KR100746704B1 - Manufacture of reacting media with carbon support impregrated metal catalyst and removing of nox using its media - Google Patents

Abstract

A method of preparing a reactive medium comprising a carbon support impregnated with a metal catalyst and a method for removing NOx by using the reactive medium are provided to complement and replace the selective catalytic reduction process by directly reducing NOx exhausted from actual combustion flue gas by using an inexpensive metal impregnated carbon support without using a reducing agent such as ammonia. A method of preparing a reactive medium for NOx removal comprising a metal catalyst impregnated on a carbon support comprises: adding 47.37 to 49.75 wt.% of water into 0.5 to 5.26 wt.% of a metal catalyst to prepare an aqueous solution; adding 47.37 to 49.75 wt.% of a carbon support into the aqueous solution; and impregnating the carbon support with the aqueous solution in a rotary vacuum dryer by controlling an impregnation temperature to a range from 25 to 90 deg.C, controlling an impregnation speed to a range from 40 to 100 rpm, and controlling an impregnation pressure to a range from 500 to 700 mmHg. A method for removing NOx in an oxygen-free gas by using the reactive medium comprises removing NOx by controlling an injection flow rate of combustion flue gas to a range from 10,000 to 30,000 hr^-1, and controlling an operating temperature of 450 deg.C or more in a reactive medium comprising a carbon support impregnated with a metal catalyst.

Description

Manufacture of reacting media with carbon support impregrated metal catalyst and removing of NOx using its media}

1 is a method of removing nitrogen oxide using a carbon catalyst impregnated carbon support.

2 is a combustion characteristic of Western Bacco activated carbon.

3 is a SEM analysis result of the metal impregnated sample according to the pressure change.

4 is a nitrogen oxide removal experiment apparatus.

5 is the removal of nitrogen oxides using cobalt-containing activated carbon in anoxic conditions.

Figure 6 removal of nitrogen oxides using cobalt-containing activated carbon in aerobic conditions.

Figure 7 is a long-term experiment to remove nitrogen oxides using cobalt-containing activated carbon under aerobic conditions (using 7wt% cobalt-impregnated activated carbon, 350 ℃, 4% oxygen).

<Description of the symbols for the main parts of the drawings>

Bomb: 1a, 1b, 1c, 1d

2a, 2b, 2c, 2d: 2-hole valve

3a, 3b, 3c, 3d: flow regulator

4a, 4b, 4c, 4d: check valve

5: gas mixer 6: preheater

7: heating furnace 8: reactor

9: temperature controller 10: 3 ball valve

11: dehumidifier 12: gas analyzer

Nitrogen oxides (NOx) collectively refer to various substances such as nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), dinitrogen monoxide (N ₂ O), nitrogen tetraoxide (N ₂ O ₄ ) and nitrogen pentoxide (N ₂ O ₅ ). Nitrogen oxides of interest in air pollution are nitrogen monoxide and nitrogen dioxide, the most frequently released form of nitrogen oxides into the atmosphere. Nitrogen oxide reduction techniques for fixed pollutants can be classified into pre-combustion denitrification by pretreatment of fuel, denitrification during combustion by improvement of combustion method and modification of combustion apparatus, and post-combustion denitrification by exhaust gas treatment.

Despite many efforts to remove nitrogen oxides emitted by the combustion of fuels in power plants, incinerators, boilers, and various combustors, there are two main reasons for the fact that the NOx removal technology of flue gas is still unsatisfactory. have. The first is that nitrogen monoxide is an insoluble substance and has a very low reactivity, and the second is that it is prevented from removing nitrogen monoxide by other components contained in flue gas, such as water and sulfur oxide heavy metals. For this reason, the removal of nitrogen oxides in flue gas is more difficult and expensive than removal of sulfur oxides.

Most of the currently installed furnaces are designed for the purpose of maximizing combustion efficiency, so the fuel mixing speed is fast and the simple furnace is installed and the installation cost is low. However, such a combustion device is inevitably discharged a considerable amount of nitrogen oxides because the fuel reacts rapidly at high temperature and high oxygen concentration. Nitrogen oxide reduction techniques in fixed sources include: 1) denitrification before combustion by the use of low nitrogen-containing fuels, 2) improvement of combustion conditions by modification of combustion methods and modification of combustion equipment, and 3) treatment of exhaust gases after combustion. There is a flue gas denitrification method. Among these, pre-combustion denitrification has limitations on economic efficiency and denitrification efficiency. Combustion condition improvement method is a method that reduces the amount of nitrogen oxide produced by changing operating conditions of an existing combustion furnace and can be applied economically and simply to an existing furnace. However, since there is a high possibility of adversely affecting the operating efficiency, the control of nitrogen oxides is mainly applied to improving combustion conditions and secondly to denitrification.

