KR101837807B1 - Catalyst for manufacturing high caloric synthetic natural gas and process for preparing same - Google Patents

Abstract

The present invention relates to a catalyst for the production of synthetic natural gas and a method for producing the same, characterized in that the support contains iron as a first catalyst metal and zinc precursor as a second catalyst metal, a copper precursor, a potassium precursor or a combination thereof A catalyst for producing high calorific value synthetic natural gas is provided.

Description

TECHNICAL FIELD [0001] The present invention relates to a catalyst for producing a high-caloric synthetic natural gas and a method for producing the same. BACKGROUND ART [0002]

The present invention relates to a highly active catalyst used for producing high calorific value synthetic natural gas from a synthesis gas and a process for producing the same.

Generally, a method for producing a synthetic natural gas (SNG) from a gas mixture containing carbon monoxide and hydrogen (syngas) is known.

Commercial plants for synthesizing SNG using carbon monoxide and hydrogen generated by gasification of coal or biomass mainly use nickel (Ni) -based catalysts and produce SNG mainly containing methane by the following reaction formula.

CO + 3H _{2 -} > CH ₄ + H ₂ O

Namely, since the SNG produced by the conventional method mainly contains methane (90-98%), the amount of heat generated is only 9,000 kcal / m ³ even when purified.

Studies on a catalyst capable of producing a high-calorie SNG have been started. Specifically, in Japanese Patent Laid-Open Publication No. 1984-046133, a Co-Mn-Ru / Al ₂ O ₃ catalyst has been proposed for producing a high calorific value synthetic natural gas .

However, there is a problem that the cobalt-based catalyst has a high selectivity to methane among the hydrocarbon products, so that the calorific value of the produced gas is still low. In addition, the yield of C ₂ -C ₄ is only about 20%, and in particular, since the temperature at which the maximum C ₂ -C ₄ yield appears is 300 ° C. or lower, there is a problem that it is difficult to design a commercial reactor. In addition, cobalt itself, which is a major component of the catalyst, is expensive. In the case of Co-Mn-Ru based catalysts, which are typical cobalt catalysts, ruthenium, a noble metal, must be added.

A problem to be solved by the present invention is to provide a catalyst having improved selectivity to C2-C4 by using carbon monoxide and hydrogen in a high-temperature mixed gas such as methane, ethane, propane, butane and the like.

Another object of the present invention is to provide a method for producing the catalyst.

In order to achieve the above object, the present invention provides a catalyst for synthesizing natural gas comprising iron (Fe) as a first catalytic metal and zinc precursor, copper precursor, potassium precursor or a combination thereof as a second catalytic metal, to provide.

The present invention also provides a method for preparing a support, comprising: 1) preparing a support; 2) preparing a metal precursor solution containing an iron precursor as a first catalyst metal and a zinc precursor, a copper precursor, a potassium precursor or a combination thereof as a second catalytic metal; 3) impregnating the support with the metal precursor solution; 4) drying the support impregnated with the metal precursor solution; And 5) calcining the dried support obtained in the step 4) to form a catalyst precursor. The present invention also provides a method for producing a catalyst precursor for synthesizing natural gas.

The present invention also provides a method for preparing a precipitant, comprising the steps of: i) preparing an aqueous precipitant solution in which a precipitant is dissolved; ii) preparing a metal precursor solution containing an iron precursor as a first catalyst metal and a zinc precursor, a copper precursor, a potassium precursor or a combination thereof as a second catalytic metal; iii) adding a metal precursor solution to the precipitation agent aqueous solution to form a precipitate; iv) filtering and washing the precipitate and drying; And v) calcining the dried precipitate to form a catalyst precursor.

The present invention also provides a method for producing a catalyst by reducing and activating a catalyst precursor produced by the above method.

The present invention also provides a synthetic natural gas synthesis method comprising contacting the catalyst with a mixed gas containing hydrogen and carbon monoxide using the catalyst.

