JPWO2014054607A1 - Marine exhaust gas treatment equipment - Google Patents

Abstract

[PROBLEMS] To improve exhaust gas processing efficiency in a limited space in a ship and to provide an exhaust gas processing apparatus for an internal combustion engine. [Solution] An apparatus (A) for selectively reducing NOx in exhaust gas, which is provided in an exhaust gas system of a marine internal combustion engine using heavy oil as fuel, and hydrolyzing urea upstream of the apparatus (A) And a device (C) containing a urea hydrolysis device (B) as a NOx removal gas, and the device (B) comprises urea water and air input means, and a urea hydrolysis catalyst, C) is provided so as not to come into contact with exhaust gas, and the exhaust gas is configured to pass through the device (C) and contact with the NOx removal gas supplied from the device (B) in the device (A). An exhaust gas treatment apparatus for a ship characterized by comprising:

Description

  The present invention relates to an exhaust gas treatment apparatus for an internal combustion engine by improving the exhaust gas treatment efficiency in a limited space in a ship. In particular, the present invention relates to an exhaust gas treatment device for a marine internal combustion engine using heavy oil as fuel.

  The exhaust gas discharged from the diesel engine contains contaminants such as HC (hydrocarbon), CO (carbon monoxide), NOx (nitrogen oxide), and PM (Particulate Matter). Among these pollutants, NOx is difficult to purify with an oxidation catalyst or a three-way catalyst put to practical use in gasoline automobiles. As a promising catalyst capable of purifying NOx, a selective reduction type NOx catalyst (hereinafter referred to as SCR catalyst). ) Is being developed.

Examples of the SCR catalyst include binary composite oxides such as TiO ₂ or SiO ₂ —TiO ₂ , WO ₃ —TiO ₂ , SiO ₂ —TiO ₂ , or WO ₃ —SiO ₂ —TiO ₂ , MoO ₃ —SiO _2. -Supports such as ternary complex oxides such as TiO ₂ , V, Cr, Mo, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, W, In, Ir, etc. 2. Description of the Related Art A catalyst having a honeycomb structure that supports components and reducing NOx in the presence of a reducing agent such as ammonia and converting it into nitrogen gas is known.
4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O (1)
NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O (2)
6NO ₂ + 8NH ₃ → 7N ₂ + 12H ₂ O (3)
Also known is a catalyst in which a carrier layer of fine particles having catalytic activity such as zeolite is formed on a monolysis support.

  At this time, as a method for supplying ammonia as a reducing agent, a method is known in which urea is added from an aqueous urea tank to an exhaust system upstream of the SCR catalyst to generate ammonia. Urea is hydrolyzed by the heat of exhaust gas or by a hydrolysis catalyst to produce ammonia, but the thermal decomposition of urea by the heat of exhaust gas changes to high melting point substances such as cyanuric acid, isocyanic acid, melamine, etc., and decomposition efficiency It is known that these substances clog the inside of the flue, and there is a problem that the NOx removal performance is lowered or the downstream NOx removal performance is lowered.

  Japanese Patent Application Laid-Open No. 2005-344597: (Patent Document 1) proposes that urea water is vaporized and supplied, and urea is hydrolyzed to ammonia with a honeycomb-shaped, plate-shaped or granular catalyst. . However, even with this method, it has been difficult to significantly suppress the formation of high melting point substances such as cyanuric acid, isocyanic acid, and melamine. In addition, if the temperature control, etc., is unsatisfactory for some reason, vaporization will be insufficient, urea may precipitate, urea may change to a high melting point material, and catalyst performance may not be fully demonstrated. Sometimes became unstable.

In addition, a method is disclosed in which ammonia is supplied to a cartridge in which urea is stored together with zeolite in a solid state by supplying the stored water under heating to cause hydrolysis. (Japanese Patent Laid-Open No. 2002-89241: Patent Document 2)
However, in this method, the cartridge in which urea is stored in a solid state together with the zeolite varies depending on the displacement of the engine (internal combustion engine) and the travel distance, but needs to be replaced frequently, and the coexistence state of the solid urea and the zeolite As a result, the exhaust gas treatment performance could not be obtained, and the stable exhaust gas treatment performance could not be obtained during the period from the start of running to the stable running. Further, it is difficult to completely suppress the production of the high melting point substance, and there is a problem in that the production efficiency of ammonia is reduced and harmful substances are produced. Furthermore, since the reaction temperature range is as narrow as 90 to 100 ° C. and the reaction rate is slow, the method for supplying ammonia as a reducing agent is not always satisfactory.

  Japanese Patent Application Laid-Open No. 2001-27112 (Patent Document 3) arranges a vaporizer container filled with zeolite particles in a pipe through which exhaust gas flows, and urea water and water from the outside of the pipe are placed in the vaporizer container. In the denitration apparatus in which urea is decomposed and discharged by heat supplied from the exhaust gas, and the ammonia and the exhaust gas are mixed and brought into contact with the denitration catalyst, the temperature in the vaporizer is 60 to 140 ° C. Thus, a denitration device that supplies water into the vaporizer is disclosed.

  However, in this method, it is difficult to arbitrarily control the amount of ammonia generated, and if the amount of ammonia produced is small, the target denitration performance may not be obtained, while if excessive ammonia is produced, There is a problem that excess ammonia leaks to the atmosphere. Further, the zeolite as the catalyst in the vaporizer is not completely isolated from the exhaust gas, and the catalyst may be deteriorated due to the mixture of the exhaust gas into the vaporizer.

Further, a method has been proposed in which a metal complex resin or urease is used as a catalyst, and urea is converted to ammonium carbonate that has a reaction temperature of 70 ° C. or less and is highly soluble in water and generates ammonia at a relatively low temperature. (Japanese Unexamined Patent Application Publication No. 2005-273509 (Patent Document 4))
However, although the generation of high-melting point substances can be suppressed, even if such complex catalysts or enzyme catalysts are used in a lump, they may become powdered over time and cause clogging of the piping. Gradually decreased, and there was a problem that it could not be used stably for a long time.

In order to improve such problems, the applicant of the present application has prepared a catalyst obtained by immersing a stainless steel honeycomb substrate in a zeolite particle dispersion containing a peroxy compound and electrodepositing a zeolite thin film on the honeycomb substrate surface. Discloses that generation of a high melting point substance can be suppressed, urea can be efficiently decomposed, and ammonia can be stably supplied without clogging of piping and the like. (Japanese Unexamined Patent Application Publication No. 2009-197762: Patent Document 5)
Further, the applicant of the present application immerses a honeycomb substrate made of stainless steel in a metal oxide fine particle dispersion containing a peroxy compound or a fibrous substance, and electrodeposits metal oxide fine particles on the surface of the honeycomb substrate to form metal oxide fine particles. The catalyst in which the layer is formed is excellent in adhesion to the base material, wear resistance, strength, etc., and when used for hydrolysis of urea, it can suppress the formation of a high melting point substance and efficiently use urea. It is disclosed that ammonia can be stably supplied without clogging of piping and the like. (Japanese Unexamined Patent Application Publication No. 2009-214045: Patent Document 6)

JP 2005-344597 A JP 2002-89241 A JP 2001-271112 A JP 2005-273509 A JP 2009-197762 A JP 2009-214045 A

  The prior arts disclosed above all relate to the exhaust gas treatment for automobiles equipped with diesel engines with a high rotational speed using light oil as fuel, and no proposal has been made regarding the treatment of exhaust gas for ships. In particular, exhaust gas treatment for marine diesel engines is a limited space due to the special conditions of marine vessels, and heavy oil is mainly used for fuel in the marine vessels, which has a higher sulfur content than light oil, and aromatic carbonization. Due to the large amount of hydrogen and the like, a large amount of dust having sulfur and carbonaceous matter as the core is discharged in addition to NOx.

