JP2016016339A - Honeycomb type denitration catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemically resistant denitration catalyst that prevents deterioration of the strength of a denitration catalyst in chemical washing for catalyst regeneration, and can be regenerated and used repeatedly through catalyst regeneration treatment.SOLUTION: A honeycomb type denitration catalyst according to the present invention is obtained by adding, to denitration catalyst powder with at least TiOpresent therein, a glass fiber as another component, the glass fiber comprising SiOas the essential component and also comprising an oxide of at least one element selected from the group consisting of ZrO, and Ti, Mg, Na and K.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a honeycomb type denitration catalyst, and more particularly to a honeycomb type denitration catalyst used in a flue gas denitration apparatus.

  Conventionally, a denitration catalyst used in a power plant such as a thermal power plant is a poisonous substance caused by dust, dust, arsenic (As), vanadium (V), etc. in exhaust gas by burning fuel with the usage time. Adheres to the surface and its catalytic ability decreases. The catalyst whose denitrification ability has been reduced is subjected to a cleaning regeneration process using a chemical solution in order to be reused in a denitration apparatus (hereinafter also referred to as an actual machine) at a power plant. However, when the honeycomb catalyst is washed with a chemical solution, the honeycomb strength is lowered, and therefore a denitration catalyst suitable for the regeneration treatment is demanded.

  As such a denitration catalyst, a honeycomb type denitration catalyst to which an inexpensive glass fiber is added as an aggregate is known.

  Such a denitration catalyst was immersed in an alkaline aqueous solution and / or an acidic aqueous solution as a regeneration treatment (hereinafter also referred to as a chemical washing regeneration treatment) after being used until the performance of the denitration catalyst decreased.

As a result, aluminum oxide (Al ₂ O ₃ ), diboron trioxide (B ₂ O ₃ ), and the like contained in the glass fiber are eluted into the chemical solution, and the strength of the denitration catalyst that has been subjected to the chemical washing regeneration treatment is reduced. Has been experienced. Therefore, in general, the chemical cleaning regeneration treatment of the denitration catalyst is limited to one time, and in many cases, the regeneration reuse of the denitration catalyst that has been subjected to the chemical regeneration processing is mostly limited to one time. .

Patent No. 4394343

  In light of the above circumstances, an object of the present invention is to provide a honeycomb type denitration catalyst that suppresses a decrease in strength of a denitration catalyst during a chemical washing regeneration process for catalyst regeneration and can be repeatedly regenerated by the chemical washing regeneration process. And

In order to achieve the above object, the honeycomb type denitration catalyst according to the present invention includes a denitration catalyst powder containing at least TiO ₂ , SiO ₂ as an essential component, ZrO ₂ , and a group consisting of Ti, Mg, Na and K. A glass fiber containing an oxide of one or more selected elements is added as another component. That is, the glass fiber contains SiO ₂ , ZrO _2, and an oxide of one or more elements selected from the group consisting of Ti, Mg, Na, and K.

Further, the content of B ₂ O ₃ of the glass fibers is preferably not more than 5 wt% 0 wt% or more. Furthermore, it is preferable that the glass fiber does not contain CaO.

With such a composition, even if the used honeycomb type denitration catalyst is immersed in an aqueous NaOH solution having a concentration of 1 N for about 24 hours as a chemical washing reuse treatment, it is possible to prevent the glass fiber component as a skeleton from eluting. it can. Further, as a chemical washing reuse treatment, in addition to the treatment with the NaOH aqueous solution, even if the used honeycomb type denitration catalyst is immersed in a 1N concentration H ₂ SO ₄ aqueous solution for about 24 hours, the elution of the glass fiber component is prevented. be able to.

  Moreover, it is preferable that the addition amount of the glass fiber is in the range of 1 part by weight or more and 10 parts by weight or less based on 100 parts by weight of the denitration catalyst powder.

  Within such a numerical range, it is possible to prevent a possibility that the predetermined initial performance cannot be exhibited due to a decrease in the catalyst component, and it is possible to prevent a possibility that the durability of the catalyst is lowered.

In addition, the content of ZrO _{2 in} the glass fiber is preferably 16% by weight or more and 24% by weight or less. Furthermore, the content of SiO _{2 in} the glass fiber is 54 wt% or more and 65 wt% or less, the content of TiO ₂ is 0 wt% or more and 10 wt% or less, and the content of MgO is 0 wt% or more. It is preferably 10% by weight or less, the content of Na ₂ O is 10% by weight or more and 30% by weight or less, and the content of K ₂ O is preferably 10% by weight or more and 30% by weight or less.

In such a numerical range, as a chemical washing reuse treatment, the used honeycomb type denitration catalyst is immersed in a 1N concentration NaOH aqueous solution for about 24 hours and then immersed in a 1N concentration H ₂ SO ₄ aqueous solution for about 24 hours. Moreover, it can avoid that a glass fiber component elutes.

The denitration catalyst powder is preferably formed by supporting TiO ₂ as a carrier and V ₂ O ₅ and / or WO ₃ as active components.

With such a composition, V and / or W on TiO ₂ function as an active point of the catalyst, and NO _X such as NO and NO ₂ can be efficiently denitrated in the presence of oxygen. That is, a denitrification function such as high activity and selectivity can be imparted to the denitration catalyst.

  In light of the above object, according to the present invention, it is possible to provide a honeycomb type denitration catalyst that can suppress a decrease in strength of the denitration catalyst during the chemical cleaning regeneration process for catalyst regeneration and can be repeatedly regenerated by the chemical cleaning regeneration process.

