JPH1028875A - Carbonaceous hollow body catalyst, and its manufacture, and use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst having excellent adsorption and powerful oxidation capability, being capable of effectively removing and decomposing particularly organic compounds in waste water, and the manufacturing method, and use method thereof. SOLUTION: In the carbonaceous hollow body catalyst supporting a photocatalyst (e.g. metal oxide semiconductor including titanium oxide, zinc oxide, and iron oxide) on the surface of microsphere carbonaceous hollow body, the catalyst preferably can be used for adsorption-removing and decomposing organic compounds in water (particularly in waste water) because it has a large surface area and tend to buoy up on the water surface. The catalyst can be manufactured by rendering it to support the photocatalyst on the surface of the microsphere hollow body obtained by rapidly heating a carbonaceous material (powder coal or pitch) in the state of less oxygen content where incomplete combustion occurs, or by that the carbonaceous material is rendered to include tetra-valent titanium compounds including titanium isopropoxide or titanium tetrachloride as an aqueous solution and the like, and then it is rapidly heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a carbonaceous hollow body catalyst having a strong oxidizing power and particularly capable of efficiently removing and decomposing organic compounds in wastewater, and a method for producing and using the catalyst.

[0002]

2. Description of the Related Art It is well known that semiconductors have an oxidizing action as a photocatalyst. In order to carry out a photocatalytic reaction using this semiconductor, a method is generally employed in which fine semiconductor powder is suspended in a solution containing a substance to be oxidized, and this is irradiated with light.

[0003] In order to remove low-concentration organic compounds contained in wastewater, a method of adsorbing and removing the same using activated carbon has been used for a long time. A method utilizing photocatalysis of a semiconductor is also known. For example, there has been proposed a method for efficiently decomposing organic compounds (herbicides) contained in wastewater by using activated carbon carrying titanium oxide (TiO ₂ ) having a photocatalytic action (Chemistry Let).
ters (The Chemical Society)
of Japan), P.S. 1995-1998 (19
93)).

As described above, semiconductor photocatalysts are used to decompose organic compounds in wastewater because the concentration of organic compounds in the wastewater is low and the amount of treatment is enormous, in addition to the oxidizing power of the photocatalyst. Therefore, it is desirable to use sunlight as energy from the viewpoint of cost.

When a photocatalytic reaction is carried out in waste water, a method of suspending semiconductor powder in the waste water and irradiating the semiconductor powder with sunlight has been adopted.
Catalysts that tend to precipitate in the wastewater are not preferred. Further, since the depth to which sunlight can reach is limited, it is necessary to make the light-receiving area extremely large in order to irradiate the semiconductor powder which easily precipitates with sunlight to exert a catalytic action.

In the above-mentioned proposed method, the activated carbon has a true specific gravity of 1.6 to 2.1 and easily precipitates in wastewater, so that it is not easy to carry out treatments such as stirring and recovery. However, there is a problem that the light receiving area must be significantly increased as described above.

Further, although not an example in which wastewater is treated, JP-A-6-170220 discloses that a photocatalyst (metal oxide such as TiO ₂ , WO ₃ , Fe ₂ O ₃ ) is applied to the surface of activated carbon. A supported deodorant capable of maintaining a stable deodorizing effect for a long period of time is disclosed. This photocatalyst is
It exerts an excellent effect on the decomposition of organic compounds (odor components) in the gas phase. However, in the liquid phase the photocatalysts settle as in the proposed method above,
It cannot be applied to the decomposition of organic compounds contained in wastewater.

On the other hand, a floating titanium oxide photocatalyst in which a photocatalyst (TiO ₂ ) is supported on the surface of a hollow glass body having a diameter of about 100 μm has been developed (“Quarterly Chemical Review” No. 2).
3 (1994) "Catalytical Chemistry Involving Light", p. 129-1
32). Since the catalyst floats on water, it can utilize sunlight efficiently and is said to be suitable for decomposing floating organic compounds (for example, crude oil spilled to the sea).
However, since it is not possible to increase the specific surface area, which is important in the photocatalytic reaction, it is not possible to efficiently decompose the oxidized substance, and it has almost no adsorption capacity. It cannot be adsorbed or removed.