The present invention provides a catalyst capable of producing a high calorific value synthetic natural gas having a calorific value of 10,200 kcal / m ³ or more from carbon monoxide and hydrogen obtained from coal or biomass. This results in cost savings of 20 ~ 30% compared to the process using conventional catalysts. As a result, it is expected that the production cost of synthetic natural gas for city gas will be greatly reduced.

FIG. 1 is a graph showing the CO conversion rate and the C2-C4 yield according to the reduction condition change.

According to the present invention, there is provided a catalyst capable of producing a high calorific value synthetic natural gas from carbon monoxide and hydrogen, which can be obtained from coal or biomass.

Hereinafter, preferred embodiments of the present invention will be described.

The catalyst according to the present invention is a catalyst for the production of synthetic natural gas comprising iron (Fe) as a first catalyst metal and zinc (Zn), copper (Cu), potassium (K) or a combination thereof as a second catalyst metal.

According to an embodiment of the present invention, the first catalytic metal and the second catalytic metal may be supported on a support.

The support may be alumina heat-treated at 1,000 to 1,200 ° C for 1 to 5 hours.

According to a preferred embodiment of the present invention, in the case of the supported catalyst, the total amount of supported catalyst metal may be 5 to 30% by weight based on the total weight of the catalyst.

The second catalytic metal may include zinc and copper in a weight ratio of 1 to 10: 1.

Further, copper and potassium may be contained as the second catalyst metal at a weight ratio of 1 to 100: 1.

According to another embodiment of the present invention, the catalyst is prepared by co-precipitation, and the molar ratio of the first catalyst metal to the second catalyst metal is 1: 0.001 to 1: 2.

The present invention also relates to

1) preparing a support;

2) preparing a metal precursor solution containing an iron precursor as a first catalyst metal and a zinc precursor, a copper precursor, a potassium precursor or a combination thereof as a second catalytic metal;

3) supporting the metal precursor solution on the support;

4) drying the support on which the metal precursor solution is supported; And

5) a step of calcining the dried support obtained in the step 4) to form a catalyst precursor.

According to an embodiment of the present invention, the step 1) may be performed by heat-treating the alumina at 1,000 to 1,200 ° C for 1 to 5 hours.

The first or second metal precursor may be selected from the group consisting of a nitrate, a carbonate, an organic acid salt, an oxide, a hydroxide, a halide, a cyanide, a hydroxide salt, a halide salt and a cyanide salt.

In addition, in the step 3), the total amount of the catalyst metal carried may be 5 to 30% by weight based on the total weight of the catalyst.

According to another embodiment, in step 2), zinc and copper may be contained as a second catalyst metal in a weight ratio of 1 to 10: 1.

In addition, in the step 2), copper and potassium may be contained as a second catalyst metal in a weight ratio of 1 to 100: 1.

The step of supporting the metal precursor solution on the support may be performed by a wet impregnation method, a dry impregnation method, a pressure impregnation method, or a mixture in the form of a slurry by spray drying or extrusion drying.

According to another embodiment of the present invention,

i) preparing an aqueous precipitant solution in which the precipitant is dissolved;

ii) preparing a metal precursor solution containing an iron precursor as a first catalyst metal and a zinc precursor, a copper precursor, a potassium precursor or a combination thereof as a second catalytic metal;

iii) adding a metal precursor solution to the precipitation agent aqueous solution to form a precipitate;

iv) filtering and washing the precipitate and drying; And

and v) calcining the dried precipitate to form a catalyst precursor.

The catalyst prepared by the above method may have a molar ratio of the first catalyst metal to the second catalyst metal of 1: 0.001 to 1: 2.

The drying of step 4) or step iv) may be carried out under normal pressure, room temperature to 150 ° C, and 12 to 24 hours.

The firing of the step 5) or the step v) may be carried out under the condition of heating in air at 400 to 800 ° C for 1 to 50 hours.

The present invention also provides a method for producing a catalyst for producing synthetic natural gas by heating and reducing the catalyst precursor produced by the above-described method in a reducing atmosphere.

