JP2002085974A - Iron hydroxide-containing combustion catalyst, manufacturing method thereof and thermoplastic resin molding containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an iron hydroxide-containing combustion catalyst having sufficient catalytic activity as a combustion catalyst and hardly causing the change in color even when temperature rises when blended with a thermoplastic resin or molded and a molding free from product defects such as color unevenness or foaming even when the iron hydroxide-containing combustion catalyst is incorporated in the thermoplastic resin. SOLUTION: The iron hydroxide-containing combustion catalyst is composed of iron hydroxide-containing particle having an acicular form or fusiform and containing 0.1-1.0 wt.% sulfur based on sulfate radical in the particle surface or in the vicinity of the particle surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron-oxide-containing combustion catalyst having sufficient catalytic activity as a combustion catalyst and having an increased phase transition temperature accompanied by dehydration, a method for producing the same, and the iron-oxide-containing iron-oxide combustion catalyst. The present invention relates to a thermoplastic resin molded article containing:

[0002]

2. Description of the Related Art In recent years, changes in lifestyles, improvement in living standards and income levels have resulted in the overflow of new products and the formation of a rich material culture. The number of plastic products in waste has been increasing rapidly. Such plastic waste is usually landfilled or incinerated, but there is a shortage of landfills for landfill. Also, in the case of incineration, incomplete combustion due to local lack of oxygen in the incinerator produces a large amount of dioxins and the combustion calorie is extremely high. There were problems such as damage to the incinerator as a cause.

As a method for solving such a problem, a method of supplying complete air to a portion of a reburning chamber of an incinerator to promote complete combustion, a method of burning the inside of the furnace by spraying water or the like to keep the temperature within a certain temperature or less. To prevent damage to the incinerator. In addition, recently, by incorporating spindle-shaped hydrous ferric oxide particles and granular magnetite particles having a combustion promoting action into a thermoplastic resin, it is possible to improve combustion efficiency at the time of incineration and to reduce residual ash after incineration. A garbage bag has been proposed (Japanese Patent No. 282).
No. 4203). This method does not require a special incineration facility, and the hydrous iron oxide particles and magnetite particles used are safe and non-toxic, and are excellent from the viewpoint of public health, hygiene, safety and environmental pollution prevention. Is the way.

[0004] However, the iron oxide hydroxide particles contain Fe ₂ O.
_As shown by the chemical formula of ₃ · nH ₂ O, it has water of crystallization, and generally when heated to about 200 to 270 ° C., dehydration occurs and phase transition to red-brown hematite (α-Fe ₂ O ₃ ) occurs. . Therefore, when using a thermoplastic resin that needs to be molded at or above the phase transition temperature accompanied by dehydration, or when the processing temperature rises due to shear heat insulation, such as when extruded at a high speed, during the molding process There has been a problem in that dehydration occurs and the hue of the product varies widely, and foaming causes product failure.

On the other hand, various attempts have conventionally been made to improve the heat resistance of hydrous iron oxide particles in order to prevent a change in hue when the hydrous iron oxide particles are used as a coloring agent. Hydrothermal treatment of hydrous iron oxide particles in water or an aqueous alkali solution using an autoclave (Japanese Patent Publication No. 53-28158, etc.), coating the surface of the hydrous iron oxide particles with an aluminum compound, a silicon compound, etc. , A solid solution method (Japanese Patent Publication No. 6-1723)
No. 7, Japanese Patent Publication No. 7), after treating the hydrous iron oxide particles with an alkaline aqueous solution and an acidic aqueous solution, the composite hydrous oxide of Fe and Al and A
(1) A method of coating a hydroxide (JP-A-11-12492) and the like are known. However, these methods have a problem that although the heat resistance is improved and the temperature at which phase transition accompanied by dehydration occurs is increased, the catalytic activity as a combustion catalyst is rather reduced.

