JP3734645B2 - Catalyst for decomposing chlorinated organic compound and method for decomposing chlorinated organic compound - Google Patents

Description

【００６０】
結果を表１〜表６に示す。なお、表１、表２および表３は、実施例１に係る触媒を用いた場合の結果であり、それぞれ反応管５を１４０℃、１７０℃および２００℃で加熱処理した場合の結果を示している。一方、表４、表５および表６は、実施例２に係る触媒を用いた場合の結果であり、それぞれ反応管５を１４０℃、１７０℃および２００℃で加熱処理した場合の結果を示している。各表中において、ダイオキシン類を示す各略号は下記の化合物を示している。また、“ＴＥＦ”は毒性等価係数を、“ＴＥＱ”は利用したダイオキシン類標準品の毒性等量を示している。
ＰＣＤＤｓ：ポリ塩化ジベンゾ・パラ・ダイオキシン類
Ｔ₄ＣＤＤ：四塩化ジベンゾダイオキシン
Ｐ₅ＣＤＤ：五塩化ジベンゾダイオキシン
Ｈ₆ＣＤＤ：六塩化ジベンゾダイオキシン
Ｈ₇ＣＤＤ：七塩化ジベンゾダイオキシン
Ｏ₈ＣＤＤ：八塩化ジベンゾダイオキシン
ＰＣＤＦｓ：ポリ塩化ジベンゾフラン類
Ｔ₄ＣＤＦ：四塩化ジベンゾフラン
Ｐ₅ＣＤＦ：五塩化ジベンゾフラン
Ｈ₆ＣＤＦ：六塩化ジベンゾフラン
Ｈ₇ＣＤＦ：七塩化ジベンゾフラン
Ｏ₈ＣＤＦ：八塩化ジベンゾフラン
【００６１】
【表１】