The flue gas denitrification method is useful when a higher removal efficiency is required than the above control method of combustion conditions, and is also used when a combustion condition improvement method such as nitrous oxide control discharged from a nitric acid manufacturing plant cannot be applied. In particular, as the removal efficiency of nitrogen oxides is high and the method can actively respond to the recently tightened emission regulations, as shown in Table 1, it is largely divided into a dry method and a wet method according to the use of the solution.

The wet method has the advantage of removing nitrogen oxide and sulfur oxide at the same time, and has been applied to the process of generating a small amount of nitrogen oxide, but since nitrogen monoxide has low solubility in water, nitrogen dioxide before absorbing nitrogen monoxide in aqueous solution It is costly in this process, and nitrogen trioxide and nitrogen tetraoxide are formed as by-products in the process of oxidizing with nitrogen dioxide, causing water pollution.

On the other hand, the dry method does not use a catalyst, but selectively catalytic reduction (SNCR: Selective Non-Catalytic Reduction) method that selectively reduces nitrogen oxide to nitrogen and water at a high temperature of 850 ~ 1050 ℃ and only by ammonia injection and at low temperature (150 ~ 450 ℃). Selective Catalytic Reduction (SCR) is used to reduce nitrogen oxides to nitrogen and water. The selective non-catalytic reduction method has the advantage of removing more than 50% of nitrogen oxides at a low cost, but the unreacted ammonia released forms ammonium salts, which can block the equipment at the rear of the reactor or cause corrosion problems. It is narrow and has difficulty in commercialization.

Therefore, the most advanced, safe and economical technology to remove nitrogen oxides generated from the fixed source is selective catalytic reduction method, and has the advantage that no additional post-treatment process is required because it shows the removal rate of more than 90%. There are a growing number of countries that employ them, and most research is focused on this method.

Selective catalyst reduction technology can be divided into the fields of catalyst development, reactor development, and process development according to operating conditions. The catalyst development part of these technologies is the core of the selective catalyst reduction technology, and it is a very important element technology because the developed catalyst characteristics can determine the remaining processes such as the location and temperature range of the selective catalyst reduction process. To date, hundreds of various catalysts have been proposed, ranging from noble metal catalysts to basic metal catalysts, and the most widely used catalysts are known as vanadium-based catalysts based on TIO2. The selective catalytic reduction process using a vanadium-based catalyst based on the Tiotou as a carrier has excellent performance, and is currently used as a commercial process for treating nitrogen oxide in combustion exhaust gas discharged from a large boiler such as a power plant.

However, even in the case of the vanadium catalyst which is used most often in the selective catalytic reduction process is expensive, and because ammonia is used as a reducing agent, there is a disadvantage that environmental pollution due to the toxicity of ammonia and a separate reducing agent storage tank must be installed. In addition, as the environmental regulations are gradually strengthened, there is a demand for technology development that can assist and replace a selective catalyst reduction device that is simple in operation and simple in operation for treating pollutants generated in small and medium boilers.

As part of the development of such alternative process, technology development was performed to directly remove nitrogen oxides without injecting a reducing agent such as ammonia based on carbon support. Park et al. [Colloid and Interface Science, 275 (2004) 590-595, 282 (2005) 124-127 and 292 (2005) 493-497] impregnated activated carbon fibers with metal catalysts such as silver, copper and nickel by electroplating. After the nitrogen monoxide removal performance experiment was performed at 500 ℃. In this study, the conversion rate (nitrogen removal rate) of nitrogen monoxide at 500 ℃ was 100%.

In this study, however, it was carried out at a high temperature of 500 ℃, and used expensive impregnated carbon fiber and complicated impregnation method such as electroplating method. Nitrogen monoxide removal experiments were performed at low flow rates (10 ml / min flow rate at 0.5 gram of catalyst). Therefore, there are many functional and economic problems to use as a commercial technology using the results of such research.