  Further, in a low-speed two-cycle engine used for a marine diesel engine, particularly a main engine such as a large ship, it is desired that the temperature of the exhaust gas is as low as about 200 ° C. and can be processed even at a low temperature.

  Under such circumstances, in the exhaust gas treatment apparatus for ships, it is predicted that the processing becomes difficult even if the conventionally known automobile exhaust gas treatment apparatus is diverted as it is. Further, simply increasing the size of the exhaust gas treatment device itself has a limit in a ship with limited space. In view of these, the present inventors have found that the method of adding urea is important from the viewpoint of processing space, reaction temperature, and the like.

  First, the inventors of the present application conducted a test by directly supplying urea from the urea water tank to the exhaust system upstream of the SCR catalyst without hydrolyzing urea with the hydrolysis catalyst. Therefore, the reaction temperature is limited, urea is not sufficiently hydrolyzed, the NOx removal performance is insufficient, and it cannot withstand long-term operation.

  Therefore, we considered in advance that urea is decomposed by a hydrolysis apparatus equipped with a urea hydrolysis catalyst outside the exhaust system and ammonia is supplied, but in ships, it is necessary to provide a space to install a hydrolysis apparatus outside. There is a problem, and a separate heat source for hydrolysis is required, and since the energy source mounted on the ship is limited, the supply of ammonia becomes insufficient and the NOx removal performance becomes insufficient. There was a thing.

  Furthermore, a method for effectively utilizing the heat of exhaust gas by providing a hydrolysis device inside the exhaust system upstream of the SCR catalyst was adopted. It has been found that the catalyst layer is clogged, the hydrolysis activity rapidly decreases, and it cannot cope with long-time operation.

Based on the above process, the hydrolysis equipment was isolated from the exhaust gas, and the exhaust gas treatment method was used to hydrolyze urea using the heat of the exhaust gas to supply ammonia. The effect of dust with sulfur and carbonaceous matter as the core The urea hydrolysis performance is the same as that of exhaust gas treatment for automobile diesel engines, and ammonia can be sufficiently supplied, so that NOx removal performance is improved and it is maintained for a long time to complete the present invention. It came to.
[1] An apparatus (A) that is provided in an exhaust gas system of a marine internal combustion engine that uses heavy oil as fuel, selectively hydrolyzes NOx in the exhaust gas, and hydrolyzes urea upstream of the apparatus (A). And a device (C) containing a urea hydrolysis device (B) as a NOx removal gas.
The device (B) includes urea water and air input means, and a urea hydrolysis catalyst, and is provided so as not to come into contact with exhaust gas in the device (C).
An exhaust gas treatment apparatus for a ship, characterized in that the exhaust gas passes through the apparatus (C) and is in contact with the NOx removal gas supplied from the apparatus (B) in the apparatus (A).
[2] The marine exhaust gas treatment device according to [1], wherein a supercharger is provided upstream of the device (C) containing the device (B).
[3] The marine exhaust gas treatment device according to [1] or [2], wherein the rated rotational speed of the internal combustion engine is in a range of 50 to 250 rpm.
[4] The urea decomposition catalyst of the apparatus (B) is a titanium oxide catalyst, and the titanium oxide catalyst serves as an active ingredient in a titanium oxide support as V, W, Mo, Cr, Mn, Fe, Ni, Cu. [1] A marine exhaust gas treatment device on which one or more metals or metal oxides selected from the group consisting of Ag, Au, Pd, Y, Ce, Nd, In, and Ir are supported.
[5] The titanium oxide-based support is titanium oxide or a titanium oxide composite oxide containing at least one oxide selected from Si, W, Mo, Zr, and Ba together with titanium oxide. Ship exhaust gas treatment equipment.
[6] The marine exhaust gas treatment device according to [4] or [5], wherein the titanium oxide-based catalyst is a honeycomb-shaped molded body, a film-shaped molded body, a corrugated molded body, or a granular molded body.
[7] The urea decomposition catalyst of the apparatus (B) is a zeolitic catalyst, and the zeolitic catalyst is a honeycomb-shaped molded body, a film-shaped molded body, a corrugated molded body, or a granular molded body [1] or [4] ] Exhaust gas treatment equipment for ships.
[8] The urea decomposition catalyst of the device (B) is a catalyst in which metal oxide fine particles are attached to a conductive honeycomb substrate, corrugated substrate or network support, and the metal oxide particles are Mg, One or more selected from the group consisting of Ca, Ba, La, Ce, Ti, Zr, V, Cr, Mo, W, Mn, Zn, Al, Si, P, Sb, Cu, Fe, Ru, Co, Re [1] or [4] a marine exhaust gas treatment apparatus comprising the above metal oxide.
[9] The marine exhaust gas treatment device according to [8], wherein the base material of the urea decomposition catalyst of the device (B) is a corrugated base material.
[10] The marine exhaust gas treatment device according to [1] or [4], wherein the reaction temperature when decomposing urea in the device (B) is in the range of 150 to 280 ° C.
[11] The apparatus (A) includes a NOx removal catalyst, the catalyst being a titanium oxide catalyst, and the titanium oxide catalyst as an active ingredient in a titanium oxide carrier as V, W, Mo, Cr, Mn, Fe Exhaust gas treatment equipment for ships according to [1], in which one or more metals selected from the group consisting of Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, In, and Ir or a metal oxide are supported .

  According to the present invention, the urea hydrolyzer is provided in the exhaust system of a low-speed marine internal combustion engine that uses heavy oil as fuel, and the urea hydrolyzer is suppressed from clogging and deactivation in a short time even under low temperature conditions. Can be selectively hydrolyzed to ammonia, so that it is possible to provide a marine exhaust gas treatment device that can stably selectively reduce NOx in exhaust gas and remove it.

FIG. 1 is a schematic diagram of a NOx selective removal apparatus. FIG. 2 shows a flow model of the NOx removal test apparatus. FIG. 3 shows a flow model of the NOx removal test apparatus. FIG. 4 shows a flow model of the NOx removal test apparatus.

Hereinafter, the exhaust gas treatment apparatus of the present invention will be specifically described.
[Ship exhaust gas treatment equipment]
The marine exhaust gas treatment apparatus according to the present invention is provided in an exhaust gas system of a marine internal combustion engine using heavy oil as fuel.

  In the device (C), a device (B) provided with urea water and air input means, heat exchange means and, if necessary, urea hydrolysis catalyst is provided so as not to come into contact with the exhaust gas. It passes through (C) and is configured to contact the NOx removal gas supplied from the device (B) in the device (A).

  A schematic diagram of such an apparatus according to the present invention is shown in FIG.