[0006]

DISCLOSURE OF THE INVENTION The present invention has sufficient catalytic activity as a combustion catalyst even though it contains sulfur, and is useful when compounded with a thermoplastic resin or molded. It is an object of the present invention to provide a molded article free from product defects such as uneven color and foaming even when the iron-oxide-containing combustion catalyst and the thermoplastic resin contain the iron-oxide-containing combustion catalyst, which hardly causes a change in hue even at a high temperature. Technical issues.

[0007]

The above technical objects can be achieved by the present invention as described below. That is, the present invention provides: (1) an iron-containing hydrated iron oxide comprising needle-like or spindle-shaped hydrated iron-containing particles having a sulfur content based on a sulfate group of 0.1 to 1.0 wt% at or near the particle surface. Combustion catalyst. (2) The catalyst for combustion of hydrated iron oxide according to (1), which has a catalytic activity capable of oxidizing 50% or more of methane when measured under the following conditions. <Test conditions> 1. 1. Test method Test apparatus: normal pressure fixed bed flow type reaction apparatus Reaction temperature: 550 ° C., SV = 12800 h ⁻¹ , measurement of change rate after 1 hour passage 2. 2. Hydrous iron oxide combustion catalyst Catalyst amount: 0.5 g Source gas Oxygen partial pressure is 20.3 kPa, methane partial pressure is 3.4 kPa
(3) treating needle-like or spindle-shaped hydrous iron oxide particles in an acidic aqueous solution of sulfuric acid or sulfate (1)
Or the method for producing a catalyst for combustion of hydrated iron oxide according to (2). (4) A thermoplastic resin molded article characterized by containing 0.1 to 20.0% by weight of the combustion catalyst containing iron oxide hydroxide according to (1) or (2).

Hereinafter, the present invention will be described specifically. First, the iron-containing oxyhydroxide combustion catalyst according to the present invention, goethite,
It is composed of one or more of iron oxide-containing particles such as akagenite and lepidocrocite. Further, the particle shape may be acicular or spindle-shaped, but in particular, spindle-shaped having an appearance (bamboo leaf shape) in which a number of ultrafine fibers are bundled is preferable. Further, the content of sulfur based on the sulfate group on the surface or in the vicinity of the surface of the particles is 0.1 to 1.0 wt%. Preferably 0.2 to
0.8 wt%, more preferably 0.2 to 0.6 wt%. When the content of sulfur based on the sulfate group present on the surface or in the vicinity of the surface of the iron oxide hydroxide particles exceeds 1.0 wt%, the sulfate group acts as a catalyst poison, and the catalytic activity as a combustion catalyst rapidly decreases. And a sufficient combustion promoting effect cannot be obtained. If it is less than 0.1 wt%, sufficient heat resistance cannot be obtained. The dehydration start temperature is affected not only by the specific surface area of the hydrous iron oxide particles used as a raw material, but also by the sulfur content based on the sulfate group existing on or near the surface. That is, when the BET specific surface area of the hydrous iron oxide particles used as the raw material is 5 to 50 m ² / g, the dehydration start temperature is 230
To 270 ° C., whereas the dehydration start temperature of the iron-containing oxyhydroxide combustion catalyst according to the present invention having the same BET specific surface area value is preferably 240 to 310 ° C., more preferably 245 to 310 ° C., More preferably, 250 ° C. to 31
0 ° C and 10-40 ° C higher. The BET specific surface area value of the hydrous iron oxide particles used as a raw material is 50 to 160 m ² / g
In the case of the dehydration start temperature is 200 to 230 ° C., the dehydration start temperature of the iron oxide hydroxide combustion catalyst according to the present invention having the same BET specific surface area value is preferably 21 1
0 to 270 ° C, more preferably 215 to 270 ° C, and still more preferably 220 to 270 ° C, is 10 to 40 ° C higher.

Incidentally, the iron oxide hydroxide particles generally contain sulfur as an impurity derived from iron sulfate or the like as an iron raw material inside the particles, and there is a problem that a large amount of the sulfur lowers the catalytic activity. However, the sulfur content as this impurity is
As shown in the following Examples and Comparative Examples, it is present in the whole particles including the inside of the particles, and is based on the sulfate group present on the surface or near the surface of the iron oxide-containing particles in the iron oxide-containing catalyst of the present invention. Sulfur is completely different in its effect and action.

