KR102079475B1 - Fabrication method of SCR catalyst for removal of dioxin - Google Patents

Abstract

The present invention relates to a method for manufacturing an SCR catalyst for removing dioxin, and more particularly, to a method for manufacturing an SCR catalyst for removing dioxin, which has excellent adsorption performance and good reactivity. The method for manufacturing the SCR catalyst for removing dioxin according to the present invention comprises: a main raw material manufacturing step; an inorganic binder manufacturing step; a mixture step; a water injection step; an active material input step; an additive input step; an ammonia mixing step; a glass fiber input step; a sludge step; a kneading step; a mixing step; an extrusion molding step; a drying step; and a firing step.

Description

Fabrication method of SCR catalyst for removal of dioxin

The present invention relates to a method for producing an SCR catalyst for dioxin removal, and more particularly, to a method for producing an SCR catalyst for dioxin removal having excellent adsorption performance and good reactivity.

Exhaust gases from combustion plants such as industrial waste, municipal waste, steel manufacturing plants, and metal refining processes are not only sulfur oxides (SOx), nitrogen oxides (NOx), and chlorine, but also some of the toxic organic chlorides such as dioxins, PCBs, and chlorophenols. It contains a quantity.

In particular, dioxin, which is known as a highly toxic substance that causes various cancers and birth defects, is mainly generated during incineration of chemical wastes containing dioxin precursors such as municipal waste and medical waste in incinerators such as waste incinerators and resource recovery facilities. Dioxin, commonly referred to as dioxin, is composed of two benzene rings substituted with chlorine atoms and two oxygen-linked dioxin compounds (PCDD; Polychlorinated Dibenzo-p-Dioxin) and one oxygen atom (PCDF; Polychlorinated Dibenzo Furan). It is divided into types. Dioxin has 75 dioxins and 135 isomers according to the position and number of substituted chlorine atoms, and there are a total of 210 dioxins. Of these, the type of dioxin that is extremely toxic and persistent to humans and the environment is known as 2,3,7,8-TCDD. Dioxins are considered to be the most problematic chemicals that cause environmental pollution because they are fairly stable, insoluble substances and their toxicity continues to exist. The production of dioxins during incineration and thermal processes is highly dependent on temperature, chlorine concentrations (HCl, Cl2), oxygen and carbon monoxide concentrations. The optimum temperature for the production of dioxins by de novo synthesis is about 250. It is -450 degreeC, and dioxin decomposes at the temperature of 600 degreeC or more.

Techniques for controlling dioxins generated in incinerators can be classified into pre-treatment and post-treatment techniques. Pre-treatment techniques are technologies that reduce dioxins by pre-separation of waste, structural change of the combustor, and optimization of combustion conditions. It is practically impossible to completely control the production of dioxin. Therefore, in order to efficiently control dioxin, post-treatment technology capable of efficiently removing synthesized dioxin along with the development of pretreatment technology is required.

Post-treatment techniques include catalytic oxidative decomposition, thermal incineration and decomposition and adsorptive separation techniques.

Catalytic oxidative decomposition is a technique of decomposing dioxins into substances such as CO ₂ , H ₂ O, HCl by contacting exhaust gas with a catalyst. Thermal incineration and decomposition technology is a technology that decomposes dioxin by reheating the exhaust gas to a high temperature of 1000 ° C. or higher, but requires enormous energy cost and device cost. Adsorption separation technology is a method of adsorption and removal of the exhaust gas by contact with the adsorbent, but there is a problem that causes secondary pollutants caused by the adsorbent regeneration and waste adsorbent treatment. Therefore, catalytic oxidation decomposition method is the most researched technology in recent years.

In the process of preparing a catalyst to decompose the conventional dioxin, a solid phase raw material is added to a dry mixer, followed by mixing for a predetermined time to add moisture and other additives. Then, the dry mixed raw materials were added to the wet mixer and mixed for a predetermined time, and moisture and other additives were added according to the standard operating procedure, and the mixture was withdrawn after a predetermined time.

Patent Publication No. 2001-0018330 (published March 05, 2001) Registered Patent No. 10-0632591 (Registration date September 28, 2006) Patent Registration No. 10-0495789 (Registration Date June 08, 2005) Patent Registration No. 10-0703630 (Registration Date March 29, 2007)

When the catalyst is prepared by the conventional manufacturing method, the nonuniformity of the dough is generated according to the water content contained in the raw material due to the addition of a certain amount of water. Due to the non-uniformity of the dough, not only cracking of the catalyst occurs, but also a problem in that productivity is reduced due to poor moldability.

