JP2009056410A - Waste-gas treatment catalyst for ship and waste-gas treatment method for ship - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste-gas treatment catalyst for a ship and a waste-gas treatment method for a ship which effectively use the catalyst in a limited space such as a ship inside so that the treatment efficiency of the catalyst and the durability for a poisoning substance in a waste gas are improved. <P>SOLUTION: The waste-gas treatment catalyst is a honeycomb type catalyst having a thickness of a honeycomb inner wall of 0.10-0.44 mm, wherein a honeycomb has preferably 1,600-10,000 cells/150 mm<SP>N</SP>(cells/150 mm<SP>N</SP>shows a cell number per a square of side 150 mm). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a ship exhaust gas treatment catalyst and a ship exhaust gas treatment method.

  There is no full-scale regulation for ship exhaust gas treatment, and it is only suggested that the exhaust gas treatment is simply described that it can be treated using a catalyst. There are only various proposals for the installation of the exhaust gas under the conditions such as special conditions of the ship, pitching of the ship, prevention of damage to the catalyst due to rolling, and limited space.

  As a method for removing nitrogen oxides in exhaust gas, nitrogen oxides (NOx, etc.) in exhaust gas are catalytically reduced on a denitration catalyst using a reducing agent such as ammonia or urea, and decomposed into harmless nitrogen and water. A selective catalytic reduction (SCR) process is common.

As a nitrogen oxide removing catalyst (denitration catalyst) applied to this, a titanium-vanadium catalyst is well known (Japanese Patent Laid-Open No. 10-235206).
One of the uses of such a denitration catalyst is, for example, treatment of combustion exhaust gas generated from a ship, but these exhaust gas purification apparatuses are used in ships where the catalyst itself becomes too large and space is limited. It is difficult. In addition, heavy fuel oil C is used as marine fuel, so that the catalyst is easily poisoned due to a large amount of sulfur and dust in the exhaust gas.

  The previously known denitration catalysts described above have excellent removal performance, but depending on the exhaust gas conditions such as containing a lot of deteriorating components, sufficient treatment performance may still not be exhibited. Development of a nitrogen oxide removal catalyst having high performance is desired.

Japanese Patent Laid-Open No. 10-235206

  An object of the present invention is to effectively use a catalyst in a limited space in a ship, and to improve the processing efficiency of the catalyst and improve the durability of exhaust gas against poisonous substances. Furthermore, by using the catalyst, it is possible to obtain an improvement in catalytic activity due to an increase in diffusion efficiency which is larger than the increase in catalytic activity due to an increase in the geometric surface area of the honeycomb itself.

The present inventor has intensively studied to solve the above-mentioned problems, and repeated various estimations and experiments. As a result, the use of a honeycomb type catalyst having a honeycomb inner wall thickness of 0.10 to 0.44 mm as a catalyst for ship exhaust gas treatment makes it difficult to contain many deterioration components. The present inventors completed the present invention by confirming that excellent catalyst performance can be exhibited even under exhaust gas conditions, and that nitrogen oxides in exhaust gas can be effectively removed, and that the above problems can be solved easily and easily. did. Preferably, it is a ship exhaust gas treatment catalyst (cell / 150 mm ^□ represents the number of cells per square with a side of 150 mm) using a honeycomb of 1600 to 10,000 cells / 150 mm ^□ . More preferably, the specific surface area (BET specific surface area) of the catalyst is 1 to 200 m ² / g. The catalyst composition of the catalyst is at least one selected from the group consisting of titanium, silicon, vanadium, molybdenum, and tungsten.

  The exhaust gas treatment method according to the present invention is characterized by treating exhaust gas containing nitrogen oxides using the exhaust gas treatment catalyst of the present invention.

  According to the exhaust gas treatment catalyst and the exhaust gas treatment method using the same according to the present invention, nitrogen oxides such as NOx in the exhaust gas can be removed very efficiently and sufficiently.

  By using the catalyst, it is possible to obtain an improvement in catalytic activity due to an increase in diffusion efficiency which is larger than an increase in catalytic activity simply due to an increase in the geometric surface area of the honeycomb itself.