[0010] The catalyst for burning iron oxide hydroxide according to the present invention preferably has a major axis diameter of 0.05 to 2.0 µm, more preferably 0.1 to 1.0 µm. 2.0μ long shaft diameter
When it is more than m, it is difficult to obtain sufficient catalytic activity as a combustion catalyst, and when it is less than 0.05 μm, kneadability with a thermoplastic resin is poor. BET specific surface area value is 5 to 160 m ²
/ G is preferable, and more preferably 5 to 120 m ² / g,
Still more preferably, it is 5 to 100 m ² / g. BE
When the T specific surface area value is less than 5 m ² / g, it is difficult to obtain a sufficient catalytic activity as a combustion catalyst, and when it exceeds 160 m ² / g, the kneading property with the thermoplastic resin is deteriorated.

Although the above-mentioned constitution is an essential requirement of the combustion catalyst containing hydrated iron oxide according to the present invention, it is preferable that the combustion catalyst has excellent catalytic activity. The catalytic activity as a combustion catalyst can be represented by a methane change rate in a methane oxidation reaction. When measured under the following conditions, the hydrated iron oxide combustion catalyst according to the present invention has a methane change rate of 50% or more, preferably It is at least 60%, more preferably at least 70%. In particular, the spindle-shaped hydrated iron oxide combustion catalyst according to the present invention has more excellent catalytic activity, and preferably has a methane change rate of 60% or more, more preferably 70% or more,
It is even more preferably 80% or more. <Test conditions> 1. 1. Test method Test apparatus: Atmospheric pressure fixed bed flow type reaction apparatus Reaction temperature: 550 ° C., SV = 12800 h ⁻¹ , change rate after 1 hour passage is measured 2. Hydrous iron oxide combustion catalyst Catalyst amount: 0.5 g Source gas Oxygen partial pressure is 20.3 kPa, methane partial pressure is 3.4 kPa
If the rate of change of methane oxidation is less than 50%, a sufficient combustion promoting effect cannot be obtained because the catalytic activity as a combustion catalyst is low.

[0012] Such an iron oxide-containing combustion catalyst can be produced as follows. First, in the present invention, needle-like or spindle-like hydrous iron oxide particles are used. Needle-shaped or spindle-shaped iron oxide-containing particles are present, for example, in the presence of an additive in a suspension containing a neutralization precipitate of an aqueous ferrous salt solution and an aqueous alkali solution such as an aqueous alkali hydroxide solution and an aqueous alkali carbonate solution. It can be produced from an aqueous solution by passing an oxygen-containing gas such as air under or in the absence thereof, and it can be produced by filtering, washing and drying by a conventional method. In addition, the content of sulfur contained as impurities derived from iron sulfate or the like which is an iron raw material of the iron oxide hydroxide particles used in the present invention is preferably 0.6 wt% or less, more preferably 0.4 wt% or less, Even more preferably 0.3 wt
% Or less. It is not preferable to use the iron oxide hydroxide particles having a sulfur content exceeding 0.6 wt%, because the catalytic activity of the obtained iron oxide hydroxide combustion catalyst as a combustion catalyst is insufficient.

Next, the above-mentioned hydrated iron oxide particles are treated in an acidic aqueous solution of sulfuric acid or sulfate. As a treatment method, for example, the hydrated iron oxide particles are immersed in an acidic aqueous solution of sulfuric acid or sulfate for a certain period of time. A method of immersing, followed by filtering and drying iron-containing iron oxide particles suspended in the liquid by a conventional method is used. Further, in order to adjust the sulfur content on the particle surface or in the vicinity of the particle surface, if necessary, washing may be performed after filtration. In addition, in order to improve the dispersibility in a thermoplastic resin, the surface of the particles of the combustion catalyst containing hydrous iron oxide according to the present invention can be treated with various surface treating agents.