Table 1: NOx Removal Process from Flue Gas

designation principle Research Status Dry method Selective Catalytic Reduction (SCR) -NH ₃ as reducing agent-Selective reduction and removal of NOx on catalyst Practical step Non-Selective Catalytic Reduction (NSCR) -Using H ₂ , CO as reducing agent-Non-selective reduction of NOx on catalyst Stopped during bench trial Selective Non-Catalytic Reduction (SNCR) -Reduce removal of NOx by injecting NH ₃ under high temperature range and without catalyst Although there is a practical example, the denitrification efficiency is low. Catalytic Decomposition -Decomposition and remove NOx directly into N ₂ , O ₂ using catalyst at high temperature Laboratory research phase Activated Carbon Adsorption -Selective reduction of NOx by NH ₃ injection using activated carbon and adsorption removal of SOx Under pilot pilot Zeolite adsorption method -NOx adsorption using zeolite-based adsorbent Lab steps Absorption -Absorb and remove NOx and SOx using copper oxide solid absorber Development stop after pilot test Electron Beam Irradiation - alkali (NH ₃₎ to respond to the electron beam (corona discharge or plasma) to investigate active NOx, SOx with the injection half each solid material in the exhaust gas (NH ₄ NO ₃ Recover as (NH ₄ ) ₂ SO ₄ ) Under pilot pilot Wet method Redox method -Reduce and remove NOx by absorbed SOx using ammonia water as absorbent Lab steps Oxidative Absorption -Absorption of NOx and SOx simultaneously with alkali absorber with oxidizing agent Pilot test under O ₃ / NH ₃ water absorption solution Alkali absorption method -Absorption of NOx and SOx from alkaline absorbent liquid Low Absorption Rate, Unsuitable for Large Scale Devices Complex Salt Absorption -Absorbs SOx with EDTA / Sodium Sulfite Absorption and reduces NOx Under pilot test development

An object of the present invention devised to solve the above problems is to use a low-cost metal impregnated carbon support to directly reduce the nitrogen oxides emitted from the actual combustion flue gas without using a reducing agent such as ammonia, which is a selective catalyst reduction It is used as a technology to supplement and replace the process.

To this end, the use of inexpensive carbon supports and the coprecipitation method that simply impregnates the metal catalyst on the carbon supports were used, and commercialized by enabling the treatment of actual combustion flue gas in an operating area that can supplement and replace the selective catalyst reduction process. The purpose is to use it as a technology.

The present invention is characterized by removing the nitrogen oxide in the combustion flue gas without a reducing agent such as ammonia by using a metal catalyst impregnated in the carbon support.

Carbon-based materials, which are widely known as environmentally functional materials, are increasingly being used more importantly due to environmental pollution caused by industrial development. Among the carbon-based materials, activated carbon is widely used in applications such as gas separation, purification and removal, concentration, organic solvent recovery, heavy metal recovery and removal, and deodorization due to the characteristics of many pores and surface functional groups. Activated carbon generally changes its chemical and physical properties due to changes in surface functional groups, pore size, and pore distribution depending on raw materials, manufacturing process, manufacturing method and post-treatment process. Can change. Carbon adsorbents are difficult to physically adsorb and remove low molecular weight polar molecules such as ammonia, nitrogen oxides, and sulfur oxides, and thus have low processing efficiency. If the surface of activated carbon is treated with a metal component that is advantageous for the treatment of high concentration of nitrogen oxides, although the treatment efficiency is low, it is primarily removed by the nitrogen oxide removal capability of the carbon adsorbent, and the surface treated metal doubles the performance of nitrogen oxide removal. It can be predicted that the oxide removal efficiency is soaring. Carbon, which is the main component of activated carbon, can remove nitrogen oxides due to its self-reducing ability when reacting with nitrogen oxides as follows, but the removal efficiency is low and is possible at high temperatures of 500 ° C. or higher.

NO (g) + C (s) ⇔ CO (s) + 1 / 2N ₂ (g) (1)

C-O (s) ⇔ CO (g) (2)

CO (s) + CO (g) ⇔ CO ₂ (g) + C (s) (3)

In order to process the combustion flue gas, the efficiency of nitrogen oxide treatment must be increased, and the reaction temperature must be lowered to the area where nitrogen oxide can be removed from the combustion flue gas containing oxygen. To this end, the metal catalyst was impregnated into the carbon support to increase the nitrogen oxide removal performance. At this time, when the metal is impregnated with activated carbon, for example, copper, nitrogen oxides are reduced by the following mechanism, which is shown in FIG. 1.

NO (g) + CS-2Cu (s) ⇔ CS-Cu ₂ O (s) + 1 / 2N ₂ (g) (4)

NO (g) + CS-Cu ₂ O (s) ⇔ CS-2Cu (s) + 1 / 2N ₂ (g) + CO ₂ (g) (5)

Here, CS (Carbon Support) means carbon support, (g) means gas state, and (s) means solid state.

That is, the introduced nitrogen oxides are simultaneously reduced and removed by a metal catalyst having a reducing ability of carbon itself serving as a metal catalyst support and carbon, and having a better reducing ability than carbon. In the above reaction, the nitrogen oxide can be reduced to nitrogen and oxygen by a catalytic action such as activated carbon, and generates carbon monoxide and carbon dioxide as reaction by-products.

