KR102081628B1 - A Method for Manufacturing SCR Catalyst Using Waste SCR Catalyst - Google Patents

Abstract

The present invention relates to a method for producing an SCR catalyst using an SCR waste catalyst, and more particularly, a SCR waste catalyst that is broken or unable to be further regenerated to remove foreign substances, pulverize and slurry, and then press or coat it on a support. By producing a new type of SCR catalyst, it is not possible to regenerate it, thereby reducing the waste of the catalyst that is disposed of, thereby reducing waste disposal costs, preventing environmental pollution, and replacing waste denitrification SCR catalysts at low cost. There is an effect that can be done.

Description

A method for manufacturing scr catalyst using waste scr catalyst

The present invention relates to a method for producing an SCR catalyst using an SCR spent catalyst. More particularly, the present invention relates to an SCR catalyst which is applied to the removal of nitrogen oxides and recovers the SCR spent catalyst at the end of its life and exhibits the activity of the catalyst prior to its disposal. It is related with the manufacturing method.

Exhaust gases from coal-fired power plants, coal-fired power plants, and / or incinerators generally contain large amounts of harmful substances such as sulfur oxides, nitrogen oxides, and dioxins. Selective Catalytic Reduction (SCR) using NH ₃ as a reducing agent has been widely applied.

In particular, the nitrogen oxide discharge facilities such as coal-fired power plants, coal-fired power plants, and incinerators in Korea have already installed or are planning to install the above-described SCR denitrification facilities. Increasingly stringent, there is an increasing number of applications of SCR denitrification systems to meet these emission regulations.

On the other hand, the catalyst installed to remove the nitrogen oxide in the SCR denitrification process is generally used honeycomb type (Plate type), plate type (Plate Type), metal foam (Metal foam) type, the catalyst active ingredient A small amount of vanadium (V ₂ O ₅ ) and tungsten (WO ₃ ) are mixed with titanium dioxide (TiO ₂ ) for extrusion molding, or a catalyst prepared by pressing or coating a metal support is used. These SCR catalysts are contaminated by a large amount of impurities and contaminants contained in the exhaust gas during the process of being installed and used in the SCR denitrification process, and thus the activity of the catalyst decreases over time. After three years the performance of the catalyst is substantially degraded or terminated.

Therefore, considering the general life cycle of the SCR catalyst installed in the SCR denitrification facility, the NOx can be reduced to less than the regulated value and discharged, the catalyst life is substantially terminated in the next 3 to 5 years. From then on, a considerable amount of waste denitrification SCR catalysts that have been installed and operated will continue to be generated.

Therefore, there is a need for a method of regenerating the SCR waste catalyst which regenerates the SCR waste catalyst so that the performance of the catalyst can be reused by regenerating the performance of the conventional catalyst. This is an urgent skill from the point of view.

Regeneration method of the SCR waste catalyst developed until recently is to remove foreign matters by passing gas with particulates through the through hole (see Patent Document 0001). The method to make it is examined, and it wash | cleans with water or the diluted inorganic acid aqueous solution, wash | cleans with 0.1 weight%-5 weight% oxalic acid aqueous solution, and also removes the acid which remains in a catalyst by water washing (refer patent document 0002), The method of regenerating catalyst performance by washing | cleaning, such as the method of washing after wash | cleaning with water of 50 degreeC or more and 80 degrees C or less (refer patent document 0003), is examined.

However, according to the regeneration method of the SCR waste catalyst, especially in the case of a honeycomb catalyst, the catalyst itself is easily damaged by impacts such as bubbling and ultrasonic vibration during cleaning, and also by contact with an acid aqueous solution. If the strength of the support is weakened due to the impossibility of repetitive regeneration of two or more times, or the SCR waste catalyst, which is difficult to further regenerate, it is discarded in its entirety, which causes serious problems in terms of waste disposal cost and environmental pollution.

Japanese Laid-Open Patent No. 1995-116523 (published: 1995.05.09) Japanese Patent No. 3150519 (published: 1995.08.22) Japanese Patent Publication No. 1996-196920 (published: 1996.08.06)

The main object of the present invention is to solve the above-described problems, the present invention is to recover the SCR waste catalyst, especially honeycomb type SCR waste catalyst that is broken or impossible to regenerate, to remove the foreign matter and pulverize the slurry and then to the support By manufacturing the SCR catalyst by pressing or coating, it is possible to reduce the amount of waste of the SCR waste catalyst which is entirely discarded by the existing regeneration method, and at the same time, to provide an economical method for producing the SCR catalyst compared to the cost of producing a new catalyst.

