KR100879707B1 - A molybdenum based catalyst?sorbent for concurrently removing h2s and nh3, the process for preparing the catalyst?sorbent, gas purifying system and gas purifying method using the catalyst?sorbent - Google Patents

Abstract

Relates to a method of removing the absorbent and H ₂ S and NH ₃ at the same time - the invention there H ₂ S and for the removal of NH ₃ at the same time, reproducible molybdenum-based high-efficiency catalyst with impurities under the reducing gas atmosphere such as coal gas Molybdenum catalyst-absorber according to the present invention, the H ₂ S absorption and NH ₃ decomposition components of Mo and Ni or oxides of Mo and Ni; And a support component of Al ₂ O ₃ and AlPO ₄ , and may be prepared by various methods such as impregnation, coprecipitation, sol-gel, and gel mixing. The molybdenum catalyst-absorber of the present invention is excellent in the simultaneous removal of H ₂ S and NH ₃ and has a fast regeneration ability. In addition, even after repeated removal of H ₂ S and NH ₃ several times, the ability to simultaneously remove H ₂ S and NH ₃ can be maintained without decreasing.

H₂S gas, NH₃ gas, simultaneous removal process, molybdenum catalyst-absorber

Description

MOLYBDENUM BASED CATALYST-SORBENT FOR CONCURRENTLY REMOVING H2S AND NH3, THE PROCESS FOR PREPARING THE CATALYST-SORBENT, GAS PURIFYING SYSTEM AND GAS PURIFYING METHOD USING THE CATALYST―SORBENT}

1 is a block diagram schematically illustrating a conventional coal gasification combined cycle power generation system.

FIG. 2 is a schematic block diagram of a coal gasification combined cycle power generation system including a simultaneous removal system of H ₂ S and NH _{3 according} to the present invention.

3 is a diagram illustrating NH ₃ and H ₂ S removal performances of MNA and MNAP according to Examples 1 and 3. FIG.

4 shows NH ₃ and H ₂ S removal performances of MNA and MNAP according to Examples 2 and 4. FIG.

* Explanation of symbols for the main parts of the drawings *

1, ... coal gasifier

2 ... dust collector filter to remove dust, etc.

3 ... Desulfurization system using desulfurization of metal oxides

4 ... desulfurization regeneration system

5 ... NH ₃ decomposition system

6 ... gas turbine

7 ... steam turbine

1 '... coal gasifier

2 '... dust collecting filter to remove dust, etc.

3 '... Simultaneous Removal of H ₂ S and NH ₃ Using Molybdenum Catalyst-absorbers

4 '... catalyst-absorbent regeneration system

5 '... gas turbine

6 '... Steam turbine

The present invention comprises an active ingredient containing Mo and Ni; And molybdenum-containing catalyst for removing, H ₂ S and NH _3, which includes a support to disperse the active ingredient at the same time - the impurity such, under a reducing gas atmosphere such as a coal gasification combined cycle (IGCC) process according to the absorber H ₂ The present invention relates to a catalyst-absorber capable of simultaneously removing S and NH ₃ in a temperature range of 580 to 700 ° C. in a single process, and regenerating in a temperature range of 600 to 750 ° C., and a method for preparing the same.

Coal Gasification Combined Cycle (IGCC) is a dust collecting and desulfurization unit in the gas refinery where coal gas generated when gas is reacted with oxygen at high temperature and high pressure (1200 ~ 1500 ℃, 20atm) in gasifier , Removes dust, sulfur and ammonia from coal gas by passing NH ₃ removal device, and combines gaseous turbine and steam turbine with H ₂ and CO gas It is used as a power generation fuel, and is mainly comprised by a coal gasification part, a gas refinery part, and a power generation part.

