JPH11188260A - Catalyst for decomposition of organic chlorine compound and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a catalyst which lowers oxidizing and poisoning properties of SOx contained in waste gas and efficiently makes org. chlorine compds. harmless at a low temp. and a low cost. SOLUTION: This catalyst comprises a component (A) and a component (B) and the component B is 1-40 wt.% of the component A. The component A is a binary or ternary multiple oxide comprising titanium oxide (a) and zirconium oxide and/or silicon oxide (b) and (b) is 2-40 wt.% of (a). The component B is metal vanadium or vanadium oxide (c) and metal tungsten or tungsten oxide (d) and/or metl molybdenum or molybdenum oxide (e) and the weight ratio of (d) to (c) or that of (e) to (c) is <=10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for decomposing aliphatic and aromatic organic chlorine compounds and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a catalyst for decomposing dioxins as an organic chlorine compound, a catalyst in which vanadium pentoxide and tungsten trioxide are supported on a titanium oxide carrier has been known. It has been generally used as a catalyst for removing nitrogen oxides contained therein as a reducing agent for ammonia (Japanese Unexamined Patent Publication No.
No. 35914). As a decomposition catalyst for a halogen-containing organic compound, for example, an aliphatic organochlorine compound such as chlorofluorocarbon, trichlene, or perchrene, an acidic zeolite or a metal-substituted zeolite belonging to the second to sixth periods of the periodic table is known. (JP-A-4-250825)
Reference). Further, as a catalyst for decomposing organic halogen compounds such as methylene chloride and methyl bromide, TiO ₂ -Zr
A catalyst in which a noble metal (Pt, Pd) is supported on an O ₂ composite oxide carrier is known (Japanese Patent Application Laid-Open No. 8-173760).

[0003]

The above-mentioned catalyst utilizing a catalyst for removing nitrogen oxides contained in exhaust gas from a refuse incinerator using ammonia as a reducing agent has been proposed. ), The efficiency at which the temperature is 280 ° C. and the space velocity (SV) is 9600 h ⁻¹
Under such conditions, it was as low as 30 to 48%. Further, such a catalyst had inferior processing ability in a practically low concentration range. Further, in the case where the H-type mordenite-type zeolite used as an aliphatic organochlorine compound decomposition catalyst is replaced with Co, Cu, Ni, Fe, the removal efficiency of dichloromethane (CH ₂ Cl ₂ ) is 49-350 ° C. It was as low as 58%. Although such a catalyst is suitable for treating a halogen-containing organic compound having a relatively low molecular weight, there is no example of a polymer having a benzene ring. In addition, C generated by the reaction
The durability to acidic substances such as l ₂ , HCl and sulfur oxides present in the exhaust gas is poor, which is a problem. further,
P used as a decomposition catalyst for organic halogen compounds
In t · Pd / TiO ₂ —ZrO ₂ , methylene chloride (CH
_Although the decomposition rate of ₂ Cl ₂ ) is good at 71 ° C. to 88% at 350 ° C., the production cost of the catalyst is increased due to the use of a noble metal, and the durability to acidic substances is poor.

[0004] The present invention solves the above-mentioned problems, and the deterioration of the catalyst can be suppressed even if the exhaust gas contains an acidic substance which is the main cause of the deterioration of the catalyst, or the exhaust gas generated by the treatment affects the catalyst itself. Provided is a catalyst which can be used stably, is used at a low temperature of 150 to 300 ° C., has a high removal efficiency of an organic chlorine compound at that time, and has a low production cost and running cost of the catalyst, and a production method thereof. The purpose is to do so.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve such problems, and as a result, a composite oxide having a specific composition is used as a carrier, and a metal or metal oxide having a specific composition is used as a carrier. Have been found to be effective, and have reached the present invention.

