WO2020179077A1 - Combustion system - Google Patents

Abstract

Provided is a combustion system using a catalyst with a more satisfactory denitration efficiency at low temperatures during a selective catalytic reduction reaction having ammonia as the reductant, compared to prior art techniques.　The combustion system is equipped with a combustion device for combusting a fuel, an exhaust route for flowing therethrough an exhaust gas generated by the fuel being combusted in the combustion device, a dust collection device disposed in the exhaust route and collecting the soot present in the exhaust gas, and a denitration device disposed in the exhaust route and eliminating nitrogen oxide from the exhaust gas by means of a denitration catalyst. The denitration device is disposed on the downstream side of the dust collection device in the exhaust route. The denitration catalyst has vanadium oxide as the main component. The denitration catalyst has a second metal oxide content of 1% to 40% by weight. In the denitration catalyst, the second metal is at least one metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni, and Fe.

Description

Combustion system

The present invention relates to a combustion system. More specifically, the present invention relates to a combustion system that purifies exhaust gas generated by burning fuel by using a denitration catalyst.

One of the pollutants emitted into the atmosphere by the combustion of fuel, like nitrogen oxides _{(NO, NO 2, NO 3} , N 2 O, N 2 O 3, N 2 O 4, N 2 O 5) is To be Nitrogen oxides cause acid rain, ozone layer depletion, photochemical smog, etc., and have a serious impact on the environment and the human body, so their treatment has become an important issue.

As a technique for removing the above nitrogen oxides, a selective catalytic reduction reaction (NH ₃ —SCR) using ammonia (NH ₃ ) as a reducing agent is known. As described in Patent Document 1, as a catalyst used for the selective catalytic reduction reaction, a catalyst using titanium oxide as a carrier and supporting vanadium oxide is widely used. Titanium oxide is considered to be the best carrier because of its low activity against sulfur oxides and high stability.

On the other hand, although vanadium oxide plays a major role in NH ₃ —SCR, it oxidizes SO ₂ to SO _3, and therefore vanadium oxide could not be supported by about 1 wt% or more. Further, in the conventional NH ₃ -SCR, the catalyst in which vanadium oxide is supported on the titanium oxide carrier hardly reacts at a low temperature, so that the catalyst must be used at a high temperature of 350 to 400°C.
However, in order to increase the degree of freedom in designing the apparatus and equipment for carrying out NH ₃ -SCR and increase the efficiency, it has been required to develop a catalyst that exhibits a high nitrogen oxide reduction rate activity even at low temperatures.

After that, the present inventors have found a denitration catalyst having vanadium pentoxide of 43 wt% or more, a BET specific surface area of 30 m ² /g or more, and used for denitration at 200° C. or lower (Patent Document 2).

Japanese Unexamined Patent Publication No. 2004-275852 Japanese Patent No. 6093101

As a result of diligent studies in an attempt to further improve Patent Document 2, the present inventors have found a denitration catalyst that exhibits a more excellent reduction rate activity of nitrogen oxides.

The object of the present invention is to provide a combustion system using a catalyst that has a better denitration efficiency at low temperature than in the prior art in the selective catalytic reduction reaction using ammonia as a reducing agent.

The present invention provides a combustion device for burning fuel, an exhaust passage through which an exhaust gas generated by combustion of the fuel in the combustion device flows, and a dust collection disposed in the exhaust passage for collecting soot dust in the exhaust gas. A denitration device, which is disposed in the exhaust passage and removes nitrogen oxides from the exhaust gas by a denitration catalyst, wherein the denitration device is a downstream side of the dust collector in the exhaust passage. The denitration catalyst is a denitration catalyst containing vanadium oxide as a main component, the oxide content of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co , W, Mo, Nb, Ce, Sn, Ni, and Fe. The combustion system is a denitration catalyst for at least one metal element selected from the group.

Further, it is preferable that the combustion system further includes an air preheater disposed in the exhaust passage and recovering heat from the exhaust gas, and the air preheater is disposed upstream of the dust collector.

Further, the present invention includes a combustion device that burns fuel, an exhaust passage through which exhaust gas generated by burning the fuel in the combustion device flows, and an air preheater that is arranged in the exhaust passage and recovers heat from the exhaust gas. A combustion system including a denitration device arranged in the exhaust passage and removing nitrogen oxides from the exhaust gas by a denitration catalyst, wherein the denitration device is located downstream of the air preheater in the exhaust passage. The denitration catalyst is a denitration catalyst containing vanadium oxide as a main component, and the oxide content of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co. The present invention relates to a combustion system which is a denitration catalyst of at least one metal element selected from the group consisting of W, Mo, Nb, Ce, Sn, Ni, and Fe.

Further, the present invention comprises an internal combustion engine that burns fuel, an exhaust gas through which exhaust gas generated by combustion of the fuel in the internal combustion engine flows, and exhaust gas that is arranged in the exhaust passage and is discharged from the internal combustion engine. A combustion system including an exhaust heat recovery device that recovers exhaust heat and a denitration device that is arranged in the exhaust passage and removes nitrogen oxides from the exhaust gas by a denitration catalyst. The denitration device is in the exhaust passage. The denitration catalyst, which is arranged on the downstream side of the exhaust heat recovery device, is a denitration catalyst containing vanadium oxide as a main component, and has an oxide content of a second metal of 1 wt% or more and 40 wt% or less. The second metal relates to a combustion system in which the denitration catalyst of at least one metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni, and Fe.

Further, the exhaust heat recovery device includes a turbine device and an exhaust gas economizer, the exhaust gas economizer generates steam by using the exhaust gas discharged from the internal combustion engine and the exhaust gas supplied from the turbine device as a heat source, The turbine device preferably generates power by using the exhaust gas discharged from the internal combustion engine and the steam supplied from the exhaust gas economizer.

The combustion system according to the present invention has a better denitration efficiency at low temperature than in the prior art in the selective catalytic reduction reaction using ammonia as a reducing agent.

It is a graph which shows the NO conversion rate of the vanadium catalyst which does not contain the vanadium catalyst which contains the 2nd metal which concerns on each Example. It is a graph which shows the NO conversion rate of the vanadium catalyst which does not contain the vanadium catalyst which contains cobalt which concerns on each Example. It is a graph which shows the powder XRD pattern of the vanadium catalyst containing cobalt which concerns on each Example and comparative example. It is a graph which shows the Raman spectrum of the vanadium catalyst containing cobalt which concerns on each Example. It is a graph which shows the XPS spectrum in the V2p area|region of the vanadium catalyst containing cobalt which concerns on each Example and a comparative example. It is a graph which shows the XPS spectrum in the Co2p area|region of the vanadium catalyst containing cobalt which concerns on each Example and a comparative example. It is a graph which shows the NO conversion rate of the vanadium catalyst containing tungsten and the vanadium catalyst not containing according to each example. It is a graph which shows the powder XRD pattern of the vanadium catalyst containing tungsten which concerns on each Example and comparative example. It is a graph which shows the ratio of the tungsten element of the vanadium catalyst containing tungsten which concerns on each Example and comparative example. 3 is a graph showing NO conversion rates of vanadium catalyst containing tungsten and vanadium catalyst not containing tungsten according to an example of the present invention. It is a graph which shows the powder XRD pattern of the vanadium catalyst containing tungsten which concerns on each Example and comparative example. It is a graph which shows the ratio of the tungsten element of the vanadium catalyst containing tungsten which concerns on each Example and comparative example. 3 is a graph showing NO conversion rates of vanadium catalyst containing tungsten and vanadium catalyst not containing tungsten according to an example of the present invention. 3 is a graph showing NO conversion rates of a vanadium catalyst containing niobium and a vanadium catalyst not containing niobium according to an example of the present invention. It is a graph which shows the NO conversion rate of the vanadium catalyst containing carbon and cobalt which concerns on the Example of this invention, and the vanadium catalyst which concerns on a comparative example. It is a figure which shows the structure of the combustion system which concerns on the 1st application example of this invention. It is a figure which shows the structure of the combustion system which concerns on the 2nd application example of this invention. It is a figure which shows the structure of the combustion system which concerns on the 3rd application example of this invention. It is a figure which shows the structure of the combustion system which concerns on the 4th application example of this invention.

Hereinafter, the denitration catalyst according to the embodiment of the present invention will be described.

The denitration catalyst of the present invention is a denitration catalyst containing vanadium oxide as a main component, wherein the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co or W. , Mo, Nb, Ce, Sn, Ni, and Fe, at least one metal element selected from the group. Such a denitration catalyst can exhibit a higher denitration effect even in a low temperature environment as compared with a denitration catalyst such as a vanadium / titanium catalyst conventionally used.

First, the denitration catalyst of the present invention contains vanadium oxide as a main component. This vanadium oxide is vanadium (II) oxide (VO), vanadium (III) trioxide (V ₂ O ₃ ), vanadium tetraoxide (IV) (V ₂ O ₄ ), vanadium pentoxide (V) (V ₂ O). ₅ ) is included, and the V element of vanadium pentoxide (V ₂ O ₅ ) may take a pentavalent, tetravalent, trivalent or divalent form during the denitration reaction.
This vanadium oxide is the main component of the denitration catalyst of the present invention, and may contain other substances within the range that does not impair the effects of the present invention. However, in the denitration catalyst of the present invention, vanadium pentoxide conversion It is preferable that the content is 50 wt% or more. More preferably, vanadium oxide is present in the denitration catalyst of the present invention in an amount of 60 wt% or more in terms of vanadium pentoxide.

