JP2001219078A - Method for catalyst regeneration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently regenerate a catalyst, which is contaminated by a poisonous material in exhaust gas and the activity of which is deteriorated, without causing physical damage such as the sintering of a catalytic component. SOLUTION: The catalyst, which is contaminated by the poisonous material in exhaust gas and the activity of which is deteriorated, is regenerated by heating in the presence of a regenerating gas at 350-450 deg.C in a circulation system or at 400-500 deg.C in a non-circulation system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for regenerating a catalyst. More specifically, the present invention relates to a method for regenerating a catalyst that has been poisoned by a poisoning substance contained in exhaust gas and has deteriorated in activity.

[0002]

2. Description of the Related Art In general, combustion exhaust gas from a garbage incinerator or the like is dust-removed by a dust removing device such as an electric dust collector, a bag filter, a ceramic filter, and the like, and then nitrogen oxides and / or dioxins contained in the exhaust gas. Exhaust gas treatment using a catalyst is performed on harmful substances such as organic halogen compounds in a relatively low temperature range of about 150 to 350 ° C. As such a catalyst, a catalyst containing a titanium oxide and / or a silicon oxide and an oxide of at least one metal selected from the group consisting of vanadium, tungsten and molybdenum is preferably used.

[0003] Combustion exhaust gas from a garbage incinerator includes ammonia gas, sulfur compounds such as sulfur dioxide, sulfur trioxide and ammonium acid sulfate, alkali metal compounds such as potassium and sodium, and alkaline earth compounds such as calcium and magnesium. Poisonous substances such as metal compounds such as mercury, phosphorus, arsenic, lead and antimony are contained in a small amount.
When the above catalyst is used at a relatively low temperature of about 350 ° C., vanadium pentoxide is converted into a sulfate, particularly by a sulfur compound, and acidic ammonium sulfate or ammonium sulfate is accumulated on the surface of the catalyst, thereby closing the pores of the catalyst. As a result, the performance deteriorates with time.

[0004] As a method for regenerating a catalyst which has been poisoned and degraded in activity by poisoning substances contained in exhaust gas, (1) a method of washing and regenerating the catalyst with water or water containing an additive, (2) A method of removing a catalyst from an apparatus and regenerating at a high temperature in a heating furnace is known. However, each of these reproducing methods has the following problems.
The washing and regenerating method (1) has disadvantages in that the regenerating efficiency is low in addition to the outflow of the catalyst component due to water and additives and the difficulty in treating wastewater. In the method (2) of regenerating at a high temperature in a heating furnace, if the temperature is too low, the regeneration efficiency is reduced, and if the temperature is too high, sintering of the catalyst components and even removal of sulfur contained in the catalyst composition are removed. And suffers physical damage.

When harmful substances such as nitrogen oxides and / or organic halogen compounds such as dioxins in waste incinerators and the like are again subjected to exhaust gas treatment using a catalyst having a low regeneration efficiency, the activity is reduced to a certain extent in a short time. Deteriorates, which is not preferable.

[0006]

SUMMARY OF THE INVENTION The present invention relates to (2) a method for regenerating at a high temperature in a heating furnace according to the prior art.
It is another object of the present invention to efficiently regenerate a catalyst that has been poisoned by a poisoning substance in exhaust gas and has deteriorated in activity without causing physical damage such as sintering of a catalyst component by further improvement.

[0007]

In order to solve the above-mentioned problems, the present inventors regenerate the temperature of a catalyst poisoned by a poisoning substance, particularly a sulfur compound, in an exhaust gas and degraded in activity. Various conditions such as the flow rate of the regeneration gas with respect to the weight of the catalyst, the composition of the regeneration gas used for the catalyst to be regenerated, and the like were studied. As a result, it has been found that it is particularly important to set the temperature during reproduction to an optimum range among them, and the present invention has been completed. Furthermore, by selecting optimal conditions for the flow rate of the regeneration gas and the composition of the regeneration gas with respect to the weight of the catalyst to be regenerated, physical damage such as sintering of the catalyst component does not occur, and the efficiency is improved.
It has been found that the catalyst can be regenerated economically.

