JP2005205312A - Decomposition catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that the treatment of plastics is a big problem and there is a method for decomposing plastics by using a decomposition catalyst and heat or light as an energy source, namely, mixing plastic fragments with powder of the catalyst to decompose plastics comparatively more easily however this method has such a weak point that the catalyst soars and goes to the outside together with decomposed products when the catalyst is made smaller to increase the surface area in consideration of the catalyst efficiency and even if the catalyst efficiency is made excellent, there is no guarantee that the decomposition efficiency of the catalyst is made excellent as a whole. <P>SOLUTION: This decomposition catalyst has such a particle size distribution that particles having ≥1.2 mm particle size are in the range of 1-50 wt.%, particles having 0.5-1.2 mm particle size are in the range of 40-90 wt.% and particles having ≤0.5 mm are in the range of 1-20 wt.%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cracking catalyst.

  The decomposition catalyst is a catalyst for decomposing a compound, particularly an organic substance, and may be a thermal decomposition catalyst, an oxidative decomposition catalyst, a photocatalyst, or the like. The material of the catalyst itself may be metal, metal oxide, ceramic, or any other material.

  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 has been pointed out that combustion ash remains and toxic components remain therein.

  There is also a method in which plastic is decomposed with a decomposition catalyst using heat or light as an energy source. In this method, plastic fragments are mixed with catalyst powder, and the plastic can be decomposed relatively easily.

However, in this method, from the viewpoint of catalyst efficiency, the smaller the catalyst and the larger the surface area, the better. However, when the catalyst is simply small, it has a drawback that it rises and is entrained by the decomposition product and goes out of the system. It was also found that the catalyst efficiency is good, but the overall decomposition efficiency is not always good.
That is, conventionally, the catalyst is almost single and all have the same size, and the size is conventionally adjusted by a sieve or the like. This was counterproductive.

  Therefore, a catalyst having a high decomposition efficiency as a whole substance is provided.

In view of the current situation as described above, the present inventors have completed the catalyst of the present invention as a result of intensive research, and the feature thereof is a cracking catalyst, and its particle size distribution falls within the following range. is there.
1.2 mm or more is 1 to 50% by weight,
0.5-1.2mm is 40-90% by weight
0.5 mm or less is 1 to 20% by weight.

  The present inventors paid attention to the fact that the catalyst is often used with mixing and stirring, and completed it by studying various factors other than the catalytic effect such as stirring efficiency and physical decomposition of the substance to be decomposed by the catalyst itself. It was.

  The substance to be decomposed is usually an organic substance. For example, plastic, rubber, plant and the like. Of course, these are related to a catalyst that can be decomposed, and any catalyst that can be decomposed may be used.

First, the particle size distribution of the catalyst is important. As a result of considering not only the catalyst efficiency but also various physical factors, it was found that the range described in claim 1 is optimal.
Here, the catalyst assists the decomposition of the compound, and may be a thermal decomposition catalyst, a photodecomposition catalyst, or other various decomposition catalysts. As described above, any material such as titanium oxide may be used.

  Here, the catalyst size may be the size of the catalyst itself, granulated catalyst powder, or pulverized again. The shape may be spherical or any pulverized shape.

  As a granulation method, any method may be used as long as the powder is fixed by a binder, sintered, or other powder is collected and enlarged. In particular, in a method using a binder, a method of fixing with the same kind of binder as the catalyst is suitable. For example, when the catalyst powder is titanium oxide, titanium alkoxide is used as the binder.

  The basis of the particle size distribution of the present invention is to use roughly three types of size particles. The large size is 1.2 mm or more, the medium size is 0.5 to 1.2 mm, and the small size is 0.5 mm or less. Here, the size is represented by the diameter of a sphere as a representative, but in the case of an irregular shape, it is the maximum length.

  First, the thickness of 1.2 mm or more is 1 to 50% by weight, but 7 to 12% by weight is preferable. This is because the large particles of 1.2 mm or more are agitated, whereby the object to be decomposed is physically decomposed or the agitation efficiency is increased. However, if the amount is too large, the surface area becomes small and the catalyst efficiency decreases.

  The thing of 0.5-1.2 mm is 40 to 90 weight%. This occupies the main body as a catalyst. The thing of this size maintains the efficiency as a catalyst by existing most. If this is too small, it will be too coarse and the efficiency will be reduced, or it will be too fine and it will rise or it will be inconvenient to handle.

  Finally, 0.5 mm or less is 1 to 20% by weight. This is because a small one is also required, so that even when the object to be decomposed becomes small, it can be contacted efficiently, and a sufficient surface area can be secured. This too. 7 to 12% by weight is preferred.