Secondly, the denitration catalyst of the present invention has a second metal oxide content of 1 wt% or more and 40 wt% or less, but it has been conventionally used by including such a second metal oxide. Compared with denitration catalysts such as vanadium / titanium catalysts, a higher denitration effect can be exhibited even in a low temperature environment. When impurities enter into the denitration catalyst of the present invention, an amorphous part is generated in the denitration catalyst, so that the crystal structure is not continuous, and the lines and planes in the crystal lattice are distorted, thereby exhibiting a high denitration effect. However, it is presumed that the higher the amount of the oxide of the second metal as the impurity, the higher the denitration effect will be exhibited.

In the embodiment of the present invention, in the selective catalytic reduction reaction at a reaction temperature of 200° C. or lower using a denitration catalyst having a cobalt oxide content of 1 wt% to 10 wt% as the second metal oxide, the coexistence of water is present. When it was not below, the NO conversion rate was 79% to 100%, and when it was in the presence of water, the NO conversion rate was 38% to 90%.
On the other hand, in the selective catalytic reduction reaction at 200° C. or lower using a denitration catalyst having a cobalt oxide content of 0 wt% as the oxide of the second metal, the NO conversion rate of 76% was obtained in the absence of water. However, only 32% NO conversion was shown in the presence of water.

In a selective catalytic reduction reaction at a reaction temperature of 200° C. or less using a denitration catalyst having a tungsten oxide content of 12 wt% to 38 wt% as an oxide of the second metal, it is possible to obtain 83 % NO conversion of 96% and 96% NO conversion of 50% to 55% in the presence of water.
On the other hand, in the selective catalytic reduction reaction at 200° C. or lower using a denitration catalyst having a tungsten oxide content of 0 wt% as the oxide of the second metal, the NO conversion rate of 76% was obtained in the absence of water. However, only 32% NO conversion was shown in the presence of water.
Further, in a selective catalytic reduction reaction at 200° C. or lower using a denitration catalyst having a tungsten oxide content of 62 wt% to 100 wt% as an oxide of the second metal, it is 3 to 69 in the absence of water. % NO conversion, only 0% to 29% NO conversion in the presence of water.

Further, in a selective catalytic reduction reaction using a denitration catalyst having a niobium oxide content of 2 wt% to 16 wt% as an oxide of the second metal, NO conversion of 76 wt% to 97% was performed in the absence of water. %, the NO conversion rate of 32% to 73% was shown in the case of coexistence of water.

Further, in the above description, the denitration catalyst of the present invention has the second metal oxide content of 1 wt% or more and 40 wt% or less, but it is preferably 3 wt% or more and 38 wt% or less. Further, the content of the oxide of the second metal is more preferably 3 wt% or more and 10 wt% or less. Further, the content of the oxide of the second metal is more preferably 5 wt% or more and 10 wt% or less. Further, the content of the oxide of the second metal is more preferably 5 wt% or more and 8 wt% or less. The oxide content of the second metal is more preferably 6 wt% or more and 8 wt% or less. Further, the content of the oxide of the second metal is more preferably 6 wt% or more and 7 wt% or less.

Thirdly, the second metal is at least one metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni and Fe. Thereby, the crystal structure of vanadium oxide is disturbed, and Lewis acidity can be enhanced. In particular, in the case of Co, Mo, Ce, Sn, Ni, and Fe, it accelerates the redox cycle of V ₂ O ₅ . In addition, among these elements, Co is known to have a strong oxidizing power. Each of W, Mo, and Nb functions as a solid acid and provides an adsorption site for ammonia, so that ammonia can efficiently contact and react with NO.

In the embodiment of the present invention, in a selective catalytic reduction reaction at a reaction temperature of 200° C. or lower using a denitration catalyst having a cobalt oxide content of 3.1 wt% as the second metal oxide, coexistence of water is performed. When it was not, the NO conversion rate was 94.6%, and when it was not, the NO conversion rate was 69.4% in the presence of water.
Further, in the embodiment of the present invention, in the selective catalytic reduction reaction at a reaction temperature of 200° C. or less using a denitration catalyst having a tungsten oxide content of 8.4 wt% as the second metal oxide, The NO conversion rate was 92% in the absence of coexistence, and the NO conversion rate of 64% in the presence of water.
Further, in the embodiment of the present invention, in the selective catalytic reduction reaction at a reaction temperature of 200° C. or less using a denitration catalyst having a molybdenum oxide content of 5.4 wt% as the second metal oxide, The NO conversion rate of 97% was shown without coexistence, and the NO conversion rate of 62% was shown without water coexistence.
Further, in the embodiment of the present invention, in the selective catalytic reduction reaction at a reaction temperature of 200 ° C. or lower using a denitration catalyst having a niobium pentoxide content of 5.0 wt% as the oxide of the second metal, the water content is reduced. The NO conversion rate of 96.7% was shown when not coexisting, and the NO conversion rate was 61.7% when not coexisting with water.
Further, in the embodiment of the present invention, in the selective catalytic reduction reaction at a reaction temperature of 200° C. or lower using a denitration catalyst having a cesium oxide content of 6.4 wt% as the second metal oxide, The NO conversion rate of 89.8% was shown when not coexisting, and the NO conversion rate was 52.9% when not coexisting with water.
Further, in the embodiment of the present invention, in the selective catalytic reduction reaction at a reaction temperature of 200° C. or lower using a denitration catalyst having a tin oxide content of 5.6 wt% as the second metal oxide, The NO conversion rate was 88.1% when not coexisting, and the NO conversion rate was 45.5% when water was coexisting.
In addition, in the embodiment of the present invention, in the selective catalytic reduction reaction at a reaction temperature of 200° C. or less using a denitration catalyst having a nickel oxide content of 2.9 wt% as the second metal oxide, The NO conversion rate of 81.9% was shown when not coexisting, and the NO conversion rate was 37.9% when not coexisting with water.
In addition, in the embodiment of the present invention, in the selective catalytic reduction reaction at a reaction temperature of 200° C. or less using a denitration catalyst having an iron oxide content of 3.1 wt% as the second metal oxide, The NO conversion rate of 74.5% was shown when not coexisting, and the NO conversion rate was 33.9% when not coexisting with water.
On the other hand, in the selective catalytic reduction reaction at 200° C. or lower using the denitration catalyst containing no second metal oxide, the NO conversion rate of 75.5% was obtained in the presence of water in the absence of water. In this case, only 32% NO conversion rate was shown.

Further, the denitration catalyst of the present invention is preferably used for denitration at 300°C or lower. This is because the denitration catalyst of the present invention has a firing temperature of 300°C. On the other hand, in the examples described below, the denitration catalyst of the present invention exerted a high denitration effect in the selective catalytic reduction reaction at a reaction temperature of 200° C. or lower, so that the denitration catalyst of the present invention It can be used for denitration. Since oxidation of SO ₂ to SO ₃ does not occur at 200° C. or lower, as is also found in Patent Document 2 described above, during selective catalytic reduction reaction, oxidation of SO ₂ to SO ₃ is not accompanied.

Further, in the above description, the denitration catalyst of the present invention is preferably used for denitration at 300° C. or lower, but may be preferably used for denitration at 200° C. or lower, more preferably, the reaction temperature is It may be used for denitration at 100 to 200°C. More preferably, it may be used for denitration at a reaction temperature of 160-200 ° C. Alternatively, it may be used for denitration with a reaction temperature of 80-150 ° C.

Further, the denitration catalyst of the present invention preferably further contains carbon. Particularly, the carbon content is preferably 0.05 wt% or more. In addition, preferably, the carbon content may be 0.07 wt% or more. More preferably, the carbon content may be 0.11 wt% or more. More preferably, the carbon content may be 0.12 wt% or more. More preferably, the carbon content may be 0.14 wt% or more. More preferably, the carbon content may be 0.16 wt% or more. More preferably, the carbon content may be 0.17 wt% or more. More preferably, the carbon content may be 0.70 wt% or more.
By containing carbon, a higher denitration effect can be exhibited even in a low temperature environment as compared with the conventionally used denitration catalysts such as vanadium / titanium catalysts. When impurities enter into the denitration catalyst of the present invention, an amorphous part is generated in the denitration catalyst, so that the crystal structure is not continuous, and the lines and planes in the crystal lattice are distorted, thereby exhibiting a high denitration effect. However, it is speculated that the presence of carbon as an impurity exerts a high denitration effect.

Hereinafter, a denitration catalyst containing vanadium oxide as a main component, wherein the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co, W, Mo, Nb, A method for producing a denitration catalyst that is at least one metal element selected from the group consisting of Ce, Sn, Ni, and Fe will be described.

The above method for producing a denitration catalyst includes a step of calcining a mixture of vanadate, a chelate compound, and a compound of a second metal.
As the vanadate, for example, ammonium vanadate, magnesium vanadate, strontium vanadate, barium vanadate, zinc vanadate, lead vanadate, lithium vanadate, etc. may be used.
Examples of the chelate compound include those having a plurality of carboxyl groups such as oxalic acid and citric acid, those having a plurality of amino groups such as acetylacetonate and ethylenediamine, and those having a plurality of hydroxyl groups such as ethylene glycol. Etc. may be used.
The compound of the second metal may be a chelate complex, a hydrate, an ammonium compound or a phosphoric acid compound. The chelate complex may be, for example, a complex such as oxalic acid or citric acid. The hydrate, for example, _{(NH 4)} may be _{10 W 12 O 41 · 5H 2} O and _{H 3 PW 12 O 40 · nH} 2 O. The ammonium compound, for example, _{(NH 4)} may be _{10 W 12 O 41 · 5H 2} O. Examples of the phosphoric acid compound may be, for example, _{H 3 PW 12 O 40 · nH} 2 O.

