KR100892381B1 - Method for regeneration of activity of spent activated carbon catalyst - Google Patents

Abstract

A regeneration method for activity of spent activated carbon catalysts is provided to offer regeneration activated charcoal having a NO conversion rate and a high removal rate of boron economically while preventing environmental contamination. A regeneration method for activity of spent activated carbon catalysts includes the following steps of: putting boron-adsorbed spent activated carbon in an aqueous solution including a surfactant; extracting boron by reacting the boron-adsorbed spent activated carbon and the aqueous solution; drying the boron-extracted spent activated carbon in 90°C ~ 150°C for 1 ~ 4 hours; and plasticizing the dried activated carbon in 400°C ~ 550°C for 1 ~ 4 hours. The surfactant is an antifoaming agent.

Description

Activation and Regeneration Method of Waste Activated Carbon Catalyst {METHOD FOR REGENERATION OF ACTIVITY OF SPENT ACTIVATED CARBON CATALYST}

The present invention relates to a method for activating and regenerating a waste activated carbon catalyst used for removing nitrogen oxides (NO _x ) in waste gas containing boron discharged from an LCD manufacturing process and the like, and more particularly, an activated carbon system reduced by boron deposition. The present invention relates to a method for activating and regenerating a waste activated carbon catalyst for improving the nitrogen oxide reduction performance of the catalyst.

Nitrogen oxides (NO _x ), along with sulfur oxides (SO _x ), are not only a major cause of acid rain, but also major air pollutants that cause photochemical smog. At present, as a technique for removing NO _x contained in flue gas generated from a stationary source such as a power plant and an incinerator, a selective catalytic reduction (SCR) using a catalyst is known to be the best in terms of technology and economics. The most important aspect of the SCR technology is the performance of the catalyst used here, and it is known that 30 to 40% of the SCR process investment is the catalyst price. SCR technology using a catalyst is a very efficient technology for removing NO _x with N ₂ , but there is a problem in reducing the conversion of NO _x due to wear, exchange and toxicity of the catalyst. In particular, activated carbon-based SCR catalysts used to remove nitrogen oxides (NO _x ) in boron-containing waste gas discharged from LCD manufacturing processes, etc., are inactivated due to the deposition of boron to block pores in the catalyst or to cover active sites. Due to this there is a problem that the life is very short.

In this regard, U. S. Patent No. 6,395, 665 discloses a method for cleaning a catalyst with a cleaning solution containing sulfuric acid (H ₂ SO ₄ ) or an aqueous ammonia solution for regeneration of SCR spent catalyst poisoned with heavy metal (As). U.S. Patent No. 4,615,991 discloses a method of washing with an aqueous oxalic acid solution and then impregnating the tungsten (W) component for cleaning and regeneration of the SCR spent catalyst. Korean Patent No. 626925 discloses a method of cleaning and recycling such a waste catalyst by using an anionic surfactant, a nonionic surfactant, a metal compound, or the like as a surface active material. Korean Patent No. 668926 is a honeycomb type SCR waste catalyst that is contaminated by alkali metals, alkaline earth metals, heavy metals, etc., and has greatly removed nitrogen oxides. A method for regenerating an SCR spent catalyst is disclosed. Korean Laid-Open Patent Publication No. 2008-24925 discloses a regeneration method comprising immersing a waste denitrification catalyst in distilled water and washing by oscillating ultrasonic waves.

Conventional techniques for regenerating a waste denitrification catalyst whose catalytic activity is deteriorated due to such deactivation factors are methods of restoring catalytic performance through a chemical method of removing poisonous substances deposited on the surface of the catalyst using an acid or alkaline solution. It is about. However, due to the bubbles contained in the pores of the activated carbon catalyst having a very small pore size, it is difficult to penetrate the cleaning liquid into the pores, and thus there is a disadvantage in that the washing is not performed well. In addition, in order to remove various poisoning substances, various cleaning components should be used, and after cleaning, problems with the disposal of the waste solution occur.

Accordingly, the present invention is to solve the problems of the prior art as described above, the boron-adsorbed activated carbon in an aqueous solution containing a surfactant, preferably an antifoaming agent and a temperature of 60 to 90 ℃ and pressure of 10 to 50 torr Under reaction for 30 to 60 minutes to extract boron; Drying the boron-free activated carbon in air at 90 to 150 ° C. for 1 to 4 hours; And calcining the dried activated carbon at a temperature of 400 to 550 ° C. for 1 to 4 hours under a nitrogen atmosphere.

The present invention not only provides an economical method for activating and regenerating waste activated carbon catalysts while preventing environmental pollution by using water instead of an organic solvent as a solvent, but also includes a surfactant, in particular an antifoaming agent, thereby having a high boron removal rate and a NO conversion rate. To provide activated carbon.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for activated regeneration of a waste activated carbon catalyst comprising the step of extracting boron by reacting boron-adsorbed activated carbon in an aqueous solution containing a surfactant.

In particular, the present invention is the step of extracting boron by reacting the boron-adsorbed activated carbon in an aqueous solution containing a surfactant, preferably an antifoaming agent for 30 to 60 minutes at a temperature of 60 to 90 ℃ and a pressure of 10 to 50 torr It relates to an activated regeneration method of the waste activated carbon catalyst comprising a.