【００６２】
【表２】

【００６３】
【表３】

【００６４】
【表４】

【００６５】
【表５】

【００６６】
【表６】

【００６７】
【発明の効果】
本発明の塩素化有機化合物分解用触媒は、上述のような酸化物担体上に金の微粒子を担持させたものであるため、排気ガス中に含まれる塩素化有機化合物に対する高い分解活性を発揮し得る。
【００６８】
また、本発明に係る塩素化有機化合物の分解方法は、本発明の塩素化有機化合物分解用触媒を用いているため、排気ガス中に含まれる塩素化有機化合物を効果的に分解することができる。
【図面の簡単な説明】
【図１】実施例の評価において用いた触媒活性試験装置の概略図。[0001]
[Technical field to which the invention belongs]
The present invention relates to a catalyst and a method for decomposing a compound, and more particularly to a catalyst for decomposing a chlorinated organic compound and a method for decomposing a chlorinated organic compound.
[0002]
[Prior art and its problems]
Dioxins, polychlorinated biphenyls (PCB), chlorophenol, chlorobenzene are present in exhaust gas generated from incineration facilities for treating industrial waste and general household waste, coal power generation facilities, steelmaking facilities, metal refining facilities, etc. Contains chlorinated organic compounds such as
[0003]
Here, dioxins are a general term for polychlorinated dibenzo-para-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). As is well known, dioxins are extremely toxic environmental pollutants. Dioxin (T_FourCDDs) are particularly known as the strongest toxic substances. On the other hand, chlorinated organic compounds such as polychlorinated biphenyls, chlorophenols, and chlorobenzenes are less toxic than dioxins, but are exhausted under certain conditions, for example, using various elements in fly ash as catalysts in an incinerator. Since it has been found that it is easily converted into dioxins within the temperature range of the gas, it is recognized as an environmental pollutant like dioxins. For this reason, from the viewpoint of environmental conservation, the necessity to remove various chlorinated organic compounds as described above from the exhaust gas is increasing rapidly.
[0004]
By the way, mainly two methods have been proposed as a method for removing chlorinated organic compounds from exhaust gas. One is a technique for adsorbing a chlorinated organic compound on an adsorbent such as activated carbon, and the other is a technique for decomposing the chlorinated organic compound using a catalyst. However, the method using an adsorbent increases the implementation cost because it cannot effectively absorb and remove a small amount of chlorinated organic compound contained in the exhaust gas unless a large amount of adsorbent is used. There is doubt about practicality unless the disposal method and the recycling method of the used adsorbent are established.
[0005]
For this reason, a technique for decomposing a chlorinated organic compound using a catalyst has attracted attention, and many catalysts have been proposed. For example, a denitration catalyst composed of vanadium pentoxide, tungsten oxide, and titania, a catalyst in which platinum is supported on the denitration catalyst (see JP-A-2-35914), silica-boria-alumina composite oxide, and moles of silica relative to alumina. Catalyst in which 0.1 to 10 g of at least one element selected from the group consisting of platinum, palladium and iridium or its oxide is supported per liter of at least one of zeolites having a ratio of 30 or more (See JP-A-7-163877), a mixed oxide catalyst containing vanadium oxide and an oxide of at least one element selected from the group consisting of yttrium, boron and lead (JP-A-9-29066) And the like) are known.
[0006]
  However, these catalysts areContained in exhaust gasAlthough it can decompose chlorinated organic compounds to some extent, its ability is small,Contained in exhaust gasIt is often difficult to say that the catalyst is truly effective for chlorinated organic compounds.
[0007]
  The purpose of the present invention is toContained in exhaust gasIt is to realize a catalyst having high decomposition activity for chlorinated organic compounds.
[0008]
[Means for Solving the Problems]
  The catalyst for decomposing chlorinated organic compounds of the present invention comprises:A catalyst for decomposing chlorinated organic compounds contained in exhaust gas,An oxide of at least one metal element selected from the group consisting of magnesium, aluminum, silicon, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten; An oxide carrier comprising at least one oxide of a rare earth element and supported on the oxide carrierThe average particle size is 30 nm or lessContains gold fine particles.
[0009]
  Here, the rare earth element is at least one selected from the group consisting of yttrium, lanthanum and cerium, for example.In this catalyst,For example, the atomic ratio of the rare earth element to the above metal element constituting the oxide support is 0.005 to 50, and the gold accounts for the total of the above metal element and rare earth element and gold constituting the oxide support. The atomic ratio is 0.0005 to 0.2.
  A catalyst for decomposing chlorinated organic compounds according to another aspect of the present invention is a catalyst for decomposing chlorinated organic compounds contained in exhaust gas, and includes magnesium, aluminum, silicon, titanium, vanadium, manganese, Oxidation comprising a complex oxide of at least one metal element selected from the group consisting of iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten and at least one rare earth element And a gold fine particle having an average particle size of 30 nm or less supported on the oxide carrier.
[0010]
  Of the present inventionfurtherOther aspects of chlorinated organic compound decomposition catalysts include:A catalyst for decomposing chlorinated organic compounds contained in exhaust gas,Hydroxide of at least one metal element selected from the group consisting of magnesium, aluminum, silicon, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten , A step of obtaining a coprecipitate containing at least one rare earth element hydroxide and a gold hydroxide in water, removing the coprecipitate from the water, and a metal element hydroxide or rare earth element contained in the coprecipitate The metal hydroxide and the gold hydroxide are obtained through a manufacturing process including a step of converting a metal element oxide, a rare earth element oxide and gold, respectively.
[0011]
  Of the present inventionfurtherOther aspects of chlorinated organic compound decomposition catalysts include:A catalyst for decomposing chlorinated organic compounds contained in exhaust gas,Hydroxide of at least one metal element selected from the group consisting of magnesium, aluminum, silicon, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten And a step of obtaining a coprecipitate comprising at least one kind of rare earth element hydroxide in the first water, removing the coprecipitate from the first water, and hydroxylating a metal element contained in the coprecipitate A metal oxide and a rare earth element hydroxide are converted into a metal element oxide and a rare earth element oxide to obtain an oxide carrier, and gold hydroxide is precipitated in the second water containing the oxide carrier. Obtained through a manufacturing process including a step and a step of removing the gold hydroxide together with the oxide carrier from the second water and converting the gold hydroxide into gold. It is.
