JP4348912B2 - Catalyst for decomposing chlorinated organic compound and method for decomposing chlorinated organic compound - Google Patents

Description

【００３４】
＜触媒Ｂの調製＞
上記の触媒Ａの調製において、前記の調製（２）で得たＳｉＯ_２−ＴｉＯ_２２元系複合酸化物粉末（１７％ＳｉＯ_２／８３％ＴｉＯ_２）を使用した以外は触媒（Ａ）の調製と同様にして次の表２に示す組成の触媒Ｂ：Ｖ_２Ｏ_５−ＭｏＯ_３／（１７％ＳｉＯ_２−ＴｉＯ_２）−ＴｉＯ_２を得た。
【００３５】
【表２】

【００３６】
＜評価方法＞
ガラス製反応器に上記の各触媒を３０ｍｌ充填し、常圧固定床流通反応装置で活性試験を行った。触媒固定床の寸法は縦２８ｍｍ、横２８ｍｍ、高さ３８ｍｍであった。原料ガス組成はオルトクロルフェノール（ＯＣＰ）：１００ｐｐｍ、Ｏ_２：１０ｖｏｌ％、Ｈ_２Ｏ：１０ｖｏｌ％、Ｎ_２：バランス量の組成であった。原料ガスのＳＶは５０００ｈ^−１であった。１６０℃と１８０℃の各温度で５時間保持した後、反応装置通過ガスをマイクロシリンジでサンプリングし、ガスクロマトグラフィーで分析した。分析は絶対検量線法で行った。表３に結果を示す。
【００３７】
【表３】

