JP6368251B2 - Honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas, method for producing the same, and method for treating coal and biomass mixed combustion exhaust gas using the same. - Google Patents

Description

  The present invention relates to a honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas, a production method thereof, and a coal and biomass mixed combustion exhaust gas treatment method using the same.

  Currently, in coal-fired power generation, biomass fuel co-firing is being promoted from the viewpoint of reducing the environmental burden, and a substantial increase in the co-firing rate is also being considered. However, biomass fuel contains a large amount of poisonous substances for the flue gas treatment catalyst, and if the co-firing rate of the biomass fuel is increased, the combustion dust containing a large amount of the poisonous substances causes the loss of the flue gas treatment catalyst. There is a problem of life.

Conventionally, several proposals have been made regarding the above flue gas treatment catalyst.
For example, Patent Document 1 discloses a composition comprising titanium oxide (TiO ₂ ), aluminum sulfate (Al ₂ (SO ₄ ) ₃ ), vanadium (V), and an oxide of molybdenum (Mo) and / or tungsten (W). In this case, vanadium oxoacid salt or vanadyl is contacted with titanium oxide adsorbing sulfate ions and aluminum ions when titanium sulfate is in contact with titanium oxide in an amount of more than 1 wt% and not more than 6 wt% in the presence of water. An exhaust gas purifying catalyst is described in which a salt and an oxo acid or oxo acid salt of molybdenum and / or tungsten are supported in a proportion of more than 0 atom% and 3 atom% or less.

Patent Document 2 discloses titanium (Ti), phosphorus (P) oxide, molybdenum (Mo) and / or tungsten (W), and vanadium (V) oxide, and SiO ₂ / Al ₂ O _3. A catalyst composition comprising a high silica zeolite having a ratio of 20 or more, comprising: (1) titanium oxide and phosphoric acid or ammonium salt of phosphoric acid in an amount of more than 1 and not more than 15 wt% as H ₃ PO ₄ with respect to titanium oxide (2) Molybdenum (Mo) and / or tungsten (W) oxo acid or oxo acid salt and vanadium (V) oxo acid salt or vanadyl salt exceeding 0 and not more than 8 atom%, and (3) high silica zeolite Describes an exhaust gas denitration catalyst that is kneaded, dried and calcined in the presence of water under a condition of more than 0 and not more than 20 wt% with respect to titanium oxide.

Patent Document 3 discloses that titanium oxide and phosphoric acid or ammonium phosphate of more than 1 and not more than 15% by weight as H ₃ PO _{4 with} respect to titanium oxide are brought into contact with each other in the presence of water and phosphorous is applied to the surface. Titanium oxide adsorbed with acid ions is mixed with an oxo acid or oxo acid salt of molybdenum (Mo) and / or tungsten (W) and an oxo acid salt or vanadyl salt of vanadium (V) exceeding 8 atoms. A catalyst for purifying exhaust gas is described which is characterized in that it is supported at less than or equal to%.

  Furthermore, Patent Document 4 discloses a catalyst for reducing and removing nitrogen oxides in exhaust gas containing dust with ammonia, wherein the cracks on the catalyst surface are filled with inert carrier particles. Catalysts for use are described.

JP 2012-035216 A JP 2012-055810 A JP 2011-161364 A JP 2013-000615 A

  Deactivation of the above flue gas treatment catalyst is likely to be caused by calcium. Calcium, which is one of poisoning components, is easy to concentrate in the combustion dust and has a high ratio in the dust. Therefore, salting out tends to cause catalyst deactivation.

  On the other hand, Patent Document 1 describes a purification method in which mixed combustion exhaust gas of biomass and coal is treated using ammonia as a reducing agent, but catalytic poisoning substances (mainly potassium) are catalyzed by adding aluminum sulfate. The trap is to prevent chemical active point poisoning of the catalyst in the inside, and resistance to physical deactivation such as calcium blocking the catalyst pores or covering the catalyst surface Is not taken into account, and it is thought that deterioration occurs in an environment using biomass fuel with a high amount of calcium.

  In addition, Patent Document 2 mentions prevention of deterioration of catalyst poisonous substances such as arsenic, phosphorus, and potassium, and potassium is cited as a cause of deterioration due to biomass fuel. It is a technique of preventing active site poisoning by adding zeolite that does not pass ammonia gas, and in the same way as in Patent Document 1, it deactivates physically covering catalyst pores and catalyst surface. There is no effect on this, and it is thought that deterioration occurs in an environment rich in calcium.

  Further, Patent Document 3 describes a purification method for treating mixed combustion exhaust gas of biomass and coal with ammonia as a reducing agent, but is a potassium trap by addition of phosphoric acid. Similarly, it is an active point poisoning prevention mechanism of the catalyst, and no consideration is given to deactivation that physically covers the catalyst pores or the catalyst surface.