[0012]
  The method for decomposing a chlorinated organic compound according to the present invention comprises:A method for decomposing chlorinated organic compounds contained in exhaust gas,In a high temperature atmosphere containing the above-described catalyst for decomposing chlorinated organic compounds according to the present inventionExhaust gasThe process to process is included. Here, the high temperature atmosphere is usually set to at least 140 ° C.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The catalyst for decomposing chlorinated organic compounds of the present invention includes an oxide carrier and gold fine particles supported on the oxide carrier, and is usually formed in a powdery or air-permeable porous shape. .
[0014]
The oxide carrier used here is at least selected from the group consisting of magnesium, aluminum, silicon, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten. It contains one type of metal element oxide and at least one type of rare earth element oxide.
[0015]
Here, as the oxide of the metal element, magnesium oxide (MgO), aluminum oxide (Al₂O_Three), Silicon oxide (SiO, SiO₂), Titanium oxide (TiO, Ti₂O_ThreeTiO₂), Vanadium oxide (VO, V₂O_Five), Manganese oxide (MnO, Mn_ThreeO_Four, Mn₂O_Three, MnO₂, MnO_Three, Mn₂O₇), Iron oxide (FeO, Fe_ThreeO_Four, Fe₂O_Three), Cobalt oxide (CoO, Co₂O_Three, Co_ThreeO_FourCoO₂), Nickel oxide (NiO, Ni_ThreeO_FourNiO₂), Copper oxide (CuO)₂, CuO), zinc oxide (ZnO), zirconium oxide (ZrO)₂), Niobium oxide (NbO, Nb)₂O_Three, NbO₂, Nb₂O_Five), Molybdenum oxide (MoO, MoO)₂, Mo₂O_Five, MoO_Three), Indium oxide (In₂O_Three), Tin oxide (SnO, SnO₂), Tungsten oxide (WO2, WO3, others having an intermediate oxidation number between 4 and 6). Among these metal oxides, preferred are MgO, Al since the dispersibility of the gold fine particles can be increased and the low-temperature oxidative decomposition activity of the catalyst of the present invention can be enhanced.₂O_Three, SiO₂TiO₂, MnO, Fe₂O_Three, Co_ThreeO_Four, NiO, CuO, ZnO, ZrO₂, Nb₂O_Five, MoO_Three, In₂O_ThreeAnd SnO₂1 type or 2 types or more selected from the group consisting of
[0016]
On the other hand, the rare earth element is not particularly limited, but usually, since it can realize more effective decomposition activity on the chlorinated organic compound, it is at least one selected from the group consisting of yttrium, lanthanum and cerium. Those are preferred. Examples of such rare earth element oxides include yttrium oxide (Y₂O_Three), Lanthanum oxide (La₂O_Three), Cerium oxide (CeO)₂, Ce₂O_Three).
[0017]
The metal element oxide and the rare earth element oxide contained in the oxide carrier may be a composite oxide of the metal element and the rare earth element. Here, as the complex oxide, for example, LaCoO_ThreeLaMnO_ThreeCan be mentioned. In this case, the oxide carrier may contain both or one of the above-described metal element oxide and the above-mentioned rare earth element oxide together with the composite oxide.
[0018]
The gold fine particles supported on the oxide carrier as described above are composed of gold alone, and are usually supported in a state of being dispersed on the oxide carrier in the form of fine particles having an average particle size of 30 nm or less. It is preferable.
[0019]
In the catalyst for decomposing chlorinated organic compounds of the present invention, the ratio of the oxide of the above-mentioned metal element constituting the oxide support to the oxide of the above-mentioned rare earth element is usually the above-described metal element constituting the oxide support. The above-mentioned rare earth element atomic ratio (rare earth element / metal element) is preferably set to 0.005 to 50, and more preferably 0.025 to 2.0. When this atomic ratio is less than 0.005, the decomposition activity with respect to the chlorinated organic compound decreases, and the catalyst of the present invention may not easily exhibit the required catalytic activity. Conversely, when the atomic ratio exceeds 50, the activity of the catalyst may be lower than when no rare earth element oxide is used.
[0020]
In addition, the amount of fine gold particles contained in the catalyst for decomposing chlorinated organic compounds of the present invention is usually such that the metal elements and rare earth elements constituting the above-mentioned oxide support and the gold contained in the catalyst for decomposing chlorinated organic compounds. The proportion of gold atoms in the total amount is preferably set to be 0.0005 to 0.2, and more preferably 0.005 to 0.1. When the ratio of gold is less than 0.0005, the decomposition activity on the chlorinated organic compound is lowered, and the catalyst of the present invention may not easily exhibit a required catalytic function. On the other hand, when the ratio exceeds 0.2, it becomes difficult to increase the decomposition activity of the chlorinated organic compound in proportion thereto, which is uneconomical. Further, the size of the gold fine particles is increased, and the decomposition activity of the chlorinated organic compound by the catalyst of the present invention may be decreased.
[0021]
The above-mentioned atomic ratio and gold ratio are the raw materials used in the catalyst production method of the present invention described later, that is, the amounts of precursors that can be converted into metal hydroxide, rare earth element hydroxide, and gold hydroxide, respectively. It is a value converted from.
[0022]
The catalyst for decomposing chlorinated organic compounds of the present invention is produced by the following production method. Hereinafter, a case of producing a catalyst for decomposing chlorinated organic compounds in which gold fine particles are supported on an oxide carrier containing iron oxide and lanthanum oxide (hereinafter referred to as “specific example” in the description of the production method). In this case, two types of methods for producing the catalyst for decomposing chlorinated organic compounds of the present invention will be described.
[0023]
(Method 1)
Process 1
In this step, first, a hydroxide of at least one metal element of the above metal elements (hereinafter referred to as a metal hydroxide), a hydroxide of at least one rare earth element of the above rare earth elements. A coprecipitate containing (hereinafter referred to as rare earth element hydroxide) and gold hydroxide is prepared in water.
When preparing such a coprecipitate in water, first, a precursor that can be converted into a metal hydroxide, a rare earth element hydroxide, and a gold hydroxide, that is, a metal hydroxide precursor, a rare earth element water, respectively. A predetermined amount of the oxide precursor and the gold hydroxide precursor is dissolved in water (preferably distilled water).