As the acidic aqueous solution of sulfuric acid or sulfate used at this time, not only an aqueous solution of sulfuric acid, sulfurous acid and the like, but also an aqueous solution of sulfate such as ammonium sulfate which becomes acidic when converted into an aqueous solution can be used. Further, the pH value at the time of the treatment with the acidic aqueous solution is preferably set to 4 or less, more preferably 3.5 or less. When the pH value exceeds 4, the effect of the acidic aqueous solution treatment cannot be obtained. Further, there is no point in adding sulfuric acid and sulfate more than necessary, and in consideration of economy, the lower limit is about 0.1 as the pH value. Preferred acidic aqueous solutions include 0.001-2N aqueous solutions of sulfuric acid.

Further, the concentration of the iron oxide hydroxide particles to be introduced into the acidic aqueous solution for treating the above iron oxide hydroxide particles is preferably 1 to 300 g / L, and 10 to 2 g / L.
More preferably, it is 00 g / L. When the amount is less than 1 g / L, the processing amount of the processing unit is too small, so that it is not industrial. When it exceeds 300 g / L, it is difficult to perform a uniform treatment. Further, the treatment temperature is preferably from 10 to 100 ° C, more preferably from 20 to 80 ° C, and still more preferably from 20 to 70 ° C. When the temperature is lower than 10 ° C., it takes an extremely long time to obtain the effect of the treatment, which is industrially disadvantageous. If the temperature exceeds 100 ° C., an apparatus such as an autoclave is required, which is not industrially preferable. The treatment time is usually preferably at least 15 minutes, more preferably at least 20 minutes. It is meaningless to perform the treatment for a longer time than necessary, and the upper limit is about 360 minutes in consideration of economy.

Next, the thermoplastic resin molded article according to the present invention will be described. The thermoplastic resin can be used without particular limitation as long as it can be processed by ordinary extrusion molding, injection molding, press molding, etc., for example, low-density polyethylene, linear low-density polyethylene, and high-density polyethylene. And polyolefin resins such as copolymers of ethylene and other polymerizable monomers such as (meth) acrylate and vinyl acetate, and polyolefin resins such as polypropylene resins, polyamide resins, polyester resins, and the like. . Among them, polyolefin-based resins can be suitably used, and in particular, when a thermoplastic resin requiring a high molding processing temperature among polyolefin-based resins such as high-density polyethylene and polypropylene is used.