In other words, the present invention relates to a method for preparing a metal-impregnated carbon support and an operation method for applying it to an actual combustion flue gas for removing nitrogen oxides from combustion flue gas without a reducing agent using a metal catalyst impregnated carbon support.

Preferably, in the present invention, after selecting a metal catalyst in a salt state capable of promoting the reduction of nitrogen oxides, the aqueous solution was prepared by adding 47.37 to 49.75 wt% of water to 0.5 to 5.26 wt% of the metal catalyst in a rotary vacuum dryer. Next, the carbon support 47.37 ~ 49.75wt% is further injected, the impregnation temperature is 25 ℃ to 90 ℃, the impregnation speed is 40 rpm to 100 rpm in order to impregnate the metal catalyst in the carbon support in the rotary vacuum dryer , Impregnation pressure is in the range of 500mmHg to 700mmHg to provide a method for producing a reaction medium consisting of a carbon support impregnated with a metal catalyst.

The present invention is also prepared by the above method, to provide a reaction medium for removing nitrogen oxides containing 90 to 99wt% of carbon support and 1 to 10wt% of metal catalyst.

The present invention also provides a method for removing nitrogen oxide using the reaction medium.

In the above invention, the carbon support for impregnating the metal catalyst is characterized in that it is based on a carbon component, and is mainly a carbon component by thermal decomposition (carbonization) of organic materials. Activated carbon, activated carbon fiber, coke, 촤, expansion Any one selected from graphite can be used. Among them, activated carbon and activated carbon fibers, which are materials having porosity through activation of carbon materials, can improve reactivity, which is more advantageous.

In the present invention, by impregnating the metal catalyst in the carbon support, it is possible to promote the reduction reaction of nitrogen oxide, and for this purpose, the impregnated metal catalyst may be copper, cobalt, iron, nickel, platinum, rhodium, silver, chromium, cerium, palladium, vanadium, Any one selected from ruthenium may be used. Moreover, two or more of these catalysts can be used in combination. Finally, inexpensive and highly reactive metals can be economically removed from these catalysts.

Preferably, when cobalt, copper, or iron is used as the impregnating catalyst for removing nitrogen oxides, Co (NO ₃ ) ₂ · 6H ₂ O, Cu (NO ₃ ) ₂ · 6H ₂ O, which is a hydrated salt, is used as the impregnating catalyst. , Fe (NO ₃ ) ₂ .6H ₂ O, respectively, or as a mixture thereof, in an amount of 47.37 to 49.75 wt% of water in the range of 0.5 to 5.26 wt% of the weight of the metal, prepared in an aqueous solution, and then injected into a rotary vacuum dryer. By adding 47.37 to 49.75 wt% of the carbon support, the metal catalyst can be impregnated with the carbon support.

In the above invention, the method of impregnating the metal catalyst to the carbon support is advantageous to use a simple impregnation device and simple operation of the coprecipitation method. The impregnation temperature is in the range of 25 ° C. to 90 ° C. at an impregnation rate. It is suitable to operate in the range of 40 rpm to 100 rpm, and the impregnation pressure in the range of 500 mmHg to 700 mmHg.

In the above invention, when the metal catalyst is impregnated in the carbon support, the impregnation ratio of the metal catalyst is suitably in the range of 1wt% to 10wt% compared to the carbon support. In particular, the optimum impregnation ratio is 7wt%, but the impregnation ratio may change slightly depending on the operating conditions such as the compositional characteristics of the flue gas and the change in the properties of the carbon support.

The carbon support in 30,000hr ^-1 range the flow rate of nitrogen oxide removal conditions of the reaction gas there is no oxygen in the case to remove the nitrogen oxides by the metal catalyst prepared in the above-mentioned invention, by using the impregnated carbon support from 10,000hr ^-1 When the metal catalyst impregnation is 7wt% or more, a conversion rate of 100% is obtained at a reaction temperature of 500 캜 or more.

The flow rate of the metal catalyst of the oxygen in the case to remove the nitrogen oxides by using the impregnated carbon support is a combustion gas at 1vol% 10vol% of nitrogen oxide removal of the invention from production conditions in the range of 30,000hr ^-1 10,000hr ^-1 When the carbon catalyst is impregnated with a metal catalyst of 7 wt% or more, a conversion ratio of 50% or more is obtained in a reaction temperature range of 300 ° C to 400 ° C.

Hereinafter, the present invention will be described in more detail with reference to Examples and Examples. However, these are not limited to the scope of the present invention by them as an embodiment of the present invention.

Reference Example 1

In the present invention, in order to manufacture a carbon support impregnated with a metal catalyst, a commercially available Westen baco granulated activated carbon made of coal having a low surface area and a wide surface area as a carbon support (American type, having a cylindrical shape of 4 mm in diameter and 150 mm in length). And physical properties thereof are shown in Table 2. In addition, copper, cobalt, and iron were selected as impregnation catalysts to impregnate the metal catalyst on the carbon support.

