JPH0157617B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to mercury vapor adsorbents in gases.
Mercury vapor is often contained in electrolyzed hydrogen gas, natural gas, incinerator exhaust gas, and exhaust gas from factories that handle mercury. In other words, electrolytic hydrogen is used for pharmaceuticals,
It is used in the process of manufacturing food and other products, and trace amounts of mercury vapor can cause problems as it can poison catalysts or mix into products. Mercury vapor in natural gas corrodes aluminum heat exchangers during the gas liquefaction process, causing major accidents. Furthermore, mercury vapor in incinerator exhaust gas and exhaust gas from factories that handle mercury vapor poses problems in terms of air pollution and the working environment. Therefore, mercury vapor in these gases must be removed by some kind of treatment. Until now, known methods for removing mercury from gas include chemical cleaning methods and dry adsorption methods using adsorbents such as activated carbon and ion exchange resins. There are disadvantages such as insufficient removal efficiency and generation of waste liquid. The latter dry adsorption method has a small adsorption capacity for mercury vapor and is not fully satisfactory. In view of these points, the present inventors conducted research and found that activated carbon supporting ammonium thiocyanate, ammonium thiosulfate, ammonium sulfide, and ammonium sulfamate efficiently adsorbs mercury vapor in gas and has a high adsorption capacity. They discovered that the capacity was significantly large and completed the present invention. That is, the present invention is a mercury vapor adsorbent comprising activated carbon supporting at least one of ammonium thiocyanate, ammonium thiosulfate, ammonium sulfide, and ammonium sulfamate (hereinafter referred to as ammonium salt). The activated carbon used in the present invention is produced by a known method using charcoal, coke, coconut shell, resin, etc. as raw materials, and has a specific surface area of 200 to 200.
Any material may be used as long as it has an area of 2000m ² /g. The amount of ammonium salt supported on activated carbon is 5 to 800 mg, preferably 10 to 550 mg per gram of activated carbon. In order to support the ammonium salt on the activated carbon, for example, a method of dissolving the ammonium salt in water, impregnating or spraying the ammonium salt on the activated carbon, and drying as necessary can be mentioned. The mercury vapor adsorbent of the present invention may carry a nonvolatile acid in addition to the ammonium salt, and by supporting the nonvolatile acid, the mercury adsorption ability of the adsorbent can be increased. The non-volatile acid referred to herein refers to an acid with a vapor pressure of 50 mmHg or less at 100°C, such as sulfuric acid, phosphoric acid, oxalic acid, and citric acid. The amount of nonvolatile acid supported is 5 to 500 mg, preferably 10 to 500 mg per gram of activated carbon.
It is 400mg. The method for supporting non-volatile acids is as follows:
This is carried out in the same manner as the method for supporting ammonium salts on activated carbon, and the order in which ammonium salts and nonvolatile acids are supported on activated carbon may be arbitrary. For example, a method of impregnating or spraying activated carbon with an aqueous solution containing an ammonium salt and a non-volatile acid, a method of supporting an ammonium salt and then supporting a non-volatile acid, or a method of supporting a non-volatile acid and then supporting an ammonium salt. Examples include methods. In order to remove mercury vapor from a gas using the mercury vapor adsorbent of the present invention, it is sufficient to bring the gas containing mercury vapor into contact with the adsorbent of the present invention. The contact temperature is 150°C or less, preferably -10 to 120°C, and the contact pressure is 50Kg/ ^cm2 or less, preferably 0.1 to 35Kg/ ^cm2.
The contact time is 1/10 to 30 seconds at 25°C in terms of 1 kg/ ^cm2 .
Preferably it is 1/5 to 20 seconds. In addition, the contact between the present adsorbent and the mercury vapor-containing gas can be carried out, for example, by using a fixed layer,
This can be carried out using a moving bed, fluidized bed, etc. EXAMPLES The present invention will be explained in more detail with reference to Examples below. Example 1 Granular activated carbon of 4 to 6 mesh with a BET specific surface area of 1150 m ² /g was crushed and sized to 16 to 24 mesh. NH ₄ SCN, (NH ₄ ) ₂ S ₂ O ₃ , (NH ₄ ) ₂ S and
Spread an aqueous solution containing NH ₄ OSO ₂ NH ₂ uniformly to support 100 mg/g of each of NH ₄ SCN, (NH ₄ ) ₂ S ₂ O ₃ , (NH ₄ ) ₂ S, and NH ₄ OSO ₂ NH ₂ death,
Dry at 110°C (adsorbents BE). As a control, 100 mg/g of each sodium salt was supported in place of these ammonium salts in the same manner as above and dried at 110°C (adsorbents b to e). Further, a carbon disulfide solution containing sulfur dissolved in activated carbon A was sprayed and dried at 120° C. to prepare activated carbon supporting 100 mg/g of sulfur (adsorbent f). Adsorbents A to E and b thus obtained
6 ml ^of _each of ~
84.8 ^vol %, O ₂ -14.5 ^vol %, H ₂ O - 0.7 ^vol %) were passed at a linear flow rate of 40 cm/sec to conduct a breakthrough adsorption test for mercury vapor. The results are shown in Table 1.

