JP2003200050A - Decomposition catalyst for ammonia and organic compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a simultaneous oxidative decomposition catalyst for ammonia and an organic compound, both contained in various kinds of waste gases, which subjects ammonia to oxidative decomposition into gaseous nitrogen and water and simultaneously subjects the organic compound to oxidative decomposition into gaseous carbon dioxide and water, and to provide a method for removing them by using the catalyst. <P>SOLUTION: The simultaneous oxidative decomposition catalyst for ammonia and the organic compound is characterized by containing a catalyst A component which is an oxide containing Ti, a catalyst B component which is an oxide of at least one kind of metal selected from the group consisting of vanadium, tungsten and molybdenum and a catalyst C component which is at least one kind of noble metal or a compound thereof selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is designed to remove harmful ammonia (NH3) contained in various exhaust gases from nitrogen gas (N2) and water (H).
Ammonia and organic compound simultaneous oxidative decomposition catalyst for oxidizing and decomposing organic compounds into carbon dioxide gas (CO2) and water (H2O), and decomposition method of ammonia and organic compounds using the catalyst Regarding As the gas containing ammonia and organic compounds, there are gases discharged from human waste / livestock excrement, activated sludge, food waste, agricultural wastes, sewage treatment activated sludge, facilities for treating organic waste such as garbage, and the like.

[0002]

2. Description of the Related Art Methods for treating organic waste such as human waste / livestock excrement, activated sludge, food waste, agricultural waste, sewage treatment activated sludge and raw garbage include methane fermentation treatment and carbonization treatment. In particular, the carbonization device is compact and has a low cost, and has been attracting attention in recent years. As a carbonization process, there are generally two steps of a pretreatment step of drying organic waste such as human waste and livestock excreta to a certain extent, and then a carbonization step for carbonization.
However, both of these processes have a drawback that ammonia and organic compounds in organic waste such as human waste and livestock excrement are discharged as gas. In recent years, methods for treating ammonia and organic compounds discharged from these steps have been investigated.

Direct combustion methods and catalytic oxidation methods are mentioned as methods for treating ammonia and organic compounds. The direct combustion method requires a high temperature (800 ° C or higher), which causes a problem of high running cost. Further, organic compounds can be made harmless, but since they contain ammonia, there is a problem that nitrogen oxide (NO _x ) is generated by direct combustion at high temperature. Since the catalytic oxidation method does not require high temperature, the running cost can be lower than that of direct combustion,
In addition, although organic compounds can be treated, there is a problem that nitrogen oxides (NO _x ) are generated when a conventional noble metal catalyst (eg Pt / Al2O3) is used as in the direct combustion method. In this way, when treating organic wastes, especially ammonia and organic compounds generated during carbonization are efficiently generated, and a large amount of nitrogen oxides are not generated, that is, ammonia and organic compounds having a high selectivity to nitrogen and water. There is a strong demand for the decomposition characteristics of compounds. Furthermore, human waste, livestock manure, activated sludge, food waste,
Agricultural crop waste, sewage treatment, activated sludge and organic waste such as garbage are treated with gases such as sulfur oxides, hydrogen sulfide, sulfur-containing organic compounds, nitrogen-containing organic compounds, etc. along with ammonia and organic compounds. In many cases, the components that cause the malodorous substances are contained, and it is necessary to treat these components as well. The conventional catalyst (eg, Pt / Al2O3) has a problem that the durability is remarkably reduced when the processing gas contains a sulfur-containing organic compound. Further, when the process gas contains other nitrogen-containing organic compounds in addition to ammonia and organic compounds, there are problems that the ammonia decomposing activity decreases and NOx production increases.

[0004]

