JP2916259B2 - Method for oxidative decomposition of organic halogen compounds - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for oxidatively decomposing an organic halogen compound contained in exhaust gas generated from various processes such as an incinerator and various cleaning processes, and further relates to a method for oxidizing and decomposing carbon monoxide. The present invention relates to a method for oxidatively decomposing an organic halogen compound, which can prevent the generation of nitrogen oxides and carbon monoxide contained in the exhaust gas at the same time.

BACKGROUND ART As methods for treating harmful organic halogen compounds contained in exhaust gas and the like, there are known a method of directly burning under a temperature condition of 800 ° C. or higher, and a method of removing the harmful organic halogen compound by adsorbing it on an adsorbent such as activated carbon.

However, the former direct combustion method is not economical because it requires a large amount of fuel, and it has problems such as release of highly toxic halogen elements and decomposition of carbon monoxide depending on operating conditions. I have. On the other hand, the method using an adsorbent such as activated carbon has a problem that the adsorption efficiency varies depending on the concentration of the substance to be treated, and the coexisting substance inhibits the adsorption efficiency.

Also, a method of oxidative decomposition using an oxide of a transition metal element as a catalyst (JP-A-51-22699, JP-A-3-47516)
Although it has been developed and can perform oxidative decomposition treatment under relatively low temperature conditions, it has problems that the complete oxidation rate is low and harmful carbon monoxide remains in the processing gas.

The present invention has been made focusing on the above circumstances,
Oxidative decomposition of organic halogen compounds that can efficiently oxidize and decompose organic halogen compounds under low temperature conditions without generating harmful chlorine gas, etc., and can simultaneously remove nitrogen oxides and carbon monoxide contained in exhaust gas. It is intended to provide a processing method.

DISCLOSURE OF THE INVENTION The oxidative decomposition treatment method of an organic halogen compound according to the present invention comprises a catalyst A component containing a composite oxide composed of two or more metals selected from the group consisting of Si, Ti and Zr; V, Mo, Sn, Ce and W using a catalyst containing one or more metal oxides selected from the group consisting of W, the above exhaust gas under a temperature condition of 150 ~ 600 ℃ The gist of the invention is to make the catalyst react in a catalytic manner.

Further, Cr, Mn, Fe, Cu, Ru, R
one or two selected from the group consisting of h, Pd, Pt and Au
If at least one kind of metal or metal oxide is contained, generation of carbon monoxide can be prevented. If ammonia gas is added to the exhaust gas, organic halogen compounds and carbon monoxide contained in the exhaust gas are oxidized and nitrogen is added. It is possible to remove oxides.

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors use a composite oxide composed of two or more metals selected from the group consisting of Si, Ti and Zr as a catalyst A component, and use V, By using oxides of Mo, Sn, Ce and W, organic halogen compounds can be efficiently oxidatively decomposed even under a low temperature condition of 150 to 600 ° C, and Cr, Mn, Fe, Cu, Ru, Rh can be used as a catalyst C component. , Pd, Pt, and Au were found to be able to suppress the production of carbon monoxide as much as possible if used in combination with one or more metals or metal oxides selected from the group consisting of Au. I arrived.

Further, according to the method of the present invention, by adding ammonia gas to exhaust gas, organic halogen compounds and carbon monoxide can be oxidized and decomposed, and nitrogen oxides can be removed.

 Hereinafter, the present invention will be described in detail.

The organic halogen compound targeted by the present invention may be any organic compound having at least one halogen atom in the molecule, such as methyl chloride, ethyl chloride,
Aliphatic organic chlorine compounds such as dichloroethylene and vinyl chloride; aliphatic organic bromine compounds such as methyl bromide, methylene bromide, ethylene bromide and vinyl bromide; monochlorobenzene;
Aromatic organic chlorine compounds such as dichlorobenzene; aromatic organic bromine compounds such as benzyl bromide and benzylidene bromide; toxic organic chlorine compounds such as polychlorinated dibenzodioxins and polychlorinated benzofurans; and trichlorofluoromethane and dichlorodifluoromethane Freon gas and the like can be exemplified.