Further, it is preferable that the above mixture further contains ethylene glycol.

The denitration catalyst produced by these methods can exhibit a high denitration effect even in a low temperature environment as compared with denitration catalysts such as vanadium/titanium catalysts that have been conventionally used. When impurities enter into the denitration catalyst of the present invention, an amorphous part is generated in the denitration catalyst, so that the crystal structure is not continuous, and the lines and planes in the crystal lattice are distorted, thereby exhibiting a high denitration effect. However, it is presumed that the more carbon as an impurity is present, the higher the denitration effect is exhibited.

In an embodiment of the present invention, the denitration catalyst prepared by the method of calcining a mixture of ammonium vanadate, oxalic acid, and an oxalic acid complex of a second metal has a denitration rate of 74.5 to 100% in the absence of water. The NO conversion was 33.9 to 90% in the presence of water.
In addition, the denitration catalyst produced by the method in which the above mixture further contains ethylene glycol has a NO conversion rate of 100% in the absence of water and an NO conversion rate of 89% in the presence of water. Indicated.
On the other hand, as a denitration catalyst manufactured by a method not including such a step, for example, ammonium vanadate and oxalic acid are mixed, but a method of firing without mixing the oxide of the second metal is used. The denitration catalyst thus obtained showed a NO conversion of 76% in the absence of water and a NO conversion of 32% in the presence of water.

Further, the above-mentioned firing is preferably performed at a temperature of 270° C. or lower.
When the denitration catalyst according to the present embodiment is produced, the structure of the vanadium pentoxide crystal contained in the denitration catalyst is locally disordered by firing at a temperature of 270° C. or lower, which is lower than the normal 300° C., Although a high denitration effect can be exerted, it is speculated that a high denitration effect is exerted particularly by the appearance of sites lacking oxygen atoms in the crystal structure of vanadium pentoxide. Note that the “site devoid of oxygen atoms” is also referred to as “oxygen defect site”.

The denitration catalyst prepared in this manner is a denitration catalyst containing vanadium oxide as a main component, wherein the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, and the second metal Is at least one metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni, and Fe.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within the scope of achieving the object of the present invention are included in the present invention.

Hereinafter, examples of the present invention will be specifically described with comparative examples. The present invention is not limited to these examples.

<1 Vanadium catalyst containing various metals as second metal>
<1.1 Examples and Comparative Examples>

[Example 1]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. With respect to this precursor complex, a oxalic acid complex of cobalt (Co), which is a second metal, is added so that cobalt (Co) is 3.5 mol% in terms of metal atom, that is, Co ₃ O in terms of metal oxide. ₄ was added so as to be 3.1 wt %. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace heterogeneous metal complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ) ..

[Example 2]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. With respect to this precursor complex, the oxalic acid complex of tungsten (W), which is the second metal, is added so that the tungsten (W) is 3.5 mol% in terms of metal atom, that is, WO ₃ is converted into metal oxide. It was added so as to be 8.4 wt%. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace heterogeneous metal complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing tungsten _{(W) (V 2 O 5} ) ..

[Example 3]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. With respect to this precursor complex, the oxalic acid complex of molybdenum (Mo), which is the second metal, has molybdenum (Mo) of 3.5 mol% in terms of metal atoms, that is, MoO _{3 in} terms of metal oxides. It was added so as to be 5.4 wt%. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace heterogeneous metal complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing molybdenum _{(Mo) (V 2 O 5} ) ..

[Example 4]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. An oxalic acid complex of niobium (Nb), which is the second metal, is added to the precursor complex so that niobium (Nb) is 3.5 mol% in terms of metal atom, that is, Nb ₂ O in terms of metal oxide. ₅ was added so as to be 5.0 wt%. The obtained vanadium-different metal complex mixture was baked twice in an electric furnace at a temperature of 300° C. for 4 hours to obtain a vanadium pentoxide (V ₂ O ₅ ) denitration catalyst containing niobium (Nb). ..

[Example 5]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. With respect to this precursor complex, an oxalic acid complex of cesium (Ce), which is the second metal, was added so that cesium (Ce) would be 3.5 mol% in terms of metal atom, that is, CeO _{2 in} terms of metal oxide. It was added so as to be 6.4 wt%. The vanadium-dissimilar metal complex mixture thus obtained was calcined twice in an electric furnace at a temperature of 300° C. for 4 hours to obtain a vanadium pentoxide (V ₂ O ₅ ) denitration catalyst containing cesium (Ce). ..

[Example 6]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. The oxalic acid complex of the second metal tin (Sn) is added to the precursor complex so that tin (Sn) is 3.5 mol% in terms of metal atom, that is, SnO ₂ is in terms of metal oxide. It was added so as to be 5.6 wt%. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace heterogeneous metal complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing tin _{(Sn) (V 2 O 5} ) ..

[Example 7]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. With respect to this precursor complex, 0.113 g of nickel (Ni) as a second metal as nickel carbonate and 3.5 mol% of nickel (Ni) in terms of metal atoms, that is, NiO in terms of metal oxides. Was added so as to be 2.9 wt %. The vanadium-different metal complex mixture thus obtained was calcined twice in an electric furnace at a temperature of 300° C. for 4 hours to obtain a vanadium pentoxide (V ₂ O ₅ ) denitration catalyst containing nickel (Ni). ..

[Example 8]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. With respect to this precursor complex, the oxalic acid complex of iron (Fe), which is the second metal, is added so that iron (Fe) is 3.5 mol% in terms of metal atom, that is, Fe ₂ O in terms of metal oxide. ₃ was added so as to be 3.1 wt %. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace heterogeneous metal complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing iron _{(Fe) (V 2 O 5} ) ..

[Comparative Example 1]
4.96 g (42.4 mmol) of ammonium vanadate (NH ₄ VO ₃ ) and 11.5 g (127.6 mmol) of oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. 4 hours at a temperature of 300 ° C. The precursor complex by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing no second metal (V 2 _{O 5).}

<1.2 Evaluation>
<1.2.1 NO conversion rate>
Under the conditions shown in Table 1 below, the NH _3- SCR reaction was carried out at a reaction temperature of 150 ° C. using a fixed bed flow type catalytic reactor. Of the gas that passed through the catalyst layer, NO was analyzed by Jasco FT-IR-4700.

Further, the NO conversion rate was calculated by the following formula (1). Note that NO _in is the NO concentration at the reaction tube inlet, and NO _out is the NO concentration at the reaction tube outlet.

(Measurement result)
Table 2 shows the NO conversion rates of each vanadium pentoxide catalyst in both the case where water does not coexist and the case where water coexists. FIG. 1 is a graph of this Table 2.

In both the case where water did not coexist and the case where water coexisted, the denitration catalyst of the example generally showed a higher NO conversion rate than the denitration catalyst of the comparative example. In particular, the denitration catalyst obtained by adding cobalt, tungsten, molybdenum, and niobium to ammonium vanadate and firing showed a high NO conversion rate. Above all, in the case where water does not coexist, Example 3 (adding molybdenum) and in the case where water coexists, Example 1 (adding cobalt) showed the highest NO conversion rate.

<2 Vanadium catalyst containing cobalt as second metal>
<2.1 Examples>

As described above, in the vanadium catalysts of Examples 1 to 8, when water coexists, Example 1 (adding cobalt) showed the highest NO conversion rate, so the amount of cobalt added was changed. As a result, vanadium catalysts according to the following examples were produced.

[Example 9]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. An oxalic acid complex of the second metal, cobalt (Co), was added to this precursor complex such that Co ₃ O ₄ was 1 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. The cobalt complex mixture by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ).

[Example 10]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. An oxalic acid complex of cobalt (Co), which is the second metal, was added to this precursor complex such that Co ₃ O ₄ was 3 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. The cobalt complex mixture by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ).

[Example 11]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. An oxalic acid complex of cobalt (Co), which is the second metal, was added to this precursor complex such that Co ₃ O ₄ was 5 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. The cobalt complex mixture by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ).

[Example 12]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. To this precursor complex, an oxalic acid complex of the second metal, cobalt (Co), was added so that Co ₃ O ₄ was 6 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. The cobalt complex mixture by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ).

[Example 13]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. An oxalic acid complex of the second metal, cobalt (Co), was added to this precursor complex such that Co ₃ O ₄ was 7 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. The cobalt complex mixture by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ).

[Example 14]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. An oxalic acid complex of the second metal, cobalt (Co), was added to this precursor complex so that Co ₃ O ₄ was 8 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. The cobalt complex mixture by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ).

[Example 15]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. To this precursor complex, a oxalic acid complex which is a precursor of cobalt (Co), which is a second metal, was added so that Co ₃ O ₄ was 10 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. The cobalt complex mixture by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ).

In addition, Table 3 below shows the charged amount of the precursor in Example 9 to Example 15 when cobalt was introduced.

