JPS62729B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for removing malodorous components such as hydrogen sulfide and mercaptan from gas. Petroleum refining, petrochemical, pulp and paper, viscose rayon, food, pharmaceutical and other chemical factories, human waste treatment plants, sewage treatment plants, etc. contain sulfur compounds such as hydrogen sulfide, carbonyl sulfide, and mercaptans that give off bad odors. Generation of exhaust gas cannot be avoided. To remove these sulfur compounds,
Although various exhaust gas treatment methods using activated carbon and the like have been attempted, none of these methods can be said to be sufficient to remove sulfur compounds that give off a strong odor even at extremely low concentrations. In view of these circumstances, the present inventors conducted various studies and found that activated carbon raw materials include alkali metal carbonates, sulfates, phosphates, halides, acetates,
The activated carbon, which is obtained by carbonization and activation by adding oxalate, benzoate or phenol salts (hereinafter referred to as alkali metal salts), and which contains a specific amount of alkali metal, can very efficiently convert the sulfur compounds into gas. We found that it can be removed from The present invention is based on this new knowledge. That is, the present invention is an activated carbon that is obtained by adding an alkali metal salt to an activated carbon raw material and then carbonizing and activating the raw material, and containing an alkali metal of more than 2.0 mg-atoms and less than 5.0 mg-atoms per gram of activated carbon (hereinafter referred to as alkali metal salt). This is a method for removing malodors in a gas, which is characterized by contacting supported activated carbon with a gas containing at least one of hydrogen sulfide, carbonyl sulfide, mercaptans, and sulfides as a main malodor component. Examples of mercaptans as malodorous components to be removed in the method of the present invention include alkyl mercaptans such as methyl mercaptan, ethyl mercaptan, and propyl mercaptan, and aryl mercaptans such as phenyl mercaptan; examples of sulfides include methyl sulfide, Examples include alkylthioethers such as ethyl sulfide, and arylthioethers such as phenyl sulfide. The alkali metal-supported activated carbon in the present invention is obtained by adding an alkali metal salt to a raw material for producing ordinary activated carbon, followed by carbonization and activation. The raw materials include:
For example, carbohydrates, grains, coconut shells, sawdust,
Examples include vegetable substances such as wood, and mineral substances such as coal and petroleum coke. Examples of the alkali metal of the alkali metal salt to be added include Li,
Examples include Na, K, Rb, and Cs. The amount of alkali metal salt added to the raw material varies depending on the raw material used, but it is 2.0 to 5.0 in terms of alkali metal per gram of activated carbon obtained by carbonization and activation.
mg-atom. The alkali metal salt may be dissolved in water or a solvent, or added as a solid to the raw material. When added in the form of a solid, a method of mixing and pulverizing the raw material and the alkali metal salt is preferred. A preferred method is to add an alkali metal salt to the raw materials, then add water and/or a suitable binder, and then knead and shape the mixture. The raw material containing the alkali metal salt obtained in this way is carbonized and activated by a conventional method. The carbonization temperature is 400-850℃ and the activation temperature is 700-1100℃. Activation can be carried out in an air stream of O ₂ , CO ₂ , H ₂ O, combustion gas, or the like. One of the features of the present invention is that the activation rate by these gases is significantly increased by adding an alkali metal salt to the raw materials. The method of the present invention is carried out by bringing the alkali metal-supported activated carbon obtained above into contact with a gas containing a sulfur compound. The contact temperature in this case is 0 to 250°C, preferably 5 to 150°C.
The contact temperature is usually about 1/10 to 20 seconds, preferably
It is about 1/5 to 10 seconds. Activated carbon can be contacted with a sulfur compound-containing gas to remove sulfur compounds by known means such as a fixed bed, moving bed, fluidized bed, slurry system, batch system, or the like. In the method of the present invention, the oxidation reaction of the sulfur compound with oxygen is promoted by the activated carbon,
Hydrogen sulfide and carbonyl sulfide are efficiently converted to elemental sulfur or sulfuric acid, and mercaptans are efficiently converted to disulfides and the like. These products are more easily retained on activated carbon than the initial sulfur compounds;
Therefore, the ability of the alkali metal-supported activated carbon to remove sulfur compounds is greatly improved. One of the characteristics of the method of the present invention is that moisture in the gas or in the alkali metal-supported activated carbon significantly accelerates the oxidation reaction of the sulfur compound. The moisture content in the gas is between 10 and 90% relative humidity, preferably between 20 and 85%.
Further, the water content in the alkali metal-supported activated carbon is 5 to 50%, preferably 10 to 40%, on a weight basis. In the method of the present invention, if the alkali metal-supported activated carbon saturates and adsorbs sulfur compounds and its ability to remove sulfur compounds decreases, it can be easily regenerated by known solvent washing methods, thermal desorption methods, etc., and can be used again to remove sulfur compounds. Can be used. Particularly effective is the thermal desorption regeneration method, which is carried out at a temperature of 250 to 950°C in an atmosphere of inert gas such as nitrogen, carbon dioxide, or combustion gas, reducing gas such as carbon monoxide, hydrogen, or ammonia, or water vapor. . EXAMPLES The present invention will be described in more detail with reference to Examples below. In the examples, for example, “H ₂ S
``Amount of adsorption'' refers to the total amount of H ₂ S adsorbed on activated carbon, either as it is or in the form of other compounds, converted to H ₂ S based on sulfur. It is the amount of _H2S . The same applies to the amount of other compounds adsorbed. Example 1 Lignite with 48.3% fixed carbon, 49.5% volatile content, and 2.2% ash (alkali metal content 0.094%) is finely pulverized, and the alkali metal content in the resulting activated carbon is 1.0 to 5.0 mg.
- Powders of various alkali metal salts are added to finely powdered lignite at a concentration of atoms/g, mixed and ground, and then water,
Pitch etc. were added and kneaded, pressure molded into a 4 mm cylinder shape, carbonized at 600℃, and further activated in steam at 900℃ for 2 hours to activate carbon B, C (control) and D~
Q (the present invention) was obtained. Note that activated carbon A (control) was produced in the same manner without adding an alkali metal salt. 18 types of activated carbon (A
~ Pack 20 ml of Q) into a 4.0 cm column and add H ₂ S
Air at 25°C containing -1.0% by volume (relative humidity 80
%) was passed at a linear flow rate of 40 cm/sec for 6 hours at a temperature of 25° C., an H ₂ S adsorption experiment was conducted, and the results are shown in Table 1.

