JP2005169293A5 - - Google Patents

Description

Method for oxidizing or decomposing organic matter

The present invention relates to a method for oxidizing or decomposing organic substances other than solids .

  Recently, the treatment of organic substances such as plastics has become a major social problem. This is mainly because plastic does not decompose as it is, it cannot be solved by landfill, and the landfill site is disappearing.

  Such processing of plastics and the like has conventionally been an incineration method. Incineration is burning at high temperature in a furnace to produce carbon dioxide and other oxides.

However, in the combustion method, there is a risk that toxic gas is generated unless complete combustion is performed. Therefore, the fuel is inevitably burned at a high temperature. Therefore, since unnecessary fuel is also incinerated, the surrounding environment is heated and carbon dioxide is unnecessarily generated.
Furthermore, it is difficult to completely suppress the generation of dioxins.

Thus, the inventors have devised a method for oxidizing and decomposing plastics at a relatively low temperature using a photocatalyst and have filed a patent application.
In this method, plastic fragments are mixed with heated photocatalyst powder, which is an excellent method for easily decomposing plastics at low temperatures.
JP 2002-363337 A

  However, in this method, an electromagnetic wave irradiation device such as ultraviolet rays is indispensable, and the device (lamp) is vulnerable to heat, and it has been necessary to use expensive quartz glass or put it in a light-transmitting cooling pipe. .

  Therefore, a method is provided in which an organic substance can be oxidized or decomposed in as short a time as possible, and an expensive apparatus can be reduced as much as possible.

In view of the present situation as described above, the present inventor has completed the method for oxidizing or decomposing the organic matter of the present invention as a result of intensive research, and the feature thereof is that the heated photocatalyst particles include organic matter other than solid. introduced by the photocatalyst and the oxygen activated by heating lies in decomposing the organic substances other than the solid.

The inventors of the present invention have overturned the common knowledge that the photocatalyst is activated only by irradiation with light (electromagnetic waves) from the name photocatalyst by conducting various experiments on the photocatalyst. In other words, it was found that the photocatalyst is activated by heating even if it is not irradiated with electromagnetic waves, and oxidizes or decomposes organic matter if there is an oxidation source.
This solves the problems such as the ultraviolet lamp is weak and often exchanged as described above, or expensive heat insulation means is necessary, or the photocatalyst is deeply filled and the electromagnetic wave does not easily reach the lower layer. It is a breakthrough.

  Conventionally, the advantage of a photocatalyst that can be oxidized and decomposed at a low temperature compared to a high-temperature oxidation catalyst has been praised. It was outside.

Here, organic substances other than solids include not only liquids such as fats and oils and organic solvents, but also toxic substances such as PCBs. The organic matter is not limited to low molecules and polymers. Further, a gas may be used. For example, malodorous gases from factories and poultry farms, or cracked gases from organic matter decomposing devices may be used. In short, any organic material other than solid may be used.

In the case of a liquid, it is preferable to spray from the top of the photocatalyst particles heated and filled, but it may be sprayed into a reactor in which the photocatalyst is suspended.
In the case of gas, it is only necessary to pass between heated photocatalyst particles.

As the photocatalyst, anatase type crystals of titanium oxide are generally well known, but other photocatalysts may be used. In short, it undergoes a photo-oxidation reaction upon receiving electromagnetic waves (such as ultraviolet rays and visible light).
The smaller the particle, the better the efficiency of the photocatalyst. Therefore, usually several nm to several μm are suitable, but the special size is not limited. In addition, the fine powder soars or comes out of the system with the gas, so it may be supported on a carrier.

The carrier may be any particles such as silica sand. Moreover, not a particle but a fibrous thing may be sufficient. The size is not particularly limited, but is preferably 10 mm or less, preferably several μm to 6 mm, and more preferably about 10 μm to 1 mm.
As a method of fixing to the carrier, adhesion may be made with a fluorine-based resin or a silicon-based resin that is not easily decomposed. Moreover, it is thought that the catalyst efficiency improves as a whole when titanium alkoxide is used as an adhesive. The same applies when crushing.
The size of this adhesive granulation type is also free but is preferably about 10 μm to 10 mm.

Further, both a water-based resin (water-soluble resin or emulsion-type resin) and cement (all those cured by a hydraulic reaction) may have a photocatalyst fixed to a carrier.
In the fixing method, first, an aqueous resin is applied to the carrier, and then the cement and the photocatalyst are fixed. First, the cement or photocatalyst is fixed by the initial adhesive strength of the water-based resin. And if a cement hardens | cures, even if an aqueous resin is decomposed | disassembled by the oxidizing power by a photocatalyst, it will be hold | maintained by the cement.
The amount to be attached is arbitrary and does not depend on the method of attachment, but it is usually about 1% to 10% of the weight of the carrier due to the difference in size with the carrier.