<2.2 Evaluation>
<2.2.1 NO conversion rate>
(Measuring method)
Under the conditions shown in Table 1 above, the NH _3- SCR reaction was carried out at a reaction temperature of 150 ° C. using a fixed-bed flow catalytic reactor. Of the gas that passed through the catalyst layer, NO was analyzed by Jasco FT-IR-4700.
Further, the NO conversion rate was calculated by the above equation (1).

(Measurement result)
Table 4 shows the NO conversion of each vanadium oxide catalyst both in the absence of water and in the presence of water. FIG. 2 is a graph of this Table 4.

The denitration catalysts of the examples all showed higher NO conversion than the denitration catalysts of the comparative examples both in the absence of water and in the presence of water. Particularly, in the case where water does not coexist, Example 12 (6 wt%) and Example 13 (7 wt%) show the highest NO conversion, and in the case where water coexists, Example 14 (8 wt%). The highest NO conversion was shown.

<2.2.2 Powder X-ray diffraction>
(Diffraction method)
As the powder X-ray diffraction, a measurement was performed using Cu—Kα by Rigaku smart lab.

(Diffraction result)
FIG. 3 shows powder XRD of Example 9 (1 wt %), Example 10 (3 wt %), Example 12 (6 wt %), Example 15 (10 wt %), and Comparative Example 1 (None: 0 wt %). X-Ray Diffraction) pattern is shown.
It was shown that V ₂ O _5, which is a stable phase, is present as a main component, and that when the addition rate of Co is increased, a Co ₃ O ₄ phase also appears.

<2.2.3 Raman spectrum>
(Measuring method)
Raman spectra were measured by Raman spectroscopy to analyze the crystal structure of each vanadium pentoxide catalyst. More specifically, a small amount of each catalyst sample was placed on a slide glass, and the Raman spectrum was measured by a Raman spectroscope. A NRS-4100 Raman spectrophotometer manufactured by JASCO Corporation was used as a measuring instrument.

(Measurement result)
FIG. 4 shows the Raman spectrum of each catalyst. It was shown that when the amount of Co added was increased, the crystal structure of V ₂ O ₅ collapsed and the pattern strength weakened.

<2.2.4 X-ray photoelectron spectrum (XPS) measurement>
(Measuring method)
To analyze the electronic state of Example 9 (1 wt%), Example 10 (3 wt%), Example 12 (6 wt%), Example 15 (10 wt%), and Comparative Example 1 (None: 0 wt%). , X-ray photoelectron spectrum (XPS: X-Ray Photoelectron Spectrom) was measured. More specifically, powder samples of the catalysts of Examples and Comparative Examples were fixed to a sample holder using a carbon tape, and X-ray photoelectron spectra were measured. As a measuring device, a JPS-9010MX photoelectron spectrometer manufactured by JEOL Ltd. was used.

(Measurement result)
FIG. 5A shows an XPS spectrum in the V2p region. FIG. 5B shows an XPS spectrum in the Co2p region. It was shown that increasing the added amount of Co increased the V ⁴⁺ and Co ²⁺ components.

<3 Vanadium catalyst containing tungsten as second metal>
<3.1 Examples>
As described above, in the vanadium catalysts of Examples 1 to 8, in the case where water coexists, Example 2 (adding tungsten) showed the second highest NO conversion rate, so the amount of tungsten added was changed. By doing so, a vanadium catalyst according to each of the following examples was produced. It should be noted that not only the amount of tungsten added is changed, but also when K ₂ WO ₄ is used as the precursor and when H ₃ PW ₁₂ O ₄₀ · nH ₂ O is used as a precursor, tungsten is used as described later. The amount added was changed.

[Example 16]
To a mixture of ammonium vanadate (NH ₄ VO ₃ ), 43.9 mmol of K ₂ WO ₄ and 20 ml of pure water, 11.9 g (131.7 mmol) of oxalic acid ((COOH) ₂ ) was added, and the mixture was cooled to room temperature. After stirring for 10 minutes at 70° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. The amount of ammonium vanadate as a raw material was adjusted so that the total weight ratio of WO _{3 in} the produced denitration catalyst was 4.9 wt%.

[Example 17]
To a mixture of ammonium vanadate (NH ₄ VO ₃ ), 43.9 mmol of K ₂ WO ₄ and 20 ml of pure water, 11.9 g (131.7 mmol) of oxalic acid ((COOH) ₂ ) was added, and the mixture was cooled to room temperature. After stirring for 10 minutes at 70° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. The amount of ammonium vanadate as a raw material was adjusted so that the total weight ratio of WO _{3 in} the produced denitration catalyst was 11.8 wt %.

[Example 18]
11.9 g (131.7 mmol) of oxalic acid was added to a mixture of ammonium vanadate (NH ₄ VO ₃ ), 43.9 mmol of K ₂ WO ₄ and 20 ml of pure water, and the mixture was stirred at room temperature for 10 minutes. , 70 ° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. The amount of ammonium vanadate as a raw material was adjusted so that the total weight ratio of WO _{3 in} the produced denitration catalyst was 22.1 wt%.

[Comparative Example 2]
To a mixture of ammonium vanadate (NH ₄ VO ₃ ), 43.9 mmol of K ₂ WO ₄ and 20 ml of pure water, 11.9 g (131.7 mmol) of oxalic acid ((COOH) ₂ ) was added, and the mixture was cooled to room temperature. After stirring for 10 minutes at 70° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. The amount of ammonium vanadate as a raw material was adjusted so that the total weight ratio of WO _{3 in} the produced denitration catalyst was approximately 100 wt%.

In addition, Table 5 below shows the amount of the precursor charged at the time of introducing tungsten in Examples 16 to 18 and Comparative Example 2.

[Example 19]
Ammonium vanadate _(NH 4 _{VO 3),} and _{H 3 PW 12 O 40 · nH} 2 O, a mixture of pure water 20 ml, oxalic acid _{((COOH) 2)} a 11.9g (131.7mmol) was added The mixture was stirred at room temperature for 10 minutes and then at 70° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. Incidentally, the total weight ratio of WO ₃ in the denitration catalyst to be generated, so that the 38.4Wt%, and adjust the amount of ammonium vanadate and _{H 3 PW 12 O 40 · nH} 2 O as raw materials.

[Comparative Example 3]
Ammonium vanadate _(NH 4 _{VO 3),} and _{H 3 PW 12 O 40 · nH} 2 O, a mixture of pure water 20 ml, oxalic acid _{((COOH) 2)} a 11.9g (131.7mmol) was added The mixture was stirred at room temperature for 10 minutes and then at 70° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. Incidentally, the total weight ratio of WO ₃ in the denitration catalyst to be generated, so that the 61.7Wt%, and adjust the amount of ammonium vanadate and _{H 3 PW 12 O 40 · nH} 2 O as raw materials.

[Comparative Example 4]
Ammonium vanadate _(NH 4 _{VO 3),} and _{H 3 PW 12 O 40 · nH} 2 O, a mixture of pure water 20 ml, oxalic acid _{((COOH) 2)} a 11.9g (131.7mmol) was added The mixture was stirred at room temperature for 10 minutes and then at 70° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. Incidentally, the total weight ratio of WO ₃ in the denitration catalyst to be generated, so that the 77.3Wt%, and adjust the amount of ammonium vanadate and _{H 3 PW 12 O 40 · nH} 2 O as raw materials.

[Comparative Example 5]
Ammonium vanadate _(NH 4 _{VO 3),} and _{H 3 PW 12 O 40 · nH} 2 O, a mixture of pure water 20 ml, oxalic acid _{((COOH) 2)} a 11.9g (131.7mmol) was added The mixture was stirred at room temperature for 10 minutes and then at 70° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. The amounts of ammonium vanadate and H ₃ PW ₁₂ O ₄₀ .nH ₂ O as raw materials were adjusted so that the total weight ratio of WO _{3 in} the produced denitration catalyst was 84.4 wt %.

[Comparative Example 6]
Ammonium vanadate _(NH 4 _{VO 3),} and _{H 3 PW 12 O 40 · nH} 2 O, a mixture of pure water 20 ml, oxalic acid _{((COOH) 2)} a 11.9g (131.7mmol) was added The mixture was stirred at room temperature for 10 minutes and then at 70° C. for 12 hours. By firing this precursor sample at 300° C. for 4 hours, a denitration catalyst of vanadium pentoxide (V ₂ O ₅ ) containing tungsten (W) was obtained. Incidentally, the total weight ratio of WO ₃ in the denitration catalyst to be generated, so as to be substantially 100 wt%, and adjust the amount of ammonium vanadate and _{H 3 PW 12 O 40 · nH} 2 O as raw materials.

In addition, Table 6 below shows the amount of precursor charged at the time of introducing tungsten in Example 19 and Comparative Examples 3 to 6.

<3.2 Evaluation>
<3.2.1 Outline>
Under the conditions shown in Table 1 above, the NH _3- SCR reaction was carried out at a reaction temperature of approximately 150 ° C. using a fixed bed flow type catalytic reaction apparatus. Of the gas that passed through the catalyst layer, NO was analyzed by Jasco FT-IR-4700.
Further, the NO conversion rate was calculated by the above equation (1).

(Measurement result)
Table 7 shows the NO conversion rates of each vanadium pentoxide catalyst in both the case where water does not coexist and the case where water coexists. FIG. 6 is a graph of Table 7.

Comparing with Comparative Example 1 having a tungsten content of 0 wt% and Comparative Examples 2-5 and 7 having a tungsten content of 39 wt% to 100 wt% both in the case where water does not coexist and in the case where water coexists. In general, it has been shown that the addition amount of tungsten between 10 and 38 wt% is effective.

