JPH11216362A - Organochlorine compound removing catalyst and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and inexpensively remove an organochlorine compd. from gas. SOLUTION: A method for removing an organochlorine compd. from an organochlorine compd.-containing gas includes a process bringing the above mentioned gas into contact with a catalyst containing porous manganese oxide having an octahedral structure and molecular sieve action within a temp. range of 100-350 deg.C. Since porous manganese oxide is contained, the catalyst can be inexpensively provided as compared with a conventional noble metal catalyst and the organochlorine compd. can be efficiently removed from gas to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing an organic chlorine compound, and more particularly to a method for removing an organic chlorine compound using a catalyst.

[0002]

2. Description of the Related Art Exhaust gas discharged from an incinerator or the like contains various organic chlorine compounds. Such organic chlorine compounds can include dioxins and aromatic chlorine compounds that are considered to be precursors thereof, which are considered to have a serious adverse effect on the human body. There is a pressing need, and various methods are being studied for that purpose.

[0003] Methods of removing organic chlorine compounds proposed so far include, for example, a thermal decomposition method, an adsorption method and a catalytic decomposition method, but they can be carried out at a relatively low temperature. The catalytic decomposition method is recognized as the most practical method.

The catalytic decomposition method is a method in which a gas to be treated, such as an exhaust gas containing an organic chlorine compound, is brought into direct contact with a catalyst to thereby oxidize and decompose the organic chlorine compound. The catalyst to be used is mainly a metal oxide catalyst or a noble metal catalyst. However, metal oxide catalysts have insufficient decomposition activity for organic chlorine compounds, and it is difficult to efficiently remove the organic chlorine compounds from the gas to be treated. On the other hand, noble metal-based catalysts have remarkably high decomposition activity of organic chlorine compounds as compared with metal oxide-based catalysts, but are expensive and thus have limited practicality.

An object of the present invention is to realize a catalyst capable of removing an organic chlorine compound at low cost and efficiently.

Another object of the present invention is to efficiently and inexpensively remove an organic chlorine compound from a gas containing the organic chlorine compound.

[0007]

The catalyst for removing an organochlorine compound of the present invention contains a porous manganese oxide having an octahedral structure and a molecular sieve action.

Further, the method for removing an organic chlorine compound according to the present invention is a method for removing the organic chlorine compound from a gas containing the organic chlorine compound. This method
The method includes a step of bringing the above-mentioned gas into contact with a catalyst containing a porous manganese oxide having an octahedral structure and having a molecular sieve action in a temperature range of 100 to 350 ° C.

In this method, the oxygen concentration in the gas is set to, for example, 1 to 25% by volume, and the GHSV when the gas is brought into contact with the catalyst is, for example, 100 to 100,000 hr ^-1.
Set to.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Catalyst for Removing Organic Chlorine Compound The catalyst for removing an organic chlorine compound of the present invention contains a porous manganese oxide. The porous manganese oxide used here is a porous material having an octahedral structure and having micropores having a pore size similar to zeolite (usually 3 to 8 angstroms). It has. The specific surface area of such a porous manganese oxide is larger than that of other transition metal oxides due to the above-mentioned micropores, and is usually 1 μm.
00 m ² / g or more.

The above-mentioned porous manganese oxide used in the present invention is a known substance, for example, Science, Vol. 2
60,511 (1993) and US Pat. No. 5,523,509.
And the like. Although the structure of the porous manganese oxide is not particularly limited, it is considered that the structure can be represented by, for example, the following general formulas (1) and (2).

[0012]

Embedded image

In the general formula (1), A is a + 1, +2, +3
Or a +4 valence tunnel cation or a combination thereof, a is a numerical value in the range of 0 to 4, M is a + 1, +
B is a skeleton-substituted metal cation having a valence of 2, +3 or +4 or a combination thereof;
Indicates a numerical value of 0 or more. In the general formula (2), a is a numerical value in a range of 0 or more and 6 or less,
b represents a numerical value in the range of 0 or more and 12 or less, and the other is the same as in the case of the general formula (1).

In the general formulas (1) and (2), the tunnel cation related to A is, for example, selected from the group consisting of an alkali metal cation, an alkaline earth metal cation and a transition metal cation. Also,
The skeleton-substituted metal cation according to M is represented by III in the periodic table.
A, IVA, VA, VIA, VIIA, VIIIA, I
A transition metal selected from groups B and IIB. Specifically, for example, Mg, Fe, Co, Ni, Cu, T
i, V, Cd, Mo, W, Cr, Zn, La, Ir, R
n, Pd and Pt.