The first invention according to the present invention uses a honeycomb type catalyst having a honeycomb inner wall thickness of 0.10 to 0.44 mm as a catalyst for ship exhaust gas treatment. It has been found that it can exhibit excellent catalytic performance even under severe exhaust gas conditions such as containing a large amount of nitrogen, and can effectively remove nitrogen oxides in exhaust gas, and confirms that the above problems can be solved all at once. Thus, the present invention has been completed. Preferably, it is a ship exhaust gas treatment catalyst using a honeycomb of 1600 to 10,000 cells / 150 mm ^□ (cell / 150 mm ^□ represents the number of cells per square of 150 mm on a side). More preferably, the specific surface area (BET specific surface area) of the catalyst is 1 to 200 m ² / g. The catalyst composition of the catalyst is at least one selected from the group consisting of titanium, silicon, vanadium, molybdenum, and tungsten.

  2nd invention concerning this invention is a processing method of the ship exhaust gas characterized by processing the exhaust gas emitted from a marine engine using the said catalyst. Preferably, the exhaust gas contains sulfur oxide, nitrogen oxide (NOx), and dust. Hereinafter, the first invention and the second invention will be described in detail.

The honeycomb inner wall thickness is 0.10 to 0.44 mm, preferably 0.20 to 0.44 mm. This is because, within this range, it is possible to suppress oxidation of SO ₂ that is a sulfur content contained in the exhaust gas.

The honeycomb has 1600 to 10,000 cells / 150 mm ^□ , preferably 1600 to 4900 cells / 150 mm ^□ . When it exceeds 10,000 cells / 150 mm ^□ , the catalyst is likely to be clogged by dust components in the exhaust gas, and the vibration resistance is reduced, so that it is brittle in strength and easily chipped. This is because when it is less than 1600 cells / 150 mm ^□ , the geometric surface area of the catalyst decreases and the denitration rate decreases. By having such a cell, the catalyst activity can be improved by increasing the diffusion efficiency which is larger than the increase in catalyst activity simply by increasing the geometric surface area of the honeycomb itself.

  The length of the honeycomb is 200 to 2000 mm, preferably 300 to 1000 mm. The honeycombs can be used alone or in a plurality in series or in parallel.

The specific surface area (BET specific surface area) of the catalyst is preferably 1 to 200 m ² / g.

  The catalyst composition of the catalyst is preferably at least one selected from the group consisting of titanium, silicon, vanadium, molybdenum, and tungsten. In use, individual single oxides, mixtures of individual oxides, In addition to the use of complex oxides, the use ratios between elements can be changed and used. These can be appropriately changed depending on the components of the exhaust gas. Among these, the preferred composition is an oxide-converted mass ratio of each element, 10 to 50% by mass of silicon oxide, 10 to 90% by mass of titanium oxide, 1 to 25% by mass of tungsten oxide, and vanadium oxide. It is preferable that a thing is 0.1-15 mass% (a total of 100 mass%).

  As the feedstock of the catalyst, the silicon source can be appropriately selected from inorganic silicon compounds such as colloidal silica, water glass, fine particle silicon and silicon tetrachloride, and organic silicon compounds such as tetraethyl silicate. As the titanium source, any inorganic or organic compound can be used as long as it can be baked to produce a titanium oxide. For example, an inorganic titanium compound such as titanium tetrachloride and titanium sulfate, titanium oxalate, tetraisopropyl, etc. An organic titanium compound such as titanate can be used. The tungsten source, vanadium source, and molybdenum source may be any inorganic or organic compound as long as they generate oxides by firing, such as hydroxides, ammonium salts, and oxalic acid containing each metal. A salt, halide, sulfate, nitrate or the like can be used as appropriate.