【table】

[Table] Example 2 Adsorbents B to E and b to e of Example 1 were further loaded with 100 mg/g of sulfuric acid and dried at 110°C (adsorbents B ₁ to E ₁ and b ₁ to e ₁ ). The thus obtained adsorbents A to E, B ₁ to
6 ml each of E ₁ , b to e, and b ₁ to _{e 1} was packed into a 1.6 cmφ glass column, and nitrogen gas at 30°C containing 9 mg/m ³ of mercury vapor was passed through at a linear flow rate of 40 cm/sec.
A breakthrough adsorption test for mercury vapor was conducted. The results are shown in Table 2. Example 3 Activated carbon A (16-24mesh) of Example 1
5, 10, 50, 100, 200, 400, 500 and 550 mg/g of NH ₄ SCN were supported and dried at 110°C. 1.5 ml of each 6 ml of the adsorbent thus obtained
Packed into a cmφ glass column, mercury vapor 9
mg/m ³ of gas at 30 °C (N ₂ −84.8 ^vol %, O ₂ −14.5 ^vol
%, H ₂ O-0.7 ^vol %) at a linear flow rate of 40 cm/sec for 300 hours, the amount of mercury adsorbed on each adsorbent was measured, and the results are shown in Table 3.

【table】

[Table] Example 4 Activated carbon A (16-24mesh) of Example 1
125 mg/g of NH ₄ SCN was supported and dried at 110°C.
Furthermore, 50 mg/g of each of sulfuric acid, phosphoric acid, oxalic acid, and citric acid were supported and dried at 110°C. Each 6 ml of the adsorbent thus prepared was
Packed into a 1.6 cmφ glass column, mercury vapor 9
A breakthrough adsorption test for mercury vapor was conducted by flowing nitrogen gas containing mg/m ³ at 30°C at a linear flow rate of 40 cm/sec.
The results are shown in Table 4.

[Table] Example 5 Each 6 of adsorbents B to E and B ₁ to E ₁ of Example 2
ml was packed into a 1.6 cmφ glass column, and hydrogen gas at 30°C containing 1 mg/ ^m3 of mercury vapor was applied at a linear flow rate of 40°C.
cm/sec, and a breakthrough adsorption test for mercury vapor was conducted. The results are shown in Table 5.

【table】

Claims (1)

[Scope of Claims] 1. A mercury vapor adsorbent comprising activated carbon supporting at least one of ammonium thiocyanate, ammonium thiosulfate, ammonium sulfide, and ammonium sulfamate. 2. The mercury vapor adsorbent according to claim 1, which carries a nonvolatile acid together with at least one of ammonium thiocyanate, ammonium thiosulfate, ammonium sulfide, and ammonium sulfamate.