The object of the present invention is to exhibit high ammonia and organic compound decomposing activity in a wide temperature range from low temperature to high temperature even in the presence of excess oxygen and other nitrogen-containing organic compounds, and NOx. Ammonia and organic compounds are simultaneously oxidized and decomposed at a very low level, and have excellent durability even when a sulfur compound is contained in the process gas. Sulfur oxidation is carried out with ammonia and organic compounds by using the ammonia and organic compound decomposition catalysts. The object of the present invention is to provide a method for simultaneously oxidizing and decomposing a gas containing at least one compound selected from organic compounds, hydrogen sulfide, sulfur-containing organic compounds and nitrogen-containing organic compounds.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors selected an oxide containing Ti, and further selected the oxide containing Ti as an oxide of a specific metal. It has been found that the target high activity and long life ammonia and organic compound simultaneous oxidative decomposition catalyst can be obtained by combining with a noble metal component. Further, when the catalyst is applied to a gas containing ammonia and an organic compound and at least one compound selected from the group consisting of sulfur oxides, hydrogen sulfide, sulfur-containing organic compounds and nitrogen-containing organic compounds, excellent simultaneous oxidative decomposition It was also found that the treatment effect was exhibited, and the present invention was completed. That is, the present invention is specified as follows. (1) a catalyst A component which is an oxide containing Ti, and a catalyst B component which is an oxide of at least one metal selected from the group consisting of vanadium, tungsten and molybdenum,
A catalyst for simultaneous oxidative decomposition of ammonia and an organic compound, which comprises at least one noble metal selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium, or a catalyst C component which is a compound thereof. (2) Binary compound oxide containing Ti and Si as catalyst A component; Binary compound oxide containing Ti and Zr; At least one of ternary compound oxide containing Ti, Si and Zr The catalyst for simultaneous oxidative decomposition of ammonia and an organic compound according to (1) above, which uses one kind of composite oxide. (3) A method for simultaneous oxidative decomposition of ammonia and an organic compound using the catalyst according to (1) or (2) above. (4) In a gas containing ammonia and an organic compound and at least one compound selected from the group consisting of sulfur oxides, hydrogen sulfide, sulfur-containing organic compounds and nitrogen-containing organic compounds, the above (1) or (2) is described. Method for simultaneous oxidative decomposition of ammonia and organic compounds using the catalyst of. (5) The method for simultaneous oxidative decomposition of ammonia and an organic compound according to (3) or (4) above, wherein the gas temperature of the gas containing ammonia and the organic compound is controlled to 280 ° C. to 400 ° C. and introduced into the catalyst layer. (6) Ammonia and organic compound-containing gas is a gas generated when carbonizing organic waste such as human waste / livestock excrement, activated sludge, food waste, agricultural waste and raw garbage, and sewage activated sludge. (3) A method for simultaneous oxidative decomposition of ammonia and an organic compound according to any one of (5). The present invention will be described in more detail below.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The organic compound to be treated in the present invention is one containing C and H, or C, H and O in the molecule, and includes, for example, methane, ethane, propane, butane, Saturated hydrocarbons such as pentane and hexane; unsaturated hydrocarbons such as ethylene, acetylene, propylene, propyne, butene, butyne, pentene, pentin, hexene and hexine; cyclohexane, cyclohexene, cyclopentane, cyclopentene, cycloheptane and cycloheptene Alicyclic hydrocarbons; alcohols such as methanol, ethanol, propanol, butanol; aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde; acetone, methyl ethyl ketone, methyl propyl ketone, a Ketones such as tophenone and methyl isobutyl ketone; ethers such as methyl ether, ethyl ether, propyl ether, butyl ether, methyl ethyl ether, vinyl ether, dioxane; esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, vinyl acetate Aromatic compounds such as benzene, ethylbenzene, toluene, xylene, styrene, phenol, cumene; organic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, tartaric acid, phthalic acid, maleic acid and benzoic acid You can
Among the above compounds, it is particularly preferably used for decomposing aldehydes, organic acids, benzene, toluene, xylene and the like.

Of the components constituting the ammonia and organic compound decomposition catalysts of the present invention, the first feature is that a specific metal, that is, an oxide containing at least Ti is used as the catalyst component A. Examples of the oxide containing Ti include antase type titanium, rutile type titanium, a composite oxide containing Ti and another metal, and the like, more preferably a composite oxide containing Ti and another metal, such as Ti and A binary composite oxide composed of Si, a binary composite oxide composed of Ti and Zr and a ternary composite oxide composed of Ti, Si and Zr are recommended.

Binary composite oxides generally composed of titanium and silicon, for example, Kozo Tabe (Catalyst, Vol. 17, No.
3, 72, 1975), it is known as a solid acid, and each of them has a remarkable acidity which is not found in a single oxide, and has a high surface area. That is, the above-mentioned TiO2-SiO2 (composite oxide of titanium and silicon; hereinafter, "-" is sometimes used between oxides as an indication of each complex oxide) is titanium oxide. It is recognized that titanium and silicon are not a mixture of silicon oxide and silicon oxide, but titanium and silicon form a so-called binary oxide to exhibit their specific physical properties. Also, a ternary compound oxide composed of titanium, silicon and zirconium is used as TiO2.
-A composite oxide having the same properties as SiO2. Further, the above complex oxide was analyzed by X-ray diffraction,
It was found to have a fine structure that is amorphous or nearly amorphous.

