JPH05337324A - Filter for purification of gaseous product containing acid gas - Google Patents

Abstract

PURPOSE:To purify a gaseous product containing acid gas generated locally on a small scale for a long time by first impregnating a gas-permeable metal porous product with a basic solution, then drying it, and allowing a basic substance to be carried by the skeleton and gas hole parts of the product. CONSTITUTION:The filter consists of a gas-permeable metal porous product which is obtained by sintering metal fine particles 1 and impregnated with a basic solvent, with a drying procedure, and further, which has a skeleton part 2 and a gas hole part 3 carrying a basic substance 4, 5. The percentage of micro voids (the volume of a porous part between particles in a sintered tissue/the total volume of the sintered tissue)X100 of the porous product should preferably be within a range of 15 to 40%, as there is the necessity to impregnate the porous product with an adequate amount of basic solution required for neutralization reaction. Thus the filter has adequate properties and enough strength for handling, so that it can treat a gaseous product containing acid gas for a long time. In addition, the filter already used, can be recycled for use by treating it as described above after water wash.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter for cleaning a gas containing an acidic gas. In detail,
For example, the present invention relates to a filter that neutralizes and detoxifies acidic gas containing acid gas at the time of pickling in a metal component plating step or locally generated acidic gas-containing gas such as acrylic acid scattered in an acrylic paint spraying step.

[0002]

2. Description of the Related Art Pickling process in metal parts plating process,
In the acrylic paint spraying process, etc., acidic gas such as cleaning acid or acrylic acid is generated, and in the place where such acidic gas is generated on a large scale, in order to purify this, a gas-liquid reaction type The gas containing the acidic gas is blown directly into the alkaline aqueous solution using a Japanese reaction vessel.

However, in such a cleaning system, the neutralization reaction device is remarkably large in size, and since it is necessary to install a treatment device for the solution after the neutralization reaction, the equipment is large in size and expensive. Become. For this reason, it is not preferable as a method for treating the small-scale locally generated acid gas-containing gas from the economical viewpoint. Therefore, there has been a demand for a small-scale and simple method for treating a gas containing an acidic gas.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a novel filter for cleaning a gas containing an acidic gas.

The present invention is also suitable for purification of a small-scale locally generated acid gas-containing gas, which can be used for a long period of time and can be used as a device with low equipment cost and running cost. It is intended to be provided.

[0006]

According to the present invention, a breathable metal porous body obtained by sintering a metal powder is impregnated with a basic solution and then dried, and a skeleton portion of the breathable metal porous body and The acidic gas-containing gas cleaning filter is characterized in that the basic substance is carried in the pores.

[0007]

The inventors of the present invention impregnated a basic solution into a breathable metal porous body produced by sintering a metal powder having an average particle size of 20 μm or less, preferably 5 to 15 μm, and then dried, On the surfaces of the skeleton portion (branch portion forming the porous body) of the air-permeable porous body and the pore portions (pore portions between the sintered particles),
The inventors have found that the acidic gas can be removed extremely efficiently by passing the acidic gas-containing gas through a filter formed by protruding a basic substance.

Next, an example thereof will be shown. That is, 1 g ³ of a gas containing 200 ppm of an acrylic acid monomer was impregnated with 30 g of sodium hydroxide in a hermetically sealed container, and the sodium hydroxide was extruded to form a breathable metal porous body (1
(50 mm × 100 mm × 10 mm) was installed and a gas was circulated through the gas permeable metallic porous body at a passage speed of 0.4 m ³ / min. After 30 minutes, acrylic acid was completely removed.

As described above, the action of the acid gas being extremely effectively removed by the gas-solid contact reaction and the neutralization reaction is shown in the microscopic structure magnified 300 times in FIG. Microscopically, basic substances 4 and 5 are carried on the respective surfaces of the porous body skeleton 2 produced by sintering the metal fine particles 1 and the extremely porous porous body pore portion 3 formed thereby. This is probably because the specific surface area of the basic substance could be made extremely large.

On the other hand, as a method of increasing the specific surface area of the basic substance, it is possible to use a powder of the basic substance or to use beads in which the basic substance is supported on a small carrier. In this case, a neutralization reaction product of an acidic gas and a basic substance is generated on the surface of the beads, and particles or beads are bound to each other, so that the air permeability is significantly reduced and the filter cannot be used. turn into.

On the other hand, in the case of a ceramic breathable porous body, if the microporosity is increased by 10% or more in order to increase the impregnation amount of the basic solution, the strength becomes weak and it becomes unusable. ..