The above particle size distribution may be further finely divided and more strictly classified. For example, it may be divided as follows.
1.6 mm or more, 0.1 to 2.0% by weight,
1.2 to 1.6 mm is 5 to 15% by weight,
0.7 to 1.0 mm is 20 to 40% by weight,
0.5 to 0.7 mm is 30 to 50% by weight,
0.5 mm or less is 1 to 15% by weight.

  It may be divided more finely in this way. This is because experiments have shown that it is better to have various sizes.

  Furthermore, the catalyst of the present invention is not limited to the catalyst itself or a granulated catalyst powder, but may be a catalyst powder supported on another carrier.

The carrier may be any particles such as silica sand. The size is such that it fits the above size.
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. Further, in the case of a titanium oxide catalyst, it is considered that the catalyst efficiency is improved as a whole when titanium alkoxide is used as an adhesive as described above. The same applies when crushing.

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 a carrier, and then cement and a catalyst are fixed. First, the cement or catalyst is fixed by the initial adhesive strength of the water-based resin. And if a cement hardens | cures, even if a water-system resin is decomposed | disassembled by the oxidizing power etc. by a catalyst, it will be hold | maintained by the cement.

The method of using the catalyst of the present invention is free and may be used in the same manner as conventional catalysts. However, a child used by mixing and stirring with a substance to be decomposed is suitable, and is the most effective method.
The temperature of the thermal catalyst, such as heating, pressure, presence / absence of electromagnetic wave irradiation, and pH in the liquid can be freely determined.

The catalyst of the present invention has the following great advantages.
(1) Since the catalyst has a single size and a specific particle size distribution, the decomposition efficiency is very good.
(2) If a powder granulated powder is used, various sizes can be produced freely, and the implementation is easy.
(3) With the catalyst having the particle size distribution of the present invention, defects such as soaring and entrainment can be reduced.

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

Example 1
Here, a granulated titanium oxide (anatase-type photocatalyst) powder (size of several nm to several tens of nm) was used as the catalyst. The granulation method was here the sintering method. The particle size distribution is as follows.
1.6mm or more, 0.98% by weight,
1.2 to 1.6 mm is 10.0% by weight,
0.7 to 1.2 mm is 34.3% by weight,
0.5 to 0.7 mm is 41.9% by weight,
0.3 to 0.5 mm is 9.87% by weight.
Less than 0.3 mm is 2.95% by weight.

Example 2
The same catalyst as in Example 1 was used. The particle size distribution is as follows.
1.6 mm or more, 22.2% by weight,
1.2 to 1.6 mm is 21.4% by weight,
0.7 to 1.2 mm is 25.8% by weight,
0.5 to 0.7 mm is 22.7% by weight,
0.3 to 0.5 mm is 7.3% by weight.
Less than 0.3 mm is 0.6% by weight.

Comparative Example 1
The same catalyst with a uniform size of 0.1 to 0.3 mm was used as a comparative example.

FIG. 1 is a simple apparatus for examining the decomposition efficiency of a catalyst. A 500 cc beaker 1 is provided with a stirring device 2 and a heating device 3. Here, electromagnetic waves may or may not be irradiated. It has been found through experiments by the inventors that a photocatalyst exhibits a catalytic effect when heated even without electromagnetic waves.
The plastic piece 4 (about 5 mm of crushed polyethylene) and the catalyst were introduced into this apparatus in substantially the same amount (50 g) and mixed by heating (about 400 ° C.) to measure the time for the plastic to decompose and become gas.

  In the comparative example, it took about 30 minutes for the plastic piece to disappear. A considerable amount of catalyst flew up and dissipated into the air. In Example 1 of the present invention, it almost disappeared in 15 minutes and there was little soaring. Moreover, in Example 2, it almost disappeared in 13 minutes. Furthermore, although it performed only with the powder smaller than a comparative example, it rose so much that it could not be continued.

It is a schematic sectional drawing which shows one example of the apparatus which investigates the effect of this invention catalyst.

Explanation of symbols

1 Beaker 2 Stirrer 3 Heater 4 Plastic Piece 5 Catalyst

Claims (4)

A granular catalyst characterized in that it is a decomposition catalyst and its particle size distribution falls within the following range.
1.2 mm or more is 1 to 50% by weight,
0.5-1.2mm is 40-90% by weight
0.5 mm or less is 1 to 20% by weight.   The cracking catalyst according to claim 1, wherein the catalyst is obtained by granulating fine powder.   The cracking catalyst according to claim 1 or 2, wherein the catalyst is a photocatalyst. The decomposition catalyst according to claim 2 or 3, wherein the granulation is a sintering method or an adhesion method.

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