In general, impurities generated when gasifying coal are H ₂ S, NH ₃ , HCl, etc., and the concentration is H ₂ S: 5000-15000 ppm, NH ₃ : 200-5000 ppm, and the type of coal or gasifier Depending on the structure of the concentration appears different. (For example, Texaco-Gas: NH ₃ 1800-2000ppm, H ₂ S 14000ppm; U-Gas: NH ₃ <1000ppm, H ₂ S 5000ppm.) By the way, these gases are very corrosive gases with gas turbine and when the steam turbine and other equipment or apparatus is able to corrosion and emissions to the atmosphere H ₂ S is sO _X, NH ₃ will not only be converted into secondary pollutants, such as NO _X, these environmental point of view it may cause acid rain Is a serious problem in the country. Therefore, there is a need to remove these gases using an appropriate technique in the gas purification process of the IGCC process.

Among the fuel gases discharged from coal gasifiers, H ₂ S can be removed in _two ways: wet desulfurization and high temperature dry desulfurization under development. Currently, wet desulfurization is widely used in petrochemical plants. However, wet desulphurization has a high heat loss and high costs associated with the treatment of secondary contaminants generated during the wet process. For this reason, wet desulfurization has proved to be less economical in IGCC processes than high temperature dry desulfurization. On the other hand, the high-temperature dry desulfurization method selectively removes H ₂ S gas at a high temperature of about 500 ° C. or more using a desulfurization agent of various metal oxides, thereby preventing condensation of tar due to gas cooling, having low heat loss, and low temperature. It is known that the thermal efficiency is 3 to 4% higher than that of the wet desulfurization process. Accordingly, many research institutes at home and abroad are making great efforts to develop a desulfurization agent suitable for high-temperature and low-temperature dry desulfurization.

In this regard, various additives may be added to zinc-based desulfurization agents known from many documents, such as U.S. Pat.Nos. 4,449,11,525,454,5714431,6683024,6649043,6724533,6544410, In order to improve the desulfurization performance and the regeneration capacity of zinc-based desulfurization agents by varying the manufacturing method of desulfurization agents, studies have been conducted. The zinc-based desulfurization agent was developed in the high and medium temperature ranges and the desulfurization performance was excellent while maintaining long-term stability at about (16 g S) / (g absorbent). In addition, in order to develop a desulfurization agent suitable for fluidized bed reaction using organic and inorganic binders in Korea, researches to increase the wear resistance by 90% or more have been actively conducted. Succeeded in developing a desulfurizer suitable for fluidized bed reactions of more than%.

Meanwhile, another impurity, NH _3, is also an impurity to be removed, and there are physical removal methods and chemical removal methods. However, the physical removal method is not used well because the H ₂ S and CO ₂ reacts with NH ₃ to form a salt by removing in an aqueous solution. Among the chemical removal methods, the PHOSAM process is representative and is currently used in about 20 coal plants worldwide. This is a wet process consisting of an absorption tower and a regeneration tower, in which the absorption tower selectively absorbs and removes NH ₃ by the ammonium phosphate absorption solution, separates the absorbed NH ₃ and regenerates it into a dilute solution. It is a method of producing anhydrous ammonia as a liquid. However, this method has a high heat loss since the process is performed at a low temperature of 50 to 100 ° C. and is not suitable for the IGCC process. Therefore, efforts are being made to decompose NH ₃ in a high temperature region, and the HTSR-1 process as described in US Pat. No. 5,121,12198 has a ZnFe-based, FeCr-based, and Ni-based process at about 600-800 ° C. It is a process that decomposes NH ₃ using various catalysts and is evaluated as a more effective process in terms of thermal efficiency than PHOSAM process.