FIG. 1 is a schematic view showing an embodiment of a honeycomb type denitration catalyst according to the present invention. FIG. 2 is a schematic flow diagram showing an embodiment of regenerating the honeycomb type denitration catalyst according to the present invention. FIG. 3 is a graph showing the results of the compressive strength test of the example for the honeycomb type denitration catalyst according to the present invention. FIG. 4 is a graph showing the results of the alkali resistance test of the examples for the honeycomb type denitration catalyst according to the present invention. FIG. 5 is a graph showing components eluted in the alkali resistance test of the examples of the honeycomb type denitration catalyst according to the present invention. FIG. 6 is a graph showing the results of an acid resistance test of an example for the honeycomb type denitration catalyst according to the present invention. FIG. 7 is a graph showing components eluted in the acid resistance test of the examples of the honeycomb type denitration catalyst according to the present invention. FIG. 8 is a graph showing the result of the trial calculation of the compressive strength after the chemical washing of the example for the honeycomb type denitration catalyst according to the present invention. FIG. 9 is a graph showing a trial calculation result of the wear rate after completion of the chemical cleaning of the example for the honeycomb type denitration catalyst according to the present invention.

  Hereinafter, an embodiment of a honeycomb type denitration catalyst according to the present invention will be described in detail. FIG. 1 is a schematic view showing an embodiment of a honeycomb type denitration catalyst according to the present invention. As shown in FIG. 1, the honeycomb type denitration catalyst 1 has a honeycomb structure having a large number of pores 1a, and includes a denitration catalyst powder and glass fibers at least as constituent elements.

  The honeycomb type denitration catalyst 1 is formed by adding the glass fiber as a binder to the denitration catalyst powder and kneading together. The forming method of the honeycomb type denitration catalyst 1 is not particularly limited as long as it is a forming method capable of functioning as a denitration catalyst having a honeycomb structure. As an example, the honeycomb type denitration catalyst 1 is formed by kneading the denitration catalyst powder with another compound such as the binder and water in a known kneader, and then molding the honeycomb structure with a known extruder. Can be molded. The honeycomb structure may be a honeycomb structure having a cross section such as a circle, an ellipse, a triangle, a pentagon, and a hexagon. In addition, to the honeycomb type denitration catalyst 1, powder obtained by pulverizing a used denitration catalyst with an actual machine can be added.

The denitration catalyst powder is a powdered metal oxide containing at least titanium dioxide (TiO ₂ ). The composition of the denitration catalyst powder is not particularly limited as long as it contains at least titanium dioxide (TiO ₂ ). More specifically, the denitration catalyst powder is a powder obtained by supporting TiO ₂ as a carrier and supporting vanadium pentoxide (V ₂ O ₅ ) and / or tungsten trioxide (WO ₃ ) as an active ingredient. preferable. In this case, nitrogen oxides (NO _x ) such as NO and NO ₂ in the denitration object can be efficiently denitrated in the presence of oxygen.

  The denitration catalyst powder carrier may include an oxide containing at least one element selected from the group consisting of titanium (Ti), silicon (Si), zirconium (Zr), and cerium (Ce). The composite oxide containing at least two or more elements selected from the group may be included. Moreover, the said active component should just function as an active point on a denitration catalyst, and is not specifically limited. More specifically, the active component is vanadium (V), tungsten (W), molybdenum (Mo), iron (Fe), cobalt (Co), platinum (Pt), nickel (Ni), ruthenium (Ru). , Iridium (Ir), rhodium (Rh) or a mixture thereof. Of these, the active ingredient is preferably vanadium (V) and / or tungsten (W).

  The glass fiber has a predetermined diameter and length, and is contained in the denitration catalyst powder in a predetermined amount. Further, the glass fiber functions as a binder in the denitration catalyst, and is configured to improve the strength of the denitration catalyst by adding a matrix structure to the denitration catalyst.

The glass fiber has silicon dioxide (SiO ₂ ) as an essential component, and other components are selected from the group consisting of zirconia (ZrO ₂ ) and titanium (Ti), magnesium (Mg), sodium (Na), and potassium (K). An oxide of one or more elements. Examples of the other components include titanium dioxide (TiO ₂ ), magnesium oxide (MgO), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), lithium oxide (Li ₂ O), and mixtures thereof. . The oxide preferably does not substantially contain diboron trioxide (B ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ), and more preferably does not substantially contain calcium oxide (CaO). .

  For these reasons, it is preferable to use the glass fiber from which the first chemical washing step and the second chemical washing step, which will be described later, are performed in advance and the components dissolved in the alkali cleaning solution and the acid cleaning solution are removed. is there. In this case, the elution of the glass fiber component that becomes the skeleton of the honeycomb type denitration catalyst 1 can be suitably prevented.

The content (addition amount) of SiO ₂ which is an essential component in the glass fiber is preferably 54% by weight or more and 65% by weight or less. The content of ZrO ₂ which is another component in the glass fiber is more preferably 16% by weight or more and 24% by weight or less. The content of ZrO ₂ is not an oxide of the glass fiber may be any content that can function as a binder, without limitation. More specifically, as the content of the oxide in the glass fiber, TiO ₂ is preferably 0 wt% or more and 10 wt% or less, and MgO is 0 wt% or more and 10 wt% or less. Preferably, Na ₂ O is preferably 10% by weight to 30% by weight, and K ₂ O is preferably 10% by weight to 30% by weight.

More preferably, B ₂ O ₃ in the glass fiber is not substantially contained. As an example, the content of B ₂ O ₃ can be 0 wt% or more and 5 wt% or less. More preferably, Al ₂ O ₃ is not substantially contained. As an example, the content of Al ₂ O ₃ can be 0 wt% or more and 2 wt% or less. More preferably, CaO is not substantially contained. As an example, the content of CaO can be 0 wt% or more and 10 wt% or less. Within the above range, even when immersed about 24 hours NaOH solution and aqueous H ₂ SO _4, the components of the glass fibers from each oxide can be suitably prevented from eluting.

  The content (addition amount) of the glass fiber to the denitration catalyst powder is 0.1 parts by weight or more and 10 parts by weight with respect to 100 parts by weight of the denitration catalyst powder from the viewpoint of the performance of the denitration catalyst and the moldability of the honeycomb structure. It can be within the range of less than or equal to parts, and is preferably. If the glass fiber content exceeds 10 parts by weight, the catalyst component may be reduced by that amount, which may result in the catalyst not being able to exhibit a predetermined initial performance. .