  In the present invention, the fuel used in the internal combustion engine provided with the exhaust gas treatment device is preferably heavy oil. As the heavy oil, there are typically A heavy oil (mixed oil of 90% light oil and 10% residual oil), B heavy oil (usually mixed oil of 50% light oil and 50% residual oil), etc. Or the heavy oil of the same grade as A heavy oil is preferable. In addition, light oil can also be used, and furthermore, light oil can also be mixed and used as needed.

  The boiling point range of heavy oil used in the present invention is approximately 300 to 400 ° C., but is not limited thereto. A preferred boiling range is approximately 300 to 380 ° C. For comparison, the boiling point range of light oil is approximately 180 to 350 ° C. Moreover, the sulfur concentration in light oil is set to 50 ppm or less as S.

  The rated rotational speed of the marine internal combustion engine varies depending on the displacement of the internal combustion engine, but is preferably in the range of 50 to 250 rpm, more preferably 55 to 200 rpm.

  The present invention is extremely effective for exhaust gas treatment at such a rotational speed.

  During steady operation, the rotational speed does not greatly exceed 250 rpm.

  Usually, an internal combustion engine is provided with a supercharger in order to increase combustion efficiency, energy efficiency, etc., but in the ship exhaust gas treatment device of the present invention, it is downstream of the ship internal combustion engine, and the device ( A supercharger is preferably provided upstream of the device (C) containing B).

  When the NOx selective removal device is installed in front of the supercharger (upstream), exhaust gas can be treated at high temperature, so the NOx selective reduction efficiency is high, but on the other hand, the oxidation rate of the sulfur component is high due to the high temperature The problem of accumulation of sulfur compounds in the turbocharger occurs, and the exhaust gas energy is taken away by the heat capacity of the NOx selective removal device, so even if the engine load is increased, the target exhaust gas amount is immediately Even if the engine load is further reduced, the inflow of exhaust gas from the supercharger does not decrease immediately, and the responsiveness of the supercharger itself becomes extremely poor. Furthermore, since the NOx selective removal device becomes a high-pressure device, there is a problem of cost that it is expensive and requires maintenance costs. Furthermore, there is a drawback that the urea hydrolysis apparatus (B) and the NOx selective removal apparatus (A) which are isolated as in the present invention described later cannot be made compact in an integrated manner.

  In the present invention, the NOx selective removal device is provided on the downstream side of the supercharger. At this time, in order to supply ammonia gas as a reducing agent, the urea hydrolysis device (B) is disposed upstream of the NOx selective removal device (A). Are separated from each other so as not to come into direct contact with the exhaust gas.

  The exhaust gas after burning heavy oil in the internal combustion engine is first sent to the device (C). In the apparatus (C), there is provided a urea hydrolysis apparatus (B) that decomposes urea into ammonia as a NOx removal gas without contacting with the exhaust gas.

Urea hydrolysis equipment (B)
In the apparatus (B), ammonia gas and carbon dioxide gas are converted by hydrolysis reaction without contacting with the exhaust gas, and this ammonia gas is supplied to the apparatus (A) for selectively reducing NOx in the downstream exhaust gas. Air and urea are directly introduced into the device (B) provided in the device (C).

  The amount of catalyst to be charged in the device (B) is appropriately designed and used according to the type of fuel for the ship, the displacement, etc.

  Urea is preferably supplied as an aqueous solution, and the concentration of urea water is generally in the range of 10 to 50% by mass.

  If the concentration of urea water is high, it may vary depending on the reaction temperature, but the ammonia production rate may decrease due to the formation of a high melting point substance. Even if the concentration of urea water is too low, water is excessive, Inefficient in terms of heating energy, urea water supply, etc.

  In addition, it is possible to supply ammonia gas directly instead of the urea hydrolysis apparatus (B) separately, but there are concerns about safety because it is expensive or high-pressure gas on board, In addition, there is a problem that ammonia gas itself has extremely strong toxicity.

  The reaction temperature for decomposing urea is preferably 150 to 280 ° C, more preferably 180 to 280 ° C. When the temperature is low, the ammonia production rate is low, and the selective reduction of NOx in the exhaust gas may be insufficient. It is difficult to heat the exhaust gas of a marine internal combustion engine beyond the above range, and even if it is possible, the ammonia production rate tends to decrease due to the formation of high melting point substances such as cyanuric acid, isocyanic acid and melamine. .

  The exhaust gas temperature downstream of the supercharger is approximately 150 to 280 ° C.

  Moreover, you may heat an apparatus (B) as needed, and heating can be performed by contacting waste gas with the heat exchanger provided in the apparatus (B) exterior. Moreover, you may provide a heating means separately as needed. Examples of the heating means include a heating wire. Depending on the exhaust gas temperature, heating may not always be necessary.

As the urea decomposition catalyst used in the apparatus (B) , the following (1) to (3) are used (these are referred to as a first aspect, a second aspect, and a third aspect in order).
(1) Titanium oxide-based catalyst The first aspect of the urea decomposition catalyst used in the device (B) is a titanium oxide-based catalyst, and the titanium oxide-based catalyst has V, W, Mo as active metal components on the titanium oxide-based support. It is preferable that one or more metals selected from the group consisting of Cr, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, In, and Ir are supported.

  The titanium oxide carrier is preferably titanium oxide or a titanium oxide composite oxide containing at least one oxide selected from Si, W, Mo, Zr, and Ba.

_{Specifically, TiO 2, TiO 2 -SiO 2} , TiO 2 -WO 3, TiO 2 -MoO 3, TiO 2 -ZrO 2, TiO 2 -SiO 2 -WO 3, TiO 2 -SiO 2 -MoO 3 , etc. Is mentioned.

  The content of oxide other than titanium oxide in the titanium oxide-based carrier containing at least one oxide of an element selected from Si, W, Mo, Zr, and Ba is 1 to 40% by mass as an oxide, and further 2 It is preferable to be in the range of ˜30% by mass. When it is within this range, the catalyst performance becomes high.

  The active metal is preferably one or more metals selected from the group consisting of V, W, Mo, Cr, Mn, Fe, Ni, Cu, Ag, Au, Pd, Y, Ce, Nd, In, and Ir. The supported amount of the active metal component is preferably in the range of 0.1 to 20% by mass, more preferably 0.5 to 10% by mass as a metal in the obtained catalyst. If it is within this range, the decomposition activity of urea increases.

There are no particular limitations on the method for supporting the active metal component as long as a predetermined amount of metal can be supported on the titanium oxide-based carrier, and a conventionally known method can be employed. For example, an impregnation method, a kneading method, a dip coating method and the like can be mentioned. The specific surface area of the titanium oxide-based catalyst is generally 50~350m ² / g, more preferably in the range of 100 to 300 m ² / g. Within this range, there are many solid acid sites and good dispersibility of the active metal, so that sufficient hydrolysis performance is exhibited.

  In the present invention, the specific surface area is measured by the well-known BET method.

The titanium oxide-based catalyst is used as a molded body, and a conventionally known molded body such as a honeycomb-shaped molded body, a corrugated molded body, or a granular molded body (pellet) can be used.
(2) Zeolite Catalyst Next, as a second embodiment of the urea decomposition catalyst used in the apparatus (B), there is a zeolite catalyst disclosed in Japanese Patent Application Laid-Open No. 2009-197762 filed by the applicant of the present application.