  Photocatalyst particles can be filled in a reactor, in a mesh-like container and installed in the reactor, supported by a filter, or suspended in the reactor. Good.

  The filter here simply means that the passage is a large number of small holes. Therefore, any material such as particles, cloth, non-woven fabric, sponge, porous material, etc. may be used. This filter carries a photocatalyst. As a supporting method, a fluorine-based resin or a silicon-based resin which is not easily decomposed may be used, or may be fixed with an inorganic adhesive. Further, it may be fixed with both the aqueous resin and cement. The shape can be freely selected, for example, a block or plate made of a net filled with photocatalyst-supporting particles, or a frame in which photocatalyst particles are fixed to the cloth or nonwoven fabric described above.

  The heating temperature is determined by the type of organic matter to be decomposed and the shape and size of the photocatalyst. Usually, it is 50-600 degreeC, However, 100-450 degreeC, Especially 150-350 degreeC is suitable. This is due to the balance between decomposition efficiency, heating costs and other factors.

  Any heating method may be used as long as the photocatalyst particle layer can be heated. Electric heaters, gas burners, etc. It is preferable to control the temperature by providing a temperature control device.

  There is no problem as long as oxygen (air) is sufficient to oxidize organic matter in the container filled with the photocatalyst. However, if it seems to be insufficient, it is introduced separately from the air introduction pipe. If oxygen is included, it does not have to be air.

  Oxidation is a reaction in which ammonia becomes nitric oxide, and decomposition here means that a polymer becomes a low molecule. One or both of these occur and the organic matter changes. The changed products are mostly carbon dioxide and water, but naturally nitrogen and sulfur oxides are also generated if the raw material contains nitrogen and sulfur. These may be processed in a later step.

  Moreover, it is not necessary to completely oxidize or decompose organic substances by the method of the present invention. That is, there is no problem even if undecomposed or unoxidized material remains. Therefore, you may employ | adopt as a rough decomposition method of the pre-processing of another processing apparatus. In particular, since the present invention is simple and the apparatus can be inexpensive, such a pretreatment method is very excellent.

  The oxidation or decomposition method of the present invention can be carried out either continuously or batchwise. Further, when a tar-like material or carbon adheres to the surface of the used photocatalyst, it may be discarded or regenerated, but is not directly related to the present invention.

The method of the present invention has the following great advantages.
(1) The photocatalyst can be efficiently oxidized or decomposed.
(2) Despite the use of a photocatalyst, an electromagnetic wave irradiation device (such as an ultraviolet lamp) is unnecessary.
(3) It can be implemented with a very simple device.

  Hereinafter, the present invention will be described in more detail based on preferred examples.

FIG. 1 is a schematic cross-sectional view showing an example of an apparatus 1 for carrying out the organic substance oxidation or decomposition method of the present invention. Here, a solid is used as the organic substance to be decomposed, but a liquid or gas is easier if the solid can be decomposed. This is because the solid is considered to be oxidized or decomposed once it becomes liquid or gas.
Photocatalyst particles 3 are packed in the reactor 2. The particle 3 is obtained by granulating fine powder into a size of 0.5 mm. A cooling coil 4 is installed in the photocatalyst layer. In this, air or water passes through the inside, and the catalyst layer is cooled. This is for cooling when the temperature rises excessively due to the oxidation reaction.

  A burner 5 is provided below. This is also temperature controllable. The reactor 2 is provided with an organic substance inlet 6, an air inlet 7, and an outlet 8. These may be opened continuously or intermittently.

  First, an organic substance (here, a crushed piece of plastic) is introduced from the organic substance inlet 6. At the same time, air is introduced. The catalyst and the organic substance are mixed and stirred by a stirring device (not shown) in the catalyst layer. Since the catalyst is heated (in this example, 400 ° C.) and activated, it reacts with oxygen and the plastic is decomposed into a low molecular gas.

  After the discharge port 8, the atmosphere may be released or another processing step may be performed.

It is a schematic sectional drawing which shows an example of the apparatus which enforces this invention method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic substance decomposition | disassembly apparatus 2 Reactor 3 Photocatalyst particle 4 Cooling coil 5 Burner 6 Organic substance inlet 7 Air inlet 8 Outlet

Claims (3)

During the heated photocatalyst particles, introducing the organic substance other than a solid, the photocatalyst and the oxygen which is activated by heat, oxidation or decomposition method of organic substances, characterized in that the oxidizing or decomposing organic matter other than the solid.   The method for oxidizing or decomposing organic substances according to claim 1, wherein the heating temperature is 50C to 600C.   2. The method for oxidizing or decomposing organic matter according to claim 1, wherein the photocatalyst particles are obtained by granulating photocatalyst fine particles with an adhesive.