The reason why such a metal composite oxide in the present invention brings excellent effects is not clear, but
It is considered that this is attributed to the properties of the composite oxide, which are not observed by the oxides constituting the metal composite oxide alone, that is, ammonia adsorption performance, high surface area, high pore volume, sulfur compound resistance, and the like. That is, the composite oxide used in the present invention is not easily affected by sulfur oxides coexisting in the gas, has excellent ammonia adsorption performance, has a high surface area and a high pore volume, and has a high active component of the catalyst. Since it can be dispersed, it is presumed that a small amount of active ingredient exhibits high activity in a wide temperature range and a long-life catalyst can be obtained without thermal deterioration due to sintering. Regarding the above points, the effect can be more clearly understood by comparing a commonly used oxide such as alumina with the composite oxide according to the present invention. For example, when alumina is used instead of the composite oxide according to the present invention, the organic compound is efficiently decomposed, but the activity of ammonia (decomposition into water and nitrogen gas) becomes low, and the sulfur compound is added to the gas to be treated. In the presence of a, alumina sulphates, resulting in a decrease in decomposition activity of ammonia and organic compounds and a decrease in catalyst strength.

When silica is used, the decomposition activity of the organic compound is efficiently decomposed, but the decomposition activity of ammonia is low, and sintering is caused at a high temperature, especially when a gas containing water is treated, and the surface area is greatly reduced. To occur,
Furthermore, the decomposition activity of ammonia and organic compounds is lowered.

When zeolite is used, it is inferior in heat resistance, its crystal structure changes under high temperature conditions to cause a large decrease in surface area, and the activity of decomposing ammonia and organic compounds also remarkably decreases. The above-mentioned drawbacks are few in the composite oxide according to the present invention and are effective as a catalyst for decomposing ammonia and organic compounds.

When the catalyst A component and the catalyst B component, which are oxides containing Ti according to the present invention, are combined, NOx is hardly generated by decomposition of ammonia, and the process gas contains NOx. However, NOx is hardly present in the outlet gas due to the denitration reaction by ammonia. However, organic compounds cannot be treated at low temperatures, and when NOx does not exist in the treated gas, the ammonia decomposing activity becomes low especially at low temperatures.
Further, when the catalysts A and C are combined, it is excellent in the activity of decomposing ammonia and organic compounds, but NO
The generation of x becomes high, which is not preferable.

On the other hand, by combining the catalysts A, B and C components, in addition to the fact that the catalyst A component is also excellent in ammonia adsorption capacity, the functions of the catalysts B and C can be effectively exhibited. It is possible to obtain the synergistic effect that the organic compound decomposing activity and the generation of NOx can be reduced.

For these reasons, the physical properties and composition of the catalyst A component used in the present invention have a great influence on the characteristics of the ammonia and organic compound decomposition catalysts of the present invention. For example, the BET surface area is preferably 30 m2 / g or more, more preferably 40 m2 / g or more, because if it is too low, the activity of decomposing ammonia and organic compounds is low and the durability is also reduced. The upper limit of the surface area is not particularly limited, but the metal composite oxide in the present invention generally has a surface area of 1000 m 2 / g or less, and more preferably 40 to 300 m 2 / g. If it is less than 40 m 2 / g, the activity of decomposing ammonia and organic compounds will be low, and if it exceeds 1000 m 2 / g, the initial activity will be high, but the change over time in catalyst performance may become large, so it is suitable for long-term use. May be unfavorable.

The two-component composite oxide of the present invention, Ti
O 2 --SiO 2 or TiO 2 --ZrO 2 binary complex oxide, and of these, considering the size of the surface area, the ease of decomposition of ammonia and organic compounds, etc., preferably,
It is a composite oxide of TiO2-SiO2.

Further, TiO2-SiO2 or TiO2-Zr
The composition ratio of each component in the case of a binary compound oxide of O2 is converted to an oxide (TiO2 for titanium oxide, SiO2 for silicon oxide, ZrO2 for zirconium oxide), and the total molar amount of the two components is 100 mol. %, TiO2-Si
When it is a binary compound oxide of O2, the TiO2 content is 40-
It is 95 mol%, preferably 60 to 95 mol%. 40
This is because when it is less than mol% and when it exceeds 95 mol%, the decomposability of ammonia and the organic compound becomes low.

When it is a binary compound oxide of TiO2-ZrO2, TiO2 is 45 to 98 mol%, preferably 6%.
It is 5 to 95 mol%. When it is less than 45 mol%,
This is because the decomposition activity of ammonia and the organic compound also becomes low because the surface area becomes low, and when it exceeds 98 mol%, the decomposition activity of the ammonia and the organic compound becomes low.

When the catalyst A component is a ternary complex oxide, the composition ratio is converted to oxide (titanium oxide is TiO 2).
2, silicon oxide is SiO2, zirconium oxide is ZrO
When the total of 2) is 100 mol%, TiO2 is 40 to 40%.
It is preferably in the range of 95 mol%, more preferably 60 to 95 mol%. When TiO2 exceeds the range, the characteristics of the composite oxide are not sufficiently exhibited, and when it is below the range, the catalytic activity decreases.

