JP2903960B2 - Method for producing catalyst carrier for treating organochlorine compound, catalyst using obtained carrier, and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for treating an organic chlorine compound and, more particularly, to a method for producing a catalyst for catalytically decomposing chlorine in an organic chlorine compound.

[0002]

2. Description of the Related Art Organochlorine compounds such as trichlorethylene and tetrachloroethylene are widely used in metal degreasing and dry cleaning processes. However, since organochlorine compounds are carcinogenic substances, pollution by discharge into the air or elution into groundwater or soil has become a problem, and development of detoxification techniques for waste liquids and the like is desired. .

[0003] As a method for removing organic chlorine compounds in the atmosphere or waste liquid, for example, a method of adsorbing on activated carbon or zeolite is known. Various methods have been studied and proposed as a method of rendering the thus recovered organic chlorine compounds harmless. For example, a thermal decomposition method of burning an organic chlorine compound at a high temperature of 800 ° C. or higher, a method of irradiating the organic chlorine compound with ultraviolet rays, and decomposing the organic chlorine compound in plasma, and the like. However, all of these methods require a large-scale apparatus and increase processing costs.

On the other hand, the catalytic cracking method in which the catalyst is decomposed and burned in the presence of a catalyst is a simple method, and has recently attracted particular attention as a technique for decomposing and detoxifying organic chlorine compounds. For example, an organic chlorine compound in the presence of water vapor and oxygen at a temperature of about 400 to 500 ° C., alumina, silica, zeolite, titania, copper on an oxide carrier obtained by using an oxide alone or in combination with zirconia, This is a method in which a metal having a high oxidizing activity such as chromium, iron, platinum, and palladium is brought into contact with a catalyst in which the metal is supported as an active metal to perform decomposition treatment.

In the case of using a catalyst, generally, in a gas-based reaction, a high SV (gas flow rate per unit time / catalyst volume),
The reaction is performed under conditions of high LV (linear velocity), and it is considered that the larger the specific surface area of the catalyst used in the reaction, the more desirable. In addition, since the reactant is an organic chlorine compound and hydrochloric acid is generated as a reaction product, it is important that the acid resistance, particularly the hydrochloric acid resistance, be excellent. However, among the oxides used for the above-mentioned carriers, those having excellent acid resistance are only titania and zirconia. But,
The catalyst carrier prepared with titania or zirconia usually has a small specific surface area, and thus has a problem that although the initial activity is high, the activity cannot be maintained for a long period of time. For this reason, development of a catalyst carrier suitable for catalytic cracking of organic chlorine compounds having acid resistance and a high specific surface area is desired.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended for use in decomposing and removing a gas containing an organic chlorine compound such as trichloroethylene and tetrachloroethylene in the presence of oxygen and water using a catalyst. An object of the present invention is to provide a method for producing a carrier for a catalyst that can maintain the activity for a long period of time with high decomposition efficiency, a catalyst using the obtained carrier, and a method for producing the same.

[0007]

According to a first embodiment of the present invention for solving the above-mentioned problems, an aqueous solution containing SiO ₂ is dropped into a slurry obtained by mixing an aqueous solution of aluminum sulfate and an aqueous solution of sodium aluminate. The silica-alumina hydrate cake was obtained by filtration and washing to prepare a silica-alumina hydrate cake, and boric acid was added to the silica-alumina hydrate cake, followed by heating and kneading, followed by molding and drying. And then calcining to obtain a catalyst carrier for treating the organochlorine compound.
It is characterized by a method for producing a catalyst carrier having a crystal form of mullite and aluminum borate structure at a temperature of 0 to 1100 ° C. and a specific surface area of 100 m ² / g or more. In the second embodiment, boron is ₃ as B ₂ O 3.
10 to 10% by weight, 4 to 19% by weight of silica as SiO ₂
And a carrier comprising a boria-silica-alumina composition having a mullite and aluminum borate structure in crystal form and having a specific surface area of 100 m ² / g or more, comprising 0.1 to 5% by weight based on the carrier. And a catalyst for treating an organochlorine compound carrying platinum or platinum-cobalt as an active metal. Further, a third embodiment includes:
Boron is ₃ to 10% by weight as B ₂ O ₃ , silica is Si
It contains 4 to 19% by weight as O ₂ , the crystal form is mullite and aluminum borate structure, and the specific surface area is 100
m ² / g or more of a boria-silica-alumina composition and 0.1 to 5% by weight of the support
A method for producing a catalyst for treating an organochlorine compound is obtained by impregnating a solution containing platinum or platinum-cobalt to be obtained, followed by firing at 400 to 600 ° C. to obtain a catalyst for treating the organochlorine compound.