In the case where a solid organic chlorine compound such as PCB or 2,4,5-trichlorophenoxyacetic acid is burned without a catalyst, the present invention may be applied to exhaust gas after burning.

Oxygen-containing gas used in the present invention is to oxidize the organic halogen compound, the carbon in the organic halogen compound is converted to CO _2, have a sufficient amount of oxygen to convert the halogen element HCl, HBr, in HF or the like Any air may be used, and normal air or air with an increased oxygen concentration may be used.

The catalyst A component used in the present invention includes at least Si, T
Preferred results can be obtained as long as it contains a composite oxide composed of two or more metals selected from the group consisting of i and Zr. For example, binary composite oxides such as titanium-silicon and titanium-zirconium can be obtained. And ternary composite oxides such as titanium-silicon-zirconium.

Since these binary or ternary composite oxides have a large surface area as compared with the single oxide, the catalyst B component, which is an active component in the oxide decomposition reaction according to the method of the present invention, and Excellent dispersibility of catalyst C component and high activity,
In addition, it has excellent acid resistance, and HC coexists in the processing gas.
It is possible to maintain long-term activity without being affected by acidic gases such as l and SOx.

Further, the composition of the catalyst according to the present invention is as follows.
Preferably, the components are in the range of 70-95% by weight, the catalyst B component in the range of 0.1-20% by weight, and the catalyst C component in the range of 0.01-25% by weight. If the amount of the catalyst B component exceeds 20% by weight, the strength of the catalyst will be weakened, and long-term use will be affected. Therefore, the content of the catalyst B component is preferably in the range of 0.1 to 20% by weight. If the amount of the catalyst C component is more than 20% by weight, the raw material cost of the catalyst is increased, which is not preferable. On the other hand, if the amount is less than 0.01% by weight, carbon monoxide is generated. In addition, HCl, H generated by using the catalyst
F, HBr and the like can be easily removed by a known method such as alkali washing.

 Next, a typical method for preparing the catalyst of the present invention will be described below.

To a composite oxide containing titanium-silicon, titanium-zirconium and titanium-silicon-zirconium, etc., add an aqueous solution or oxide powder containing a catalyst B component such as V, W, etc. together with a molding aid and add an appropriate amount of water. While mixing, kneading, and forming on a honeycomb by an extruder. The molded product is dried at 50 to 120 ° C. and calcined at 400 to 600 ° C., preferably 430 to 550 ° C. for 1 to 10 hours, preferably 2 to 6 hours, in an air stream to obtain a molded product.

The molded product thus obtained is added to the catalyst C component, that is, a noble metal catalyst substance such as Ru, Rh, Pd, Pt, or Au, or Cr, Mn, Fe, Cu.
Are carried as a metal or an oxide thereof to obtain a finished catalyst. As the catalyst C component, metals of the periodic table VIII are particularly preferably used. Among them, Ru, Rh,
Pd and Pt are preferable, and Au is also preferable.

As a method of supporting the catalyst C component on the molded product, the molded product is immersed in an aqueous solution of the catalyst C component at room temperature for 1 to 5 minutes, dried at 30 to 200 ° C, preferably 70 to 170 ° C, and then air The firing may be performed at a temperature of 300 to 700 ° C, preferably 400 to 600 ° C.

The shape of the catalyst is not limited to the above-described honeycomb shape, and may be appropriately selected from a columnar shape, a cylindrical shape, a plate shape, a ribbon shape, a corrugated plate shape, a pipe shape, a donut shape, a lattice shape, and other integrally formed shapes. It is also possible to coat a molded carrier such as cordierite or mullite with a slurry composed of the catalyst A component and the B component, and further impregnate the catalyst C component into a catalyst.

The silicon raw material used in preparing the catalyst of the present invention can be selected from colloidal silica, water glass, inorganic silicon compounds such as silicon tetrachloride, and ethyl silicates. The titanium raw material can be selected from inorganic titanium compounds such as titanium chlorides, titanium hydroxide, and titanium sulfate, and organic titanium compounds such as titanium oxalate and tetraisopropyl titanate.
The zirconium source can be selected from inorganic zirconium compounds such as zirconium chloride, zirconium oxychloride, and zirconium nitrate, and organic zirconium compounds such as zirconium oxalate and tetraisopropyl zirconate.