  The diameter of the glass fiber is not particularly limited as long as it can form a honeycomb structure denitration catalyst. More specifically, the diameter of the glass fiber is preferably in the range of 11 μm or more and 18 μm or less, more preferably in the range of 14 μm or more and 18 μm or less, from the viewpoint of the moldability of the honeycomb structure.

  The length of the glass fiber is not particularly limited as long as it can form a denitration catalyst having a honeycomb structure. More specifically, the length of the glass fiber is preferably in the range of 3 mm to 13 mm, more preferably in the range of 6 mm to 13 mm, from the viewpoint of the formability of the honeycomb structure.

  One embodiment for regenerating a honeycomb type denitration catalyst having the above configuration will be described in more detail with reference to the accompanying drawings.

  FIG. 2 is a schematic flow diagram showing an embodiment of regenerating the honeycomb type denitration catalyst according to the present invention. As shown in FIG. 2, when the honeycomb type denitration catalyst according to the present invention is regenerated, the honeycomb type denitration catalyst 1 is used until the performance of the honeycomb type denitration catalyst 1 decreases in an actual power plant, and then regenerated at the factory. The honeycomb type denitration catalyst which is placed in the actual machine and used again is regenerated. More specifically, the first water washing step (S1), the first chemical washing step (S2) immersed in the alkaline cleaning liquid, the second chemical washing step (S3) immersed in the acid cleaning liquid, and the second At least the water washing step (S4) and the first drying step (S5) are performed. In the present embodiment, “used” means that the step of preparing a used denitration catalyst is a denitration catalyst device that denitrates exhaust gas from a boiler that burns fuel derived from petroleum or coal, and its denitration performance is reduced. It means that it was used until.

  In the first water washing step (S1), the used denitration catalyst is washed with water at a normal temperature (14 ° C. to 18 ° C.) for 30 minutes using a predetermined volume of water. Thereby, used honeycomb type denitration catalyst, in particular, adhering substances such as soot and dust adhering in the pores can be removed.

  The temperature of the water used in the first water washing step (S1) is not particularly limited as long as it is a temperature at which adhered substances such as dust and dust attached to the used denitration catalyst can be sufficiently removed. More specifically, the temperature of water is preferably in the range of 10 ° C. or higher and 80 ° C. or lower. If the water temperature is less than 10 ° C, the heat energy for cooling the water may be wasted, and if the water temperature exceeds 80 ° C, the heat energy for heating the water may be wasted. The processing cost of a 1st water washing process becomes high.

  The washing time required for the first washing step (S1) is not particularly limited as long as it is a temperature at which the adhered substance can be sufficiently removed from the used denitration catalyst. More specifically, the washing time is preferably in the range of 30 minutes to 5 hours. If the washing time is less than 30 minutes, there is a possibility that the adhered substances adhering to the denitration catalyst cannot be removed sufficiently. If the water washing time exceeds 5 hours, the washing time after completely removing the adhered substances is wasted, and the processing cost required for the first water washing step is increased.

  The volume of water used in the first water washing step (S1) is 1: 3 in the volume ratio of denitration catalyst: water. More specifically, the volume of water used in this step is preferably in the range of 1: 1 to 10 and in the range of 1: 2 to 5 as a denitration catalyst: water volume ratio. Is particularly preferred. If the volume ratio of water to the denitration catalyst is less than 1, there is a possibility that the substance attached to the denitration catalyst cannot be removed sufficiently. When the volume ratio of water to the denitration catalyst exceeds 5, the processing cost required for the first water washing process increases.

In the first chemical washing step (S2), the denitration catalyst that has undergone the first water washing step (S1) is changed to 55 ° C. in an alkaline washing solution having a concentration of 1N and a predetermined volume of sodium hydroxide (NaOH) aqueous solution. Immerse at a temperature of 65 ° C. or lower for about 1 hour. Thereby, poisonous substances such as vanadium oxysulfate (VOSO ₄ ) and diarsenic trioxide (As ₂ O ₃ ) deposited on the surface of the used denitration catalyst can be removed.

The alkaline cleaning liquid used in the first chemical cleaning step (S2) is not particularly limited as long as it is an aqueous solution or solution exhibiting alkalinity that can sufficiently remove poisonous substances. As the alkaline cleaning solution, an aqueous solution of potassium hydroxide (KOH), sodium carbonate (Na ₂ CO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ), potassium carbonate (K ₂ CO ₃ ), or the like can be used in addition to the aqueous NaOH solution. it can. Among these, from the viewpoint of practicality and processing cost, it is preferable to use an aqueous NaOH solution as the alkaline cleaning solution.

  The concentration of the alkaline cleaning liquid used in the first chemical cleaning step (S2) may be a concentration that can sufficiently remove poisonous substances attached to the denitration catalyst. More specifically, when an aqueous NaOH solution is used, the concentration of the aqueous NaOH solution is preferably within a range of 0.5N to 2.0N, and preferably within a range of 0.7N to 1.5N. More preferably, it is in the range of 0.8N or more and 1.2N or less. If the concentration of the NaOH aqueous solution is less than 0.5 N, there is a possibility that poisonous substances adhering to the used denitration catalyst cannot be removed sufficiently. If the concentration of the NaOH aqueous solution exceeds 2.0 N, the equipment and material costs required for the first chemical washing process increase. Even when a solution other than NaOH aqueous solution is used as the alkaline cleaning liquid, the concentration of the alkaline cleaning liquid is not particularly limited as long as it is a concentration that can sufficiently remove poisonous substances. As an example, the concentration of the alkaline cleaning liquid can be in the range of 0.05 wt% to 20 wt%. If the concentration of the alkaline cleaning liquid is less than 0.05% by weight, there is a possibility that poisonous substances adhering to the used denitration catalyst cannot be removed sufficiently. If the concentration of the alkaline cleaning liquid exceeds 20% by weight, the equipment and material costs required for the first chemical cleaning process are increased.

