JPH04293543A - Deodorizing and deoxygenating catalyst - Google Patents

Abstract

PURPOSE:To remove the malodor and oxygen in gas containing a malodorous component, reducible gas and residual oxygen. CONSTITUTION:An oxide solid catalyst contains 70-90wt.% of manganese dioxide (MnO2) and 10-30wt.% of cuppric oxide (CuO) as catalytically active components. By reacting gas containing a malodorous component, reducible gas and residual oxygen with the catalyst, the malodorous component is decomposed by oxidation to be deodorized and residual oxygen is used for the oxidation of the malodorous component and removed by the reaction with the reducible gas component contained in other raw material gas.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to deodorizing and deoxidizing catalysts.

More specifically, gas containing malodorous components, reducing gases, and low concentrations of residual oxygen (hereinafter referred to as raw material gas) produced as by-products or synthesized in various industries is processed using the pressure swing method (PSA method). When attempting to recover, separate, and/or purify using cryogenic separation method, membrane separation method using hollow fiber gas separation membrane, etc., it is used to prevent bad odor of purge gas discharged from such equipment, and to remove raw material gas. This invention relates to a catalyst for removing residual oxygen, which is a problem when attempting to recover, separate, and/or purify it.

0003

BACKGROUND OF THE INVENTION In recent years, bad odor pollution has been widely taken up as a social issue, and as a result, there has been an increasing need for treatment of exhaust gas containing malodorous components, that is, deodorization.

From this point of view, there have been many methods used singly or in combination, such as the catalytic oxidation method using conventional catalysts, the gas cleaning method, the ozone oxidation method, the adsorption method, the chemical deodorizing agent, the masking method, and the gas combustion method. It has been proposed and is widely used industrially.

[0005] However, each has its advantages and disadvantages,
Industrially, this method was not completely satisfactory due to many problems such as running costs and equipment maintenance.

[0006] In addition, various studies have been conducted regarding these methods because it is suitable to deodorize the raw material gas, but they are not yet fully satisfactory, and countermeasures using purge gas, which is exhaust gas, are still the mainstream. However, the purge gas was simply deodorized.

For example, in the catalytic oxidation method using a catalyst, it is a simple deodorizing device, and since a catalyst is used, there is generally no need for post-treatment or regeneration, so it is a preferable method, but it is still not fully satisfactory. It's not a thing. Those that are effective only against specific and limited malodorous components, or require pretreatment such as removing moisture from the raw material gas containing malodorous components, or require high reaction temperatures during contact reaction with catalysts. There were also problems in selecting the optimal catalyst, life, etc., and it was desired to search for, research, and develop a catalyst that can be used sufficiently without being limited to the conditions of malodorous components. .

[0008] Furthermore, the gas cleaning method is not preferable because its ability to remove low-concentration malodorous substances is insufficient, and because it uses chemicals, it is necessary to treat the washed waste liquid.

[0009] The ozone oxidation method focuses on the strong oxidizing power of ozone, but the equipment is large and it is difficult to adjust the amount of ozone added according to changes in odor concentration.
The equipment and running costs are also high, making it economically disadvantageous.

[0010] Adsorption methods and chemical deodorizing agents have a low ability to remove malodorous substances at low concentrations, and there are problems during regeneration such as treatment of adsorbents and deodorizing agents.

[0011] The masking method is not suitable from the viewpoint of deodorization and cannot be widely applied.

The gas combustion method requires a combustion device, which is economically disadvantageous.

[0013] Furthermore, the above-mentioned combination method requires a complicated apparatus and is economically unfavorable in terms of initial investment and running costs.

For example, the ozone oxidation method and the catalytic oxidation method using a catalyst are widely researched or developed industrially, but the steps are complicated and uneconomical, and further improvements are desired.

On the other hand, regarding the residual oxygen in the raw material gas,
When attempting to recover, separate, and/or purify gases composed of various components generated in various industries using the aforementioned pressure swing method, cryogenic separation method, membrane separation method, etc.,
Particularly when considering the purity of the gas to be obtained, it is important to remove residual oxygen from the raw material gases, and there is a need for methods, devices, etc. that can remove oxygen with simple operations.