That is, the first aspect of the present invention is the following A
Component and B component, and B component is 1 to 4 with respect to A component.
A gist of the present invention is a catalyst for decomposition treatment of an organic chlorine compound, which is characterized by being 0 wt%. (A): a binary or more composite oxide comprising (a) a titanium oxide and (b) a zirconium oxide and / or a silicon oxide, provided that (b) is 2 to 40% by weight based on (a) is there. (B): a composition comprising (a) a metal or metal oxide of vanadium, or (a) a composition comprising a metal or metal oxide of (b) tungsten and / or (c) a metal or metal oxide of molybdenum. Object, but
(B) or (c) has a weight ratio of 10 or less to (a). A second aspect of the present invention is the decomposition of an organochlorine compound according to the above catalyst, wherein the crystallinity of component (B), component (B) or component (C) in component (B) is 60% or less. The gist of the present invention is a treatment catalyst. . The third aspect of the present invention is:
It is a method for producing the above catalyst, in which the raw material of the component A is adjusted and dried, and then calcined in an air stream at 300 to 800 ° C. to prepare a composite oxide, which is impregnated with a solution containing the component B. A method for producing a catalyst is characterized in that it is dried and then calcined in an air stream at 300 to 800 ° C.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the first catalyst for decomposition treatment of an organic chlorine compound of the present invention will be described. The organic chlorine compounds in the present invention include dioxins such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), as well as monochlorobenzene, dichlorobenzene and o, which are precursors of these dioxins. -Chlorinated organic compounds such as chlorophenol are also included, and further, aliphatic organic chlorinated compounds such as Freon, trichlene, and perchrene are also included.

The catalyst of the present invention comprises A component and B component, and the B component needs to be 1 to 40 wt% with respect to the A component, and preferably 5 to 30 wt%. If the amount of the component B is too small relative to the component A, the activity as a catalyst will be low. If the amount is too large, the component will not be uniformly dispersed on the carrier composed of the component A, and will form aggregates, thereby reducing the pores of the carrier. It is not preferable because it causes blockage and lowers the activity.

The component A of the catalyst of the present invention is a binary or more complex oxide composed of (a) titanium oxide and (b) zirconium oxide and / or silicon oxide.
It is necessary that the content is 2 to 40% by weight based on (a), and preferably 5 to 20% by weight. Outside this range, molding is difficult and strength is reduced, and durability of the catalyst carrier becomes a problem.

Specific examples of the titanium oxide used in the present invention include TiO ₂ , TiO _2n-1 (n = 4 to 9), Ti ₂ O ₅ ,
₂ O ₃ and TiO. Of these, TiO ₂ having three types of modifications, rutile, brookite and anatase, is preferred, and anatase form is particularly preferred. Further, specific examples of the zirconium oxide used in the present invention include ZrO ₂ . Further, specific examples of the silicon oxide used in the present invention include SiO ₂ and SiO ₂ . Of these, SiO ₂ is preferred. In the present invention, the component A includes TiO ₂ and Si
O ₂ , since it is a composite oxide such as TiO ₂ and ZrO ₂ , TiO ₂ and SiO ₂ and ZrO ₂ , each oxide in the component A is not necessarily limited to the above crystal form, and Ti-O-Si, It is preferable to adopt an amorphous structure containing Ti-O-Zr and Zr-O-Si bonds.

The B component of the catalyst of the present invention may be (a) a composition comprising a metal or metal oxide of vanadium, or (b) a metal or metal oxide of (b) tungsten and / or (c) a molybdenum. It is a composition comprising a metal or a metal oxide, and (b) or (c) must have a weight ratio of 10 or less to (a). Preferably, it is 5 or less.