In addition, the present invention includes the step of drying the boron-removed activated carbon in air of 90 to 150 ℃ for 1 to 4 hours.

In addition, the present invention includes the step of firing the dried activated carbon for 1 to 4 hours at a temperature of 400 to 550 ℃ under a nitrogen atmosphere.

The present invention may comprise a surfactant at 0.1 to 1% by weight, preferably 0.5 to 0.8% by weight, most preferably 0.5% by weight based on the total weight of the aqueous solution. As said surfactant, an antifoamer is preferable. If the amount of the surfactant is less than 0.1% by weight, the surface tension is large, so that desorption of boron from the waste activated carbon is difficult. If the content is more than 1% by weight, the amount of the antifoaming agent is increased, although it is not preferable.

1 shows the surface tension per weight of the waste activated carbon. Surface tension is a criterion that indicates the strength of waste activated carbon adsorbing boron. The small surface tension means that boron can be easily desorbed.

Surfactants reduce the surface tension of water to 30 mN / m or less. When the concentration of the surfactant is increased to some extent in the aqueous solution, the surfactant, which was in a simple dispersed state, forms an aggregate (micelle). The concentration at this time is called the critical micelle concentration (abbreviated CMC), and even more surfactants do not decrease the surface tension. Therefore, it can be said that it is most effective to measure the CMC whose surface tension is no longer reduced while increasing the concentration of the surfactant, and injecting the surfactant by the CMC concentration.

In this invention, the temperature of aqueous solution is 60-90 degreeC, Preferably it is 70-90 degreeC, Most preferably, it is 70-80 degreeC. If the temperature of the aqueous solution is less than 60 ℃ reduced the NO _x conversion of the treated activated carbon is not preferable, and if it exceeds 90 ℃ the removal rate of boron and NO _x conversion relative to the energy consumption is not preferred.

In addition, the boron extraction step according to the invention is preferably carried out for 30 to 60 minutes. If the extraction time is less than 30 minutes, incomplete extraction of boron is achieved, and if it exceeds 60 minutes, the mechanical strength of the waste activated carbon is lowered, which is not preferable.

2 is a graph showing the NO _x conversion rate for each temperature. The removal rate of boron and NO _x conversion in water of 70 to 90 ℃ increases, and looking at the solubility curve of boron it can be seen that the solubility of boron increases with increasing temperature.

In addition, the present invention is preferably carried out under vacuum, in particular under pressure conditions of 10 to 50 torr. In addition, when the relationship between the pressure conditions and boron desorption is examined through experiments, the pressure conditions of 10 to 30 torr are most preferable in terms of boron removal rate and NO _x conversion rate. If the pressure is less than 10 torr, the efficiency of energy use is lowered. If the pressure is more than 50 torr, the boron desorption efficiency in the vacuum is lowered, which is not preferable.

When vacuum is applied to the aqueous solution containing waste activated carbon, it can be seen that bubbles are generated in pores in the waste activated carbon, which means that boron is being desorbed in a vacuum state. Such pressure conditions are preferably maintained for 10 to 30 minutes. If the pressure condition is less than 10 minutes, it is difficult to induce sufficient desorption of boron, and if it exceeds 30 minutes, the desorption efficiency does not increase compared to the input of energy, which is not preferable.

The present invention may further comprise the step of drying the waste activated carbon from which boron is extracted. The drying step is preferably performed for 1 to 4 hours in the air of 90 to 150 ℃.

The present invention may further comprise calcining the waste activated carbon. The firing step is preferably carried out for 1 to 4 hours at a temperature of 400 to 550 ℃ the dried activated carbon under a nitrogen atmosphere.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example  1 (activated carbon analysis)

The metal constituents of fresh activated carbon and waste activated carbon were analyzed, and the specific surface area and NO conversion were measured. As shown in Table 1, it can be seen that the boron component of the waste activated carbon is very high, and the specific surface area is very low. NO _X conversion also shows similar performances for new and regenerated activated carbon, whereas spent activated carbon shows very low activity.

Example  2( Atmospheric pressure  Treatment experiment)

The oil bath was filled with silicone oil and heated to 60 ° C. After putting 20 g of waste activated carbon and 300 ml of distilled water into a round flask, a thin layer of grease was applied to the round flask and the entrance of the rotary evaporator, and the round flask was mounted on the rotary concentrator. The chiller was operated to circulate the coolant, the round flask was immersed in an oil bath, and the rpm was set to 22 rpm. After a certain period of time, activated carbon was filtered out of the solution and stored separately. Activated charcoal was dried at 100 ° C. for 10 hours and then stored in a desiccator, and some of the activated carbon was further calcined in air at 400 ° C. and stored in a desiccator.

The experiment was repeated by raising the temperature at 10 ° C. intervals and the concentration of boron, NO conversion and specific surface area were investigated. As shown in Table 2 below, the regenerated activated carbon treated at a temperature of 90 ° C. showed very high activity compared to other temperatures, and showed about 73% of the activity of the new activated carbon. The waste activated carbon showed a remarkable increase in activity compared to 8.7%. In particular, the specific surface area increased with the additional firing, compared with drying only.