SiO 2 is 1 to 60 mol%, preferably
This is because when the amount is less than 5 to 40 mol% and less than 1 mol%, the surface area becomes low and the activity of decomposing ammonia and organic compounds also becomes low, and when it exceeds 60 mol%, the activity of decomposing ammonia and organic compounds becomes low. Is.

ZrO 2 is 1 to 55 mol%, preferably,
If it is 5 to 40 mol%, less than 1 mol%, the above properties as a ternary complex oxide are not sufficiently exhibited, and if it exceeds 55 mol%, the surface area is low and the decomposition activity of ammonia and organic compounds is also low. It will be lower.

In the present invention, the binary composite oxide and the ternary composite oxide may be used together depending on the use conditions.

The method for preparing such a metal complex oxide will be described with reference to a binary complex oxide composed of, for example, Ti and Si. As the titanium source, an inorganic titanium compound such as titanium chloride or titanium sulfate, or tetraisoprovir. It can be appropriately selected and used from organic titanium compounds such as titanate. Further, as the silicon source, colloidal silica,
Water glass, fine particle silicic acid, inorganic silicon compounds such as silicon tetrachloride, organic silicon compounds such as tetraethyl silicate, and the like can be appropriately selected and used. Some of these raw materials may contain trace amounts of impurities, contaminants, etc., but if they are in a certain amount, they do not significantly affect the physical properties of the target titanium-silicon composite oxide. So it can be used without problems. A preferred method for preparing the above titanium-silicon composite oxide can be achieved by the following procedure. (1) Titanium tetrachloride is mixed with silica sol, ammonia is added to cause precipitation, the obtained precipitate is washed, dried, and then calcined at 300 to 650 ° C. to obtain a target composite. You can (2) An aqueous sodium silicate solution is added to titanium tetrachloride to cause a reaction to cause a precipitate, the resulting precipitate is washed and dried, and then calcined at 300 to 650 ° C. to obtain a target composite. You can (3) To a water-alcohol solution of titanium tetrachloride, ethyl silicate ((C3H6O) 4Si) was added, followed by hydrolysis to produce a precipitate, which was washed, dried, and then Firing at 300-650 ° C,
The desired composite can be obtained. (4) Ammonia is added to a water-alcohol solution of titanium oxide chloride (TiOCl3) and ethyl silicate to cause precipitation, and the resulting precipitate is washed, dried, and then calcined at 300 to 650 ° C. , The target compound can be obtained. Among the above methods, the method (1) is particularly preferable, and more specifically, the titanium source (TiO2) and the silicon source (SiO2) are taken in a predetermined molar ratio to prepare an acidic aqueous solution or sol state ( 1 to 100 g / liter (hereinafter referred to as L, this amount is in the form of an acidic aqueous solution or sol having a titanium source of TiO2 and a silicon source of SiO2)
C., ammonia water as a neutralizing agent was added dropwise thereto, and the mixture was maintained at pH 2 to 10 for 10 minutes to 3 hours to form a coprecipitate with titanium and silicon. The precipitate was filtered,
After thorough washing, it is dried at 80 ° C to 140 ° C for 10 minutes to 3 hours, and calcined at 400 to 700 ° C for 1 to 10 hours.
A silicon composite oxide can be obtained. Further, instead of silicon, zirconium chloride, zirconium nitrate, inorganic zirconium compounds such as zirconium sulfate, or organic zirconium such as zirconium oxalate, or in some cases by using a zirconia sol, titanium-zirconia composite oxide titania- A composite oxide of zirconia and titanium-silica-zirconia can be obtained.

The addition of the catalyst B component, ie, the oxide of at least one metal selected from the group consisting of vanadium, tungsten and molybdenum, which is the second feature of the present invention, to the powder or slurry of the above complex oxide. It is also possible to add and mix such metal salts or a solution thereof and knead with a kneader or the like to form a honeycomb shape, or to form a composite obtained by molding, drying and firing the composite oxide. It is also possible to add it by a method of impregnating and supporting a solution of such a metal salt. Examples of such metal salts include ammonium metavanadate, ammonium paratungstate, and ammonium paramolybdate.

The catalyst C component which is the third feature of the present invention, that is, at least one noble metal selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium, or a compound thereof is the catalyst A component or the catalyst A component. To the powder or slurry of the mixture of the catalyst B component and, for example, salts of these noble metals or solutions thereof,
Alternatively, the catalyst A component or a molded product composed of the catalyst A component and the catalyst B component can be added by a method of impregnating and supporting a solution of these noble metal salts.

