JP2023058313A - Catalyst for production of ammonia, ammonia production method and ammonia production device, and denitration method and denitration device - Google Patents

Abstract

To provide a catalyst that enables the production of ammonia from exhaust in high yield, an ammonia production method and an ammonia production device, and a denitration method and a denitration device.SOLUTION: The present invention relates to a catalyst for the production of ammonia, which produces NH3 from NOX and a reductant in the presence of oxygen, the catalyst comprising a carrier composed of TiO2, with a metal supported thereon. The present invention also relates to an ammonia production method that uses the catalyst for the production of ammonia, disclosed herein, to produce NH3 from NOX and a reductant with one pot in the presence of oxygen without concentrating NOX.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to an ammonia production catalyst, an ammonia production method and production apparatus, and a denitration method and denitration apparatus.

In the selective catalytic reduction reaction denitrification of nitrogen oxides (NO _x ) using ammonia (NH ₃ ) (hereinafter referred to as NH ₃ -SCR denitrification), production, transport, storage and injection of NH ₃ as a reducing agent are included. There is a demand for labor saving and cost reduction as a whole.

The NH ₃ -SCR denitrification process has _{already been applied to various exhaust gas treatment, but all of them require storage and injection equipment for NH 3 as} a reducing agent. need to be transported.
In particular, the production process of _NH3 requires high temperature and high pressure, and also requires high-purity raw materials _N2 and _H2 , and the production of these high-purity raw materials also requires a large amount of energy.

The following non-patent document 1 describes a method of purifying NOx during lean combustion by a mechanism of oxidizing NOx and storing it as nitrate, and reducing and purifying the NOx stored during fuel-rich combustion by reaction with HC and CO. is described. Also, a technique of adding an alkaline substance as a NOx storage material to a conventional three-way catalyst to suppress combustion loss to 1% or less is described.

Non-Patent Document 2 describes a technique of using an H-type mordenite zeolite adsorbent to improve the NOx purification rate under high temperature transient conditions in the NH ₃ -SCR denitrification process.

Non-Patent Document 3 describes a technique that shows an effect of occluding and reducing NOx by adding an element such as palladium to a catalyst in which perovskite (La _1-x Sr _x CoO ₃ ) is supported on an alumina carrier. there is

330 Selections of Japanese Automobile Technology NOx Storage Reduction Three-Way Catalyst Produced by Toyota Motor Corporation, published in August 1994, website https://www.jsae.or.jp/autotech/11-2.php Sakai, M.; Hamaguchi, T.; Tanaka, T. Improving high-temperature NOx conversion in the combined NSR-SCR system with an SCR catalyst mixed with an NH3 adsorbent. Appl. Catal., A: General 2019, 582, 117105 . Onrubia-Calvo, J. A.; Pereda-Ayo, B.; De-La-Torre, U.; Gonzalez-Velasco, J. R. Strontium doping and impregnation onto alumina improve the NOx storage and reduction capacity of LaCoO3 perovskites. , 208-218.

Conventionally, three-way catalysts and _NOx storage reduction (NSR) catalysts have been commercially used for the denitrification process of automobile exhaust gases.
However, all of the conventional catalysts have poor reactivity in a state where _oxygen is always coexistent, such as power plants, waste treatment facilities, and factory exhaust gases. ), it is necessary to detoxify to N ₂ in the absence of oxygen, which corresponds to automobile exhaust gas.
In addition, in selective catalytic reduction reaction denitrification (SCR) of NO _X , a process (EtOH-SCR) centered on Ag/Al ₂ O ₃ catalyst using ethanol as a reducing agent is being worked on. , NH ₃ is by-produced by about 30%. In this catalyst, the by-product _NH3 does not act as a reducing agent, and the loss of _NH3 is a problem for denitrification.
On the other hand, looking at this process as an _NH3 production process, there is a problem that the yield of _NH3 is too low.

In order to solve the above-mentioned problems, the present inventor tackled technical issues with the aim of realizing a process that does not require external procurement of _NH3 , and furthermore, an _NH3 production process other than the conventional Haber-Bosch process. .
The purpose of the present invention is to provide a catalyst for producing ammonia from nitrogen oxides in an exhaust gas atmosphere (in the presence of O ₂ and water vapor) at a high yield, and to provide a technology capable of producing ammonia at a high yield. do.
Another object of the present invention is to provide an ammonia production catalyst whose activity is unlikely to decrease even after long-term use, an ammonia production method using the catalyst, and a nitrogen oxide denitrification method and denitrification equipment.

The gist of the present invention is as follows.
(1) The catalyst for ammonia production of the present invention is a catalyst for producing NH ₃ from NO _X and a reducing agent in the presence of oxygen, in which a metal is supported on a carrier made of TiO ₂ .
(2) In the catalyst for ammonia production of the present invention, it is preferable that the metal supported on the carrier is Ag.
(3) In the ammonia production catalyst of the present invention, the amount of Ag supported on the carrier is preferably 0.7 to 5% by mass of the total amount of the carrier and Ag.
(4) When the catalyst for ammonia production of the present invention is used in the absence of water vapor, the crystal structure of the carrier is preferably an anatase type.
(5) In the ammonia production catalyst according to any one of (1) to (3) of the present invention, when used in the presence of oxygen and water vapor, the support has a rutile crystal structure. It is preferably a metal-supported ammonia production catalyst that produces NH ₃ from NO _X and a reducing agent.
(6) In the catalyst for ammonia production of the present invention, it is preferable that the reducing agent is a hydrocarbon.
(7) In the catalyst for ammonia production of the present invention, it is preferable that the hydrocarbon is C ₃ H ₆ .

(8) The ammonia production method of the present invention uses the catalyst for ammonia production according to any one of (1) to (7), and produces NO X and NO _X in one pot without concentrating NO _X in the coexistence of oxygen and water vapor. It is characterized by producing _NH3 from a reducing agent.
(9) In the ammonia production method of the present invention, the amount of Ag supported on the carrier is 0.7 to 1.5% by mass of the total amount of the carrier and Ag, and the ammonia production catalyst is heated at 400 ° C. or higher. It is preferred to use
(10) In the ammonia production method of the present invention, the amount of Ag supported on the carrier is 1.5 to 5 mass% of the total amount of the carrier and Ag, and the catalyst for ammonia production is heated at a temperature of less than 400 ° C. It is preferred to use
(11) The ammonia production apparatus of the present invention includes the ammonia production catalyst according to any one of (1) to (7) inside a reactor, and the NO X supply unit and the NO _X supply unit on one side of the reactor. The reactor is characterized by comprising a supply section for the reducing agent and an outlet section on the other side of the reactor.

(12) The denitrification method of the present invention comprises mounting the ammonia production catalyst according to any one of (1) to (7) in the front-stage reactor and mounting the NH _-SCR catalyst in the rear-stage reactor, 47.4% or more of NO _X in the exhaust gas in which oxygen and water vapor coexist in the preceding reactor equipped with the ammonia production catalyst is converted to NH ₃ using the ammonia production catalyst and the reducing agent. The remaining NO _X is reduced in the latter reactor using the NH ₃ obtained as a reducing agent, so that denitrification is performed in the latter reactor without externally injecting NH ₃ into the latter reactor. do.