Hydrogen is mainly used for the reduction and synthesis gas (syngas), which is a mixture of carbon monoxide and hydrogen, or a mixture gas of hydrogen and nitrogen, may be used for improving the performance by cardurizing and nitriding .

The present invention also provides a method for producing synthetic natural gas using the above-described catalyst.

Hereinafter, the present invention will be described more specifically.

According to the present invention there is provided a catalyst for the production of synthetic natural gas comprising iron (Fe) as a first catalytic metal and a zinc precursor, a copper precursor, a potassium precursor or a combination thereof as a second catalytic metal in a support.

The reaction for producing the synthetic natural gas using the catalyst according to the present invention can be carried out according to the following reaction formula.

nCO + (2n + 1) H 2 → C n H 2n + 2 + nH 2 O

Generally, in the Fischer-Tropsch reaction, the cobalt-based catalyst has a problem in that the selectivity of methane increases sharply at high temperature, so that the reaction is performed only at a relatively low temperature of 250 ° C. However, the iron-based catalyst according to the present invention can maintain a high hydrocarbon selectivity even at a high temperature of 300 ° C or higher, preferably 300-600 ° C.

As the temperature increases, the hydrocarbon chain growth is suppressed. Therefore, it is advantageous to conduct the reaction at a high temperature of 300 ° C or more in order to suppress the formation of C 5 or higher hydrocarbons and increase the yield of C 2 -C 4 hydrocarbons. Therefore, iron is selected as the main component of the catalyst instead of cobalt having high methane selectivity at high temperature.

In addition, in the Fischer-Tropsch reaction, manganese (Mn) has been used as a cocatalyst in both iron and cobalt catalysts because it has an effect of improving the conversion of carbon monoxide as a reactant and improving dispersion of iron and cobalt as main components. However, manganese is known to have high olefin selectivity in the product because it does not show H ₂ -spillover. Therefore, in the present invention, the addition of copper (Cu) and / or zinc (Zn) instead of manganese as a cocatalyst improves the paraffin selectivity. Also, potassium was added as a cocatalyst to improve the lifetime and durability of the catalyst.

The catalyst according to the present invention has a high C2-C4 yield at a temperature of 300 DEG C or higher, which is advantageous for producing a high calorific gas.

When the reaction temperature is higher than 600 ° C, the hydrocarbon chain growth is more suppressed and the yield of C2-C4 hydrocarbon may also be lowered. Therefore, Cu having additional hydrogenation performance (H ₂ -spillover) may be further added as a cocatalyst component in order to improve the reaction activity at 300-600 ° C, which is an optimum condition for obtaining the maximum C2-C4 hydrocarbon yield.

According to a preferred embodiment, in the case of the catalyst prepared by the impregnation method, the first and second catalytic metals are supported on the support, and the total amount of the catalytic metal supported is about 5 to about 30 wt% based on the total weight of the catalyst have. When the amount is less than 5% by weight, there is a possibility that the selectivity of the C2-C4 hydrocarbon is lowered in the reaction of a mixed gas of hydrogen and carbon monoxide described below.

The catalyst preparation method by the impregnation method can be carried out through the following steps.

a) preparing a support;

b) preparing a metal precursor solution containing an iron precursor as a first catalytic metal and a zinc precursor, a copper precursor, a potassium precursor or a combination thereof as a second catalytic metal;

c) supporting the metal precursor solution on the support;

d) drying the support on which the metal precursor solution is supported; And

e) firing the dried support obtained in step d) to form a catalyst precursor.

The support may be alumina (Al ₂ O ₃ ) or silica (SiO ₂ ), and may further include other supports. The kind, surface area, pore volume, and average pore size of the support are not particularly limited, but those having a surface area of not less than 10 m ² / g, a pore volume of not less than 0.5 mL / g and an average pore size of not less than 10 nm, And is suitable for producing a catalyst for carrying out the reaction. It is preferable that the support is baked at 300 to 600 ° C under air or an inert gas to remove the impurities before impregnating the solution.