  Furthermore, Patent Document 4 describes a catalyst for treating exhaust gas containing dust, and a treatment method. Inactual deactivation is prevented by filling a catalyst crack in advance to prevent dust from entering. There are cases where dust adheres without cracks, for example, by being caught by the catalyst surface irregularities. In addition, fine dust may enter gaps in the crack sealing material. Since the crack is sealed, the surface area may be reduced and the catalyst performance itself may be lowered. Therefore, the catalyst may have a long life but a low performance.

  Thus, conventionally, there has been no effective measure against deactivation of the flue gas treatment catalyst used when co-firing biomass fuel containing a large amount of calcium.

  An object of the present invention is to solve the above problems. That is, the present invention is a honeycomb catalyst for treating coal and biomass co-fired exhaust gas, a method for producing the same, and coal and biomass using the same, which are difficult to deactivate even when used when co-firing biomass fuel containing a large amount of calcium. An object of the present invention is to provide a mixed combustion exhaust gas treatment method.

  The present inventor diligently studied to solve the above-mentioned problems, and by trapping the calcium salt which is a pore-occluding type poisonous substance by forming a large opening (deposit hole) on the catalyst surface, The present inventors have found that it is possible to prevent the deposit hole from being blocked and to suppress the deactivation of the catalyst due to the salting out of calcium.

The present invention includes the following (i) to (iv).
(I) a honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas, comprising an inorganic oxide carrier containing Ti, Si and W, and a metal component containing at least one selected from V and Mo,
It has a deposit hole with a width of 4 to 20 μm and a depth of 20 to 300 μm, which is a physical deposition hole for calcium salt, and the ratio of the total area of the deposit hole openings to the surface area of the inner wall of the catalyst is 5 to 10%. And
The difference (SA _BET -SA _Hg ) between the specific surface area (SA _BET ) by the BET method and the specific surface area (SA _Hg ) exhibited by the catalyst pores of 5 nm to 5 μm by the mercury intrusion porosimetry method is 15 to 25 m ² / g A honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas, characterized by being in the range.
(Ii) Coal according to (i) above, wherein the honeycomb catalyst has a honeycomb cell with a thickness of 1 mm and an opening of 6.4 mm, and has a compressive strength of 50 to 300 N / cm ² Honeycomb catalyst for biomass mixed combustion exhaust gas treatment.
(Iii) (1) dehydrating a slurry containing Ti and W and firing to obtain a Ti—W composite oxide;
(2) dehydrating a slurry containing Ti, W and Si and firing to obtain a Ti—W—Si composite oxide;
(3) The ratio of the mass of the Ti—W composite oxide to the total mass of the Ti—W composite oxide and Ti—W—Si composite oxide obtained in the previous step (of the Ti—W composite oxide). The mixture was added after adding water so that the mass / (mass of Ti—W composite oxide + mass of Ti—W—Si composite oxide) × 100 (%)) was 5 to 80% by mass. A process of extruding, molding, drying and firing,
A method for producing a honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas as described in (i) or (ii) above.
(Iv) contacting the coal and biomass mixed combustion exhaust gas treatment honeycomb catalyst described in (i) or (ii) above with a coal mixed combustion exhaust gas containing a biomass fuel of more than 0% and 50% or less on a calorie basis. A coal and biomass mixed combustion exhaust gas treatment method characterized by the above.

  ADVANTAGE OF THE INVENTION According to this invention, it is hard to deactivate even when it is used when co-firing biomass fuel containing a lot of calcium. A mixed combustion exhaust gas treatment method can be provided.

3 is a SEM image of the surface of the catalyst of Example 2. 4 is a SEM image of the surface of a catalyst of Comparative Example 2. It is the schematic for demonstrating the measuring method of a deposit hole area ratio. It is the schematic for demonstrating the measuring method of the deposit hole depth. It is another schematic diagram for demonstrating the measuring method of deposit hole depth. It is a SEM image of the surface of the catalyst of Example 2 after an accelerated deterioration test. It is a SEM image of the surface of the catalyst of the comparative example 2 after an accelerated deterioration test. It is the schematic for demonstrating the side-hand method of compressive strength.

<Catalyst of the present invention>
The present invention will be described.
The present invention is a honeycomb catalyst for treating coal and biomass co-fired exhaust gas, comprising an inorganic oxide support containing Ti, Si and W and a metal component containing at least one selected from V and Mo, A deposit hole having a width of 4 to 20 μm and a depth of 20 to 300 μm, which is a physical deposition hole, and the ratio of the total area of the deposit hole openings to the surface area of the inner wall of the catalyst is 5 to 10%; The difference (SA _BET -SA _Hg ) between the specific surface area (SA _BET ) by the BET method and the specific surface area (SA _Hg ) exhibited by the catalyst pores of 5 nm to 5 μm by the mercury intrusion porosimetry method is 15 to 25 m ² / g A honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas, which is characterized by being in the range.
Such a honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas is hereinafter also referred to as “the catalyst of the present invention”.