Hereinafter, elemental analysis by powder X-ray diffraction and SEM-EDS is performed for each of the case of using K ₂ WO ₄ and the case of using H ₃ PW ₁₂ O ₄₀ .nH ₂ O as precursors, and In the case, the NO conversion rate for each tungsten content rate was graphed.

<3.2.2 When K ₂ WO ₄ is used as a precursor>
<3.2.2.1 Powder X-ray diffraction and elemental analysis>
(Measuring method)
As the powder X-ray diffraction, a measurement was performed using Cu—Kα by Rigaku smart lab. In addition, elemental analysis by SEM-EDS was performed.

(Measurement result)
FIG. 7 shows Example 16 (4.9 wt %), Example 17 (11.8 wt %), Example 18 (22.1 wt %), Comparative Example 1 (0 wt %), and Comparative Example 2 (100 wt %). 3 shows a powder XRD pattern.
In addition, FIG. 8 shows the percentage (%) of the tungsten element when the horizontal axis represents mol% of K ₂ WO ₄ .

From FIGS. 7 and 8, by increasing K ₂ WO ₄ , the crystal phase changed from triclinic V ₄ O ₇ (12 wt%) to monoclinic WO ₃ (100 wt%), and the catalyst. It was shown that the ratio of the tungsten atoms contained in was proportionally increased.

<3.2.2.2 NO conversion rate>
(Measurement result)
Table 8 shows the NO conversion rates of each vanadium pentoxide catalyst in both the case where water does not coexist and the case where water coexists. FIG. 9 is a graph of this Table 6.

As can be seen from Table 8 and FIG. 9, the catalytic activity was maximized (96.3%) in the triclinic V ₄ O ₇ (22.1 wt%). In addition, excess K ₂ WO ₄ caused a decrease in catalytic activity, and when the tungsten content was 100 wt%, there was no catalytic activity.

<3.2.3 using _{H 3 PW 12 O 40 · nH} 2 O as precursors>
<3.2.3.1 Powder X-ray diffraction and elemental analysis>
(Measuring method)
As the powder X-ray diffraction, a measurement was performed using Cu—Kα by Rigaku smart lab. In addition, elemental analysis by SEM-EDS was performed.

(Measurement result)
FIG. 10 shows Example 19 (38.4 wt %), Comparative Example 4 (61.7 wt %), Comparative Example 5 (77.3 wt %), Comparative Example 6 (84.4 wt %), Comparative Example 7 (100 wt %). ) Is shown in the powder XRD pattern.
Further, FIG. 11 shows the proportion (%) of the tungsten element when the horizontal axis is mol% of H ₃ PW ₁₂ O ₄₀ · nH ₂ O.

10 and _11, of _{H 3 PW 12 O 40 · nH} 2 O charged amounts by increasing _{the, H 3 PW 12 O 40 ·} nH 2 to O diffraction peak derived from increases, and relatively small amounts of It was shown that the content of tungsten increased with the charged amount.

<3.2.3.2 NO conversion rate>
(Measurement result)
Table 9 shows the NO conversion rates of each vanadium pentoxide catalyst in both the case where water does not coexist and the case where water coexists. FIG. 12 is a graph of this Table 9.

As can be seen from Table 9 and FIG. 12, when H ₃ PW ₁₂ O ₄₀ .nH ₂ O is used as the precursor, the maximum catalytic activity (82.9%) is obtained when the tungsten content is 38.4 wt %. and _although, the K 2 WO ₄ and the precursor, the content of tungsten towards 22.1Wt% vanadium catalyst was higher results catalytic activity.

<4 Vanadium catalyst containing niobium as the second metal>
<4.1 Examples>

As described above, in the vanadium catalysts of Examples 1 to 8, when water does not coexist, Example 4 (with niobium added) shows the second highest NO conversion rate, and water coexists. However, since the NO conversion was relatively high, the vanadium catalyst according to each of the following examples was produced by changing the addition amount of niobium.

[Example 20]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. To this precursor complex, a oxalic acid complex of niobium (Nb), which is a second metal, was added so that Nb ₂ O ₅ was 1.8 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace niobium complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing niobium _{(Nb) (V 2 O 5} ).

[Example 21]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. To this precursor complex, a oxalic acid complex of niobium (Nb), which is a second metal, was added so that Nb ₂ O ₅ was 5.2 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace niobium complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing niobium _{(Nb) (V 2 O 5} ).

[Example 22]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. To this precursor complex, a oxalic acid complex of niobium (Nb), which is a second metal, was added so that Nb ₂ O ₅ was 8.5 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. The cobalt complex mixture by an electric furnace and fired twice to obtain a denitration catalyst of vanadium pentoxide containing cobalt _{(Co) (V 2 O 5} ).

[Example 23]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. To this precursor complex, a oxalic acid complex of niobium (Nb), which is a second metal, was added so that Nb ₂ O ₅ was 11.7 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace niobium complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing niobium _{(Nb) (V 2 O 5} ).

[Example 24]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid ((COOH) ₂ ) were dissolved in pure water to synthesize a precursor complex. To this precursor complex, a oxalic acid complex of niobium (Nb), which is a second metal, was added so that Nb ₂ O ₅ was 16.2 wt% in terms of metal oxide. The resulting vanadium - 4 hours at a temperature of 300 ° C. by an electric furnace niobium complex mixture, by firing twice, to obtain a denitration catalyst of vanadium pentoxide containing niobium _{(Nb) (V 2 O 5} ).

In addition, Table 10 below shows the amount of the precursor charged at the time of introducing niobium in Examples 20 to 24.

<4.2 Evaluation>
<4.2.1 NO conversion>
(Measuring method)
Under the conditions shown in Table 1 above, the NH _3- SCR reaction was carried out at a reaction temperature of 150 ° C. using a fixed-bed flow catalytic reactor. Of the gas that passed through the catalyst layer, NO was analyzed by Jasco FT-IR-4700.
Further, the NO conversion rate was calculated by the above equation (1).

(Measurement result)
Table 11 shows the NO conversion of each vanadium oxide catalyst both in the absence of water and in the presence of water. FIG. 13 is a graph of this table 11.

The denitration catalysts of the examples all showed higher NO conversion than the denitration catalysts of the comparative examples both in the absence of water and in the presence of water. In particular, in the absence of water, Example 22 (9 wt%) showed the highest NO conversion, and in the presence of water, Example 21 (5 wt%) showed the highest NO conversion. ..

<Vanadium catalyst containing 5 carbon and cobalt as a second metal and calcined at low temperature>
<5.1 Examples and Comparative Examples>
[Example 25]
Ammonium vanadate (NH ₄ VO ₃ ) and oxalic acid were dissolved in pure water to synthesize a precursor complex. To this precursor complex, ethylene glycol and an oxalic acid complex which is a precursor of cobalt (Co) which is the second metal were added so that Co ₃ O ₄ was 6 wt% in terms of metal oxide. The obtained catalyst skeleton was fired in an electric furnace at a temperature of 270° C. for 2 hours to obtain a vanadium oxide denitration catalyst containing carbon and cobalt (Co).
In addition, Table 12 below shows the charged amount of the precursor when cobalt was introduced in Example 25.

<5.2 Evaluation>
<5.2.1 Carbon content>
(Measuring method)
When measuring the carbon content of each vanadium pentoxide catalyst, the carbon content was quantified by elemental analysis of C (carbon), H (hydrogen), and N (nitrogen). More specifically, each denitration catalyst is completely combusted and decomposed in a high-temperature reaction tube inside the CE-440F manufactured by Exeter Analytical Co., and C, H, and N, which are main constituent elements, are CO ₂ , H ₂ O, After conversion to N ₂ , these three components were sequentially quantified by three thermal conductivity detectors, and the contents of C, H, and N in the constituent elements were measured.

(Measurement result)
The carbon content of the vanadium catalyst of Example 25 was 0.70 wt %.

<5.22 NO conversion rate>
(Measuring method)
Under the conditions shown in Table 1 above, the NH _3- SCR reaction was carried out at a reaction temperature of 150 ° C. using a fixed-bed flow catalytic reactor. Of the gas that passed through the catalyst layer, NO was analyzed by Jasco FT-IR-4700.
Further, the NO conversion rate was calculated by the above equation (1).

(Measurement result)
Table 13 shows the NO conversion rates of the vanadium pentoxide catalysts of Comparative Example 1, Example 12, and Example 25 in both the case where water does not coexist and the case where water coexists. FIG. 14 is a graph of this table 13.

The denitration catalyst of Example 25 showed the highest NO conversion rate both in the absence of water and in the presence of water.

<6 application example>
<6.1 Combustion system>
<6.1.1 First combustion system>
Hereinafter, the first application example of the present invention will be described with reference to the drawings.
FIG. 15: is a figure which shows the structure of the combustion system 1 which concerns on a 1st application example. The combustion system 1 is a combustion system using pulverized coal as fuel. As shown in FIG. 15, the combustion system 1 is assumed to be a thermal power generation system as an example, and includes a boiler 10 as a combustion device, a pulverized coal machine 20, an exhaust passage L1, an air preheater 30, and heat recovery. A gas heater 40 as a vessel, a dust collector 50, an induced draft fan 60, a desulfurization apparatus 70, a gas heater 80 as a heater, a denitration apparatus 90, and a chimney 100 are provided.

