JPH11179153A - Method and apparatus for cleaning exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply regenerate a deteriorated catalyst with a very small amt. of a halogen compd. in an apparatus wherein CO and hydrocarbons are removed by contact oxidation at low temp. SOLUTION: When an exhaust gas cleaning catalyst is deteriorated, the gas inlet direction of a catalyst layer 2 in a catalytic reactor 12 is shifted by using dampers 3-6. By opening the dampers 3 and 5 provided in an exhaust gas flow path 10a and closing the damper 4 provided in a flow path 10b and the damper 6 provided in a flow path 10c, the exhaust gas flows into from the front side in a figure of the catalytic reactor 12 and by closing the dampers 3 and 5 of the flow path 10b and opening the dampers 4 and 6 of the flow paths 10b and 10c, the exhaust gas flows into from the back side in a figure of the catalytic reactor 12. In addition, when activity of the catalyst is deteriorated, steam may be intermittently poured or the catalyst provided in the outlet part of the exhaust gas in the catalyst layer 2 piled into multistages and the catalyst of the inlet part may be respectively filled again so as to shift them to the gas inlet part and the outlet part or a combustible material such as methanol and propane may be poured into the catalyst layer for a definite period after the catalyst is deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus such as a boiler or an apparatus for purifying exhaust gas discharged from a petrochemical factory, a printing, painting, or cleaning factory, and an operation method thereof. The present invention relates to an exhaust gas purifying apparatus and an operating method capable of efficiently oxidizing and removing combustible substances such as carbon oxides and hydrocarbons.

[0002]

2. Description of the Related Art Exhaust gas containing carbon monoxide (CO) and hydrocarbons is toxic to the human body and at the same time has a strong odor, causing pollution and is desired to be removed with high efficiency. As techniques for removing these, an adsorption method and a catalytic oxidation method are known. However, when the concentration is high, a method using catalytic oxidation is advantageous because the harmful substance removing device becomes compact.

As catalysts used for catalytic oxidation of CO and hydrocarbons, there are known catalysts containing a transition metal oxide as an active component and those carrying a noble metal such as platinum (Pt) or palladium (Pd) on various carriers. In particular, Pt-supported catalysts are widely used because of their high activity and low degradation even at low temperatures.

More specifically, as shown in FIG. 6, a catalyst reactor 12 filled with a catalyst layer 13 is provided in an exhaust gas passage 10 at the outlet of various exhaust gas generating plants 15 and a heating device 1 such as an auxiliary burner is provided.
1 is used to guide the exhaust gas heated to a predetermined temperature to the catalyst layer 13 and oxidize CO and hydrocarbons contained in the exhaust gas into carbon dioxide (CO ₂ ) and water. Generally, a catalyst in which a noble metal (particularly platinum) is supported on alumina or cordierite is used as the catalyst in the catalyst layer 13, and high removal efficiency is obtained at a reaction temperature of 150 to 300 ° C.

[0005]

However, the above prior art does not take into account the deterioration of the catalytic activity when the halogen compound is contained in the exhaust gas, and the catalytic activity decreases sharply in the exhaust gas containing a small amount of the halogen compound. There was a problem of doing. Figure 7 is illustrates an example of a time course of Pt-A1 ₂ O ₃ catalyst activity in exhaust gas containing several ppm hydrogen bromide, the Pt-A1 ₂ O ₃ catalyst when the halogen compound is present in a trace amount Activity drops sharply.

Thousands of ppm of C are contained in exhaust gas discharged from petrochemical plants, printing, painting, and cleaning plants.
In addition to O and hydrocarbons, it usually contains several ppm to several tens ppm of halogen compounds, and exhaust gas purification by the catalytic oxidation method significantly deteriorates the catalyst, requiring a large amount of catalyst to replace the deteriorated catalyst. In addition, the frequency of catalyst replacement is high, and countermeasures have been desired. In particular, the rate of deterioration of the noble metal-supported catalyst due to the halogen compound is more remarkable at lower temperatures, and measures have been taken to extend the use period by using a noble metal catalyst having high low-temperature activity at high temperatures. In addition to the increase in operating cost, the problem of deterioration of the catalyst due to heat is caused.