  The catalyst of the present invention is a honeycomb-like structure containing the inorganic oxide support and the metal component, and has a deposit hole at least on the inner wall surface of the catalyst.

  The honeycomb structure means a structure having a large number of small holes (cells) penetrating in parallel. The catalyst having such a structure is usually used in a state of being closely fitted in a reaction tube. The cell shape (cross-sectional shape) includes a hexagon, a quadrangle, a triangle, and a circle. Usually, the size (diameter) of a cell is an opening, a wall between cells, and a distance between centers of left and right or upper and lower walls facing each other when attention is paid to one cell is called a pitch.

The catalyst of the present invention preferably has a compressive strength of 50 to 300 N / cm ² when the honeycomb cell has a honeycomb cell thickness (wall thickness) of 1 mm and an opening of 6.4 mm. In such a case, the catalyst of the present invention is preferable because the compressive strength is sufficiently high. If the deposit hole opening area is too large, the compressive strength tends to decrease.
In addition, the measuring method of compressive strength is demonstrated in detail in the Example mentioned later.

The catalyst of the present invention comprises an inorganic oxide support containing Ti, Si and W and at least one metal component selected from the group consisting of V and Mo.
However, in the catalyst of the present invention, components other than the inorganic oxide and the metal component are 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 2% by mass or less. May be included. Moreover, it is preferable that the catalyst of this invention consists of the said inorganic oxide and the said metal component substantially. Here, “substantially” means that impurities and the like that are inevitably contained from the raw material and the production process can be contained, but other than that are not contained.

  Examples of components other than the inorganic oxide and the metal component include Sn, Cu, Fe, Co, Mn, Ce, La, and Y.

  In the catalyst of the present invention, the content of the metal component is preferably 5% by mass or less. The content is preferably 0.1 to 3% by mass, and more preferably 0.3 to 2% by mass.

The catalyst of the present invention has deposit holes which are physical deposition holes for calcium salts. The width of the deposit hole is 4 to 20 μm, and the depth is 20 to 300 μm.
Here, the deposit hole is an opening which is present on the surface of the catalyst which is intentionally formed, and its presence can be confirmed using a scanning electron micrograph (magnification is 100 times).
The method for measuring the width and depth of the deposit hole will be described in detail in the examples described later.

  The width of the deposit hole is preferably 4 to 15 μm, and more preferably 5 to 10 μm.

  The depth of the deposit hole is preferably 50 to 300 μm.

In the catalyst of the present invention, the ratio of the total area of the deposit hole openings to the catalyst inner wall surface area is 5 to 10%. This proportion is preferably 5 to 8%.
The method for measuring the deposit hole opening area will be described in detail in the examples described later.

The catalyst of the present invention preferably has a specific surface area (SA _BET ) measured by the BET method of 50 to 100 m ² / g, and more preferably 60 to 100 m ² / g.

A method for measuring the BET method (BET specific surface area) will be described.
First, a dried sample (0.2 g) is put in a measurement cell, and degassed in a nitrogen gas stream at 300 ° C. for 60 minutes, and then the sample is mixed gas of 30% by volume of nitrogen and 70% by volume of helium. Liquid nitrogen temperature is maintained in a stream of air, and nitrogen is adsorbed to the sample by equilibrium. Next, the temperature of the sample is gradually raised to room temperature while flowing the mixed gas, the amount of nitrogen desorbed during that time is detected, and the specific surface area of the sample is measured using a calibration curve prepared in advance.
Such a BET specific surface area measurement method (nitrogen adsorption method) can be performed using, for example, a conventionally known surface area measurement device.

The catalyst of the present invention preferably has a surface area ratio as measured by mercury intrusion porosimetry method (SA _Hg) is 40 to 80 m ² / g, more preferably 50-80 m ² / g.

  The mercury intrusion porosimetry method is a mercury intrusion method using a porosimeter, and can be measured using, for example, a conventionally known measuring apparatus.

In the catalyst of the present invention, the difference (SA _BET -SA _Hg ) between the specific surface area (SA _BET ) by the BET method and the specific surface area (SA _Hg ) by the mercury intrusion porosimetry method is 15 to 25 m ² / g. This value is preferably 15 to 20 m ² / g.
When SA _BET -SA _Hg is in the above range, it is difficult to deactivate even if it is used when co-firing biomass fuel containing a large amount of calcium.