In addition, there is a problem in that the cost is increased because additional personnel are required for the kneading process to uniform the dough.

The present invention is to solve the above problems. An object of the present invention is to provide a method for preparing a catalyst that can uniformly control the moisture content to prevent uniform cracking of the catalyst and increase moldability.

SCR catalyst production method for dioxin removal according to the present invention, the main raw material manufacturing step, inorganic binder manufacturing step, mixture step, water input step, active material input step, additive input step, ammonia mixing step, glass fiber It includes a dosing step, a sludge step, a kneading step, a kneading step, an extrusion molding step, a drying step and a firing step. The main raw material manufacturing step is a mixture of 10 to 40% by weight of alumina (Al ₂ O ₃ ), 60 to 80% by weight of titania (TiO ₂ ), 0.1 to 3% by weight of molybdenum, 1 to 10% by weight of tungsten Make. The inorganic binder manufacturing step dissolves 5 to 20 wt% of the silica sol relative to the silica sol in 2 to 7 wt% of the silica sol relative to the main raw material. In the mixing step, the inorganic binder is added to the main raw material and mixed for 10 to 30 minutes to make a mixture. In the water input step, 20 to 40% by weight of water to the mixture is added to the mixture. The active material input step is 1 to 5% by weight of monoethanol compared to the main material of 1 to 5% by weight of the main material selected from one or more selected from ammonium metavanadate (NH ₄ VO ₃ ) and vanadium oxide (V ₂ O ₅ ) Dissolve in amine (Monoethanolamine) and add to the water mixture. The additive input step is 1 to 3% by weight of the cellulose binder compared to the main raw material, polyethylene glycol (Polyethylene glycol) and propylene glycol (Propylene glycol) and polyethylene oxide (Poly Ethylene Oxide) 1 to 2.5% by weight compared to the main raw material, glycerin ( Glycerin), stearic acid (Stearic Acid) and stearyl alcohol (Stearyl Alcohol) of 1 to 2.5% by weight of the additive to the active material is added to the mixture of the active material. In the ammonia mixing step, 3 to 5% by weight of ammonia water relative to the main raw material is added to the mixture into which the additive is added and mixed for about 60 to 120 minutes. The glass fiber input step is 5 to 15% by weight of the glass fiber compared to the main raw material in the mixed ammonia water. In the sludge step, 10 to 20% by weight of water is added to the mixture into which the glass fiber is added, and mixed for 30 to 90 minutes to sludge. In the kneading step, the sludge is adjusted to a water content of 17 to 33% to form a dough. The kneading step kneads the dough. In the extrusion molding step, the kneaded dough is extruded into an extruded body. The drying step is to dry the extruded body. In the firing step, the dried extrudate is fired.

In addition, in the method of manufacturing the SCR catalyst for dioxin removal, in the inorganic binder manufacturing step, the silica sol has a silica content of 10 to 30%, and the silica powder has a particle size of 3 to 7 micrometers. Do.

In addition, the SCR catalyst production method for the dioxin removal, the step of passing through the kneading dough kneaded in a stainless steel mesh mesh size of 1 to 3 millimeters further comprises a filtering step of removing foreign matter inside the dough. desirable.

In addition, in the method of preparing the SCR catalyst for dioxin removal, in the drying step, it is preferable to dry the extruded product at 50 to 110 degrees Celsius for 24 to 72 hours using a microwave.

In addition, in the SCR catalyst manufacturing method for dioxin removal, in the firing step, the dried extruded body is preferably baked for 3 to 7 hours at 400 to 550 degrees Celsius.

In the case of the present invention, by using the powder of alumina and titania, the catalyst has a bimodal structure, thereby improving the adsorption capacity. In addition, according to the present invention it is possible to provide the optimum catalyst impregnated with the active metal by the addition of molybdenum, tungsten, which serves as a cocatalyst, it is excellent in dioxin removal ability in the low temperature, medium temperature, high temperature zone.

Moreover, according to this invention, uniformity of dough can be ensured by adjusting water content constant. This can increase productivity by preventing cracking and formability of the catalyst.

1 is a conceptual diagram of one embodiment of a method for producing a SCR catalyst for dioxin removal according to the present invention.

With reference to Figure 1 will be described an embodiment of the SCR catalyst manufacturing method for dioxin removal according to the present invention.