Table 2: Properties of Western Barco Activated Carbon

Loss on Drying (%) Iodine adsorption capacity (mg / g) Filling density (g / ml) Particle size (%) Hardness (%) Ash content (%) Specific surface area (m2 / g) Pore area (cc / g) 2.1 1041 0.36 93.9 98.6 6.5 1137 0.88

Reference Example 2

A thermogravimetric analyzer (SDT Q600, TA Co. USA) was used to determine the combustion characteristics under oxygen conditions for the activated carbon used as the carbon support in Reference Example 1. In the experiment, a sample of 20 mg or more was heated to a desired experimental condition in a nitrogen atmosphere flowing at a flow rate of 100 cc / min, and after reaching the temperature to be tested, the temperature was maintained for 20 minutes, and then the air was heated up to 900 minutes for 100 cc / min. Flow loss was observed at the flow rate. Experimental temperature was 300 ~ 450 ℃ and the interval was 50 ℃. The purpose of this study was to find out the consumption of activated carbon by injecting air containing 20.4% oxygen to make the conditions more intense than the flue gas containing 4% oxygen.

Figure 2 shows the combustion characteristics of the Westenbaco activated carbon, and despite the injection of oxygen at 300, 350 ° C does not burn and shows a slight combustion at 400 ° C. However, it is shown that rapid combustion occurs above 450 ° C. From the above results, it can be seen that when the catalyst using activated carbon as a support is reacted with a gas containing oxygen, the reaction temperature should be maintained at least 400 ° C or lower. In the temperature range of 300-400 ° C. where the selective catalytic reduction reaction occurs, Nitrogen oxides using impregnated carbon supports could be removed.

Example 1

A rotary vacuum dryer was used to impregnate the metal catalyst with the activated carbon in Reference Example 1 as a support.

Cobalt, copper, and iron were selected as the impregnating catalyst for removing nitrogen oxides, and the impregnating catalyst was Co (NO ₃ ) ₂ · 6H ₂ O, Cu (NO ₃ ) ₂ · 6H ₂ O, Fe (NO ₃₎ ) ₂ .6H ₂ O was used. In order to impregnate the carbon support with 1 ~ 10wt% of the metal catalyst, add 0.5 ~ 5.26wt% of the metal catalyst to the rotary vacuum dryer and add 47.37 ~ 49.75wt% of water to make the aqueous solution, and then add 47.37 ~ 49.75wt% of the carbon support. Inject.

For example, in order to make a carbon support containing 1wt% cobalt was carried out in the following manner. In order to make a 1wt% aqueous solution of cobalt, 99g of water was added to 4.9g of hydrated cobalt salt [Co 1g, (NO ₃ ) ₂ 2.1g, 6H ₂ O 1.8g]. Here, the molecular weight of Co is 59, (NO ₃ ) ₂ is 124, and 6H ₂ O is 108, so the hydrated cobalt salt (total molecular weight) was calculated as 291, and the hydrate contained in the cobalt salt was added to the amount of water to be injected. Did not consider The prepared aqueous solution was injected into a rotary vacuum dryer and then injected with 99 g of western barco activated carbon, which is a carbon support.

In the above calculation method, as the metal catalyst uses salt in the aqueous solution state, the metal catalyst injection amount is preferably calculated only for the catalyst. Therefore, the sample injection amount is 1 g of cobalt, 99 g of water, and 99 g of activated carbon, and when it is recalculated to 100 wt%, cobalt, water, and activated carbon can be calculated as 0.5, 49.75, and 49.75 wt%. In addition, to make a carbon support containing 10wt% cobalt, cobalt, water, and activated carbon were injected at 5.26, 47.37, and 47.37wt%.

When impregnating a metal using a rotary vacuum dryer, the expected parameters are the rate of evaporation of the impregnated aqueous solution, which is determined by the rotational speed (rpm), vacuum degree and heating temperature of the dryer. Among them, the heating temperature was fixed by referring to 65 ℃ which was determined as the most optimal temperature when impregnated metal salts with expanded graphite, which is a kind of carbon, and impregnated by changing the rotational speed and vacuum degree. 1-10 wt% of the catalyst was impregnated.

1. According to the speed of rotary vacuum dryer Impregnation Result

In order to select the impregnation conditions of the sample according to the rotational speed, the impregnation experiment was performed by fixing the pressure at -650mmHg and changing the rotational speed to 40, 60, 80, 100 rpm. The reason for setting the rotational speed as a variable is that non-uniform impregnation occurs due to the centrifugal force when the rotational speed is too fast, and nonuniform impregnation occurs even when the rotational speed is too slow.