  Conventionally known synthetic zeolite and natural zeolite can be used as the zeolite. In addition, zeolite is usually crystalline aluminosilicate in a narrow sense, but is not limited to this. Crystalline aluminophosphate (SAPO), crystalline aluminophosphate (ALPO), crystalline titanosilicate ( TS) can also be used. Among these, one or more selected from ZSM-5 type zeolite, mordenite type zeolite, faujasite type zeolite, A type zeolite, L type zeolite, and β zeolite are preferable. These zeolites are excellent for urea decomposition.

  The average particle size of the zeolite particles is preferably in the range of 0.01 to 10 μm, more preferably 0.02 to 5 μm. When it is in this range, the catalyst layer can be easily formed and the adhesiveness to the substrate is excellent.

  The zeolite-based catalyst is also preferably a honeycomb-shaped molded body, a film-shaped molded body, a corrugated molded body, a granular molded body, or the like.

  The honeycomb-shaped formed body is obtained by forming a zeolite catalyst layer on a known honeycomb substrate.

  The thickness of the zeolite catalyst layer is preferably in the range of 0.1 μm to 5 mm, more preferably 0.2 μm to 2 mm. Within this range, it has high hydrolysis performance, sufficient strength, and wear resistance.

  The zeolite catalyst layer may contain an inorganic oxide that acts as a zeolite and a binder, and the inorganic oxide is preferably an inorganic oxide derived from a peroxo compound.

  The zeolite content in the zeolite catalyst layer is preferably in the range of 50 to 99 mass%, more preferably 70 to 98 mass% as the solid content, and the content of the inorganic oxide derived from the peroxo compound is 1 as the solid content. It is preferable to be in the range of ˜50 mass%, more preferably 2˜30.

  In the present invention, fibrous fine particles such as fibrous silica, fibrous alumina, fibrous titanium oxide, and fibrous silica alumina may be included in addition to the zeolite and the inorganic oxide that acts as a binder.

  Furthermore, the zeolite catalyst layer may contain colloidal particles having an average particle diameter of 2 to 300 nm, preferably 5 to 100 nm.

  The content of such fibrous fine particles and colloidal particles is such that the zeolite content in the zeolite catalyst layer is in the range of 50 to 99% by mass as the solid content, and the content of the inorganic oxide derived from the peroxo compound is solid. If it is the range of 1-50 mass% as a minute, it can use without a restriction | limiting especially. A honeycomb formed body having a zeolite catalyst layer is obtained by immersing a metal honeycomb substrate having conductivity described above in a zeolite particle dispersion containing a peroxo compound, and applying a DC voltage to the conductive substrate and the dispersion. Can be manufactured.

  The film-shaped molded body is a substrate having a net-like shape and using a conductive support such as copper, nickel, aluminum, and stainless steel, and a catalyst layer is formed on the surface of the substrate. The material of the net-like support is the same as that of the honeycomb substrate described above. The mesh support has conductivity, and a mesh support having a mesh size (sometimes referred to as an opening) of 0.03 to 10 mm, more preferably 0.1 to 5 mm is preferably used. When the mesh in this range is used, the strength of the support is high and sufficient ventilation can be achieved, so that the reaction activity is high.

  The thickness of the zeolite catalyst layer is preferably in the range of 0.1 μm to 5 mm, more preferably 0.2 μm to 2 mm, as in the honeycomb formed body. Such a method for producing a film-like formed body having a zeolite catalyst layer can be produced in the same manner except that the above-mentioned reticulated support is used in place of the honeycomb substrate in the production of the honeycomb-shaped formed body.

In the case of a corrugated body, the shape is a laminate of thin plates of corrugated ceramic fibers or glass fibers, and through holes are provided, and the size of the through holes can be changed by changing the corrugated pitch. Can do. The density of the through holes may be 20 cells / inch ² to more than 500 cells / inch ² and is appropriately selected according to the scale of the ship, the area where the apparatus of the present invention is installed, and the like.

  The thickness of the zeolite catalyst layer is preferably in the range of 0.1 μm to 5 mm, more preferably 0.2 μm to 2 mm, as in the honeycomb formed body. The method for producing a corrugated shaped body having such a zeolite catalyst layer can be produced in the same manner except that the corrugated base material is used instead of the honeycomb base material in the production of the honeycomb shaped body.

  As a granular molded object, it is a molded object which consists of a zeolite and a binder disclosed by Unexamined-Japanese-Patent No. 2004-238209 by application of the present applicant, (i) Average particle diameter (D) is 0.5-0.5. Zeolite microspheres in the range of 5 mm can be suitably used. Also in this case, the same zeolite as described above is used for the type of zeolite, the particle diameter, and the like.

  In the granular compact, it may be present between the zeolite particles to increase the plasticity at the time of molding to improve the moldability, and may contain a binder for increasing the compression strength and wear resistance of the resulting granular compact. Specific examples include clay minerals such as kaolin, montmorillonite, bentonite, allophane, and sepiolite, as well as oxide particles such as alumina, silica, zirconia, titania, silica / alumina, silica / zirconia, and composite oxide particles. . Such a binder preferably has a particle size in the range of about 10 nm to 5 μm, and preferably smaller than the particle size of the zeolite used. Further, the shape is not particularly limited, and may be any of spherical, fibrous, and irregular shapes.

The zeolite content in the granular compact is preferably in the range of 60 to 98% by mass, more preferably 75 to 95% by mass, and the binder content is 2 to 40% by mass, more preferably 5 to 25% by mass. It is preferable to be in the range. When the binder is contained within such a range, the hydrolysis performance is high, and the compression strength and wear resistance of the obtained granular molded body can be increased.
(3) Metal oxide fine particle adhesion catalyst The third aspect of the urea decomposition catalyst of the apparatus (B) is a honeycomb substrate made of a conductive material such as aluminum, tin, various stainless steels, a corrugated substrate or a net-like catalyst. A metal oxide fine particle adhesion catalyst in which metal oxide fine particles adhere to a support. Examples of such a metal oxide fine particle adhesion catalyst include the metal oxide fine particle adhesion catalyst disclosed in Japanese Patent Application Laid-Open No. 2009-214045 filed by the applicant of the present application.

The metal oxide fine particles used in the present invention include Mg, Ca, Ba, La, Ce, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Zn, Al, Si, P, Sb, Cu, and Fe. , Metal oxide particles (including composite metal oxide fine particles) made of a metal oxide of one or more elements selected from Ru, Co, and Re. Among these, the metal oxide fine particles _{SiO 2, Al 2 O 3,} TiO 2, ZrO 2, NiO, Fe 2 O 3, CoO, RuO 2, CuO, Re 2 O 3, WO 3, V 2 O One or more selected from ₅ , Nb ₂ O ₅ and MnO ₂ are preferred. Such metal oxide fine particles can be attached to a substrate or a support by applying a DC voltage, and have high activity in urea hydrolysis reaction, and can be suitably used.

  The average particle diameter of the metal oxide fine particles is preferably in the range of 10 nm to 10 μm, more preferably 20 nm to 5 μm. Within this range, the catalyst for hydrolysis reaction having high adhesion, strength, and wear resistance to the substrate can be produced without causing cracks in the fine particle layer.