As the starting material of the catalyst B component, oxides, hydroxides, inorganic salts, organic salts and the like may be appropriately selected, and examples thereof include ammonium salts, oxalates, sulfates and halides. On the other hand, the starting material of the catalyst C component is appropriately selected from chlorides, nitrates, organic acid salts, noble metal chloride acids, and copper compounds.

In the present invention, the type of the reactor is not limited, and an ordinary reactor such as a fixed bed, a moving bed, or a fluidized bed can be applied. In addition, when the organic halogen compound in the exhaust gas from the incinerator is targeted, the amount of dust is large, and the catalyst layer may be clogged. In such a case, a honeycomb catalyst that can adjust the aperture according to the amount of dust is used. Filling is preferred.

The reaction temperature is preferably in the range of 150 to 600 ° C. If the temperature is lower than 150 ° C, sufficient decomposition efficiency cannot be obtained.

Examples Example 1 A composite oxide composed of titanium and silicon was prepared by the method described below. An aqueous solution of titanyl sulfate in sulfuric acid having the following composition was used as a titanium source.

TiOSO ₄ (TiO ₂ equivalent) 250 g / liter Total H ₂ SO ₄ 1100 g / liter Separately, add 286 liters of ammonia water (NH ₃ , 25%) to 400 liters of water, and add Snowtex-NCS-30 (Nissan Chemical) sol about 30 wt% content as SiO ₂₎ 24 kg
Was added. To the obtained solution, 153 liters of the above-mentioned aqueous solution of titanyl sulfate in sulfuric acid was added to 300 liters of water, and a diluted aqueous solution of titanium-containing sulfuric acid was gradually added dropwise with stirring to form a coprecipitated gel. Furthermore, it was left as it was for 15 hours. The thus obtained gel of the titanium-silicon composite oxide was filtered, washed with water and dried at 200 ° C. for 10 hours.

Then, it was fired at 550 ° C. for 6 hours in an air atmosphere. The composition of the obtained powder was Ti: Si = 4: 1 (atomic ratio), and the BET surface area was 185 m ² / g. The powder obtained hereafter was referred to as TS-1 and a molded article was prepared using the powder by the method described below.

0.7 liter of monoethanolamine is mixed with 7 liters of water, and 1.03 kg of ammonium paratungstate is added.
To dissolve, then ammonium metavanadate 1.
Dissolve 14 kg to make a uniform solution. The solution was further mixed and kneaded while adding an appropriate amount of water with a kneader in addition to the above TS-1: 16 kg, and then extruded with an extruder to have an outer shape of 80 mm square, an aperture of 3.0 mm, a wall thickness of 0.7 mm, and a length of 350 mm. It was formed into a lattice. Next, after drying at 60 ° C., it was calcined at 450 ° C. for 5 hours under flowing air. The composition of the obtained completed catalyst was TS-1: V ₂ O ₅ : WO ₃ = 90: 5: 5 in terms of weight ratio as an oxide. The catalyst thus obtained has an outer diameter of 23 mm square (6 cells x 6 cells), length
It was cut into 300 mm and charged into a reactor, and a synthesis gas having the following composition was passed under angular conditions.

1-1 Decomposition of 1,1,2,2-tetrachloroethane Space velocity 2000h ^-1 Gas concentration 300ppm / air balance Temperature condition 250,300,350 ℃ 1-2 Decomposition of dichlorobenzene Space velocity 2000h ^-1 Gas concentration 300ppm / air balance Temperature condition 200,250,300,350 ℃ 1-3 Decomposition of Freon 113 Space velocity 2000h ^-1 Gas concentration 500ppm / air balance Temperature condition 300,350,400 ℃ Table 1 shows the results obtained by the above test.

In each case, Cl ₂ gas was not detected in the post-treatment gas.