[0024]
The precursor used here is not particularly limited as long as the target hydroxide can be formed when the pH of the aqueous solution containing the precursor is adjusted to the alkaline side. Nitrate of the above-mentioned metal element as the precursor of the product, the nitrate of the above-mentioned rare earth element as the precursor of the rare earth element hydroxide, and chloroauric acid (HAuCl) as the precursor of the gold hydroxide_Four) Can be used respectively. Incidentally, in the case of a specific example, iron nitrate (Fe (NO_Three)_Three・ 9H₂O), lanthanum nitrate (La (NO_Three)_Three・ 6H₂O) and chloroauric acid (HAuCl)_Four・ 4H₂O) can be used. The total concentration of these precursors in the aqueous solution is usually preferably set to 1% or less.
[0025]
Next, the pH of the aqueous solution thus obtained is adjusted to the alkaline side, and a metal hydroxide, a rare earth element hydroxide and a gold hydroxide are simultaneously precipitated in water. Here, while stirring the aqueous solution usually at 100 rpm or more, an alkaline aqueous solution, for example, a sodium carbonate aqueous solution or a sodium hydroxide aqueous solution of about 5% by weight is gradually and gradually dropped into the aqueous solution. Incidentally, in the case of the specific example, it is preferable to set the pH of the aqueous solution to 9.0 ± 0.2 over about 1 hour by such work.
[0026]
Process 2
In this step, the metal hydroxide, rare earth element hydroxide and gold hydroxide obtained in step 1 are converted into metal oxide, rare earth element oxide and gold, respectively. Here, first, the aqueous solution in step 1 is filtered, and the coprecipitate formed in the aqueous solution is taken out. The coprecipitate is washed with ion exchange water or distilled water and then dried. Here, the washing is performed when Na carbonate aqueous solution or sodium hydroxide aqueous solution is used in Step 1, and Na⁺It is preferable to carry out until the ion concentration becomes 5 ppm or less. Moreover, it is preferable to perform drying until the coprecipitate after washing | cleaning is processed in the temperature range of 120-150 degreeC, and the water content of a coprecipitate becomes 10 weight% or less.
[0027]
Next, the coprecipitate washed and dried as described above is activated. Here, the coprecipitate is gradually heated in an oxidizing atmosphere, for example, in air, and heat-treated at a constant temperature for several hours. Incidentally, in the specific example, the space velocity is 100 hr.^-1The coprecipitate is placed in an air atmosphere set to, and the temperature of the air atmosphere is heated to 450 ° C. at a temperature increase rate of 10 ° C./min. And a coprecipitate is continuously heat-processed at 450 degreeC for 4 hours.
[0028]
By such activation treatment, the metal hydroxide, rare earth element hydroxide and gold hydroxide contained in the coprecipitate are converted into metal oxide, rare earth element oxide and gold, respectively (in the specific example, iron Hydroxide, lanthanum hydroxide and gold hydroxide are iron oxide (Fe₂O_Three), Lanthanum oxide (La₂O_Three) And gold (Au)), the desired catalyst for decomposing chlorinated organic compounds is usually obtained in powder form.
[0029]
In addition, in this method, when manufacturing the catalyst for chlorinated organic compound decomposition | disassembly whose oxide support | carrier is a complex oxide of a metal element and rare earth elements, the heating temperature at the time of activation processing is set higher.
[0030]
(Method 2)
Process 1
In this step, first, a coprecipitate containing a metal hydroxide and a rare earth element hydroxide is prepared in water (first water). When preparing such a coprecipitate in water, a precursor that can be converted into a metal hydroxide and a rare earth element hydroxide, ie, a metal hydroxide precursor and a rare earth element hydroxide precursor, respectively A predetermined amount is dissolved in (preferably distilled water) to prepare an aqueous solution. The metal hydroxide precursor and rare earth element hydroxide precursor used here are the same as those used in step 1 of Method 1. The total concentration of these precursors in the aqueous solution is usually preferably set to 1% or less.
[0031]
Next, the pH of the aqueous solution thus obtained is adjusted to the alkaline side, and a metal hydroxide and a rare earth element hydroxide are simultaneously precipitated in water. Here, while the aqueous solution is usually stirred at 100 rpm or more, an alkaline aqueous solution, for example, a sodium carbonate aqueous solution or a sodium hydroxide aqueous solution of about 5% by weight is gradually and gradually dropped into the aqueous solution. Incidentally, in the case of the specific example, it is preferable to set the pH of the aqueous solution to 9.0 ± 0.2 over about 1 hour by such work.
[0032]
Process 2
In this step, the metal hydroxide and rare earth element hydroxide obtained in step 1 are converted into a metal oxide and a rare earth element oxide, respectively. Here, first, the aqueous solution in step 1 is filtered, and the coprecipitate formed in the aqueous solution is taken out. The coprecipitate is washed with ion exchange water or distilled water and then dried. Here, it is preferable to set the cleaning method and the drying method in the same manner as in step 2 of method 1.
[0033]
Next, the coprecipitate washed and dried as described above is activated. Here, the coprecipitate is gradually heated in an oxidizing atmosphere, for example, in air, and heat-treated at a constant temperature for several hours. Incidentally, in the specific example, the space velocity is 100 hr.^-1The coprecipitate is placed in an air atmosphere set to, and the temperature of the air atmosphere is heated to 450 ° C. at a temperature increase rate of 10 ° C./min. And a coprecipitate is continuously heat-processed at 450 degreeC for 4 hours.
[0034]
By such activation treatment, the metal hydroxide and the rare earth element hydroxide contained in the coprecipitate are converted into the metal oxide and the rare earth element oxide, respectively (in the specific example, iron hydroxide and lanthanum water). Each oxide is iron oxide (Fe₂O_Three) And lanthanum oxide (La₂O_Three), And usually a powdered oxide support is obtained.
[0035]
In addition, in this method, when manufacturing the catalyst for chlorinated organic compound decomposition | disassembly whose oxide support | carrier is complex oxide of a metal element and rare earth elements, the heating temperature at the time of the activation process in this process is set higher.
[0036]
Process 3