  The thickness of the metal oxide fine particle layer is preferably in the range of 0.1 μm to 5 mm, more preferably 0.2 μm to 2 mm. If the temperature is within this range, sufficient hydrolysis performance can be exhibited.

  The content of the metal oxide fine particles in the metal oxide fine particle layer is preferably in the range of 50 to 99% by mass, more preferably 70 to 98% by mass as the solid content. Within this range, the adhesion to the substrate is high, the strength and wear resistance are excellent, and the metal oxide fine particle layer has high density, strength, wear resistance and the like.

  In the present invention, in order to improve the adhesion between the catalyst layer and the substrate, fibrous fine particles may be included in addition to the metal oxide fine particles. Examples of the fibrous fine particles include fibrous silica, fibrous alumina, fibrous titanium oxide, and fibrous silica alumina.

  The fibrous fine particles have a length of 50 nm to 10 μm, preferably 100 nm to 5 μm, a diameter of 10 nm to 2 μm, preferably 20 nm to 2 μm, and an aspect ratio length / diameter of 5 to 1,000, Preferably it is the range of 10-500.

  When the size of the fibrous fine particles is in the above range, the adhesion between the metal oxide fine particle layer formed and the honeycomb substrate is excellent in strength, wear resistance, and the like.

  The amount of fibrous fine particles used is preferably in the range of 0.1 to 20 mass%, more preferably 0.5 to 10 mass% of the metal oxide fine particles. If it is in this range, the amount of fibrous fine particles will not be too much, so the hydrolysis performance of urea is high and the adhesion to the substrate is also high.

  Further, in the present invention, colloidal particles having an average particle diameter of 2 to 300 nm, preferably 5 to 100 nm can be used. The colloidal particle is not particularly limited as long as it is a particle charged on the particle surface, and examples thereof include colloidal particles such as titanium oxide, alumina, silica, silica / alumina, and zirconia. When such colloidal particles are included, the metal oxide fine particles tend to be laminated when the direct current voltage is applied and the metal oxide fine particles are laminated in the manufacturing method described later. There is a tendency that the density of the fine particle layer is improved and the strength and wear resistance are improved.

  Furthermore, the metal oxide fine particle layer may contain an inorganic oxide that acts as a binder in addition to the fibrous fine particles and colloidal particles, and is preferably an inorganic oxide derived from a peroxo compound. Examples of peroxo compounds include peroxotitanic acid, peroxoniobic acid, peroxotungstic acid, peroxomolybdic acid, and salts thereof.

  The content of the inorganic oxide derived from the peroxo compound in the metal oxide fine particle layer is preferably in the range of 1 to 50% by mass, more preferably 2 to 30% by mass as the solid content. The content of such fibrous fine particles, colloidal particles, and the inorganic oxide is determined as long as the content of the metal oxide fine particles in the metal oxide fine particle layer is in the range of 50 to 99% by mass as a solid content. It can be used without particular limitation in the range of the content of.

  The above-described method for producing a catalyst having a metal oxide fine particle layer includes a metal substrate or a film-like support having conductivity described above, and a metal oxide containing fibrous fine particles, colloidal particles, and a peroxo compound as necessary. It is immersed in the fine particle dispersion and a DC voltage is applied to the conductive substrate and the dispersion.

  In the present invention, in any of the catalyst of the first aspect, the catalyst of the second aspect, and the catalyst of the third aspect, a corrugated structure using a corrugated substrate having a wavy structure at least in part. It is preferable to use a molded body catalyst.

  The corrugated shaped catalyst is superior to honeycomb carriers made by extruding ceramic, and is superior in terms of light weight, large porosity, resistance to thermal shock, and resistance to cracking. It can be suitably used as a catalyst. Moreover, even if it is a complicated structure, the processing is relatively easy, the thickness of the partition wall of the catalyst layer can be reduced, it is difficult to generate a differential pressure, and clogging due to particulates or the like can be suppressed, Since the geometric surface area per volume of the molded catalyst is large, it can be suitably used for exhaust gas treatment for ships with limited space.

  Such a corrugated molded body is formed by forming the titanium oxide-based composite oxide layer on a laminated corrugated base material made of an inorganic fiber sheet such as ceramic fiber or glass fiber, for example, in the case of the catalyst of the first aspect. It can be produced by supporting a metal.

  Specifically, for example, the catalyst of the first aspect can be prepared as follows, but is not limited thereto.

  Titanium oxide particles having an average particle size of approximately 0.5 to 2.0 μm and a slurry for a titanium oxide carrier by mixing inorganic sols such as silica sol, alumina sol, silica / alumina sol, zirconia sol, and titania sol as a binder. To prepare. At this time, the concentration of the slurry (mixture) for the titanium oxide-based carrier is preferably in the range of about 1 to 50% by mass, more preferably 20 to 40% by mass as the solid content. At this time, the content of the binder is preferably in the range of 1 to 10% by mass, more preferably 2 to 5% by mass in the total solid content.

  Separately, an active metal component precursor such as ammonium metavanadate powder (AMV) and ammonium paratungstate powder (APT) and a monoethanolamine solution (MEA) are mixed with water to prepare a dispersion, and then heated. Then, a dissolving solution of each powder (active metal component powder) is prepared.

  Next, a slurry for preparing a catalyst is prepared by mixing a solution of the active metal component with the slurry for a titanium oxide carrier. The catalyst preparation slurry also preferably has a solid concentration in the range of 1 to 50 mass%, more preferably 20 to 40 mass%.

  Next, the corrugated substrate is immersed in the slurry for catalyst preparation, and then the corrugated substrate is pulled up and dried to form a catalyst layer on the corrugated substrate. The formation amount of the catalyst layer can be appropriately adjusted depending on the pulling speed or the number of immersions.

  Thereafter, a corrugated shaped catalyst for urea hydrolysis can be prepared by heat treatment. The heat treatment temperature at this time is preferably in the range of 150 to 700 ° C, more preferably 300 to 550 ° C.

  At this time, the formation amount of the catalyst layer with respect to the corrugated substrate is preferably in the range of about 100 to 500% by mass, more preferably 250 to 400% by mass.

  In the present invention, the exhaust gas passes through the device (C), and is configured to contact the NOx removing gas supplied from the device (B) in the device (A).

  The device (A) is loaded with a NOx removal catalyst, and exhaust gas NOx is reduced and removed.

As the NOx removal catalyst used in the NOx removal catalyst device (A), a catalyst conventionally used for treating NOx exhaust gas from a fixed generation source can be used. For example, conventionally known NOx removal catalysts disclosed in JP-A-11-342333, JP-A-2003-93880, JP-A-2009-45586 and the like can be used. Specifically, the titanium oxide catalyst that is the urea decomposition catalyst according to the first aspect used in the apparatus (B) can be suitably used.

  According to the exhaust gas treatment apparatus of the present invention, it is possible to reduce the amount of NOx contained in the exhaust gas to 20% or less.