[0009]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in decomposing an organic compound in wastewater by using a semiconductor photocatalyst having an action of oxidatively decomposing an organic compound, and in particular, by using this photocatalyst. It is an object of the present invention to provide a photocatalyst which can be easily used, has high reaction efficiency, and can adsorb and remove organic compounds even under conditions without light irradiation, and a method for producing and using the same. .

[0010]

Means for Solving the Problems As a result of repeated studies to solve the above-mentioned problems, the present inventors have found that by using a fine spherical carbonaceous hollow body as a carrier for a photocatalyst,
It has been found that it is not necessary to remarkably increase the light receiving area when using sunlight, and it is possible to increase the specific surface area of the catalyst so that the decomposition reaction can be performed efficiently.

Further, in order to support the photocatalyst on the surface of the above-mentioned microspherical carbonaceous hollow body, the finely pulverized coal or pitch is rapidly heated in an inert atmosphere to thereby produce a fine spherical carbonaceous hollow body. A photocatalyst is supported on this, or a tetravalent titanium compound such as titanium isopropoxide or titanium tetrachloride (this is referred to as a "photocatalyst precursor" in the present invention) is added to finely pulverized coal or pitch. It was confirmed that impregnation as a solution or an aqueous solution was sufficient, and heating was performed rapidly under an inert atmosphere.

The use of a carbonaceous hollow body photocatalyst in which a photocatalyst is carried on the surface of the above-mentioned microspherical carbonaceous hollow body allows the use of organic compounds contained in wastewater, for example, BTX (benzene, Toluene, xylene), mixed oil such as lubricating oil, or pesticides can be easily decomposed.

The present invention has been made on the basis of the above findings, and the gist of the invention is as follows:
(2) and (3) the method for producing the catalyst and (4) the method for using the catalyst.

(1) A carbonaceous hollow body catalyst, wherein a photocatalyst is supported on the surface of a microspherical carbonaceous hollow body.

(2) The powdery carbonaceous material is rapidly heated in an inert atmosphere, and a photocatalyst is supported on the obtained microspherical carbonaceous hollow body. A method for producing a carbonaceous hollow catalyst.

(3) The carbonaceous hollow material according to the above (1), wherein after the photocatalyst precursor is supported on the powdery carbonaceous material, the material is rapidly heated in an inert atmosphere and then fired. A method for producing a body catalyst.

(4) A method for using a hollow carbonaceous catalyst, which comprises decomposing an organic compound contained in water using the hollow carbonaceous catalyst described in (1) above.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention (the above (1) to (1))
The invention (4) will be described in detail.

The carbonaceous hollow catalyst of the invention of the above (1) (hereinafter referred to as “the carbonaceous hollow catalyst of the present invention” in particular)
Is a catalyst in which a photocatalyst is supported on the surface of a fine spherical carbonaceous hollow body.

The microspherical carbonaceous hollow body described above has a bulk specific gravity of 0.02 to 0.1 g / h obtained by heating finely pulverized coal or pitch as a raw material.
It is a porous carbon particle having a particle size of 100 to 2500 μm in cm ³ . Even after carrying the photocatalyst, the apparent specific gravity is smaller than that of water, the material has a floating property (the property of floating on the water surface), and the specific surface area is extremely large.

A photocatalyst is a substance that exhibits a photocatalytic function when irradiated with light having a wavelength having energy equal to or greater than the band gap. Examples thereof include titanium oxide, zinc oxide, strontium titanate, tungsten oxide, yttrium oxide, and the like. Known metal oxide semiconductors such as iron oxide can be used. These semiconductor substances may be a single substance, or a mixture or a composite oxide in which two or more kinds are combined. As this photocatalyst, particularly, titanium oxide which has high photocatalytic activity, is chemically stable and harmless is preferable.

The amount of the photocatalyst carried by the microspherical carbonaceous hollow body of the present invention is not particularly limited as long as the hollow body can maintain the buoyancy while the photocatalyst is supported. However, in order to maintain the large specific surface area of the carbonaceous hollow body sufficiently and at the same time, the dispersibility of the photocatalyst is good and a higher photocatalytic activity can be obtained, the content is 100% by weight or less based on the carbonaceous hollow body. Is preferred. More preferably, it is 50% by weight or less.

The hollow carbonaceous material catalyst of the present invention has the following characteristics because it has a function of photooxidizing an organic compound and uses a microspherical carbonaceous hollow material as a carrier.

As in the case where a glassy hollow body is used as a carrier, it easily gathers on the water surface (has a floating property), so that sunlight easily reaches.