Table 3 shows the specific surface area and pore volume of the metal catalyst impregnated activated carbon according to the impregnation rate. It has the smallest specific surface area and pore volume at rotation speed 60. This indicates that the rotational speed of 60 has the highest dispersibility than that of the rotational speeds of 40, 80, and 100. That is, the metal catalyst is impregnated in the pores of activated carbon, so that the specific surface area of the activated carbon is lowered as the amount of the metal catalyst is increased. Therefore, at low rotational speeds, as in this experiment, the rotation speed is slow, so that the sample cannot be mixed evenly, and the lower part is relatively impregnated, so it is highly likely that partial impregnation will occur. In addition, since the time of contact with the metal impregnation solution is reduced by the rapid rotation, the amount of evaporation is larger than the amount of impregnation, which is not suitable as a condition for impregnation. Therefore, 60 rpm was obtained at the optimum rotation speed for this experiment.

Table 3: Specific surface area of metal impregnated samples according to rotation speed

          RPM characteristics 40 60 80 100 Specific surface area 977.0m ² / g 924.6m ² / g 932.7m ² / g 970.8m ² / g Pore volume 0.74 cc / g 0.73 cc / g 0.73 cc / g 0.74 cc / g

2. About the pressure of the rotary vacuum dryer Impregnation Result

The impregnation experiment was performed by changing the vacuum pressure to 630, 650, 670, and 690mmHg based on the rotational speed of 60 rpm determined to be optimal according to the analysis result of the impregnation sample according to the rotational speed. After the experiment, SEM analysis was conducted to investigate the dispersion of metal components on the surface of the sample and the structural characteristics of the catalyst after metal impregnation. The change in vacuum pressure under impregnation conditions means the rate of evaporation of the solvent, water, in the solution on the bed. If the vacuum pressure is higher than the optimum state, the solvent is evaporated at a moment, and the dispersion degree is lowered. If the vacuum pressure is low, the impregnation time becomes longer, which causes the manufacturing cost increase due to energy loss.

Figure 3 shows an enlarged 10,000 times the metal impregnated activated carbon obtained by varying the pressure. Comparing the pictures when the pressure is 630mmHg and the pressure is reduced to 650mmHg, at 630mmHg the cross section of sharp and coarse unimpregnated activated carbon is mixed, whereas at 650mmHg, the metal components are impregnated onto the surface of activated carbon appropriately to produce a smooth and wide cross section. Appearing. Meanwhile, in the case of 670 and 690 mmHg, as the metal impregnation solution evaporates rapidly, the solution is first evaporated before the impregnation is carried out over the entire activated carbon, and thus partial impregnation occurs. Therefore, the pressure of 650mmHg was obtained at the rotational speed of 60 rpm as the optimal condition for this experiment.

Example  2

A nitrogen oxide removal experiment using the metal catalyst-impregnated activated carbon prepared by the above method was performed using the experimental apparatus as shown in FIG. 4.

The experimental apparatus can be divided into three parts such as gas injection unit, fixed bed reactor, and analysis unit. The gas inlet is supplied from the gas tank into which the nitrogen monoxide / nitrogen mixed gas, oxygen, nitrogen, and air are injected into the gas tanks 1a, 1b, 1c, and 1d, and the two-ball ball valves 2a, 2b, 2c, and 2d are used. Through the check valve (4a, 4b, 4c, 4d) to prevent the back flow of the gas after adjusting the flow rate using the gas flow rate (3a, 3b, 3c, 3d) and then to the gas mixer (5) Is injected. The injected gas passes through a fixed bed reaction system consisting of a furnace 7, a reactor 8 and a thermostat 9. Finally, after adjusting the amount of the exhaust gas and the analytical gas in the three-prong valve 10, the product passes through the dehumidifier 11 and then analyzes the concentration of the product in the gas analyzer 12.

At this time, the fixed bed reactor is located inside a tubular heating furnace capable of heating up to 1200 ° C, and used a quartz tube having an inner diameter of 27.6 mm and an outer diameter of 30 mm. Nitrogen oxide reduced in the fixed bed was injected into a NDIR (Non-dispersive Infrared) analyzer (Fuji Co. Japan) to analyze the product continuously.

The packing density of activated carbon impregnated by the experimental method was 0.36 g / ml, and was filled at a ratio of about 0.5 by the height / diameter ratio of the quartz tube reactor, and when it was filled at this ratio, the weight of the activated carbon was 1.08 g. Nitrogen monoxide used was 477 ppm, the remainder was standard gas mixed with nitrogen and injected at a volume flow rate of 350 cc / min. This flow rate is converted into Gas Hourly Space Velocity (GHSV) as follows.