  Such a catalyst of the present invention can form a deposit hole having a large opening on the surface, so that calcium salt can be accumulated in the deposit hole, or coating of the opening by the calcium salt can be prevented. Deactivation of the catalyst due to precipitation can be suppressed.

Next, the manufacturing method of the catalyst of this invention is demonstrated.
In the catalyst of the present invention, the inorganic oxide support can be produced by mixing inorganic oxides having different shrinkage rates. For example, it can be produced by the method described in JP-A-2004-41893 and JP-A-2005-021780.
The catalyst of the present invention is obtained by obtaining a mixture obtained by mixing the inorganic oxide carrier and the metal component, or these raw materials, and then forming the mixture into a honeycomb structure by an extrusion method or the like. It can be produced by a method of impregnating and supporting a carrier component and an active component on a material.

The catalyst of the present invention includes (1) a step of dehydrating a slurry containing Ti and W and calcining to obtain a Ti—W composite oxide (hereinafter also referred to as “step (1)”), (2) Ti, W and A step of dehydrating a slurry containing Si and firing to obtain a Ti—W—Si composite oxide (hereinafter also referred to as “step (2)”); and (3) a Ti—W composite oxide obtained in the previous step. And Ti—W—Si composite oxide, the ratio of the mass of Ti—W composite oxide to the total mass of these (mass of Ti—W composite oxide / (mass of Ti—W composite oxide + Ti—W— The process of adding, mixing, extruding into a honeycomb shape, drying, and firing (hereinafter referred to as “process”) so that water is added so that the mass of Si composite oxide) × 100 (%)) is 5 to 80 mass%. (3) ") is preferred to be produced by a production method having There.
Hereinafter, such a preferable production method is also referred to as “the production method of the present invention”.

<Production method of the present invention>
Step (1) will be described.
In step (1), first, a slurry containing Ti and W is obtained.
This slurry can be obtained, for example, by dissolving a compound containing Ti and a compound containing W in a solvent such as water, and then adjusting the pH using an acid or alkali to precipitate oxides of Ti and W. . After the precipitation, it is preferably aged at 30 to 98 ° C. for 0.5 to 12 hours.

Here, as the compound containing Ti, metatitanic acid is preferable, and it is preferable to use a titanium sulfate solution obtained from a production process of titanium dioxide according to the sulfuric acid report and further hydrolyze the titanium sulfate to obtain metatitanic acid.
Examples of the compound containing W include tungsten-containing nitrogen compounds such as ammonium paratungstate, ammonium metatungstate, ammonium phosphotungstate, and ammonium tetrathiotungstate, tungsten-containing sulfur compounds such as tungsten disulfide and tungsten trisulfide, and hexachloride. Examples thereof include tungsten, tungsten dichloride, tungsten trichloride, tungsten tetrachloride, tungsten pentachloride, tungsten dichloride dioxide, and tungsten tetrachloride oxide.

The amount ratio of the compound containing Ti and the compound containing W is not particularly limited, but WO ₃ (all of W is equivalent to 100 parts by mass of TiO ₂ (converted value assuming that all of Ti is TiO ₂ )). There converted value assuming that the WO ₃₎ that is preferably adjusted to be 1 to 15 parts by weight.

After obtaining a slurry containing Ti and W as described above, this is dehydrated and fired.
The dehydration method is not particularly limited, and for example, a conventionally known method, specifically, a centrifugal separation method or the like can be applied for dehydration.
The firing method is not particularly limited, and for example, it can be fired using a conventionally known method, specifically, a firing furnace or the like. The firing temperature is, for example, 300 to 700 ° C.
The cake obtained after dehydration may be dried before baking. For drying, for example, a conventionally known method, specifically, an electric dryer or the like can be used. A drying temperature shall be 30-200 degreeC, for example.

  By such a step (1), a Ti—W composite oxide can be obtained.

Step (2) will be described.
In step (2), first, a slurry containing Ti, W and Si is obtained.
This slurry is prepared by, for example, dissolving or dispersing a compound containing Ti, a compound containing W, and a compound containing Si in a solvent such as water, and then adjusting the pH using an acid or alkali to obtain oxides of Ti and W. It can be obtained by precipitation. After the precipitation, it is preferably aged at 30 to 98 ° C. for 0.5 to 12 hours.

Here, as the compound containing Ti and the compound containing W, the same compounds as those in the step (1) can be used.
Examples of the compound containing Si include silica sol, silicic acid solution, fumed silica, and silicon alkoxide.

Further, the amount ratio of the compound containing Ti, the compound containing W and the compound containing Si is not particularly limited, but WO _{3 with} respect to 100 parts by mass of TiO ₂ (converted value assuming that all of Ti is TiO ₂ ). It is preferable to adjust so that (the converted value assuming that all of W is WO ₃ ) is 1 to 10 parts by mass. Further, SiO ₂ (converted value all is assumed to be SiO ₂ of Si) is 1 to 10 parts by weight with respect to TiO ₂ (converted value all is assumed to be of TiO ₂ Ti) 100 parts by weight It is preferable to adjust so that.