Recently, studies to remove H ₂ S and NH ₃ simultaneously to secure economic feasibility, but studies on a single process and a catalyst with simultaneous removal of H ₂ S and NH ₃ are still insufficient. For example, US Pat. No. 5,881,11 adds molybdenum-based additives to zinc titanium-based desulfurization agents to remove H ₂ S and NH ₃ at about 530 ° C. simultaneously, but the desulfurization agent must be activated with H ₂ S for 1 hour. In the gas composition including H ₂ , the NH ₃ removal rate was 16%, and in the gas composition in which H ₂ S was present, the low ammonia removal rate was 36%. United States Patent No. In the 4,374,105 arc showed a 62% decomposition rate of NH ₃ at a high temperature of 760 ℃ using a ZnO desulfurizing agent, in the condition that the H ₂ S and NH ₃ present at the same time under the conditions of about 600 ℃ with 150psi of NH ₃ The removal rate was 58% and the removal rate of H ₂ S was about 99%. In addition, U.S. Patent No. 4,192,854 discloses a wet removal method, using a CuSO ₄ to remove the H ₂ S and by the sulfuric acid is reacted with NH ₃ generated as a by-product being generated ammonium sulfate using the method of removing the NH ₃ However, as H ₂ S and NH ₃ are removed in a wet manner, the removal efficiency is superior to 90% or more, but the thermal efficiency of the IGCC process is reduced because it is performed at a low temperature. In addition, U. S. Patent No. 5440873 uses a PSA (Pressure Swing Absorption) system as part of simultaneous removal of H ₂ S and NH ₃ , which is characterized by the fact that H ₂ S and Although the removal efficiency of NH ₃ represents a maximum of 95%, there is a problem that a very high pressure is required and a device for separating H ₂ S and NH ₃ is required.

As described above, studies to simultaneously remove H ₂ S and NH ₃ have been conducted, but as can be seen from the results, a catalyst having a function of simultaneously removing 90% or more of H ₂ S and NH ₃ at a high temperature Absorbents have not yet been reported.

Accordingly, in order to solve the above problems, the present invention is to remove the H ₂ S and NH ₃ in the IGCC process and other gasification process using different desulfurization absorbers and NH ₃ catalyst under different operating conditions in different processes. It is an object of the present invention to develop a catalyst-absorber that can be removed and regenerated simultaneously under the same operating conditions in one process.

The present invention to remove the H2S and NH3 at the same time, including 2 to 80% by weight of the active ingredient containing Mo and Ni and 20 to 98% by weight of the support component for dispersing the active ingredient in order to achieve the above object Molybdenum-based catalyst-absorber is provided.
Mo in the active ingredient is preferably in the range of 1 to 30% by weight Ni is in the range of 1 to 30% by weight, in the present specification, the weight% is based on the total weight of the molybdenum-based catalyst-absorber. In addition, the support may include all of the supports known to be capable of dispersing Mo and Ni or Co, and typically include Al ₂ O ₃ or AlPO ₄ .

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Such molybdenum-based catalyst-absorbers of the present invention can be prepared by various known methods such as impregnation method, coprecipitation method, sol-gel and gel mixing method, in order to control the content of the active ingredient and the support ingredient, Precursor materials, such as a nitrate compound and a chloride compound, of each substance are used.

Method for producing a molybdenum catalyst-absorbent of the present invention,

i) dissolving the nitrate compound or chloride compound of the active ingredient and the support ingredient in distilled water, and dropping 0.1-3 M alkaline solution to the precursor solution thus prepared to produce a precipitate;

Ii) aging the resulting precipitate at about 80 ° C. for about 12 hours, and then filtering the precipitate with distilled water until the pH of the filtrate reaches 7 to produce a gelled material; And

Iii) heating the gelled material at a constant rate in an air atmosphere to dry at about 150 ° C. for several hours, and then heating up at a constant rate to bake at about 700 ° C. for several hours.

The alkaline solution is one aqueous solution selected from the group consisting of NaOH, Na ₂ CO ₃ , NH ₄ OH, (NH ₄ ) ₂ CO ₃ , KOH, K ₂ CO ₃ , the concentration of the alkaline solution used is 0.5 ~ 2M It is more preferable that is.

In the step iii), in the case of using AlPO ₄ as the support component, Al is dissolved in distilled water, and then the same number of moles of H ₃ PO ₄ as A1 ₂ O ₃ is added thereto to generate a precursor solution. 0.1-3 M NH ₃ OH and NaOH solutions were added dropwise to the solution to form a precipitate.