[0008]

According to the present invention, when a composite oxide having a morphology of mullite and an aluminum borate structure is used as a carrier for a catalyst, the carrier exhibits extremely high acid resistance.

The catalyst support of the present invention has excellent acid resistance to hydrogen chloride because the boria-silica-alumina composite oxide has a mullite (Al ₆ Si ₂ O ₁₃ ) structure and aluminum borate (Al ₁₈ B ₄ O ₃₃ ) structure together with an orthorhombic crystal structure, and is formed from two complex oxides,
It is considered that excess alumina dissolves in the mullite, boria is uniformly arranged in the excess alumina skeleton, and an aluminum borate phase is formed, thereby exhibiting acid resistance. In the catalyst carrier of the present invention, the content of boron is ₃ to 10% by weight as B ₂ O _{3 and the} content of silica is 4 to 19% by weight as SiO _2. And a structure such as aluminum borate is not adopted. The reason why the specific surface area of the catalyst carrier is 100 m ² / g or more is to achieve high activity.

As the active metal used in the present invention, it is necessary to use platinum or platinum-cobalt, and the loading of the active metal is in the range of 0.5 to 5% by weight. If the amount is too small, sufficient activity cannot be obtained, while if the amount is large, no further effect on the activity improvement can be obtained, and the economical efficiency is rather deteriorated.

In order to obtain the catalyst carrier and the catalyst of the present invention, basically, an aqueous solution of aluminum sulfate and an aqueous solution of sodium aluminate described in JP-A-3-217232 are mixed, and the mixture is hydrolyzed. A predetermined amount of an aqueous solution of sodium silicate was added to the alumina hydrate slurry thus obtained, followed by filtration and filtration.
Washing to obtain a silica-alumina hydrate, adding a predetermined amount of boric acid aqueous solution to the hydrate, kneading to a moldable moisture to form a desired shape, drying, and then firing The method for obtaining a catalyst carrier can be used, and the obtained catalyst carrier is impregnated with a solution containing a noble metal alone or in combination with a noble metal and a transition metal in an amount of 0.15 to 5% by weight based on the carrier as an active metal, It is dried at a temperature of 80-110 ° C, and the obtained dried product is
A method of producing a catalyst by firing at a temperature of 00 to 600 ° C can be applied.

However, a feature of the method of the present invention is that the calcination temperature for obtaining the catalyst carrier is limited to 1000 to 1100 ° C. That is, in the method described in the above publication, heat resistance is obtained by firing at a high firing temperature of 1200 ° C. or more, and the effect of the firing temperature below 1200 ° C. is not mentioned at all. The method of the present invention uses a calcination temperature of 100
By limiting the crystal form of the catalyst carrier to mullite and aluminum borate structure by limiting the range to 0 to 1100 ° C,
In addition, the specific surface area can be set to 100 m ² / g or more. That is, at a firing temperature of less than 1000 ° C., a support consisting of mullite and an aluminum borate structure cannot be obtained, and at a firing temperature of more than 1100 ° C., the specific surface area decreases and the activity decreases.
It is necessary to be in the range of 1100 ° C.

The thus produced catalyst for treating an organochlorine compound of the present invention can be used in a metal degreasing step or a dry cleaning step.
It is an effective catalyst for oxidizing and decomposing organic chlorine compounds such as exhaust gas and waste liquid discharged from a polishing step and the like to make them harmless.

[0014]

Next, an embodiment of the present invention will be described. (Example 1) (1) Preparation of a catalyst carrier 49.5 l of water was placed in a 100 l stainless steel reaction tank equipped with a stirrer.
And 9540 g of an aluminum sulfate aqueous solution containing 774 g as Al ₂ O ₃ was added thereto, and the mixture was heated to 70 ° C., kept, stirred, and dropwise added with an aqueous sodium aluminate solution containing 1275 g as Al ₂ O ₃ while stirring. An alumina hydrate slurry having a pH of 9.0 was obtained. Next, after aging the slurry for 30 minutes,
The slurry - in the 6.4 to pH adding 30% strength nitric acid 50 g, then stirring was added dropwise a sodium silicate aqueous solution 1820g containing 255g as SiO ₂ while the silica having a pH of 8.5 - obtain alumina mixture hydrate and then the slurry - after aging for 30 minutes, filtered, washed, 11.0 wt% as SiO _2, 0.1 wt% as Na ₂ O, 0.5 wt.% as SO ₄
Containing silica-alumina hydrate cake.