In this step, gold hydroxide is precipitated and precipitated in water containing the oxide carrier obtained in step 2 (second water). Here, first, the oxide carrier obtained in step 2 is put into water (preferably distilled water), and a precursor that can be converted into gold hydroxide is dissolved in the water. The precursor that can be converted to gold hydroxide used here is the same as that used in Step 1 of Method 1. The concentration of the precursor in water is usually preferably set to about 0.1 to 1.0% by weight.
[0037]
Next, the pH of the aqueous solution obtained as described above is adjusted to the alkaline side, and gold hydroxide is precipitated in water. Here, while the aqueous solution is usually stirred at 100 rpm or more, an alkaline aqueous solution, for example, a sodium carbonate aqueous solution or a sodium hydroxide aqueous solution of about 5% by weight is gradually and gradually dropped into the aqueous solution. Incidentally, in the case of the specific example, it is preferable to set the pH of the aqueous solution to 9.0 ± 0.2 over about 1 hour by such work.
In this step, the gold hydroxide is usually precipitated while being supported on the oxide carrier.
[0038]
Process 4
In this step, the gold hydroxide obtained in step 3 is converted to gold. Here, first, the aqueous solution in step 3 is filtered to take out the gold hydroxide together with the oxide carrier. Then, the oxide carrier carrying the gold hydroxide is washed with ion exchange water or distilled water and then dried. Here, it is preferable to set the cleaning method and the drying method in the same manner as in step 2 of method 1.
[0039]
Next, the gold hydroxide supported on the oxide carrier cleaned and dried as described above is activated. Here, the oxide carrier is gradually heated in an oxidizing atmosphere, for example, in air, and heat-treated at a constant temperature for several hours. Incidentally, in the specific example, the space velocity is 100 hr.^-1The oxide carrier is placed in an air atmosphere set to ≦ 3, and the temperature of the air atmosphere is heated to 450 ° C. at a temperature rising rate of 10 ° C./min. And an oxide support | carrier is continuously heat-processed at 450 degreeC for 4 hours.
By such activation treatment, the gold hydroxide supported on the oxide carrier is converted to gold, and the desired catalyst for decomposing chlorinated organic compounds is usually obtained in a powder form.
[0040]
Since the catalyst for decomposing chlorinated organic compounds of the present invention is such that gold fine particles are supported on the above-described oxide carrier, dioxins, and polychlorinated biphenyls (PCBs) that can be converted into dioxins, trichlorethylene In addition, various chlorinated organic compounds such as trichloroethane, dichloromethane, chlorophenols, chlorobenzene and other halogenated hydrocarbon compounds can be effectively oxidized and converted to non-toxic low molecular weight compounds.
[0041]
In particular, the catalyst for decomposing chlorinated organic compounds of the present invention can effectively oxidize and decompose gaseous chlorinated organic compounds. However, conventional catalysts have high decomposition activity for chlorinated organic compounds. The particulate chlorinated organic compound, which is difficult to decompose, can be effectively oxidized and decomposed simultaneously. For this reason, when the catalyst for decomposing chlorinated organic compounds of the present invention is used as a catalyst for treating exhaust gas generated from a garbage incinerator or various combustion apparatuses, dioxins in exhaust gas released into the atmosphere, etc. Concentration of several ng / Nm in terms of equivalent equivalent international toxicity^ThreeIt becomes easy to reduce below.
[0042]
  Using the catalyst for decomposing chlorinated organic compounds of the present inventionContained in exhaust gasWhen decomposing chlorinated organic compounds,Usually exhaust gas containing chlorinated organic compoundsIt processes in the high temperature atmosphere containing the catalyst of this invention. In this case, the temperature of the high temperature atmosphere is preferably set to at least 140 ° C., that is, 140 ° C. or higher. When this temperature is less than 140 ° C., the catalyst of the present invention may not exhibit effective decomposition activity,Contained in exhaust gasIt may be difficult to efficiently decompose chlorinated organic compounds.Note that the catalyst of the present invention uses exhaust gas.5,000 hr^-1While flowing at the above space velocity, the chlorinated organic compound contained therein can be contacted continuously for oxidative decomposition. That is, the catalyst of the present invention can continuously treat exhaust gas containing a chlorinated organic compound, and continuously decomposes the chlorinated organic compound contained in the exhaust gas to produce a non-toxic low molecular weight compound. Can be converted to
[0043]
【Example】
Example 1
Chloroauric acid (HAuCl_Four・ 4H₂O) 2.18 g, iron nitrate (Fe (NO_Three)_Three・ 9H₂O) 31.74 g and lanthanum nitrate (La (NO_Three)_Three・ 6H₂O) 7.14 g of each was dissolved in distilled water to prepare an aqueous solution having a total concentration of 1% by weight.
[0044]
While stirring the obtained aqueous solution at a stirring speed of 100 rpm, a 5 wt% sodium carbonate aqueous solution was gradually dropped into the aqueous solution over 1 hour, and the pH of the aqueous solution was set to 9.0. As a result, iron hydroxide, lanthanum hydroxide and gold hydroxide were precipitated and co-precipitated in the aqueous solution.
[0045]
The resulting coprecipitate was filtered and washed. Here, it was washed using ion-exchanged water until the sodium ion concentration in the washing liquid became 5 ppm or less. The coprecipitate after washing was placed in a drying oven set at 120 ° C. and dried until the water content was 10% by weight or less.
[0046]
Next, the coprecipitate after drying was activated. Here, the space velocity is 100 hr^-1The coprecipitate was heated to 450 ° C. at a rate of temperature increase of 10 ° C./min in the air set to 4 and the heat treatment was continued at that temperature for 4 hours. As a result, iron oxide (Fe₂O_Three) And lanthanum oxide (La₂O_ThreeA powdery catalyst for decomposing chlorinated organic compounds in which gold fine particles (average particle size = 25 nm) are supported on an oxide carrier comprising: In this catalyst, the constituent ratio of each component calculated from the amount of raw material used is 10.4% by weight of gold / (iron oxide + lanthanum oxide) and gold atom / (iron atom + lanthanum atom) of 5. 0 mol% and lanthanum oxide / (iron oxide + lanthanum oxide) were 30 wt% (17.36 mol%).
[0047]
Example 2
Iron nitrate (Fe (NO_Three)_Three・ 9H₂O) 31.74 g and lanthanum nitrate (La (NO_Three)_Three・ 6H₂O) 7.14 g of each was dissolved in distilled water to prepare an aqueous solution having a total concentration of 1%.
[0048]