[Example]
Hereinafter, although an example explains, the present invention is not limited by these examples.
[Example 1]
Preparation of catalyst for urea hydrolysis (1) Titanium oxide powder (manufactured by Ishihara Sangyo Co., Ltd .: CTAC115, TiO ₂ : 90% by mass, SiO ₂ : 5% by mass, WO ₃ : 5% by mass, average particle diameter 1 μm, 9.7 kg of specific surface area 102 m ^{2 /} g) and 2.7 kg of silica sol (manufactured by JGC Catalysts & Chemicals Co., Ltd .: catalyst-S, SiO ₂ : 20% by mass) are dispersed in 21.7 kg of water to obtain a solid concentration of 30 A slurry (1) of titanium oxide carrier for weight% was prepared.

  Separately, 1.2 kg of ammonium metavanadate powder (AMV), 0.8 kg of ammonium paratungstate powder (APT) were mixed with 0.8 kg of monoethanolamine solution (MEA) and 2.7 kg of water to prepare a dispersion, Subsequently, the solution was heated to prepare a dissolution solution (1) of active metal component powder having a solid content concentration of 30% by weight.

  Next, the active metal component-dissolved solution (1) was mixed with the titanium oxide support slurry (1) at a weight ratio of 10: 1, and then stirred for 3 hours to prepare a catalyst preparation slurry (1 ) Was prepared.

The catalyst component ratios at that time were TiO ₂ : 77.5% by mass, SiO ₂ : 9.1% by mass, WO ₃ : 8.2% by mass, and V ₂ O ₅ : 5.2% by mass.

  Next, a corrugated base material (manufactured by Seibu Giken Co., Ltd .: main component: ceramics, shape: corrugated honeycomb laminate (shape: 120 cpsi, 30 mm □, 40 mmL, P = 4.2 mm, H = 2.5 mm) After being immersed in the slurry for catalyst preparation (1) for 15 minutes, it was lifted and then dried at 110 ° C. for 12 hours.

  Thereafter, in the same manner as above, immersion and drying were repeated three times, and then calcined at 500 ° C. for 5 hours to prepare a catalyst for urea hydrolysis (1).

  The amount of catalyst layer formed per unit weight of the corrugated substrate of the obtained catalyst for hydrolysis of urea (1) was 400% by weight.

  Further, the composition of the catalyst layer was analyzed, the specific surface area and the pore volume were measured, and the results are shown in the table.

A device (C) and a device (A) having a supercharger downstream of the exhaust gas line of a NOx removal reaction diesel engine (rated output: 10,000 kw), and containing the device (B) downstream of the supercharger ) Was connected.

  The apparatus (B) is a prismatic reactor (50 mm □, 60 mmL) which is filled with 37 ml of the urea hydrolysis catalyst (1) and does not come into contact with exhaust gas. A device (A) provided downstream of the exhaust gas line is filled with 7.78 liters of honeycomb type NOx removal catalyst (1) (manufactured by JGC Catalysts & Chemicals Co., Ltd .: SNR-5, 58 cpsi, 150 mm □, 350 mmL). And a prismatic reactor (250 mm □, 500 mmL) provided with a heating device (electric furnace). A flow model of this NOx removal test apparatus is shown in FIG.

  Subsequently, A heavy oil (sulfur concentration: 0.4 mass%, aromatic concentration 28 mass%, residual carbon concentration 0.3 mass%) was used as the fuel, and the engine was operated. Next, the engine speed was fixed at 120 rpm, a part of the exhaust gas (910 NL / min) was supplied from the device (C) to the downstream device (A), and the remaining exhaust gas was exhausted outside the system. At this time, the temperature of the exhaust gas at the supercharger outlet was 240 ° C.

  The apparatus (B) was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr. Further, the temperature of the catalyst layer of the NOx removal catalyst (1) of the apparatus (A) was adjusted to be constant at 270 ° C. After 2 hours from the start of operation, the temperature of the catalyst layer of the apparatus (B) became constant at 240 ° C. The ammonia gas at the outlet of the apparatus (B) at this time was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table.

  The production rate (%) of ammonia was expressed as 10 minutes of ammonia production (equal amount) / 10 minutes of supplied urea (equal amount) × 100.

On the other hand, the NOx gas concentration at the outlet of the device (A) was analyzed with a NOx analyzer (manufactured by Yanaco Co., Ltd .: ECL-88AO) and shown together with the NOx removal rate in the table. Further, after 300 hours of operation, ammonia concentration, ammonia generation rate, NOx gas concentration, and NOx removal rate were measured in the same manner, and the results are shown in the table.
[Example 2]
NOx removal reaction In Example 1, NOx removal was performed in the same manner except that low-sulfur A heavy oil (sulfur concentration: 0.05 mass%, aromatic concentration 14 mass%, residual carbon concentration 0.2 mass%) was used as the fuel. Reaction was performed. The table shows the NOx gas concentration and NOx removal rate at the outlet of the apparatus (A).
[Example 3]
NOx removal reaction In Example 1, the NOx removal reaction was performed in the same manner except that C heavy oil (sulfur concentration: 2.5 mass%, aromatic concentration 30 mass%, residual carbon concentration 2 mass%) was used as the fuel oil. It was. The table shows the NOx gas concentration and NOx removal rate at the outlet of the apparatus (A).
[Example 4]
NOx removal reaction In Example 1, the engine speed was adjusted to 177 rpm, a part of the exhaust gas (910 NL / min) was supplied to the downstream device (A), and the remaining exhaust gas was exhausted outside the system.

  The apparatus (B) was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr. The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to a constant 270 ° C. After 2 hours from the start of operation, the temperature of the catalyst layer of the device (B) became constant at 280 ° C. Subsequently, a NOx removal reaction was performed in the same manner.

Ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table. Further, the table shows the NOx gas concentration and the NOx removal rate at the outlet of the apparatus (A).
[Example 5]
In NOx removal reaction Example 1, the engine speed was adjusted to 55 rpm, a part of exhaust gas (910 NL / min) was supplied to the downstream device (A), and the remaining exhaust gas was exhausted outside the system.

  The apparatus (B) was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr. The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to 220 ° C. Two hours after the start of operation, the temperature of the catalyst layer of the device (B) became constant at 230 ° C., and then the NOx removal reaction was performed.

Ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table. Further, the table shows the NOx gas concentration and the NOx removal rate at the outlet of the apparatus (A).
[Example 6]
Preparation of Urea Hydrolysis Catalyst (2) A urea hydrolysis catalyst (2) was prepared in the same manner as in Example 1 except that the corrugated substrate was immersed twice in the catalyst preparation slurry (1).

  The amount of catalyst layer formed per unit weight of the corrugated substrate of the obtained catalyst for hydrolysis of urea (2) was 200% by mass.

Further, the composition of the catalyst layer was analyzed, the specific surface area and the pore volume were measured, and the results are shown in the table.
NOx removal reaction In Example 1, a NOx removal test apparatus was prepared in the same manner except that the urea hydrolysis catalyst (2) was charged.

  Subsequently, A heavy oil (sulfur concentration: 0.4 mass%, aromatic concentration 28 mass%, residual carbon concentration 0.3 mass%) was used as the fuel, and the engine was operated. Next, the engine speed was fixed at 120 rpm, a part of the exhaust gas (910 NL / min) was supplied to the downstream device (A), and the remaining exhaust gas was exhausted outside the system.