That is, the catalyst regeneration method of the present invention is a method for regenerating a catalyst that has been poisoned by a poisoning substance in exhaust gas and has degraded its activity.
It is characterized by heating at 0 ° C. and at 400 to 500 ° C. in the non-flow system in the presence of a regeneration gas.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the catalyst regeneration method of the present invention, the heating temperature is important. 350-450 in distribution system
° C, preferably from 370 to 420 ° C. In a non-flow system, the temperature is 400 to 500 ° C, preferably 430 to 480 ° C. When the heating temperature is lower than the above range, the regeneration efficiency is low, and when the heating temperature is higher than the above range, even the sulfur content contained as the catalyst composition is removed, and the recovery of the performance is unfavorably deteriorated. In addition, the cost is also high economically, which is not preferable. In particular, in the case of non-distribution reproduction, physical damage is likely to occur.

It is important that the flow rate of the regenerating gas per 1 kg of the regenerated catalyst is adjusted to a range of 0.5 to ³⁰ m ³ / h (Normal), preferably 1.0 to 20 m ³ / h.
(Normal). When the flow rate of the regeneration gas is lower than the above range, the regeneration efficiency is low, and when the flow rate of the regeneration gas is higher than the above range, even the sulfur content contained as the catalyst composition is removed, and the performance recovery is deteriorated. Not preferred. In addition, the pressure loss in the catalyst increases, and a high-capacity intake blower and exhaust blower are required, and energy consumption increases, which is not preferable. As the composition of the regeneration gas, O ₂ is preferably 5% by volume or more, more preferably 7% by volume or more and 21% by volume or less, H ₂ O is preferably 40% by volume or less, and sulfur oxide is preferably 5000% by volume or less. It is more preferable that the content is 3000 volume ppm or less, NH ₃ is preferably 5000 volume ppm or less, more preferably 3000 volume ppm or less, and dust is preferably 0.1 g / m ³ (Normal) or less. Outside these ranges, the regeneration efficiency will be low. In particular, when the dust is more than 0.1 g / m ³ (Normal),
The performance of the catalyst also deteriorates due to the dust component, and the regeneration efficiency decreases. When performing regeneration in a non-flow system, sulfur compounds attached to the catalyst are decomposed, and ammonia gas and sulfur oxides such as sulfur dioxide and sulfur trioxide are generated. Is exhausted, outside air is taken into the system, and the gas composition is adjusted to the above-mentioned gas composition.

In the present invention, the term "flow system" refers to a case where a gas is forcibly passed directly through a catalyst such as a reactor. on the other hand,
The non-flow system refers to a case where the gas is not forced to flow directly through the catalyst. Typical examples of the non-flow system include a circulation furnace and a muffle furnace. The flow rate of the regeneration gas in the non-flow system refers to the amount of circulating gas in the case of a circulating furnace, and refers to the flow rate of an intake blower or an exhaust blower in the case of a muffle furnace. When performing regeneration in a distribution system, a regeneration system may be incorporated in the local incineration facility, or regenerated into existing equipment with high-temperature exhaust gas (for example, exhaust gas from power generation equipment, boiler exhaust gas, incinerator exhaust gas, firing furnace exhaust gas, etc.). An apparatus may be installed. When the catalyst is degraded in activity by the poisoning substance, regeneration is performed by introducing these exhaust gases. As an advantage of performing regeneration in a circulation system, the cost required for heating can be reduced because the heat source can be used effectively.