Next, the silica-alumina hydrate cake 25
42 g of boric acid in 00 g (450 g as SiO ₂ -Al ₂ O ₃ )
(23.7 g as B ₂ O ₃ ), and kneaded by heating in a kneader equipped with a heating jacket to obtain a plastic kneading having a B ₂ O ₃ —SiO ₂ —Al ₂ O ₃ concentration of 39% by weight. I got something. This kneaded product is molded by an extrusion molding machine having a die having a diameter of 1.5 mm, dried at 110 ° C. for 18 hours, and 1000 ° C. in an electric furnace, and 1
Baking at 100 ° C. for 3 hours for 5% as B ₂ O ₃ , S
boria as iO ₂ containing 10.5 wt% - Silica - obtain a carrier for alumina catalyst A and the carrier B. In addition, the silica-alumina hydrate cake 2500 g (SiO ₂ —Al ₂ O ₃
50 g) except that the addition of 88.5g of boric acid (50.0 g as B ₂ O ₃₎ in boria - silica - 10% by weight B ₂ O ₃ and how to obtain an alumina catalyst carrier A in substantially the same manner, SiO
_{As a result} , a carrier C for boria-silica-alumina catalyst containing 9.9% by weight as ₂ was obtained.

Next, the SiO ₂ solution to be added to the alumina hydrate slurry obtained in the
Sodium silicate aqueous solution 771 containing 14% by weight as O ₂
g (S with respect to Al ₂ O ₃ in alumina hydrate slurry)
559% by weight as iO ₂ ), and 3659 g ( ₂ as SiO _{2 with} respect to Al ₂ O ₃ in the alumina hydrate slurry)
0% by weight) and 5% by weight as B ₂ O _{3 and} 4.% as SiO _{2 in} the same manner as the method for obtaining the catalyst carrier A.
A boria-silica-alumina catalyst support D containing 8% by weight and a boria-silica-alumina catalyst support E containing 5% by weight as B ₂ O ₃ and 19.0% by weight as SiO ₂ were obtained.

The resulting catalyst carrier A, B, C, D, respectively the specific surface area of the ^{E 125m 2 / g, 103m 2} / g, 117m 2 /
g, 108 m ² / g and 119 m ² / g, and the crystal form was examined by X-ray diffraction. As a result, it was found that each was formed of two composite oxides having a mullite structure and an aluminum borate structure.

(2) Acid Resistance Test 400 ml of pure water was added to a 500 ml beaker, heated to 80 ° C., held, and stirred, and the catalyst carrier A was pulverized to 100 mesh or less to obtain a powder. Was added to 60 ml of a hydrochloric acid having a concentration of 36% to obtain a slurry having a pH of 0.1. The slurry was maintained for 10 hours while stirring, cooled, and then filtered, and the chlorine content was completely removed with pure water. And dried at 110 ° C for 15 hours.
After firing at 0 ° C. for 2 hours, the specific surface area was measured. The obtained specific surface area was 124 m ² / g, which was almost unchanged. Next, the same treatment is performed using the catalyst carrier C,
When the specific surface area after the treatment was measured, the specific surface area was 117 m ² /
g and had not changed.

(3) Preparation of Catalyst 1.7 g of cis-dinitrodiamineplatinum (II) salt (60.7% by weight as Pt) was added to 100 g of each of the catalyst carriers A, B, C, D and E obtained in the above carrier preparation. In 60 ml of water, dried at 110 ° C. for 15 hours, and then dried at 500 ° C. for 2 hours.
After calcining for hours, catalysts AC, BC, CC, DC and EC were obtained. The properties are shown in Table 1. Subsequently, 1.2 g of cobalt nitrate hexahydrate and cis-dinitrodiamine platinum (I
I) Impregnated with a solution of 1.2 g of salt (60.7% by weight as Pt) dissolved in 60 ml of water, dried at 100 ° C. for 15 hours, and then dried at 500 ° C.
For 2 hours to obtain a catalyst FC. The properties are also shown in Table 1.

(4) Activity evaluation Each of the catalysts AC to FC was crushed and sieved to obtain particles having a particle size in the range of 500 to 840 μm. The reaction was carried out using a fixed bed flow reactor having a catalyst loading of 10 ml. At a gas temperature of 500 ° C, trichlorethylene: 0.03 ml / min, water:
The catalyst gas was passed through the catalyst layer at a flow rate of 0.043 ml / min, air: 500 ml / min, SV: 5000 H ^-1 , and the processing gas was analyzed by gas chromatography using a gas chromatograph manufactured by Shimadzu Corporation. The results of activity evaluation 100 hours after the start of the reaction are also shown in Table 1.

