JPS6057888B2 - Method for removing alkyl sulfides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing alkyl sulfides from a gas containing alkyl sulfides at low concentrations.

In the process gas or exhaust gas of petroleum refining, petrochemical, paper pulp, viscose rayon and other chemical industries, food industry, pharmaceutical industry, gas chemical industry, etc., or in the exhaust gas of sewage treatment plants, human waste treatment plants, chemical plants, etc. It contains hydrogen sulfide and various organic sulfur compounds, which give off a foul odor.

Various methods have been known to remove sulfur compounds from gases, such as an alkali absorption method, a wet oxidation method, an ozone oxidation method, an activated carbon adsorption method, and a combustion method. However, although these conventional methods can remove many sulfur compounds, they cannot completely remove alkyl sulfides, which give off a strong odor even at fairly low concentrations. The inventors of the present invention conducted various studies in view of the above circumstances, and as a result, discovered a method excellent in removing alkyl sulfides.

That is, the present invention provides a method for removing alkyl sulfides in a gas, which is characterized by contacting a gas containing substantially only alkyl sulfides as a malodorous sulfur compound component at a concentration of 10 ppm or less with activated carbon adsorbed with bromine. It is the law.

The above alkyl sulfide is a compound represented by the general formula R-S-R (R represents alkyl), and examples thereof include methyl sulfide and ethyl sulfide. In the present invention, the gas that is brought into contact with the activated carbon adsorbed with bromine is one that does not substantially contain malodorous sulfur compounds other than alkyl sulfide (e.g., hydrogen sulfide, carbonyl sulfide, alkyl mercaptan, etc.) and that contains alkyl sulfide at a concentration of 10 pμm or less. This includes: For example, oil refining, petrochemicals,
Conventional sulfur compound removal methods are used to remove process gases or exhaust gases from chemical industries such as paper pulp and viscose rayon, food industry, pharmaceutical industry, gas chemical industry, etc., or exhaust gases from sewage treatment plants, human waste treatment plants, chemical plants, etc. Processed J gas treated by can be applied to the present invention. The activated carbon used in the present invention is ordinary activated carbon made from charcoal, coconut shell, coal, etc., and has a BET surface area of 40
Particularly preferred are those with an Iy of 0 to 2,000 A, and particularly preferred are those having micropores with a diameter of 300 Λ or less and an average pore diameter of 10 to 30 A.

The activated carbon used is, for example, granular activated carbon such as spherical, cylindrical, or crushed activated carbon, powdered carbon, or activated carbon fiber, which has an appropriate shape and particle size depending on the deodorizing process.
The activated carbon used in the present invention is produced by adsorbing and supporting bromine on activated carbon by an appropriate method.

The amount of bromine adsorbed on the activated carbon is 0.02 m9 to 0.40 m9, preferably 0.05 m9 to 0.2 m9, per specific surface area d of the activated carbon measured by the BET method using nitrogen adsorption.

If the amount of bromine adsorbed is too small, a sufficient effect will not be exhibited, whereas if it is too large, bromine will be desorbed and the adsorption capacity of alkyl sulfide will also decrease. As a method for adsorbing bromine onto activated carbon, there are conventional adsorption methods, such as a vapor phase adsorption method in which a carrier gas containing monobromine gas is brought into contact with activated carbon, and a liquid phase method in which activated carbon is immersed in dibromine water. Examples include an adsorption method, and a method in which three liquid bromine is directly sprayed onto activated carbon to cause it to be adsorbed.