According to a preferred embodiment, the step a) may be performed by heat treating the alumina at 1,000 to 1,200 ° C for 1 to 5 hours. In particular, it is preferable that the alumina support is used by converting γ-alumina into α-phase through heat treatment at a high temperature of about 1,060 ° C.

The first and second metal precursors may be selected from the group consisting of nitrates, carbonates, organic acid salts, oxides, hydroxides, halides, cyanides, hydroxide salts, halide salts and cyanide salts, Nitrates or nitrates may be preferred, but are not particularly limited.

In order to increase the catalytic activity, the catalyst is selected from Group 1A, Group 2A, Group 3A, Group 4A, Group 5A, Group 1B, Group 2B, Group 3B, Group 4B, Group 5B, Group 6B, Group 7B and Group 8B A third metal compound may be further added. The fourth metal compound may be a compound of zirconium, calcium, aluminum, nickel, tungsten, boron, chromium, platinum, magnesium or manganese.

These third metal compounds may be used in the form of salts, oxides, hydroxides, halides, cyanides, oxide salts, hydroxide salts, halide salts, and cyanide salts of nitrates, carbonates and organic acid salts.

The metal precursor solution is prepared by dissolving the metal precursor compound in a solvent. As the solvent, water, alcohols, ethers, ketones and aromatics can be used, and in particular, water, alcohols or a mixture of water and alcohols are preferable.

In order to stably dissolve iron, zinc, copper, potassium ions, etc. in the solution, the pH of the solution is preferably adjusted within a predetermined range. A suitable pH is determined depending on the metal, for example, it is preferably within the range of pH 8 to 11, more preferably 9 to 10. If the pH of the solution deviates greatly from the above-mentioned range, it may become difficult to dissolve it, or there may be an unstable solution which can be precipitated in a short time after the primary dissolution.

The step of supporting the metal precursor solution on the support may be performed by wet impregnation, dry impregnation, vacuum impregnation, or spray-drying or extrusion-drying the slurry mixture. At this time, it is preferable that the amount of the solution used is a volume amount corresponding to the volume of water small pores unique to the porous article.

Further, in the catalyst produced by the method according to the embodiment of the present invention, the preferable amount of the catalyst metal carried on the support is preferably in the range of about 5 wt% to about 30 wt% based on the total weight of the catalyst . When the amount is less than 5% by weight, there is a possibility that the selectivity of high-temperature hydrocarbons, that is, C2-C4 hydrocarbons, is lowered when a mixed gas of hydrogen and carbon monoxide to be described later is reacted.

In the case of the supported catalyst, the content of iron may be 1 to 50 wt%, or 5 to 30 wt%, based on the total weight of the catalyst, and the total content of copper, zinc, potassium, By weight, or 5 to 30% by weight. When copper and zinc are included together, zinc and copper may be contained in a weight ratio of 1 to 10: 1, or a weight ratio of 2 to 4: 1. When potassium is added, iron and potassium can be contained in a weight ratio of 1: 0.1 to 1: 0.01.

It is preferable to appropriately determine the number of impregnation steps so that the metal is finally carried in the amount described above. If the above-mentioned supported amount can not be obtained by only one impregnation, the impregnating and drying step may be repeated several times.

The support after the impregnation of the solution can be formed into a shape such as a cylindrical shape, a trilobate shape, a four-leaf shape, and a spherical shape as necessary.

On the other hand, iron-alumina is one of the catalysts used in the water gas conversion reaction and has a high carbon dioxide selectivity. According to another preferred embodiment of the present invention, the Fe-Zn catalyst prepared by coprecipitation or Fe-Zn -Cu catalyst can exhibit low methane yield and high C2-C4 yield.

In the present invention, the catalyst preparation method according to coprecipitation can be carried out as follows.

i) preparing an aqueous precipitant solution in which the precipitant is dissolved;

ii) preparing a metal precursor solution containing an iron precursor as a first catalyst metal and a zinc precursor, a copper precursor, a potassium precursor or a combination thereof as a second catalytic metal;

iii) adding a metal precursor solution to the precipitation agent aqueous solution to form a precipitate;

iv) filtering and washing the precipitate and drying; And

v) calcining the dried precipitate to form a catalyst precursor.