That is, the molded body of the simultaneous oxidative decomposition catalyst of ammonia and organic compound provided by the present invention is molded from powder or slurry of the above-mentioned catalyst A component, catalyst B component, catalyst C component or salts thereof. It may be used, or the catalyst C component may be supported on the molded body composed of the catalyst A component and the catalyst B component, and the catalyst B component and the catalyst C component may be supported on the molded body composed of the catalyst A component. It can also be used. Further, the catalyst composition obtained by the present invention has a plate shape, a corrugated plate shape, a net shape, a honeycomb shape, a columnar shape,
It may be molded into a cylindrical shape or the like, or may be formed of alumina, silica, silica-alumina, cordierite, titania, a plate made of stainless metal, a corrugated plate, a net,
It may be used by supporting it on a carrier having a honeycomb shape, a column shape, a cylindrical shape, or the like.

In the catalyst for decomposing ammonia and organic compounds thus obtained according to the present invention, the composition ratio of the catalyst A component to the catalyst B component and the catalyst C component has a great influence on the ammonia and organic compound decomposing characteristics. If the amount of the catalyst A component is too large, the effect of adding the components of the catalyst B and the catalyst C cannot be sufficiently obtained, and if it is too small, the activity of decomposing ammonia and organic compounds is lowered. If the amount of the component B of the catalyst is too small, the catalytic activity at high temperature becomes low, and even if it exceeds a certain level, the catalytic activity is not significantly improved. Also,
When the amount of the catalyst C component is small, the activity of decomposing the ammonia and the organic compounds, particularly the activity of decomposing the ammonia and the organic compounds at a low temperature becomes low. You will be able to see.

The component B of the catalyst according to the present invention is an oxide of at least one metal selected from the group consisting of vanadium, tungsten and molybdenum. Of these components, at least one of vanadium and tungsten is preferable. is there. When the catalyst B component is also used, it can be mixed at a ratio of 1 to 99 mol%, preferably 2 to 98 mol%.

The catalyst C component according to the present invention is platinum,
At least one noble metal selected from the group consisting of palladium, rhodium, ruthenium, and iridium or a compound thereof, and among these components, at least one of platinum and palladium having a high activity of decomposing ammonia and organic compounds is preferable. When the catalyst B component is also used, it can be mixed at a ratio of 1 to 99 mol%, preferably 2 to 98 mol%.

The above ratio of the components A, B and C is preferably 70 to 99% by weight in the form of oxide of the component A.
More preferably 75 to 95% by weight, the catalyst B component is 0.5 to 30% by weight in the form of an oxide, more preferably 1 to 20% by weight, and the catalyst C component is 0.001 to 5% by weight as a metal.
More preferably, it is in the range of 0.005 to 2.5% by weight.

When the amount of the component A of the catalyst is less than 70% by weight, the activity of decomposing ammonia and organic compounds is low, and when it exceeds 99% by weight, the activity of decomposing ammonia and organic compounds is also low. is there.

When the content of the catalyst B component is less than 0.5% by weight, the activity of decomposing ammonia and organic compounds at high temperature becomes low, and even if it is added in an amount of more than 30% by weight, a large activity of decomposing ammonia and organic compounds is obtained. This is because there is no improvement.

When the content of the catalyst component C is less than 0.001% by weight, the activity of decomposing ammonia and organic compounds at low temperature is low, and when it exceeds 5% by weight, NO at high temperature is obtained.
It is not preferable because x production increases.

The physical properties of the obtained catalyst are, as described in the physical properties of the catalyst A component, for example, if the BET surface area is too low, the activity of decomposing ammonia and organic compounds is low and the durability is lowered, so that it is 30 m2 / g or more. It is preferable that the amount is 40 m @ 2 / g or more. Further, if the pore volume is too low, the catalyst activity will be low, and if it is too high, the strength of the catalyst generally prepared will be low, so that it is preferably in the range of 0.25 to 0.9 cc / g, and 0.3 to 0. It is more preferably in the range of 0.7 cc / g. If it is less than 0.25 cc / g, the catalytic activity will be low, and if it is more than 0.9 cc / g, the catalyst strength will be reduced, and problems such as filling of the catalyst will occur.

Further, the volume of pores having a pore diameter of 0.5 μm or more is 0.05 to 0.6 with respect to the total pore volume.
The ratio is preferably in the range of 0.1 to 0.5, more preferably 0.1 to 0.5. If it is less than 0.05, the decomposition activity of ammonia and organic compounds will be low, and if it exceeds 0.6, the strength of the catalyst will be reduced, which is not preferable.

Below, TiO 2 --SiO 2 was used as the catalyst A component.
An example of a method for preparing a catalyst of the present invention, which comprises a composite oxide, vanadium and tungsten oxide as a catalyst B component, and palladium as a catalyst C component, will be shown.