【００３８】
【発明の効果】
以上説明した本発明によれば、低温度でダイオキシン等の塩素化有機化合物を高効率で分解することが出来る触媒および当該触媒を使用した塩素化有機化合物の分解方法が提供され、本発明の工業的価値は顕著である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst for decomposing chlorinated organic compounds and a method for decomposing chlorinated organic compounds, and more specifically, a chlorinated organic compound capable of decomposing chlorinated organic compounds such as dioxin with high efficiency at a low temperature. The present invention relates to a decomposition catalyst and a decomposition method of a chlorinated organic compound.
[0002]
[Prior art]
Combustion exhaust gas discharged from incinerators that treat municipal waste and industrial waste contains various harmful components, but chlorinated organic compounds such as highly toxic dioxins and their precursors, aromatic chlorine compounds. Removal of nitrogen oxides, which are causative agents of compounds and photochemical smog, is particularly important.
[0003]
Various methods are known as a method for removing chlorinated organic compounds from combustion exhaust gas. In particular, catalytic cracking is an excellent method for decomposing chlorinated organic compounds under conditions of 500 ° C. or less. By the way, the catalytic decomposition of a chlorinated organic compound is required to be performed at a temperature of 250 ° C. or lower because dioxins once decomposed are regenerated at a decomposition temperature of 300 ° C. or higher.
[0004]
Furthermore, in recent years, in city garbage incineration facilities, power is generated by steam obtained for the purpose of recovering heat generated at the time of garbage incineration, and electric power is supplied to the city garbage incineration facility and surplus power is sold. By the way, when the above steam is used to maintain the reaction temperature of the catalyst layer for chlorinated organic compound decomposition, there is a disadvantage that a larger amount of steam is consumed as the reaction temperature is higher. Therefore, from such a viewpoint, operation at a reaction temperature as low as possible, specifically, a reaction temperature of 200 ° C. or less is required.
[0005]
On the other hand, catalytic decomposition of chlorinated organic compounds is considered an oxidation reaction, and the reaction rate inevitably decreases as the reaction temperature decreases. Therefore, when an attempt is made to obtain a predetermined decomposition rate by performing catalytic cracking at a lower temperature, it is necessary to increase the amount of catalyst or decrease the amount of processing gas per unit time. However, in the municipal waste incineration facility, since it is difficult to reduce the amount of processing gas, there is a problem that the processing apparatus becomes enormous.
[0006]
On the other hand, TiO ₂ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ or the like can be generally used as the catalyst carrier, but in the case of a chlorinated organic compound decomposition catalyst, SO 2 is contained in the combustion exhaust gas. since in many cases are, TiO ₂ having a resistance to sO ₂ is generally used. For example, in Japanese Patent No. 2633316, a catalyst in which an active component V ₂ O ₅ and WO ₃ are supported on a TiO ₂ carrier is used. In Japanese Patent No. 2916259, a binary of Ti, Si, Zr or By using a ternary composite oxide, the dispersibility of the active ingredient is improved to improve the catalyst performance.
[0007]
In Japanese Patent No. 2633316, a reaction temperature of 270 to 290 ° C. is adopted. However, such a temperature is not sufficiently low, and in Japanese Patent No. 2916259, the temperature is 200 ° C. The reaction conditions of SV of 2000 hr ⁻¹ are employed, and a large amount of catalyst needs to be used.
[0008]
As described above, none of the conventional catalysts for decomposing chlorinated organic compounds is sufficiently satisfactory for use in a low-temperature condition and a compact processing apparatus.
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and its purpose is to decompose a chlorinated organic compound such as dioxin with high efficiency at a low temperature and to decompose the chlorinated organic compound using the catalyst. It is to provide a method.
[0010]
[Means for Solving the Problems]
As a result of various studies, the present inventors have obtained the following various findings. That is, the chlorinated organic compound resolving power of the catalyst using the SiO ₂ —TiO ₂ binary composite oxide as a carrier can be enhanced by adjusting the acid amount of the binary composite oxide to a specific range or less.
[0011]
The present invention has been achieved on the basis of the above findings. The first gist of the present invention is a catalyst for decomposing chlorinated organic compounds in which an active component is supported on a carrier, and TiO _{2 is used} as the carrier. A mixture of SiO ₂ —TiO ₂ binary composite oxide and TiO ₂ having a structure in which SiO ₂ particles are adhered on the particle surface and having an acid amount of 0.23 mmol / g or less determined by the NH ₃ adsorption method ( However it consists in chlorinated organic compounds cracking catalyst, characterized by comprising using a mixture of TiO ₂ is 30 to 90 wt%) with respect to the mixture.
[0012]
The second gist of the present invention is a method for decomposing a chlorinated organic compound, characterized in that the chlorinated organic compound decomposition catalyst and the chlorinated organic compound-containing gas are brought into contact at a temperature of 100 to 250 ° C. Exist.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