The microspherical carbonaceous hollow body has a large specific surface area like activated carbon.

The carbonaceous hollow catalyst can adsorb a substance to be oxidized similarly to activated carbon.

The invention (4) is a method of using the carbonaceous hollow body catalyst for decomposing an organic compound contained in water. That is, the present invention makes the most of the above-mentioned features of the carbonaceous hollow catalyst of the present invention, and uses the carbonaceous hollow catalyst to make use of the organic compounds contained in water, in particular, BTX, waste oil and the like contained in wastewater. Is a method of decomposing

No special equipment is required for using the carbonaceous hollow catalyst. For example, when this carbonaceous hollow body catalyst is added to and dispersed in wastewater containing the above-mentioned organic compound and stirred as necessary, the organic compound is adsorbed and concentrated on the catalyst surface. Further, when exposed to sunlight, the adsorbed organic compound is efficiently oxidatively decomposed by the photocatalyst particles of the carbonaceous hollow catalyst collected on the water surface.

Since the carbonaceous hollow catalyst has a characteristic that it easily gathers on the water surface, sunlight can be used without requiring a large light receiving area. In addition, the reaction efficiency is high because the specific surface area is large. Further, the organic compound can be adsorbed and removed even under the condition without light irradiation, and when the light is irradiated, the adsorbed organic compound can be oxidized and decomposed to recover the adsorbing ability. Therefore, it is possible to always maintain a constant high adsorption capacity, and it is suitable for repeated use. Therefore, it is particularly suitable for oxidative decomposition of organic compounds in wastewater, and efficient decomposition treatment is possible.

The hollow carbonaceous catalyst of the present invention is effective not only for removing organic compounds in wastewater but also for removing and decomposing organic compounds generally contained in water such as clean water, industrial water or seawater. Therefore, purification treatment of industrial wastewater and so-called domestic wastewater discharged from ordinary households, treatment of river water and groundwater containing harmful substances such as pesticides and organic halogen compounds, treatment of oil spilled at sea, red tide, etc. ,
Can be used in a wide range of fields.

The invention of the above (2) is a method for producing a carbonaceous hollow body catalyst according to the present invention, wherein the powdery carbonaceous material is rapidly heated in an inert atmosphere to obtain a microspherical hollow body. Is a method in which a photocatalyst is supported on the surface of the substrate.

The carbonaceous material used as a raw material is powdered coal, pitch, or the like, which is preferably finely pulverized so as to have a particle size of 5 mm or less.

These raw materials are rapidly heated under an inert atmosphere. The inert atmosphere is an atmosphere in which the raw material contains an insufficient amount of oxygen for complete combustion and the combustion proceeds in an incomplete state. If the amount of oxygen necessary for complete combustion or an excess amount of oxygen is present, the coal and the pitch are completely burned, and the desired microscopic carbonaceous hollow body cannot be obtained.

The heating is carried out to gasify and separate volatile components contained in the raw material and to carbonize the remainder, and the heating temperature is preferably set to 600 to 900 ° C. When the heating temperature is lower than 600 ° C., the volatile components contained in the raw material are not sufficiently gasified, and the specific gravity of the obtained carbonaceous hollow body tends to increase. On the other hand, if the temperature exceeds 900 ° C., the cost required for heating increases, which is not economical.

In order to obtain a carbonaceous hollow body having a large specific surface area, it is necessary to rapidly expand bubbles including gas generated by gasification, including those generated inside the particles, and the material is rapidly heated. With gentle heating, the carbonization is completed before the growth of the bubbles themselves is slow and they do not expand sufficiently, so that a carbonaceous hollow body having a large specific surface area having many pores cannot be obtained. The rapid heating is preferably performed at a heating rate of 200 to 600 ° C./sec over the entire temperature range from around room temperature to the above-mentioned heating temperature (600 to 900 ° C.).

In order to perform the above-mentioned rapid heating, it is preferable to use a fluidized bed type or gas bed type reactor.
Using these reactors, starting from the downstream of a reactor having a reaction zone heated to, for example, 600 to 900 ° C.,
By supplying a gas containing an insufficient amount of oxygen to completely burn the raw material, the raw material is incompletely burned in the above-mentioned inert atmosphere.