Meanwhile, in order to determine the effect of the reaction time on the activity of the regenerated activated carbon, various reaction times were applied in hot water at 70 ° C. to remove boron, and the activated carbon was regenerated through the same drying and firing steps as in Example 1. As shown in Table 3 below, it can be seen that the specific surface area and activity are the best when treated for 60 minutes.

Example  2 (vacuum treatment experiment)

An aspirator was installed in the rotary concentrator, and the oil bath was filled with silicone oil and heated to 70 ° C. After putting 20 g of waste activated carbon and 300 ml of distilled water into a round flask, a round flask was mounted in the rotary concentrator and a chiller was operated to circulate cooling water. The aspirator installed in the rotary concentrator was operated to apply a vacuum of about 30 torr and maintained for about 10 minutes. The round flask was then immersed in an oil bath and operated at 22 rpm. Thereafter, activated carbon and a solution were treated in the same manner as in Example 1.

Table 4 below shows the vacuum treatment effect upon activated carbon regeneration. After the vacuum of about 30 torr was maintained for about 10 minutes, bubbles were not observed, and the atmospheric pressure reaction was performed. As a result, boron removal rate and NO conversion were increased.

Example  3 (surfactant treatment experiment)

Defoamer and dispersant were used as surfactant. FC-250S (GE Chem Co., Ltd.) was used as an antifoaming agent, and SN-DISPERSANT 44S (Sanoff Korea Co., Ltd.) was used as a dispersant.

The surface tension lowering effect by the addition of surfactant was measured using the most widely known Du Nouy ring method. The ring method uses a platinum ring, which is placed on the surface of the water slightly and pulled up slowly, then the water rises with the ring until the force pulled from the bottom and the force pulled from the top are equal. When the water pulled up and the ring pulled weaker as compared to the following, the water fell from the ring and the surface tension was calculated by measuring the force at this time.

Table 5 shows the surface tension per surfactant weight based on 100 ml of distilled water. As the amount of the antifoaming agent and the dispersant increases, the surface tension decreases, and it can be seen that the surface tension lowering effect of the antifoaming agent is much greater than that of the dispersant. CMC of the antifoaming agent used in this experiment was measured at 0.5% by weight.

In Table 6, after removing boron adsorbed to the waste activated carbon at 90 ℃, when the waste activated carbon is regenerated through the drying and calcining step in the same manner as in Example 1, the effect of the surfactant on the activated carbon regeneration. When the antifoaming agent (FC-250S) was used, the removal rate of boron was 82.6%, which was higher than that of no surfactant, and the NO conversion was also increased to 44.6%.

The effects of the firing conditions are shown in Table 7 below. As shown in Table 7, the regenerated activated carbon subjected to nitrogen treatment at 550 ° C. for 2 hours showed the highest activity, and the NO conversion was also excellent.

The boron content of the regenerated activated carbon was analyzed by ICP, and the elements of the regenerated activated carbon, which had been dried and calcined, were dissolved by using a super acid solution and analyzed by ICP. The specific surface area of the regenerated activated carbon was measured using a Micromeritics ASAP 2010. Specifically, the activated carbon sample was dried, 0.3 g of the sample was mounted, heat treated or pretreated at 250 ° C. and vacuum for 5 hours, and then nitrogen was flown at 77 K to measure the specific surface area. One-point surface area was measured in a continuous flow using a Bell Cat device from Bell Japan. On the other hand, the physical strength of the activated carbon was measured using UTM (Hounsfield, H25KS).

1 is a graph showing the change of the surface tension according to the concentration of the surfactant.

2 is a graph showing the NO conversion of regenerated activated carbon at a specific temperature of the aqueous solution.

Claims (9)

In the activated regeneration method of the waste activated carbon catalyst, A method of activating and regenerating a waste activated carbon catalyst, comprising: extracting boron by reacting boron-adsorbed waste activated carbon in an aqueous solution containing a surfactant. The method of claim 1, The method of claim 1 further comprising the step of drying the boron-derived waste activated carbon in air at 90 to 150 ℃ for 1 to 4 hours. The method of claim 2, And calcining the dried activated carbon at a temperature of 400 to 550 ° C. for 1 to 4 hours under a nitrogen atmosphere. The method according to any one of claims 1 to 3, And the surfactant is 0.1 to 1% by weight based on the total weight of the aqueous solution. The method according to any one of claims 1 to 3, And said surfactant is an antifoaming agent. The method according to any one of claims 1 to 3, The activated regeneration method of the waste activated carbon catalyst, characterized in that the temperature of the aqueous solution is 60 to 90 ℃. The method according to any one of claims 1 to 3, The regeneration process of the activated activated carbon catalyst, characterized in that the extraction step is carried out for 30 to 60 minutes. The method according to any one of claims 1 to 3, Wherein said extraction step is performed under a pressure condition of 10 to 50 torr. The method of claim 8, And the pressure condition is applied for 10 to 30 minutes.

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