[0007] In addition, the regeneration treatment of the catalyst, which is performed to reduce the frequency of catalyst replacement, needs to be exposed to a high temperature in the absence of a halogen compound for a long time, during which time the operation of the plant must be stopped.

[0008] An object of the present invention is to provide an exhaust gas purifying apparatus or method capable of operating a halogen compound-containing exhaust gas at a low temperature for a long period of time with high purification efficiency while eliminating the above-mentioned problems of the prior art.

Another object of the present invention is to provide an exhaust gas purifying apparatus or method which can easily regenerate a catalyst deteriorated by a trace amount of a halogen compound in an apparatus for catalytically oxidizing and removing CO and hydrocarbons at a low temperature.

[0010]

The object of the present invention is to solve the above-mentioned problem.
The problem can be solved by delaying the rate of deterioration by the halogen compound with heat or water vapor generated when the catalyst is purified by catalytic oxidation of O or hydrocarbons, or by regenerating the deteriorated catalyst. Specifically, the objects of the present invention can be solved by the following methods and apparatuses for carrying out the invention.

(A) When the exhaust gas purifying catalyst is deteriorated as shown in FIG.
The direction of gas inflow of the catalyst layer 2 in the second 2 is exchanged. That is, by opening the dampers 3 and 5 provided in the main flow passage 10a of the exhaust gas flow passage 10 and closing the damper 4 provided in the bypass flow passage 10b and the damper 6 provided in the bypass flow passage 10c, the exhaust gas is discharged to the catalytic reactor. 12, the exhaust gas flows from the front side in the figure, and the dampers 3, 5 of the main flow path 10a of the exhaust gas flow path 10 are closed, and the dampers 4, 6 of the bypass flow paths 10b, 10c are opened. It flows from behind. (B) When the catalyst activity is deteriorated by the halogen compound, as shown in FIG. 2, the catalyst E or the like which is installed at the exhaust gas outlet of the catalyst layer 2 in which the catalysts A to E are stacked in multiple stages is replaced by the gas inflow. (C) Inject a combustible material such as methanol or propane into the catalyst layer for a certain period after the activity of the exhaust gas purifying catalyst has deteriorated.

(D) During operation of the exhaust gas purifier, a steam injector is provided on the upstream side of the catalyst layer to intermittently add steam to the exhaust gas. (E) When the operation of the exhaust gas purifying device is stopped, water-containing gas (air, N ₂
Flow). (F) The catalyst at the time when the operation of the exhaust gas purification device is stopped is taken out of the device or from the device, and ventilation is performed using steam.

The catalyst used for the catalytic oxidation of CO and hydrocarbons is a catalyst containing a transition metal oxide as an active component or a catalyst supporting a noble metal such as Pt or Pd. Is preferred. In particular, those in which platinum is supported on titania or a honeycomb carrier supporting titania give good results.

In the invention of the above (a) of the present invention, means for changing the flow direction of the exhaust gas into the catalytic reactor 12 includes, as shown in FIG.
a, dampers 3, 5 and bypass passages 10b, 10
The dampers 4 and 6 provided respectively for c may be used,
The flow direction of the exhaust gas may be switched using a plurality of two-way valves (not shown).

In the method (b) in which the catalyst at the exhaust gas outlet and the catalyst at the exhaust gas inlet in the catalyst layer are replaced with each other, the catalyst layer does not need to be multistage, and the exhaust gas inlet and the exhaust gas outlet of the single catalyst layer are replaced. It is also possible to replace and fill by inverting the part.

Further, the combustible used in the invention (c) may be other than methanol, propane or butane, but a substance whose combustion start temperature easily oxidizes and burns at the operating temperature of the exhaust gas purifying apparatus is preferable. In general, oxygen-containing compounds having a small number of carbon atoms, methanol and ethanol, and hydrocarbons having a relatively large number of carbon atoms tend to give good results.