As described above, under the condition that the combustion proceeds in an incomplete state, a part of the raw material such as coal and pitch can be used as a heat source. In this case, the yield of the target carbonaceous hollow body is reduced, but it is preferable because the steam generated by combustion of a part of the raw material activates the generated microspherical carbonaceous hollow body.

Since the fine spherical carbonaceous hollow bodies generated by such a heat treatment are discharged together with the gas containing the combustion gas from the upstream part of the reactor, they are separated from the gas by filtration, specific gravity separation or the like.

The resulting microspherical carbonaceous hollow body has a bulk specific gravity of 0.02 to 0.1 g / cm ³ and a particle diameter of 100
２2500 μm. The properties greatly depend on the properties of the raw materials used (especially, the amount of volatile components and the amount of ash), but in order to obtain a fine spherical carbonaceous hollow body of appropriate properties,
The length of the reaction zone in the reactor, the feed rate of the raw material and the inert gas, and the like are appropriately adjusted.

The above-mentioned photocatalyst is carried on the fine spherical carbonaceous hollow body thus obtained.

The method for supporting the photocatalyst is not particularly limited, and the photocatalyst can be supported by a usual catalyst preparation method such as an impregnation method or a kneading method.

For example, when supporting titanium oxide, a tetravalent titanium compound such as titanium isoproxide, titanium tetrachloride, titanium sulfate, etc. (that is, a photocatalyst precursor)
After the carbonaceous hollow body is sufficiently immersed in the alcohol solution or aqueous solution of the above to impregnate the titanium compound, the carbonaceous hollow body is separated by filtration, centrifugation or the like. Then air-dry,
Alternatively, the titanium compound is hydrolyzed by performing steam treatment as needed, and then dried and calcined to obtain the desired carbonaceous hollow catalyst.

The calcination is carried out in order to firmly support the photocatalyst in the carbonaceous hollow body and to provide durability, and it is desirable to carry out the calcination in a non-oxidizing atmosphere such as nitrogen or argon.
When firing at a temperature lower than the temperature at which the carbonaceous material does not burn, the firing may be performed in air. The sintering temperature is not particularly limited, and may be any temperature as long as a so-called sintering phenomenon occurs in which bonding occurs between the particles of the supported photocatalyst and solidifies.
However, in the case of titanium dioxide, it is necessary to select calcination conditions that include many anatase crystals having high photocatalytic activity.

According to the method described above, the carbonaceous hollow catalyst of the present invention can be easily produced without requiring any special means.

The invention of the above (3) is also a method for producing a hollow carbonaceous catalyst according to the present invention, wherein a photocatalyst precursor is supported on a carbonaceous material, then rapidly heated, and further heated under an inert atmosphere. This is a firing method.

As the carbonaceous material, powdered coal, pitch or the like is used as in the invention of the above (2). Finely pulverized so that the particle size becomes 5 mm or less is preferable.

The photocatalyst precursor is, as described above, a tetravalent titanium compound such as titanium isoproxide, titanium tetrachloride, and titanium sulfate. The titanium compound is obtained by sufficiently immersing the carbonaceous material in an alcohol solution or an aqueous solution thereof. After impregnation, the carbonaceous material is separated by filtration, centrifugation or the like.

Next, the carbonaceous material impregnated with the photocatalyst precursor is rapidly heated in an inert atmosphere. The inert atmosphere is an atmosphere in which an insufficient amount of oxygen is contained for complete combustion of the raw material and combustion proceeds in an incomplete state, as in the case of the invention (2). If the amount of oxygen required for complete combustion or an excess amount of oxygen is present, the carbonaceous material will be completely burnt, and the desired carbonaceous hollow body catalyst cannot be obtained.

The heating temperature is preferably from 600 to 900 ° C. If the heating temperature is lower than 600 ° C., the gasification of volatile components contained in the raw material is not sufficient, and the specific gravity of the obtained hollow body tends to increase. On the other hand, if the temperature exceeds 900 ° C., the cost required for heating increases.

The heating is rapid. As a result, a carbonaceous hollow body having a large specific surface area can be obtained in the same manner as described in the invention of the above (2), and further, the carboxyl group or the hydroxyl group of the carbonaceous material (coal, pitch, etc.) and A new bond is created with the substance. That is, the photocatalyst is in a state of being chemically fixed to the carbonaceous hollow body, and its stability is improved. Incidentally, the rapid heating is carried out from the vicinity of room temperature to the above-mentioned heating temperature (600 to 9) as in the case of the invention (2).
200-600 over the entire temperature range up to
The heating is preferably performed at a heating rate of ° C / sec.