Example 2 A compact (TS-1: V ₂ O ₅ : WO ₃ = 90: 5: 5) obtained by using the TS-1 powder obtained in Example 1 and in the same manner as in Example 1 was used. ,
Immersion in 3.0 liters of platinum chloride aqueous solution containing 22.1 g of Pt for 1 minute, followed by drying at 100 ° C.
It was baked at 50 ° C. for 5 hours. The Pt carrying amount of the obtained catalyst was 0.25.
% By weight.

The above catalyst has an outer diameter of 23mm square (6 cells x 6 cells), length 300m
After cutting into m, the reactor was filled and subjected to a decomposition test of 1,1,2,2-tetrachloroethane, dichlorobenzene and Freon 113 under the same conditions as in Example 1. The results are shown in Table 2. In each case, Cl ₂ gas was not detected in the post-treatment gas.

Example 3 A molded article (TS-1: V ₂ O ₅ : WO ₃ = 90: 5: 5) obtained by using the TS-1 powder obtained in Example 1 and in the same manner as in Example 1 was used. ,
It was immersed in 3.0 liters of an aqueous palladium nitrate solution containing 11.0 g of Pd for 1 minute, dried at 100 ° C., and then baked at 500 ° C. for 2 hours under flowing air. The amount of Pd supported on the obtained catalyst was 0.1% by weight.

The above catalyst has an outer diameter of 23mm square (6 cells x 6 cells), length 300m
The resulting mixture was cut into m, filled into a reactor, and subjected to a decomposition test of 1,1,2,2-tetrachloroethane, dichlorobenzene and Freon 113 under the same conditions as in Example 1. The results are shown in Table 3. In each case, Cl ₂ gas was not detected in the post-treatment gas.

Example 4 Using the TS-1 powder obtained in Example 1, TS-1: V ₂ O ₅ : W
A molded article of O ₃ = 87: 8: 5 (weight ratio) was prepared according to Example 1. The molded body is 80mm square, aperture 3.0mm, wall thickness 0.7mm, length
It is a 350mm grid. Chromium nitrate [Cr (NO ₃ ) ₃
[9H ₂ O] 1 in an aqueous solution of 170 g dissolved in 3.0 liters of water
After immersion for 100 minutes and then drying at 100 ° C., it was baked at 500 ° C. for 2 hours under flowing air. The supported amount of the obtained catalyst as Cr ₂ O ₃ was 0.38% by weight.

The above catalyst has an outer diameter of 23mm square (6 cells x 6 cells), length 300m
m and cut into a reactor, and subjected to a decomposition test of dichlorobenzene under the same conditions as in Example 1. The results are shown in Table 4. No Cl ₂ gas was detected during the reaction.

Example 5 TS-1: V ₂ O ₅ : WO ₃ = 87 having the same composition and size as Example 4
A molded body of 8: 5 (weight ratio) was prepared. This was immersed in an aqueous solution obtained by dissolving 1370 g of manganese nitrate [Mn (NO ₃ ) ₂ .6H ₂ O] in 3.0 liters of water for 1 minute, then dried at 100 ° C. and then calcined at 500 ° C. for 2 hours under flowing air. . The supported amount of the obtained catalyst as MnO ₂ was 5% by weight.

Using the above catalyst, a decomposition test of dichlorobenzene was conducted in the same manner as in Example 4. The results are shown in Table 4.
No Cl ₂ gas was detected during the reaction.

Example 6 TS-1: V ₂ O ₅ : WO ₃ = 87 having the same composition and size as Example 4
A molded body of 8: 5 (weight ratio) was prepared. This is converted to copper nitrate [Cu
1270 g of (NO ₃ ) ₂ .3H ₂ O] was immersed in an aqueous solution of 3.0 liters of water for 1 minute, dried at 120 ° C., and calcined at 500 ° C. for 2 hours under flowing air. The supported amount of the obtained catalyst as CuO was 5% by weight.

Using the above catalyst, a decomposition test of dichlorobenzene was conducted in the same manner as in Example 4. The results are shown in Table 4.
No Cl ₂ gas was detected during the reaction.