Further, by intermittently injecting steam according to the invention of (d), when the halogen compound is decomposed into hydrogen halide, if steam is present, the steam is disposed on the downstream side of the exhaust gas flow from the catalyst layer. The equipment is significantly corroded,
Since steam is added only when the catalyst has deteriorated, there is no risk of equipment corrosion. Also, only when the catalyst activity has decreased,
Since steam is added, the running cost of steam addition can be reduced.

Further, in the invention of the steam (d), when steam is contained in the exhaust gas in advance, more efficient oxidation purification can be achieved by injecting a shortage of the steam. Furthermore, although the effect can be expected by adding SO ₂ or the like in order to obtain the above effect, water vapor which is very inexpensive and does not affect environmental issues is most suitable.

Further, the inventions of the above (a) to (f)
Each of them may be used alone, or at least two of these methods may be used in combination.
When the invention of (a) or (b) is used, (c)-
A higher effect can be obtained by combining the invention of (f).

[0020]

The present inventors have studied in detail the behavior of the catalyst in the conventional exhaust gas purifying apparatus shown in FIG. 6 in order to prevent the catalyst from deteriorating due to halogen, and have reached the following conclusion.

A) The deterioration of a noble metal catalyst due to a halogen compound is a primary deterioration due to adsorption and is reproducible. B) The adsorption of the halogen compound on the catalyst is extremely weak.
The activity is greatly reduced by raising the temperature to about 0 to 100 ° C., thereby recovering the activity. At this time, the time required for the recovery may be several hours to several tens of hours. C) Deterioration of the catalyst activity by the halogen compound is very large, but when steam is intermittently added, the adsorbed halogen compound is replaced and the activity is recovered. D) The above phenomena A) to C) are particularly remarkable with a Pt-TiO ₂ catalyst.

A feature of the present invention resides in that the above phenomena are used to solve the problems of the prior art. FIG. 3 shows the degradation behavior of a catalyst containing Pt or copper (Cu) as an active component by an accelerated degradation test using hydrogen bromide. As is clear from this figure, the Pt-based catalyst is 50 to 100 ° C. higher than the reaction temperature in the reaction gas compared to the Cu-based catalyst.
Activity can be easily recovered by simply exposing to 50 to 400 ° C for 2 hours. This is because the Pt catalyst has the properties shown in A) and B) above.

Here, if the catalyst gradually degraded by a trace amount of a halogen compound can be intermittently treated at a high temperature for a short period of time by any means, the catalyst activity can be recovered and the high performance can be maintained for a long time. It is possible to continue doing.

On the other hand, the concentration of CO and hydrocarbons in industrial exhaust gas, which must generally be made harmless by catalytic oxidation, is often as high as several thousand ppm. In such a case, the temperature distribution in the catalyst device rises by several tens to 100 ° C. as shown in FIG. 5 due to the heat of the oxidation reaction. Therefore, when the catalyst performance decreases, the catalyst at the exhaust gas inlet having a low temperature and large activity degradation should be located at the exhaust gas outlet by some means, so that the catalyst can be regenerated with the heat of reaction. The methods (a) and (b) employed in the present invention have been achieved based on such an idea, and the operation thereof will be described below.

As shown in FIG. 1, in the invention of FIG.
Exhaust gas is first supplied to the main exhaust gas passage 10 a and the damper 3.
After passing through the catalyst layer 2 to convert CO and hydrocarbons contained in the exhaust gas into CO ₂ and water by catalytic oxidation,
It is discharged through the damper 5. The catalyst in the catalyst layer 2 gradually deteriorates from the exhaust gas inlet due to the halogen compound contained in the exhaust gas, and as a result, the exhaust gas purification performance of the catalyst layer 2 decreases. When the degree of exhaust gas purification performance reaches a certain level, the dampers 3 and 5 are closed, the dampers 4 and 6 are opened, and exhaust gas is introduced from the back side of the catalyst layer 2 through the bypass flow path 10b as shown in FIG. 6, bypass channel 10
When the gas flow direction is changed so as to be discharged from c, the catalyst located at the illustrated exhaust gas inlet portion of the reactor 12 whose activity has been greatly degraded is exposed to the exhaust gas whose temperature has increased due to the heat of reaction, and is regenerated. You.

