JPS58214341A - Catalyst for purifying noxious gas - Google Patents

Abstract

PURPOSE:To obtain the economical catalyst of practical use for purifying noxious gas, by forming manganic slag by-produced in the preparation of potassium permanganate or the mixture of the manganic slag and a caking agent. CONSTITUTION:Manganic slag by-produced in the preparation of potassium permanganate or the mixture of the manganic slag and a caking agent is formed to make the catalyst for purifying noxious gas. As said caking agent, one or more selected from clay minerals, cement, silicic acid or its salts, slaked lime, gypsum, diatom and alumina may be used. If the content of the manganic slag in the catalyst is below 50wt%, the power of purifying gas is unfavorably lowered. A proper temp. for removing noxious gas is at 150-1,000 deg.C for CO, 150-1,000 deg.C for hydrocarbon, a room temp. -1,000 deg.C for SO2 or 70-480 deg.C for nitrogen oxide. The ratio of the removal is excellent in any case, i.e. at 70-100%.

Description

[Detailed description of the invention] The present invention relates to a catalyst for purifying harmful gases.

More specifically) 1' and 1. Carbon monoxide (co) is generated from internal combustion engines, heating equipment, etc. when fuel is combusted.

Purify gases containing harmful substances such as hydrocarbons (HC), sulfur dioxide gas (SO2), and nitrogen oxides (N(']X)/I
! The object of the present invention is to provide an economical and highly practical catalyst consisting of manganese slag alone or a binder together with manganese slag, which is a by-product during the production of potassium permanganate having i-character.

Conventionally, carbon monoxide, hydrocarbons, carbon dioxide, sulfur dioxide, etc. contained in exhaust gas from internal combustion engines, combustion gas from heating equipment, etc.
- Typical catalysts proposed as catalysts for purifying gases containing harmful substances such as nitrogen oxide are as follows. First, electrolytic manganese dioxide (
γ-Mn(')2), iron oxyhydroxide (Fe00H),
Three components of basic copper carbonate, such as manganese oxide, iron oxide, and copper oxide, are kneaded together with alumina cement, and after curing in water and steam,
A catalyst prepared by heat treatment at 0 to 600°C for about 5 hours (Japanese Patent Application Laid-Open No. 54-26984), and a catalyst whose surface is coated with a platinum group metal such as platinum, palladium, ruthenium, or rhodium. There is a way to use θmi (Secret Kai No. 53-142993) blue.

However, the above method requires the use of oxides of platinum group metals, and also requires curing in water and steam, heat treatment at commercial temperatures, etc., resulting in a complicated process and a cost penalty. Moreover, the obtained catalyst has a working temperature range (250~
65 oc) is limited, and when the temperature for one history exceeds 650 oc, the purifying effect is rapidly lost. Furthermore, although the above method can oxidize carbon monoxide and hydrocarbons by using a noble metal catalyst such as platinum or palladium, it is disadvantageous in that it is oxidized and is susceptible to catalyst poisoning.

As a result of intensive research to eliminate the drawbacks of conventional catalysts, the present invention has developed an economical catalyst that maintains high activity in a wide temperature range from low to high temperatures, has excellent mechanical strength, 111141, and durability. It was discovered that manganese slag, which is a by-product during the production of potassium permanganate, is suitable as a catalyst for purifying harmful gases, leading to the completion of the present invention.

That is, the present invention is a catalyst for forming a harmful gas formed by molding manganese slag alone or the manganese slag and a binder, which are produced as a by-product during the production of potassium permanganate.

The manganese slag used in the present invention is produced by adding caustic potassium to manganese ore, oxidizing and roasting it while passing air to create potassium manganate, which is extracted with water and electrolytically oxidized to produce potassium permanganate. It is a by-product as extraction residue.

The composition of this manganese slag is roughly as shown in Table 1.

Table 1 % indicates the weight of the vehicle, and the composition is expressed as an oxide.

The self-harming scum that is purified by manganese slag with such a composition is i-carbon and hydrocarbons.