While stirring the obtained aqueous solution at a stirring speed of 100 rpm, a 5 wt% sodium carbonate aqueous solution was gradually dropped into the aqueous solution over 1 hour, and the pH of the aqueous solution was set to 9.0. As a result, iron hydroxide and lanthanum hydroxide were precipitated and co-precipitated in the aqueous solution.
[0049]
The resulting coprecipitate was filtered and washed. Here, it was washed using ion-exchanged water until the sodium ion concentration in the washing liquid became 5 ppm or less. The coprecipitate after washing was placed in a drying oven set at 120 ° C. and dried until the water content was 10% by weight or less.
[0050]
Next, the coprecipitate after drying was activated. Here, the space velocity is 100 hr^-1The coprecipitate was heated to 450 ° C. at a rate of temperature increase of 10 ° C./min in the air set to 4 and the heat treatment was continued at that temperature for 4 hours. As a result, iron oxide (Fe₂O_Three) And lanthanum oxide (La₂O_ThreeAn oxide carrier consisting of
[0051]
Next, the total amount of the obtained oxide support and chloroauric acid (HAuCl_Four・ 4H₂O) 2.18 g was put into distilled water to prepare an aqueous solution having a concentration of 0.3% by weight of chloroauric acid. While stirring this aqueous solution at a stirring speed of 100 rpm, a 5 wt% sodium carbonate aqueous solution was gradually dropped into the aqueous solution over 1 hour, and the pH of the aqueous solution was set to 9.0. As a result, gold hydroxide was precipitated in the aqueous solution and was deposited on the oxide carrier.
[0052]
The aqueous solution thus treated was filtered to wash the oxide carrier. Here, it was washed using ion-exchanged water until the sodium ion concentration in the washing liquid became 5 ppm or less. The cleaned oxide carrier was placed in a drying furnace set at 120 ° C. and dried until the water content was 10% by weight or less.
[0053]
Next, the gold hydroxide supported on the oxide carrier after drying was activated. Here, the space velocity is 100 hr^-1The air was heated to 450 ° C. at a rate of temperature increase of 10 ° C./min, and the heat treatment was continued at that temperature for 4 hours. As a result, iron oxide (Fe₂O_Three) And lanthanum oxide (La₂O_ThreeA powdery catalyst for decomposing chlorinated organic compounds in which gold fine particles (average particle size = 25 nm) are supported on an oxide carrier comprising: In this catalyst, the composition ratio of each component calculated from the amount of raw material used is the same as that in Example 1.
[0054]
Evaluation
About each of the catalyst for chlorinated organic compound decomposition | disassembly obtained in Example 1 and Example 2, the decomposition activity with respect to dioxin standard goods was evaluated. Here, 4.0 g of the catalyst (bulk density = 1.013 g / cm for both the catalyst of Example 1 and the catalyst of Example 2)^Three) Of 8.0 g quartz sand (bulk density = 1.000 g / cm)^Three) To prepare a catalyst sample (volume = 12 ml). Then, this catalyst sample was filled into a reaction tube having an inner diameter of 8.8 mm so as to have a length of 62 mm, and 170 ng of a dioxin standard product was injected into the catalyst sample from the inlet side of the reaction tube. The standard dioxin used here is a hexane solution containing 7 types of polychlorinated dibenzo-para-dioxin isomers and 10 types of polychlorinated dibenzofuran isomers (dioxin concentration = 0.1 ng / μl). The above injection amount is a value in terms of dioxin amount. Hexane contained in the dioxin standard product was evaporated by flowing air at room temperature through the reaction tube.
[0055]
Next, a catalyst activity test apparatus as shown in FIG. 1 was assembled using the above-described reaction tube filled with a catalyst sample and a dioxin standard product. The catalytic activity test apparatus 1 mainly includes a tubular electric furnace 2, a preheating device 3, and an adsorption device 4. The tubular electric furnace 2 is configured so that the reaction tube 5 can be horizontally disposed therein, and is for heating the reaction tube 5 filled with the catalyst sample C. The preheating device 3 is for preheating the air sent into the reaction tube 5, and the outlet side of the air is connected to the inlet side of the reaction tube 5. The adsorption device 4 is for adsorbing and removing dioxins contained in the air discharged from the reaction tube 5 and includes an ice bath 6 and a glass tube 7 disposed therein. . The glass tube 7 is bent in a U shape in two stages, one end is connected to the outlet side of the reaction tube 5 and the other end is connected to the suction pump 8. A column 7a is attached to the second U-shaped bent portion of the glass tube 7 and is filled with XAD-2 resin 9 for adsorbing dioxins.
[0056]
The activity of the catalyst sample was examined using the catalyst activity test apparatus 1 described above. Here, the reaction tube 5 was gradually heated by the tubular electric furnace 2 while operating the suction pump 8 to suck in air, and set to a predetermined heating temperature. At this heating temperature, heating of the reaction tube 5 was continued for 4 hours. At this time, the air suction speed in the reaction tube 5 is such that the space velocity SV is 6,500 hr.^-1Set to be. Incidentally, this space velocity is relative to the total volume of the chlorinated organic compound decomposition catalyst and quartz sand contained in the catalyst sample.
In addition, the heating temperature of the reaction tube 5 was set to three types of 140 ° C., 170 ° C., and 200 ° C., and the activity of the catalyst sample was examined for each heating temperature.
[0057]
After the elapse of the above heating time, heating of the reaction tube 5 by the tubular electric furnace 2 was stopped, and the reaction tube 5 was naturally cooled. The suction pump 8 was stopped when the temperature of the reaction tube 5 decreased to 100 ° C.
[0058]
Next, the catalyst sample was taken out from the reaction tube 5, and the dioxins remaining there were extracted with toluene (hereinafter, the extract thus obtained is referred to as a toluene extract). On the other hand, the reaction tube 5 and the glass tube 7 were sufficiently washed with toluene, and dioxins adsorbed on the XAD-2 resin 9 were extracted with toluene (hereinafter referred to as the washing solution obtained here). The combination of the extract and the toluene cleaning solution). Then, the dioxins contained in the toluene extract and the toluene washing solution were respectively changed to Dec. 1, 1997 Ministry of Health and Welfare Notification No. 234 “Calculation Method of Dioxins Concentration” and Feb. 26, 1997, Eikan No. 38. No. “Dioxin Standard Analysis Manual for Waste Disposal” (Environmental Maintenance Division, Ministry of Health and Welfare, Ministry of Health and Welfare, February 1997), quantitative analysis was performed to determine the decomposition rate. In addition, the decomposition rate was calculated | required according to the following formula.
[0059]
[Expression 1]