First, the chlorinated organic compound decomposition catalyst of the present invention (hereinafter simply referred to as “catalyst”) will be described. The catalyst of the present invention comprises an active component supported on a SiO ₂ —TiO ₂ binary composite oxide support.
[0014]
The titanium source of the SiO ₂ —TiO ₂ binary composite oxide can be selected from titanium chloride, titanyl sulfate, metatitanic acid, and the like. The silicon source can be selected from colloidal silica and water glass.
[0015]
The active component is usually at least one selected from the group consisting of V, Cr, Mo, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, W, In, and Ir. A metal and / or its oxide. Among these, vanadium (V) oxide is preferably used because it is inexpensive and has a high decomposition rate of chlorinated organic compounds. The ratio of the active ingredient to the carrier is usually in the range of 1 to 10% by weight.
[0016]
The shape and size of the catalyst are appropriately selected depending on the presence or absence of dust in the chlorinated organic compound-containing gas, the amount of treatment gas, the size of the reactor, and the like. Examples of the shape of the catalyst include a honeycomb shape, a columnar shape, a spherical shape, and a plate shape.
[0017]
As a method for producing a honeycomb-shaped catalyst in which an active component is supported on a carrier, (a) the carrier component and the active component or its raw material are kneaded together with a molding aid, and then shaped into a honeycomb shape by an extrusion molding method or the like. And (b) a method of impregnating and supporting a carrier component and an active component on a honeycomb-shaped substrate.
[0018]
In the present invention, a SiO ₂ —TiO ₂ binary composite oxide having an acid amount of 0.23 mmol / g or less determined by the NH ₃ adsorption method is used as the carrier.
[0019]
The method for obtaining the acid amount by the NH ₃ adsorption method is as follows. That is, a TPD-MASS device (AGS-7000 type) manufactured by Anerva Co., Ltd. is used as a measuring device. First, a He flow treatment (400 ° C. × 30 minutes) is performed as a pretreatment for 100 mg of the sample. Next, as NH ₃ adsorption / exhaust treatment, an adsorption treatment is performed at 700 Torr for 15 minutes, followed by vacuum exhaust treatment (100 ° C. × 30 minutes) and He flow treatment (100 ° C. × 30 minutes). Then, perform the Atsushi Nobori of NH ₃ at between 700 ° C. from room temperature, the amount of released NH ₃ to (mmol / g) was measured, which is referred to as acid content.
[0020]
As an example of the production method according to the above (a) of the catalyst comprising the active component supported on the low acid amount SiO ₂ —TiO ₂ binary composite oxide carrier as described above, the following method is exemplified. .
[0021]
(1) Dissolve ammonium metavanadate in an aqueous solution of about 10% by weight monoethanolamine.
(2) A titanium sulfate solution is hydrolyzed to obtain a metatitanic acid slurry.
(3) After adjusting the pH by adding 15 wt% ammonia water to the metatitanic acid slurry, reflux treatment is performed for 1 hour or more.
(4) The obtained slurry is filtered, and the obtained cake is dried at a temperature of 50 to 150 ° C. for 3 to 50 hours, then baked at a temperature of 400 to 650 ° C., and pulverized after cooling.
(5) Add silica sol, and perform sufficient stirring for 1 hour or more.
(6) The obtained slurry is filtered, and the obtained cake is dried at a temperature of 50 to 150 ° C for 3 to 50 hours, then baked at a temperature of 400 to 650 ° C, and pulverized after cooling.
(7) The powdery SiO ₂ —TiO ₂ binary mixed oxide obtained is mixed with a predetermined amount of TiO ₂ to form a carrier.
(8) The carrier and the aqueous solution prepared in (1) are kneaded with a kneader.
(9) (i) Further, the kneaded product kneaded with the addition of a molding aid is extruded and dried at a temperature of 50 to 150 ° C. for 3 to 50 hours, and then in an air stream of SV100 to 2000 Hr ⁻¹ , 400 to 400 Firing is performed at a temperature of 650 ° C., or (ii) the kneaded product is dried at a temperature of 50 to 150 ° C. for 3 to 50 hours, and calcined at a temperature of 400 to 650 ° C., and then molded by adding a molding aid.
[0022]
Moreover, the following method is illustrated as an example of the above-mentioned manufacturing method (b). That is, a carrier component prepared in the above (2) to (7) is coated on a base material having a desired shape such as a columnar shape, a spherical shape, a honeycomb shape, a plate shape, and the aqueous solution prepared in the above (1). It is applied and impregnated with the active ingredient, dried at 50 to 150 ° C. for 3 to 50 hours, and then fired at a temperature of 450 to 650 ° C.
[0023]
In any of the above methods, the operation of (4) is performed between the above (3) and (5), that is, the operation of (4) (formation of titanium oxide by firing) is omitted, and (3) When silica gel is added to the metatitanic acid slurry obtained in (1), it is converted into a composite oxide at the atomic level, so that the acid amount of the SiO ₂ —TiO ₂ binary composite oxide becomes high. The same applies when a highly reactive alkoxysilane is used instead of silica gel.
[0024]
In short, in the present invention, it is important that SiO ₂ and TiO ₂ are complex oxides at the particle level, and SiO ₂ —TiO ₂ binary complex oxide has SiO ₂ particles on the surface of TiO ₂ particles. Has an attached structure. In the SiO ₂ —TiO ₂ binary composite oxide, the SiO ₂ content is usually 1 to 20% by weight, preferably 2 to 15% by weight.
[0025]