Specific examples of the vanadium metal or metal oxide in the present invention include VO, V ₂ O ₃ , VO ₂ , V ₂ O ₅ , V
_n O _2n-1 (n = 4 to 8) and V _n O _{2n + 1} (n = 3,6). Of these, V ₂ O ₅ is preferred. Specific examples of the tungsten metal or metal oxide in the present invention include WO
_{2, WO 3, W 18 O} 49, W 20 O 58, W 50 O 148, W 40 O 119 , and the like. Of these, WO ₃ is preferred. Specific examples of the metal or metal oxide of molybdenum in the present invention,
MoO ₂ , MoO ₃ , Mo ₃ O ₈ , Mo ₈ O ₂₃ , Mo ₉ O ₂₆ , Mo ₄ O ₁₁ , Mo ₁₇ O
_47, Mo ₅ O ₁₄ and the like. Of these, MoO ₃ is preferred.

The second catalyst for decomposition of an organochlorine compound of the present invention is a further catalyst (B) of the first catalyst of the present invention described above.
The crystallinity of (a), (b) or (c) in each component must be 60% or less. The crystallinity here is determined as follows. All V ₂ O ₅ metal in the B component, respectively, WO _3, X-ray theoretical diffraction intensity I _i, assuming that a crystalline oxide represented by MoO ₃ (i) is expressed by the following equation.

[0014]

(Equation 1)

I _ip is the X-ray diffraction intensity of the pure i component, (μ /
ρ) _i is the mass absorption coefficient of the i component, (μ ′ / ρ) is the average mass absorption coefficient of the sample, and W _i is the weight fraction of the i component in the sample. This is a value when the amount of metal is measured by ICP or the like and all detected metals are assumed to be crystalline oxides. Then, the X-ray diffraction intensity (I) of the i component of the sample is measured, and the crystallinity of the i component in the sample is defined as I / I _i .
The diffraction intensity is assumed to be an intensity appearing in a range of a diffraction angle (2θ) of 5 to 90 °, preferably 10 to 40 °.

The second catalyst of the present invention needs to have a crystallinity determined by the above formula of 60% or less, preferably 50% or less. Not all of the supported metals are supported in the form of crystalline oxides. That is, it is considered that the activity is high because the substance is present on the carrier in an energetically unstable state.

Next, the production method of the present invention will be described.
The raw material of the component A serving as the composite oxide carrier of the catalyst of the present invention is not particularly limited, but titania oxide is titania sol, titanium sulfate, titanium oxide chloride, titanium tetrachloride, titanyl sulfate, etc., and silicon oxide is water glass, Silica sol,
As the zirconium oxide such as sodium silicate and ethyl silicate, zirconia sol, zirconium oxide, zirconium chloride, zirconium sulfate, zirconium oxalate, zirconium oxychloride and the like are used. Each is preferably titanium tetrachloride, silica sol, or zirconium chloride.

Preferred materials among the above-mentioned titania oxide, zirconium oxide and silicon oxide are mixed at a predetermined weight ratio, and are mixed at 80 to 160 ° C., preferably 100 to 140 ° C., for 8 to 16 hours, preferably. Is 10-1
Dry for 4 hours. At a temperature higher than that, the drying speed becomes too fast, and a uniform composite oxide precursor cannot be obtained. The calcination is performed at 300 to 800 ° C., preferably 350 to 700 ° C., for 1 to 10 hours, preferably 2 to 6 hours in an oxidizing atmosphere. If the treatment time is too long and the firing temperature is too high, sintering occurs and the surface area decreases.

There are no particular restrictions on the raw material of V, W, or Mo, which is the B component serving as a support for the catalyst. V is vanadyl sulfate, ammonium vanadate, vanadyl oxalate, vanadyl chloride, and W is ammonium tungstate. Mo is molybdic acid, silicomolybdic acid, phosphomolybdic acid, such as tungstic acid, silicotungstic acid,
There are ammonium molybdate and the like, and a compound selected from each group is dissolved in a boric acid aqueous solution, an oxalic acid aqueous solution, a methylamine solution, or the like to form a supporting solution for each carrier. Of these materials, ammonium vanadate, ammonium tungstate and ammonium molybdate are preferred. These supporting solutions may be used as a mixture.