The boiler 10 burns pulverized coal as fuel with air. Exhaust gas is generated by burning pulverized coal in the boiler 10. The combustion of pulverized coal produces coal ash such as clinker ash and fly ash. The clinker ash generated in the boiler 10 is discharged to the clinker hopper 11 arranged below the boiler 10 and then conveyed to a coal ash recovery silo (not shown).

The boiler 10 is formed in a substantially inverted U shape as a whole. The exhaust gas generated in the boiler 10 moves in an inverted U shape along the shape of the boiler 10. The temperature of the exhaust gas in the vicinity of the exhaust gas outlet of the boiler 10 is, for example, 300 to 400°C.

The pulverized coal machine 20 pulverizes coal supplied from a coal bunker (not shown) to a fine particle size to form pulverized coal. The pulverized coal machine 20 preheats and dries the pulverized coal by mixing the pulverized coal and air. The pulverized coal formed in the pulverized coal machine 20 is supplied to the boiler 10 by blowing air.

The upstream side of the exhaust passage L1 is connected to the boiler 10. The exhaust passage L1 is a passage through which exhaust gas generated in the boiler 10 flows.

The air preheater 30 is arranged in the exhaust path L1. The air preheater 30 performs heat exchange between the exhaust gas and the combustion air sent from a push-type fan (not shown) to recover heat from the exhaust gas. The combustion air is heated in the air preheater 30 and then supplied to the boiler 10.

The gas heater 40 is arranged downstream of the air preheater 30 in the exhaust passage L1. The gas heater 40 is supplied with the exhaust gas whose heat is recovered in the air preheater 30. The gas heater 40 further recovers heat from the exhaust gas.

The dust collector 50 is arranged on the downstream side of the gas heater 40 in the exhaust passage L1. The dust collector 50 is supplied with the exhaust gas heat-recovered by the gas heater 40. The dust collector 50 is a device that collects soot dust such as coal ash (fly ash) in the exhaust gas by applying a voltage to the electrodes. The fly ash collected by the dust collector 50 is transported to a coal ash recovery silo (not shown). The temperature of the exhaust gas in the dust collector 50 is, for example, 80 to 120 ° C.

The attraction ventilator 60 is arranged on the downstream side of the dust collector 50 in the exhaust passage L1. The draft fan 60 takes in the exhaust gas from which the fly ash has been removed in the dust collector 50 from the primary side and sends it to the secondary side.

The desulfurization device 70 is arranged on the downstream side of the induction ventilator 60 in the exhaust passage L1. The exhaust gas sent from the induction ventilator 60 is supplied to the desulfurization apparatus 70. The desulfurization device 70 removes sulfur oxides from the exhaust gas. Specifically, the desulfurization device 70 removes the sulfur oxides from the exhaust gas by spraying the mixed liquid (limestone slurry) of limestone and water onto the exhaust gas so that the mixed liquid absorbs the sulfur oxides contained in the exhaust gas. The temperature of the exhaust gas in the desulfurization apparatus 70 is, for example, 50 to 120 ° C.

The gas heater 80 is arranged on the downstream side of the desulfurization apparatus 70 in the exhaust passage L1. Exhaust gas from which sulfur oxides have been removed in the desulfurization apparatus 70 is supplied to the gas heater 80. The gas heater 80 heats the exhaust gas. The gas heater 40 and the gas heater 80 are disposed between the exhaust gas flowing between the air preheater 30 and the dust collector 50 and the exhaust gas flowing between the desulfurization device 70 and a denitration device 90 described later in the exhaust passage L1. It may be configured as a gas gas heater that performs heat exchange with.
In particular, the gas heater 80 heats the exhaust gas to a temperature suitable for the denitration reaction in the subsequent denitration device 90.

The denitration device 90 is arranged downstream of the gas heater 80 in the exhaust passage L1. The exhaust gas heated by the gas heater 80 is supplied to the denitration device 90. The denitration device 90 removes nitrogen oxides from the exhaust gas by a denitration catalyst. In the denitration device 90, the denitration catalyst containing vanadium oxide as a main component, the oxide content of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co, W, Mo. The denitration catalyst described above, which is at least one metal element selected from the group consisting of Nb, Ce, Sn, Ni, and Fe, is used. The temperature of the exhaust gas in the denitration device 90 is, for example, 130 to 200 ° C.

In the denitration device 90, nitrogen oxides are removed from the exhaust gas by the selective catalytic reduction method. According to the selective catalytic reduction method, nitrogen oxides can be efficiently removed from the exhaust gas by producing nitrogen and water from the nitrogen oxides by the reducing agent and the denitration catalyst. The reducing agent used in the selective catalytic reduction method contains at least one of ammonia and urea. When ammonia is used as the reducing agent, ammonia in any state of ammonia gas, liquid ammonia, and aqueous ammonia solution may be used.

More specifically, the denitration device 90 can be configured to inject ammonia gas into the introduced exhaust gas and then bring the mixed gas into contact with the denitration catalyst.

Therefore, the denitration device 90 includes, for example, one or a plurality of denitration catalyst layers, and the denitration catalyst layer includes a plurality of casings, a plurality of honeycomb catalysts housed in the plurality of casings, and a seal member. You may.

More specifically, the casing is composed of a rectangular tubular metal member having one end and the other end opened, and the one end and the other end opened are opposed to the exhaust gas flow path in the denitration reactor, that is, the casing. The exhaust gas may be arranged so as to circulate inside. Further, the plurality of casings may be connected and arranged in a state of being in contact with each other so as to block the flow path of the exhaust gas.

The honeycomb catalyst may be formed in a long shape (a rectangular parallelepiped shape) in which a plurality of exhaust gas circulation holes extending in the longitudinal direction are formed, and the exhaust gas circulation holes may be arranged so that the extending direction is along the exhaust gas passage.

The chimney 100 is connected to the downstream side of the exhaust passage L1. Exhaust gas from which nitrogen oxides are removed by the denitration device 90 is introduced into the chimney 100. Since the exhaust gas introduced into the chimney 100 is heated by the gas heater 80, it is effectively discharged from the upper part of the chimney 100 by the chimney effect. Further, by heating the exhaust gas in the gas heater 80, it is possible to prevent water vapor from condensing above the chimney 100 to generate white smoke. The temperature of the exhaust gas near the outlet of the chimney 100 is, for example, 110 ° C.

<6.1.2 Second combustion system>
FIG. 16 is a diagram showing the configuration of the combustion system 1A according to the second application example. Similar to the combustion system 1, the combustion system 1A is a combustion system using pulverized coal as fuel. In the combustion system 1A, the same reference numerals are used for the same components as the combustion system 1, and the description of their functions will be omitted.

The combustion system 1A differs from the combustion system 1 in that the denitration device 90 is installed immediately after the dust collector 50. Further, a ventilator 60, a desulfurization device 70, and a gas heater 80 are provided downstream of the denitration device 90 in this order from the upstream.

The gas heater 80 in the combustion system 1 heats the exhaust gas to a temperature suitable for the denitration reaction in the denitration device 90 in the subsequent stage. On the other hand, the gas heater 80 in the combustion system 1A heats the exhaust gas to a suitable temperature until it diffuses from the chimney 100 in the subsequent stage.

By installing the denitration device 90 immediately after the dust collector 50, the temperature of the exhaust gas in the denitration device 90 can be set to 130 to 200° C. without providing a gas heater in front of the denitration device 90.

<6.1.3 Third combustion system>
FIG. 17: is a figure which shows the structure of the combustion system 1B which concerns on a 3rd application example. The combustion system 1B is a combustion system that uses natural gas as fuel, unlike the combustion systems 1 and 1A. In the combustion system 1B, the same reference numerals are used for the same components as those of the combustion system 1 and the combustion system 1A, and the description of their functions will be omitted.

As shown in FIG. 17, the combustion system 1B includes a boiler 10 as a combustion device, a natural gas vaporizer 15, an exhaust passage L1, an air preheater 30, a denitration device 90, an induction ventilator 60, and the like. And a chimney 100. On the other hand, in the combustion system 1B, the dust collector and the desulfurizer are not essential components.

The vaporizer 15 vaporizes natural gas supplied from an LNG tank (not shown) and supplies it to the boiler 10. When vaporizing, a method of using seawater (open rack method), a method of producing hot water with a gas burner and heating (submerged combustion method), or an intermediate medium for several steps A method of performing heat exchange may be used.

The denitration device 90 is arranged on the downstream side of the air preheater 30 in the exhaust passage L1. The exhaust gas cooled in the air preheater 30 is supplied to the denitration device 90. The denitration device 90 removes nitrogen oxides from the exhaust gas by a denitration catalyst. The temperature of the exhaust gas in the denitration device 90 is, for example, 130 to 200 ° C.

The downstream side of the exhaust passage L1 is connected to the chimney 100. Exhaust gas from which nitrogen oxides are removed by the denitration device 90 is introduced into the chimney 100. Since the temperature of the exhaust gas in the denitration device 90 is, for example, 130 to 200° C., the exhaust gas introduced into the stack 100 is effectively discharged from the upper part of the stack 100 due to the stack effect. The temperature of the exhaust gas near the exit of the chimney 100 is 110° C., for example.

By arranging the denitration device 90 on the downstream side of the air preheater 30, the temperature of the exhaust gas denitrated by the denitration catalyst becomes low, and the deterioration of the denitration catalyst can be reduced.