  The temperature of the acid cleaning solution used in the first chemical cleaning step (S2) may be a concentration that can sufficiently remove poisonous substances adhering to the denitration catalyst, while depending on the alkaline aqueous solution used. More specifically, when an aqueous NaOH solution is used, the temperature of the aqueous NaOH solution is preferably in the range of 10 ° C. or higher and 90 ° C. or lower, more preferably in the range of 20 ° C. or higher and 75 ° C. or lower. More preferably, it is in the range of not lower than 65 ° C. and lower than 65 ° C. If the temperature of the NaOH aqueous solution is less than 10 ° C., there is a possibility that poisonous substances adhering to the denitration catalyst cannot be sufficiently removed. When the temperature of the NaOH aqueous solution exceeds 90 ° C., the equipment and material costs required for the first chemical washing process increase.

  The washing time required for the first chemical washing step (S2) is not particularly limited as long as it can sufficiently remove the poisonous substance from the denitration catalyst, although it affects conditions such as the composition, concentration, and temperature of the alkaline washing liquid. As an example, the cleaning time with the alkaline cleaning liquid can be about 30 minutes to 120 minutes.

  The volume of the alkaline cleaning liquid used in the first chemical cleaning step (S2) is 1: 3 in a volume ratio of denitration catalyst: NaOH aqueous solution when an aqueous NaOH solution is used as the alkaline cleaning liquid. More specifically, the volume of the NaOH aqueous solution used in this step is preferably in the range of 1: 1 to 10, and in the range of 1: 2 to 5 in the volume ratio of the denitration catalyst: NaOH aqueous solution. It is particularly preferred that If the volume ratio of the NaOH aqueous solution to the denitration catalyst is less than 1, there is a possibility that poisonous substances attached to the used denitration catalyst cannot be sufficiently removed. When the volume ratio of the NaOH aqueous solution to the denitration catalyst exceeds 5, the processing cost required for the first chemical washing process increases.

In the second chemical washing step (S3), the denitration catalyst that has undergone the first chemical washing step (S2) is converted into an acid washing solution having a concentration of 1N and a predetermined volume of sulfuric acid (H ₂ SO ₃ ) aqueous solution. Immerse for about 1 hour at room temperature. Thereby, it is possible to neutralize the alkali component remaining in the denitration catalyst through the first chemical cleaning step and prevent the denitration catalyst from being poisoned by the remaining alkali component.

The acid cleaning solution used in the second chemical washing step (S3) may be an aqueous solution or solution that exhibits acidity to the extent that the alkali component in the denitration catalyst can be neutralized. More specifically, as the acid cleaning solution, an aqueous solution of sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCl), nitric acid (HNO ₃ ), hydrogen fluoride (HF), or the like can be used. Among these, from the viewpoint of practicality, it is preferable to use an H ₂ SO ₄ aqueous solution as the alkaline cleaning liquid.

The concentration of the acid cleaning solution used in the second chemical cleaning step (S3) may be a concentration that can neutralize the alkaline component in the denitration catalyst when an H ₂ SO ₄ aqueous solution is used. More specifically, the concentration of the H ₂ SO ₄ aqueous solution is preferably in the range of 0.5N to 2.0N, more preferably in the range of 0.7N to 1.5N, More preferably, it is within the range of 0.8N or more and 1.2N or less. If the concentration of the H ₂ SO ₄ aqueous solution is less than 0.5 N, ion exchange with ions of alkali components in the denitration catalyst may not be performed sufficiently. If the concentration of the H ₂ SO ₄ aqueous solution exceeds 2.0 N, the equipment and material costs required for the second chemical washing process increase.

The temperature of the acid cleaning solution used in the second chemical cleaning step (S3) may be any temperature that can neutralize the alkali component in the denitration catalyst when an H ₂ SO ₄ aqueous solution is used. More specifically, the temperature of the aqueous H ₂ SO ₄ solution is preferably in the range of 10 ° C. or higher and 90 ° C. or lower, more preferably in the range of 20 ° C. or higher and 75 ° C. or lower, and 25 ° C. or higher and 50 ° C. or lower. It is more preferable that the temperature is within a range of ° C or less. If the temperature of the H ₂ SO ₄ aqueous solution is lower than 10 ° C., there is a possibility that ion exchange with ions of alkali components in the denitration catalyst is not sufficiently performed. When the temperature of the H ₂ SO ₄ aqueous solution exceeds 40 ° C., the equipment and material costs required for the second chemical washing process are increased.

  The washing time with the acid washing solution used in the second chemical washing step (S3) is not particularly limited as long as it can sufficiently neutralize the alkali component, although it affects the conditions such as the composition, concentration, and temperature of the acid washing solution. As an example, the cleaning time with the acid cleaning liquid can be about 30 minutes to 120 minutes.

The volume of the acid cleaning liquid used in the second chemical cleaning step (S3) is 1: 3 in a volume ratio of denitration catalyst: H ₂ SO ₄ aqueous solution when an H ₂ SO ₄ aqueous solution is used as the acid cleaning liquid. More specifically, the volume of the H ₂ SO ₄ aqueous solution used in this step is preferably in the range of 1: 1 to 10 in terms of the volume ratio of the denitration catalyst: H ₂ SO ₄ aqueous solution, A range of 2 to 5 is particularly preferable. When the volume ratio of the H ₂ SO ₄ aqueous solution to the denitration catalyst is less than 1, ion exchange with ions of the alkali component in the denitration catalyst may not be sufficiently performed, and the alkali component cannot be sufficiently neutralized. If the volume ratio of the H ₂ SO ₄ aqueous solution to the denitration catalyst exceeds 5, the processing cost required for the _second chemical washing process increases.

  In the second water washing step (S4), the denitration catalyst after the second chemical washing step (S3) is washed with a predetermined volume of water at room temperature for 30 minutes. Thereby, the acid remaining in the denitration catalyst can be completely removed.