In the above gas phase adsorption method, the carrier gas is
Examples include air, nitrogen, and carbon dioxide gas. The mixing ratio of bromine gas and carrier gas is such that the concentration of bromine gas is usually 30% by volume or less, but preferably 0.05 to 2% by volume. Contact temperature is 150°C or less, preferably 80°C
It is as follows. In addition, since adsorption heat is generated during adsorption, it is preferable to consider the contact method and the temperature of the gas and adsorption container so that the temperature does not exceed 150°C. Such a method includes a continuous gas phase adsorption method in which a bromine-containing gas is circulated and brought into contact with a fluidized bed, moving bed, spouted bed, etc. of activated carbon. The remover obtained by adsorbing bromine in this way is
It is then desirable to flow a bromine-free carrier gas at a temperature of 100° C. or less to remove unadsorbed bromine. In the liquid phase adsorption method, the bromine concentration is 1
Activated carbon is immersed in a predetermined amount of ~3% bromine water and left in contact with stirring at a temperature of 50°C or less, preferably 30°C or less for about 1 to 1 hour, or a predetermined amount of bromine water with a concentration of 1% or less is added. The catalyst of the present invention can be obtained by contacting activated carbon in a fluidized bed, moving bed, fixed bed, spouted bed, etc., adsorbing bromine, separating it with p, and drying. In addition, in the method of spraying liquid bromine onto activated carbon, the removing agent of the present invention can be obtained by spraying liquid bromine or bromine water directly onto activated carbon while stirring and drying if necessary.

The temperature when spraying liquid bromine or bromine water is preferably 50°C or lower. When preparing bromine water in the above liquid phase adsorption method and spraying method, for example, ammonium bromide,
When ammonium salts, alkali metal salts, and alkaline earth metal salts of bromine such as sodium bromide, potassium bromide, and calcium bromide are dissolved in water at 5 to 15% by weight, and bromine is dissolved in this, a large amount of bromine can be dissolved. This method is convenient for operation because it requires less water, and evaporation of highly toxic bromine can be suppressed.

The activated carbon adsorbed with bromine prepared in this way can be used in fixed bed, moving bed, fluidized bed, slurry method,
The alkyl sulfide is adsorbed and removed by bringing it into contact with the gas to be treated using a known method such as a batch type contact stirring method.

The contact temperature is usually 0 to 50°C, preferably 15 to 30°C. The contact time varies depending on the particle size of the activated carbon, for example, a particle size of 4Tfr! For granular coal of about n size, the time is usually 0.1 seconds or more, but for powdered coal, it is possible to take about 0.01 seconds.
By treating a gas containing alkyl sulfide with the method of the present invention, the alkyl sulfide can be removed from the gas to such an extent that the odor of the alkyl sulfide is no longer felt.

Furthermore, in the method of the present invention, especially when treating soot gas containing alkyl sulfide at a low concentration, the removal effect is more remarkable than in the conventional method. The present invention will be explained in detail below with reference to Examples.

Example 1 BET surface area 1200 Iy 4 to 6me
sh activated carbon 50y with inner diameter 6c)T! r! ! A glass column of t is filled in a layered manner to form a gas flow path of a closed circulation system via a pump, a gas mixing pin, and an activated carbon-filled column.

While circulating the dry air in the system at a flow rate of 30 eImin, a predetermined amount of liquid bromine is introduced into the gas mixing pin at a rate of 0.5 eImin and volatilized, and the introduced bromine is adsorbed on activated carbon. In this way, various adsorbents having different amounts of bromine adsorption were prepared as shown in Table 1. Prepared sample for 8-14mes
Crush and size the particles to 100T in a glass column with an inner diameter of 15.6Tf$t! Fill up to Rln and add 2p methyl sulfide.
Air with a humidity of 80% including pm at a temperature of 25°C and a gas flow rate of 2
It was allowed to flow at 0 cmIsec, and the breakthrough curve of methyl sulfide was determined. 10 (After flowing between Ff, the equilibrium adsorption amount of methyl sulfide was determined for the bromine-adsorbing activated carbon up to a 1 cm layer from the gas inlet.

The results are shown in Table 1. Note that the treated gas (the gas that came into contact with the bromine-adsorbing activated carbon) did not have any methyl sulfide odor.

Claims (1)

[Claims] 1. A method for removing alkyl sulfides in a gas, which comprises contacting a gas containing substantially only alkyl sulfides as a malodorous sulfur compound component at a concentration of 10 ppm or less with activated carbon adsorbed with bromine.