SCR catalyst production method for dioxin removal according to the present invention is the main raw material manufacturing step (S11), inorganic binder manufacturing step (S13), mixture step (S15), water input step (S17), and active material input step (S19) ), Additive addition step (S21), ammonia mixing step (S23), glass fiber input step (S25), sludge step (S27), kneading step (S29), kneading step (S31), filtering It includes a step (S33), an extrusion molding step (S35), a drying step (S37) and a firing step (S39).

Solid phase raw materials are added to the mixer to prepare a catalyst. Solid phase raw material is a basic raw material of the carrier used as the skeleton of the catalyst body of the SCR catalyst, and serves to increase the reaction area by supporting the active material and providing a high surface area. At this time, the solid material is composed of a main raw material and an inorganic binder.

Main raw material manufacturing step (S11) refers to the step of introducing the main raw material into the mixer. The main raw material is 10 to 40% by weight of alumina (Al ₂ O ₃ ), 60 to 80% by weight of titania (TiO ₂ ), 0.1 to 3% by weight of molybdenum, and 1 to 10% by weight of tungsten to prepare a main raw material. The main raw material thus consists of a dual carrier of titania and alumina. Among the carriers, titania is anatase-type crystal structure with a specific surface area of 60 to 120 m 2 / g, pore size of 140 to 190 kPa, and alumina to gamma alumina (r-Al ₂ 0 ₃ ). A raw material having a surface area of 120 to 190 m 2 / g and a pore size of 100 to 140 mm 3 is used. Molybdenum and tungsten are supported on double carriers of titania and alumina to serve as promoters.

The inorganic binder manufacturing step (S13) dissolves 5 to 20% by weight of silica powder relative to the silica sol in 2 to 7% by weight of silica sol relative to the main raw material. The inorganic binder is silica (SiO ₂ ) for increasing the strength of the catalyst carrier, and has a fine size having a particle size of 3 to 7 μm at 2 to 7 wt% of the main raw material of silica sol having a silica content of 10 to 30%. Dissolve 5 to 20% by weight relative to the silica sol of the silica powder.

In the mixing step (S15), the inorganic binder is added to a mixer into which the main raw material is added, followed by mixing for 10 to 30 minutes to make a mixture.

In the water input step (S17), 20 to 40% by weight of water is added to the mixer in which the mixture is made.

In the active material input step (S19), vanadium, which is an active material of the SCR catalyst, is input, and at least one selected from vanadium precursors, ammonium metavanadate (NH ₄ VO ₃ ) and vanadium oxide (V ₂ O ₅ ), is selected from 1 to 5 Dissolve 1% by weight to 1% by weight of monoethanolamine (Monoethanolamine) compared to the main raw material as a solvent and add to the mixer.

Additive input step (S21) is an organic binder cellulose binder (Cellulose binder) that is used to combine the ceramic raw material powder to facilitate the extrusion molding of the SCR catalyst with other additives 1 ~ 3% by weight compared to the main raw material, SCR catalyst extruded As a plasticizer to give plasticity to the molded product for easy molding, it selects one from polyethylene glycol, propylene glycol, and polyethylene oxide and selects 1 to 2.5% by weight of the main raw material. Lubricating lubricity to the dough to enable a smooth extrusion molding selected from one or more of glycerin (Slyric acid) and stearic acid (Stearic Acid) and stearyl alcohol (Stearyl Alcohol) 1 ~ 2.5% by weight compared to the main raw material To the mixture.

In the ammonia mixing step (S23), in order to control the pH (acidity) of the mixture, 60 to 30% by weight of ammonia (NH ₃ ) with ammonia (NH ₃ ) content of 3 to 5% by weight is added to the mixer. Mix for about 120 minutes.

Glass fiber feeding step (S25) is a filler that maintains the shape of the molded body by acting as a skeleton of the SCR catalyst carrier in the mixture of ammonia water is 5 ~ 15% by weight of the glass fiber having a particle size of 3 ~ 10 ㎛ compared to the main raw material Input.

Sludge step (S27) is 10 to 20% by weight of water compared to the main raw material to the mixture is mixed for 30 to 90 minutes to sludge the mixture into the glass fiber.

The kneading step (S29) is made of dough by adjusting the sludge with a moisture content of 17 to 33%. To produce the sludge at the desired moisture content, first heat it for 15 to 50 minutes using steam. After the heating is applied, the cover of the mixer is opened to remove the heat inside the mixing dough and cooled until the moisture content is 17 to 33%. When the moisture content of the finally cooled mixed dough is 17 to 33%, the extrusion dough is taken out from the mixer.

In the kneading step S31, the dough drawn out from the mixer is kneaded through a kneader.