<6.1.4 Fourth combustion system>
FIG. 18 is a diagram showing the configuration of a combustion system 1C according to the fourth application example. As shown in FIG. 18, the combustion system 1C is a combustion system used for propulsion of a ship, and includes a fuel supply device 110, an internal combustion engine 120 as a combustion device, a dust collector 130, and an exhaust heat recovery device. 140, a denitration device 150, a chimney 160, an energizing motor 170, a fuel path R1, exhaust paths R2 and R3, a steam path R4, and a power path R5.

The fuel supply device 110 supplies fuel to the internal combustion engine 120 using the fuel passage R1. As the fuel, for example, petroleum-based fuel such as light oil and heavy oil can be used.

The upstream side of the fuel passage R1 is connected to the fuel supply device 110, and the downstream side is connected to the internal combustion engine 120. The fuel passage R1 is a flow path through which fuel is transported from the fuel supply device 110 to the internal combustion engine 120.

The internal combustion engine 120 burns petroleum fuel with air. In the internal combustion engine 120, exhaust gas is generated by burning petroleum-based fuel. The generated exhaust gas is discharged to the dust collector 130 via the exhaust path R2. The internal combustion engine 120 may be, for example, a 2-stroke low-speed diesel engine used in a large ship, or a 4-stroke medium-speed diesel engine used in a ferry or the like, and used in a high-speed boat or small boat. It may be a 4-stroke high-speed diesel engine.

The upstream side of the exhaust passage R2 is connected to the internal combustion engine 120. The exhaust passage R2 is a passage through which exhaust gas generated in the internal combustion engine 120 flows.

The dust collector 130 is arranged on the downstream side of the internal combustion engine 120 in the exhaust passage R2, and the exhaust gas discharged from the internal combustion engine 120 is supplied. The dust collector 130 is a device that collects soot and dust in the exhaust gas. As a method for collecting soot and dust, for example, a method may be used in which a voltage is applied to the electrodes to charge the soot and dust and the soot and dust are collected by using Coulomb force. Alternatively, as in the method implemented by the Venturi scrubber, a soot absorbing liquid is supplied to the Venturi part, the soot and dust absorbing liquid is miniaturized by the exhaust gas speeded up in the Venturi part, and the soot is collected by gas-liquid contact. May be used.

The exhaust heat recovery device 140 is arranged in the exhaust passage on the downstream side of the dust collector 130, and the exhaust gas from which the dust has been removed by the dust collector 130 is supplied. The exhaust heat recovery device 140 recovers exhaust heat from the exhaust gas supplied from the dust collector 130. More specifically, the exhaust heat recovery device 140 includes a turbine device 141 and an exhaust gas economizer 145.

The turbine device 141 includes a gas turbine 142, a steam turbine 143, and a generator 144. The gas turbine 142 and the generator 144, and the steam turbine 143 and the generator 144 are connected to each other. The gas turbine 142 is driven by the exhaust gas supplied from the dust collector 130 via the exhaust path R3. When the gas turbine 142 is driven, the generator 144 connected to the gas turbine 142 is also driven in conjunction with it to generate power. Further, the steam turbine 143 is driven by steam supplied from the exhaust gas economizer 145, which will be described later, via the steam passage R4. When the steam turbine 143 is driven, the generator 144 connected to the steam turbine 143 also generates electricity in conjunction with it. The electric power generated by the generator 144 is supplied to the biasing motor 170 via the electric power line R5.

The exhaust gas economizer 145 uses a water supply tank (not shown) as a heat source of the exhaust gas supplied from the dust collector 130 via the exhaust passage R2 and the exhaust gas supplied from the gas turbine 142 via the exhaust passage R3. Generate steam from the water stored in etc. The steam generated by the exhaust gas economizer 145 is supplied to the steam turbine 143 via the steam passage R4.

The exhaust passage R3 is an exhaust passage different from the exhaust passage R2, and the upstream side is connected to the dust collector 130 and the downstream side is connected to the exhaust gas economizer 145, and the exhaust passage R3 passes through the gas turbine 142 on the way. The exhaust path R3 is a flow path for circulating the exhaust gas supplied from the dust collector 130 to the exhaust gas economizer 145 via the gas turbine 142.

The upstream side of the steam passage R4 is connected to the exhaust gas economizer 145, and the downstream side is connected to the steam turbine 143. The steam passage R4 is a flow path through which steam generated by the exhaust gas economizer 145 flows.

The power path R5 is connected to the generator 144 on the upstream side and to the boosting motor 170 on the downstream side. The electric power path is a flow path through which electric power generated by the generator 144 flows.

The denitration device 150 is arranged in the exhaust passage R2 on the downstream side of the exhaust heat recovery device 140, and the exhaust gas from which the exhaust heat is recovered is supplied. The denitration device 150 removes nitrogen oxides from the exhaust gas with a denitration catalyst. In the denitration device 150, the denitration catalyst containing vanadium oxide as a main component, the oxide content of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co, W, The above denitration catalyst, which is at least one metal element selected from the group consisting of Mo, Nb, Ce, Sn, Ni, and Fe, is used. Since the denitration device 150 is installed on the downstream side of the exhaust heat recovery device 140, the temperature of the exhaust gas in the denitration device 150 is, for example, 130 to 200°C.

In the denitration device 150, nitrogen oxides are removed from the exhaust gas by the selective catalytic reduction method. According to the selective catalytic reduction method, nitrogen oxides can be efficiently removed from exhaust gas by producing nitrogen and water from nitrogen oxides with a reducing agent and a denitration catalyst. The reducing agent used in the selective catalytic reduction method contains at least one of ammonia and urea. When ammonia is used as the reducing agent, ammonia in any state of ammonia gas, liquid ammonia, and aqueous ammonia solution may be used.

More specifically, the denitration device 150 can be configured to inject ammonia gas into the introduced exhaust gas and then bring the mixed gas into contact with the denitration catalyst.

The chimney 160 is connected to the downstream side of the exhaust passage R2. Exhaust gas from which nitrogen oxides have been removed by the denitration device 150 is introduced into the chimney 160. The exhaust gas introduced into the chimney 160 is effectively discharged from the upper portion of the chimney 160 due to the chimney effect because the temperature of the exhaust gas in the denitration device 150 is, for example, 130 to 200°C. In addition, it is possible to prevent condensation of water vapor above the chimney 160 to generate white smoke. The temperature of the exhaust gas near the outlet of the chimney 160 is, for example, 110 ° C.

The energizing motor 170 is installed on the downstream side of the generator 144 in the electric power line R5, and drives so as to energize the rotation of the internal combustion engine 120 around the propeller shaft. Electric power is supplied to the energizing motor 170 from the generator 144 via the electric power path R5, and by using this electric power, the motive power generated by the internal combustion engine 120 is energized.

<6.1.5 Fifth combustion system>
Although not shown, as a fifth application example, a denitration catalyst containing vanadium oxide as a main component, wherein the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, A denitration device provided in a combustion system for incinerating raw garbage, etc., using the above denitration catalyst in which the metal is at least one metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni, and Fe. May be used in. In the denitration device installed after the boiler that burns garbage, the temperature of the exhaust gas may be 150 ° C or lower, but the above denitration catalyst can be used for denitration with a reaction temperature of 80-150 ° C. Because it is possible, it is also useful for such combustion systems.

<6.2 Denitration catalyst formed by coating the base with a catalyst component>
The above denitration catalyst is basically in the form of powder. For example, as disclosed in Japanese Patent Application Laid-Open No. 2005-199108, in a flue gas denitration device installed in a thermal power plant, a catalyst is formed on a honeycomb-shaped substrate. Honeycomb type catalysts coated with components may be used. Also in the present invention, as a sixth application example, the substrate can be coated with the above-mentioned denitration catalyst as a catalyst component.

As the above-mentioned substrate, any substrate can be used as long as it is not deformed at a temperature of 200 ° C. or higher. For example, a metal such as ceramic, pottery, or titanium may be used as the base. Alternatively, a corrugated honeycomb filter made of ceramic fiber paper, glass fiber paper, flame-retardant paper, activated carbon paper, deodorizing paper, honeycomb filter non-woven fabric, felt, or plastic sheet may be used as the base.
Alternatively, a new catalyst or a used catalyst may be further coated with the catalyst component of the present invention. The substrate can have any shape, for example, plate-shaped, pellet-shaped, fluid-shaped, cylindrical, star-shaped, ring-shaped, extruded, spherical, flake-shaped, pastil-shaped, rib-extruded. , Or rib ring shape. For example, the corrugated type honeycomb filter can take any form such as a block type, a rotor type, an oblique type, a deformed block, a strip type, and a mini pleats.

<6.3 Block-shaped denitration catalyst>
Further, for example, as described in Japanese Patent Application Laid-Open No. 2017-32215, a catalyst block such as a honeycomb catalyst may be used in a denitration device provided in a coal-fired power generation facility. As an application example, it is possible to manufacture a catalyst block containing the above denitration catalyst as a catalyst component.

Specifically, for example, 1-50 wt% of CMC (carboxymethyl cellulose) or PVA (polyvinyl alcohol) is mixed as a binder with the above powdery denitration catalyst, and the mixture is kneaded, followed by an extrusion granulator and a vacuum extruder. It is possible to manufacture the catalyst block by extrusion-molding or press-molding with a molding machine such as the above, followed by drying and then firing. Since the binder is burnt off during firing, the weight ratio of the denitration catalyst in the catalyst block after firing is 100 wt %.