The carrier is impregnated with a solution containing V, W, and Mo selected from the raw materials of V, W, and Mo described above,
Dry at 0C, preferably 100-140C for 8-16 hours, preferably 10-14 hours. If the active component is weakly adsorbed on the carrier, the component is redistributed during drying, resulting in non-uniform distribution. In order to make the distribution of the active ingredient uniform, the temperature should be raised slowly in the above temperature range.

The calcination is performed at 300 to 800 ° C., preferably at 35 ° C.
1 to 10 hours at 0 to 700 ° C, preferably 2 to 6 hours,
Performed in an oxidizing atmosphere. If the treatment time is too long simultaneously with the calcination of the support and the reaction temperature is too high, the surface area decreases due to sintering, and the activity decreases. Thus, the first catalyst for decomposition treatment of an organic chlorine compound of the present invention is prepared.

In the second catalyst of the present invention, the crystallinity of the component B needs to be within a specific range, and for this purpose, the calcination must be performed at 300 to 800 ° C. If the firing is performed at a low temperature, the crystal growth is not sufficiently performed and the crystallinity is too low, and if the temperature is too high, the crystallinity is too high and a highly active catalyst cannot be obtained. It is preferable to use ammonium vanadate, ammonium tungstate, or ammonium molybdate as a raw material of the component B, and the other components in the catalyst can serve as nuclei (seed) to promote crystal growth.

The catalyst of the present invention may have a honeycomb shape depending on the application.
It can be formed into a pellet, and the performance as a catalyst can be exhibited by applying it to a cloth-like substrate such as glass fiber. The conditions for use may be such that the SV value is 20,000 / h or less, preferably 10,000 / h or less.
The heat treatment may be performed at 0 ° C. or lower, preferably 300 ° C. or lower.

[0024]

Next, the present invention will be described specifically with reference to examples. The measurement of the amount of crystalline oxide in the obtained catalyst by X-ray diffraction was performed as follows. The sample was packed in a glass cell having a depth of 0.2 mm, and wide-angle X-ray measurement was performed. The X-ray diffraction measuring device is Rigaku Denki RAD-rB. The slit configuration is DS (divergence slit) = 1.0
°, and RS (receiving slit) = 0.3mm, RS _M = (none), was used with monochromatic with curved graphite monochromator Cu-K [alpha line output of 50 kV / 200 mA. The measurement method is the symmetric reflection method, and the scan is 3 mm / mi.
n, step 0.01 °, 2θ range 3 to 90 ° were measured. The diffraction angles of the crystalline substances of V ₂ O ₅ , WO ₃ and MoO ₃ are 20.2, 23.5 and 27.3, respectively.
At that time, the peak intensity, the X-ray diffraction intensity and the mass absorption coefficient of the pure crystalline substance, and the average mass absorption coefficient of the sample were measured. The amount of metal in the catalyst was measured by ICP, and the crystallinity was calculated.

Example 1 A binary composite oxide carrier (TiO ₂ —SiO ₂ ) composed of titania oxide and silicon oxide was prepared by the following method. 60 g of distilled water was added to 3.75 g of a TiCl ₄ (containing about 16 wt% as Ti) solution, stirred and mixed while cooling with ice, and ammonia water (28 wt%) was pH = 7 to
The mixture was neutralized until it reached 8. The obtained solution was dispensed into a centrifuge tube and centrifuged at 3000 rpm for 1 minute. The supernatant was discarded, distilled water was added to the residue, and the mixture was stirred and mixed, and centrifuged again at 3000 rpm for 1 minute. After repeating this operation five times, 0.25 g of Snowtex O (silica sol manufactured by Nissan Chemical; containing about 20 wt% as SiO ₂ ) was added, mixed, and dried at 120 ° C. for 12 hours. Next, the mixture is fired at 500 ° C. for 2 hours in an air atmosphere, pulverized and sized so as to have an average particle size of 300 to 500 μm, and a binary composite oxide carrier composed of TiO ₂ —SiO ₂ (TiO ₂ : 95 wt%, SiO ₂ : 5 wt%).