(13) In the denitrification method of the present invention, the amount of Ag supported on the carrier is 0.7 to 1.5% by mass of the total amount of the carrier and Ag, and the ammonia production catalyst is used at 400°C or higher. preferably.
(14) In the denitrification method of the present invention, the amount of Ag supported on the carrier is 1.5 to 5% by mass of the total amount of the carrier and Ag, and the ammonia production catalyst is used at a temperature of less than 400°C. preferably.

(15) In the denitration method according to the present invention, according to any one of (12) to (14), C ₃ H ₆ is used as the reducing agent, and NO _X concentration monitoring is provided downstream of the latter reactor. The residual NO _X concentration is monitored by a meter, the residual NH _{3 concentration is monitored by the NH 3 concentration} monitor provided downstream from the reactor in the latter stage, and the C ₃ H ₆ concentration monitor is monitored. Based on the residual C ₃ H ₆ concentration, the reductant C required to produce the desired NH ₃ from NO _X was calculated using the correlation data of NH ₃ yield and reductant C ₃ H ₆ conversion rate. It is preferable to adjust the amount _{of 3H6} .

(16) The denitrification apparatus of the present invention comprises a front-stage reactor and a rear-stage reactor connected to the front-stage reactor, and the front-stage reactor contains any of (1) to (7). The ammonia production catalyst described above is mounted, the NO _X supply unit and the reducing agent supply unit are provided on one side of the reactor, and the outlet is provided on the other side of the reactor. An NH ₃ -SCR catalyst is installed in the reactor.
(17) In the denitrification apparatus according to (16), C ₃ H ₆ is used as the reducing agent, and the residual NO _X concentration monitored by a NO _X concentration monitor provided downstream from the reactor in the latter stage; _{NH _ _ _ _ _} A regulator that adjusts the amount _of reductant _C3H6 required to produce the desired _{NH3 from NOx} by calculating using the correlation data of ₃ yield and reductant _C3H6 conversion; or A controller is preferably provided.

According to the present invention, _NH3 can be produced from _NOX in the exhaust gas at atmospheric pressure with a high yield, and the energy level of NO is higher than that of _N2. It is possible to provide an ammonia production catalyst and an ammonia production method that can produce NH ₃ with lower energy than the method. Further, according to the present invention, it is possible to provide an ammonia production catalyst and an ammonia production method that can produce ammonia at a high yield.

According to the ammonia production method and the denitrification method according to the present invention, _NH3 can be produced from _NOx in the exhaust gas in which oxygen and water vapor coexist, so that high-purity _N2 can be obtained like the conventional Haber-Bosch method. air cryogenic separator, natural gas reforming process or water electrolysis to obtain _H2 .
According to the denitration method according to the present invention, transportation and storage of the reducing agent _NH3 supplied to the denitration process into the factory exhaust gas, injection equipment for storage and denitration, and infrastructure equipment therefor become unnecessary, contributing to a reduction in denitration costs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing the overall configuration of a denitrification apparatus equipped with a reactor equipped with an ammonia production catalyst according to the present invention; FIG. 2 is a side view showing a reactor equipped with an ammonia production catalyst according to the present invention; FIG. 1 is a schematic configuration diagram showing the overall configuration of a conventional denitrification apparatus equipped with a conventional reactor in which an ammonia-producing catalyst is mounted. FIG. 2 is an image diagram showing a reaction pathway when ammonia production is performed using the catalyst according to the present invention. FIG. 4 is a diagram showing a comparison of the temperature dependence of the NH ₃ yield in the presence/absence of steam coexistence when any of ZrO ₂ , anatase-type TiO ₂ , and rutile-type TiO ₂ is used as a carrier on which Ag is supported. FIG. 10 is a diagram showing the temporal change in _NH3 yield in the absence of water vapor when anatase-type _TiO2 is used as a carrier on which Ag is supported. Effect of water vapor partial pressure on _NH3 yield on Ag-loaded rutile _TiO2 support. Effect of water vapor partial pressure on _NH3 yield on Ag-loaded anatase _TiO2 support. Effect of space velocity (SV) on _NH3 yield on Ag-loaded rutile _TiO2 support. Effect of space velocity (SV) on _NH3 yield on Ag-loaded anatase _TiO2 support. FIG. 10 is a diagram evaluating the effect of reducing the partial pressure of a reducing agent (C ₃ H ₆ ) on a rutile-type TiO ₂ support supporting Ag. FIG. 10 is a diagram evaluating the effect of reducing the partial pressure of a reducing agent (C ₃ H ₆ ) on an anatase-type TiO ₂ support supporting Ag. FIG. ₃ is a diagram evaluating the dependence of catalyst metal (Ag) loading on rutile-type TiO ₂ support on NH 3 yield. Graph evaluating the dependence of catalyst metal (Ag) supported on rutile-type TiO ₂ support on C ₃ H ₆ conversion rate FIG. 4 is a diagram showing the change in C ₃ H ₆ conversion rate with respect to NH ₃ yield of a catalyst in which 2% by mass of Ag is supported on a rutile-type TiO ₂ support. Regarding the residual NO _X concentration with _the environmental monitoring measuring instrument installed in the chimney, etc. of the discharge part shown in FIG. An example of general control _logic for determining _the amount of reducing agent _C3H6 required to produce the desired amount of _NH3 by monitoring the residual NH3 concentration and the _{residual C3H6} concentration at illustration. Fig. 17 shows an apparatus for implementing the control logic shown in Fig. 16 when the process according to the invention is used only for flue gas denitrification and not for _NH3 production;

Hereinafter, the catalyst for ammonia production, the method for producing ammonia, and the apparatus for producing ammonia according to the present embodiment will be described in detail while showing specific examples. In addition, a selective catalytic reduction reaction denitration (hereinafter referred to as NH ₃ -SCR denitration) and a selective catalytic reduction reaction denitration apparatus according to the present embodiment using the ammonia production apparatus will be described together.

