KR20080027614A - A method for regenerating catalysts - Google Patents

Abstract

A catalyst regenerating method carried out regardless of types of reactors or catalysts is provided, a very strong catalyst regenerating method accomplished by a regenerating apparatus designed simply and fabricated very economically is provided, an environmentally friendly catalyst regenerating method capable of minimizing release of harmful substances is provided. In a method for regenerating non-precious metal catalysts or precious metal catalysts, and solid acid catalysts of which activities are deteriorated by coke deposition, a catalyst regenerating method comprises the step of burning coke using oxidizing power of NO2. The catalyst regenerating method further comprises the step of injecting NO and air into an oxidation catalyst region disposed on a front part or a rear part of a catalyst region to be regenerated to generate NO2. The oxidation catalyst region is formed of a catalyst comprising platinum group metals. The catalyst regenerating method further comprises the step of refluxing NO produced from the catalyst to be regenerated as a by-product.

Description

A method for regenerating catalysts

1A and 1B show schematic diagrams of a catalyst regeneration method using conventional air and a catalyst regeneration method according to the present invention, respectively.

2 is a regeneration of Cu / Al ₂ O ₃ by the conventional method shown in Figure 1a Obtained CO ₂ and CO concentration profiles,

Figure 3 shows the temperature and CO ₂ (CO) profile when regenerating the Cu / Al ₂ O ₃ catalyst using the NO ₂ oxidation power according to the present invention,

4 and 5 illustrate profiles of the regeneration method using air and the regeneration method using NO ₂ for the precious metal catalyst Pt / Al ₂ O ₃ to be regenerated, respectively.

FIG. 6 illustrates a profile obtained by heating at 600 ° C. after maintaining 350 ° C. for a Pt / Al ₂ O ₃ catalyst.

FIG. 7 shows profiles of temperatures and CO ₂ when the zeolite catalysts to be regenerated are regenerated by air and NO ₂ , respectively.

TECHNICAL FIELD The present invention relates to a method for regenerating a catalyst, and to a useful method for regenerating a chemical catalyst having a need for regeneration in which the active point is closed by coke and the surface area is reduced.

In the production of petrochemical and synthetic raw materials, the feed stream of raw materials passes through catalysts in the reactor to produce the necessary products or to remove impurities. The catalytic state is important for this operation because the economic operation of the reactor and the plant is greatly influenced by the catalyst state. Product conversion, quantity or operating temperature depends on catalyst activity.

Catalytic activity decreases over time due to factors such as the presence of impurities, the concentration of impurities in the feed stream, the types of by-products from side reactions, and the reactor operating time. For example, on the surface of a catalyst such as Pt / Al ₂ O ₃ catalyst used for dehydrogenation reaction or Cu / Al ₂ O ₃ used for selective hydrogenation reaction, coke may be attached to the reaction by polymerization of raw materials. The surface area that can be reduced. In the case of solid acid catalysts such as zeolites, coke deposition is also the most representative cause of activity deterioration. This is accompanied by a decrease in product yield. Therefore, after operating the reactor for a predetermined period, the catalyst must be regenerated or replaced with a new catalyst.

There are various catalyst regeneration methods in the petrochemical raw material manufacturing field. Methods are known, such as using steam, removing coke by combustion, or using certain solvents.

However, the regeneration method by steam or air has various problems. First, since regeneration is performed at high temperature, there is a problem in that catalytic activity due to catalyst sintering is lowered. Thus, in order to prevent possible catalyst sintering, the combustion temperature is gradually increased and thus the regeneration period is prolonged. In addition, there is a risk of CO generation due to incomplete combustion, catalyst damage due to rapid exotherm, and the cost of maintaining a high temperature for a long time or an excessive cost additionally generated as the production is stopped.

In addition, the method of extracting the catalyst poisoning material using the solvent requires another regeneration process to remove the solvent from the catalyst and poses an environmental burden for treating the solvent.

The present invention is to solve the above problems, to propose a catalyst regeneration method that can be carried out irrespective of the type of reactor or catalyst.

The present invention also relates to a very powerful catalyst regeneration method which can be achieved by a regeneration device which is simple in design and very economical to manufacture. The present invention relates to an environmentally friendly catalyst regeneration method that can minimize the emission of harmful substances.

In order to achieve the above object, the present invention is characterized in that in the catalyst regeneration method, using the oxidation power of NO ₂ .

An object of the present invention can be achieved by a catalyst regeneration method comprising the step of injecting NO and air into the oxidation catalyst to produce NO ₂ .