It is generally said that impurities remaining in the raw material gas can be easily removed using adsorbents, chemical treatments, or other methods, but residual oxygen cannot be easily removed. After separating the target gas, in order to further increase its purity, the oxygen content is removed by oxidative combustion using a catalyst along with excess hydrogen, which requires additional removal equipment, etc. It's still not an economical method.

[0017]

[Problems to be Solved by the Invention] The present invention provides industrially simplified deodorization of raw material gas containing malodorous components.
The present invention provides a deodorizing catalyst with low initial investment and running costs, and at the same time provides a catalyst that removes residual oxygen contained in the raw material gas.

[0018]

[Means for Solving the Problems] As a result of intensive studies in view of the above problems, the present inventors have devised a solution for by-product gas containing malodorous components, reducing gases, and low concentrations of residual oxygen, or in synthetic gas. The malodorous components are oxidized and decomposed with a portion of the residual oxygen to make them odorless, and the residual oxygen is reacted with the malodorous components used to oxidize the malodorous components and/or other reducing gas components contained in the raw material gas to form oxides. They discovered a catalyst that can be removed by this method and completed the present invention.

In the present invention, the raw material gas containing malodorous components and residual oxygen is simply subjected to a catalytic reaction using a catalyst, and the raw material gas is recovered, separated and/or purified, and the target gas is obtained. Easily and efficiently obtains a deodorizing effect without deodorizing the emitted purge gas, and at the same time removes residual oxygen, which is a problem when producing high-purity gas, to a state that contains virtually no oxygen. The purpose of this invention is to provide a catalyst that increases the

That is, the present invention uses manganese dioxide (MnO ) 70 to 90% by weight and cupric oxide (CuO 2 ) 10 to 30% by weight.

Further, the present invention will be explained in detail.

The active ingredients MnO2 and CuO used in the present invention are not particularly required to have high purity, and it is sufficient to use commercially available products.

The oxide solid catalyst of the present invention is used by adding, preferably, a binder to these active ingredients, mixing and molding.

The binders used include inorganic binders such as water glass, colloidal silica, bentonite talc, and boehmite gel (AlOOH), as well as dextrin, wax, starch, carboxymethylcellulose, methylcellulose, crystalline cellulose, and polyester. Examples include organic binders such as vinyl acetate and polyvinyl alcohol.

The amount of binder added is about 2 to 20% by weight based on the active ingredients; less than 2% by weight is not preferable because the strength of the catalyst is insufficient, and conversely, if it exceeds 20% by weight, the catalyst This is not preferable because the performance of

The main composition of the MnO2 and CuO based oxide solid catalyst of the present invention is as follows:
2: 70 to 90% by weight; CuO: 10 to 30% by weight. Particularly preferably, MnO
2; 77.5-82.5% by weight, CuO; 22.5-82.5% by weight
It is in the range of 17.5% by weight.

[0027] MnO2 is less than 70% by weight and/or C
If uO is less than 10% by weight, the content of active components will be reduced and the oxidizing action as a catalyst will be insufficient, which is undesirable.On the other hand, if MnO2 exceeds 90% by weight and/or CuO exceeds 30% by weight, This is not preferable, since there is a tendency for the deodorizing effect to decrease, perhaps due to a decrease in the effectiveness as a catalyst.

[0028] These active components suitably range from 80 to 97% by weight of the total catalyst in the form of oxides, and other components include alumina, silica, bentonite, zirconia, magnesia, titania, graphite, activated carbon,
In addition, any other material may be used as long as it does not adversely affect the active components of the catalyst, which is mainly composed of MnO2 and CuO2.

It is generally known that the catalytic oxidation method using a catalyst is easily affected by moisture in the raw material gas to be treated.
It has been confirmed that the oxide solid catalyst of the present invention is hardly affected by moisture.

According to the knowledge of the present inventors, it has been confirmed that the relative humidity is not affected by the catalyst if it is within 200%, preferably within 150%.

Furthermore, the specific surface area of the oxide solid catalyst in the present invention is at least 150 to 400 m2/g.
It is preferably about 200, more preferably about 200
~300 m2/g is suitable. Note that the specific surface area is measured by the BET method.

The shape of the oxide solid catalyst in the present invention is not particularly limited, and may be granular, spherical, pellet, tablet, honeycomb, or rod-like.