In the case of performing regeneration in a non-flow system, an apparatus such as a circulation furnace or a muffle furnace generally used for calcining a catalyst may be used. When regeneration is performed in a non-distribution system, the heating temperature for regeneration is higher and the time required for regeneration is longer than when regeneration is performed in a distribution system, but existing equipment can be used and no new capital investment is required It has the advantage of being
The catalyst to be regenerated according to the present invention is not particularly limited, as long as it is poisoned by the poisoning substance in the exhaust gas, particularly a catalyst that has been degraded in activity by poisoning, for example, nitrogen oxides and / or organic halogen compounds. Catalysts used in the treatment of exhaust gases containing (such as dioxins) are preferred. In particular, when the catalyst is used at a relatively low temperature, the performance is significantly deteriorated with time, so that the dust collector is disposed downstream of an electric dust collector, a bag filter, a ceramic filter, or the like of a garbage incinerator, preferably a ceramic filter. And / or downstream of the bag filter at a temperature of 3
Catalysts used at temperatures below 50 ° C., preferably between 150 and 300 ° C., for the treatment of exhaust gases containing nitrogen oxides and / or organic halogen compounds are suitable.

The composition of the catalyst to be regenerated according to the present invention may be any composition suitable for the intended exhaust gas treatment. For example, if the catalyst is used for treating exhaust gas containing nitrogen oxides and / or organic halogen compounds, titanium oxide and / or silicon oxide, vanadium,
It is preferable to contain an oxide of at least one metal selected from the group consisting of tungsten and molybdenum. Powder may be used as the shape of the catalyst to be regenerated according to the present invention. In addition, a plate-like, corrugated plate-like, mesh-like, honeycomb-like, cylindrical, cylindrical, or other integrally formed body may be used, or a plate-like or corrugated plate made of alumina, silica, cordierite, titania, stainless metal, or the like. It may be used by being supported on a carrier having a shape such as a net, a honeycomb, a column, or a cylinder.

[0014]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Reference Example 1 A new catalyst (1) before being exposed to exhaust gas is referred to as Reference Example 1. This new catalyst (1) contains 70% by weight of titanium oxide, 9.5% by weight of silicon oxide, 10% by weight of vanadium oxide, 10% by weight of molybdenum oxide, and 0.5% by weight of sulfur content. It is a honeycomb-shaped catalyst contained.

Reference Example 2 A new catalyst (2) before being exposed to exhaust gas is referred to as Reference Example 2. This new catalyst (2)
A powdery catalyst containing 70% by weight of titanium oxide, 9.5% by weight of silicon oxide, 10% by weight of vanadium oxide, 10% by weight of tungsten oxide and 0.5% by weight of sulfur. is there. [Comparative Example 1] The new catalyst (1) of Reference Example 1 was placed downstream of a bag filter of a garbage incinerator at a temperature of 200 ° C and 20 ppm by volume of sulfur oxides, 80 ppm by volume of NH ₃ , and nitrogen oxides. 100 ppm by volume, 2 ng-TE of dioxins
Q / m ³ (Normal), O ₂ 10% by volume, H ₂ O 15
It was used for treating exhaust gas containing volume%. The catalyst (1) which was poisoned by the poisoning substance by this exhaust gas exposure and degraded in activity was designated as Comparative Example 1.

Comparative Example 2 New Catalyst of Reference Example 2 (2)
At a temperature of 200 ° C downstream of the bag filter of the garbage incinerator.
20 ppm by volume of sulfur oxide and 80 volumes by volume of NH ₃
pm, 100 ppm by volume of nitrogen oxide, 2 ng-TEQ / m ³ (Normal) of dioxins, 10% by volume of O ₂ , and 15% by volume of H ₂ O for treating exhaust gas. The catalyst (2) which was poisoned by the poisoning substance by this exhaust gas exposure and degraded in activity was designated as Comparative Example 2. [Examples 1 and 2] 1 kg of the catalyst (1) which was poisoned by the poisoning substance and was degraded in activity by the exhaust gas exposure of Comparative Example 1
Under a condition of a flow rate of a regeneration gas of 3.5 m ³ / h (Normal), a heat treatment regeneration was carried out for 10 hours in a flow system at a temperature of 350 to 450 ° C. The composition of the regeneration gas is such that the oxygen concentration is 5% by volume, the sulfur oxide and NH ₃ concentrations are 3000 ppm by volume or less, the H ₂ O concentration is 5% by volume or less, and the dust concentration is 0 g / m ³ (Normal). The temperature was 350 ° C. in Example 1 and 450 ° C. in Example 2.