In order to perform the above-mentioned rapid heating, for example, a high-temperature tank such as an electric furnace or a muffle furnace is used, and is heated in advance to a temperature at which the above-mentioned bonding occurs between the carbonaceous material and the photocatalyst precursor. Preferably, a carbonaceous material impregnated with the photocatalyst precursor is charged therein and heated.

After the rapid heating is completed, firing is further performed. The sintering is carried out to sinter the particles of the photocatalyst fixed in the carbonaceous hollow body more firmly as in the case of the invention (2), and is an object of the present invention. As long as the carbonaceous material of the carbonaceous hollow catalyst does not burn, the atmosphere during firing is not particularly limited. nitrogen,
It is desirable to carry out in a non-oxidizing atmosphere such as argon, but when firing at a temperature below the temperature at which carbonaceous material does not burn, it may be carried out in air.

The sintering temperature is not particularly limited as long as the sintering phenomenon occurs. However, in the case of titanium dioxide, it is necessary to select calcination conditions such that many anatase crystals having high photocatalytic activity are contained, as in the invention of (2).

If the above-mentioned high temperature tank capable of rapidly increasing the temperature of the charge is used, for example, the raw material is charged into a high temperature tank heated to 600 to 900 ° C. and held as it is, thereby rapidly heating the material. At the same time, baking can be performed, which is preferable.

According to the method (3), the carbonaceous hollow catalyst of the present invention can be easily produced without requiring any special means.

When the invention of the above (2) is compared with the invention of the above (3), the invention of the above (2) provides a relatively light one, whereas the invention of the above (3) has a large specific surface area. Things tend to be obtained. In addition, in the invention of (3), the yield of the obtained carbonaceous hollow catalyst is low, but the yield is low via the functional groups (carboxyl group, hydroxyl group, etc.) of the constituent molecules such as coal used as the carbonaceous material. Thus, a photocatalyst such as titanium dioxide can be strongly bonded to the carbonaceous hollow body.

Therefore, the type, concentration, and the like of the organic compound contained in the object to be treated using the carbonaceous hollow catalyst are described.
Alternatively, it is possible to use a catalyst suitable for each condition by properly using a production method according to a processing environment.

[0058]

【Example】

(Example 1) As a carbonaceous material (a raw material of a carbonaceous hollow body), a sub-bituminous coal (having a volatile component of 46
%, Anhydrous ash-free basis), and this was charged into a gas-bed reactor and subjected to a heat treatment of rapidly raising the temperature to 600 ° C. (reaction time: 3 seconds), and the resulting carbonaceous hollow body was treated with water. By flotation, a floating microspherical carbonaceous hollow body was obtained. Its bulk specific gravity is 0.
09 g / cm ³ , and the BET specific surface area was 100 cm ² / g.

10 g of this carbonaceous hollow body, 30 g of titanium isoproxide and 30 ml of ethanol (ml)
Into the mixed solution, while applying ultrasonic waves as appropriate.
Stirred gently for hours. Next, the suspended matter was separated by filtration, air-dried for 24 hours, dried in air at 250 ° C. for 2 hours, and subsequently calcined at 600 ° C. for 5 hours in a nitrogen stream (200 ml / min) to obtain titanium oxide. Was supported on the carbonaceous hollow body in an amount of 30% by weight to obtain a carbonaceous hollow body catalyst. It was confirmed by X-ray diffraction that the supported titanium oxide was an anatase crystal.

Using the carbonaceous hollow catalyst thus obtained, benzene added to distilled water was oxidized.

First, a flat cell (manufactured by Pyrex, having an inner diameter of 6)
30 cm ³ of a mixture obtained by adding benzene to distilled water so as to have a concentration of 50 mmol / l (mmol / l).
g was added and dispersed, and covered with a quartz disk. Then
Under air-saturated condition, magnetic stirring was performed gently without light irradiation (500 rpm), and after 1 hour, the benzene concentration in the liquid was measured. This is a test performed on the assumption that sunlight cannot be used.

Thereafter, at 25 ° C., 250
Light from a high-pressure mercury lamp of W was irradiated through a UV cut filter (UV-31 manufactured by Toshiba) to cause a reaction. In addition,
At the time of the reaction, it was confirmed that the catalyst was present in a floating state on the liquid surface, and that light was applied to the entire surface.