  The temperature of the water used in the second water washing step (S4) is not particularly limited as long as it is a temperature that can sufficiently remove the adhered substances. More specifically, the temperature of water is preferably in the range of 10 ° C. or higher and 80 ° C. or lower. If the temperature of the water is less than 10 ° C., the acid remaining in the denitration catalyst may be sufficiently dissolved in water and cannot be removed. If the temperature of the water exceeds 80 ° C., the heat energy for heating the water may be wasted, and the processing cost of the second water washing step will increase.

  The washing time used in the second washing step (S4) is not particularly limited as long as it is a temperature at which the adhered substances can be sufficiently removed. More specifically, the washing time is preferably in the range of 30 minutes to 5 hours. If the washing time is less than 30 minutes, the acid remaining in the denitration catalyst may not be sufficiently removed. When the water washing time exceeds 5 hours, the washing time after completely removing the adhered substances is wasted, and the processing cost of the second water washing step is increased.

  The volume of water used in the second water washing step (S4) is 1: 3 in the volume ratio of denitration catalyst: water. More specifically, the denitration catalyst: water volume ratio is preferably in the range of 1: 1 to 10 and particularly preferably in the range of 1: 2 to 5. If the volume ratio of water to the denitration catalyst is less than 1, there is a possibility that the substance attached to the denitration catalyst cannot be removed sufficiently. When the volume ratio of water to the denitration catalyst exceeds 5, the processing cost required for the second water washing process increases.

  In the first drying step (S5), the denitration catalyst after the second water washing step (S4) is dried at 105 ° C. for at least 4 hours. The drying temperature and drying time are not particularly limited as long as the drying temperature and drying time can sufficiently dry the denitration catalyst. More specifically, the drying temperature is preferably in the range of 90 ° C. or higher and 150 ° C. or lower. If the drying temperature is less than 90 ° C., the denitration catalyst may not be sufficiently dried. If the drying temperature exceeds 150 ° C., the processing equipment cost required for the first drying step increases. The drying time is preferably in the range of 1 hour to 10 hours. If the drying time is less than 1 hour, the denitration catalyst may not be sufficiently dried. If the drying time exceeds 10 hours, the cost of the processing equipment required for the first drying step increases. After the first drying step (S5), the regenerated honeycomb type denitration catalyst can be inserted into the denitration apparatus and used again.

  Further, in regenerating the honeycomb type denitration catalyst according to the present invention, after the first drying step (S5), the active component immersion step (first immersion step: S6), the second drying step (S7), , Can be implemented.

In the first impregnation step (S6), the denitration catalyst after the first drying step (S5) is immersed in an aqueous solution in which a vanadium compound such as vanadyl sulfate (VOSO ₄ ) is dissolved in water. While the VOSO ₄ volumed on the catalyst surface is removed by the first chemical washing treatment, V supported as an active component of the denitration catalyst is eluted, and the concentration of the active component may be reduced in the denitration catalyst. is there. Due to such a decrease in the active ingredient concentration, the denitration ability may decrease. In this step, the active component is impregnated on the carrier and supported so that the concentration of the active component such as V in the denitration catalyst is equal to or substantially equal to that before the regeneration treatment.

In the first impregnation step (S6), in addition to vanadyl sulfate (VOSO ₄ ), vanadium compounds such as vanadium pentoxide (V ₂ O ₅ ) and ammonium metavanadate (NH ₄ VO ₃ ) can be used. In addition, as a solution for dissolving the vanadyl compound, an organic acid, an amine solution, or the like can be used instead of water.

  The amount of the vanadium compound aqueous solution used in the first impregnation step (S6) is preferably in the range of 1:10 or more and 1: 1 or less by volume ratio with respect to the denitration catalyst. The temperature of the vanadium compound aqueous solution is preferably in the range of 0 ° C. or higher and 40 ° C. or lower. Moreover, the immersion time of the denitration catalyst in the vanadium compound aqueous solution is preferably in the range of 0.5 minutes to 10 minutes.

  In the second drying step (S7), the denitration catalyst after the first active component impregnation step (S6) is dried at 105 ° C. for at least 4 hours. The drying temperature and drying time are not particularly limited as long as the drying temperature and drying time can sufficiently dry the denitration catalyst. More specifically, the drying temperature is preferably in the range of 90 ° C. or higher and 150 ° C. or lower. If the drying temperature is less than 90 ° C., the denitration catalyst may not be sufficiently dried. If the drying temperature exceeds 150 ° C., the processing equipment cost required for the first drying step increases. The drying time is preferably in the range of 1 hour to 10 hours. If the drying time is less than 1 hour, the denitration catalyst may not be sufficiently dried. If the drying time exceeds 10 hours, the cost of the processing equipment required for the first drying step increases. After the second drying step (S6), the regenerated honeycomb type denitration catalyst can be inserted into the denitration apparatus and used again.

  Hereinafter, the effects of the present invention will be clarified by specifically describing the present invention with reference to Examples. In addition, this invention is not restrict | limited by the following Example.

[Example 1]
(Adjustment of catalyst powder A)
Hydrolysis was performed by adding 4.4 l of 80 ° C. water to 337.6 g of Ti source (Ti (O—iC ₃ H ₇ ) ₄ ), followed by further aging by stirring in water at the same temperature for 2 hours. The produced sol was filtered, and the produced alcohol was sufficiently washed and dried, followed by heating at 500 ° C. for 5 hours and baking. TiO ₂ with a powder obtained after calcination, 100 parts by weight of TiO _2, ammonium metavanadate and _(NH 4 VO ₃₎ ammonium paratungstate a _{{(NH 4) 10 W 12} O 41 · 5H 2 O} V ₂ O ₅ is 5 parts by weight, WO ₃ is 8 parts by weight, dissolved in a 10% by weight methylamine aqueous solution, impregnated with TiO ₂ powder, dried, and calcined at 500 ° C. for 5 hours to obtain catalyst powder A Got.