[0060]
The results are shown in Tables 1-6. Tables 1, 2 and 3 show the results when the catalyst according to Example 1 is used, and show the results when the reaction tube 5 is heated at 140 ° C., 170 ° C. and 200 ° C., respectively. Yes. On the other hand, Tables 4, 5 and 6 show the results when the catalyst according to Example 2 is used, and show the results when the reaction tube 5 is heated at 140 ° C., 170 ° C. and 200 ° C., respectively. Yes. In each table, each abbreviation indicating dioxins represents the following compound. “TEF” indicates a toxicity equivalent coefficient, and “TEQ” indicates a toxic equivalent amount of a standard dioxin used.
PCDDs: Polychlorinated dibenzo-para-dioxins
T_FourCDD: Tetrachloride dibenzodioxin
P_FiveCDD: dibenzodioxin pentachloride
H₆CDD: hexachlorodibenzodioxin
H₇CDD: Dibenzodioxin chloride
O₈CDD: Dibenzodioxin octachloride
PCDFs: Polychlorinated dibenzofurans
T_FourCDF: Dibenzofuran tetrachloride
P_FiveCDF: Dibenzofuran pentachloride
H₆CDF: Dibenzofuran hexachloride
H₇CDF: Dibenzofuran heptachloride
O₈CDF: Dibenzofuran octachloride
[0061]
[Table 1]