In the case of the invention (b), the operation in the invention (a) is to be carried out by exchanging the catalyst in one catalyst layer without switching the gas flow path. This is the same as when

On the other hand, when the invention of (c) is used, when the catalyst deteriorates and the exhaust gas purifying device cannot maintain the predetermined performance, the reactivity is higher than that of CO or hydrocarbon to be treated. The gas is injected into the exhaust gas and burned at the exhaust gas inlet of the catalyst layer to perform heating and regeneration.

When several 1000 ppm of highly reactive substances such as methanol and butane are injected into the exhaust gas, they rapidly oxidize at the exhaust gas inlet side of the catalyst layer, and increase the temperature at the exhaust gas inlet of the catalyst layer. With its temperature rise,
The catalyst degraded by halogen is quickly regenerated,
The performance of the exhaust gas purification device is restored. As described above, the time required for regeneration is several hours to several tens of hours, and regeneration can be efficiently performed with a slight increase in fuel cost. In particular, when the calorific value of the gas to be purified is small, it becomes an extremely effective regeneration means.

As described above, the present invention makes it possible to maintain high device performance for a long period of time by skillfully combining the characteristic of deterioration of a noble metal catalyst with a halogen compound and the fact that the gas to be purified often generates heat. It is characterized by the following.

In the invention (d), as shown in FIG.
The steam injection device 7 is provided between the catalytic reactor 12 filled with 3 and the heating device 11, and the steam is introduced into the exhaust gas from the steam injection device 7, whereby the adsorption of halogen to the catalyst is suppressed, and the catalyst is efficiently used at a low temperature. Exhaust gas purification becomes possible. The injection of the steam into the exhaust gas may be on the upstream side of the heating device 11 or may be integrated with the heating device 11 without any problem.

In the prior art shown in FIG. 6, after the exhaust gas discharged from the plant 15 is heated by the heating device 11,
It is sent to the catalyst layer 13. Here, in general, in the presence of water vapor, the activity is reduced due to the inhibition of the adsorption.

Driving using the invention of (d)
As described above, the result of suppressing the adsorption of halogen is derived, and the reduction in the amount of halogen adsorption increases the effective active site of the catalyst, leading to an improvement in the oxidation rate. If a high oxidation rate is obtained, the required amount of catalyst is inevitably reduced, and the cost of operating the apparatus can be reduced.

In general catalytic oxidation, the catalytic activity decreases in the presence of steam. The catalyst of the present invention also reduces the catalytic activity by injecting steam. However, when steam and a halogen compound coexist, the decrease in activity due to water prevents the decrease in activity due to the halogen compound. .

Further, in the method (e), in the present invention, the catalyst regeneration which had to be aged for a long time at a high temperature in the prior art can be smoothly performed at a low temperature.
When the plant is stopped, steam can be injected from the steam injection device 7 shown in FIG. 4 and discharged through the pipe 6 via the pipe 5 and the reactor 12 (catalyst layer 13) to regenerate the catalyst. .

In the method (f), after the operation of the exhaust gas purifying apparatus is stopped, the catalyst layer 13 is taken out from the reactor 12 shown in FIG. 4, and then the catalyst layer 13 is ventilated using steam.

In the regeneration of a catalyst degraded by a halogen compound by using the method (e) or the method (f), water vapor promotes elimination of halogen and can be recovered at a low temperature. In the technology, the fuel which has been heated to a high temperature is not required at the time of regeneration, and the regeneration time can be reduced in a short time, so that a greater cost reduction is possible.