  The apparatus (B) was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr. The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to a constant 270 ° C. After 2 hours from the start of operation, the temperature of the catalyst layer of the apparatus (B) became constant at 240 ° C. Subsequently, a NOx removal reaction was performed in the same manner.

Ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table. Further, the table shows the NOx gas concentration and the NOx removal rate at the outlet of the apparatus (A).
[Example 7]
Preparation of Urea Hydrolysis Catalyst (3) A urea hydrolysis catalyst (3) was prepared in the same manner as in Example 1 except that the corrugated substrate was immersed 6 times in the catalyst preparation slurry (1).

  The catalyst layer formation amount per unit weight of the corrugated substrate of the obtained catalyst for urea hydrolysis (3) was 600% by mass.

Further, the composition of the catalyst layer was analyzed, the specific surface area and the pore volume were measured, and the results are shown in the table.
NOx removal reaction In Example 1, a NOx removal test apparatus was prepared in the same manner except that the catalyst for urea hydrolysis (3) was charged.

  Subsequently, A heavy oil (sulfur concentration: 0.4 mass%, aromatic concentration 28 mass%, residual carbon concentration 0.3 mass%) was used as the fuel, and the engine was operated. Next, the engine speed was fixed at 120 rpm, a part of the exhaust gas (910 NL / min) was supplied to the downstream device (A), and the remaining exhaust gas was exhausted outside the system.

  The apparatus (B) was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr. The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to a constant 270 ° C. After 2 hours from the start of operation, the temperature of the catalyst layer of the apparatus (B) became constant at 240 ° C. Subsequently, a NOx removal reaction was performed in the same manner.

Ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table. Further, the table shows the NOx gas concentration and the NOx removal rate at the outlet of the apparatus (A).
[Example 8]
A device (C) and a device (A) that have a supercharger downstream of the exhaust gas line of a NOx removal reaction diesel engine (rated output: 10,000 kW) and that contain the device (B) downstream of the supercharger Was connected to the catalyst device.

  The apparatus (B) is filled with 37 ml of honeycomb type NOx removal catalyst (4) (manufactured by JGC Catalysts & Chemicals Co., Ltd .: SNR-5, 58 cpsi, 33 mm □, 34 mmL) as the urea hydrolysis catalyst (4), It is a prismatic reactor (180 mm □, 500 mmL) that does not come into contact with exhaust gas. The apparatus (A) provided downstream is filled with a honeycomb type NOx removal catalyst (1) (manufactured by JGC Catalysts & Chemicals Co., Ltd .: SNR-5, 58 cpsi, 150 mm □, 350 mmL) in the exhaust gas line, and a heating device It is a prismatic reactor (250 mm □, 500 mmL) provided with (electric furnace).

  Subsequently, A heavy oil (sulfur concentration: 0.4 mass%, aromatic concentration 28 mass%, residual carbon concentration 0.3 mass%) was used as the fuel, and the engine was operated. Next, the engine speed was fixed at 120 rpm, a part of the exhaust gas (910 NL / min) was supplied to the downstream device (A), and the remaining exhaust gas was exhausted outside the system.

  The apparatus (B) was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr. The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to a constant 270 ° C. After 2 hours from the start of operation, the temperature of the catalyst layer of the apparatus (B) became constant at 240 ° C. Subsequently, a NOx removal reaction was performed in the same manner.

Ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table. Further, the table shows the NOx gas concentration and the NOx removal rate at the outlet of the apparatus (A).
[Example 9]
Preparation of catalyst for urea hydrolysis (5) A slurry for catalyst preparation (1) having a solid content of 30% by mass was prepared in the same manner as in Example 1. This was spray-dried with a spray dryer under conditions of hot air inlet temperature of 300 to 320 ° C. and outlet temperature of 120 to 130 ° C. to form powder. The average particle diameter of the obtained powder was 65 μm, and the water content was 24.5% by mass.

  1.32 Kg of this powder was put into a high-speed stirring powder mixer (Mitsui Mining Co., Ltd .: Henschel mixer, FM-20C / I type), and 0.47 Kg of water in which 30 g of crystalline cellulose was dissolved in advance was added and mixed well. The water content was adjusted to 44.2% by mass.

After adjusting the water content, it was formed into pellets using a downward roll type extruder (Fuji Paudal Co., Ltd .: Disc pelleter, F-5 (PV-S) / 11-175 type). At this time, first, extrusion was performed once with an extruder nozzle diameter of 3 mmφ, and then extrusion was performed once with a nozzle diameter of 1.5 mmφ to form pellets. At this time, the length of the pellet was relatively uniform, and the average length was 1.8 mm. The obtained pellets having a diameter of 1.5 mmφ were dried at 130 ° C. for 24 hours and then calcined at 530 ° C. for 3 hours to obtain a pellet-like catalyst for urea hydrolysis (5). The pellet-shaped urea hydrolysis catalyst (5) had an average diameter of 1.5 mmφ and an average length of 1.7 mm. Further, the composition of the catalyst layer was analyzed, the specific surface area and the pore volume were measured, and the results are shown in the table.
A catalyst device in which the device (C) and the device (A) are connected is provided downstream of the exhaust gas line of the NOx removal reaction diesel engine (rated output: 10,000 kW).

  The apparatus (B) is a prismatic reactor (180 mm □, 500 mmL) that is charged with 74 g of pellet-shaped urea hydrolysis catalyst (5) as a urea hydrolysis catalyst (5) and does not come into contact with exhaust gas. is there. The apparatus (A) provided downstream of the exhaust gas line is filled with a honeycomb type NOx removal catalyst (1) (manufactured by JGC Catalysts & Chemicals Co., Ltd .: SNR-5, 58 cpsi, 150 mm □, 7.78 liters). , A prismatic reactor (250 mm □, 500 mmL) provided with a heating device (electric furnace).

  Subsequently, A heavy oil (sulfur concentration: 0.4 mass%, aromatic concentration 28 mass%, residual carbon concentration 0.3 mass%) was used as the fuel, and the engine was operated. Next, the engine speed was fixed at 120 rpm, a part of the exhaust gas (910 NL / min) was supplied to the downstream device (A), and the remaining exhaust gas was exhausted outside the system.

  Next, the apparatus (B) was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr. The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to a constant 270 ° C. After 2 hours from the start of operation, the temperature of the catalyst layer of the apparatus (B) became constant at 240 ° C. Subsequently, a NOx removal reaction was performed in the same manner.

Ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table. Further, the table shows the NOx gas concentration and the NOx removal rate at the outlet of the apparatus (A).
[Example 10]
There is a supercharger downstream of the exhaust gas line of the NOx removal reaction diesel engine (rated output: 870 kW), and the device (C) and device (A) containing the device (B) are connected downstream of the supercharger. A catalytic device was provided.

  The apparatus (B) is a prismatic reactor (50 mm □, 60 mmL) filled with 37 ml of the same urea hydrolysis catalyst (1) as in Example 1 and without contact with the exhaust gas. The apparatus (A) provided downstream of the exhaust gas line is filled with a honeycomb type NOx removal catalyst (1) (manufactured by JGC Catalysts & Chemicals Co., Ltd .: SNR-5, 58 cpsi, 150 mm □, 7.78 liters). , A prismatic reactor (250 mm □, 500 mmL) provided with a heating device (electric furnace).