In order to achieve the above object, one embodiment of the present invention comprises the steps of (a) washing the SCR spent catalyst; (b) drying the washed SCR spent catalyst and then grinding to obtain a catalyst powder; (c) mixing a binder, a dispersant and a solvent with the pulverized catalyst powder to obtain a slurry; (d) pressing or coating the obtained slurry on a support to obtain a catalyst structure; And (e) drying the catalyst structure, and then calcining; provides a method for producing an SCR catalyst using an SCR spent catalyst comprising a.

In a preferred embodiment of the present invention, the drying of step (b) may be characterized in that performed for 1 hour to 3 hours at 90 ℃ ~ 120 ℃.

In a preferred embodiment of the present invention, the step (b) may be characterized in that it further comprises the step of baking for 1 hour to 5 hours at 400 ℃ ~ 500 ℃ after drying.

In a preferred embodiment of the present invention, the step (c) is 30 wt% to 45 wt% of the catalyst powder, 3 wt% to 10 wt% of the binder, 3 wt% to 10 wt% of the dispersant solvent It can be characterized by mixing in.

In a preferred embodiment of the present invention, the catalyst structure of step (d) may be characterized in that the shape is selected from the group consisting of a plate, metal foam and metal waveform.

In a preferred embodiment of the present invention, the firing of step (e) may be characterized in that performed for 1 hour to 5 hours at 400 ℃ ~ 500 ℃.

SCR catalyst production method using the SCR waste catalyst according to the present invention by recovering the SCR waste catalyst that is damaged or unable to further regeneration to remove foreign matter, pulverized and slurry, and then compressed or coated on a support to prepare the SCR catalyst In addition, it is possible to further reduce the waste of the catalyst to be disposed of because it is not possible to regenerate, reduce the waste disposal costs, prevent environmental pollution, and can replace the waste denitrification SCR catalyst at a low cost.

1 is a flowchart illustrating a method for preparing an SCR catalyst using an SCR spent catalyst according to the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

Throughout this specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding the other components unless otherwise stated.

The present invention comprises the steps of (a) washing the SCR spent catalyst; (b) drying the washed SCR spent catalyst and then grinding to obtain a catalyst powder; (c) mixing a binder, a dispersant and a solvent with the pulverized catalyst powder to obtain a slurry; (d) pressing or coating the obtained slurry on a support to obtain a catalyst structure; And (e) drying the catalyst structure, and then firing; relates to a method for producing an SCR catalyst using an SCR spent catalyst comprising a.

Substantially end-of-life catalysts, in particular SCR catalysts, according to the present invention are subjected to prolonged exposure to impurities and contaminants contained in the exhaust gas during their application to SCR denitrification equipment for removing nitrogen oxides. When the activity of the catalyst means that the catalyst at the point that does not achieve the target reduction rate of nitrogen oxides in the equipment is applied, which can be generally referred to as SCR waste catalyst, in the present invention the SCR waste catalyst substantially This can be regarded as the same as the catalyst whose end of life or activity is significantly reduced, ie SCR catalyst.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, the following description is only for explaining the present invention specifically, and is not limited to the scope of the present invention by the following description.

1 is a flow chart illustrating a method for producing an SCR catalyst using an SCR spent catalyst according to the present invention.

In the SCR catalyst preparation method using the SCR waste catalyst according to the present invention, washing is first performed to remove impurities or contaminants attached to the SCR waste catalyst [Step (a)].

SCR waste catalyst according to the present invention is applied to the SCR denitrification equipment for removing nitrogen oxides, the washing step to remove such impurities or contaminants as long time exposure to impurities or contaminants contained in the exhaust gas. To perform.