In the case of the operation (7), the mixing amount of TiO ₂ with respect to the mixture of SiO ₂ —TiO ₂ binary composite oxide and TiO ₂ is 30 to 90% by weight, preferably 50 to 90% by weight. By such a mixing operation, the moldability can be improved while maintaining the effect of the SiO ₂ —TiO ₂ binary composite oxide.
[0026]
Next, a method for using the catalyst of the present invention (a method for decomposing chlorinated organic compounds) will be described. In the present invention, the catalyst and the chlorinated organic compound-containing gas are brought into contact with each other. Examples of the chlorinated organic compound-containing gas include dioxins represented by 2,3,7,8-tetrachlorodibenzodioxin and 2,3,4,7,8-pentachlorodibenzofuran, 3,3 ′, Coplanar PCBs represented by 4,4 ′, 5-pentachlorobiphenyl are contained in an amount of about 0.1 to 200 ng / m ³ (NTP) (equivalent toxic equivalent value), and a dioxin precursor. Combustion of substances containing chlorobenzenes such as monochlorobenzene and trichlorobenzene, chlorophenols such as O-chlorophenol and trichlorophenol, and chlorobenzofuran, specifically municipal waste and industrial waste The exhaust gas etc. at the time of carrying out are mentioned. Such a chlorinated organic compound-containing gas contains oxygen together with moisture, and the content thereof is usually 0.5 to 25 vol%, preferably 1 to 21 vol%.
[0027]
The chlorinated organic compound-containing gas as described above is usually introduced into the contact process after removing dust and heavy metals through a bag filter. If necessary, the acid gas may be removed by treatment with a slaked lime reaction tower before treatment with the bag filter.
[0028]
Contact temperature of chlorinated organic compound containing gas and catalyst, 1 00-250 ° C., preferably from 100 to 200 ° C.. When the contact temperature exceeds 250 ° C., the decomposition rate of the chlorinated organic compound increases, but it is disadvantageous from the viewpoint of saving steam for heating the catalyst layer as well as the problem that the decomposed dioxins are re-synthesized. When the contact temperature is less than 100 ° C., condensation causing trouble in operation is caused. The pressure of the catalyst layer is usually −0.05 to 0.9 MPa, preferably −0.01 to 0.5 MPa as a gauge pressure. Moreover, space velocity (SV) is 100-50000Hr < ^-1 > normally, Preferably it is 1000-20000Hr- ¹ .
[0029]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded. In the following, “%” means “% by weight” unless otherwise specified.
[0030]
<Preparation of _SiO 2 -TiO ₂ 2-way complex oxide (1)>
A metatitanic acid slurry (TiO ₂ concentration 30 wt%, manufactured by Ishihara Sangyo Co., Ltd.) was added to 2667 g of 15 wt% ammonia water 977 g to prepare a pH of 9.5 to 10, and then maintained at 60 ° C. for 5 hours while maintaining the pH. The mixture was aged by heating with sufficient stirring. Thereafter, the slurry was taken out by cooling, dehydrated by filtration, and the obtained cake was dried at 110 ° C. for 20 hours, then heated to 550 ° C. at a rate of 50 ° C./Hr, and kept at the same temperature for 5 hours. And after cooling, it grind | pulverized to the appropriate particle size and obtained Ti oxide. To this Ti oxide, 211 g of silica sol (“Cataloid S-20L” manufactured by Catalyst Kasei Co., Ltd.) was added, and after sufficient stirring at room temperature for 2 hours, the slurry was taken out and filtered and dehydrated. After drying for 20 hours, the temperature was raised to 550 ° C. at a rate of 50 ° C./Hr and kept at the same temperature for 5 hours. After cooling, crushed to a suitable particle _size, SiO 2 / TiO ₂ ratio to obtain a 5 wt% / 95 wt% of _SiO 2 -TiO ₂ 2-element complex oxide.
[0031]
<Preparation of _SiO 2 -TiO ₂ 2-way complex oxide (2)>
After adding 854 g of 15 wt% ammonia water to 2330 g of metatitanic acid slurry (TiO ₂ concentration 30 wt%, manufactured by Ishihara Sangyo Co., Ltd.) to adjust the pH to 9.5-10, the pH is maintained at 60 ° C. for 5 hours while maintaining the pH. The mixture was aged by heating with sufficient stirring. Subsequently, 717 g of silica sol (“Cataloid S-20L” manufactured by Catalyst Kasei Co., Ltd.) was added, and further heat aging under the same conditions as described above was performed for 1 hour. Thereafter, the slurry was cooled, taken out, filtered and dehydrated, and the resulting cake After drying at 100 ° C. for 20 hours, the temperature was raised to 600 ° C. at a rate of 75 ° C./Hr and held at the same temperature for 5 hours, and after cooling, pulverized to an appropriate particle size, and the SiO ₂ / TiO ₂ ratio Of 17 wt% / 83 wt% of SiO ₂ —TiO ₂ binary composite oxide was obtained.
[0032]
<Preparation of catalyst A>
A starting material liquid (1) was prepared by dissolving 1029 g of ammonium metavanadate and 736 g of ammonium paramolybdate in 6000 g of a 10% aqueous monoethanolamine solution heated to 80 ° C. 1900 g of SiO ₂ —TiO ₂ binary complex oxide powder (5% SiO ₂ /95% TiO ₂ ) obtained in the above preparation (1) and 5700 g of pure TiO ₂ powder in one-arm kneader in 1 hour The mixture was dry-mixed, the raw material liquid (1) and 1000 g of forming aid were added to the mixture and kneaded for another 2 hours, and the resulting mixture was formed into a honeycomb structure having a diameter of 5 mm from an extruder. The obtained molded product was dried at a temperature of 130 ° C. for 24 hours, then calcined for 3 hours under conditions of SV100 h ⁻¹ and a temperature of 500 ° C., and the catalyst (A) having the composition shown in Table 1 below: V ₂ O _5- MoO ₃ / (SiO ₂ —TiO ₂ ) —TiO ₂ was obtained.
[0033]
[Table 1]