Examples 3 to 5 Exposure to exhaust gas of Comparative Example 1
Degraded by poisoning by poisonous substances (1)
And the flow rate of the regeneration gas per kg of the catalyst is 3.5 m^Three/
h (Normal), the temperature range is 400-500 ° C.
, A heat treatment regeneration was performed for 20 hours in a non-flow system. What
The composition of the regeneration gas is as follows: oxygen concentration is 5% by volume, sulfur oxidation
And NH_ThreeThe concentration is 3000 ppm by volume or less, H_TwoO concentration
Degree is 5% by volume or less, dust concentration is 0g / m ^Three(Normal)
And the temperature was as follows: Example 3: 400 ° C., Example 4: 45
0 ° C., Example 5: 500 ° C.

[Examples 6 and 7] Catalyst (1) which was poisoned by the poisoning substance by exposure to exhaust gas of Comparative Example 1 and degraded in activity
And the flow rate of the regeneration gas per kg of the catalyst is 3.5 m ³ /
h (Normal), temperature of 350 ° C, oxygen concentration 3
The heat treatment was regenerated for 10 hours in a flow system in the range of 〜7% by volume. Note that the composition of the regeneration gas is sulfur oxide and N
The H ₃ concentration is 3000 vol ppm or less, the H ₂ O concentration is 5 vol% or less, the dust concentration is 0 g / m ³ (Normal),
Example 6: 3% by volume, Example 7: 7% by volume
And [Examples 8 to 9] 1 kg of the catalyst (1) which was poisoned by the poisoning substance and was deteriorated in activity by the exhaust gas exposure of Comparative Example 1
The flow rate of regeneration gas per unit is 3.5 m ³ / h (Normal),
At a temperature of 450 ° C., the heat treatment was regenerated for 20 hours in a non-flow system at an oxygen concentration of 3 to 7% by volume. The composition of the regeneration gas is such that the sulfur oxide and NH ₃ concentration are 3
000 ppm by volume or less, H ₂ O concentration is 5% by volume or less, dust concentration is 0 g / m ³ (Normal), and oxygen concentration is
Example 8: 3% by volume, Example 9: 7% by volume.

[Examples 10 to 11] The catalyst (1), which was poisoned by the poisoning substance and exposed to degradation in the exhaust gas exposure of Comparative Example 1, was converted into a regenerated gas per kg of the catalyst at a temperature of 350 ° C. Flow rate of 0.5 to 37.5 m ³ / h (Norma
Within the range of l), the heat treatment was regenerated for 10 hours in a flow system. The composition of the regeneration gas is such that the oxygen concentration is 5% by volume, the sulfur oxide and NH ₃ concentrations are 3000 ppm by volume or less,
_{The 2} O concentration is 5% by volume or less, and the dust concentration is 0 g / m ³ (Nor
mal), and the flow rate of regeneration gas per kg of catalyst is
Example 10: 0.5 m ³ / h (Normal), Example 11:
It was 37.5 m ³ / h (Normal).

Example 12 The catalyst (1) which was poisoned by the poisoning substance by the exposure to the exhaust gas of Comparative Example 1 and had its activity degraded was
The flow rate of the regeneration gas per 1 kg of the catalyst is 3.5 m ³ / h
(Normal), the heat treatment was regenerated for 10 hours in a flow system under the condition of a temperature of 350 ° C. The composition of the regeneration gas was such that the oxygen concentration was 5% by volume, the sulfur oxide and NH ₃ concentrations were 5000 ppm by volume or less, the H ₂ O concentration was 5% by volume or less, and the dust concentration was 0 g / m ³ (Normal). Was. [Example 13] The catalyst (1) which was poisoned by the poisoning substance by the exposure to the exhaust gas of Comparative Example 1 and degraded in activity, the flow rate of the regeneration gas per kg of the catalyst was 3.5 m ³ / h (Normal), and the temperature was Was subjected to heat treatment regeneration for 20 hours in a non-flow system at 450 ° C. The composition of the regeneration gas was such that the oxygen concentration was 5% by volume, the sulfur oxide and NH ₃ concentrations were 5000 ppm by volume or less, the H ₂ O concentration was 5% by volume or less, and the dust concentration was 0 g / m ³ (Normal). Was.