The washing step may be carried out by repeatedly immersing water, preferably at room temperature, distilled water or the like to remove impurities and contaminants, and washing the high-pressure air before the washing step, if the degree of contamination is serious. g. 0.1 kg / cm ² The contaminant may be removed with air injected at a pressure of from 0.5 kg / cm ² , followed by a washing step. In addition, it may be immersed in a dilute acid solution of pH 2.5 ~ 4.5 containing sulfuric acid, nitric acid, and then washed several times with distilled water, etc., during or after the washing step in addition to the ultrasonic wave or an additional ultrasonic cleaning step. It may also include. In this case, the ultrasonic cleaning step may be cleaned by soaking the SCR waste catalyst in distilled water, using ultrasonic waves of 28 kHz to 100 kHz for 1 to 30 minutes.

Meanwhile, the SCR waste catalyst recovered before the washing step may further include cutting the SCR waste catalyst into a predetermined size in order to easily perform the steps of washing, drying, and pulverization described below. In particular, the honeycomb-type SCR waste catalyst has a rectangular column shape, and a plurality of gas flow paths having a polygonal cross section, such as a square, a hexagon, or a triangle, are formed therein. It can be cut appropriately in consideration of equipment and the like. For example, the predetermined size at which the honeycomb type SCR waste catalyst is cut may be 3 cm to 10 cm × 3 cm to 10 cm × 5 cm to 50 cm, but is not limited thereto.

Thereafter, the washed honeycomb-type SCR waste catalyst is dried to remove moisture and then pulverized to obtain a catalyst powder [step (b)].

The drying may be performed for 1 hour to 3 hours at 90 ℃ ~ 120 ℃. The washed SCR catalyst is sufficiently dried within this drying range to prevent agglomeration from occurring in the milling process and to prevent loss of yield of catalyst powder of the desired size.

On the other hand, in the case of the SCR waste catalyst used in heavy oil, such as bunker seed oil, carbon is deposited on the surface of the catalyst to block the catalyst pores, and thus, after the above-mentioned drying step, an additional heat treatment step is performed to remove carbon on the surface of the catalyst. Can be done. At this time, the heat treatment may be baked for 1 hour to 5 hours at 400 ℃ ~ 500 ℃.

If the heat treatment is performed at 400 ° C. or less than 1 hour, the carbon deposited on the SCR spent catalyst cannot be completely removed, and if it is more than 500 ° C. or 5 hours, titanium dioxide, a support component, is phase-transferred and the catalyst Can reduce activity.

The dried SCR spent catalyst may be ground to a size suitable for producing a catalyst structure pressed or coated on a support, preferably 75 μm to 150 μm. In this case, when the average particle size of the pulverized catalyst powder is out of the range, a problem may occur that causes an increase in pulverization cost or a slurry is not easily formed, thereby making it difficult to compress or coat the catalyst on the catalyst structure. have.

 As the grinding method, any known method such as a ball mill and a vibration mill can be used without limitation.

Thereafter, the pulverized catalyst powder is slurryed by mixing a binder, a dispersant, and a solvent (step (c)).

The slurry may be mixed with 30 wt% to 45 wt% of catalyst powder, 3 wt% to 45 wt% of binder, 3 wt% to 10 wt% of dispersant, and distilled water, which is a solvent, wherein the solvent May be added in an amount of 35 wt% to 60 wt% based on the total weight of the slurry.

When the catalyst powder is mixed at less than 30% by weight of the slurry, the solid content of the slurry is low, so the coating must be repeated several times. If the catalyst powder exceeds 45% by weight, the slurry solid content is rather increased. This high difficulty in coating a uniform thickness on the catalyst support and a long drying and firing time may occur.

In addition, when the binder is less than 3% by weight based on the total weight of the slurry, the binder lacks adhesive force, which is likely to detach from the metal support after pressing or coating the support of the slurry. This can lead to a decrease in catalyst performance.

In addition, the dispersing agent, when mixed at less than 3% by weight relative to the total weight of the slurry, cannot perform uniform mixing of the slurry, and when it exceeds 10% by weight, it is difficult to compress or coat the support of the slurry, and to dry and fire Problems that take longer can occur.

In addition, the SCR catalyst production method using the SCR spent catalyst according to the present invention is prepared by further mixing the catalytic active components and cocatalyst components such as vanadium, tungsten, molybdenum in order to increase the denitrification catalytic activity when the slurry is prepared It may be used in combination with the novel catalyst material.