The thermoplastic resin molded article according to the present invention is obtained by mixing the above-mentioned thermoplastic resin with an iron hydroxide-containing combustion catalyst or a masterbatch comprising an iron oxide hydroxide-containing combustion catalyst and a thermoplastic resin and supplying the mixture to an extruder or the like. Then, after melt-kneading, it can be manufactured by molding into a predetermined shape with a required molding machine. At this time, the hydrous iron oxide combustion catalyst according to the present invention has a higher phase transition temperature accompanied by dehydration, and therefore, conventionally, a case where a thermoplastic resin which is easily discolored when hydrous iron oxide particles are blended is used. Even if it does, the thermoplastic resin molded article can be manufactured without discoloration or foaming. In addition, the content of the hydrous iron oxide combustion catalyst in the thermoplastic resin molded body is 0.1 to 20.0 wt%, preferably 0.5 to 10.0 wt%, more preferably 1.0 to 8.0 wt%.
0 wt%. The content of the hydrous iron oxide combustion catalyst is 0.1
If it is less than wt%, the effect of promoting combustion is insufficient.
If the content exceeds 0.0% by weight, the effect of promoting the combustion cannot be exhibited in proportion to the content, and instead, it causes a decrease in mechanical strength, an increase in cost, or a decrease in molding workability, which is not preferable. Further, the thermoplastic resin molded article according to the present invention may be appropriately blended with various additives such as a conventionally known lubricant, an antiblocking agent, an antioxidant, a weathering agent, a coloring agent, etc. Can be used in combination.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of the present invention is as follows. The catalytic activity of the hydrous iron oxide combustion catalyst as a combustion catalyst was evaluated by measuring the rate of change of methane in the methane oxidation reaction using a normal-pressure fixed-bed flow reactor 1 shown in FIGS. 1 (A) and 1 (B). . The reaction tube 2 of the present reaction apparatus 1 is made of quartz. The central portion is a tube having an inner diameter of 9 mm, a length of 30 mm, and both ends of the tube having an inner diameter of 4 mm. The total length is 250 mm. In the central part of the reaction tube 2, the catalyst containing hydrated iron oxide according to the present invention 21 sized to 10 to 20 mesh as a catalyst
Was filled, and both ends were fixed with quartz wool 22.
Next, the reaction tube 2 filled with the catalyst was inserted into a tubular electric furnace 3 controlled at 550 ° C., and was held in helium gas for 20 minutes, after which the oxygen partial pressure was 20.3 kPa and the methane partial pressure was 3. A source gas diluted with helium gas to 4 kPa is introduced into the reaction system to start the reaction, and an online gas chromatograph (manufactured by Shimadzu Corporation: GC-8APT) equipped with a thermal conductivity type detector and an integrator (Shimadzu) The product after passing the raw material gas through the column for 1 hour was sampled by using Manufacturer: C-R6A) to measure the number of moles of methane and carbon dioxide, and the methane change rate was calculated according to the following formula. . Methane change rate (%) = (1-CH ₄ / (CH ₄ + C)
O ₂ )) × 100 Helium was used as a carrier gas for the gas chromatograph, and Molecular Sieve was used as a column.
5A (20cm × 3mm) and PorapacN (6mx
3mm), the former is used to detect methane,
The latter was used for the detection of carbon dioxide. In this case, S
V was 12,800 h- ¹ . Here, SV is S
This refers to a space velocity, which is an amount obtained by dividing a flow rate of a reaction gas by a volume of a catalyst, and is a unit (h) of a reciprocal of time.
^-1 ).

The dehydration start temperature of the combustion catalyst containing hydrous iron oxide is determined by thermogravimetric analysis (TGA) using a thermogravimetric simultaneous measuring device (DTG-40 manufactured by Shimadzu Corporation) at a heating rate of 10 ° C./min from room temperature to 800 ° C. Draw a tangent to each of the two curves corresponding to the plateau region and the region where the rapid weight loss occurs before starting the rapid weight loss, read the temperature corresponding to the intersection of both tangent lines, and start dehydration. Temperature. The presence or absence of sulfur based on the sulfate group on the particle surface or in the vicinity of the particle surface of the hydrated iron oxide combustion catalyst is determined by X-ray photoelectron spectroscopy (XPS) using an X-ray photoelectron spectrometer (ESCA-1000 manufactured by Shimadzu Corporation). ), The peak of sulfur (2p orbit) existing near the surface (around 169 eV),
Peak of oxygen (1s orbital) in sulfate group (531.9e
V) was measured and confirmed. Further, the content of sulfur based on the sulfate group in the surface of the particle or in the vicinity of the particle surface is determined by a carbon-sulfur analyzer (HORIBA, Ltd .: EMIA-2200).
(Type), the sulfur content of the hydrous iron oxide particles before and after the treatment with the acidic aqueous solution of sulfuric acid or sulfate was measured, and the difference was shown. The average particle diameter of the hydrous iron oxide combustion catalyst was indicated by the average value of numerical values measured from an electron micrograph. The BET specific surface area of the hydrous iron oxide combustion catalyst was indicated by a value measured by the BET method.

[0020]

The most important point in the present invention is that the hydrous iron oxide particles are needle-like or spindle-shaped, and have a sulfur content of 0.1 to 1.0 wt% at or near the particle surface. The fact is that iron combustion catalysts have sufficient catalytic activity as combustion catalysts and have a higher phase transition temperature with dehydration than conventionally known hydrous iron oxide particles.