The air-permeable porous metal material used in the present invention has an average particle size of 20 μm or less, preferably 5 to 15 μm.
The metal powder of m is coated on a porous organic polymer body such as polyurethane foam and is sintered in a non-oxidizing atmosphere to melt and remove the organic polymer porous body to form a metal porous body. It is a thing. As the metal used, iron is the main component, and in addition, manganese, chromium,
It may contain a metal such as copper, nickel, tin, or zinc that improves corrosion resistance.

Since it is necessary to sufficiently impregnate the air-permeable porous body with a basic solution necessary for the neutralization reaction, the microporosity of the porous body [(inter-particle porous portion in the sintered structure is volume/
Total volume of sintered structure) × 100] is 15 to 40%, especially 20
The range of up to 30% is preferred. That is, if the microporosity is less than 15%, the basic solution cannot be sufficiently impregnated, so the life of the filter is shortened, while if it exceeds 40%,
It is not suitable for practical use because the binding of the sintered particles is weak and it easily collapses.

The basic solution used in the present invention is, for example, an aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, sodium carbonate, calcium carbonate, lithium carbonate, sodium hydrogen carbonate, calcium hydrogen carbonate or the like. Is preferable, and a saturated solution is preferable, and it is most preferable in terms of operation. The amount of the basic substance supported after drying is
0.05-0.5 g / cm ³ , preferably 0.1-0.
It is 3 g / cm ³ .

In the cleaning filter thus obtained, the acidic gas in the gas is neutralized and removed by circulating the acidic gas-containing gas. Further, in the filter, after most of the basic substance is consumed by the acid gas for the neutralization reaction, the filter is washed with water to wash off the neutralization reaction product, then impregnated with the basic solution again and dried. It can be used repeatedly.

[0016]

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

EXAMPLE A pig iron fine powder having an average particle size of 10 μm was applied to a polyurethane foam using polyvinyl alcohol as a binder,
An iron-based sintered porous metal porous body was produced by sintering in a nitrogen atmosphere at a temperature of 1240 ° C. and used as a filter of 4 cm × 4 cm × 3 cm (weight: 40 g).

The microporosity of this product was 23%. After impregnating this filter with an aqueous solution obtained by dissolving sodium hydroxide in 20 ml of water,
After drying in the air, a filter for cleaning a gas containing an acidic gas was obtained.

The cleaning filter 11 thus obtained is used in the experimental apparatus shown in FIG.
2. A flowmeter 13, a pipe 14 for measuring the concentration on the inlet side, and a pipe 15 for measuring the concentration on the outlet side are stored in a cleaning chamber 16 of an experimental apparatus, and 30 ppm of acrylic acid is charged by a cylinder.
When a gas containing P was passed through at a flow rate of 2 liters / minute, the acrylic acid concentration on the outlet side was removed over a long period of time as shown in Table 1.

After being used for 30 hours, this cleaning filter was washed with warm water and then treated with a basic solution in the same manner as above, and the same test as above was carried out. ), The performance was almost the same as the first case.

[0021]

[Table 1]

[0022]

As described above, according to the present invention, the skeleton of the breathable metal porous body is obtained by impregnating the basic solution of the breathable metal porous body obtained by sintering the metal powder and then drying. Since it is a filter for cleaning an acidic gas-containing gas, in which the basic substance is supported on the pores and pores, it is possible to clean the acidic gas-containing gas that is locally generated on a small scale at a low running cost for a long period of time and It can be implemented with low equipment costs. Further, since the filter has properties and strength sufficient for handling, it is possible to process the acid gas-containing gas for a long time. Furthermore, there is an advantage that the filter after use can be repeatedly used by washing with water, impregnating with a basic solution again, and drying.

[Brief description of drawings]

FIG. 1 is a micrograph showing a cross section of a filter for cleaning a gas containing an acidic gas according to the present invention at a magnification of 300 times.

FIG. 2 is a conceptual diagram showing an experimental apparatus for cleaning a gas containing an acidic gas according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal fine particles 2 ... Porous body skeleton 3 ... Porous body pore part 4, 5 ... Basic substance 11 ... Filter 12 for cleaning 12 ... Gas cylinder 13 ... Flowmeter 14 ... Pipe for measuring concentration on the inlet side 15 ... On the outlet side Piping for concentration measurement 16 ... Cleaning room

Claims (2)

[Claims] 1. A permeable metal porous body obtained by sintering a metal powder is impregnated with a basic solution and then dried, and the skeleton and pores of the permeable metal porous body are coated with the basic substance. A filter for cleaning a gas containing an acidic gas, which is carried. 2. The porous microporous material has a microporosity of 1
The acid gas-containing gas cleaning filter according to claim 1, which is 5 to 40%.