The slurry to be mixed as described above is compressed or coated onto a support to obtain a catalyst structure [step (d)].

The catalyst structure may be in the form of a plate, foam, wave, or the like, and preferably, may be a catalyst structure in which a slurry is coated on a flat support. The support may be a metal such as a metal plate, a foamed metal foam, or a metal corrugate, and the like, and may be a support commonly used in an SCR catalyst.

Thereafter, the obtained catalyst structure is dried and then calcined to prepare an SCR catalyst [step (e)].

 The drying is mainly to remove the solvent used in the preparation of the catalyst slurry, the obtained catalyst structure is dried for 1 to 3 hours at 90 ℃ ~ 120 ℃ using hot air, constant temperature and humidity or microwave (microwave) A catalyst structure free of cracks can be obtained.

In addition, the dried catalyst structure is calcined for 1 hour to 5 hours at 400 ℃ ~ 500 ℃. This serves to maximize the activity of the catalyst by optimizing the pore structure and specific surface area by removing the binder and dispersant components used in slurry preparation.

In the firing step, when firing is performed at 400 ° C. or less than 1 hour, organic matters contained in the slurry may not be completely removed, which may affect catalyst performance, and firing may be performed in excess of 500 ° C. or 5 hours. When performed, there is a problem in that the support component is phase-transferred to lower catalytic activity.

The SCR catalyst prepared as described above contains 60% by weight to 80% by weight of titanium dioxide, 1% by weight to 10% by weight of vanadium, 1% by weight to 10% by weight of tungsten, thereby removing impurities that hinder catalyst activity, and It is possible to increase the amount of soluble catalyst raw materials without loss of the component acting as the active site and at the same time obtain excellent nitrogen oxide removal effect.

In addition, in the preparation method of the SCR catalyst using the SCR waste catalyst according to the present invention, in particular, the manufacturing method of the SCR catalyst using the honeycomb type SCR waste catalyst removes foreign substances by recovering the honeycomb type SCR waste catalyst which is broken or cannot be further regenerated. And then crushed and slurried, and then extruded or coated on a support to produce a new type of SCR catalyst, which reduces the waste disposal cost and reduces environmental pollution by reducing the waste of the catalyst that is not recycled. In addition to preventing, the waste denitrification SCR catalyst can be replaced at low cost.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples are merely examples to help understanding of the present invention, but the scope of the present invention is not limited thereto.

< Example  1>

Honeycomb type SCR waste catalyst (15 cm × 15 cm × 80 cm) whose denitrification efficiency was reduced to about 49% (350 ℃) at the Korea District Heating Corporation C branch cogeneration plant SCR facility was reduced to 8 cm × 8 cm × 12 cm. The cut honeycomb-type SCR spent catalyst was immersed in distilled water for 5 minutes and then washed three times. After washing, the honeycomb-type SCR waste catalyst was dried in a drier at 120 ° C. for 2 hours, and then ground in a ball mill to obtain a catalyst powder having an average particle size of 100 μm. 5.3 g of a binder, 5.1 g of a dispersant, and 51.5 g of distilled water were mixed with 38.1 g of the catalyst powder obtained above, and stirred for 1 hour to prepare a catalyst slurry. The prepared slurry was coated with a plate-like support (2.5 cm × 10 cm × 0.06 cm) at a thickness of 700 μm, dried at 120 ° C. for 2 hours, and then calcined at 470 ° C. for 2 hours to prepare a plate-shaped SCR catalyst.

< Comparative example  1>

Prepared in the same manner as in Example 1, but the slurry was changed to 27.4 g of catalyst powder, 4.2 g of binder, 4.1 g of dispersant and 64.3 g of distilled water to prepare a plate-type SCR catalyst.

< Comparative example  2>

Prepared in the same manner as in Example 1, but the slurry was changed to 47.8 g of catalyst powder, 5.6 g of binder, 5.4 g of dispersant and 41.2 g of distilled water to prepare a plate-shaped SCR catalyst.

< Comparative example  3>

Prepared in the same manner as in Example 1, but the slurry was changed to 38.2 g of catalyst powder, 2.6 g of binder, 4.2 g of dispersant and 55.0 g of distilled water to prepare a plate-shaped SCR catalyst.