Specific examples of the method for producing the molybdenum catalyst-absorbent of the present invention are described in the Examples below.

Each active ingredient of Mo and Ni proposed in the present invention is contained in oil or various organic compounds through various patent documents such as US Patent No. 5010049, No. 5500401, No. 4740354, No. 445266, etc. It is known as a catalyst component which removes sulfur and nitrogen by hydrogenation. However, there has not yet been a catalyst absorbent composed of a combination of these components that can simultaneously remove H ₂ S and NH ₃ .

For this reason, as shown in Fig. 1, the conventional IGCC process includes a coal gasifier 1, a dust collection filter 2 for removing dust, and the like, a desulfurization system 3 using a metal oxide desulfurization agent, and a desulfurization regeneration system ( 4), using a system consisting of NH ₃ decomposition system (5), gas turbine (6), steam turbine (7), etc., first in the desulfurization system (3) in the form of various metal oxides at a temperature of 350 ~ 800 ℃ after removal of the absorbed H ₂ S using a desulfurization absorber, NH ₃ decomposition through the system 5 it was forced to be arranged to remove the NH ₃ decomposition by using a metal oxide catalyst at a temperature of 600 ~ 800 ℃.

However, when the molybdenum-based catalyst-absorber of the present invention is applied to the IGCC process, as shown in Fig. 2, a coal gasifier 1`, a dust collecting filter 2` for removing dust, and the like, H ₂ S and NH It may utilize absorbent recovery system (4`), gas turbine (5`) and steam emitter gas purification system including a simplified than the blank (6`) - <sub>3</sub> simultaneous removal system (3`), catalyst. Here, the H ₂ S and NH ₃ simultaneous removal system 3 'simultaneously removes H ₂ S and NH ₃ gas through a molybdenum-based catalyst-absorber, and the catalyst-absorber regeneration system 4` already uses air. It serves to regenerate the molybdenum-based catalyst-absorber used.

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As described above, when the molybdenum-based catalyst-absorber of the present invention is used to remove H ₂ S and NH ₃ , both of them can be removed at the same time and can be removed with high removal efficiency of 95% or more. In addition, by regenerating the molybdenum catalyst-absorber of the present invention which has completed the removal of H ₂ S and NH ₃ by the regeneration method of the present invention, it can be used many times while maintaining the removal efficiency.

In the present invention, the H ₂ S removal efficiency was calculated by Equation 1 below.

Wherein, "H ₂ S _input concentration" is to sense the concentration of H ₂ S injected into the reactor for the removal of H ₂ S and NH _3, "H ₂ S _output concentration" is to remove the H ₂ S and NH ₃ After that, it means the concentration of H ₂ S released from the reactor.

In addition, NH ₃ removal efficiency in the present invention was calculated by the following equation (2).

In the above formula, " NH ₃ ^input concentration " means the concentration of NH ₃ introduced into the reactor for removing H ₂ S and NH ₃ , and " NH ₃ ^output concentration " is after removing H ₂ S and NH ₃ It means the concentration of NH ₃ released from the reactor.

Hereinafter, the present invention will be described in more detail with reference to examples, but embodiments of the present invention are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, additions, and the like within the spirit and scope of the present invention. Modifications, changes, etc. should be considered to be within the scope of the following claims. Therefore, it will be apparent to those skilled in the art that the manufacturing conditions and experimental conditions set forth in the examples may be arbitrarily selected by the operator within the scope of the present invention within the scope of the present invention.

Example 1

1) Preparation of Catalyst-Absorbent

In this example, catalyst-absorbers MNA1 and MNA2 were prepared according to the coprecipitation method.