The reaction conditions using the catalyst include heating or cooling the raw material gas directly or indirectly;
Preferably 0 to 350°C, more preferably 10 to 2
Contact with catalyst within 50°C. If the contact temperature with the catalyst is less than 0°C, sufficient deodorization and deoxidation will not be achieved, and if it exceeds 350°C, it will adversely affect the material of the equipment, the life of the catalyst, etc., which is undesirable.

In this way, the malodorous components in the raw material gas are
The catalyst reacts with a portion of the low concentration of residual oxygen to form, for example, carbon dioxide, water, and other oxides. Further, the residual oxygen that does not contribute to the reaction with the malodorous component reacts with the reducing gas component in the raw material gas and similarly becomes an oxide.

[0035] The reducing gas component may be, for example, hydrogen, carbon monoxide, or the like, and is not particularly limited.

In the present invention, the raw material gas containing malodorous components and residual oxygen is not particularly limited, but includes, for example, the general chemical industry, the petrochemical industry including petroleum refining, the steel industry,
Synthetic and/or by-product gases produced from metal smelting, ceramics, gas businesses, and others can be suitably used.

Further, the residual oxygen concentration in the raw material gas is industrially preferably 5% by volume or less, more preferably 1% by volume or less, considering the catalyst device to be installed. Of course, a malodorous component and/or a reducing gas component commensurate with the oxygen content is required in the raw material gas, but if the reducing gas component is insufficient, it may be added separately, or vice versa. If oxygen is insufficient, oxygen or air may be supplied separately, but it goes without saying that conditions rich in reducing gas are preferable.

The malodorous substances referred to in the present invention include hydrogen sulfide, methyl sulfide, methyl mercaptan, ethylamine, methylamine, trimethylamine, dimethylamine, methyl disulfide, diethylamine, triethylamine, isobutylamine, acetone, pyridine, methyl ethyl ketone, acetaldehyde, Formaldehyde, benzene, xylene, toluene, phenol, acrolein, acetylene, acetic acid, butyric acid, etc., and other substances that can oxidize chain organic compounds, cyclic organic compounds, etc. can be mentioned. These substances can be decomposed and removed by the catalyst of the invention, but are not limited to these substances.

In the reaction with the oxide solid catalyst in the present invention, the space velocity (SV) varies depending on the concentration and composition of the gas components, the type of gas, etc., but is between 1000 and 20.
0000 h-1 is preferable.

The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a flow diagram illustrating a preferred embodiment of the present invention.

In FIG. 1, the raw material gas is supplied to the raw material gas inlet 1.
If necessary, use a heat exchanger etc. to maintain the temperature between 0 and 350℃.
temperature. Next, the gas is introduced into a reaction tower 3 filled with the oxide solid catalyst 2 according to the present invention, subjected to catalytic oxidation to remove malodorous components and residual oxygen, and sent to a subsequent process through a treated gas outlet 5.

[0042] The control conditions are determined by taking into consideration the concentration of the raw material gas, the amount of processing, the malodor components of the processing gas, the concentration of oxygen, etc.
It may be selected as appropriate, and by monitoring the oxygen concentration of the processing gas using the trace oxygen analyzer 4, the degree of removal of malodorous components and residual oxygen can be easily determined.

Furthermore, in order to enhance the deodorizing effect or to efficiently remove residual oxygen, pretreatments such as washing the raw material gas with water, washing with acid or alkali, and adsorption with activated carbon are also suitable.

[0044]

[Examples] The present invention will be explained in detail below with reference to Examples. VOL% represents capacity %.

Example 1 Mn02 and CuO were each pulverized using an impact pulverizer, and then pulverized using a ball mill to a size of 100 mesh or less. Crushed product Mn02 (800kg) and CuO
(200 kg) and bentonite (10 kg) as a binder.
After adding an appropriate amount of water and kneading well in a kneader, the mixture was dried for 6 hours in a fluidized dryer at a temperature of 105°C, and after cooling, it was ground to 8 to 16 mesh, with a specific surface area of 207 m2. An oxide solid catalyst having a weight ratio of 1/g was obtained.