[0062]
[Table 2]

[0063]
[Table 3]

[0064]
[Table 4]

[0065]
[Table 5]

[0066]
[Table 6]

[0067]
【The invention's effect】
  Since the catalyst for decomposing chlorinated organic compounds of the present invention is such that gold fine particles are supported on the oxide carrier as described above,Contained in exhaust gasIt can exhibit high decomposition activity for chlorinated organic compounds.
[0068]
  In addition, the method for decomposing chlorinated organic compounds according to the present invention uses the catalyst for decomposing chlorinated organic compounds of the present invention.Contained in exhaust gasThe chlorinated organic compound can be effectively decomposed.
[Brief description of the drawings]
FIG. 1 is a schematic view of a catalytic activity test apparatus used in the evaluation of Examples.

Claims (8)

A catalyst for decomposing chlorinated organic compounds contained in exhaust gas,
An oxide of at least one metal element selected from the group consisting of magnesium, aluminum, silicon, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten; An oxide support comprising at least one oxide of a rare earth element;
Gold fine particles having an average particle size of 30 nm or less supported on the oxide carrier;
A catalyst for decomposing chlorinated organic compounds.   The catalyst for decomposing chlorinated organic compounds according to claim 1, wherein the rare earth element is at least one selected from the group consisting of yttrium, lanthanum and cerium. The atomic ratio of the rare earth element to the metal element constituting the oxide support is 0.005 to 50, and the gold occupying in the total of the metal element, the rare earth element and the gold constituting the oxide support The catalyst for decomposing chlorinated organic compounds according to claim 1 or 2 , wherein the proportion of the atoms is 0.0005 to 0.2. A catalyst for decomposing chlorinated organic compounds contained in exhaust gas,
At least one metal element selected from the group consisting of magnesium, aluminum, silicon, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten, and at least one An oxide carrier composed of a complex oxide with a rare earth element of a kind,
Gold fine particles having an average particle size of 30 nm or less supported on the oxide carrier;
A catalyst for decomposing chlorinated organic compounds. A catalyst for decomposing chlorinated organic compounds contained in exhaust gas,
Hydroxide of at least one metal element selected from the group consisting of magnesium, aluminum, silicon, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten Obtaining a coprecipitate comprising at least one rare earth element hydroxide and a gold hydroxide in water;
The coprecipitate is taken out from the water, and the metal element hydroxide, the rare earth element hydroxide and the gold hydroxide contained in the coprecipitate are respectively converted into the metal element oxide and the rare earth element. Converting to oxide and gold;
A catalyst for decomposing chlorinated organic compounds obtained through a production process comprising: A catalyst for decomposing chlorinated organic compounds contained in exhaust gas,
Hydroxide of at least one metal element selected from the group consisting of magnesium, aluminum, silicon, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, indium, tin and tungsten And obtaining in the first water a coprecipitate comprising at least one rare earth element hydroxide;
The coprecipitate is taken out from the first water, and the metal element hydroxide and the rare earth element hydroxide contained in the coprecipitate are respectively the metal element oxide and the rare earth element oxide. A step of obtaining an oxide support by conversion into
Precipitating gold hydroxide in the second water containing the oxide carrier;
Removing the gold hydroxide together with the oxide carrier from the second water and converting the gold hydroxide to gold;
A catalyst for decomposing chlorinated organic compounds obtained through a production process comprising: A method for decomposing chlorinated organic compounds contained in exhaust gas,
A step of treating the exhaust gas in a high-temperature atmosphere containing the chlorinated organic compound decomposition catalyst according to claim 1 ,
Decomposition method of chlorinated organic compounds.   The method for decomposing a chlorinated organic compound according to claim 7, wherein the high-temperature atmosphere is set to at least 140 ° C.

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