FIG. 1 is a schematic configuration diagram showing the overall configuration of an NH ₃ -SCR denitrification system according to this embodiment. The NH ₃ -SCR denitrification system 1 has a reactor 2 for producing ammonia. A reheater 3 for exhaust gas is connected to the upstream side (previous stage side) of the reactor 2 , and an induced draft type ventilator 4 is connected to the upstream side of the reheater 3 .
An exhaust gas supply source 5 from a bag filter or the like connected to an exhaust gas source in a factory or the like is connected to the upstream side of the ventilator 4 . Exhaust gas containing nitrogen oxides (NO _x ) and the like discharged from the exhaust gas supply source 5 passes through the ventilator 4 and the reheater 3 and is supplied to the reactor 2 .
A denitration reactor 6 containing an NH ₃ -SCR catalyst and an ammonia adsorption means 7 are provided on the downstream side (later stage side) of the reactor 2 . The ammonia adsorption means 7 may be, for example, equipment for adsorbing ammonia leaking from the denitrification reactor 6 with activated carbon or the like.
In the configuration of this embodiment, since the exhaust gas from the exhaust gas supply source 5 is processed in the reactor 2 and then sent to the denitrification reactor 6, the exhaust gas supply source 5 is the most upstream device, and the denitrification reactor 6 is downstream. side equipment. An ammonia adsorption means 7 and a discharge section (chimney) 7A are provided downstream of the denitrification reactor 6, and an NH ₃ concentration monitor 6A is connected to a pipe between the denitration reactor 6 and the ammonia adsorption means 7. ing. A NO _X concentration monitor 7B for environmental monitoring is connected to the discharge section 7A, and the NO _X concentration in the exhaust gas discharged from the discharge section 7A can be monitored.
Regarding the NO _X concentration monitor 7B, even if the ammonia adsorption means 7 is omitted, it can be connected to the discharge part 7A. It is also possible to set

Inside the reheater 3, a meandering tube 3a for heat exchange is provided. The inlet side of the serpentine tube 3a is led out of the reheater 3 and connected to a high-pressure steam supply source 8 provided outside the reheater 3. As shown in FIG. A high pressure steam supply source 8 can supply high pressure steam heated to a desired temperature to the serpentine tube 3a. An exhaust pipe 3b is provided on the outlet side of the meandering pipe 3a, and the high-pressure steam that has passed through the meandering pipe 3a can be discharged into the atmosphere from the exhaust pipe 3b.
The flue gas supplied to the reheater 3 from the ventilator 4 is temperature-controlled to a desired temperature by the meandering pipe 3a while passing through the interior of the reheater 3. supplied to

The detailed structure of the reactor 2 is shown in FIG. The reactor 2 has a dome-shaped introduction part 2B on the bottom side of a vertical cylindrical body part 2A, and a dome-shaped lead-out part 2C on the ceiling side. A lead-out pipe 11 is connected to the portion 2C. In the reactor 2, the part where the inlet pipe 10 is connected to the inlet part 2B is the exhaust gas supply part 2E, and the part where the outlet pipe 11 is connected to the outlet part 2C is the gas outlet part 2F.
The inlet pipe 10 is connected to the outlet side of the reheater 3 and the outlet pipe 11 is connected to the inlet side of the NH ₃ -SCR denitrifier 6 .

A supply pipe 12 is connected to a portion of the introduction pipe 10 near the reactor 2 . This supply pipe 12 is connected to a supply source 13 of a reducing agent. Hydrocarbon gas can be used as the reducing agent used here, and for example, propylene gas (C ₃ H ₆ gas) can be used. A portion where the tip of the supply pipe 12 is connected to the introduction pipe 10 functions as a reducing agent supply portion (supply nozzle) 12 a for the reactor 2 .

In the body portion 2A of the reactor 2, a grating 15 is provided as a partition member at a position near the introduction portion 2B. A catalyst layer 17 filled with granular catalyst is provided. A shelf is formed by the grating 15 and the support layer 16, and the catalyst layer 17 is supported by the shelf. The catalyst layer 17 is provided up to near the upper end of the body portion 2A, and the upper end of the catalyst layer 17 is provided with a partition layer 18 in which ceramic balls are spread. The catalyst layer 17 may be a structure in which the catalyst is fixed to a honeycomb made of metal or ceramic by coating or the like, or a structure in which the catalyst is formed into a shape such as a honeycomb. In that case, the retention layer 16 and the partition layer 18 may be omitted.

In the reactor 2 , the exhaust gas introduced into the body portion 2</b>A from the introduction pipe 10 passes through the gaps between the ceramic balls, reaches the catalyst layer 17 , and passes through the gaps between the catalyst particles in the catalyst layer 17 . The gas that has passed through the gaps between the catalyst particles of the catalyst layer 17 passes through the gaps of the ceramic balls and reaches the lead-out pipe 11 . The gas reaching the outlet pipe 11 is supplied to the NH ₃ -SCR denitrifier 6 .
The NH ₃ -SCR denitration device 6 contains a catalyst suitable for NH ₃ -SCR denitration, such as activated carbon.

In the reactor 2, a first communication pipe 19 passing through the side wall of the body portion 2A is provided in a part of the body portion 2A. is connected.
A second communication pipe 21 is provided on the bottom side of the reactor 2 and penetrates the peripheral wall of the introduction portion 2B. A third communication pipe 22 is provided on the upper side of the outlet portion 2C and penetrates the peripheral wall of the outlet portion 2C.
A pressure detection sensor of a pressure detector 23 is installed in the introduction portion 2B via the second communication pipe 21 . A pressure detection sensor of a pressure detector 25 is installed in the lead-out portion 2C via the third communicating pipe 22. As shown in FIG.

The pressure detector 23 is a detector that detects pressure on the bottom side of the reactor 2 , and the pressure detector 25 is a detector that detects pressure on the ceiling side of the reactor 2 . The pressure measurement on the bottom side of the reactor 2 corresponds to the pressure measurement on the upstream side of the catalyst layer 17 , and the pressure on the top side of the reactor 2 corresponds to the pressure measurement on the downstream side of the catalyst layer 17 .
The pressure detectors 23 and 25 are connected to a control device 26 such as a personal computer and a programmable controller, and measure and record the upstream pressure and the downstream pressure of the catalyst layer 17 measured by the pressure detectors 23 and 25, and It is configured so that calculation results such as differential pressure between those pressures can be recorded and grasped.

As the catalyst 17 applied to the reactor 2, as a first example, catalyst particles in which metal particles such as Ag are carried on the surface of carrier particles made of rutile-type titanium oxide (TiO ₂ ) can be applied. As a second example, the catalyst 17 can be catalyst particles in which metal particles such as Ag are supported on the surfaces of carrier particles made of anatase titanium oxide (TiO ₂ ). As a third example, the catalyst 17 can be catalyst particles in which metal particles such as Ag are supported on the surfaces of carrier particles made of zirconium oxide (ZrO ₂ ). Alternatively, mixed particles of any of the catalyst particles of the first to third examples can be used.
When producing catalyst particles in which Ag is supported on the carrier particles described above, each carrier particle is dissolved in an aqueous solution of silver nitrate to obtain a predetermined amount of Ag supported. The amount of Ag supported can be adjusted by adjusting the concentration of the silver nitrate aqueous solution.

In the catalyst 17 described above, rutile-type titanium oxide or anatase-type titanium oxide may be used as a carrier, and Ag particles may be carried on the surface of the carrier. In this case, the preferable amount of Ag to be supported can be selected in the range of 0.7 to 5% by mass with respect to the total mass of the Ag to be supported and the support.
When the catalyst 17 is used in a temperature range of less than 400° C., the supported amount of Ag is preferably 1.5 to 5 mass %.
When the catalyst 17 is used in a temperature range of 400° C. or higher, the supported amount of Ag is preferably 0.7 to 1.5 mass %.
The carrier particles having the above-mentioned supported amount are recovered by evaporation to dryness and calcined in the air at about 500° C. for several hours to obtain the desired catalyst particles.
As an example, the particle size of the catalyst 17 can be adjusted to approximately 0.3 to 0.6 mm.