The catalyst prepared above was charged into the catalytic oxidation apparatus shown in FIG. 1, and hydrogen sulfide, a typical malodorous component,
Raw material gas by-produced from a steam reformer containing 30 ppm (average concentration 15 ppm) (temperature 150 °C) 1
The test was carried out at 800 m3/h according to the flow sheet shown in FIG. The catalyst filling amount was 100 liters, and the test was conducted continuously for 1000 hours under the above conditions, and the hydrogen sulfide concentration and deodorization rate of the treated raw material gas were measured every 200 hours. Note that the space velocity was 18,000 h-1.

Table 1 shows the analysis results of the raw material gas composition. Note that the raw material gas is analyzed by gas chromatography-mass spectrometry (GC-MS method). Further, Table 2 shows the hydrogen sulfide concentration and deodorization rate of the treated raw material gas every 200 hours, and Table 3 shows the analysis results of the catalyst used.

[0048]

[Table 1]

[0049]

[Table 2]

Incidentally, the deodorization rate was determined by the following formula. Deodorization rate (%) = (1 - hydrogen sulfide concentration at the reaction tower outlet/average hydrogen sulfide concentration at the reaction tower inlet) x 100

[0051]

[Table 3]

The oxygen concentration was continuously measured using a trace oxygen analyzer. The oxygen concentration in the gas after treatment is 3 to 5.
It was ppm.

Example 2 Using the same equipment and catalyst as in Example 1, the test was conducted continuously for 1100 hours using the raw material gas produced as a by-product during the production of formaldehyde. The test conditions were: raw material gas amount 6000m3/h;
The catalyst filling amount was 380 liters.

The raw material gas is analyzed by gas chromatography-mass spectrometry (GC) for its main components after removing moisture.
-MS method). The results are shown in Table 4. Also,
Table 5 shows the odor concentration and deodorization rate at the inlet of the catalytic oxidizer and the outlet of the catalytic oxidizer for every 200 hours of elapsed time. Note that the space velocity was 1.6 x 104 h-1.

[0055]

[Table 4]

[0056]

[Table 5]

Incidentally, the deodorization rate was determined by the following formula. Deodorization rate (%) = (1 - Odor concentration at the outlet of the reaction tower / Odor concentration at the inlet of the reaction tower) x 100 In addition, the odor concentration was measured using the three-point comparison described in the 1981 Sensory Test Method Investigation Report (Environment Agency). It was conducted based on the odor bag method.

Concerning oxygen concentration, continuous measurement was carried out using a trace oxygen analyzer. The oxygen concentration in the raw material gas after treatment was 2 to 4 ppm.

[0059]

[Effects of the Invention] In this way, by using the oxide solid catalyst of the present invention, the raw material gas can be deodorized, and the purge gas generated when this gas is recovered, separated, and purified is made odorless. be able to.

[0060] Furthermore, the oxide solid catalyst in the present invention is
By almost completely reacting the residual oxygen content in the raw material gas and creating a raw material gas that does not substantially contain oxygen, when various gases are recovered and purified using the raw material gas as a starting material, new
It does not require an oxygen removal device, and its industrial advantage is great.

Furthermore, deodorization and removal of oxygen components can be carried out with an extremely simple device that only requires a reaction tower filled with the oxide solid catalyst of the present invention during the process, and the industrial and It has great economic significance.

The present invention provides a deodorizing catalyst that is industrially simple and requires low initial investment and running costs when deodorizing raw material gas containing malodorous components, regardless of the composition and concentration of malodorous components. , provides a catalyst that removes residual oxygen contained in the raw material gas.

[Brief explanation of drawings]

FIG. 1 shows an example of a flow sheet of equipment suitable for carrying out the invention.

[Explanation of symbols]

1 Raw material gas inlet 2 Oxide solid catalyst 3 Reaction tower 4 Trace oxygen concentration meter 5 Processing gas outlet 6 Sampling port 7 Sampling port 8 Drain removal

Claims (1)

[Claims] Claim 1: When a gas containing malodorous components, reducing gases, and low concentrations of residual oxygen is deodorized and deoxidized using a catalyst, manganese dioxide (MnO) is used as an active component of the catalyst.
2) 70-90% by weight, and cupric oxide (CuO) 1
An oxide solid catalyst characterized by containing 0 to 30% by weight.