After obtaining a slurry containing Ti, W and Si as described above, this is dehydrated and fired.
The dehydration method and the baking method are not particularly limited, and may be the same as in the case of step (1). Moreover, you may perform a drying process similarly to the case of a process (1).

  By such step (2), a Ti—W—Si composite oxide can be obtained.

Step (3) will be described.
In the step (3), the Ti—W composite oxide obtained in the step (1) and the Ti—W—Si composite oxide obtained in the step (2) are combined into the Ti—W composite with respect to the total mass thereof. The ratio of the mass of oxide (mass of Ti—W composite oxide / (mass of Ti—W composite oxide + mass of Ti—W—Si composite oxide) × 100 (%)) is 5 to 80 mass%. Then, add water and mix.
This ratio is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass.

  Ti-W composite oxide and Ti-W-Si composite oxide have different shrinkage ratios due to drying and firing, and when these are mixed and used at a specific mass ratio, the preferred form of deposit holes is formed. The inventor has found that this is easy.

  The Ti—W composite oxide and the Ti—W—Si composite oxide are mixed at a specific mass ratio as described above after adding moisture. Here, if necessary, a molding aid may be further added and mixed. As the molding aid, for example, conventionally known ones can be used, and specific examples include polyethylene oxide, crystalline cellulose, glycerin, polyvinyl alcohol and the like.

Then, the obtained mixture is formed into a honeycomb shape using, for example, a conventionally known forming machine, and then dried and fired.
The drying method is not particularly limited, and for example, a conventionally known method, specifically, an electric dryer or the like can be applied for drying. A drying temperature shall be 30-200 degreeC, for example.
The firing method is not particularly limited, and for example, it can be fired using a conventionally known method, specifically, a firing furnace or the like. The firing temperature is, for example, 450 to 700 ° C.

  By such a production method of the present invention, the catalyst of the present invention can be obtained.

<Exhaust gas treatment method of the present invention>
When coal-fired exhaust gas generated by burning coal-containing fuel containing biomass fuel is brought into contact with the catalyst of the present invention, catalyst deterioration due to clogging of Ca salt-derived pores contained in dust in the exhaust gas is suppressed. Therefore, nitrogen oxides that are causative substances such as photochemical smog and acid rain can be removed more efficiently than conventional catalysts.

  Here, the co-firing rate of biomass fuel with respect to coal in the coal-containing fuel is preferably more than 0% and 50% or less, more preferably more than 0% and 30% or less on a calorie basis.

  For example, when trees such as wood chips and construction waste are used as biomass fuel, the combustion dust of these biomass fuels contains about 5 to 90% of Ca salt in terms of CaO.

  Such biomass fuel is co-fired with coal at the aforementioned ratio, and the exhaust gas is introduced into the step of contacting the catalyst of the present invention. At this time, sulfur oxides discharged by coal combustion react with Ca salt in the combustion dust of biomass fuel, often resulting in an environment where calcium sulfate is likely to be deposited on the catalyst, and the catalyst is resistant to Ca salt poisoning. Is important.

The contact temperature between the coal co-fired exhaust gas and the catalyst of the present invention is usually 250 to 500 ° C, preferably 300 to 400 ° C. The pressure of the catalyst layer is usually −0.05 to 0.9 MPa, preferably −0.01 to 0.5 MPa as a gauge pressure. Also, the space velocity (SV) is usually 100～50000Hr ^-1, preferably 1000~20000Hr ^-1.

  Hereinafter, the present invention will be described based on examples. The present invention is not limited to these examples.

[Raw material preparation (Ti-W composite oxide raw material)]
A metatitanic acid slurry (Ishihara Sangyo) was charged into a stirrer equipped with a reflux condenser, and ammonium paratungstate (manufactured by Shinsei Kagaku Kogyo Co., Ltd.) was added so that WO ₃ was 7 parts by mass with respect to 100 parts by mass of TiO _2. Further, 15% by weight aqueous ammonia was added so as to have a pH of 9.5, followed by heat aging with sufficient stirring at 60 ° C. for 1 hour.
And the obtained slurry was dehydrated and washed, and the dehydrated cake was dried at 110 ° C. and then fired at 500 ° C. to obtain a Ti—W composite oxide raw material.