[0037]

Embodiments of the present invention will be described below. Example 1 Titania sol (TiO ₂ ) was applied to a cordierite carrier (cell number: 200 cells / inch, cell thickness: 0.3 mm).
Content 30%), dried at 150 ° C.,
After impregnating again in titania sol and drying at 150 ° C.,
It was baked at 500 ° C. for 2 hours. An aqueous solution of dinitrodiammine platinum was added to the obtained carrier, and Pt was 0.1 wt%
%, And then dried at 150 ° C.
It was calcined at 50 ° C. for 2 hours to obtain an exhaust gas purifying catalyst.

In order to confirm the effect of the regeneration of the catalyst shown in FIG. 1 or FIG.
After the operation for 24 hours, the operation for 24 hours was repeated by reversing the arrangement position of the catalyst at the inlet and the outlet of the exhaust gas of the catalyst layer 10 times.

[0039]

[Table 1]

Comparative Example 1 In order to simulate the prior art, the same catalyst as used in Example 1 was used, and the catalyst layer was held for 480 hours without changing the inlet and outlet of the exhaust gas.

Example 2 A catalyst was prepared in the same manner as in Example 1 except that the titania sol was replaced with alumina sol. Example 1 using this catalyst
A simulation test of catalyst regeneration was conducted in the same manner as in the above.

Comparative Example 2 The same test as in Comparative Example 1 was performed using the catalyst of Example 2.

Example 3 In order to confirm the effect of the above method (c), the catalyst of Example 1 was operated for 480 hours under the conditions shown in Table 1, and then 2,000 ppm of vaporized methanol was injected for 2 hours. The subsequent catalytic activity was investigated.

[0044] Comparative Example 3 Example in place of the catalyst No. Hei 6-320527 of 1 Cu · CeO ₂ · in (JP-A-8-173760) M
A similar test was performed using an n ₂ O ₃ .ZrO ₂ (weight ratio of 1: 1: 4: 4) catalyst.

With respect to the catalysts of Examples 1 to 3 and Comparative Examples 1 to 3, C was initially and after 500 hours.
The results of measuring the O removal rate are summarized in Table 2.

[0046]

[Table 2]

From the comparison between Example 1 and Comparative Example 1 and between Example 2 and Comparative Example 2, in the example of the present invention in which the direction of flow into the catalyst layer is periodically changed, there is almost no decrease in the activity of the catalyst. On the other hand, in the case of the comparative example in which the gas inflow directions were the same, the CO removal performance after 500 hours had been significantly reduced.

As described above, by changing the gas flow direction or changing the catalyst at the exhaust gas inlet and outlet, the catalyst at the exhaust gas inlet of the catalyst layer is used as the exhaust gas outlet, and the catalyst at the exhaust gas outlet is used as the exhaust gas. By operating so as to be at the inlet, deterioration of halogen in exhaust gas due to compounds can be remarkably reduced, and high performance can be maintained for a long time.

In comparison between Comparative Example 1 and Example 3, it was found that in Example 3 according to the present invention in which a highly flammable organic substance was added and the catalyst was heated by the heat of catalytic oxidation, the activity was greatly recovered. doing. This indicates that the method of the present invention, in which an intermittently combustible hydrocarbon is added for operation, is excellent.

Example 4 The catalyst obtained in Example 1 was operated for 700 hours under the conditions shown in Table 3.

[0051] Using the same catalyst as used in Example 4 to simulate the Comparative Example 4 prior art, the H ₂ O = 1.5% in the conditions of Table 3 H ₂ O =
The operation was performed for 700 hours while changing to 0%.

[0052]

[Table 3]

Example 5 A catalyst was prepared in the same manner as in Example 1, except that the titania sol of Example 1 was changed to alumina sol. Example 4 using this catalyst
The same test was performed.

Comparative Example 5 The same test as in Comparative Example 4 was carried out using the catalyst of Example 5.

Example 6 In order to observe the effect of space velocity, the catalyst of Example 4 was used, and the space velocity under the conditions shown in Table 3 was changed to 30,000 h ^-1 to obtain a ^value of 600.
Driving for hours.

Comparative Example 6 A test was conducted by changing the conditions of Example 6 to H ₂ O = 0%.