In the present specification, when describing a specific range such as a range of component content or a particle size range, when specifying the upper and lower limits using "~", unless otherwise specified, the upper and lower limits is meant to be included in its scope. Therefore, the aforementioned 0.7 to 5 mass% means a range of 0.7 mass% or more and 5 mass% or less, and 1.5 to 5 mass% means a range of 1.5 mass% or more and 5 mass% or less. means

In the NH ₃ -SCR denitration device 1 shown in FIG. 1, the reactor 2 corresponds to an ammonia production device, and the NH ₃ -SCR denitration device 1 is mainly composed of the reactor 2 and the NH ₃ -SCR denitration device 6. .
The exhaust gas from the exhaust gas supply source 5 is supplied to the reheater 3a by the fan 4, the temperature of the exhaust gas is adjusted by the high-pressure steam supplied to the meandering pipe 3a, and the exhaust gas after the temperature adjustment is introduced into the reactor 2 through the introduction pipe 10. supply to When exhaust gas is supplied to the reactor 2 through the introduction pipe 10 , the exhaust gas is mixed with a hydrocarbon gas as a reducing agent through the supply portion 12 a of the supply pipe 12 . Hydrocarbon gas can apply propylene gas ( _C3H6 ), for _example .

Exhaust gases as applied here include, for example, NO, O ₂ , CO, CO ₂ , H ₂ O, N ₂ , SO ₂ and the like.
The exhaust gas contacts the catalyst 17 housed inside the reactor 2 in a predetermined temperature atmosphere, and reacts as shown in the following reaction formula to produce ammonia (NH ₃ ).
NO+ _C3H6 +13/ _4O2 → _NH3 + _3CO2 + ₃ / _2H2O

The following equations (1) to (5) can be considered as assumptions of the reaction mechanism in which the exhaust gas is converted to NH ₃ by contact with the catalyst 17. Summing the equations leads to the above reaction equation.
(1) NO+1/ _2O2 → _NO2
(2) _H2O →H+OH
(3) _NO2 +OH→ _HNO3
(4) Ag+ _HNO3 → _AgNO3 +1/ _2H2
(5) _AgNO3 + _C3H6 +9/ _4O2 →Ag+ _NH3 + _3CO2 +3 _{/ 2H2O}
Exemplary exhaust gas compositions include NO: 980 to 1020 ppm, O ₂ : 9.44 to 10.21%, H ₂ O: 0% or 5.0%, and N ₂ : balance.

Ammonia (NH ₃ ) can be produced in a high yield in the gas that has passed through the catalyst 17 of the reactor 2 . As shown in the examples described later, for example, when the Ag loading amount on the carrier is 1 to 1.5% by mass in the temperature range around 400 ° C., ammonia is produced from the exhaust gas at a high yield of 47.4% or more. can.

As shown in the reaction scheme above, NO is oxidized to NO ₂ by Ag on the support surface.
In addition, the —OH group on the surface of the support made of anatase-type TiO ₂ is highly reactive with NO ₂ , and NH ₃ is produced via nitrate radicals. In addition, in the case of a support made of rutile TiO ₂ with low reactivity of the surface —OH group, OH and H are generated on the support surface from the coexisting water vapor, and OH and NO ₂ generated from the coexisting water vapor pass through the nitrate group. NH ₃ is produced.
Therefore, according to the above results, it is possible to proceed the reaction for ammonia production in one pot without concentrating NO _X in the coexistence of oxygen and water vapor.
Therefore, it is possible to provide an ammonia production method for producing _NH3 from _NOX and a reducing agent.

In the method for producing ammonia using the above-mentioned catalyst, _NH3 can be produced from _NOX in the exhaust gas at atmospheric pressure, and the energy level of NO is higher than that of _N2 .・It has the feature that _NH3 can be produced with lower energy than the Bosch method. This reaction route image will be described below with reference to FIG.

As shown in Fig. 4, the binding energy of the elements N and N in _N2 is 941.6 kJ/mol. The binding energy of the elements N and H in _NH3 is 444.1 kJ/mol. In the Haber-Bosch method, it is necessary to react N ₂ to NH ₃ in a high-temperature and high-pressure environment, as indicated by the upward arrow on the left side of FIG.
In contrast, the binding energy between the elements N and O in NO is 626.8 kJ/mol. In the ammonia production method of the present embodiment, it can be expressed as the above reaction formula for converting NO to _NH3 , so it can be understood that _NH3 can be produced with lower energy than the Haber-Bosch method.

In the ammonia production method described above, _NH3 can be produced from _NOX in _the exhaust gas in which oxygen and water vapor coexist. No natural gas reforming process or water electrolyzer to obtain _H2 is required.
In addition, transportation and storage of the reducing agent _NH3 supplied to the denitrification process of the factory exhaust gas, injection equipment for storage and denitrification, and infrastructure equipment therefor become unnecessary, contributing to a reduction in denitrification costs.

In the NH ₃ -SCR denitrification apparatus 1 of this embodiment, NH ₃ produced in the reactor 2 can be sent to the denitrification reactor 6 through the outlet pipe 11 .
In the denitration reactor 6 containing the NH ₃ -SCR catalyst, the NH ₃ -SCR catalyst performs denitration treatment under the supplied reducing agent NH ₃ . The NH ₃ -SCR catalyst, which can be used as an example with activated carbon, is removed by a reaction that can be represented by the following equation.
NO+ _NH3 +1/ _2O2 → _N2 +3/ _2H2O

FIG. 3 shows a schematic configuration diagram of a selective catalytic reduction reaction denitration device (NH ₃ -SCR denitration device) based on the conventional Haber-Bosch method.
A conventional NH ₃ -SCR denitrification apparatus 30 has an exhaust gas supply source 32, a ventilator 33, a reheater 34, and a high-pressure steam supply source 35 on the front stage side of a denitrification reactor 31 containing an NH ₃ -SCR catalyst. . The exhaust gas supply source 32 has a configuration equivalent to that of the exhaust gas supply source 5 described above, and the ventilator 33 can adopt a configuration equivalent to that of the ventilator 4 described above. The reheater 34 has the same configuration as the reheater described above, and the high pressure steam supply source 35 can have the same configuration as the high pressure steam supply source 8 described above.

In addition to these components, the conventional NH ₃ -SCR denitrification apparatus 30 requires transportation and storage of the reducing agent NH ₃ , injection equipment for denitrification, and infrastructure equipment therefor.
As shown in FIG. 3, nitrogen from a cryogenic separator 41 equipped with an air supply means 40, natural gas supply 42 and hydrogen from a steam reformer 45 equipped with a water supply 43 are used to produce the Haber-Bosch process. A reactor 46 is required to carry out the A storage tank 48 for storing the ammonia 47 produced in the reactor 46, a tank truck 49 for transporting the ammonia, a relay storage station 50 for the ammonia transported by the tank truck 49, and a dilution tank 51 are required. Furthermore, a tank truck 52 for transporting diluted ammonia from the dilution tank 51 to the site where the denitrification reactor 31 is installed, a water tank 53 and an ammonia vaporizer 54 installed near the site are required. Ammonia can be supplied to the denitration reactor 31 by sending ammonia and compressed air from the ammonia tank 53 on site to the ammonia vaporizer 54 .

