be increased as the amount added is increased. However, if the amount added is too large, the pore volume in the micro region decreases, resulting in a decrease in surface area and product hardness. Also,
If the amount added is too small, the desired effect cannot be obtained, so it is usually added to carbonaceous materials as a single metal.
It is carried out within the range of 0.001 to 1% by weight, preferably 0.001 to 0.5% by weight. The carbonaceous material impregnated with or added with a metal salt is dried if necessary, and then heated with water vapor, carbon dioxide, air, It is activated to become activated carbon by contacting it with combustion gas, etc. As detailed above, the present invention selects the pore volume of part or all of the transitional region of activated carbon by a simple operation of adding a specific amount of metal salt to a carbonaceous material and then activating gas. Since the pore size can be increased and the pore distribution can be controlled, it is particularly useful as a method for producing activated carbon for wastewater treatment. In particular, when the activated carbon of the present invention is used in the decolorization process of refined sugar or the decolorization process of sodium L-glutamate solution, the activated carbon with a larger pore volume in the transitional region has higher decolorization performance. For example, a sodium L-glutamate solution obtained by neutralizing with sodium hydroxide L-glutamic acid separated from the fermentation liquid and containing impurities such as pigments such as molasses, melanoidin pigments, or a mixture of caramel, etc. In this case, the larger the pore volume of the activated carbon in the transitional region, the more the above-mentioned dye having a larger molecular weight contained in the solution is adsorbed and removed, resulting in better decolorizing performance. Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Example 1 First, 31 parts of a 10% cobalt nitrate aqueous solution was sprayed onto 100 parts of US coal granules crushed into particles with a particle size range of 0.84 to 2.38 mm and an average particle size of 1.4 mm. (Analysis of these granules revealed that 0.9% by weight of cobalt nitrate was attached as a metal.) Next, the granules were heated to 650°C using an externally heated rotary kiln and held at that temperature for 30 minutes to cause carbonization. I went. 60g of this carbonized coal was charged into a 70mmφ, 300mmL rotary kiln, and nitrogen gas was heated at 1.5N/min.
Steam activation was carried out at 950° C. under a flow of heated gas of 1.2 N/min of H ₂ O until the activation yield reached 40%. Packing density, average particle size, hardness, and
Iodine adsorption amount (IA), grain method molasses decolorization index (G-
ML), micro-region (diameter 50 Å or less), and transitional region (diameter 50-1000 Å) were measured. The measurement results are shown in Table 1. For comparison, Table 1 shows the physical properties of activated carbon obtained by treating the American charcoal granules used in Example 1 in exactly the same manner as in Example 1, except that the aqueous cobalt nitrate solution was not sprayed. Also listed. Example 2 The amount of sprayed 10% cobalt nitrate aqueous solution was set to 3.1 parts (the cobalt nitrate analysis value of the granules was
It was 0.08% by weight. ) Activated carbon was obtained by the same operation as in Example 1 except for the following. The physical properties of the obtained activated carbon were measured and the results are shown in Table 1. Example 3 Activated carbon was obtained in exactly the same manner as in Example 1, except that 3.1 parts of a 1% cobalt nitrate aqueous solution was sprayed instead of spraying the 10% cobalt nitrate aqueous solution. The physical properties of the obtained activated carbon were measured and the results are shown in Table 1. Example 4 The American coal granules used in Example 1 were carbonized under the same conditions as in Example 1. 10% Fe ₂ (SO ₄ ) ₃ aqueous solution 3.6 to 100 parts of this carbonized coal
(The Fe ₂ (SO ₄ ) ₃ analysis value of the carbonized coal was 0.1% by weight as metallic iron.), and then activated under the same conditions as in Example 1. The physical properties of the obtained activated carbon were measured and the results are shown in Table 1. Example 5 The carbonized carbon used in Example 5 was immersed in a 10% nickel acetate aqueous solution for 1 hour and then dried at 100°C.
(0.1% by weight). This dry carbonized charcoal was used in Example 1.
Activation treatment was performed under the same conditions. The physical properties of the obtained activated carbon were measured and the results are shown in Table 1. Example 6 20 wt% Fe ₂ (SO ₄ ) ₃ aqueous solution 10 parts to 100 parts of US coal granules
The same procedure as in Example 1 was carried out, except that the Fe ₂ (SO ₄ ) ₃ analysis value of the granules was 0.5% by weight as metallic iron. The physical properties of the obtained activated carbon were measured and the results are shown in Table 1. Comparative example 20wt% Fe ₂ (SO ₄ ) ₃ aqueous solution 37 to 100 parts of US coal granules
The same procedure as in Example 1 was carried out, except that the Fe ₂ (SO ₄ ) ₃ analysis value of the granules was 1.5% by weight as metallic iron. The physical properties of the obtained activated carbon were measured and the results are shown in Table 1.

【table】

[Table] Reference Example The decolorizing performance of a sodium L-glutamate solution was investigated using the activated carbon of the present invention. The activated carbon used was one prepared in the same manner as in Example 1 to have a pore volume of 50 to 300 Å as shown in Table 2.

【table】

Claims (1)

[Claims] 1. When manufacturing activated carbon by activating a carbonaceous material by a gas activation method, one type of metal salt of iron, cobalt, or nickel is added in a step before the activation step to the carbonaceous material in an amount of 0.001 to 1% by weight as a metal. Or a method for producing activated carbon, characterized by adding two or more kinds.