The present inventor considers this fact as follows. First, the combustion mechanism when the hydrated iron oxide particles act as a combustion catalyst is as follows. First, the hydrated iron oxide combustion catalyst is dehydrated by heating in the combustion process to form hematite, and oxygen atoms on the hematite surface react with organic substances to oxidize. The reaction proceeds. At this time, the surface of the hematite simultaneously changes its structure into magnetite, but it is considered that the reaction of magnetite replenishing oxygen from the atmosphere and changing its structure again into hematite is repeated. The reason why the hydrous iron oxide combustion catalyst according to the present invention can exhibit a sufficient catalytic activity as a combustion catalyst even though it contains a sulfur component based on a sulfate group is determined by thermogravimetric analysis (TG
As can be inferred from the fact that the mass loss occurs at around 500 ° C. in A), at a high temperature of 500 ° C. or more, the sulfur content based on the sulfate group existing on or near the surface of the iron oxide-containing particles becomes oxidized. This is considered to be due to vaporization as sulfur (SOx) or the like. Therefore, the catalyst containing iron oxide hydroxide according to the present invention has insufficient catalytic activity as a combustion catalyst at a low temperature of less than 500 ° C. because sulfur based on a sulfate group becomes a catalyst poison, but is generally performed at 800 ° C. or more. At the time of incineration, it has sufficient catalytic activity as a combustion catalyst. On the other hand, the sulfur contained as an impurity in the hydrated iron oxide derived from the iron raw material such as iron sulfate replaces oxygen and sulfur in the hydrated iron oxide particles, and furthermore does not vaporize even at a high temperature of 500 ° C. or more. If it exceeds 0.6 wt%, the catalytic activity is significantly reduced.

The reason why the phase transition temperature accompanying dehydration of the hydrated iron oxide combustion catalyst according to the present invention is increased is that the sulfate group existing on the surface or near the surface of the hydrated iron oxide particles causes the movement of iron atoms in the crystal. It is thought to suppress water molecules and make it difficult to emit water molecules.

[0023]

The present invention will be described below with reference to examples and comparative examples. Example 1 BET specific surface area: 85 m ² / g, average major axis diameter: 0.25 μm
m, 5 g of spindle-shaped goethite particles having a sulfur content of 0.05 wt% as impurities were suspended in a 0.05 N aqueous sulfuric acid solution to adjust to a suspension having a pH of 1.7 and a concentration of 50 g / L. The suspension was treated with sulfuric acid at 50 ° C. for 30 minutes while stirring, and the precipitate obtained by suction filtration was concentrated in air for 50 minutes.
Drying at 0 ° C. yielded an iron oxide-containing combustion catalyst. The resulting hydrous iron oxide combustion catalyst had a BET specific surface area of 68 m ² / g, an average major axis diameter of 0.25 μm, and was measured by XPS.
It was confirmed that sulfur based on the sulfate group was present on the particle surface or near the particle surface of the hydrated iron oxide combustion catalyst, and as a result of measurement using a carbon-sulfur analyzer, the particle surface or near the particle surface of the hydrated iron oxide combustion catalyst was determined. Is 0.38
wt%. The dehydration start temperature of the obtained hydrated iron oxide combustion catalyst was 245 ° C., which was higher than that of the hydrated iron oxide combustion catalyst of Comparative Example 1 described later, and the phase transition to hematite was suppressed. (See (X-1) in FIG. 2). Further, the methane change rate in the methane oxidation reaction at 550 ° C. was 95%, indicating a sufficient catalytic activity as a combustion catalyst.

Further, the combustion catalyst containing hydrated iron oxide having a melting point of 13
5% blended in 5% high density polyethylene at 50 ° C
m, die diameter 125mm, lip opening 1mm, cylinder temperature 200 ° C, die temperature 200 ° C, discharge rate 80kg /
When molded under the conditions of h, no discoloration was observed even though the resin temperature rose to 230 ° C. due to the occurrence of shear insulation, and a polyethylene film colored yellow originally containing hydrous iron oxide was obtained. Also, this molded body burns in a short time,
No smoke was generated during combustion. In addition, it was found that there was little unburned residue in the residue at the end of combustion, and complete combustion was achieved.