After dissolving MoCl ₅ , Ni (NO ₃ ) ₂ and Al (NO ₃ ) ₃ in 500 mL of distilled water to make an aqueous solution, and injected 1.5M NaOH base solution at a rate of 5 mL / min to produce a precipitate, It was aged at 80 ° C. for 12 hours. Then, the precipitate was washed with 4 L of distilled water, dried at 150 ° C. for 4 hours, and calcined at 700 ° C. for 4 hours to obtain MNA1 and MNA2. Here, MNA1 and MNA2 are different in the content of Mo and Ni, MNA 1 is adjusted to 15% by weight of Mo and Ni, respectively, MNA2 is 30% by weight of Mo and Ni, respectively It is adjusted.

2) Removal of H ₂ S and NH ₃ by catalyst-absorber and regeneration of catalyst-absorber

The prepared catalyst-absorbers MNA1 and MNA2 were charged in a quartz reactor, and then the temperature was increased to 650 ° C. using N ₂ . Then, using a bypass to adjust the composition of the reaction gas in the reactor NH ₃ 5000ppm, H ₂ S 10000ppm, H ₂ 11% by volume, CO 9% by volume, CO ₂ 5%, N ₂ balance (balance), H ₂ S and NH ₃ were removed by introducing a catalyst-absorbent. When the removal reaction was completed, the temperature was raised to 700 ° C. again using N ₂ , and after adjusting the gas composition to 3 vol% of O ₂ through the bypass, the catalyst-absorbent was introduced into the reactor to complete regeneration. . The removal of H ₂ S and NH ₃ and the regeneration of the catalyst-absorbent are referred to as one cycle.

Example 2

The same H ₂ S and NH ₃ removal experiments and regeneration were repeated 10 cycles using the MNA1 and MNA2 catalyst-absorbers prepared in Example 1.

Example 3

1) Preparation of Catalyst-Absorbent

In this example, catalyst-absorbers MNAP1 and MNAP2 were prepared by co-precipitation and gel-mixing.

First, MoCl ₅ and Ni (NO ₃ ) ₂ was dissolved in 500 mL of distilled water to make an aqueous solution. Precipitated while injecting 1.5 M NaOH base solution at a rate of 5 mL / min, and then aged at 80 ° C. for 12 hours. To make a gel of A. Then, adjust Al (NO ₃ ) ₃ and H ₃ PO ₄ to a molar ratio of 1 to 1 to dissolve in 500cc distilled water to make an aqueous solution, and 1.5 mol of NH ₄ OH base solution in 5 mL / min It was injected to precipitate so that it was aged for 12 hours at 80 ℃ to make a gel of B. The A gel and the B gel were simultaneously mixed, washed with 12 L of distilled water, dried at 150 ° C. for 4 hours, and calcined at 700 ° C. for 4 hours to obtain MNAP1 and MNAP2. Here, MNAP1 and MNAP2 are different in the content of Mo and Ni, MNAP1 is to adjust the content of Mo and Ni to 10% by weight, respectively, MNAP2 to adjust the content of Mo and Ni to 20% by weight, respectively It is.

2) Removal of H ₂ S and NH ₃ by catalyst-absorber and regeneration of catalyst-absorber

One cycle of the removal of H ₂ S and NH ₃ and the regeneration of the catalyst-absorbent were carried out in the same manner as in Example 1 using the prepared MNAP1 and MNAP2 catalyst-absorbers.

Example 4

Ten cycles of H ₂ S and NH ₃ removal and catalyst-absorbent regeneration were carried out in the same manner as in Example 1 using the MNAP1 and MNAP2 catalyst-absorbers prepared in Example 3.

Hereinafter, the embodiment of MNA, MNAP series of catalyst will be described the results of the H ₂ S and NH ₃ removal of the absorbent capacity and the H ₂ S and NH ₃ removal after regeneration ability.