First, TiO 2 -S obtained by the above method
A monoethanolamine aqueous solution of ammonium metavanadate and ammonium paratungstate and a molding aid such as starch and polyethylene oxide are added to the iO2 composite oxide powder and sufficiently kneaded, followed by extrusion molding into a honeycomb type. At this time, it is possible to add glass fiber or glass powder to increase the catalyst strength. Then, this molded body is 5
After drying at 0 ~ 150 ℃, 1 ~ 10 at 300 ~ 700 ℃
Bake for an hour. The honeycomb molded body thus obtained is impregnated with an aqueous solution of palladium nitrate, dried at 50 to 200 ° C. and calcined to obtain a desired catalyst.

As the gas to be subjected to the decomposition treatment of ammonia and organic compounds in which the catalyst of the present invention is used, organic substances such as human waste / livestock excrement, activated sludge, food waste, agricultural wastes and garbage, sewage treatment activated sludge, etc. There are gases emitted from the treatment facilities for toxic waste. These gases have characteristics of the catalyst obtained by the present invention, that is, high ammonia and organic compound decomposing activity in a wide temperature range from low temperature to high temperature, extremely low production of nitrogen oxides, and a treatment gas containing a sulfur compound. However, it is particularly preferably selected as a gas to be treated in order to make full use of the characteristics having excellent durability.

The catalyst of the present invention is used together with ammonia and an organic compound to form a sulfur oxide, hydrogen sulfide, a sulfur-containing organic compound,
When applied to a gas containing at least one compound selected from nitrogen-containing organic compounds, a decomposition treatment effect superior to the conventional one can be obtained. That is, hydrogen sulfide, sulfur-containing organic compounds, and nitrogen-containing organic compounds that are contained together with ammonia and organic compounds are easily decomposed together with ammonia and organic compounds by the catalyst of the present invention, and the durability of the catalyst is also high. In this case, sulfur oxides such as sulfur dioxide are contained as components together with ammonia and organic compounds, and sulfur-containing organic compounds other than hydrogen sulfide include methyl mercaptan, methyl sulfide, and methyl disulfide. Examples of the gas include amines such as trimethylamine and the like, and the effects of the present invention are remarkably exhibited.

There are no particular restrictions on the concentrations of ammonia and organic compounds used in the catalyst of the present invention, but when the concentration is high, it may be diluted with air or the like and passed through the catalyst.
The concentration at the catalyst inlet is 0.1-10000 ppm (volume) of ammonia, preferably 0.5-8000 ppm (volume),
0.01-10000ppmc (capacity), preferably 0.05-8000ppmc
(Capacity). An organic compound contains one or more C (carbon) in the molecule, and ppmc is a numerical value obtained by multiplying the concentration of the organic compound by the C number when there are plural Cs. Further, even if carbon monoxide is contained, it can be treated. It is not necessary to apply the method of the present invention insofar as the concentrations of these harmful substances can be released into the atmosphere as they are.

The concentration of hydrogen sulfide or sulfur-containing organic compound contained together with ammonia and the organic compound is
It is preferably in the range of 0 to 5000 ppm. Fifty
This is because if it exceeds 00 ppm, the catalytic activity is lowered.

The concentration of the nitrogen organic compound contained together with the ammonia and the organic compound is preferably in the range of 0 to 1%, and if it exceeds 1%, NOx production increases if it is too high. The concentration is preferably lower than the ammonia concentration in order to suppress the generation of NOx and increase the decomposition efficiency of ammonia and organic compounds, and further nitrogen-containing organic compounds. Usually, oxygen is excessively present in the gas to be treated with respect to ammonia and an organic compound, and further to the nitrogen organic compound portion, so that it is not particularly necessary to add oxygen, but the number of moles of the ammonia and the organic compound, and further the nitrogen-containing organic compound. When it is present at extremely low concentration, ammonia and organic compounds, and nitrogen-containing organic compounds are decomposed into nitrogen gas (N2), carbon dioxide gas (CO2) and water (H2O) more than twice the required amount. Addition is preferable because the decomposition efficiency is improved. If oxygen is present in a very large excess with respect to the number of moles of ammonia, organic compounds, and nitrogen organic compounds, the amount of NOx produced increases, so the oxygen concentration is 21
% Or less is preferable.

Space for the gas to be treated relative to the catalyst of the present invention
The speed is 100 to 100,000 hr ^-1, Preferably 50
0-50000hr^-1It should be in the range of. 100h
r^-1If it is less than, the processing equipment becomes too large and ineffective.
Because it is efficient, 100,000 hr^-1When exceeds
The reason is that if it is too high, the decomposition efficiency decreases.