Example 7 TS-1: V ₂ O ₅ : WO ₃ = 87 having the same composition and size as Example 4
A molded body of 8: 5 (weight ratio) was prepared. This as Pd 22.
Immersed in 3.0 liters of palladium nitrate aqueous solution containing 0 g for 1 minute, then dried at 100 ° C.
For 2 hours. The amount of Pd supported on the obtained catalyst was 0.25% by weight.

The above catalyst has an outer diameter of 23mm square (6 cells x 6 cells), length 300m
and filled cut into reactor m, nitrogen monoxide, carbon monoxide, and NH ₃ was added as a reducing agent to a gas including dichlorobenzene and SO _2, simultaneous processing of nitric oxide, carbon monoxide and dichlorobenzene Tested. The gas conditions and reaction conditions are as follows.

1. Gas Conditions dichlorobenzene 30 ppm v / v NO 300 ppm v / v NH 3 300 ppm v / v CO 1.0 vol% SO 2 100 ppm v / v H 2 O 10 vol% AIR balance 2. Space velocity 2000h ^-1 3. Reaction temperature 200,250 ° C The results are shown in Table 5.

Example 8 Water 500 liters in zirconium oxychloride (ZrOCl ₂ · 8
19.3 kg of H ₂ O) was dissolved, and 78 liters of an aqueous sulfuric acid solution of titanyl sulfate having the same composition as that used in Example 1 was added and mixed well. While maintaining the mixed aqueous solution at about 30 ° C., ammonia water was gradually added dropwise until the pH reached 7 while stirring well, and the mixture was allowed to stand for further 15 hours. The obtained gel was filtered, washed with water and dried at 200 ° C. for 10 hours. Then, the mixture was fired at 550 ° C. for 5 hours in an air atmosphere to obtain a titanium-zirconium composite oxide. The composition of the obtained composite oxide powder was Ti: Zr = 4: 1 (atomic ratio), and the BET surface area was 140 m ² / g. The powder obtained here is hereinafter referred to as TZ-1. Using this TZ-1, in the same manner as in Example 1, a molded product of TZ-1: V ₂ O ₅ : WO ₃ = 90: 5: 5 (weight ratio) (80 mm square, mesh opening 3.0 mm, wall thickness) 0.7 mm, length 350 mm). The molded body was immersed in 3 liters of an aqueous solution of platinum chloride containing 11.0 g of Pt for 1 minute, dried at 120 ° C., and calcined at 450 ° C. for 2 hours under flowing air to obtain a completed catalyst. The amount of Pt supported on the obtained catalyst is 0.1% by weight.
Met.

This catalyst was treated in the same manner and under the same conditions as in Example 7 by adding NH ₃ as a reducing agent to a gas containing nitrogen monoxide, carbon monoxide, dichlorobenzene and SO ₂ , and then nitric oxide, carbon monoxide and dichlorobenzene were added. Was tested simultaneously. The results are shown in Table 6.

Comparative Example 1 A cordierite honeycomb carrier having a pore size of 3 mm square
-Alumina powder is coated, dried and calcined to prepare a catalyst support, Pt is supported on the catalyst support by a chemisorption method, dried at 100 ° C, and then dried under air flow.
Calcination at 50 ° C. for 2 hours gave a comparative catalyst. The Pt carrying amount of the catalyst was 0.25% by weight. Using this catalyst, a decomposition test of 1,1,2,2-tetrachloroethane and dichlorobenzene was performed under the same conditions as in Example 1. The results are shown in Table 7.

Comparative Example 2 1.5 kg of water was added to 10 kg of commercially available TiO ₂ powder (BET surface area: 30 m ² / g), and the mixture was kneaded well.
Formed into a grid of 3.0mm, 0.7mm thickness, 350mm length, 60 ℃
And calcined at 450 ° C. for 5 hours under flowing air.
Aqueous platinum chloride solution 3 containing 14 g of Pt
It was immersed in a liter for 1 minute, dried at 100 ° C., and baked at 450 ° C. for 5 hours under flowing air. The amount of Pt supported on the obtained catalyst was 0.12% by weight. The catalyst was cut into the same dimensions as in Example 1 and subjected to a decomposition test of 1,1,2,2-tetrachloroethane and dichlorobenzene under the same conditions. The results are shown in Table 8.

