JPS58133820A - Treatment of waste gas - Google Patents

Abstract

PURPOSE:To remove SOx and NOx in waste gas efficiently by incorporating ammonium salts in a raw material for active carbon, carbonizing and activating the same and bringing the active carbon into contact with the waste gas. CONSTITUTION:First, ammonium salt is incorporated in the raw material for active carbon. Ordinary raw material for the active carbon such as charcoal is used, and ammonium sulfate or the like is used for the ammonium salt. The amt. of ammonium salt to be contained to the raw material for the active carbon is about 0.1-50wt% based on the weight of the active carbon. After the mixture is kneaded, the mixture is molded under pressure. The molding is carbonized at about 400-800 deg.C and then activated with steam, carbon dioxide or the like at about 800-1,000 deg.C. Such active carbon is brought into contact with waste gas to remove SOx and/or NOx in the gas. The contact temp. is regulated to about <=150 deg.C, the gaseous pressure to about 30kg/cm<2>, and the contact time to about 0.1-30sec.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating exhaust gas containing sulfur oxides and nitrogen oxides.

In recent years, exhaust gas from thermal power plants, chemical plants, pot smelting plants, metal cleaning plants, etc. contains sulfur oxides, nitrogen oxides, etc., which pollute the atmosphere and pose a major problem for companies. There is. For this reason, various processes for removing sulfur oxides and nitrogen oxides from exhaust gas have been studied, and research into practical application is underway.

Recently, due to sudden changes in the fuel situation, activated carbon has been used again in a process to remove K802 sulfur oxides from exhaust gas.
The so-called activated carbon method flue gas desulfurization is attracting attention, and research into its practical application is being actively conducted. Activated carbon desulfurization can be roughly divided into wet desulfurization, water washing desulfurization, and thermal desulfurization. Each method has its own characteristics, but all of them convert SO2 in exhaust gas into F[2804]. When converting,
Activated carbon is required to have high catalytic activity. Conventional activated carbon does not have sufficient catalytic activity, and when used for a long period of time, the catalytic activity of activated carbon decreases significantly.

For this reason, the desulfurization equipment becomes large, and the activated carbon must be replaced after a certain period of continuous operation, which has the disadvantage of increasing the desulfurization cost. One method to improve the desulfurization performance of activated carbon, such as catalyst activity and catalyst life, is to impregnate activated carbon with a metal, but this lowers the ignition point of activated carbon, and wet desulfurization and water washing desulfurization methods However, there are drawbacks such as leaching of metals.

As a result of various studies to solve the above-mentioned problems, the inventor of the present invention mixed ammonium sediment into the activated carbon raw material, expanded it, and activated it. was found to have catalytic activity against.

That is, the present invention, when removing sulfur oxides and /f or nitrogen oxides in exhaust gas, brings the exhaust gas into contact with activated carbon obtained by mixing ammonium salt into activated carbon raw material, carbonizing and activating the mixture. This is a distinctive feature of the exhaust gas treatment method.

The above sulfur oxides are commonly called SOx, and are mainly [
902, and nitrogen oxides are commonly called NOx and are mainly a mixture of N0 and No2.

The activated carbon used in the present invention can be produced as follows.

First, ammonium salt is mixed into the activated carbon raw material.

The raw material for activated carbon can be any material that is normally used in the production of activated carbon, such as wood, coconut shell, wood acid charcoal, etc. Examples of the ammonium salts include ammonium salts of inorganic acids such as ammonium sulfate, ammonium nitrate, ammonium halides (N, ammonium chloride, ammonium bromide, ammonium miride, etc.), and ammonium salts of organic acids such as ammonium acetate and ammonium oxalate. A litter box is provided. The amount of ammonium salt O mixed into the activated carbon raw material is 0.1 per activated carbon raw material.
from 1.0 to 50% by weight, preferably from 1.0 to 30% by weight
It is.

The desired activated carbon can be obtained by mixing the ammonium salt into the activated carbon raw material, kneading it, press-molding it by a conventional method, and then carbonizing and activating it. Carbonization and activation may be carried out according to the well-known activated carbon manufacturing method, for example, after carbonization at a temperature of about 400 to 800°C, activation may be performed at a temperature of 800 to 1000°C with steam, carbon dioxide gas, etc.

The present invention is carried out by bringing the thus obtained activated carbon into contact with exhaust gas. The contact method is carried out using, for example, a fixed bed, a moving bed, a flowing a bed, etc., the contact temperature is 150°C or less, preferably 0 to 120°C, and the gas pressure is usually 30kg/C112 or less, preferably O,1
~20 kg/rv2, contact time is 0.61 to 30 seconds, preferably 0.2 to 15 seconds.