(Adjustment of glass fiber A)
As the glass fiber A, E-Glass manufactured by Nittobo Co., Ltd., which does not contain ZrO ₂ and is used as a printed wiring board application, was prepared. Fiberglass _A contained _{SiO 2, B 2 O 3,} Al 2 O 3, CaO, MgO, and Na ₂ O and _{K 2} O. Each composition ratio of the glass fiber A is at a weight _{ratio, SiO 2: B 2 O 3} : Al 2 O 3: CaO and MgO: Na ₂ O and _{K 2 O = 52~56: 5~10:} 12~ It was 16: 20-25: 0-0-0.8.

(Adjustment of catalyst A)
Glass fiber A was added as a binder to catalyst powder A. The addition amount of the glass fiber A was 7 parts by weight with 100 parts by weight of the catalyst powder A. Further, 3 parts by weight of cellulose acetate as an organic plasticizer and an aqueous ammonia solution were added and kneaded. The kneaded product was extruded, dried, and fired at 500 ° C. for 5 hours to obtain a honeycomb-shaped catalyst A having pores with a lattice spacing of 7.5 mm and a wall thickness of 1.0 mm.

(Drug washing reprocessing)
It was installed in the actual machine of the power plant, and after operating the actual machine for 50000 hours, it was taken out from the actual machine and prepared. Then, it washed with water for 30 minutes using 14 to 18 degreeC water. The ratio of catalyst A to water was 1: 3. Then, it was immersed in 55 degreeC-65 degreeC NaOH aqueous solution for 1 hour. The ratio of catalyst A to aqueous solution was 1: 3. Subsequently, poppy immersed for 1 hour in 14 ° C. ~ 18 ° C. in _H 2 SO ₄ in aqueous solution. The ratio of catalyst A to aqueous solution was 1: 3. Subsequently, it was washed with water at 14 ° C. to 18 ° C. for 30 minutes. The ratio of catalyst A to water was 1: 3. Then, after drying about 4 hours at 105 ° C., and immersed for 1 minute in VOSO ₄ aqueous solution. Thereafter, the catalyst was taken out from the VOSO ₄ aqueous solution and dried at 105 ° C. for at least 4 hours. The dried catalyst was designated as catalyst A ′.

<Compressive strength test>
Changes in the compressive strength in the wall direction (kgf / cm ² ) after performing the chemical washing regeneration treatment on the catalyst A and the catalyst A ′ were examined. The compressive strength in the wall direction was measured using a Kiyama-type hardness meter manufactured by Fujiwara Seisakusho. The “wall direction compressive strength” means the compressive strength in the direction perpendicular to the gas flow.

FIG. 3 is a graph showing the compressive strength (kgf / cm ² ) in the wall direction of the catalyst A and the catalyst A ′ after the chemical washing regeneration treatment. As shown in FIG. 3, the compressive strength in the wall direction of the catalyst A not subjected to the chemical washing regeneration treatment was about 13 kgf / cm ² . On the other hand, the compressive strength in the wall direction of the catalyst A ′ subjected to the chemical washing regeneration treatment was 9 kgf / cm ² or less. From the results of the compressive strength test, it was found that the compressive strength of the catalyst was significantly reduced by performing the chemical washing regeneration treatment once.

[Example 2]
(Adjustment of glass fiber B)
As glass fiber B, AR-Glass manufactured by Nippon Electric Glass Co., Ltd., containing ZrO ₂ and used as a concrete reinforcing material, was prepared. Fiberglass _{B contained SiO 2, TiO 2, Al 2} O 3, CaO, MgO, Na 2 O, the _{K 2} O and ZrO _2. Each composition ratio of the glass fiber B is a weight ratio when the catalyst powder is 100, and SiO ₂ : TiO ₂ : Al ₂ O ₃ : CaO and MgO: Na ₂ O and K ₂ O: ZrO ₂ = 54 to 65 : 0 to 10: 0 to 2: 0 to 10:10 to 30:16 to 24.

(Adjustment of glass fiber C)
As glass fiber C, Cem-Fil manufactured by OWENS CORNING, which contains ZrO ₂ and is used as a concrete reinforcing material, was prepared. The glass fiber C contained at least SiO ₂ , Na ₂ O, K ₂ O, and ZrO ₂ . Each composition ratio of the glass fibers C was SiO ₂ : Na ₂ O and K ₂ O: ZrO ₂ = 62: 15: 17 in terms of weight ratio when the catalyst powder was 100.

<Alkali resistance test>
The glass fiber A to C was subjected to an alkali resistance test. 1.2 L of NaOH was filled in the beaker and heated to 60 ° C. Thereafter, 10 g of glass fiber A was added to the beaker, and the mixture was left for a predetermined time while maintaining a temperature of 60 ° C. This was used as a sample of glass fiber A. Samples were also prepared for glass fibers B and C in the same procedure. In addition, the alkali resistance test was performed by preparing samples for each predetermined immersion time with the immersion time as a parameter. Moreover, the elution amount (mg / L) of the fiber component of each sample and the elution amount (mg / L) for each fiber component were measured using a plasma emission analysis method (ICP).

  The results of the alkali elution test are shown in FIG. As shown in FIG. 4, the glass fiber A was immersed in an aqueous NaOH solution for 24 hours, so that a fiber component of 300 mg / L or more was eluted. Even when the glass fiber B was immersed in an aqueous NaOH solution for 20 hours, only a fiber component of 50 mg / L or less was eluted. Further, even when the glass fiber C was immersed in an aqueous NaOH solution for 24 hours, only a fiber component of 50 mg / L or less was eluted.