  The method for preparing the catalyst is not particularly limited, and conventionally known production techniques are applied. Specifically, (1) After dissolving the compounds as raw materials for various catalyst components in an aqueous medium, by adding ammonia or the like to the liquid, the hydroxide of each catalyst component is obtained as a precipitate, and filtered, A method of obtaining a catalyst by washing, drying and baking the hydroxide (precipitation method), (2) depositing each catalyst component compound as an aquatic liquid on an oxide having a high surface area, and then drying and baking There is a method for obtaining a catalyst (deposition method), and (3) a method for obtaining a catalyst by sufficiently kneading each catalyst component compound in an aqueous medium, followed by drying and firing (kneading method). The catalyst obtained by (1) can be formed into a honeycomb by a known method to obtain an exhaust gas treatment catalyst. (4) A method (impregnation method) of obtaining an exhaust gas catalyst by coating a honeycomb-shaped carrier with a catalyst component can also be employed. Hereinafter, a method for preparing a catalyst will be specifically described using a composite oxide of titanium and silicon (Ti-Si composite oxide) as an example.

  The preparation of the Ti—Si composite oxide is not particularly limited, and conventionally known production techniques are applied. Specifically, preparation methods such as a precipitation method, a deposition method, and a kneading method can be applied.For example, a sulfuric acid aqueous solution of titanyl sulfate is neutralized and mixed with an aqueous ammonia solution of silica sol to form a precipitate, and the precipitate is washed. A method of drying at 120 to 250 ° C., adding the dry powder obtained in an aqueous solution of barium nitrate, drying after washing, drying at 300 to 650 ° C.

  Neutralized and mixed aqueous solution of titanyl sulfate with sulfuric acid aqueous solution of fine particle silicon to produce precipitate, washed this precipitate, dried at 120-250 ° C, and then dried powder obtained in aqueous barium nitrate solution Is added, and after washing, drying and baking at 300 to 650 ° C.

This method is carried out as follows. That is, a sulfuric acid aqueous solution of titanyl sulfate containing a predetermined amount of titanium is prepared at a concentration of 1 to 100 g / in terms of titanium oxide. On the other hand, after adding an amount of ammonia necessary for neutralization to an aqueous solution containing a predetermined amount of silica to a concentration of 1 to 100 g / in terms of silica oxide, the aqueous titanyl sulfate solution is gradually neutralized with stirring. Heat is added while removing heat to form a coprecipitation compound composed of titanium and silicon, washed separately, dried at 80 to 250 ° C. for 1 to 10 hours, and pulverized. The obtained TiO ₂ —SiO ₂ dry powder usually contains 0.1 to 8 wt% of sulfur oxide as SO ₄ -2.

As an example of the catalyst preparation method according to the present invention, when TiO ₂ —SiO ₂ , vanadium and tungsten are contained, a predetermined amount of ammonium metavanadate and ammonium paratungstate are dissolved in an aqueous solution of monoethanolamine or oxalic acid. TiO ₂ —SiO ₂ powder prepared in advance by the above method is added to the aqueous solution containing vanadium and tungsten together with a molding aid, mixed and kneaded, and formed into a honeycomb shape with an extrusion molding machine. After the molded product is dried at 50 to 120 ° C., the catalyst can be obtained by calcination at 300 to 650 ° C., preferably 350 to 550 ° C. for 1 to 10 hours, preferably 2 to 6 hours under air flow. As another method, a method in which a powder of TiO ₂ —SiO ₂ is previously formed into a honeycomb shape and fired, and then impregnated with an aqueous solution containing vanadium and tungsten can be employed. It is also possible to use a carrier. As the carrier, for example, alumina, silica, silica alumina, bentonite, diatomaceous earth, silicon carbide, titania, zirconia, magnesia, cordierite, mullite, pumice, activated carbon, inorganic fibers, etc. are used by a kneading method, a supporting method, etc. Can do. Of course, the catalyst preparation method is not limited to these methods.

  The catalyst shape is not limited to the honeycomb shape described above, and a columnar shape, a cylindrical shape, a plate shape, a ribbon shape, a corrugated plate shape, a pipe shape, a donut shape, a lattice shape, and other integrally formed shapes are appropriately selected.

  2nd invention concerning this invention is a processing method of the ship exhaust gas characterized by processing the exhaust gas emitted from a marine engine using the said catalyst. Preferably, the exhaust gas contains sulfur oxide, nitrogen oxide (NOx), and dust.