Examples include sulfur dioxide and concentrated oxides.
All harmful gases are rendered harmless by the manganese slag of the present invention acting as an oxidation catalyst, and the mechanism of action is as follows.

The reason for the significant reduction in carbon monoxide (CO) contained in self-harmful gas is the MnO2 and F'e contained in manganese slag.
203, At203.5i02, etc. are oxidized and roasted in the presence of caustic potash in a highly oxidizing atmosphere of the culm, and then moderately hydrolyzed to become active oxyhydroxides, This is combined with some of the slaked lime and caustic potash added during the production of permanganate acid. l! This is thought to be because carbon monoxide is oxidized to carbon dioxide gas (C02) by exerting a mediating effect.

Hydrocarbons such as ethylene contained in harmful gases can be considered in the same way as carbon monoxide.

Sulfur dioxide (802) contained in the harmful gas reacts with slaked lime [Ca(OH)2:l] in the manganese slag, calcium carbonate (CaC03), and oxygen (02) in the air to form calcium sulfate (CaSO4).

Oa((')H)2 +s02+ '5'-z 02
= CaSO4+ H20CaOO3+ 802 +
/202 = 0aSO4+ 002 Also, nitrogen monoxide (NO) contained in the harmful gas reacts with manganese dioxide (MnO2) in the manganese slag and oxygen (0□) in the air to form manganese nitrate (Mn(No3)2') It is considered that

2NO+ MnO2+02 = Mn (NO3)2 Each component in the above composition of manganese slag acts as an oxidation catalyst for carbon monoxide and hydrocarbons, solidifies sulfur dioxide and nitrogen monoxide through chemical reaction, and stabilizes them. The present invention is characterized by easily rendering the above-mentioned harmful gas harmless.
In order for this effect to be effectively achieved, it is necessary that the yield of manganese slag falls within the range shown in Table 1, and if it deviates from this range, the effects of the present invention cannot be expected.

The manganese slag used in the present invention originally has a powder diameter (1,1 to
Since it is in the form of a colloid with a diameter of 0,001 μm, it is fine and has a large specific surface area, making it advantageous as a catalyst. Therefore, it is possible to use it as it is as a raw material, or it can be dried and pulverized and used again as a raw material. In this case, it is necessary to pulverize it to eliminate the influence of secondary coagulation, and it is preferable to pulverize it to 60 mesh and use it once.

However, depending on the purpose of use, fine powdered manganese slag has low mechanical strength, so a binder is added to give it strength, and by shaping and drying it, it becomes spherical.
By processing it into various shapes such as pellets, rods, or honeycomb shapes, it can be made into a sentry medium with excellent catalytic performance, service life, and mechanical strength.

The binders used in the present invention include natural bentonite, acid clay, kaolinite, clays such as various glazed clays, cements such as alumina cement, blast furnace cement, and Portland cement, silicic acid, and silica sand. , silicic acid or its salts such as tobermorite, permolite, zeolite, allophane, alkaline earth metals such as slaked lime, magnesium hydroxide, gypsum, diatomaceous earth, and alumina, or a mixture of two or more thereof. used.

Among the above-mentioned various binders, clayey ones such as bentonite and acid clay are particularly effective in improving the formability and mechanical strength of the catalyst, extending the life of the catalyst, and increasing the surface area. In this case, alumina cement is preferable because its action is as good as that of clay, and it also has higher thermal strength.

The catalyst of the present invention is produced by mixing fine manganese slag and a binder, which are used as sub-74H during the production of potassium permanganate, and kneading the mixture with water. It can be easily obtained by molding into a desired shape such as a honeycomb shape and drying.

The catalyst of the present invention is preferably a composition consisting of 50 to 100% by weight of manganese slag and the remainder is a binder, and if the amount of manganese slag is less than 50% by weight, the purification performance of the harmful gas tends to decrease, so it is preferable. do not have.