Analysis of benzene and its decomposition products
The liquid phase was analyzed by high performance liquid chromatography (column: TSK-gel ODS-80TS manufactured by Tosoh), and the gas phase was analyzed by gas chromatography (column: UNIBEADS-C manufactured by GL Sciences).

As a result, benzene was adsorbed on the carbonaceous hollow body catalyst while being stirred gently without irradiation with light, and the concentration was 50 mmol / l to 10.5 mmol / l in 1 hour.
l. Also, after that, by light irradiation for 4 hours,
Benzene is oxidatively decomposed and carbon dioxide is 0.88 mmol
1, 0.07 mmol of carbon monoxide was produced.

Example 2 80 g of titanium isoproxide
Is dropped into 500 cm ³ of vigorously stirred distilled water,
Thereafter, 5 g of nitric acid (60%) was added. Then, the mixture was stirred at 80 ° C. for 24 hours and concentrated under vacuum.
The pH was adjusted by adding an N sodium hydroxide solution to obtain a sol solution (pH about 3.0) containing 10% by weight of titanium oxide.

10 g of the carbonaceous hollow body not supporting titanium oxide prepared in Example 1 was added to this sol solution, and the mixture was gently stirred for 5 hours. Thereafter, the suspended matter was separated by filtration, sufficiently washed with distilled water, and then calcined in air at 250 ° C. for 2 hours to obtain a carbonaceous hollow catalyst carrying 45% by weight of titanium oxide. It was confirmed by X-ray diffraction that this titanium oxide was present as an anatase type crystal.

Using the carbonaceous hollow catalyst thus obtained, benzene was oxidized. The oxidation conditions and analysis method were the same as in Example 1.

As a result, the concentration of benzene was reduced from 50 mmol / l to 12.4 mmol / l due to adsorption to the carbonaceous hollow body catalyst during gentle stirring without light irradiation. In addition, benzene was oxidatively decomposed by light irradiation for 4 hours thereafter, and 1.15 mmol of carbon dioxide and 0.025 mmol of carbon monoxide were produced.

Example 3 Example 1 was used as a carbonaceous material.
The sub-bituminous coal (having a volatile component of 46%, based on anhydrous ashless) pulverized to a particle size of 0.5 to 3 mm used for
30 g of titanium isoproxide was placed in a solution mixed with 30 ml of ethanol, and gently stirred for 3 hours while appropriately applying ultrasonic waves. Then, the suspended matter was separated by filtration,
After air-drying for 4 hours, it is dried in air at 250 ° C. for 2 hours, and then placed in a high-temperature bath maintained at 600 ° C. in a nitrogen atmosphere and calcined for 5 hours. 6 g of a porous hollow catalyst was obtained. The ratio of titanium oxide to the carbonaceous hollow catalyst was 35% by weight, and it was confirmed by X-ray diffraction that the titanium oxide was an anatase crystal.

The carbonaceous hollow body catalyst obtained in this way includes a catalyst floating on water and a catalyst sinking in water. The same method as in Example 1 is used with both of them mixed. Oxidized benzene in the aqueous solution. The oxidation conditions and analysis method were the same as in Example 1.

As a result, the benzene was adsorbed on the carbonaceous hollow catalyst during the gentle stirring without light irradiation, and the concentration of benzene was reduced from 50 mmol / l to 10 mmol / l in 1 hour.
Decreased to. In addition, benzene was oxidatively decomposed by light irradiation for 4 hours, and 0.9 mmol of carbon dioxide and 0.08 mmol of carbon monoxide were produced.

(Example 4) 0.1 g of petroleum-based industrial lubricating oil used in an ironworks was added to 30 ml of water, and 0.5 g of the carbonaceous hollow catalyst prepared in Example 1 was dispersed therein. Using the liquid, an oxidative decomposition test of the lubricating oil was conducted in the same manner as in Example 1. The amount of lubricating oil in water was measured by filtering the catalyst, extracting lubricating oil from the filtrate using chloroform, and measuring the absorbance of the extract.

As a result, about 80% of the lubricating oil was adsorbed on the carbonaceous hollow body during gentle stirring without light irradiation.
After that, the lubricating oil is oxidatively decomposed by light irradiation for 4 hours, and 1.3 mmol of carbon dioxide and 0.1 mmol of carbon monoxide.
30 mmol was produced.