Comparative Example 1 (1) Preparation of Catalyst Carrier Silica-alumina hydrate cake 2500 obtained in Example 1
g (450 g as SiO ₂ -A ₂ O ₃ ) with boric acid
6.2 g _(9.2 g as B 2 _{O 3),} and 141.0
g (79.4 g as B ₂ O ₃ ) in the same manner as in the preparation method of the catalyst carrier of Example 1 except that the catalyst carrier G was added.
And H were obtained. B ₂ O ₃ in the catalyst carrier G is 2% by weight,
SiO ₂ is 10.8% by weight, and B in the catalyst support H
₂ O ₃ was 15% by weight and SiO ₂ was 9.4% by weight.

Further, the obtained catalyst carrier G, specific surface area of the H are each ^{96m 2 / g, 88m 2 /} g, a crystalline form X
According to a diffraction analysis, the catalyst support G was formed of a composite oxide having a mullite structure and an aluminum borate structure and a θ-alumina structure, and the catalyst support H was formed of a composite of a mullite structure and an aluminum borate structure. It was formed of an oxide and a boron oxide structure.

(2) Acid Resistance Test An acid resistance test was performed on the catalyst carriers G and H in the same manner as in Example 1. It is found, the specific surface area of the catalyst carrier G and H are each ^{87m 2 / g, 79m 2 /} g, both have decreased, in the range of compositions of the present invention the acid resistance is insufficient I understood.

(3) Preparation of catalyst The catalyst was prepared in the same manner as in Example 1 using the catalyst carriers G and H.
GC and HC were obtained. The properties are also shown in Table 1.

(4) Activity evaluation The catalyst GC and HC activities were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

From Table 1, it is clear that the catalysts GC and HC whose compositions of the boria-silica-alumina catalyst support are out of the range of the present invention have low trichlorethylene treatment rates. Further, although the catalyst FC is a catalyst supporting platinum and cobalt, it is clear that the treatment efficiency of trichlorethylene is high by supporting a noble metal and a transition metal as active metals.

[0027]

[Table 1]

As described above, according to the present invention, a catalyst carrier having excellent acid resistance and a specific surface area of 100 m ² / g or more can be obtained, and a catalyst capable of treating an organic chlorine compound for a long period of time with high activity. And a method of manufacturing the same. Therefore, the catalyst of the present invention can realize detoxification by oxidative decomposition of an organic chlorine compound contained in exhaust gas, waste liquid, and the like discharged from a metal degreasing step, a dry cleaning step, and the like, and is extremely effective in environmental pollution prevention measures.

Claims (3)

(57) [Claims] 1. A slurry obtained by mixing an aqueous solution of aluminum sulfate and an aqueous solution of sodium aluminate is mixed with SiO ₂
Is added dropwise to obtain a silica-alumina mixed hydrate, which is filtered and washed to prepare a silica-alumina hydrate cake, boric acid is added to the silica-alumina hydrate cake, and the mixture is heated and kneaded. Molding, drying and then firing to obtain a catalyst carrier for treating an organochlorine compound, wherein the firing temperature is from 1000 to 1100 ° C.
A method for producing a catalyst carrier, wherein the crystal form is a mullite and aluminum borate structure, and the specific surface area is 100 m ² / g or more. 2. A composition containing ₃ to 10% by weight of boron as B ₂ O _{3 and} 4 to 19% by weight of silica as SiO ₂ , a crystal form of mullite and aluminum borate structure, and a specific surface area of 100 m ² / g. Boria-silica-
A carrier made of an alumina composition, 0.1
A catalyst for treating an organochlorine compound, wherein platinum or platinum-cobalt in an amount of up to 5% by weight is supported as an active metal. 3. A composition containing ₃ to 10% by weight of boron as B ₂ O _{3 and} 4 to 19% by weight of silica as SiO ₂ , a crystal form of mullite and aluminum borate structure, and a specific surface area of 100 m ² / g. Boria-silica-
A catalyst carrier comprising an alumina composition is impregnated with a solution containing platinum or platinum-cobalt in an amount of 0.1 to 5% by weight based on the carrier, and then calcined at 400 to 600 ° C. for treating an organic chlorine compound. A method for producing a catalyst for treating an organochlorine compound, characterized by obtaining a catalyst.