Example 7 In order to confirm the effects of the methods (d) and (e), a test was conducted using the same catalyst as in Example 1 under the condition of H ₂ O = 0% in Table 3. . However, H ₂ O =
The regeneration operation was performed at 1.5% for 1 hour, and after 700 hours, the activity before regeneration was measured.

COMPARATIVE EXAMPLE 7 The catalyst deteriorated in Comparative Example 5 was ventilated with air at 150 ° C. for 2 hours, and then the activity was measured at a space velocity of 30,000 h ^{−1 in} Table 3.

Example 8 In order to confirm the effect of the method (f), the catalyst degraded in Comparative Example 6 was taken out, immersed in water once, and then dried by ventilation with a drier under the conditions shown in Table 3. Activity was measured.

Comparative Example 8 Using the catalyst used in Comparative Example 7, only ventilation was performed with a drier, and the activity was measured under the conditions shown in Table 3.

Example 9 The same test as in Example 7 was performed using the catalyst used in Comparative Example 8.

Table 4 summarizes the results of measuring the CO removal rates of the catalysts of Examples 4 to 9 and Comparative Examples 4 to 8 both at the initial stage and after the durability test.

[0063]

[Table 4]

From the comparison between Examples 4 to 6 and Comparative Examples 4 to 6, the initial activity was higher in the condition without water vapor, whereas the initial activity was higher in the endurance test for 600 or 700 hours. It can be said that the adsorption of water vapor suppresses the adsorption of halogen, which greatly reduces the activity, due to competitive adsorption on the catalyst surface.

From the comparison between Example 7 and Comparative Example 7,
It can be seen that while little effect was seen when regenerating with low-temperature air, the effect when regenerating with steam was very large. Although this comparison alone is considered to be simply due to the difference in the catalyst components, Example 9 shows Comparative Example 7
Thus, the effectiveness of the regeneration with steam is also recognized from the fact that the catalyst whose activity recovery was small was largely recovered. Further, a similar effect was able to be recognized in the comparison between Example 8 and Comparative Example 8.

[0066]

According to the present invention, a large amount of a catalyst is required due to the conventional deterioration, and CO and hydrocarbons in the exhaust gas containing a halogen compound, for which high performance has not been obtained, can be removed at a low temperature and a high efficiency. It becomes possible to purify.

In the regeneration of the catalyst, a large-scale operation is not required, and a simple operation such as switching of the flow path, refilling of the catalyst at the time of deterioration, or injection of a small amount of combustible material is sufficient, so that it is economical. There are also great benefits. Also, when steam is used for catalyst regeneration, efficient regeneration can be performed in a short time, and the steam used is inexpensive and has no impact on environmental issues. Yes, it has great economic benefits.

[Brief description of the drawings]

FIG. 1 is a diagram showing a flowchart of an exhaust gas purifying facility according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a case where the arrangement position of an exhaust gas purifying catalyst layer according to an embodiment of the present invention is switched between an exhaust gas inlet portion and an exhaust portion.

FIG. 3 is a graph showing a change in catalytic activity due to a halogen compound-containing exhaust gas.

FIG. 4 is a view showing a flowchart of the exhaust gas purifying facility of the embodiment of the present invention.

FIG. 5 is a diagram showing an example of a temperature distribution in a catalyst layer according to a conventional technique.

FIG. 6 is a diagram showing a conventional catalytic combustion device.

FIG. 7: C in the presence of Pt / Al ₂ O ₃ catalyst in the presence of halogen
It is a figure which shows a time-dependent change of O oxidation rate.