As described above, in the conventional NH ₃ -SCR denitrification apparatus 30, in order to supply NH ₃ to the denitrification reactor 31, various NH ₃ transportation and storage equipment, denitrification injection equipment, and infrastructure equipment therefor are used. was necessary. On the other hand, a plurality of facilities and devices that were required in the conventional NH ₃ -SCR denitration system 30 are no longer required in the NH ₃ -SCR denitration system 1 of the embodiment shown in FIG. contribute to reduction.
In addition, since the above-mentioned catalyst does not lose its activity even after repeated use, the NH ₃ -SCR denitrification apparatus 1 can be operated in a stable state without frequent replacement of the catalyst. Reactor 2 can also produce _NH3 from _NOx at low cost and in high yield.

Hereinafter, the present invention will be described in more detail with reference to examples, but the conditions in the examples are examples of conditions adopted to confirm the feasibility and effect of the present invention, and the present invention is based on this one condition. Examples are not limiting. Various conditions can be adopted in the present invention as long as the objects of the present invention are achieved without departing from the gist of the present invention.

"catalyst carrier"
TiO ₂ (JRC-TIO-16and-17) and ZrO ₂ (JRC-ZRO-6) were prepared. JRC-TIO-16, which is rutile-type TiO ₂ , is manufactured by Sakai Chemical Industry Co., Ltd., has a specific surface area of 109 m ² /g, and becomes 30-50 m ² /g by firing after supporting Ag. JRC-TIO-17 used P-25 manufactured by Degussa (Germany). P-25 was prepared by Evonik Japan Co., Ltd. as 70% anatase carrier + 20% rutile carrier + 10% amorphous carrier (hereinafter P-25 may be referred to as anatase TiO ₂ ). The specific surface area of JRC-TIO-17 is 50 m ² /g regardless of whether Ag is supported or not.
JRC-ZRO-6 is amorphous hydrated ZrO ₂ prepared by the hydrolysis method by Daiichi Kigenso Kagaku Kogyo Co., Ltd. and has a specific surface area of 279 g/m ² . After Ag-supported and calcined, it changes to a tetrahedral crystal phase, and the specific surface area becomes 94 g/m ² .

"Catalyst preparation (metal support)"
- Method of loading Ag When loading Ag, each carrier was dissolved in an aqueous _AgNO3 solution to adjust the amount of loaded Ag to a predetermined amount (for example, 5% by mass of the total). The solid matter recovered from the aqueous solution by evaporation to dryness was calcined in the atmosphere at 500° C. for 4 hours, and the calcined particles were mechanically crushed to prepare a particle size of 0.3 to 0.6 mm.

"Analysis of catalysts"
The crystal structure and Ag particle size of the catalyst were analyzed using X-ray diffraction (D2_Phaser, Brucker, USA), Cu Kα radiation and Ni filter.
"Evaluation of Catalytic Reaction"
Catalytic activity was evaluated using a quartz tube reactor (outer diameter 14 mm, tube thickness 1 mm, length 700 mm). The catalyst was mounted in the center of the reactor. The catalyst volume was used to measure the space velocity (SV) and was typically loaded with 0.6 mL (SV=10000 h ⁻¹ ) (weighing about 0.3-0.5 g). The reaction temperature was measured at the center of the catalyst packed bed using a sheath tube with a sheath tube. All reaction evaluations were performed at atmospheric pressure.

A mixed gas of NO, C ₃ H ₆ , O ₂ , H ₂ O, and N ₂ was supplied from the top of the reactor at 100 mL/min (when SV = 10000 h ⁻¹ ), and the post-reaction gas was supplied from the bottom of the reactor to FT It was introduced into a 2.4 m gas cell in an IR (Fourier Transform Infrared Spectrophotometer) system, and the constituents were measured as NH ₃ and C ₃ H ₆ .

The composition, flow rate conditions, etc. of the mixed gas used for the evaluation are as follows. NO: 980-1020 ppm, C ₃ H ₆ : 0.50-0.52%, O ₂ : 9.44-10.21%, H ₂ O: 0% or 5.0%, N ₂ : balance, total Flow rate: 100.0-102.5 mL/min, amount of catalyst: 0.6 mL (SV: 10000-10300 h ^-1 ).

The average NH ₃ production rate and average C ₃ H ₆ consumption rate over 30 minutes at a given temperature setting were used for catalytic activity evaluation. The NH ₃ yield (Y _NH3 ) and the C ₃ H ₆ consumption rate (X C 3 _{H 6} ) were calculated by the following equations (1) and (2) using the concentrations and amounts of NO and C ₃ H 6 .
In addition, SV = Space Velocity (spatial velocity) is shown,
SV [h ⁻¹ ]=supply gas flow rate [mL/h]/catalyst amount [mL].

FIG. 5 shows the NH ₃ yield in the presence/absence of water vapor when ZrO ₂ , anatase-type TiO ₂ (P-25), or rutile-type TiO ₂ is used as the support in the Ag-supported ammonia production catalyst. Temperature dependence is shown in comparison.
As shown in FIG. 5, in a wide temperature range of 200° C. to 380° C., the reaction for producing ammonia proceeded in all samples, and ammonia was produced.
From the results shown in FIG. 5, there is a peak of _NH3 yield in a specific temperature range in any sample, and the _NH3 yield gradually decreases when the temperature changes from the peak temperature range to the low temperature side or the high temperature side. I found out.

It was also found that ammonia can be produced with a high yield of about 30% when using catalysts in which Ag is supported on an anatase-type TiO ₂ (P-25) or rutile-type TiO ₂ carrier. It should be noted that, as in the test results of this time, the progress of the reaction to produce ammonia using the above-mentioned catalyst itself is a new finding, and it can be seen that this finding can provide a technology that can produce ammonia at a high yield.
Therefore, according to the above results, the reaction for producing ammonia could proceed in one pot without concentrating NO _X in the coexistence of oxygen regardless of the presence or absence of water vapor. Therefore, it can be seen that an ammonia production method for producing _NH3 from _NOX and a reducing agent can be provided.

FIG. 6 shows the time course of the _NH3 yield in the absence of water vapor when using an anatase-type _TiO2 as the support in the Ag-supported catalyst for ammonia production.
From the results shown in FIG. 6, in contrast to the results shown in FIG. 5, it was found that the ammonia production catalyst in which Ag was supported on an anatase-type TiO ₂ carrier tends to deteriorate over time when water vapor is not present. rice field.