(Comparative Example 1) Instead of the carbonaceous hollow catalyst, commercially available titanium oxide (P-25, manufactured by Nippon Aerosil) 0.3
g was used as a catalyst, and benzene was oxidized under the same conditions as in Example 1 except for the above.

As a result, the benzene concentration hardly decreased during gentle stirring without light irradiation, and no benzene adsorption was observed. Further, the light irradiation for 4 hours thereafter produced 0.19 mmol of carbon dioxide and 0.062 mmol of carbon monoxide, but the amounts were much smaller than those in Examples 1 and 2.

(Comparative Example 2) Instead of the carbonaceous hollow body catalyst, a separately prepared glass hollow body supporting titanium oxide composed of anatase type crystal (amount of titanium oxide: 20.4 weight per glass hollow body) %) As a catalyst, and benzene was oxidized under the same conditions as in Example 1 except for the above. At this time, it was confirmed that the catalyst floated on the liquid surface in the same manner as in the case of using the carbonaceous hollow body catalyst, and light was applied to the entire surface.

As a result, the concentration of benzene was changed from 50 mmol / l to 47.3 mmol /
The benzene adsorption was only slightly noticeable. Further, after irradiation for 4 hours, 0.27 mmol of carbon dioxide and a trace amount of carbon monoxide were generated, but the amounts were smaller than those in Examples 1 and 2.

(Comparative Example 3) A commercially available activated carbon (manufactured by Wako Pure Chemical Industries, Ltd.) was used in place of the carbonaceous hollow body. Activated carbon (catalyst) supported by weight% was obtained. This catalyst was used in place of the carbonaceous hollow body catalyst, and benzene was oxidized under the same conditions as in Example 1 except for that. At this time, the catalyst tended to settle on the bottom surface of the vessel used for the treatment and to slightly aggregate.

As a result, during stirring without irradiation with light, the benzene concentration was reduced from 50 mmol / l to 7.3 mmol / l, and adsorption of benzene was observed. In addition, although 0.65 mmol of carbon dioxide and 0.084 mmol of carbon monoxide were produced by light irradiation, the amounts thereof were smaller than those of Examples 1 and 2 in spite of the higher benzene adsorption. This is mainly because the effect of light irradiation was reduced because the catalyst settled or aggregated in the vessel.

Comparative Example 4 Commercially available titanium oxide (Nippon Aerosil P-25) 0.3 was used instead of the carbonaceous hollow catalyst.
g was used as a catalyst, and an oxidative decomposition test of petroleum-based industrial lubricating oil was performed under the same conditions as in Example 4 except for the above.

As a result, the lubricating oil was scarcely adsorbed on the carbonaceous hollow body even if it was gently stirred without irradiation with light.
Further, the lubricating oil was oxidatively decomposed by light irradiation for 4 hours thereafter to produce 0.31 mmol of carbon dioxide and 0.12 mmol of carbon monoxide, but the amounts were much smaller than those in Example 4. Was.

[0082]

The carbonaceous hollow body catalyst of the present invention has a function of photooxidizing an organic compound, and since it uses a carbonaceous hollow body having a large specific surface area as a carrier, it has excellent adsorption capacity for a substance to be oxidized. In addition to having high reaction efficiency, it has the characteristic of being easily collected on the water surface where sunlight can easily reach. Therefore, sunlight can be used without requiring a large light receiving area, and is particularly suitable for oxidative decomposition of organic compounds in wastewater.

This carbonaceous hollow catalyst can be easily produced by the method of the present invention.

Claims (4)

[Claims] 1. A carbonaceous hollow body catalyst, wherein a photocatalyst is supported on the surface of a microspherical carbonaceous hollow body. 2. The carbonaceous material according to claim 1, wherein the powdery carbonaceous material is rapidly heated in an inert atmosphere, and a photocatalyst is carried on the obtained microspherical carbonaceous hollow body. A method for producing a hollow body catalyst. 3. The carbonaceous hollow body catalyst according to claim 1, wherein the photocatalyst precursor is supported on the powdery carbonaceous material, and then heated rapidly in an inert atmosphere and then calcined. Manufacturing method. 4. A method for using a carbonaceous hollow body catalyst, comprising decomposing an organic compound contained in water using the carbonaceous hollow body catalyst according to claim 1.