Comparative Example 1 Before the sulfuric acid treatment described in Example 1, the sulfuric acid-containing combustion catalyst particles contained 0.05 wt% of sulfur as an impurity. Was confirmed by XPS. Although the methane change rate in the methane oxidation reaction was 95%, indicating sufficient catalytic activity as a combustion catalyst, the dehydration start temperature was 212 ° C., which was lower than the dehydration start temperature of the hydrated iron oxide combustion catalyst described in Example 1 above. The temperature was 33 ° C. lower than that. (See (X-2) in FIG. 2). Further, 5% of the high-density polyethylene having a melting point of 135 ° C. was blended with this iron-oxide-containing combustion catalyst under the same conditions as in Example 1 to form a mixture. The desired color was not obtained.

Example 2 BET specific surface area 17 m ² / g, average major axis diameter 0.80 μm
m, 10 g of acicular goethite particles having an impurity sulfur content of 0.28 wt% were suspended in a 1N aqueous sulfuric acid solution to adjust the suspension to a pH of 0.45 and a concentration of 100 g / L. The resulting suspension was subjected to sulfuric acid treatment at 30 ° C. for 20 minutes while stirring, and the precipitate obtained by suction filtration was dried at 50 ° C. in air.
To obtain an iron oxide hydroxide-containing combustion catalyst of the present invention. The resulting hydrous iron oxide combustion catalyst had a BET specific surface area of 8.0 m ² /
g, the average major axis diameter was 0.80 μm, and as a result of measurement by X-ray photoelectron spectroscopy (XPS), it was confirmed that sulfur based on a sulfate group was present at or near the particle surface of the iron oxide hydroxide-containing combustion catalyst. As a result of measurement using a carbon-sulfur analyzer (HORIBA, Ltd .: EMIA-2200), the sulfur content of the iron oxide hydroxide-containing combustion catalyst at the particle surface or in the vicinity of the particle surface was 0.43 wt%. Was. The dehydration start temperature of the obtained hydrated iron oxide combustion catalyst was 290 ° C., which was higher than that of the hydrated iron oxide combustion catalyst of Comparative Example 2 described later, and the phase transition to hematite was suppressed. (See (Y-1) in FIG. 3). Further, the methane change rate in the methane oxidation reaction at 550 ° C. was 82%, indicating a sufficient catalytic activity as a combustion catalyst.

Further, the combustion catalyst containing iron oxide hydroxide was melted at a melting point of 21.
5% blended with 6-66 copolymer nylon at 8 ° C and caliber 50
mm, die diameter 125mm, lip opening 1mm, cylinder temperature 260 ° C, die temperature 260 ° C, discharge amount 60kg
When molded at / h, the resin temperature was 270 ° C., but no foaming or discoloration due to dehydration was observed. Further, the molded body burned in a short time, and no smoke was generated during the burning. In addition, it was found that there was little unburned residue in the residue at the end of combustion, and complete combustion was achieved.

COMPARATIVE EXAMPLE 2 Before the sulfuric acid treatment described in Example 2, the catalyst particles containing hydrous iron oxide contained 0.28% by weight of sulfur as an impurity. Was confirmed by XPS. The methane change rate in the methane oxidation reaction was 83%, indicating a sufficient catalytic activity as a combustion catalyst. However, the dehydration start temperature was 263 ° C., which was lower than the dehydration start temperature of the hydrous iron oxide combustion catalyst described in Example 2 above. It was 27 ° C lower than that. (See (Y-2) in FIG. 3).
Further, 5% of this iron-containing oxyhydroxide combustion catalyst was mixed with 6-66 copolymer nylon having a melting point of 218 ° C. under the same conditions as in Example 2, and the mixture was molded. It was discolored and the desired color was not obtained.