[Example 14] The catalyst (2) which was poisoned by the poisoning substance in the exhaust gas exposure of Comparative Example 2 and degraded in activity,
The flow rate of the regeneration gas per 1 kg of the catalyst is 3.5 m ³ / h
(Normal) The heat treatment and regeneration were performed in a non-flow system at a temperature of 450 ° C. for 20 hours. The composition of the regeneration gas was such that the oxygen concentration was 5% by volume, the sulfur oxide and NH ₃ concentrations were 3000 ppm by volume or less, the H ₂ O concentration was 5% by volume or less, and the dust concentration was 0 g / m ³ (Normal). Was. [Comparative Examples 3 and 4] 1 kg of the catalyst (1), which was poisoned by the poisoning substance and degraded in activity when exposed to the exhaust gas of Comparative Example 1,
Under a condition of a flow rate of the regeneration gas per unit area of 3.5 m ³ / h (Normal), heat treatment and regeneration were performed at 300 ° C. and 500 ° C. in a flowing system for 10 hours. The composition of the regeneration gas is such that the oxygen concentration is 5% by volume, the sulfur oxide and NH ₃ concentrations are 3000 ppm by volume or less, the H ₂ O concentration is 5% by volume or less, and the dust concentration is 0 g / m ³ (Normal). The temperature was set to 300 ° C. in Comparative Example 3: 500 ° C. in Comparative Example 4.

[Comparative Examples 5 to 6]
Degraded by poisoning by poisonous substances (1)
And the flow rate of the regeneration gas per kg of the catalyst is 3.5 m^Three/
Under the condition of h (Normal), the temperature is 350 ° C. and 550
At 20 ° C., the heat treatment was regenerated for 20 hours in a non-flow system. What
The composition of the regeneration gas is as follows: oxygen concentration is 5% by volume, sulfur oxidation
And NH_ThreeThe concentration is 3000 ppm by volume or less, H_TwoO concentration
Degree is 5% by volume or less, dust concentration is 0g / m ^Three(Normal)
Comparative Example 5: 350 ° C., Comparative Example 6: 55
0 ° C.

Test Example 1 The catalysts subjected to heat treatment and regeneration in Examples 1 to 14, the new catalysts in Reference Examples 1 and 2, and the catalysts whose activity was deteriorated in Comparative Examples 1 and 2, and Comparative Examples 3 to 6 A part of each catalyst of the catalyst subjected to the heat treatment and regeneration was cut out, pulverized and compression molded as an analysis sample, and the sulfur content in each catalyst was quantified by a fluorescent X-ray measuring device. The regeneration efficiency (%) was determined according to the following equation. Table 1 shows the results. Regeneration efficiency (%) = ｛Sulfur content in catalyst before regeneration (% by weight)
-Sulfur content in catalyst after regeneration (% by weight) / {Sulfur content in catalyst after regeneration (% by weight)-Sulfur content in new catalyst (% by weight)} x 100 [Test Example 2] Catalysts subjected to heat treatment regeneration in 1-12, new catalysts of Reference Examples 1-2, and catalysts with degraded activity of Comparative Examples 1-2, and catalysts subjected to heat treatment regeneration in Comparative Examples 3-6 The test was performed under the following reaction conditions to determine the denitration rate. Table 1 shows the results.