  Next, A heavy oil (sulfur concentration: 0.8 mass%, aromatic concentration 28 mass%, residual carbon concentration 0.3 mass%) was used as the fuel, and the engine was operated. Next, the engine speed was fixed at 177 rpm, a part of the exhaust gas (910 NL / min) was supplied to the downstream device (A), and the remaining exhaust gas was exhausted outside the system.

The apparatus (B) was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr. The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to a constant 270 ° C. After 12 hours from the start of operation, the temperature of the catalyst layer of the apparatus (B) became constant at 240 ° C. Next, ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table.
[Comparative Example 1]
NOx removal reaction Diesel engine (displacement: 2000cc) downstream of the exhaust gas line is a turbocharger, and the urea hydrolysis catalyst (1) is filled downstream of the turbocharger, and the exhaust gas is a prismatic reaction. (50mm □, 60mmL) (Equipment (B)), NOx removal catalyst (1) 7.78 liters filled in the exhaust gas line downstream of it, and prismatic reactor with heating device (electric furnace) A NOx removal test apparatus (apparatus (A)) provided with (250 mm □, 800 mmL) was prepared.

  A flow model of this NOx removal test apparatus is shown in FIG.

  Subsequently, A heavy oil (sulfur concentration: 0.4 mass%, aromatic concentration 28 mass%, residual carbon concentration 0.3 mass%) was used as the fuel, and the engine was operated. Subsequently, the engine speed was fixed at 120 rpm, a part of the exhaust gas (910 NL / min) was supplied from the device (B) to (A), and the remaining exhaust gas was exhausted outside the system.

  On the other hand, the apparatus (B) was operated while supplying urea water having a concentration of 25 mass% at a constant rate of 295 g / Hr. The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to a constant 270 ° C. After 2 hours from the start of operation, the temperature of the catalyst layer of the non-isolated device (B) became constant at 240 ° C. Subsequently, NOx removal reaction was performed.

  Ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table. Further, the table shows the NOx gas concentration and the NOx removal rate at the outlet of the apparatus (A).

Further, after 300 hours of operation, ammonia concentration, ammonia generation rate, NOx gas concentration, and NOx removal rate were measured in the same manner, and the results are shown in the table.
[Reference example]
NOx removal reaction Diesel engine (displacement: 2000cc) A prismatic reactor (150 mm) having a supercharger downstream of the exhaust gas line and filled with 7.78 liters of NOx removal catalyst (1) downstream of the supercharger (□, 350 mmL) (apparatus (A)) was provided, and ammonia gas generated by decomposing urea from the outside of the exhaust gas line was introduced into the apparatus (A).

  Ammonia gas was provided outside, filled with the catalyst for urea hydrolysis (1), and produced by a prismatic reactor (50 mm □, 60 mmL) (apparatus (B)).

  A flow model of this NOx removal test apparatus is shown in FIG.

  Subsequently, A heavy oil (sulfur concentration: 0.4 mass%, aromatic concentration 28 mass%, residual carbon concentration 0.3 mass%) was used as the fuel, and the engine was operated. Next, the engine speed was fixed at 120 rpm, a part of the exhaust gas (910 NL / min) was supplied to the downstream device (A), and the remaining exhaust gas was exhausted outside the system.

  The apparatus (B) in which the temperature of the catalyst layer was adjusted to 240 ° C. was operated while supplying urea water having a concentration of 25% by mass at a constant rate of 295 g / Hr, and the generated ammonia gas was charged into the apparatus (A). The temperature of the catalyst layer of the NOx removal catalyst (1) was adjusted to 270 ° C. to carry out the NOx removal reaction. After 2 hours from the start of operation, ammonia gas at the outlet of the apparatus (B) was collected for 10 minutes, the ammonia concentration was measured, the ammonia production rate was determined, and the results are shown in the table. Further, the table shows the NOx gas concentration and the NOx removal rate at the outlet of the apparatus (A).

Claims (11)

A device (A) for selective reduction of NOx in exhaust gas, which is installed in the exhaust gas system of marine internal combustion engines using heavy oil as fuel, and NOx removal by hydrolysis of urea on the upstream side of the device (A) It consists of a device (C) containing a urea hydrolysis device (B) as a working gas,
The device (B) includes urea water and air input means, and a urea hydrolysis catalyst, and is provided so as not to come into contact with exhaust gas in the device (C).
An exhaust gas treatment apparatus for a ship, characterized in that the exhaust gas passes through the apparatus (C) and is in contact with the NOx removal gas supplied from the apparatus (B) in the apparatus (A).   The exhaust gas treatment apparatus for a ship according to claim 1, wherein a supercharger is provided upstream of the apparatus (C) containing the apparatus (B).   3. The exhaust gas treatment apparatus for a ship according to claim 1, wherein the rated rotational speed of the internal combustion engine is in a range of 50 to 250 rpm.   The urea decomposition catalyst of the apparatus (B) is a titanium oxide-based catalyst, and the titanium oxide-based catalyst has V, W, Mo, Cr, Mn, Fe, Ni, Cu, Ag, 2. The marine exhaust gas treatment apparatus according to claim 1, wherein at least one metal or metal oxide selected from the group consisting of Au, Pd, Y, Ce, Nd, In, and Ir is supported.   The titanium oxide-based support is titanium oxide or a titanium oxide composite oxide containing at least one oxide selected from Si, W, Mo, Zr, and Ba together with titanium oxide. 4. A marine exhaust gas treatment apparatus according to 4.   The marine exhaust gas treatment apparatus according to claim 4 or 5, wherein the titanium oxide-based catalyst is a honeycomb-shaped molded body, a film-shaped molded body, a corrugated molded body, or a granular molded body.   The urea decomposition catalyst of the apparatus (B) is a zeolitic catalyst, and the zeolitic catalyst is a honeycomb-shaped molded body, a film-shaped molded body, a corrugated molded body, or a granular molded body. 4. A marine exhaust gas treatment apparatus according to 4.   The urea decomposition catalyst of the apparatus (B) is a catalyst in which metal oxide fine particles adhere to a conductive honeycomb substrate, corrugated substrate or network support, and the metal oxide particles are Mg, Ca, Ba One or more metal oxides selected from the group consisting of: La, Ce, Ti, Zr, V, Cr, Mo, W, Mn, Zn, Al, Si, P, Sb, Cu, Fe, Ru, Co, Re The marine exhaust gas treatment device according to claim 1 or 4, wherein the marine exhaust gas treatment device is made of a material.   The marine exhaust gas treatment apparatus according to claim 8, wherein the base material of the urea decomposition catalyst of the device (B) is a corrugated base material.   5. The ship exhaust gas treatment apparatus according to claim 1, wherein a reaction temperature when decomposing urea of the apparatus (B) is in a range of 150 to 280 ° C. 6.   The apparatus (A) includes a NOx removal catalyst, the catalyst is a titanium oxide-based catalyst, and the titanium oxide-based catalyst is added to the titanium oxide-based support as active metal components V, W, Mo, Cr, Mn, Fe, Ni. The exhaust gas treatment apparatus for a marine vessel according to claim 1, wherein one or more metals selected from the group consisting of Cu, Ag, Au, Pd, Y, Ce, Nd, In, and Ir are supported. .