  The exhaust gas targeted by the catalyst is exhaust gas generated from a marine engine. Preferably, the exhaust gas contains sulfur oxide, nitrogen oxide (NOx), and soot and dust. Specifically, the denitration catalyst produced by the present invention is excellent in the decomposition activity of nitrogen oxides emitted from boilers, incinerators, gas turbines, diesel engines, and various industrial processes, and exhaust gas treatment containing these nitrogen oxides Is preferably used. Further, these exhaust gases generally contain sulfur dioxide, and when the sulfur dioxide is oxidized to sulfur trioxide, problems such as corrosion of the device occur. However, the denitration catalyst of the present invention is sulfur dioxide. Is more preferably used because of its low ability to oxidize to sulfur trioxide.

The composition of the exhaust gas to be treated in which the catalyst of the present invention is used is usually SOx 10 to 2000 ppm, oxygen 1 to 20% by volume, water vapor 5 to 10% by volume, soot 50 to 300 g / Nm ³ and NOx (mainly NO) is contained in an amount of about 100 to 2000 ppm. Normal diesel engine exhaust gas falls within this range, but the gas composition is not particularly limited. This is because the catalyst of the present invention can treat special exhaust gases such as NOx-containing exhaust gas containing no SOx and NOx-containing exhaust gas containing a halogen compound.

  In order to perform denitration using the denitration catalyst produced according to the present invention, the denitration catalyst is brought into contact with exhaust gas in the presence of a reducing agent such as ammonia or urea, and nitrogen oxides in the exhaust gas are reduced and removed. The conditions at this time are not particularly limited, and can be carried out under conditions generally used for this type of reaction. Specifically, it may be appropriately determined in consideration of the type and properties of exhaust gas, the required decomposition rate of nitrogen oxides, and the like.

In the method of the present invention, the space velocity of the exhaust gas in the case of performing the processing of various exhaust gas is usually 100~100000Hr ^-1 (STP), preferably 200~50000Hr ^-1 (STP). When the space velocity is less than 100 Hr ⁻¹ , in general, the processing apparatus becomes too large and becomes inefficient, and when it exceeds 100000 Hr ⁻¹ , the efficiency of decomposition and removal of harmful components in various exhaust gases decreases. There is a fear.

  Moreover, about the temperature of the various waste gas made into a process target, it is preferable that it is 100-500 degreeC, More preferably, it is 150-500 degreeC, More preferably, it is 250-450 degreeC.

  Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the examples unless it is contrary to the spirit of the present invention.

(Example 1)
The Ti—Si composite oxide containing vanadium and tungsten obtained by the above method was molded into the following honeycomb type to form an exhaust gas catalyst, and the denitration rate and SO ₂ oxidation rate were measured at the following gas composition. Each catalyst composition was 7.6% by mass of vanadium oxide, 5.4% by mass of tungsten oxide, 65.8% by mass of titanium oxide (in terms of TiO 2), and 21.2% in terms of silicon oxide (in terms of SiO 2). % By mass. The shape of the exhaust gas catalyst is a honeycomb of 1600 to 4900 cells / 150 mm ^□ (cell / 150 mm ^□ represents the number of cells per square of 150 mm on a side). Other shapes and physical properties of the honeycomb are shown in Table 1. The denitration rate and SO ₂ oxidation rate were determined by the following method. A honeycomb reaction tube with an inner diameter of 38 mm immersed in a molten salt bath was filled with a honeycomb catalyst, and NH ₃ was added to a synthesis gas having the following composition approximated to diesel engine exhaust gas only in the catalyst pores, while = 50 Nm ³ / m ² Hr was introduced into the catalyst layer, and the denitration rate and SO ₂ oxidation rate at a reaction temperature of 350 ° C. were determined.
Gas composition NO 900ppm
SO ₂ 500ppm
O ₂ 15% by volume
H ₂ O 10% by volume
N ₂ residual NH ₃ 900 ppm
The NOx removal rate was determined according to the following equation by measuring the NOx concentration at the inlet and outlet of the catalyst layer with a NOx meter (chemiluminescence type, ECL-88A0 manufactured by YANAKO).
Denitration rate (%) =
(Inlet NOx concentration) − (Outlet NOx concentration) / (Inlet NOx concentration) × 100
The SO ₂ oxidation rate is as follows. First, all SOx in the exhaust gas at the catalyst layer outlet is absorbed in 5% hydrogen peroxide solution for a certain period of time and collected as a sulfuric acid aqueous solution. A part of this is weighed and mixed with isopropyl alcohol. The concentration of total SOx is obtained by titrating with an aqueous barium acetate solution adjusted to a predetermined concentration, and then SO ₃ in the exhaust gas is determined by the method of Goxoyear et al. (H. GOKSφYR, et al., J, Ins Fuel, 35, 177, 1961), the SO ₃ concentration was determined by the above method, and the SO ₂ oxidation rate was determined according to the following formula.
SO ₂ oxidation rate (%) = (outlet SO ₃ concentration) / (total SOx concentration) × 100
The obtained results are shown in Table 1.