[Raw material preparation (Ti-W-Si composite oxide raw material)]
A metatitanic acid slurry (Ishihara Sangyo) was charged into a stirrer equipped with a reflux condenser, and ammonium paratungstate (manufactured by Nippon Shin Metal Co., Ltd.) was added thereto so that WO ₃ was 5 parts by mass with respect to 100 parts by mass of TiO _2. Furthermore, silica sol (manufactured by JGC Catalysts & Chemicals, S-20L) was added so that SiO ₂ was 5 parts by mass with respect to 100 parts by mass of TiO ₂ , and 15 wt% aqueous ammonia was added at pH 9.5. Then, the mixture was aged by heating with sufficient stirring at 60 ° C. for 1 hour.
And the obtained slurry was dehydrated and washed, and the dehydrated cake was dried at 110 ° C. and baked at 500 ° C. to obtain a Ti—W—Si composite oxide raw material.

Catalyst preparation [Example 1] Ti-W-Si: 45%
To 13.4 kg of the Ti—W composite oxide raw material and 11.0 kg of the Ti—W—Si composite oxide raw material obtained as described above, 200 g of ammonium metavanadate (manufactured by Shinsei Chemical Industry Co., Ltd.), 15 wt% ammonia water; Add 30 kg, water, 188 g of polyethylene glycol (PEG-20000 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 164 g of crystalline cellulose (Biopoly manufactured by Takeda Pharmaceutical Co., Ltd.). And dried and calcined at 600 ° C. to obtain a catalyst.

[Example 2] Ti-W-Si: 60%
A catalyst was obtained in the same manner as in Example 1 except that 9.76 kg of the Ti—W composite oxide raw material and 14.6 kg of the Ti—W—Si composite oxide raw material were used.

[Example 3] Ti-W-Si: 75%
A catalyst was obtained in the same manner as in Example 1 except that 6.10 kg of the Ti—W composite oxide raw material and 18.3 kg of the Ti—W—Si composite oxide raw material were used.

[Comparative Example 1] Ti-W: 100%
A catalyst was obtained in the same manner as in Example 1 except that 24.4 kg of the Ti—W composite oxide raw material was used and no Ti—W—Si composite oxide raw material was used.

[Comparative Example 2] Ti-W-Si: 15%
A catalyst was obtained in the same manner as in Example 1 except that 20.7 kg of the Ti—W composite oxide raw material and 3.66 kg of the Ti—W—Si composite oxide raw material were used.

[Comparative Example 3] Ti-W-Si: 100%
A catalyst was obtained in the same manner as in Example 1 except that 24.4 kg of the Ti—W—Si composite oxide raw material was used without using the Ti—W composite oxide raw material.

[Test Example 1] Calculation of deposit hole area ratio The catalyst surfaces of the catalysts obtained in Examples and Comparative Examples were observed with an electron microscope.
The measurement apparatus and measurement conditions are shown below.
Measuring device: JEOL JSM-6010LA
Measurement conditions: acceleration voltage 20 kV, low vacuum 30 Pa, magnification 100 times, no evaporation

The observation result of the surface of the catalyst obtained in Example 2 is shown in FIG. 1, and the observation result of the surface of the catalyst obtained in Comparative Example 2 is shown in FIG.
It can be seen that the catalyst obtained in Example 2 is larger in both the width and length of the deposit holes and the number thereof than the catalyst obtained in Comparative Example 2.

A catalyst surface SEM image was taken with the above-mentioned apparatus and conditions, and the image was output so as to have a size of 200 mm long × 286 mm wide. The actual shooting range at this time was 889 μm long × 1,271 μm wide, and the shooting area was 11.3 × 10 ⁵ μm ² .

Next, the maximum width of all the deposit holes observed in the photographed image was measured using a digital caliper. For convenience, the deposit holes intersecting at an angle of 45 degrees or more are counted as separate deposit holes.
Next, the actual maximum deposit hole width was converted from the ratio between the measured maximum deposit hole width and the SEM image scale.

Next, the length of the straight line passing through the center of the deposit hole opening was measured using a digital caliper for the deposit hole having an actual maximum width of 4 μm to 20 μm to obtain the deposit hole length. As shown in FIG. 3, when the deposit hole is wavy, a straight line passing through the center in the width direction of the deposit hole opening is appropriately redrawn according to the waviness, and the total of the straight lengths is defined as the deposit hole length.
Next, the actual deposit hole length was converted from the ratio of the measured deposit hole length to the SEM image scale.
Next, in all the deposit holes having a maximum width of 4 μm to 20 μm, the converted actual deposit hole maximum width × actual deposit hole length was calculated, and the sum of the values was defined as the deposit hole area.
The value of the deposit hole area / photographing area was defined as the ratio of the sum of the deposit hole opening area to the catalyst inner wall surface area.

Table 1 shows the ratio of the total area of the deposit hole openings in the catalysts of Examples 1 to 3 and Comparative Examples 1 to 3 to the catalyst inner wall surface area (denoted as the deposit hole area ratio in Table 1).
In the case of the catalyst of Examples 1-3, it became in the range of 5-10. On the other hand, in the case of the catalysts of Comparative Examples 1 to 3, the value was out of this range.