[0034]
<Preparation of catalyst B>
In the preparation of the catalyst A, the catalyst (A) was prepared except that the SiO ₂ —TiO ₂ binary composite oxide powder (17% SiO ₂ /83% TiO ₂ ) obtained in the preparation ( ₂ ) was used. In the same manner as in the preparation, catalyst B having the composition shown in the following Table 2 was obtained: V ₂ O ₅ —MoO ₃ / (17% SiO ₂ —TiO ₂ ) —TiO ₂ .
[0035]
[Table 2]

[0036]
<Evaluation method>
A glass reactor was filled with 30 ml of each of the above catalysts, and the activity test was performed in an atmospheric pressure fixed bed flow reactor. The dimensions of the catalyst fixed bed were 28 mm in length, 28 mm in width, and 38 mm in height. The raw material gas composition was orthochlorophenol (OCP): 100 ppm, O ₂ : 10 vol%, H ₂ O: 10 vol%, and N ₂ : balance amount. The SV of the source gas was 5000h- ¹ . After holding at 160 ° C. and 180 ° C. for 5 hours, the gas passing through the reactor was sampled with a microsyringe and analyzed by gas chromatography. The analysis was performed by the absolute calibration curve method. Table 3 shows the results.
[0037]
[Table 3]

[0038]
【The invention's effect】
According to the present invention described above, a catalyst capable of efficiently decomposing chlorinated organic compounds such as dioxins at a low temperature and a method for decomposing chlorinated organic compounds using the catalyst are provided. The target value is remarkable.

Claims (3)

A catalyst for decomposing chlorinated organic compounds in which an active component is supported on a carrier, wherein the carrier has a structure in which SiO ₂ particles are adhered on the surface of TiO ₂ particles, and an acid determined by an NH ₃ adsorption method. A mixture of SiO ₂ —TiO ₂ binary composite oxide and TiO ₂ having an amount of 0.23 mmol / g or less (provided that the mixed amount of TiO ₂ with respect to the mixture is 30 to 90% by weight). A catalyst for decomposing chlorinated organic compounds. The catalytically active component is at least one metal selected from the group consisting of V, Cr, Mo, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, W, In and Ir and / or its oxidation The catalyst for decomposing chlorinated organic compounds according to claim 1, which is a product. A method for decomposing a chlorinated organic compound , comprising contacting the chlorinated organic compound decomposition catalyst according to claim 1 or 2 and a chlorinated organic compound-containing gas at a temperature of 100 to 250 ° C.