FIG. 7 shows the effect of reaction temperature and water vapor partial pressure on _NH3 yield in the catalyst for ammonia production in which Ag is supported on rutile-type _TiO2 support.
From the results shown in FIG. 7, it can be seen that the NH ₃ yield is low at a water vapor partial pressure of 0%, but the NH ₃ yield is significantly improved at a water vapor partial pressure of 2.5% to 15%. . In particular, under the condition of water vapor partial pressure of 10% to 15%, NH ₃ yield of over 30% was obtained when the temperature condition was selected.
The condition of water vapor partial pressure of 0% corresponds to the case of using dry gas as exhaust gas.
It should be noted that the progress of the reaction to produce ammonia using the catalyst described above, as in the present test results, itself is a new finding. Therefore, even when dry gas with a low yield is used, the fact that the ammonia production reaction proceeds using the above-described catalyst itself has technical significance.

FIG. 8 shows the effect of reaction temperature and water vapor partial pressure on _NH3 yield in the catalyst for ammonia production in which Ag is supported on an anatase-type _TiO2 support.
From the results shown in FIG. 8, it can be seen that under the condition of water vapor partial pressure of 0% to 10%, a high NH ₃ yield can be obtained by selecting the reaction temperature.
However, under the condition of 0% water vapor partial pressure, the catalyst for ammonia production using the anatase-type TiO ₂ support shows deterioration over time as shown in FIG. is considered to be disadvantageous to

Figure 9 shows the effect of space velocity (SV) on _NH3 yield for the catalyst for ammonia production with Ag supported on rutile-type _TiO2 support.
From the results shown in FIG. 9, the NH ₃ yield peak exists in the temperature range of 280 to 370° C. for all samples, and the NH ₃ yield gradually decreases as the temperature changes from the peak temperature range to the lower or higher temperature side. was found to decrease to Also, these proportions showed similar trends at any space velocity in the tested range.

FIG. 10 shows the effect of space velocity (SV) on _NH3 yield for ammonia production catalysts with Ag supported on anatase-type _TiO2 support.
From the results shown in FIG. 10, there is a peak of NH ₃ yield in the temperature range of 320 to 350 ° C in all samples, and the NH ₃ yield decreases when the temperature changes from the peak temperature range to the lower or higher temperature side. I found out to do. Also, these proportions showed similar trends at any space velocity in the tested range.

FIG. 11 shows the effect of reducing the partial pressure of the reducing agent (C ₃ H ₆ ) in the ammonia production catalyst in which Ag is supported on a rutile-type TiO ₂ support.
From the results shown in FIG. 11, there is a peak of NH ₃ yield in the temperature range of 330 to 360° C. for all samples, and the NH ₃ yield decreases when the temperature changes from the peak temperature range to the lower or higher temperature side. I found out to do.
The results shown in FIG. 11 indicate that the NH ₃ yield changes little at any reaction temperature when the partial pressure of the reducing agent varies from 0.28% to 0.51%.

FIG. 12 shows the effect of reducing the partial pressure of the reducing agent (C ₃ H ₆ ) in the catalyst for ammonia production in which Ag is supported on an anatase-type TiO ₂ support.
From the results shown in FIG. 12, there is a peak of NH ₃ yield in the temperature range of 320 to 340 ° C in all samples, and the NH ₃ yield decreases when the temperature changes from the peak temperature range to the lower or higher temperature side. I found out to do.
The results shown in FIG. 12 show that the NH ₃ yield decreases significantly at any reaction temperature when the partial pressure of the reductant is decreased from 0.51% to 0.28%.

FIG. 13 shows the results of evaluation of the dependence of catalyst metal (Ag) supported amount on NH ₃ yield and the temperature dependence of an ammonia production catalyst in which Ag is supported on a rutile-type TiO ₂ support.
The results shown in FIG. 13 show that the NH ₃ yield varies depending on the amount of Ag supported on the support and the reaction temperature.
Incidentally, "1st", "2nd", "3rd" and "4th" shown in FIG. It is also the number of times the carrier used in the test was exposed to high temperatures around 350 to 500°C.

For example, the data of “1.5 wt% Ag_1st” shown in FIG. 390° C.→400° C.→410° C.→430° C.→460° C., and a similar evaluation test was performed to obtain temperature dependency results.
After that, without changing the catalyst, an evaluation test was performed at 270°C by the method described in "Catalytic reaction evaluation", and then 280°C → 290°C → 300°C → 310°C → 320°C → 330°C → 340°C → 350°C. → 360°C → 370°C → 380°C → 390°C → 400°C → 410°C → 420°C → 430°C → 440°C → 450°C → 460°C. The temperature dependence result is the data indicated by "1.5 wt % Ag 2nd" shown in FIG.

When the amount of Ag supported on the rutile-type _TiO2 support is 0.7 to 1.5 mass% of the total amount of the support and Ag, the _NH3 yield is better when the ammonia production catalyst is used at a temperature of 400 °C or higher. found to be high. Therefore, when the amount of Ag supported on the rutile-type TiO ₂ support is 0.7 to 1.5% by mass, it is preferable to use the catalyst for ammonia production at a temperature of 400° C. or higher. Although the desired catalyst temperature varies depending on the amount of Ag supported, it can generally be selected in the range of 400 to 500°C.
It can be seen that an excellent NH ₃ yield of over 47.4% can be obtained by adjusting the catalyst temperature when the Ag loading on the rutile-type TiO ₂ support is between 0.7 and 1.0 wt%.

In addition, when the amount of Ag supported on the rutile-type TiO ₂ support is 1.5 to 5% by mass of the total amount of the support and Ag, the NH ₃ yield is better when the ammonia production catalyst is used at a temperature of less than 400 °C. found to be high. Therefore, when the amount of Ag supported on the rutile-type TiO ₂ support is 1.5 to 5% by mass, it is preferable to use the catalyst for ammonia production at a temperature of less than 400°C.

FIG. 14 shows the results of evaluating the dependence of the amount of catalyst metal (Ag) supported on the conversion rate of C ₃ H ₆ in a catalyst for ammonia production in which Ag is supported on a rutile-type TiO ₂ support.
From the results shown in FIG. 14, it was found that the C ₃ H ₆ conversion rate changed depending on the amount of Ag supported on the carrier and the reaction temperature. It can be understood that the high C ₃ H ₆ conversion rate improves the reactivity.

FIG. 15 shows the change in C ₃ H ₆ conversion rate with respect to NH ₃ yield of a catalyst in which 2% by mass of Ag is supported on a rutile-type TiO ₂ support.
_A very strong correlation was shown between _NH3 yield and _C3H6 conversion.