Next, the above-mentioned binary composite oxide carrier was impregnated with an aqueous solution of oxalic acid in which ammonium vanadate was dissolved (prepared so that ₅ wt% V ₂ O ₅ was added to the carrier), and the carrier was mixed with 120 wt. Dried for 12 hours at 500C
Sintering for 2 hours in an air atmosphere at a temperature of V ₂ O ₅ / TiO ₂
Was obtained -SiO ₂ becomes the catalyst. V ₂ O ₅ in the obtained catalyst
Was 44%.

Example 2 V ₂ O ₅ and WO ₃ were respectively 5 relative to the binary composite oxide carrier comprising TiO ₂ —SiO ₂ prepared in Example 1.
impregnated with the solution prepared as carried wt%, or less in the same manner as in Example _{1, V 2 O 5 · WO 3} / TiO 2
Was prepared -SiO ₂ becomes the catalyst. V ₂ in the obtained catalyst
The crystallinity of O ₅ is 38% and the crystallinity of WO ₃ is 42%
Met.

Comparative Example 1 A catalyst was produced in the same manner as in Example 1, except that H-type mordenite-type zeolite (trade name “HSZ-640HOA”, Si / Al = 10, manufactured by Tosoh Corporation) was used as a carrier. .

Comparative Example 2 A catalyst V ₂ O ₅ / TiO ₂ was prepared in the same manner as in Example 1 except that the addition of the silica sol was omitted.
The crystallinity of V ₂ O ₅ in this catalyst was 61%.

Comparative Example 3 The addition of silica sol was omitted, and the firing temperature was raised from 500 ° C. to 9
A catalyst of V ₂ O ₅ / TiO ₂ was produced in the same manner as in Example 1 except that the temperature was changed to 00 ° C. The crystallinity of V ₂ O ₅ in this catalyst was 83%.

Comparative Example 4 A composite oxide carrier comprising 50 wt% of TiO _{2 and} 50 wt% of ZrO ₂ was prepared by the following method. T
3.75 iCl ₄ (containing about 16 wt% as Ti) solution
Then, 60 g of distilled water was added to the resulting mixture, and the mixture was stirred and mixed while cooling with ice. Aqueous ammonia (28 wt%) was added until pH = 7 to 8 for neutralization. Dispense the resulting solution into a centrifuge tube,
After centrifugation at 3000 rpm for 1 minute, the supernatant was discarded, distilled water was added to the residue, mixed, and centrifuged again at 3000 rpm for 1 minute. After repeating this operation five times, zirconia sol (zirconia sol manufactured by Nissan Chemical; containing about 30.4 wt% as ZrO ₂ ) is added.
29 g was added, mixed, and dried at 120 ° C. for 12 hours.
Next, the mixture is fired at 500 ° C. for 2 hours in an air atmosphere, pulverized and sized so as to have an average particle size of 300 to 500 μm.
A binary composite oxide carrier composed of iO ₂ -ZrO ₂ was obtained.
Next, Pd and Pt were added to the composite oxide carrier at 2w respectively.
The catalyst was prepared by carrying t%.

Reference Example 1 [Decomposition rate of monochlorobenzene] Air containing 120 ppm of monochlorobenzene (MCB: C ₆ H ₅ Cl) as a model compound of an organic chlorine compound and hydrogen chloride (HCl) as an acidic substance was treated as a gas to be treated. And the catalyst has a space velocity SV of 500 to 300 ° C. and a space velocity of 500.
It passed at 0 hr ^-1 . The catalyst used was obtained in Example 1 and Comparative Examples 1 to 3. The analysis of the processing gas was performed using a gas chromatograph [GC-8A (Shimadzu Corporation) (FI
D)], and the value calculated by the following equation was taken as the decomposition rate. Decomposition rate (%) = (1− (MCB concentration after reaction) / (MCB concentration before reaction)) × 100 The results are shown in FIG. As is clear from FIG. 1, the catalyst of the present invention was prepared using zeolite (Comparative Example 1) or V ₂ O ₅ / TiO _2.
It was shown that the activity was higher than that of the catalysts of Comparative Examples 2 and 3. It was also shown that if the crystallinity of V ₂ O _{5 in} the catalyst was too high, the activity as a catalyst would be low.