The breakdown of the fiber components eluted in the alkali dissolution test is shown in FIG. As shown in FIG. 5, in the glass fiber A, a fiber component of 50 mg / L or more was eluted only by being immersed in an aqueous NaOH solution for 1 hour, and a fiber component of 300 mg / L or more was eluted by being immersed for 24 hours. Among the fiber components eluted from the glass fiber A, B ₂ O ₃ and Al ₂ O ₃ were particularly eluted. B ₂ O ₃ of the glass fiber A was eluted by being immersed for 1 hour, and was eluted about 80 mg / L by being immersed for 24 hours. Al ₂ O ₃ of the glass fiber A was eluted by being immersed for 1 hour, and was approximately 100 mg / L by being immersed for 24 hours. Further, the glass fiber B and the glass fiber C hardly eluted the fiber component even when immersed in an aqueous NaOH solution for 1 hour, and the fiber component of about 50 mg / L eluted when immersed for 24 hours. The fiber component eluted from the glass fiber B and the glass fiber C was only SiO ₂ .

From the results of the alkali resistance test, the glass fiber A containing no ZrO ₂ elutes the fiber component only by immersing for 1 hour, while the glass fiber B and glass fiber C containing ZrO ₂ prevent the elution of the fiber component. all right. Thereby, it turned out that the glass fiber B and the glass fiber C have favorable alkali resistance with respect to the glass fiber A. That is, it was found that the glass fiber B and the glass fiber C can suppress the elution amount by about 100% under the condition of the first chemical washing treatment that is immersed for 1 hour at room temperature. Moreover, in order to further suppress the elution amount of the fiber component due to the immersion of the NaOH aqueous solution, it has been found effective to use, as a catalyst, glass fiber from which the fiber component is eluted in advance by being immersed in the NaOH aqueous solution. Further, it was found that the glass fiber A was also effective if it was used as a catalyst after washing with a NaOH aqueous solution. Furthermore, in order to further suppress the elution amount of the fiber component due to the immersion of the NaOH aqueous solution, it is effective to include B ₂ O ₃ in the glass fiber at 0 wt% or more and 5 wt% or less. It turns out that it is more effective not to include. Furthermore, it has been found that it is effective to include Al ₂ O ₃ in the glass fiber at 0 wt% or more and 2 wt% or less, and it is more effective not to include it substantially in the glass fiber.

[Example 3]
<Acid resistance test>
An acid resistance test was performed on the glass fibers A to C. The beaker was filled with 1.2 L of H ₂ SO ₄ and the temperature was raised to 60 ° C. Thereafter, 10 g of glass fiber A was added to the beaker, and the beaker was left for a predetermined time while maintaining a temperature of 60 ° C. After a predetermined time had passed, suction filtration was performed to take out the eluted fiber component. This was used as a sample of glass fiber A. Samples were also prepared for glass fibers B and C in the same procedure. The acid resistance test was carried out by preparing samples for each predetermined immersion time with the immersion time as a parameter. Moreover, the elution amount (mg / L) of the fiber component of each sample and the elution amount (mg / L) for each fiber component were measured using a plasma emission analysis method (ICP).

The results of the acid resistance test are shown in FIG. As shown in FIG. 6, the glass fibers _A, by aqueous H 2 SO ₄ fiber component of about 100 mg / L is eluted by immersing 1 _hour, immersed for 24 hours in aqueous H 2 SO _4, 1600 mg / About L fiber components were eluted. On the other hand, even when the glass fiber B was immersed in an H ₂ SO ₄ aqueous solution for 24 hours, the fiber component was not eluted. The glass fiber C did not elute even when it was immersed in an aqueous solution of H ₂ SO ₄ for 1 hour, and it was immersed for 24 hours to elute a small amount of fiber component.

A breakdown of the fiber components eluted in the acid resistance test is shown in FIG. As shown in FIG. 7, in the glass fiber A, B ₂ O ₃ , Al ₂ O ₃ and CaO were particularly eluted. B ₂ O ₃ of glass fiber A was eluted by being immersed for 1 hour, and was approximately 300 mg / L by being immersed for 24 hours. Al ₂ O ₃ of glass fiber A elutes by being immersed for 1 hour, about 900 mg / L is eluted by being immersed for 24 hours, and CaO of glass fiber A is eluted by being immersed for 1 hour for 24 hours. About 300 mg / L was eluted by immersion. On the other hand, the component eluted from the glass fiber B and the glass fiber C was only a slight amount of SiO ₂ eluted from the glass fiber C immersed in an aqueous solution of H ₂ SO ₄ for 24 hours.

From the results of the acid resistance test, the glass fiber A containing no ZrO ₂ dissolves the fiber component only by being immersed for 1 hour, while the glass fiber B and the glass fiber C containing ZrO ₂ prevent the elution of the fiber component. all right. Thereby, it turned out that the glass fiber B and the glass fiber C have favorable acid resistance with respect to the glass fiber A. That is, it was found that the glass fiber B and the glass fiber C can suppress the elution amount by about 100% under the condition of the second chemical washing treatment that is immersed for 1 hour at room temperature. Further, in order to further suppress the elution amount of the fiber component due to the immersion of the aqueous H ₂ SO ₄ solution after the immersion of the NaOH aqueous solution, it is necessary to use glass fibers that are preliminarily immersed in the aqueous H ₂ SO ₄ solution and the fiber component is eluted. It turned out to be effective. Further, it has been found that the glass fiber A is also effective if it is used by catalyzing what is washed with an aqueous NaOH solution and / or an aqueous H ₂ SO ₄ solution. Furthermore, in order to further suppress the elution amount of the fiber component due to the immersion of the aqueous H ₂ SO ₄ solution after immersion in the NaOH aqueous solution, in addition to Al ₂ O ₃ and B ₂ O ₃ , CaO is added in an amount of 0 wt% or more and 10 wt% It was found that it was effective to be contained in the glass fiber at less than or equal to%, and it was more effective not to be substantially contained in the glass fiber.

[Example 4]
(Adjustment of catalyst B)
A honeycomb-shaped catalyst B was prepared by the same procedure as the catalyst A except that the glass fiber B was added as a binder to the catalyst powder A. The addition amount of the glass fiber B was 7 parts by weight with 100 parts by weight of the catalyst powder A.