Specifically, the metal precursor aqueous solution is added to the aqueous solution in which the precipitant is dissolved at a constant rate, preferably 1 to 5 ml or 1 to 3 ml per minute, to form a precipitate. The concentration of the precipitant aqueous solution may be 0.1 to 10M, or 0.5 to 5M. The pH of the precipitant aqueous solution is preferably maintained at about 6 to 8, more preferably about 7 to 0.1. When the addition of the aqueous solution of the metal precursor is completed, filtration and washing can be performed after aging at about 50 to 100 ° C, preferably about 70 to 90 ° C for 1 to 5 hours. As the precipitant, a basic solution such as ammonia or caustic soda (NaOH) or a carbonate such as ammonium carbonate, sodium carbonate and the like can be used

In the catalyst prepared by the co-precipitation method, the molar ratio of the first catalyst metal to the second catalyst metal may be 1: 0.01 to 1: 2, or 1: 0.02 to 1: 1.

According to the embodiment of the present invention, the drying in step d) obtained by the impregnation method or coprecipitation method can be carried out under normal pressure, room temperature to 150 ° C, and 12 to 24 hours.

According to a preferred embodiment of the present invention, the drying may be carried out by gradually increasing the temperature and maintaining the temperature for a certain period of time. (T2) = T1 + 10-50 占 폚, and the third-stage drying temperature T3 = T2 + 10-50 占 폚, where the initial drying temperature is T1, The step drying temperature may be 1 to 24 hours. Is carried out under the conditions of atmospheric pressure, room temperature to 150 ° C, and 12 to 24 hours as a whole.

The firing in the step e) may be performed at 400 to 800 ° C for 1 to 50 hours in the air. Concretely, firing can be carried out in air at 300 to 500 ° C for 1 to 50 hours, and most preferably for 2 to 5 hours.

The present invention also provides a method for producing a catalyst for producing synthetic natural gas by heating and activating the above-mentioned catalyst precursor in a reducing atmosphere.

As the activation treatment, for example, the catalyst before the activation treatment is filled in the reaction column, and a synthesis gas of hydrogen or carbon monoxide or hydrogen and carbon monoxide, or a synthesis gas with nitrogen and hydrogen, Deg.] C, and holding it at a predetermined operating temperature for about 4 to 12 hours.

The present invention also provides a method for producing synthetic natural gas by reacting with a mixed gas comprising hydrogen and carbon monoxide using the catalyst described above.

By reacting a mixed gas containing hydrogen and carbon monoxide at a temperature of 300 to 600 DEG C and a pressure of 0.1 to 7 MPa in the presence of a catalyst produced by a method according to an embodiment of the present invention, So many high calorimetric gases are obtained.

Specifically, a powdery catalyst is filled in a cylindrical high-pressure reaction tube made of stainless steel, and the reaction tube is heated, for example, by an external heater so as to have an internal temperature of 300 to 500 占 폚. In this state, a mixed gas (0.1 to 5 MPa) containing hydrogen and carbon monoxide is circulated to produce a high calorimetric gas.

In addition, a slurry obtained by dispersing the powdery catalyst in a high-boiling point organic solvent in a high-pressure tank having an inlet and an outlet is accommodated, and this high-pressure tank is heated, for example, It is also possible to produce a high calorific gas by circulating a high-pressure gas mixture (0.1 to 20 MPa) containing hydrogen and carbon monoxide into the slurry from the inlet.

The catalyst produced by the method according to the embodiment of the present invention may be used in the form of a powder (for example, an average particle size of 50 to 150 microns) or a granular form such as a pellet of the powder.

The ratio of each component of the above-described mixed gas depends on the type of the desired component selected from among the hydrogenated products and therefore can not be defined in a word. Usually, hydrogen (H ₂ ): carbon monoxide (CO) = 2 to 3: .

In the reaction system to react the gas mixture in the presence of the catalyst, it is possible by setting the temperature and pressure in this range, as a component for the purpose of improving the selectivity of the hydrocarbons, methane and C2-C _4.