In another aspect, the present invention can be achieved by a catalyst regeneration method comprising the step of injecting NO and air directly into the regeneration catalyst rather than the oxidation catalyst.

The present invention can also be accomplished by a catalyst regeneration method further comprising a method for removing residual NO _x and harmful gas components that may be generated after regeneration.

Other objects and features of the present invention will be described below with reference to the accompanying drawings, but these embodiments are for illustrative purposes only, of course, the present invention is not limited thereto. The basic idea of the present invention is to propose a method for regenerating while preserving the physical properties of the catalyst by burning catalyst inhibitors such as coke fused to the surface of the catalyst to be regenerated at low temperature by using the oxidizing power of NO ₂ .

1A and 1B show schematic diagrams of a catalyst regeneration method using conventional air and a catalyst regeneration method according to the present invention, respectively. 1 is specifically designed and tested for the Cu / Al ₂ O ₃ catalyst used in the selective hydration reaction.

According to the conventional catalyst regeneration method by air, the regeneration of the Cu / Al ₂ O ₃ catalyst is carried out at least 350 ℃, there is a risk of deactivation due to sintering, etc., but the regeneration method according to the present invention is NO The oxidation power of ₂ is used for coke combustion. To this end, specifically, when NO and air are introduced into the oxidation catalyst zone inlet and NO ₂ generated therefrom is added to Cu / Al ₂ O ₃ to be regenerated, the regeneration temperature is reduced to 250 ° C to 300 ° C. Can be obtained. More preferably, the NO which is released through the regeneration catalyst and the reaction with NO ₂ can be circulated for the purposes of the present invention.

The applicable oxidation catalysts can vary widely and use known Pt / Al ₂ O ₃ catalysts.

FIG. 2 is a CO ₂ and CO concentration profile obtained when regenerating a Cu / Al ₂ O ₃ catalyst by the conventional method shown in FIG. 1A. It can be seen from the concentration profile of CO ₂ that combustion starts around 300 ° C. It also shows two peaks around 350 ° C and around 450 ° C. If it is regenerated at 350 ℃, the coke burning near 450 ℃ can be difficult to regenerate. The air flow rate of FIG. 2 was performed at 100 ml / min and the temperature increase rate was set at 4 ° C./min.

In order to implement the present invention, the oxidation catalyst (Pt / Al ₂ O ₃ ) region is located in front of the Cu / Al ₂ O ₃ region, which is a regeneration object, and the following reaction formula is established by injecting NO and air into the oxidation catalyst inlet. .

Oxidation catalyst area

2NO₂ 2NO + O2

2NO ₂

Regeneration catalyst area

NO + CONO ₂ + C

NO + CO

NO + CO₂ NO ₂ + CO

NO + CO ₂

Total reaction

2NO + CO₂, 2NO ₂ + C

2NO + CO ₂ ,

At this time, since 2NO can be circulated to the oxidation catalyst zone, the same result can be obtained even if the oxidation catalyst zone is at the front end or the rear end of the regeneration catalyst zone.

Based on the above reaction scheme, FIG. 3 shows the temperature and CO ₂ (CO) profile when regenerating the Cu / Al ₂ O ₃ catalyst using the NO ₂ oxidation power according to the present invention. According to this, it can be seen that CO ₂ concentration change, that is, the coke combustion is started at least around 200 ℃, and the second peak seen near 450 ℃ in Figure 2 also disappeared. In addition, the concentration profile of the CO is CO ₂ that is generated It supports the reaction mechanism of the above formula. Figure 3 is a test condition of 4.66% NO / N 2 balance 20ml / min, air 80ml / min, temperature increase rate 4 ℃.

According to the above-described conception and the embodiment implementing the same, specifically by the catalyst regeneration method using the NO ₂ oxidizing power, injecting NO and air into the oxidizing catalyst, and to the coke combustion using the oxidizing power of NO ₂ generated therefrom By the catalyst regeneration method, the regeneration temperature is reduced, it is possible to maintain the catalytic activity by increasing the regeneration efficiency by burning to the coke that can not be regenerated at a low temperature, the regeneration period is shortened can be expected to increase the productivity, the injection NO concentration By controlling the reactor temperature can be adjusted to obtain an effect that can prevent the catalyst damage due to rapid heat generation.

The above example is for the non-noble metal catalyst Cu / Al ₂ O ₃ , the inventors further carried out the same experiment for the regeneration method Pt / Al ₂ O ₃ catalyst of the precious metal catalyst. Through this, the noble metal catalyst itself functions as an oxidation catalyst capable of oxidizing NO, and therefore, the purpose of the present invention was to determine whether or not an oxidation catalyst zone to be located in front of the catalyst to be regenerated.