In addition, by further mixing, for example, titanium, molybdenum, tungsten, and/or its compounds (particularly oxides), silica, or the like with the above powdery denitration catalyst, by kneading and extruding It is possible to manufacture a catalyst block.

The catalyst block can have any shape, for example, plate shape, pellet shape, fluid shape, columnar shape, star shape, ring shape, extrusion type, spherical shape, flake shape, honeycomb shape, pastille shape, rib. An extrusion type or rib ring type can be used. Further, for example, in the honeycomb-shaped catalyst block, the honeycomb surface may have a polygonal shape such as a triangle, a quadrangle, a pentagon, a hexagon, or a circle.

<6.4 Other uses>
As applications of the above-mentioned denitration catalyst, in 6.1, the combustion system, in 6.2, the denitration catalyst formed by coating the substrate with a catalyst component was described, and in 6.3, the denitration catalyst formed in a block shape was described. The use of the denitration catalyst is not limited to this.
For example, in 6.1.1 and 6.1.2, a combustion system using pulverized coal as a fuel and in 6.1.3 a combustion system using natural gas as a fuel were described. It may be used in combustion systems that use petroleum or biomass fuels instead of charcoal and natural gas. Moreover, although the combustion system used for propulsion of a ship was described in 6.1.4, the above-described denitration catalyst may be used in a combustion system used for propulsion of an automobile instead of a ship.

According to the combustion system according to the above application example, the following effects are achieved.
(1) As described above, in the combustion system 1 according to the application example, the denitration device 90 is arranged on the downstream side of the dust collecting device 50 in the exhaust passage L1 through which the exhaust gas generated in the boiler (combustion device) 10 flows. .. Further, in the above-described embodiment, in the denitration device 90, the denitration catalyst containing vanadium oxide as a main component, the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is , Co, W, Mo, Nb, Ce, Sn, Ni, and Fe, a denitration catalyst of at least one metal element selected from the group was used.
By using the above-mentioned denitration catalyst, in the combustion system 1 according to the above-described embodiment, the denitration efficiency at a low temperature is lower than that of the prior art in the selective catalytic reduction reaction of 200° C. or less using ammonia as a reducing agent. The effect of being even higher can be exhibited.

(2) The combustion system 1A according to the application example further includes the air preheater 30 that recovers heat from the exhaust gas, and the air preheater 30 is arranged on the upstream side of the dust collector 50.
By supplying the exhaust gas whose heat is recovered by the air preheater 30 to the dust collector 50, the load on the dust collector 50 due to the heat of the exhaust gas is suppressed. Further, since the denitration device 90 is not arranged upstream of the air preheater 30 which is usually arranged near the boiler (combustion device) 10 in the exhaust passage L1, ammonia reacts with S in exhaust gas. The air preheater 30 is not clogged due to the generated ammonium sulfate. As a result, the combustion system 1A has a low operating cost.

(3) In the combustion system 1B according to the above application example, the denitration device 90 is arranged on the downstream side of the air preheater 30 in the exhaust passage L1 through which the exhaust gas generated in the boiler (combustion device) 10 flows. Further, in the above-described embodiment, in the denitration device 90, the denitration catalyst containing vanadium oxide as a main component, the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is A denitration catalyst of at least one metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni, and Fe was used.
By using the above-mentioned denitration catalyst, in the combustion system 1A according to the above-described embodiment, the denitration efficiency at a low temperature is improved in the selective catalytic reduction reaction at a temperature of 200° C. or less using ammonia as a reducing agent, as compared with the conventional technique. The effect of being even higher can be exhibited. Further, as a result, it becomes possible to dispose the denitration device 90 on the downstream side of the air preheater 30, so that the temperature of the exhaust gas denitrated by the denitration catalyst becomes low, and the deterioration of the denitration catalyst can be reduced. ..
Further, in the combustion system 1B in the above embodiment, the dust collector and the desulfurization device are not essential components. Therefore, the installation cost can be reduced by simplifying the configuration of the combustion system 1B.

(4) The combustion system 1C according to the application example described above includes an exhaust passage R2 through which exhaust gas generated by combustion of fuel in the internal combustion engine 120 flows, and exhaust gas disposed in the exhaust passage R2 and discharged from the internal combustion engine 120. A combustion system 1C including an exhaust heat recovery device 140 that recovers exhaust heat and a denitration device 150 that is disposed in the exhaust passage R2 and that removes nitrogen oxides from exhaust gas by a denitration catalyst. The denitration catalyst arranged on the downstream side of the exhaust heat recovery apparatus 140 in R2 is a denitration catalyst containing vanadium oxide as a main component, and the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less. The second metal is a denitration catalyst of at least one metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni, and Fe.
By using the above-mentioned denitration catalyst, in the combustion system 1C according to the above-described embodiment, the denitration efficiency at a low temperature is improved in the selective catalytic reduction reaction at a temperature of 200° C. or less using ammonia as a reducing agent, as compared with the conventional technique. The effect of being even higher can be exhibited, and the denitration device can be arranged on the downstream side of the exhaust heat recovery device. Furthermore, it is not essential to heat the exhaust gas immediately before introducing the exhaust gas into the denitration device 150. As a result, the NOx removal catalyst is not exposed to high temperatures, so the deterioration of the NOx removal catalyst is reduced, and the operating cost of the combustion system 1C is reduced.
In addition, the combustion system 1C of the above-described embodiment can have a compact structure because a heater for heating exhaust gas is not essential. As a result, it becomes possible to install the combustion system with the denitration device even in a narrow space such as a ship.

(5) As described above, the exhaust heat recovery device 140 includes the turbine device 141 and the exhaust gas economizer 145, and the exhaust gas economizer 145 collects the exhaust gas discharged from the internal combustion engine 120 and the exhaust gas supplied from the turbine device 141. It is preferable that steam is generated as a heat source, and the turbine device 141 uses the exhaust gas discharged from the exhaust gas engine 120 and the steam supplied from the exhaust gas economizer 145 to generate power.
The exhaust heat recovery device 140 in the above-described embodiment includes the turbine device 141 and the exhaust gas economizer 145, so that the thermal energy generated by the combustion of the fuel in the internal combustion engine 120 can be more effectively utilized. ..

1, 1A, 1B, 1C Combustion system 10 Boiler 15 Vaporizer 30 Air preheater 50 Electric dust collector 90 150 Denitration device 100 160 Chimney 110 Fuel supply device 120 Internal combustion engine 130 Dust collector 140 Exhaust heat recovery device 141 Turbine device 145 Exhaust gas economizer 170 booster motor

Claims (5)

1. A combustion device that burns fuel and
   An exhaust path through which exhaust gas generated by burning the fuel in the combustion device flows, and
   A dust collector arranged in the exhaust path and collecting soot and dust in the exhaust gas,
   A combustion system including a denitration device arranged in the exhaust passage and removing nitrogen oxides from the exhaust gas by a denitration catalyst.
   The denitration device is arranged on the downstream side of the dust collector in the exhaust passage.
   The denitration catalyst is a denitration catalyst containing vanadium oxide as a main component, the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co, W, or Mo. , Nb, Ce, Sn, Ni, and Fe, a combustion system that is a denitration catalyst for at least one metal element selected from the group.
2. The combustion system further comprises an air preheater disposed in the exhaust passage and recovering heat from the exhaust gas,
   The combustion system according to claim 1, wherein the air preheater is arranged on the upstream side of the dust collector.
3. A combustion device that burns fuel and
   An exhaust path through which exhaust gas generated by burning the fuel in the combustion device flows, and
   An air preheater arranged in the exhaust gas path and recovering heat from the exhaust gas,
   A combustion system including a denitration device arranged in the exhaust passage and removing nitrogen oxides from the exhaust gas by a denitration catalyst.
   The denitration device is arranged on the downstream side of the air preheater in the exhaust passage.
   The denitration catalyst is a denitration catalyst containing vanadium oxide as a main component, the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co, W, or Mo. , Nb, Ce, Sn, Ni, and Fe, a combustion system that is a denitration catalyst for at least one metal element selected from the group.
4. An internal combustion engine that burns fuel and
   An exhaust path through which exhaust gas generated by combustion of the fuel in the internal combustion engine flows, and
   An exhaust heat recovery device arranged in the exhaust passage and recovering exhaust heat from the exhaust gas discharged from the internal combustion engine.
   A combustion system provided with a denitration device arranged in the exhaust passage and for removing nitrogen oxides from the exhaust gas by a denitration catalyst.
   The denitration device is arranged on the downstream side of the exhaust heat recovery device in the exhaust passage.
   The denitration catalyst is a denitration catalyst containing vanadium oxide as a main component, the content of the oxide of the second metal is 1 wt% or more and 40 wt% or less, and the second metal is Co, W, or Mo. , Nb, Ce, Sn, Ni, and Fe, a combustion system that is a denitration catalyst for at least one metal element selected from the group.
5. The exhaust heat recovery device includes a turbine device and an exhaust gas economizer.
   The exhaust gas economizer generates steam by using the exhaust gas discharged from the internal combustion engine and the exhaust gas supplied from the turbine device as a heat source,
   The combustion system according to claim 4, wherein the turbine device generates electricity by using exhaust gas discharged from the internal combustion engine and steam supplied from the exhaust gas economizer.

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