Comparative Example 3 BET specific surface area 20 m ² / g, average major axis diameter 0.78 μm
m, the sulfur content of impurities is 0.65 wt%,
According to the XPS, the dehydration start temperature of the needle-like hydrated iron oxide combustion catalyst particles in which no sulfur was present on the particle surface or in the vicinity of the particle surface was 262 ° C. Further, the rate of change of methane in the methane oxidation reaction at 550 ° C. was 45%, and the catalytic activity was poor. Further, when the above-mentioned catalyst containing oxidized iron oxide was mixed with 6-66 copolymer nylon having a melting point of 218 ° C. and kneaded, the color changed slightly to red.

[0030]

The hydrous iron oxide combustion catalyst according to the present invention has a sufficient catalytic activity as a combustion catalyst, and has a high phase transition temperature accompanied by dehydration. Even when the temperature is high, the color change is unlikely to occur, and the resulting thermoplastic resin molded product has a high burning speed due to the action of the hydrous iron oxide combustion catalyst as a combustion catalyst during incineration treatment, and is easily burned completely, thereby producing dioxins. Can also be suppressed.

[Brief description of the drawings]

FIG. 1 is an overall conceptual diagram (A) of an ordinary-pressure fixed-bed flow reactor, and an enlarged view (B) of a reaction tube portion thereof.

FIG. 2 shows a catalyst (X-1) containing iron oxide hydroxide of the present invention according to Example 1 and particles of iron oxide hydroxide (X) before treatment in Comparative Example 1.
4 is a chart showing the result of thermogravimetric analysis (TGA) in an air stream of -2).

FIG. 3 shows a catalyst (Y-1) containing hydrated iron oxide of the present invention according to Example 2 and particles of hydrated iron oxide (Y) before treatment in Comparative Example 2;
4 is a chart showing the result of thermogravimetric analysis (TGA) in an air stream of -2).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Atmospheric pressure fixed bed flow type reaction apparatus 2 Reaction tube 21 Catalyst 22 Quartz wool 3 Tubular electric furnace

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Suminori Tanaka 1515 Nakatsu-cho, Marugame City, Kagawa Prefecture Inside Okura Industry Co., Ltd. (72) Tomoyuki Imai 1-4-1, Meiji Shinkai, Otake City, Hiroshima Prefecture Toda Kogyo Co., Ltd. Inside the Otake Creative Center (72) Inventor Toshihiro Moriga 4-70-70 Sumiyoshi, Tokushima, Tokushima 602 Alpha States Sumiyoshi 602 (72) Inventor Ichiro Nakabayashi 2-29 Shinzocho, Tokushima, Tokushima F-term (reference) 4G069 AA14 BB04A BB04B BB10A BB10B BC66A BC66B BD08A CB07 CD01 DA05 EA02Y EA03Y EB18Y EC02Y EC22Y

Claims (4)

[Claims] An iron oxide-containing combustion catalyst comprising needle-like or spindle-shaped iron oxide-containing particles having a sulfur content based on a sulfate group of 0.1 to 1.0 wt% at or near the particle surface. 2. When measured under the following conditions, 5
The catalyst for combustion of hydrated iron oxide according to claim 1, which has a catalytic activity capable of oxidizing 0% or more. <Test conditions> 1. 1. Test method Test apparatus: normal pressure fixed bed flow type reaction apparatus Reaction temperature: 550 ° C., SV = 12800 h ⁻¹ , measurement of change rate after 1 hour passage 2. 2. Hydrous iron oxide combustion catalyst Catalyst amount: 0.5 g Source gas Oxygen partial pressure is 20.3 kPa, methane partial pressure is 3.4 kPa
Helium gas 3. The process for producing a catalyst for burning iron-containing hydroxide as claimed in claim 1, wherein the needle-shaped or spindle-shaped particles of the iron-containing hydroxide are treated in an acidic aqueous solution of sulfuric acid or sulfate. 4. A thermoplastic resin molded article containing 0.1 to 20.0 wt% of the catalyst for burning iron oxide hydroxide according to claim 1 or 2.