Test Example 2 Measurement of Deposit Hole Depth As shown in FIG. 4, first, the inner part of each catalyst obtained in Examples and Comparative Examples was cut out to about 5 mm × 5 mm and embedded in an epoxy resin. And used as a sample. And the obtained sample was rough-cut so that an inner-surface cross section might come out, and it surfaced.
Next, the measurement surface was cut out smoothly using an ion milling device. The ion milling apparatus and processing conditions are as follows.
Ion milling equipment: Hitachi E-3500
Processing conditions: discharge voltage 4 kV, argon ion acceleration voltage 6 kV, discharge current 350 to 500 μA, ion current 60 to 150 μA

Next, SEM measurement was performed on the inner cross-section of the catalyst that was ion milled. Measuring devices and measuring conditions are as follows.
Measuring device: JEOL JSM-7600F
Measurement conditions: acceleration voltage 20 kV, high vacuum, carbon deposition

Next, of the deposit holes confirmed in the cross section measured by SEM, the width of the surface opening is measured with a digital caliper, and the actual deposit hole width converted from the ratio of the SEM image scale is 4 μm or more. About the hole, the depth from the surface opening was measured with a digital caliper as shown in FIG.
And the value which converted the measured depth from the ratio of the scale of a SEM image was made into the actual deposit hole depth.

  In the case of the catalysts of Examples 1 to 3, the depth of the deposit holes was in the range of 20 to 300 μm.

[Test Example 3] Estimation of specific surface area derived from deposit holes by BET specific surface area measurement and mercury porosimeter specific surface area measurement For each of the catalysts obtained in Examples and Comparative Examples, a BET specific surface area measurement value and 5 nm to 5 μm by a mercury porosimeter The specific surface area measurement values occupied by the pores were compared. Specific surface area SA _BET by the BET method is a value of the specific surface area formed by all the pores and deposits of large and small, and from this value, the measured value of the specific surface area SA _Hg occupied by the pores of 5 nm to 5 μm by the mercury porosimeter The subtracted value is a value that correlates with the specific surface area value derived from the deposit holes, and serves as an index indicating that the deposit holes are uniformly distributed on the catalyst surface.
The BET specific surface area measurement and the mercury porosimeter specific surface area measurement were performed under the following conditions.
BET specific surface area measuring device: Mountaintech HM model-1220
BET specific surface area measurement conditions: pretreatment at 300 ° C. for 1 hour, BET single point method Mercury porosimeter specific surface area measuring device: Quantachrome PoreMaster
Mercury porosimeter specific surface area measurement conditions: pretreatment 300 ° C. for 1 hour, mercury intrusion angle 130 °, surface tension 473 erg / cm ²

Table 1 shows the measured BET specific surface area (SA _BET ) and the measured specific surface area (SA _Hg ) occupied by pores of 5 nm to 5 μm in the measurement of the mercury porosimeter specific surface area. The value of SA _BET -SA _Hg was in the range of 15-25 for the catalysts of Examples 1-3. On the other hand, in the case of the catalysts of Comparative Examples 1 to 3, the value was out of this range. Moreover, it can be said that the deposit holes in the catalysts of Examples 1 to 3 are uniformly distributed, not only a part of the catalyst surface.

[Test Example 4] Accelerated deterioration test of catalyst by CaCl ₂ solution spray For each of the catalysts obtained in Examples and Comparative Examples, the catalyst was cut into 2 × 2 × 107 mmL (thickness 1 mm, opening 6.4 mm), quartz After setting in the reaction tube, the catalyst denitration performance in the Fresh state was measured. The denitration rate obtained here was defined as η ₀ (%).
Thereafter, a nozzle for spraying the CaCl ₂ solution was attached to the quartz reaction tube, and the CaCl ₂ solution was added from the upstream side of the catalyst. The nozzle was installed 300 mm away from the upstream end face of the quartz reaction tube. The concentration of the CaCl ₂ solution was 0.5% by mass, and the spraying time was 24 hours. After spraying the CaCl ₂ solution, the denitration performance of the catalyst was measured again. The denitration rate obtained here was defined as η (%). Then, η / η ₀ was obtained and compared with the performance in the Fresh state. Both performance measurement and CaCl ₂ solution spraying were performed at 320 ° C. The measurement conditions are as shown below.
At the time of activity measurement SV = 19290 (1 / h), f = 0.54 (Nm ³ / h), AV = 47.94 (Nm ³ / m ² h), NO = 180 (volume ppm), NH ₃ = 180 (Ppm by volume), SO ₂ = 500 (ppm by volume), O ₂ = 7% by volume, H ₂ O = 10% by volume, N ₂ = balance at the time of CaCl ₂ solution spraying SV = 19290 (1 / h), f = 0 ^{.54 (Nm 3 /h),AV=47.94(Nm 3 / m} 2 h), NO = 0 ( volume ppm), NH ₃ = 0 (volume ppm), SO ₂ = 1000 (volume ppm), O ₂ = 7% by volume, H ₂ O = 10% by volume (as CaCl ₂ solution), N ₂ = balance

The results are shown in Table 1. Compared with the catalysts of Comparative Examples 1 to 3, it can be seen that the catalysts of Examples 1 to 3 have high activity even after CaCl ₂ solution spraying, and the deterioration due to calcium is suppressed.