Comparative Example 3 0.7 liter of monoethanolamine was mixed with 7 liters of water, and 1.03 kg of ammonium paratungstate was added and dissolved, and then ammonium metavanadate 1.14 was further added.
kg was dissolved to obtain a homogeneous solution. This solution was added to 16 kg of the same TiO ₂ powder as used in Comparative Example 2 and kneaded well while adding an appropriate amount of water.
m, a thickness of 0.7 mm, and a length of 350 mm were formed into a lattice, dried at 60 ° C., and fired at 450 ° C. for 5 hours under flowing air. The composition of the obtained catalyst is as follows: TiO ₂ : V ₂ O ₅ :
WO ₃ = 90: 5: 5. This molded body was immersed in 3 liters of an aqueous solution of platinum chloride containing 45 g of Pt for 1 minute, dried at 100 ° C., and baked at 450 ° C. for 5 hours under flowing air. The amount of Pt supported on the obtained catalyst was 0.31% by weight. The above catalyst was treated in the same manner and under the same conditions as in Example 7 by adding NH ₃ as a reducing agent to a gas containing nitrogen monoxide, carbon monoxide, dichlorobenzene and SO ₂ , and then adding nitrogen monoxide, carbon monoxide and dichlorobenzene. Was tested simultaneously. The results are shown in Table 9.

INDUSTRIAL APPLICABILITY Since the present invention is configured as described above, it is possible to oxidatively decompose an organic halogen compound and further produce harmful gases such as carbon monoxide and halogen gas as a by-product. The organic halogen compound can be efficiently treated under a low temperature condition without performing, and the oxidative decomposition treatment method of the organic halogen compound capable of removing nitrogen oxides and carbon monoxide together with the organic halogen compound contained in the exhaust gas. It can be provided.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-42015 (JP, A) JP-A-3-47516 (JP, A) JP-A-51-22699 (JP, A) JP-A-2- 229547 (JP, A) JP 1-14807 (JP, B2) JP 57-30532 (JP, B2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B01D 5/86 B01J 23 / 16,23 / 64

Claims (4)

(57) [Claims] 1. A method for oxidatively decomposing an organic halogen compound contained in an exhaust gas to detoxify an organic halogen compound, wherein the catalyst A component comprises at least two types selected from the group consisting of Si, Ti and Zr. Complex oxides composed of metals as oxides
A catalyst containing 70 to 95% by weight and containing, as a catalyst B component, an oxide of one or more metals selected from the group consisting of V, Mo, Sn, Ce and W; A method for oxidatively decomposing an organic halogen compound, wherein the exhaust gas is contacted with the catalyst under a temperature condition of 600 ° C. 2. A method for oxidatively decomposing an organic halogen compound contained in exhaust gas to render the organic halogen compound harmless, wherein the catalyst A component comprises at least two types selected from the group consisting of Si, Ti and Zr. Complex oxides composed of metals as oxides
The catalyst B component contains 0.1 to 20% by weight of an oxide of one or more metals selected from the group consisting of V, Mo, Sn, Ce and W as the catalyst B component. And one or more metals or metal oxides selected from the group consisting of Cr, Mn, Fe, Cu, Ru, Rh, Pd, Pt and Au as the catalyst C component; Oxidative decomposition of an organic halogen compound, wherein the exhaust gas is contacted with the catalyst under a temperature condition of 150 to 600 ° C. using a catalyst which is calcined at 400 to 600 ° C. containing 400% by weight. Method. 3. The method according to claim 2, wherein ammonia gas is added to the exhaust gas to remove nitrogen oxides and organic halogen compounds contained in the exhaust gas. 4. The method according to claim 2, wherein ammonia gas is added to the exhaust gas to remove nitrogen oxides, carbon monoxide and organic halogen compounds contained in the exhaust gas.