According to the present invention, sulfur oxides and nitrogen oxides in exhaust gas can be efficiently removed, and the activated carbon used has a long catalyst life.

EXAMPLES The present invention will be described in more detail with reference to Examples below.

Example/ Finely ground coal IQ kgK of 50 to 200 mesh
2 kg of pitch as a binder, some water, and 500 g of each of the ammonium salts listed in the following table were added, mixed and kneaded without further addition, and then pressure molded. The molded products were carbonized at 600°C and further activated at 850°C in the presence of water vapor to obtain various activated carbons having approximately the same surface area.

Fill a cuff with a diameter of 11 with 2 g of each catalyst for 1 J.
CL, 5o2-o, 1vO1g, o, -s, 5
vO15%, l'! 20-10.0”15%, N2
-83.4” 1X Nofi Sha Cast TTS Flow Ren 30 CVA
/ 81! 9. Adsorb SO2 at 130°C for 8 hours with IO. After adsorption, the activated carbon was heated at 70°C for 2 hours.
Regenerated by extraction in 0cc of water, after regeneration,
The above adsorption operation was performed again.

The 802 adsorption amount of activated carbon is the OI of H2SO4 in the extract.
It was calculated by neutralizing with N NaOH and converting it into sop.

By repeating the adsorption/regeneration operation, the relationship between the number of cycles and the amount of SO2 adsorbed in each cycle for each activated carbon can be summarized as follows.

Example λ The same S02 adsorption as in Example X is carried out on the activated carbons A, B and F obtained in Example/. After adsorption of 802, the activated carbon was heated for 30
It is regenerated by heating at 0°C for 1 hour, and the S02 desorbed at this time is collected with a 3% H2O2 aqueous solution.
N (DlfaOHf) was neutralized, the S02 amount was calculated, and this was taken as the 802 adsorption amount. 802 adsorption was performed again on the regenerated activated carbon.

When such adsorption/regeneration operations are repeated nine times, the relationship between the number of cycles and the amount of S02 adsorbed in each cycle for each activated carbon is as follows.

Example 3 Implementation fl! The activated carbon obtained in B and rt- was packed in a column with a diameter of 5C@ to a bed height of 15 cm.

Adjust the temperature of this cuff to a constant temperature of 60°C.
After 90 minutes, thoroughly moisten the activated carbon with warm water at 60℃.
C1802-0,1vO1 from the top of the column while pouring warm water at ℃ from the top of the column at a flow rate of 1,Qg/win.
%', 02-6.5vO15%, H2O-10, 6
vo1g, 'N2-83.4vOIX ノ120℃o
The gas was distributed at a linear flow rate of 10 cm/see. After 2 hours for each activated carbon, the desulfurization rate and the effluent FI2SO4 were
At 11 degrees, it turned out to be a bummer, and we got the following results.

Example 2 Each of active pA, B and F obtained in Example 2 and 2
Fill a cuff 5 with a diameter of 1 cm with N0x (No-50
%, No2-50 amount%)-0,06v01X, H2
O-3,0"1X IAir-96,94v0'X (
D 50 T: (Da combination xxtts flow s10cs/se
Distributed in a, 5 hours, Nox] inhalation jltf? became.

After adsorption, hot water at 50° C. is poured onto the activated carbon at a rate of 200 CC/hr for 4 hours to regenerate the activated carbon.

The NO2 adsorption dragon is
-0NaOF! Neutralize it, NO2! ! ! ! Calculated by calculating.

When such adsorption/regeneration operations are repeated, the relationship between the number of cycles and the amount of NO2 adsorbed in each cycle for each activated carbon is as follows.

Example! NoX was adsorbed on the activated carbons B and F obtained in Example 9 in the same manner as in Example 9.

NoX0 adsorption IIO activity linear flow rate 0, 3 cL/B
@c) Regeneration by heating at 150° C. for 1 hour in a N2 stream) At this time, the amount of No desorbed was determined and converted into No2, and this was defined as 11 amount 2 adsorption amount. After regeneration, NOx adsorption was performed again.

When such adsorption/regeneration was repeated nine times, the relationship between the number of cycles and the amount of 102 adsorbed in each cycle is shown below for each activity 1'.

Claims (1)

[Claims] When removing sulfur oxides and/or nitrogen oxides from exhaust gas, the exhaust gas is brought into contact with activated carbon obtained by mixing an ammonium salt into an activated carbon raw material, solidifying it, and activating it. processing method.