For this purpose, the Pt / Al ₂ O ₃ catalyst used in the selective hydrogenation reaction was selected to prepare a profile under the same conditions as in the case of the Cu / Al ₂ O ₃ catalyst. 4 and 5 shows a modification showing a profile according to the reproducing method using a reproducing method, and NO ₂ with the respective air, this structure can see only the CO ₂ is detected in the reproducing method to 500 ℃ using air, but the NO ₂ In the regeneration method used, since CO ₂ is not detected around 400 ° C., the regeneration effect is excellent. Meanwhile, in order to verify the low temperature regeneration effect using the NO ₂ oxidation power, the profile of the Pt / Al ₂ O ₃ catalyst maintained at 350 ° C. and then elevated at 600 ° C. is shown in FIG. 6. According to this, it can be seen that most of the coke fused to the experimental object catalyst surface was burned and regenerated at 350 ° C.

The method for regenerating the catalyst using the NO ₂ oxidation power according to the present invention is not limited to the above Cu./Al ₂ O ₃ and Pt / Al ₂ O ₃ catalysts. The same experiment was performed for. FIG. 7 shows profiles of temperatures and CO ₂ when the zeolite catalysts to be regenerated are regenerated by air and NO ₂ , respectively. In the case of regeneration by air, combustion of carbon starts around 320 ° C, and the maximum concentration of CO ₂ is around 370 ° C. On the other hand, in the case of regeneration using the oxidizing power of NO ₂ , the combustion of carbon occurs in the range of 150 ° C. to 320 ° C., and the concentration of CO ₂ is considerably lowered even around 370 ° C. indicating the maximum concentration. In addition to the effect of lowering the regeneration temperature, this demonstrates the effect of avoiding catalyst damage due to the exotherm that can occur during the rapid combustion of carbon.

Table 1a shows the carbon content analysis results when regenerating the Cu / Al ₂ O ₃ catalyst using the NO ₂ oxidation power according to the invention, and Table 1b regenerating the Pt / Al ₂ O ₃ catalyst. It can be seen that the regeneration result of the present invention compared to the existing method is excellent at the same temperature, showing excellent regeneration performance over time even at a lower temperature.

Therefore, in the case of the noble metal catalyst that can act as an oxidation catalyst rather than the non-noble metal catalyst, an oxidation catalyst zone for generating NO ₂ is not required, but for the purpose of controlling the regeneration temperature and increasing the regeneration efficiency, etc. Of course, an oxidation catalyst zone may be installed.

As described above, the embodiments of the present invention have been described, but various modification possibilities cannot be excluded. Therefore, the idea of the present invention is to burn the coke, which is a catalyst surface fixation material, by utilizing NO ₂ oxidizing power uniquely and creatively as compared to the conventional technology related to catalyst regeneration using air, and to regenerate the oxidation catalyst zone for NO ₂ introduction. It should be noted that the NO generated in accordance with the present invention can be located at the front and rear of the zone and in the catalyst regeneration process, which can be used for recycling.

The present invention relates to, characterized by using the oxidizing power of the NO ₂ and, NO, and injecting air to the oxidation catalyst is not a catalyst regeneration method or catalytic oxidation of NO and air, comprising the step of generating the NO ₂ to the catalyst regeneration method It can be implemented by a catalyst regeneration method comprising the step of directly injecting the regeneration catalyst, thereby preventing catalyst sintering by the reduction of the regeneration temperature, by burning to the coke that can not be regenerated at low temperatures to increase the regeneration efficiency catalyst In addition to maintaining the activity, the present invention proposes a useful regeneration method that is very simple to manufacture and low in maintenance cost. It is also proposed an eco-friendly catalyst regeneration method that minimizes the emission of harmful gases by refluxing NO generated after coke combustion using NO ₂ to the oxidation catalyst housing and removing residual NO and harmful gases through SCR equipment after catalyst regeneration. .

Claims (4)

A method for regenerating a non-noble metal or a noble metal or solid acid catalyst whose activity has been reduced by coke deposition, the method comprising: combusting coke using an oxidizing power of NO ₂ . The method of claim 1, comprising injecting NO and air into an oxidation catalyst zone disposed either before or after the catalyst zone to be regenerated to produce NO ₂ . The method of claim 2, wherein the oxidation catalyst zone is made of a catalyst containing a platinum group metal. The method of claim 2 or 3, further comprising refluxing NO that is withdrawn from the catalyst to be regenerated.

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