脱硝活性比とは、比較例４の排ガス触媒における幾何学的表面積の脱硝率を１としたとき、他の排ガス触媒における幾何学的表面積が比較例４のそれとの増減率に対して脱硝率の増減を示したものである。単純に幾何学的表面積の増加・減少により脱硝率が増加・減少すれば脱硝活性率が１なる。

The denitration activity ratio means that when the denitration rate of the geometric surface area in the exhaust gas catalyst of Comparative Example 4 is 1, the geometric surface area of the other exhaust gas catalyst is the denitration rate relative to the rate of increase / decrease with that of Comparative Example 4 It shows the increase or decrease. If the denitration rate increases / decreases simply by increasing / decreasing the geometric surface area, the denitration activity rate becomes 1.

本発明にかかる触媒の性能が選択性にすぐれていることがわかる。

It can be seen that the performance of the catalyst according to the present invention is excellent in selectivity.

(Examples 2 to 5)
In Example 1, the catalyst was evaluated in the same manner as in Example 1 except that the shape and physical properties of the exhaust gas catalyst were changed. The shape, physical properties and evaluation are shown in Table 2. From the following results, these exhaust gas catalysts according to the present invention have a higher denitration performance (denitration activity ratio) than that obtained by simply increasing the geometric surface area, and have a very low SO ₂ oxidation activity and are good. I understand that there is.

（比較例１〜４）
実施例１において、排ガス触媒の形状・物性を変えた以外は実施例１と同様にして触媒の評価を行った。当該形状、物性及び評価は表３に示す。ハニカム内壁が本発明の範囲外なる排ガス触媒は脱硝活性比が低く幾何学的表面積が少なくなったより以上に活性が低下することが分かった。

(Comparative Examples 1-4)
In Example 1, the catalyst was evaluated in the same manner as in Example 1 except that the shape and physical properties of the exhaust gas catalyst were changed. The shape, physical properties and evaluation are shown in Table 3. It has been found that an exhaust gas catalyst having a honeycomb inner wall outside the scope of the present invention has a lower denitration activity ratio and a lower activity than when the geometric surface area is reduced.

  The present invention is a ship exhaust gas treatment catalyst and a ship exhaust gas treatment method. This is a technique that can be used in fields where it is desired to effectively treat exhaust gas in a system with limited space.

Claims (6)

A marine exhaust gas treatment catalyst characterized by being a honeycomb type catalyst having a honeycomb inner wall thickness of 0.10 to 0.44 mm. The ship exhaust gas treatment catalyst according to claim 1, wherein the honeycomb of 1600 to 10000 cells / 150mm ^{□ according} to claim 1 is used.
(Cell / 150mm ^□ represents the number of cells per square with a side of 150mm) ^2. The ship exhaust gas treatment catalyst according to claim 1, wherein the catalyst according to claim 1 has a specific surface area (BET specific surface area) of 1 to 200 m ² / g. The ship exhaust gas treatment catalyst according to claim 1, wherein the catalyst composition of the catalyst according to claim 1 is at least one selected from the group consisting of titanium, silicon, vanadium, molybdenum, and tungsten. A method for treating ship exhaust gas, comprising treating exhaust gas containing nitrogen oxides generated from a marine engine using the catalyst according to claim 1. The exhaust gas according to claim 5 contains sulfur oxides, nitrogen oxides (NOx), and soot, and a processing method for marine exhaust gas.