H ₂ S removal efficiency and NH ₃ removal efficiency for MNA1, MNA2, MNAP1, and MNAP2 catalyst-absorbents according to Examples 1 and 3 described above are shown in FIG. 3. From this, all catalyst-absorbers exhibit 98% H ₂ S removal capacity up to the breakthrough point, while the catalyst-absorbers of MNA1, MNA2 and MNAP1 maintain 95% NH ₃ removal capacity and H ₂ S removal capacity. It can be seen that this decrease is rapidly decreasing when the concentration of H ₂ S is detected at the outlet of the reactor. In addition, in the case of the MNAP2 catalyst absorbent H ₂ S removal capacity is maintained for about 300 minutes while the NH ₃ removal capacity is maintained for about 180 minutes can be seen to decrease.

In addition, it exhibited the H ₂ S and NH ₃ removal test and the regeneration test 10 times one after the H ₂ S removal efficiency and NH ₃ removal efficiency according to the above-described embodiments 2 and 4 in Fig. From this, it can be seen that the MNA1, MNAP1 and MNAP2 catalyst-absorbers maintain the initial reaction activity even after 10 cycles of repetition without any reduction in H ₂ S removal capacity or NH ₃ removal capacity. However, it was confirmed that the MNA2 catalyst-absorber decreased rapidly from 2 cycles of 95% of NH ₃ to 180 minutes and then rapidly decreased, and the H ₂ S removal capacity was maintained up to 10 cycles.

As a result, it was confirmed from the results of the examples that the stability of the MNA1, MNA2 and MNAP1 catalyst-absorber is very excellent, and such a catalyst-absorber can be used for a long time through regeneration rather than disposable.

As described above, the catalyst-absorber of the present invention is excellent in the simultaneous removal of H ₂ S and NH ₃ and has a rapid regeneration ability. In addition, even after repeated removal of H ₂ S and NH ₃ several times, the ability to remove H ₂ S and NH _{3 at} the same time can be maintained stably without decreasing. Therefore, by applying the catalyst-absorber of the present invention to the existing IGCC system, it is possible to remove H ₂ S and NH ₃ more economically and simply.

Claims (9)

2 to 80% by weight of active ingredient including Mo and Ni; And 20 to 98% by weight of the support component for dispersing the active ingredient, The support component is Al ₂ O ₃ or AlPO ₄ , characterized in that the removal of H ₂ S and NH ₃ at the same time, characterized in that the Mo in the range of 1 to 30% by weight and Ni is 1 to 30% by weight. Molybdenum-based catalyst-absorber for delete delete i) dissolving the nitrate compound or chloride compound of the active ingredient including Mo and Ni and a support component thereof in distilled water, and dropping an alkali solution of 0.1-3 M to the precursor solution thus prepared to produce a precipitate; Ii) aging the resulting precipitate at 80 ° C. for 12 hours, and then filtering the precipitate with distilled water until the pH of the filtrate reaches 7 to produce a gelled substance; And Iii) Molybdenum system for simultaneously removing the H ₂ S and NH ₃ comprising the step of heating the gel material in an air atmosphere to dry at 150 ℃ for 4 hours, and then again heated at 700 ℃ for 4 hours Process for preparing a catalyst-absorbent. The method of claim 4, wherein The concentration of the alkaline solution is 0.5 ~ 2M, characterized in that for producing a molybdenum-based catalyst-absorber for removing H ₂ S and NH ₃ at the same time. The method of claim 4, wherein The alkaline solution is NaOH, Na ₂ CO ₃ , NH ₄ OH, (NH ₄ ) ₂ CO ₃ , KOH, K ₂ CO ₃ , characterized in that one aqueous solution selected from the group consisting of, H ₂ S and NH ₃ Method of preparing a molybdenum-based catalyst-absorber for simultaneously removing. The method of claim 4, wherein In the step iii), in the case of using AlPO ₄ as the support component, Al is dissolved in distilled water, and then the same number of moles of H ₃ PO ₄ as A1 ₂ O ₃ is added thereto to generate a precursor solution. A method for preparing a molybdenum catalyst-absorber for simultaneously removing H ₂ S and NH ₃ , characterized in that a precipitate is added dropwise to a solution of 0.5-3 M NH ₃ OH and NaOH. delete delete

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