The above-mentioned porous manganese oxide used in the present invention can be prepared, for example, according to the method described in the above-mentioned literature. An example is as follows. First, a permanganate compound in an autoclave,
A mixed manganese compound and ion-exchanged water are mixed, and an alkali is added thereto to adjust the pH to about 10 to 14. The mixture is heated to about 110 to 180 ° C. with stirring and reacted for about 10 hours. The precipitate thus formed is filtered, washed with ion-exchanged water, and ion-exchanged with an aqueous magnesium chloride solution. When this is further heated at about 150 ° C. for 3 days, a target porous manganese oxide is obtained.

The catalyst for removing an organic chlorine compound according to the present invention is not particularly limited as long as it contains the above-mentioned porous manganese oxide. For example, the catalyst may be porous manganese oxide itself. Further, a carrier in which a porous manganese oxide is supported on a carrier, or a carrier in which these are mixed with a binder and formed into a desired shape can be used as the catalyst for removing an organic chlorine compound of the present invention. In addition, as a carrier for supporting the porous manganese oxide, for example, silica, alumina, titania and the like can be mentioned.

The exchangeable metal ions contained in the porous manganese oxide may be appropriately exchanged by other metal ions such as copper ions, iron ions, and cobalt ions.

When the catalyst for removing an organochlorine compound of the present invention contains other components such as the above-mentioned carrier and binder in addition to the porous manganese oxide, the content of the porous manganese oxide is at least 0.1% by weight or more. It is preferable to set so as to include. When the proportion of the porous manganese oxide is less than 0.1% by weight, the performance of removing the organic chlorine by the catalyst of the present invention may not be sufficiently exhibited.

The shape of the catalyst for removing an organochlorine compound of the present invention is not particularly limited. Can be set. In addition, the method for producing the catalyst having such various shapes is not particularly limited. For example, when the organic chlorine removal catalyst is formed in a honeycomb shape, the above-described carrier component,
Mixing the porous manganese oxide and the binder component,
A method of forming this into a honeycomb shape by a forming method such as an extrusion method, a method of impregnating a honeycomb-shaped substrate with a carrier component and a porous manganese oxide, or the like can be employed.

The catalyst for removing organochlorine compounds of the present invention can be provided at a lower cost than various noble metal catalysts used in conventional catalytic decomposition methods.

The method for removing an organic chlorine compound The method for removing an organic chlorine compound according to the present invention is a method for removing the organic chlorine compound from a gas containing the organic chlorine compound.

The gas to be treated according to the present invention (gas to be treated) is not particularly limited as long as it contains an organic chlorine compound. For example, general waste and industrial waste are incinerated. Exhaust gas generated at the time. Such exhaust gases include dioxins such as 2,3,7,8-tetrachlorodibenzodioxin and 2,3,4,7,8-pentachlorodibenzofuran and dioxins such as monochlorobenzene, dichlorobenzene and chlorophenol. Contains various organic chlorine compounds represented by precursors.

When the above-described gas to be treated is treated by the method of the present invention, the gas to be treated is brought into contact with the above-mentioned catalyst for removing an organic chlorine compound according to the present invention to be decomposed. At this time, the gas to be treated is preferably brought into contact with a catalyst for removing an organic chlorine compound under an oxidizing atmosphere. This can be achieved, for example, by setting the oxygen concentration in the gas to be treated to 1 to 25% by volume. When the oxygen concentration is less than 1% by volume, the organic chlorine compound contained in the gas to be treated is difficult to be efficiently oxidized and decomposed, and it becomes difficult to remove the organic chlorine compound from the gas to be treated. There is. Conversely, if the content exceeds 25% by volume, the decomposition activity may level off and dangerous peroxide may be generated.

The temperature during the above-mentioned processing is usually 10
Set to 0-350 ° C. When this temperature is lower than 100 ° C., the decomposition reaction of the organic chlorine compound does not easily proceed,
It becomes difficult to efficiently remove the organic chlorine compound from the gas to be treated. On the other hand, when the temperature exceeds 350 ° C., although the decomposition reaction of the organic chlorine compound proceeds rapidly, it is uneconomical due to an increase in heat consumption, and dioxin is regenerated from the decomposition product of the organic chlorine compound. Danger. The above-described processing may be performed in any environment under normal pressure, under pressure, or under reduced pressure.

Further, the GHSV at the time of the above processing is
(Gas hour space velocity) is usually 100
１００100,000 hr ⁻¹ , preferably 1,
More preferably, it is set to 000 to 50,000 hr ^-1 . When the GHSV is less than 100 hr ^-1 , it is necessary to use a large amount of the organochlorine compound removing catalyst of the present invention, which may increase the processing cost and become uneconomical. vice versa,
If it exceeds 100,000 hr ^-1 , the reaction conversion may be reduced.