GHSV = u _o / V = 350 [cc / min] / 2.99 [cc] = 7,023 h ^-1 (6)

The experimental sequence is as follows.

① Charging and setting of the sample: 1.08 g of metal impregnated activated carbon sample was charged to the quartz reactor, and then the whole system was set up.

② Pretreatment: In order to desorb carbon dioxide and oxygen impregnated in activated carbon exposed to air, nitrogen (99.9%) was used for 2 hours at a flow rate of 350 cc / min. At this time, the reactor temperature was maintained at 550 ° C. so that desorption was more likely to occur.

③ Constant temperature process: After 2 hours of pretreatment was completed, the system was heated to the temperature to be tested in nitrogen atmosphere and maintained for 30 minutes.

④ Nitrogen oxide removal test: When the conditions were to be tested, the nitrogen gas flowed for pretreatment was locked, and nitrogen oxide removal experiment was performed by flowing a standard gas containing 477 ppm of nitrogen monoxide at a flow rate of 350 cc / min.

1. Metal catalyst Impregnation  Nitrogen oxide removal experiment of anoxic using activated carbon

Using a carbon support impregnated with 7 wt% of cobalt in Western Baco activated carbon, 477 ppm of nitrogen monoxide and the rest were injected with only a standard gas consisting of nitrogen, and the nitrogen monoxide removal rate was examined for 2 hours.

Looking at all the graphs, the boundaries are divided into areas A and B. Area A is the area measured from the time of injecting nitrogen to the nitrogen monoxide until the inflection point of the measured concentration curve occurs. It shows the area up to the point where the change of concentration of nitrogen monoxide in the gas disappears. The initial nitrogen monoxide concentration of 0 ppm was not due to the removal of nitrogen monoxide, but because the nitrogen monoxide was analyzed during the pretreatment with 99.9% nitrogen. Each plot consists of a plot of the nitrogen monoxide concentration (ppm) that is analyzed in real time and the nitrogen monoxide conversion rate. Nitrogen monoxide conversion was calculated using the following formula based on the injected 477 ppm.

% Conversion (NO) = (477 ppm-NO concentration emitted) x 100/477 ppm (7)

It can be seen that even in the temperature range of 300 ° C., when the cobalt is impregnated with 7% or more, the conversion rate of nitrogen monoxide removal is already over 50%. Nitrogen monoxide conversion of 1 wt% impregnated cobalt samples was about 1%, 19% for 3 wt% impregnated samples, 21% for 5 wt% impregnated samples, 47% for 7 wt% impregnated samples and 54% for 10 wt% impregnated samples. Nitrogen monoxide conversion of was obtained. Nitrogen monoxide removal conversion according to cobalt impregnation rate at 350 ° C shows 4%, 34%, 39%, 59%, 58% when 1wt%, 3wt%, 5wt%, 7wt%, 10wt% impregnation Cobalt-impregnated activated carbon of more than% shows the highest conversion of nitrogen monoxide.

As a result of nitrogen oxide removal experiment at 400 ℃, the trend similar to that of the nitrogen monoxide concentration removal curve was tested. The best performance was also impregnated with 7wt% and 10wt%. The nitrogen monoxide removal conversion at this temperature was 79% and the nitrogen monoxide removal conversion for the 1wt% impregnated sample was 9%. In 450 ℃ it can be seen that better performance than when tested at 400 ℃. When 1%, 3%, 5%, 7%, 10% cobalt is impregnated, the NOx removal conversion is 11%, 61%, 72%, 95%, 97%.

At 500 ° C, the nitrogen oxide removal conversion was 15%, 75%, 83%, 99%, 100% when 1%, 3%, 5%, 7%, 10% cobalt was impregnated. As described above, activated carbon impregnated with cobalt of 7 wt% or more shows a conversion rate of 95% or more at 450 ° C. or higher.

2. Metal catalyst Impregnation  Nitrogen oxide removal experiment of activated carbon using aerobic

Nitrogen monoxide removal experiment was performed using simulated gas similar to the actual combustion flue gas with aerobic simulation gas (477ppm NO and 4% oxygen and the rest nitrogen). In the experiment, the impregnation rate was fixed to 7wt%, and through thermogravimetric analysis, the activated carbon as a support was burned at 450 ° C. or higher when the oxygen was 21%. Therefore, the experiment was limited to 300, 350, and 400 ° C.

6 shows a result of removing NO in the ranges of 300, 350, and 400 ° C. using a sample in which Western barco activated carbon was impregnated with 7 wt% of cobalt. As a result, the nitrogen monoxide removal conversion was 58%, which was 11% higher than the oxygen free atmosphere under the same conditions. The conversion at 350 ° C. was 68% and at 400 ° C. a conversion of 67%.