"Material balance study when applying _NH3 conversion process under coexistence of oxygen"
In the NH ₃ -SCR denitrification device 1 of the present embodiment shown in FIG. 1, the following equations (1) to (5) are taken into consideration as a reaction mechanism in which the exhaust gas contacts the catalyst 17 and is converted to NH ₃ . It was explained that the following reaction formula can be derived by summing each formula shown in (1) to (5).
(1) NO+1/ _2O2 → _NO2
(2) _H2O →H+OH
(3) _NO2 +OH→ _HNO3
(4) Ag+ _HNO3 → _AgNO3 +1/ _2H2
(5) _AgNO3 + _C3H6 +9/ _4O2 →Ag+ _NH3 + _3CO2 +3 _{/ 2H2O}
Reaction formula: NO+ _C3H6 +13/ _4O2 → _NH3 + _3CO2 + ₃ / _2H2O

Therefore, based on this relationship, the material balance when applying the NH ₃ conversion process in the presence of oxygen will be examined below.
In the NH ₃ -SCR denitrification apparatus 1 shown in FIG. 1, exhaust gas at 170° C. is supplied from the exhaust gas supply means 5, reheated to 350.1° C. by the reheater 3, and introduced into the reactor 2 through the introduction pipe 10. , and ₄₀ ° C. is supplied as a reducing agent from the inlet pipe ₁₀ to the reactor 2 via the supply pipe 12 .
It is assumed that the temperature of the catalyst layer 17 is 350.degree. C., and that the temperature of the gas becomes 349.8.degree.

In this case, for NO, C ₃ H ₆ , O ₂ , CO, CO ₂ , H ₂ O, N ₂ , NH ₃ , SO ₂ , HCl, and Ar, the amount before regeneration heating, the amount after reheating, and the reducing agent The amount, post-NH ₃ conversion amount, injected NH ₃ amount, and post-NH ₃ -SCR denitrification amount are listed in Table 1 below.
In the above case, it can be estimated that the _NH3 yield _is 47.48%, the denitration rate is 90.4%, the _C3H6 conversion rate is 93.6%, and the _NH3 leak is less than 5 ppm.

After grasping the above relationship, the following control can be performed in the NH ₃ -SCR denitrification apparatus 1 .
Using the correlation data between the NH _{3 yield} and the reducing agent C ₃ H ₆ conversion rate as shown in FIG. Based on the residual NO _X concentration monitored by the , the amount of reducing agent C ₃ H ₆ required to produce the desired NH ₃ is determined from the amount of NO _X contained in the exhaust gas, and the appropriate reduction is performed. The amount _of agent _C3H6 can be adjusted.

In the NH ₃ -SCR denitrification device 1 shown in FIG. 1, the ammonia adsorption means 7 may be omitted. In this case, based on the residual _NH3 concentration monitored by the NO _X concentration monitor 7B for environmental monitoring connected to the chimney of the discharge section 7A of FIG. 1, the NO _X amount contained in the exhaust gas Ask for Then, using the correlation data described above, the amount of reducing agent _C3H6 required to produce the desired _{NH3 is} determined from the amount of _NOX described above, and the amount of reducing agent _C3H6 is adjusted appropriately _. be able to.

In the NH ₃ -SCR denitrification apparatus 1 shown in FIG. 1, when the ammonia adsorption means 7 is provided, an NO _X concentration monitor 7B for environmental monitoring connected to the pipe in front of the ammonia adsorption means 7 may be provided. In this case, based on the monitored residual NH ₃ concentration, the amount of NO _X contained in the exhaust gas is obtained, and using the above-mentioned correlation data, the desired amount of NH ₃ is produced from the above-mentioned NO _X amount. The amount of reducing agent C ₃ H ₆ required can be determined and adjusted to the appropriate amount of reducing agent C ₃ H ₆ .

In the case _of the NH ₃ -SCR denitrification device 1 shown _in FIG. The remaining NH ₃ concentration can be monitored by the NH ₃ concentration monitor 6A installed on the pipe. Also, the residual C ₃ H ₆ concentration can be monitored by the C ₃ H ₆ concentration monitor 6B.

FIG _{. 17 shows a modification of the NH 3 -SCR} denitrification device 1 shown in FIG. NH ₃ concentration monitor 6A and C ₃ H ₆ concentration monitor 6B are connected to the discharge part 7A.
In the absence of the ammonia adsorption means 7 as shown in FIG. 17, both the NO _X concentration and the NH ₃ concentration are monitored by the NH ₃ concentration monitor 6A and the C ₃ H ₆ concentration monitor 6B. and the NO _X concentration monitor 7B.

In the NH ₃ -SCR denitrification device 60 of FIG. 17, a flow control valve 61 is incorporated in the reducing agent supply source 13, and an arithmetic device (regulator) 62 capable of controlling the flow control valve 61 is provided. The amount of reducing agent sent from the supply source 13 to the reactor 2 on the upstream side can be adjusted by adjusting the opening degree of the flow control valve 61 according to the calculation result of the calculation device 62 .
In addition, the residual NO _X concentration observation result, the residual NH ₃ concentration observation result, and the C ₃ H ₆ concentration observation result by the NO _X concentration monitor 7B, the NH ₃ concentration monitor 6A, and the C ₃ H ₆ concentration monitor 6B are all It is input to the arithmetic device 62 . The calculation device 62 adjusts the supply amount of the reducing agent from the supply source 13 by adjusting the flow control valve 61 according to the calculation result described later based on the above-mentioned residual NO _X concentration observation result and residual NH ₃ concentration observation result. Arithmetic device 62 is applicable to a personal computer, a programmable controller, or the like, which is capable of storing information and having functions capable of performing calculations and judgments according to the stored information.
The flow control valve 61 may be an electrically operated valve or a pneumatically operated valve.

For example, from the type of ammonia production catalyst, the amount of NO _X depending on the reaction temperature _, etc., the relationship in FIG. Stored and based on this information, the calculations contained in the control _logic shown _{in FIG} . The valve 61 can be operated to adjust the supply amount of the reducing agent.
The flow control valve 61 may be an electrically operated valve or a pneumatically operated valve.

In _addition , when a rutile-type TiO ₂ carrier supporting Ag other than 2% by mass is used, the same relationship as the relationship shown in FIG. , may be stored in the arithmetic unit 62 . Alternatively, when a rutile-type _TiO2 carrier carrying Ag other than 2% by mass and a rutile-type TiO2 carrier carrying ₂ % by mass of Ag are mixed and used, a carrier for testing according to the mixing ratio is used. 15 is obtained in advance and stored in the arithmetic unit 62, and this information is preferably used.
Therefore, in the NH ₃ -SCR denitrification device 60 shown in FIG. 17, the amount of NO _X contained in the exhaust gas is grasped, and the amount of the reducing agent C ₃ H ₆ supplied to the reactor 2 is determined and adjusted. can produce NH ₃ in desirable yields.

FIG. 16 shows an example of a schematic control logic when using the NH ₃ -SCR denitrification device 60 shown in FIG. 17 and controlling the supply amount of the reducing agent (C ₃ H ₆ ) to produce a desired amount of NH ₃ . It is a flow chart.
The residual NO _X concentration observation result is sent from the NO _X concentration monitor 7B to the arithmetic device 62 (first step ST1), and the residual NH ₃ concentration observation result is sent from the NH ₃ concentration monitor 6A to the arithmetic device 62 (second step ST1). step ST2).
In the arithmetic unit 62, when the denitration rate in the reactor 6 is p×100%, the relationship of NH ₃ amount consumed in denitration in the reactor 6={p/1−p}×the amount of residual NO _X in the discharge section is stored. Therefore, the amount of NH ₃ to be produced in the reactor 2 can be calculated based on the result obtained in the first step ST1 and the result obtained in the second step ST2 (third step ST3).