The filtering step S33 removes the foreign matter inside the dough by passing the kneaded dough in the kneading step S31 through a stainless steel mesh mesh having a grid size of 1 to 3 mm.

Extrusion molding step (S35) is filtered to put the dough is removed foreign substances into a vacuum extruder to make a honeycomb-shaped extruded body.

Drying step (S37) is to dry the extruded body which is a catalyst body. The extruded body produced in the extrusion step (S35) is dried for 24 to 72 hours at 50 ~ 110 degrees Celsius using hot air, constant temperature and humidity, microwave. This is a step of removing the water used in the production of the catalyst body, by the combination of these methods can be produced dry support without cracks.

Firing step (S39) is subjected to a heat treatment to fire the dried catalyst body. Usually fired for 3 to 7 hours at 400 to 550 degrees Celsius. This optimizes the pore structure and specific surface area of titania and alumina, which are dual carriers used as the backbone of the catalyst, and crystallizes the oxides of vanadium, which is an active material supported on the carrier, and molybdenum, tungsten, etc. Optimize activity. In the support body made of the extruded body, the organic binder is burned away in the firing step (S39).

In the present embodiment it is possible to ensure the uniformity of the dough by ensuring a uniform mixing of the raw materials and additives and by adjusting the water content constant. In addition, productivity can be increased by preventing cracking of the catalyst and increasing moldability. In addition, the composite carrier of alumina and titania may have a bi-modal pore structure of a combination of macro and micro pores.

Claims (5)

The main raw material manufacturing step of making a main raw material by mixing 10 to 40% by weight of alumina (Al ₂ O ₃ ), 60 to 80% by weight of titania (TiO ₂ ), 0.1 to 3% by weight of molybdenum, and 1 to 10% by weight of tungsten ,
An inorganic binder manufacturing step of dissolving 5 to 20 wt% of the silica powder relative to the silica sol in 2 to 7 wt% of the silica sol relative to the main raw material;
A mixing step of adding the inorganic binder to the main raw material and mixing the mixture for 10 to 30 minutes to form a mixture;
A water input step of adding 20 to 40% by weight of water to the mixture with respect to the main raw material,
Dissolve 1 to 5% by weight of monoethanolamine (Monoethanolamine) in an amount of 1 to 5% by weight relative to the main material selected from at least one selected from ammonium metavanadate (NH ₄ VO ₃ ) and vanadium oxide (V ₂ O ₅ ). An active material input step of inputting the water input mixture,
1 to 3% by weight of the cellulose binder, 1 to 2.5% by weight of the main raw material selected from polyethylene glycol (Propylene glycol) and polyethylene oxide (Poly Ethylene Oxide), glycerin (Glycerin) and stearic acid ( An additive feeding step of adding 1 to 2.5% by weight of the additive to the mixture into which the active substance is added, compared to one or more selected main ingredients from stearic acid) and stearyl alcohol;
Ammonia mixing step of mixing 3 to 5% by weight of ammonia water compared to the main raw material into the mixture into which the additive is added and mixing for about 60 to 120 minutes;
Glass fiber input step of injecting 5 to 15% by weight of the glass fiber compared to the main raw material in the mixture of the ammonia water,
A sludge step of sludge mixing by mixing 10 to 20% by weight of water relative to the main raw material to the mixture into which the glass fiber is added and mixed for 30 to 90 minutes;
And kneading step of making the dough by adjusting the sludge to moisture content 17 ~ 33%,
A kneading step of kneading the dough;
An extrusion molding step of extruding the kneaded dough into an extruded body,
A drying step of drying the extruded body,
Dioxin removal SCR catalyst manufacturing method comprising the step of firing the dried extruded body. According to claim 1, In the inorganic binder manufacturing step,
The silica sol has a silica content of 10 to 30%, and the silica powder has a particle size of 3 to 7 micrometers, characterized in that the dioxin removal SCR catalyst manufacturing method. The method of claim 2,
The kneading step kneaded in the kneading step passing through a mesh size of 1 ~ 3 millimeters of stainless steel mesh filtering step of removing the foreign matter inside the dough further comprising the step of producing a SCR catalyst for dioxin removal. The method of claim 3,
The drying step is a method for producing SCR catalyst for dioxin removal, characterized in that for 24 to 72 hours to dry the extruded molded body at 50 to 110 degrees Celsius using microwave. The method of claim 4, wherein
The firing step is a method for producing SCR catalyst for dioxin removal, characterized in that the dried extrudate is calcined for 3 to 7 hours at 400 ~ 550 degrees Celsius.

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