—Test Conditions— Space velocity 11,300 h ⁻¹ Gas linear velocity 2.79 m / s (Normal) Gas temperature 200 ° C. NH ₃ / NO molar ratio 1.0 Gas composition NO 200 vol ppm (Dry) SO ₂ 50 vol ppm (Dry) _{) O 2 10vol% (Dry)} H 2 O 15vol% N 2 balance gas test example 3 catalyst was heat-treated reproduced by examples 1 to 14, fresh catalyst of example 1-2, and Comparative examples 1 to For each of the two catalysts of which the activity was deteriorated and the catalysts which were subjected to heat treatment and regeneration in Comparative Examples 3 to 6, using chlorotoluene as an alternative substance to confirm the decomposition performance of dioxins,
Tests were performed under the following reaction conditions to determine the chlorotoluene decomposition rate. Table 1 shows the results.

—Test Conditions— Space velocity 2,710 h ⁻¹ Gas linear velocity 0.5 m / s (Normal) Gas temperature 200 ° C. Gas composition Chlorotoluene 30 vol ppm (Dry) O ₂ 10 vol% (Dry) H ₂ O 15 vol% N ₂ Balance gas [Test Example 4] The catalysts subjected to heat treatment and regeneration in Example 3 and Comparative Example 5 were subjected to a gas temperature of 200 ° C., an O ₂ concentration of 10% by volume, an H ₂ O concentration of 15% by volume, respectively. Exposure was performed under exhaust gas conditions in which the sulfur oxide and NH ₃ concentrations were 500 ppm by volume. The catalyst after the exposure was tested under the reaction conditions shown in Test Example 2 to determine the denitration rate. Table 2 shows the results.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

According to the present invention, the catalyst can be efficiently and economically regenerated without causing physical damage such as sintering of the catalyst component.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Nobuyuki Masaki 992, Nishioki, Okihama-shi, Abashiri-ku, Himeji-shi, Hyogo Nippon Shokubai Co., Ltd. F-term in Nippon Shokubai (reference) 4D048 AA06 AA11 BA06X BA07X BA23X BA26X BA27X BA41X BB01 BB02 BB03 BB05 BB07 BD01 BD02 CC39 CD05 4G069 AA10 BB04A BB04B BC50A BC50B BC54A BC54B BC59A01 CA60 EA01 GA02

Claims (6)

[Claims] 1. A method for regenerating a catalyst which has been poisoned by a poisoning substance in an exhaust gas and has degraded its activity, comprising 35
A method for regenerating a catalyst, comprising heating at 0 to 450 ° C in the presence of a regeneration gas. 2. A method for regenerating a catalyst which has been poisoned by a poisoning substance in an exhaust gas and has degraded its activity.
A method for regenerating a catalyst, comprising heating at 00 to 500 ° C in the presence of a regeneration gas. 3. A flow rate of the regeneration gas per 1 kg of the regenerated catalyst is in a range of 0.5 to ³⁰ m ³ / h (Normal).
A method for regenerating a catalyst according to claim 1 or 2. 4. The composition of the regeneration gas, wherein (1) O ₂
5% by volume or more, (2) 40% by volume or less of H ₂ O, (3) 5000 ppm by volume or less of sulfur oxide, and (4) 50% by volume of NH ₃
00 ppm by volume or less, and (5) 0.1 g /
4. The method for regenerating a catalyst according to claim 1, wherein at least one of the following conditions is satisfied: m ³ (Normal). 5. The catalyst to be regenerated is titanium oxide and / or
The method for regenerating a catalyst according to any one of claims 1 to 4, further comprising a silicon oxide and an oxide of at least one metal selected from the group consisting of vanadium, tungsten, and molybdenum. 6. The catalyst to be regenerated is a catalyst that is used in the treatment of exhaust gas containing nitrogen oxides and / or organic halogen compounds at a temperature of 350 ° C. or lower in the downstream of a dust remover of a refuse incinerator. Item 6. A method for regenerating a catalyst according to any one of Items 1 to 5.