When the catalyst of the present invention cannot be used to sufficiently decompose a hardly decomposable organic compound, it is possible to install an ordinary noble metal oxidation catalyst after the catalyst of the present invention, if necessary. . Examples of the hardly decomposable organic compound include saturated hydrocarbons such as methane, ethane and propane.
A commonly used precious metal catalyst may be a widely used precious metal catalyst. For example, a catalyst containing the following components A and B may be mentioned. Component A: an oxide of at least one metal selected from aluminum, titanium, silicon, cerium and iron, and component B: at least one metal or oxide selected from platinum, palladium, iridium, rhodium and ruthenium.

As described above, the reason why the noble metal catalyst is installed after the catalyst of the present invention is that the catalyst of the present invention is first used to oxidize and decompose other than organic compounds which are hardly decomposed, and after decomposing ammonia into nitrogen and water. The reason for this is that by passing it through, it is possible to decompose the hardly-decomposable organic compound and suppress the production of nitrogen oxides. On the contrary, if the noble metal catalyst is installed in the front stage and the catalyst of the present invention is installed in the rear stage, ammonia is oxidized by the noble metal catalyst and a large amount of nitrogen oxide is generated, which is not preferable. Further, when the inlet temperature of the noble metal oxidation catalyst is not sufficient, it is possible to raise the temperature between the catalyst of the present invention and the noble metal oxidation catalyst to 350 ° C. or higher and pass the noble metal oxidation catalyst.

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0046]

EXAMPLE (Example 1) A binary complex oxide composed of Ti and Si was prepared by the method described below. Snowtex-20 (manufactured by Nissan Chemical Industries, silica sol, containing about 20% by weight SiO2) in 700 liters of 10% by weight ammonia water 3
After adding 5.5 Kg and stirring and mixing, a sulfuric acid aqueous solution of titanyl sulfate (25 g / liter as TiO2, sulfuric acid concentration of 0.1).
300 liters (55 kg / liter) was gradually added dropwise with stirring. The obtained gel was left standing for 3 hours, washed with filtered water, and then dried at 150 ° C. for 10 hours. Then 500
It was calcined at ℃ for 6 hours. The composition of the obtained powder is Ti: Si
= 4: 1 (molar ratio), the BET surface area was 210 m2 / g. The X-ray diffraction chart of the powder thus obtained is T
No clear specific peaks of iO2 and SiO2 are observed, and T having a fine amorphous structure due to a broad diffraction peak.
It was confirmed to be a composite oxide composed of i and Si. 20 kg of the composite oxide powder composed of Ti and Si thus obtained was added with 0.56 K of ammonium metavanadate.
g, and 12 kg of a 10% aqueous monoethanolamine solution containing 1.79 kg of ammonium paratungstate, starch was further added as a molding aid and mixed, and the mixture was kneaded with a kneader.
It was formed into a honeycomb shape having a thickness of 8 mm, a thickness of 0.5 mm and a length of 500 mm. Then, it was dried at 80 ° C. and then baked at 450 ° C. for 5 hours in an air atmosphere. The composition of the obtained honeycomb formed body was
Ti-Si composite oxide: V2O5: WO3 = 91: 2: 7
(Weight ratio). This molded body was impregnated with an aqueous palladium nitrate solution (18 g-Pd / liter) for 1 minute and then 150
It was dried at 3 ° C for 3 hours and then calcined at 450 ° C for 3 hours in an air atmosphere. The BET surface area of the catalyst thus obtained is 13
It was 0 m2 / g and the pore volume was 0.45 cc / g. The volume of pores having a pore diameter of 0.5 μm or more is 0.11 cc / g (0.
24 ratio). The composition of the catalyst was as follows: Ti-Si composite oxide: V2O5: WO3: Pd = 90.8: 2.0: 7.
It was 0: 0.4 (weight ratio). Using this catalyst, a decomposition reaction of ammonia and an organic compound was carried out under the reaction conditions shown below.