The calculated value calculated in the third step ST3 is recognized as the amount of NH3 to be produced in the reactor 2 in the fourth step ST4, and the _amount of _NH3 to be produced in the reactor 2 in the fifth step ST5/the amount of generated _NOx Since the NH ₃ yield is known in the sixth step ST6 from the relationship, the C ₃ H ₆ conversion rate can be calculated in the eighth step ST8 using the correlation equation shown in FIG. 15 in the seventh step ST7.

Further, in the arithmetic device 62, the residual C ₃ H ₆ concentration observation result is sent from the C ₃ H ₆ concentration monitor 6B to the arithmetic device 62 (ninth step ST9), and the C ₃ H ₆ conversion calculated in the eighth step ST8 Since the relationship of residual C ₃ H ₆ concentration / (1 - C ₃ H ₆ conversion rate / 100) = C ₃ H ₆ supply amount is stored together with the rate, the required C ₃ H ₆ The amount to be added is determined in a tenth step ST10 and can be recognized as shown in an eleventh step ST11.
For example, FIG. 15 shows changes in C ₃ H ₆ partial pressure with respect to NH ₃ yield of a catalyst in which 2% by mass of Ag is supported on a rutile-type TiO ₂ support, as described above. Therefore, based on the relationship y=1.9744X-5.7557 obtained from the relationship shown in FIG. 15, the amount of C ₃ H ₆ added can be determined from the NH ₃ yield.
Since the amount of NO _X generated changes sequentially, the amount of NO _X generated is monitored over time as shown in the twelfth step ST12, repeatedly used in the calculation of the fifth step ST5, and used in the calculations of the sixth step ST6 and thereafter. Stable control can be performed by using them sequentially.

DESCRIPTION OF SYMBOLS 1... selective catalytic reduction reaction denitrification apparatus ( _NH3 -SCR denitrification apparatus), 2...reactor (ammonia production apparatus), 2A...body part, 2B...introduction part, 2C...outlet part, 2E...supply part, 2F... Exit part 3 Reheater 5 Exhaust gas supply means 6 (NH ₃ -SCR) denitrification reactor 10 Inlet pipe 11 Outlet pipe 12 Supply pipe 12a Supply part (supply nozzle ), 17... Catalyst layer, 20... Temperature measuring means, 23, 25... Pressure detector, 26... Control device, 62... Arithmetic device (control device).

Claims (17)

A catalyst for ammonia _production that produces _NH3 from NOX and a reducing agent in the presence of oxygen, in which a metal is supported on a carrier made of _TiO2 . 2. The catalyst for ammonia production according to claim 1, wherein the metal supported on said carrier is Ag. 3. The ammonia production catalyst according to claim 2, wherein the amount of Ag supported on said carrier is 0.7 to 5% by mass of the total amount of said carrier and said Ag. The catalyst for ammonia production according to any one of claims 1 to 3, wherein the crystal structure of the support used in the absence of water vapor is anatase. The ammonia according to any one of claims 1 to 3, wherein NH ₃ is produced from NO _X and a reducing agent in the coexistence of oxygen and water vapor, wherein a metal is supported on a support having a rutile crystal structure. manufacturing catalyst. 6. The ammonia production catalyst according to any one of claims 1 to 5, wherein the reducing agent is a hydrocarbon. 7. The ammonia production catalyst according to claim ₆ , wherein the hydrocarbon is _C3H6 . Ammonia for producing NH ₃ from NO _X and a reducing agent in one pot without concentrating NO _X in the coexistence of oxygen and water vapor using the catalyst for producing ammonia according to any one of claims 1 to 7. Production method. The ammonia production method according to claim 8, wherein the amount of Ag supported on the carrier is 0.7 to 1.5 mass% of the total amount of the carrier and the Ag, and the ammonia production catalyst is used at 400 ° C. or higher. . The ammonia production method according to claim 8, wherein the amount of Ag supported on the carrier is 1.5 to 5 mass% of the total amount of the carrier and the Ag, and the ammonia production catalyst is used at a temperature of less than 400 ° C. . The ammonia production catalyst according to any one of claims 1 to 7 is provided inside a reactor, and one side of the reactor is provided with the NO _X supply unit and the reducing agent supply unit, An ammonia production apparatus having an outlet on the other side of the reactor. The catalyst for ammonia production according to any one of claims 1 to 7 is mounted in the front reactor, the NH ₃ -SCR catalyst is mounted in the rear reactor, and the front reactor equipped with the ammonia production catalyst is mounted. In the reactor, 47.4% or more of NO _X in the exhaust gas in which oxygen and water vapor coexist is converted to _NH3 using the catalyst for ammonia production and the reducing agent, and the converted _NH3 is used as the reducing agent in the latter stage. A method of denitration in which residual _NOx is reduced in the reactor to denitrate in the latter reactor without external injection of _NH3 into the latter reactor. 13. The denitrification method according to claim 12, wherein the amount of Ag supported on the carrier is 0.7 to 1.5% by mass of the total amount of the carrier and Ag, and the ammonia production catalyst is used at 400° C. or higher. 13. The denitrification method according to claim 12, wherein the amount of Ag supported on the carrier is 1.5 to 5% by mass of the total amount of the carrier and Ag, and the ammonia production catalyst is used at a temperature of less than 400°C. Using C ₃ H ₆ as the reducing agent, the residual NO _X concentration monitored by the NO _X concentration monitor provided downstream from the latter reactor, and the NH concentration provided downstream from the latter reactor Based on the residual _{NH3 concentration monitored by the 3 concentration} monitor _and the residual _C3H6 concentration monitored by the _C3H6 concentration _monitor , the _NH3 yield and the reducing agent _C3H6 conversion rate were calculated _. Denitrification according to any one of claims 12 to 14, wherein the amount of reducing agent C ₃ H ₆ required to produce the desired NH ₃ from NO _X is adjusted by calculating using the correlation data. Method. comprising a front reactor and a rear reactor connected to the front reactor,
The catalyst for ammonia production according to any one of claims 1 to 7 is mounted in the reactor at the front stage, and the NO _X supply unit and the reducing agent are supplied to one side of the reactor. a section is provided and an outlet section is provided on the other side of the reactor, and
A denitrification device in which an NH ₃ -SCR catalyst is mounted in the latter reactor. Using C ₃ H ₆ as the reducing agent, the residual NO _X concentration monitored by the NO _X concentration monitor provided downstream from the latter reactor, and the NH concentration provided downstream from the latter reactor Based on the residual _{NH3 concentration monitored by the 3 concentration monitor} and the residual _C3H6 concentration monitored by the _{C3H6 concentration} monitor, the _{NH3 yield} and the reducing agent _C3H6 conversion rate 17. The denitrification system _of claim 16, comprising a regulator for adjusting the amount of reducing agent _C3H6 required to produce the desired _NH3 from _NOX by calculating with the correlation data of .

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