[Test Example 5] Surface observation by electron microscope of catalyst after CaCl ₂ solution spray test Confirms whether the pores are large and the amount of deposit pores prevents physical pore blockage and surface coating by calcium. In order to do this, the catalyst inner wall 10 mm from the upstream end face of the catalyst of Example 2 and the catalyst of Comparative Example 2 after the 0.5% CaCl ₂ solution sprayed in Test Example 4 for 24 hours was sampled, and the surface state was determined. Observed with an electron microscope. The measurement conditions are as follows.
Measuring device: JSM-6010LA, manufactured by JEOL Ltd.
Measurement conditions: acceleration voltage 20 kV, low vacuum 30 Pa, magnification 190-200 times, no evaporation

The 0.5% CaCl ₂ The results of the solution 24h of the catalyst of Example 2 after spraying in Figure 6,0.5% CaCl ₂ solution 24h later comparison spraying Example 2 catalyst results shown in Figure 7.
In the catalyst of Comparative Example 2, a large amount of calcium sulfate was deposited on the surface after the deterioration test, and the surface was coated. On the other hand, in the catalyst of Example 2, calcium sulfate slightly starts to precipitate in some places, but the catalyst surface and deposit holes are not covered. From this, it can be said that the catalyst of Example 2 having large deposit holes and a large amount of cracks has high deterioration resistance against physical coating of calcium.

[Test Example 6] Measurement of compressive strength In each of Examples 1 to 3 and Comparative Examples 1 to 3, extrusion was performed in a honeycomb shape so that the wall thickness was 1 mm and the opening was 6.4 mm, and after drying, 600 The catalyst was obtained by calcining at 0 ° C. Then, after the catalyst was cut into a cubic shape, as shown in FIG. 8, the catalyst was compressed in a direction perpendicular to the catalyst through hole, and the pressure when the catalyst was completely destroyed was measured.
The results are shown in Table 1. In the case of the catalysts of Examples 1 to 3, the compressive strength was in the range of 50 to 300 N / cm ² . That is, it was confirmed that the honeycomb catalyst had a high compressive strength.

Claims (4)

A honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas, comprising an inorganic oxide support containing Ti, Si and W, and a metal component containing at least one selected from V and Mo,
It has a deposit hole with a width of 4 to 20 μm and a depth of 20 to 300 μm, which is a physical deposition hole for calcium salt, and the ratio of the total area of the deposit hole openings to the surface area of the inner wall of the catalyst is 5 to 10%. And
The difference (SA _BET -SA _Hg ) between the specific surface area (SA _BET ) by the BET method and the specific surface area (SA _Hg ) exhibited by the catalyst pores of 5 nm to 5 μm by the mercury intrusion porosimetry method is 15 to 25 m ² / g A honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas, characterized by being in the range. Coal and biomass co-combustion exhaust gas treatment according to claim 1 in which the compressive strength in the case where the thickness of the honeycomb cells 1 mm, a honeycomb catalyst and 6.4mm the mesh is characterized in that it is a 50~300N / cm ² Honeycomb catalyst. (1) dehydrating a slurry containing Ti and W and firing to obtain a Ti-W composite oxide;
(2) dehydrating a slurry containing Ti, W and Si and firing to obtain a Ti—W—Si composite oxide;
(3) The ratio of the mass of the Ti—W composite oxide to the total mass of the Ti—W composite oxide and Ti—W—Si composite oxide obtained in the previous step (of the Ti—W composite oxide). The mixture was added after adding water so that the mass / (mass of Ti—W composite oxide + mass of Ti—W—Si composite oxide) × 100 (%)) was 5 to 80% by mass. A process of extruding, molding, drying and firing,
The method for producing a honeycomb catalyst for treating coal and biomass mixed combustion exhaust gas according to claim 1 or 2, characterized in that   The coal according to claim 1 or 2 is brought into contact with the coal-fired exhaust gas treatment honeycomb catalyst, which is mixed with coal-fired exhaust gas containing biomass fuel of more than 0% and not more than 50% on a calorie basis. And biomass mixed combustion exhaust gas treatment method.