Test target gas: ammonia: 4000 ppm, acetaldehyde: 10 ppm, butyric acid: 2 ppm, H2S: 10 ppm, H2
O: 10%, O2: 10 %, N2: balance reaction conditions: catalyst layer inlet temperature: 350 ° C., space velocity: 4000 hr ^-1 As a result, ammonia catalyst outlet: 1 ppm or less, NO _X: 12pp
m, acetaldehyde: 0.1 ppm or less, H2S: 0.02 ppm or less, butyric acid: 0.01 ppm or less. (Example 2) The same operation as in Example 1 was carried out except that the silica sol was not used to obtain a TiO2 powder. The BET surface area of the obtained powder is 75 m2 /
It was g. The powder thus obtained, ammonium metavanadate and ammonium paratungstate were mixed with TiO 2.
A slurry was prepared so that 2: V2O5: WO3 = 91: 2: 7, and 100 g of the cordierite carrier having 210 cells / inch ² was loaded per liter. A catalyst was prepared by further supporting 3 g of Pd on 1 liter of the supported catalyst. Using this catalyst, the gas to be tested is under the same conditions as in Example 1, and the reaction conditions are a catalyst layer inlet temperature of 350 ° C.,
The decomposition reaction of ammonia and organic compounds was carried out at a space velocity of 5000 hr ^-1 . As a result, ammonia: 5pp at the catalyst outlet
m, NO _X : 80ppm, acetaldehyde: 0.1ppm or less, H2S:
0.02ppm or less, butyric acid: 0.01ppm or less. (Comparative Example 1) γ-alumina was added to a cordierite carrier consisting of 210 cells / inch ^{2 with} 100 g of Pt per liter of catalyst and Pt.
An oxidation catalyst supporting 2 g was prepared. Using this catalyst, the gas to be tested was the same as in Example 1, and the reaction conditions were ammonia and organic compound decomposition reaction at a catalyst layer inlet temperature of 300 ° C. and a space velocity of 20000 hr ⁻¹ . As a result, ammonia at the catalyst outlet: 1 ppm or less, NO _X : 2000 ppm, acetaldehyde: 0.1 ppm or less, H2S: 0.02 ppm or less, butyric acid: 0.0
It fell below 1 ppm.

[0048]

EFFECTS OF THE INVENTION By using the catalyst of the present invention, a high activity of decomposing ammonia and organic compounds is exhibited, a high selectivity to nitrogen and water, NOx production is extremely low, and a gas containing ammonia and organic compounds is treated. Is possible. Moreover, when a gas containing at least one compound selected from hydrogen sulfide, sulfur-containing organic compounds and nitrogen-containing organic compounds together with ammonia and organic compounds is decomposed using the ammonia and organic compound decomposition catalyst of the present invention, only ammonia and organic compounds are decomposed. Alternatively, these coexisting compounds can be decomposed with high efficiency at the same time. According to the present invention, highly efficient decomposition treatment of gas discharged from treatment facilities etc. to organic waste such as human waste / livestock excrement, activated sludge, food waste, agricultural waste, sewage treatment activated sludge and raw waste is achieved. .

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D048 AA08 AA17 AA19 AB01 AB03                       AB05 BA06X BA07X BA23X                       BA26Y BA27X BA30Y BA31X                       BA32Y BA33Y BA41X BA42X                       BB02 BC01 CC38 DA03 DA06                 4G069 AA03 AA08 BA04A BA04B                       BB04A BB04B BB06A BB06B                       BC50A BC50B BC51A BC54A                       BC54B BC59A BC60A BC60B                       BC70A BC71A BC72A BC72B                       BC74A BC75A BD05A BD05B                       CA04 CA07 CA10 CA11 DA06                       EA02Y EA19 FA01 FA02                       FB14 FB67

Claims (6)

[Claims] 1. A catalyst A component which is an oxide containing Ti, a catalyst B component which is an oxide of at least one metal selected from the group consisting of vanadium, tungsten and molybdenum, platinum, palladium, rhodium, A catalyst for simultaneous oxidative decomposition of ammonia and an organic compound, which comprises at least one noble metal selected from the group consisting of ruthenium and iridium or a catalyst component C which is a compound thereof. 2. A binary complex oxide containing Ti and Si as a catalyst A component; a binary complex oxide containing Ti and Zr; and a ternary complex oxide containing Ti, Si and Zr. The catalyst for simultaneous oxidative decomposition of ammonia and an organic compound according to claim 1, wherein at least one complex oxide is used. 3. A method for simultaneous oxidative decomposition of ammonia and an organic compound using the catalyst according to claim 1. 4. A gas containing ammonia and an organic compound and at least one compound selected from the group consisting of sulfur oxides, hydrogen sulfide, sulfur-containing organic compounds and nitrogen-containing organic compounds, and the gas according to claim 1 or 2. A method for simultaneous oxidative decomposition of ammonia and organic compounds using a catalyst. 5. The method for simultaneous oxidative decomposition of ammonia and an organic compound according to claim 3, wherein the gas temperature of the gas containing ammonia and the organic compound is controlled to 280 ° C. to 400 ° C. and introduced into the catalyst layer. 6. A gas containing ammonia and an organic compound, which is generated when carbonizing an organic waste such as human waste / livestock excrement, activated sludge, food waste, agricultural waste and raw garbage, and sewage treatment activated sludge. A method for simultaneous oxidative decomposition of ammonia and an organic compound according to any one of claims 3 to 5.