In the method of the present invention, the above-mentioned porous manganese oxide, which can be provided at a relatively low cost, is used as a catalyst, and the gas to be treated is brought into contact with the catalyst in a specific relatively low temperature range. Organic chlorine compounds contained therein can be efficiently and inexpensively removed. In particular, the method of the present invention uses 0.05 to 500 ng / Nm in terms of dioxin (2,3,7,8-tetrachlorodibenzodioxin).
It is suitable for treating gas to be treated containing about ³ organic chlorine compounds, and is used to treat such exhaust gas generated during incineration of general waste and industrial waste, which is the gas to be treated. It is effective when done.

[0027]

EXAMPLE 1 50 parts by weight of potassium permanganate in an autoclave
50 parts by weight of manganese sulfate, 20 parts by weight of hydrogen peroxide and 400 parts by weight of ion-exchanged water were added and mixed, and the pH was adjusted to around 13 to 14 by adding an aqueous solution of sodium hydroxide. The mixture was heated with stirring and reacted at 150 ° C. for 10 hours to produce a layered precursor precipitate. The precipitate was separated by filtration, washed with ion-exchanged water, and allowed to stand at room temperature for 10 hours. Thereafter, the precipitate was ion-exchanged with magnesium chloride and further heat-treated at 160 ° C. for 3 days. As a result, a porous manganese oxide having an octahedral structure and having a molecular sieve action was obtained.

Next, a catalytic activity test was performed on the obtained porous manganese oxide. Here, first, the inner diameter is 10 m
m of a glass reaction vessel was prepared and filled with 1 cc of the obtained porous manganese oxide. Then, a nitrogen gas containing 0.3% by volume of monochloroanisole as an organic chlorine compound and 20% by volume of oxygen was supplied to the reaction vessel using a normal-pressure fixed-bed flow reactor, and reacted for 1 hour. At this time, the reaction temperature was set to 250 ° C., and the GHSV was set to 6,0.
00 hr ^-1 . When the components contained in the nitrogen gas treated with the porous manganese oxide in this way were analyzed by gas chromatography,
The conversion of monochloroanisole was 40%.

Example 2 A catalytic activity test was carried out in the same manner as in Example 1 except that the GHSV was changed to 1,000 hr ^-1 , and the conversion of monochloroanisole was 95%.

EXAMPLE 3 The reaction temperature and GHSV were
A catalytic activity test was conducted in the same manner as in Example 1 except that the conversion was changed to 000 hr ^-1 , and the conversion of monochloroanisole was 20%.

Example 4 The reaction temperature and GHSV were 200 ° C. and 1, respectively.
A catalytic activity test was conducted in the same manner as in Example 1 except that the conversion was changed to 000 hr ^-1 , and the conversion of monochloroanisole was 60%.

Comparative Example 1 A catalytic activity test was carried out on commercially available manganese oxide in the same manner as in Example 1, and the conversion of monochloroanisole was only 15%.

Comparative Example 2 A catalytic activity test was carried out on commercially available chromium oxide in the same manner as in Example 1, and the conversion of monochloroanisole was only 10%.

Comparative Example 3 A catalytic activity test was carried out on a commercially available vanadium oxide / titanium oxide / tungsten oxide denitration catalyst for exhaust gas in the same manner as in Example 1. As a result, the conversion of monochloroanisole was 20% or less. Was.

[0035]

The catalyst for removing organochlorine compounds of the present invention comprises:
Because it contains the above-mentioned porous manganese oxide,
The catalyst can be provided at a lower cost than conventional noble metal catalysts, and the organic chlorine compound can be efficiently removed from the gas to be treated.

In the method for removing an organic chlorine compound according to the present invention, since the gas to be treated is brought into contact with the catalyst for removing an organic chlorine compound according to the present invention, the organic chlorine compound contained in the gas to be treated is efficiently removed. And it can be removed at low cost.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Zhang Hanmin 17 Kyoto Research Park, Nakadoji Minamicho, Shimogyo-ku, Kyoto, Kyoto

Claims (4)

[Claims] 1. A catalyst for removing organochlorine compounds having a porous manganese oxide having an octahedral structure and having a molecular sieve action. 2. A method for removing an organochlorine compound from a gas containing the organochlorine compound, comprising: a catalyst containing a porous manganese oxide having an octahedral structure and having a molecular sieve action; A method for removing an organic chlorine compound, comprising a step of contacting the gas in a temperature range of 100 to 350 ° C. 3. The method according to claim 2, wherein the oxygen concentration in the gas is set at 1 to 25% by volume. 4. The GH for contacting the gas with the catalyst.
The method for removing an organic chlorine compound according to claim 2 or 3, wherein the SV is set to 100 to 100,000 hr ^-1 .