The thus obtained catalyst for purifying harmful gases of the present invention has excellent temperature characteristics and exhibits high catalytic activity over a wide range of temperatures.
, jll can be held, and a specific example is shown below.
The optimum temperature for removing harmful gases is 50 to 1000 for carbon monoxide.
℃ or higher, 150 to 1000℃ or higher for hydrocarbons, room temperature to 1000℃ for sulfur dioxide, nitrogen oxide (No.
), the removal rate is good at 70 to 100% in all cases at 70 to 480C. .

Below, the effects of the present invention are listed.

(1) Conventional catalysts (oxidation catalysts) for purifying harmful gases had to use expensive metal oxides and precious metals, but with the present invention, they can be used to produce potassium permanganate. Since the resulting by-product manganese slag can be used effectively, it is extremely economical and highly practical.

(After manufacturing and molding the 2111I!14 medium, there is no need for special curing or heat treatment, and it can be easily produced and does not require advanced technology.

(3) In terms of catalytic performance, the removal effect of carbon monoxide, hydrocarbons, sulfur dioxide, -nitrogen oxide, etc. contained in harmful gases is effective over a wide range at high temperatures rather than low temperatures, and the applicable temperature range is wide.

(4) Even when used at high temperatures, no collapse or deterioration of the catalyst itself is observed, and there is almost no concern about contamination of reactants.

(5) Even if it is reused, there is little deterioration in catalyst performance, and it can be used repeatedly.

(6) Exhaust gas from internal combustion engines such as automobiles, petroleum gas)
Harmful components such as carbon monoxide, hydrocarbons, sulfur dioxide gas, and nitrogen oxide (NOx) contained in combustion gas from heating appliances such as smoked charcoal and smoked charcoal can be catalytically purified and converted into harmless gases.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Example 1 By-product manganese slag was dried and crushed to 60 mesh or less. -1 Natural bentonite 2811 water 1
40rnQ was collected and granulated with a well-mixed push-pull molding machine to a size of 3ν in diameter and 10 to 20 ML in length, and then dried and adjusted at 120C for about 10 hours. The strength of each columnar granule was 5.5 kg and 7 particles. Approximately 85 grams of the catalyst granules were packed into the combustion tube 1 of the catalyst testing device shown in Figure 1, and the catalyst body was fixed with glass wool 3 at both ends. The filled combustion tube is placed in a horizontal heating furnace 4, and while being heated to a constant temperature, a sample gas from a standard gas cylinder 5 is diluted with a popular gas from an air pump 6 and supplied at a constant flow rate via a flow meter 7, and heated. A portion of the gas from gas outlet 8 and gas outlet u9 was transferred to an analyzer (not shown) using a silicon gas tank, and a portion of the gas was transferred to an analyzer (not shown) through a switching cock 1o. The removal rate was measured by analyzing the concentration of each gas.

In this case, the space velocity of the processing gas Sv (](r')
was set to -, the reaction temperature was selected from room temperature to 1000'C, and the relationship between crystallinity 11 degrees and removal rate was determined.

Figure 2 shows the removal rate at each temperature when air containing carbon monoxide at a population concentration of 750 ppm was used as the supply gas for one period.

FIG. 3 shows the removal rate at various temperatures when air containing ethylene with a population of mWjOOppm was used as the supply gas.

FIG. 4 shows the removal rate at each zelkova temperature when one liter of air containing 100 ppm of nitric oxide at the inlet concentration was used as the supply gas.

The removal rate at each temperature when air containing nitrogen monoxide with a population concentration of 50 ppm is used as the supply gas is
Shown in the figure.

In FIGS. 1 to 5, curve A is the result of Example 1.

Comparative Example 1 By-product manganese slag as an active component of catalyst] A cylindrical granule was prepared in the same manner as in Example 1 using only naturally produced bentonite as a raw material, and the same catalyst test as in Example 1 was carried out. The relationship between temperature and removal rate using the apparatus is shown in curve B in FIGS. 2 and 4. Note that the inlet concentration of the supply gas was the same as in Example 1.

As a result, it was found that using manganese slag was more effective in removing harmful substances.