[Explanation of symbols]

 2 Catalyst layer 3-6 Damper 7 Steam injection device 10 Exhaust gas channel 11 Heating device 12 Catalytic reactor 15 Exhaust gas source plant

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naomi Imada 3-36 Takara-cho, Kure City, Hiroshima Prefecture Babcock Hitachi Kure Research Laboratory

Claims (8)

[Claims] An exhaust gas purifying method for purifying carbon monoxide and hydrocarbons in an exhaust gas containing a halogen compound through an exhaust gas purifying catalyst reactor having an exhaust gas purifying catalyst and converting the carbon monoxide and hydrocarbons into carbon dioxide or water by catalytic oxidation. During the exhaust gas purification process or during the stop of the exhaust gas purification process, the catalyst located on the exhaust gas inlet side of the exhaust gas purification catalyst reactor is connected to the exhaust gas outlet side of the exhaust gas purification catalyst reactor and the catalyst located on the exhaust gas outlet side of the exhaust gas purification catalyst reactor. An exhaust gas purifying method comprising intermittently performing an operation of bringing the exhausted catalyst into an exhaust gas inlet side of an exhaust gas purifying catalytic reactor. 2. The exhaust gas purifying method according to claim 1, wherein the direction of exhaust gas flowing into the exhaust gas purifying catalyst is changed by switching an exhaust gas flow path between an inlet side and an outlet side of the exhaust gas purifying reactor. 3. An exhaust gas purifying catalyst in an exhaust gas purifying catalyst reactor comprises a catalyst layer provided in one or more stages, and a change in a gas inflow direction with respect to the catalyst layer is determined by changing the position of the catalyst in the single or multi-stage catalyst layer. 3. The method for purifying exhaust gas according to claim 2, wherein the method is performed by exchanging. 4. An exhaust gas purification method for converting carbon monoxide and hydrocarbons in an exhaust gas containing a halogen compound into carbon dioxide or water by catalytic oxidation in an exhaust gas purification catalyst reactor containing an exhaust gas purification catalyst to purify the exhaust gas. 3. The method for purifying exhaust gas according to claim 1, wherein when the catalytic performance is lowered, a combustible gas is injected and simultaneously oxidized by contact to raise the temperature of the catalytic layer for a certain period. 5. An exhaust gas purification method for converting and purifying carbon monoxide and hydrocarbons in an exhaust gas containing a halogen compound into carbon dioxide or water by catalytic oxidation in an exhaust gas purification catalyst reactor containing an exhaust gas purification catalyst. 3. The method for purifying exhaust gas according to claim 1, wherein steam is intermittently added to the exhaust gas during a certain period during exhaust gas purification or during all periods during exhaust gas purification. 6. An exhaust gas purifying method for purifying carbon monoxide and hydrocarbons in an exhaust gas containing a halogen compound through an exhaust gas purifying catalyst reactor having an exhaust gas purifying catalyst and converting the carbon monoxide and hydrocarbons into carbon dioxide or water by catalytic oxidation. The exhaust gas purifying catalyst characterized in that the exhaust gas purifying catalyst is treated with steam in the exhaust gas purifying catalyst reactor during the stop period of the exhaust gas purifying process or is once taken out of the exhaust gas purifying catalyst reactor and treated with steam. Playback method. 7. An exhaust gas purifying apparatus for purifying carbon monoxide and hydrocarbons in an exhaust gas containing a halogen compound through an exhaust gas purifying catalyst reactor having an exhaust gas purifying catalyst and converting the carbon monoxide and hydrocarbons into carbon dioxide or water by catalytic oxidation. In the case where the exhaust gas inflow and outflow directions to the exhaust gas purifying catalytic reactor having the first exhaust gas passage and the second exhaust gas passage are the first exhaust gas passage as the exhaust gas inlet, and the second exhaust gas passage as the exhaust gas outlet. An exhaust gas purifying apparatus characterized by comprising means for switching between a case where the second exhaust gas passage is an exhaust gas inlet and a case where the first exhaust gas passage is an exhaust gas outlet. 8. Exhaust gas purified by converting carbon monoxide and flammable hydrocarbons in an exhaust gas containing a halogen compound through an exhaust gas purifying catalyst reactor containing an exhaust gas purifying catalyst and converting it into carbon dioxide or water by catalytic oxidation. An exhaust gas purifying apparatus, comprising: an injection means for injecting steam or a flammable gas into an exhaust gas channel on the upstream side of an exhaust gas purifying catalytic reactor.