REFERENCE EXAMPLE 2 [Evaluation of catalyst life] Air containing monochlorobenzene and SOx was used as the gas to be treated, and the temperature was 10 ° C. at 200 ° C. and a space velocity SV value of 5000 hr ⁻¹ .
The treatment gas was analyzed continuously for 00 hours and analyzed at arbitrary time intervals, the decomposition rate of monochlorobenzene was calculated, and the degree of deterioration of the activity due to SOx catalyst poisoning was evaluated. The catalyst used was that obtained in Example 2, Comparative Examples 1, 2 and 4. The results are shown in FIG. As is clear from FIG.
It was shown that the catalyst of the present invention was not significantly affected by SO ₂ and maintained a stable activity.

Reference Example 3 [Decomposition rate of methylene chloride] Air containing 120 ppm of methylene chloride (CH ₂ Cl ₂ ) as a model compound of an aliphatic organic chlorine compound and hydrogen chloride (HCl) as an acidic substance was used as a gas to be treated. 200-300 ° C., space velocity SV value 5000h
It passed at r ^-1 . The catalyst used was that obtained in Example 2 and Comparative Example 4. The analysis of the processing gas was performed by a gas chromatograph [GC-8A (FID) manufactured by Shimadzu Corporation] to calculate the decomposition rate of methylene chloride. The results are shown in FIG. As is clear from FIG. 3, the catalyst of the present invention
It was also suggested that catalyst poisoning by acidic substances such as SOx and HCl was suppressed, and that aliphatic organic chlorine compounds such as methylene chloride could be efficiently decomposed and detoxified.

[0035]

According to the present invention, an organic chlorine compound contained in a low concentration together with an acidic substance, which is a main cause of deterioration of the catalyst in the exhaust gas from the incinerator, can be used stably with little deterioration of the catalyst and can be highly removed. At a low rate, low cost, that is, a small amount of catalyst is used, and it is possible to realize a low exhaust gas temperature.

[Brief description of the drawings]

FIG. 1 is a diagram showing the effect of reaction temperature on monochlorobenzene decomposition of a catalyst of the present invention.

FIG. 2 is a view showing the results of a life evaluation test of the catalyst of the present invention.

FIG. 3 is a graph showing the influence of reaction temperature on methylene chloride decomposition of the catalyst of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Riko Yabe 23 Uji Kozakura, Uji City, Kyoto Unitika Inside the Central Research Laboratory of Unitika Co., Ltd. (72) Inventor Takehiko Shimomura 23 Uji Kozakura Uji City, Kyoto Pref. Inside

Claims (3)

[Claims] 1. A composition comprising the following components A and B,
An organochlorine compound decomposition catalyst, wherein the component B is 1 to 40% by weight based on the component. (A): a composite oxide of two or more binary systems consisting of (a) titanium oxide and (b) zirconium oxide and / or silicon oxide, provided that (b) is 2 to 40 wt% with respect to (a). is there. (B): a composition comprising (a) a metal or metal oxide of vanadium, or (b) a composition comprising a metal or metal oxide of (b) tungsten and / or (c) a metal or metal oxide of molybdenum. However, (b) or (c) has a weight ratio of 10 or less to (a). 2. The catalyst according to claim 1, wherein the crystallinity of (B), (B) or (C) in the component (B) is 60% or less. . 3. After preparing and drying the raw material of the component A, 30
After baking in an air stream at 0 to 800 ° C. to prepare a composite oxide, impregnating this with a solution containing the B component, and drying,
The method for producing a catalyst according to claim 1 or 2, wherein the catalyst is calcined at 300 to 800 ° C in an air stream.