< Comparative example  4>

It was prepared in the same manner as in Example 1, except that slurry preparation was changed to 38.1 g of catalyst powder, 11.6 g of binder, 4.2 g of dispersant, and 46.1 g of distilled water to prepare a plate-shaped SCR catalyst.

< Comparative example  5>

In order to compare the nitrogen oxide reduction performance of the plate catalyst prepared in Example 1 and Comparative Examples 1 to 4, the plate-type new catalyst used in domestic B thermal power plant was obtained and cut into 8 cm × 8 cm × 12 cm.

< Experimental Example  1>

In order to compare the nitrogen oxide reduction performance of the catalyst prepared in Example 1 with those of Comparative Examples 1 to 5, each catalyst was mounted in a fixed bed atmospheric pressure continuous reactor, and then the denitrification performance was measured at 300 ° C. to 400 ° C. It was. The composition of the gas is 200 ppm NO gas (Sungkang Specialty Gas, 10% in N ₂ balance), 500 ppm SOx gas, and the reducing agent NH ₃ Gas (Sungkang Specialty Gas, 10% in N ₂ balance) is NO gas and molar ratio 240 ppm was injected quantitatively at 1: 1.2, and the concentration of O ₂ Gas (Sungkang Specialty Gas, 99.9%) was maintained at 3%. The surface velocity was maintained at 51m / h, the temperature was raised at a constant rate, and after the stabilization time of 30 minutes and the temperature and flow rate were stabilized, the exhaust gas composition was measured and shown in Table 1 together with the denitrification conversion rate.

division 300 ℃ 350 ℃ 400 ℃  NO (ppm) % Conversion  NO (ppm) % Conversion  NO (ppm) % Conversion Example 1 59 71.0 50 75.0 51 74.5 Comparative Example 1 67 66.5 63 68.5 60 70.0 Comparative Example 2 75 62.5 72 64.0 69 65.5 Comparative Example 3 68 66.0 67 66.5 68 66.0 Comparative Example 4 81 59.5 73 63.5 71 64.5 Comparative Example 5 73 63.5 62 69.0 59 70.5

As shown in Table 1, the SCR catalyst of Example 1 showed better denitrification performance at 300 ° C. to 400 ° C., which is an active temperature range, compared to the new catalyst (Comparative Example 5) actually used in thermal power plants. It was found that the denitrification performance of the 1 to 4 catalysts was low. Particularly in the case of a catalyst having a high slurry content (Comparative Example 2) or a high amount of binder (Comparative Example 4), the denitrification performance was found to be remarkably deteriorated due to the loss of the non-homogeneous coating and catalyst active point as described above.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (6)

(a) washing the SCR spent catalyst;
(b) drying the washed SCR spent catalyst and then grinding to obtain a catalyst powder;
(c) mixing a binder, a dispersant and a solvent with the pulverized catalyst powder to obtain a slurry;
(d) pressing or coating the obtained slurry on a support to obtain a catalyst structure; And
(e) drying the catalyst structure and then firing the catalyst structure;
In the step (c), 30 wt% to 45 wt% of the catalyst powder, 3 wt% to 10 wt% of the binder, and 3 wt% to 10 wt% of the dispersant are mixed in the solvent, and the binder and the dispersant Method (e) of producing a SCR catalyst using the SCR spent catalyst, characterized in that the removal after the firing step.
The method of claim 1,
The drying of the step (b) is a method for producing an SCR catalyst using the SCR waste catalyst, characterized in that performed for 1 hour to 3 hours at 90 ℃ ~ 120 ℃.
The method of claim 1,
The step (b) after drying, further comprising the step of firing for 1 hour to 5 hours at 400 ℃ ~ 500 ℃ SCR catalyst manufacturing method using a spent catalyst, characterized in that the SCR catalyst.
delete The method of claim 1,
The catalyst structure of step (d) is a method for producing an SCR catalyst using the SCR spent catalyst, characterized in that the shape selected from the group consisting of plate, foam and waveform.
The method of claim 1,
The firing of the step (e) is a method for producing an SCR catalyst using the SCR waste catalyst, characterized in that performed for 1 hour to 5 hours at 400 ℃ ~ 500 ℃.

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