(Adjustment of catalyst C)
A honeycomb-shaped catalyst C was prepared by the same procedure as that for the catalyst A except that the glass fiber C was added as a binder to the catalyst powder A. The addition amount of the glass fiber C was 7 parts by weight with 100 parts by weight of the catalyst powder A.

<Comparative test of compressive strength>
From the results of the alkali resistance test and acid resistance test, when the above-described chemical washing regeneration treatment is performed once for the catalyst A containing glass fiber A, the catalyst B containing glass fiber B, and the catalyst C containing glass fiber C The wall direction compressive strength (N / cm ² ) relative to the total elution amount (mg / L) of fiber component was estimated. The compressive strength with respect to the total elution amount of the fiber component was measured using the above-mentioned Kiyama altimeter.

FIG. 8 shows a trial calculation result of the compressive strength in the wall direction (N / cm ² ) with respect to the total elution amount of the fiber component (mg / L) for Catalyst A to Catalyst C. In addition, the broken line in FIG. 8 has shown the initial compressive strength. As shown in FIG. 8, the wall direction compressive strength of the catalyst A is 9.7 N / cm ² , the wall direction compressive strength of the catalyst B is 11.7 N / cm ² , and the wall direction compressive strength of the catalyst C is 11 0.9 N / cm ² . That is, in the catalyst A that was subjected to the chemical washing regeneration treatment once, the compressive strength in the wall direction was reduced by about 21%. The catalyst B that had been subjected to the chemical washing regeneration treatment once had a wall direction compressive strength reduced by about 5%. Moreover, the catalyst C which performed the chemical | medical-washing reproduction | regeneration process once was that the wall direction compressive strength fell about 3%.

From the calculation results of the compressive strength, the glass fiber B containing ZrO ₂ and the catalyst B and the catalyst C using glass fiber C as the binder are compared with the catalyst A using the glass fiber A not containing ZrO ₂ as the binder. It was found that a decrease in compressive strength after the regeneration process can be prevented. More specifically, the catalyst B using the glass fiber B as the binder can suppress a decrease in strength of about 16% than the catalyst A, and the catalyst C using the glass fiber C as the binder is about 18% more than the catalyst A. It was found that the strength reduction can be suppressed. Moreover, it turned out that the catalyst B and catalyst C which consist of glass fiber B and glass fiber C can suppress the fall of intensity | strength within the range of 3%-5%, even if it implements chemical washing reproduction | regeneration processing. Thereby, it turned out that the catalyst B and the catalyst C can be suitably reused as a regenerated denitration catalyst by the chemical washing regeneration treatment.

[Example 5]
<Catalytic friction coefficient comparison test>
From the results of the alkali resistance test and the acid resistance test, the wear rate (%) with respect to the total elution amount (mg / L) of the fiber component when the chemical washing regeneration treatment is performed once for the catalyst A, the catalyst B, and the catalyst C. Was estimated. The wear rate with respect to the total elution amount of the fiber component was calculated by injecting silica sand into air gas and allowing it to flow through the catalyst for a certain period of time, and calculating the wear difference before and after the flow.

  FIG. 9 shows the result of trial calculation of the wear rate (%) of the catalyst with respect to the total elution amount (mg / L) of the catalyst A to the catalyst C. In addition, the broken line in FIG. 9 has shown the initial amount of wear. As shown in FIG. 9, the friction coefficient of the catalyst A increased by about 2.1%. On the other hand, the wear rate of catalyst B was only increased by about 0.6%, and the wear rate of catalyst C was only increased by about 0.1%.

From calculation results of the compressive strength, the catalyst B and catalyst C was glass fiber A containing ZrO ₂ as a binder, rather than catalyst A in which the glass fibers A without ZrO ₂ and binder, the coefficient of friction due to chemical washing regeneration process I found that I could prevent the rise. Further, it was found that the catalyst B and the catalyst C composed of the fiber B and the glass fiber C can suppress the increase in the wear rate within the range of 0.1% to 0.6% even when the chemical washing regeneration treatment is performed. . Thereby, it turned out that the catalyst B and the catalyst C can be suitably reused as a regenerated denitration catalyst by the chemical washing regeneration treatment.

  According to the honeycomb type denitration catalyst according to the present invention, it is possible to suppress the strength reduction of the denitration catalyst during the chemical washing regeneration process for catalyst regeneration. Moreover, the denitration catalyst that has been subjected to the chemical washing regeneration treatment can be repeatedly regenerated and reused in the actual machine.

1 Denitration catalyst 1a Pore

Claims (7)

To the denitration catalyst powder containing at least TiO ₂ ,
A honeycomb comprising: SiO ₂ as an essential component, and glass fibers containing ZrO ₂ and an oxide of one or more elements selected from the group consisting of Ti, Mg, Na and K as other components Type denitration catalyst. The honeycomb type denitration catalyst according to claim 1, wherein a content of B ₂ O ₃ in the glass fiber is 0 wt% or more and 5 wt% or less.   The honeycomb type denitration catalyst according to claim 2, wherein the glass fiber does not contain CaO.   The honeycomb type denitration catalyst according to any one of claims 1 to 3, wherein the addition amount of the glass fiber is 1 part by weight or more and 10 parts by weight or less based on 100 parts by weight of the denitration catalyst powder. . 5. The honeycomb type denitration catalyst according to claim 1, wherein a content of ZrO ₂ in the glass fiber is 16 wt% or more and 24 wt% or less. The glass fiber has a SiO ₂ content of 54 wt% to 65 wt%, a TiO ₂ content of 0 wt% to 10 wt%, and an MgO content of 0 wt% to 10 wt%. % or less, and the it is 10 wt% to 30 wt% content of Na ₂ O, according to claim 5, the content of _{K 2} O is characterized in that 30% by weight or less than 10 wt% Honeycomb type denitration catalyst. The denitration catalyst powder, the TiO ₂ as a carrier, honeycomb denitration according to any one of claims 1 to 6, characterized by comprising carrying V ₂ O ₅ and / or WO ₃ as the active ingredient catalyst.

Images