Example 2 After kneading only by-product manganese slag with water, cylindrical granules were prepared in the same manner as in Example 1 to prepare a catalyst.

A purification test was carried out on a feed gas containing C-carbon oxide as a harmful gas component and having the same population concentration as in Example 1 by using the same catalyst as in Example 1. The relationship between temperature and removal rate is shown in curve C in FIG.

Example 3 A mixture of by-product manka slag, which is the same raw material used in Example 1, and naturally produced bentonite as a binder at a ratio of 5:5 by volume was kneaded with water, and then formed into a cylindrical shape. The granules were adjusted and processed to make a catalyst. Using this catalyst, carbon monoxide is included as a harmful gas component, and the concentration is 1" in Example 1.
The same feed gas purification test was conducted. The relationship between temperature and removal rate is shown in curve 1 in Figure 2.

Example 4 Alumina cement was used instead of the naturally produced bentonite used in Example 1, and a mixture of by-product manganese slag and alumina cement at a weight ratio of 2:1 was kneaded with water and then formed into a cylindrical shape. A catalyst was made by creating granules. The strength of each cylindrical granule was 1.2 Kq 7 grains.

The above cylindrical granules were brought into contact with a supply gas containing carbon monoxide as a harmful component and having the same concentration as in Example 1 to determine the relationship between temperature and removal rate. .

The results are shown in curve E in Figure 2.

Example 5 A spherical catalyst with a diameter of 5 mm was prepared using the same catalyst components and raw materials in the same mixing ratio as in Example 4. This was brought into contact with a supply gas containing carbon monoxide as a harmful component and having the same human UA as in Example 1 in the same manner as in Example 1, and the relationship between temperature and removal rate was determined. Similar results were obtained.

Example 6 A honeycomb-shaped catalyst was prepared using the same catalyst components and blending ratio as in Example 4. Using the same method as in Example 1, this was brought into contact with a supply gas containing carbon monoxide and arsenic as harmful components and having the same concentration as in Example 1, and the relationship between 211u'1 degrees and the removal rate was determined. As a result, good results similar to curve E in FIG. 2 were obtained. After cooling, the temperature was raised to 2M degrees again and the oxidation rate was determined, but the catalyst performance did not deteriorate from the beginning and the reproducibility was good.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the catalyst test device for purifying harmful gases of the present invention, and Fig. 2 is an explanatory diagram of the catalyst testing device for purifying harmful gases of the present invention.
Figure 3 is a graph showing the catalytic effect showing the relationship between temperature and removal rate for ethylene, and Figure 4 is a graph showing the catalytic effect showing the relationship between temperature and removal rate for sulfur dioxide. A graph showing the catalytic effect showing the relationship between
FIG. 5 is a graph showing the catalytic effect showing the relationship between temperature and removal rate for phosphor monoxide. 1. Porcelain combustion tube, 2. Catalyst filling section, 3. Glass wool for solidifying the catalyst, 4. Horizontal heating furnace, 5. Standard gas cylinder,
6...Air pump, 7...Flow meter, 8...Gas person to combustion pipe 1-1.9...Gas outlet from combustion pipe, 10
...Application for switching cock for inlet and outlet gas concentration measurement
Person ] 2] Hon Kagaku Kogyo Co., Ltd. Minister Representative Yutaka 1) Zen
Figure 1 Figure 2 Figure 3 Humidity C)

Claims (3)

[Claims] (1) A toxic gas purifying medium made by molding manganese slag alone or a binder with the manganese slag produced as a by-product during the production of potassium permanganate. (2) Patent A in which the caking i1J is one or more selected from clay minerals, cement, silicic acid or its salts, /l'l right ash 2 lime 2 stones, lithium ash, and alumina? The catalyst for purifying harmful gases according to item 1. (3) Self-harmful gases such as carbon monoxide, hydrocarbons, and 117 dioxide
One or two selected from iL yellow and nitrogen oxides
The catalyst for harmful gas purification according to the first or second item of the patent, wherein the desired range is ψ or more.