3. Metal catalyst Impregnation  Long-term test to remove nitrogen oxides from activated carbon using aerobic

7% of cobalt was impregnated with Western Baco activated carbon, and a result of performing a nitrogen monoxide removal experiment for 4200 minutes (70 hours) at 350 ° C., which is an operating range of a selective catalytic reduction process, is shown in FIG. 7. In the figure, the nitrogen monoxide emissions gradually increased up to 900 minutes, and then maintained 170 ppm of steady state for 70 hours. This is equivalent to 63% when converted to nitrogen oxide removal conversion, it can be seen that the nitrogen oxide removal rate is maintained more than 50% by long-term reaction. In the figure, the reason why the concentration of nitrogen monoxide increases and then changes to the steady state at about 1000 minutes is reached due to the difference in the desorption reaction rate of the product after the adsorption reaction of NO.

As air environment regulations are gradually tightened, it is necessary to secure air pollution treatment technologies that can cope with them. In order to apply to various pollutant sources, in addition to improving performance of existing treatment technologies, technologies to complement existing technologies should be developed.

The technology using the metal catalyst-impregnated carbon support developed in the present invention can remove nitrogen oxide with a simple device without the need for a reducing agent, and thus can be utilized as an auxiliary process of the currently commercially available selective catalyst reduction process. The present invention has a very high utility in a small factory due to its simple apparatus and operation, and furthermore, it can be utilized as an auxiliary process of a large process. In addition, this process can be applied to other flue gas and harmful gas treatment technology in addition to nitrogen oxides, the technical ripple effect of the present invention is very high. In other words, if the pressure increases to small and medium-sized enterprises with small factories in accordance with the strengthening of environmental regulations in the future, it is possible to flexibly cope with environmental regulations if it is applied after adding and adding a complex function for removing pollutants by expanding and supplementing the simple process developed in the present invention. There will be.

Claims (8)

47.37 ~ 49.75wt% of water was added to 0.5 ~ 5.26wt% of the metal catalyst to prepare an aqueous solution. After adding 47.37 ~ 49.75wt% of carbon support to the aqueous solution, the impregnation temperature was set at 25 ° C. to 90 ° C., and the impregnation rate was 40 A method for producing a reaction medium for removing nitrogen oxides comprising a metal catalyst impregnated on a carbon support, comprising: performing an impregnation in a rotary vacuum dryer at an rpm of 100 rpm and an impregnation pressure in a range of 500 mmHg to 700 mmHg. The method of claim 1, wherein the carbon support impregnated carbon support is based on a carbon component in activated carbon, activated carbon fiber, coke, charcoal, expanded graphite, which is a material mainly having a carbon component by thermal decomposition (carbonization) of organic materials. Method for producing a reaction medium for removing nitrogen oxides, characterized in that any one selected. According to claim 2, Nitrogen characterized in that to improve the porosity and surface modification of the carbon support by further including an activation process in order to increase the reactivity according to the increase in the contact area of the carbon support for the metal catalyst impregnation with nitrogen oxides Method for preparing a reaction medium for removing oxides. The nitrogen oxide removal according to claim 1, wherein the metal catalyst impregnated in the carbon support is any one selected from copper, cobalt, iron, nickel, platinum, rhodium, silver, chromium, cerium, palladium, vanadium, and ruthenium. Method for producing a reaction medium for. The method of claim 4, wherein the metal catalyst impregnated in the carbon support is any one selected from a combination of two or more catalysts. The method of claim 1, wherein the content of the metal catalyst impregnated in the carbon support is 1 to 10 wt% based on the weight of the reaction medium to be produced. A method for removing nitrogen oxides in an oxygen-free gas using a reaction medium prepared by the method for producing a reaction medium according to claim 1, In a reaction medium containing a metal catalyst impregnated carbon support, The injection flow rate of the flue gas is set from 10,000 hr ^-1 to 30,000 hr ^{- 1} , Operating temperature within 450 ℃ Nitrogen oxide removal method characterized in that the removal of nitrogen oxides. A method for removing nitrogen oxides in a combustion exhaust gas with oxygen using a reaction medium prepared by the method for producing a reaction medium according to claim 1, In a reaction medium containing a metal catalyst impregnated carbon support, Oxygen flow rate is set at 1vol% to 10vol%, The injection flow rate of the flue gas is set from 10,000 hr ^-1 to 30,000 hr ^{- 1} , Operating temperature in the range of 300 ℃ to 400 ℃ Nitrogen oxide removal method characterized in that the removal of nitrogen oxides.

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