【table】

[Table] Example 2 Fixed carbon 84.4%, volatile content 13.4%, ash content 2.2% (alkali metal content 0.22%) instead of lignite in Example 1
Activated carbon a (control) was prepared by kneading, molding, carbonizing and activating coconut shells in the same manner as in Example 1, with or without adding various alkali metal salts.
and b to h (invention) were obtained. Eight types of activated carbon (a to
20 ml of h) under the same conditions as Example 1.
An H ₂ S adsorption experiment was conducted and the results are shown in Table 2.

[Table] Example 3 Activated carbons A and E of Example 1 and activated carbons a and d of Example 2 were crushed into 16/24 meshes, packed 0.7cm into a 1.6cm column, and containing 20ppm of H ₂ S. twenty five
C. air (relative humidity 80%) was passed through the tube at a linear flow rate of 40 cm/sec at a temperature of 25.degree. C. for 150 hours to determine the equilibrium adsorption amount of _H.sub.2S , and the results are shown in Table 3.

[Table] Example 4 Activated carbons a and d of Example 2 were crushed into 16/24 mesh, packed 0.7 cm into a 1.6 cm column, and CH ₃ SH-
CH ₃ SH
The equilibrium adsorption amount was determined and the results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. Obtained by adding alkali metal carbonates, sulfates, phosphates, halides, acetates, oxalates, benzoates, or salts of phenols to activated carbon raw materials and then carbonizing and activating this, per 1 g of activated carbon. 2.0
A malodor in a gas characterized by contacting activated carbon containing an alkali metal of mg-atom to 5.0 mg-atom with a gas whose main malodor component is at least one of hydrogen sulfide, carbonyl sulfide, mercaptans, and sulfides. How to remove.