The flow rate when the mixed gas is supplied to the high-pressure reaction tube affects the carbon monoxide conversion. In general, if the flow rate of the mixed gas is slow, the conversion of carbon monoxide is increased, but the distribution of each component of the hydrogenated product produced changes and the yield of the desired component also changes. Therefore, it is preferable that the flow rate of the mixed gas is appropriately adjusted in the range of 300 to 600 ° C and 0.001 to 1 g · min / ml from the viewpoint of increasing the yield of the target component, that is, increasing the selectivity.

Hereinafter, the present invention will be described in more detail with specific examples. The following examples are illustrative only and the scope of the present invention is not limited to the following examples.

<Example _{1> 10Fe-2Cu / Al 2} O 3

Γ-alumina (Sasol, Hollow Tablets 5 × 5 × 2, 2) as a support was heat-treated at 1060 ° C. and converted to α-Al 2 O 3. Fe (NO ₃ ) ₃ · 9H ₂ O and Cu (NO ₃ ) ₂ · 3H ₂ O were used as the precursors of iron and copper, and the weight fraction of iron was 10 wt% and the weight fraction of copper was 2 The amount of precursor was calculated to be in wt%, and dissolved in deionized water, and then impregnated on the support by an initial impregnation method. After the support, the catalyst was dried at 110 ° C and calcined at 650 ° C for 5 hours to prepare a catalyst precursor.

A cylindrical continuous flow fixed bed reactor having an inner diameter of 70 mm and an outer diameter of 90 mm was supported by quartz wool at the center inside the reaction tube to fill the catalyst precursor. The temperature in the reactor was measured and controlled by bringing a thermocouple into contact with the center of the catalyst bed. The pressure inside the reactor was adjusted by installing a BPR (back pressure regulator), and the reaction products were analyzed by connecting the bottom of the reactor with the gas chromatography online.

After filling the catalyst precursor, a 10% H2 / He mixed gas was flowed to the top of the reactor, and the catalyst precursor was reduced for 1 hour at 500 ° C. After reducing H2 / CO ratio of 3, to adjust the reaction gas containing the N2 gas as an internal standard at a flow rate of 30 mL / min to the MFC (mass flow controller) it was introduced, and _{(H 2: CO: N 2} = 72: 4: 96), the pressure was adjusted to 10 bar through a back pressure regulator, and the reaction activity was observed while changing the reaction temperature.

<Example 2> 10Fe-2Cu-0.2K / Al 2 O 3

The amount of KNO ₃ as a precursor was calculated in the same manner as in Example 1 except that the weight fraction of potassium was 0.2 wt% in the total catalyst. The iron precursor and the copper precursor in the same amount as in Example 1 were deionized water) and then supported on a support by an initial impregnation method.

<Comparative Example 1> 10Fe / Al ₂ O ₃

A catalyst was prepared in the same manner as in Example 1 except that copper was not added, and the reaction activity was observed.

<Comparative Example 2> 10Co-6Mn-2Cu / Al 2 O 3

A catalyst was prepared in the same manner as in Example 1 except that the manganese precursor Mn (NO ₃ ) ₂ · 4H ₂ O was further added so that the cobalt precursor was used instead of the iron precursor and the manganese fraction was 6 wt% Respectively.

The reaction activity was observed using the catalysts of Examples 1 and 2 and Comparative Examples 1 and 2 at different reaction temperatures. The results are shown in Table 1 below.

catalyst division Reaction temperature (캜) CO conversion (%) CH ₄ Yield (%) C ₂ -C ₄
yield(%) C ₅₊
yield(%) CO ₂
yield(%) 10Fe-2Cu / Al ₂ O ₃ Example 1-1 300 96.8 29.2 25.1 11.9 30.6 Examples 1-2 350 99.1 32.9 28.4 10.8 27.0 Example 1-3 400 97.6 38.2 26.1 8.4 24.9 10Fe-2Cu-0.2K /
Al ₂ O ₃ Example 2-1 300 95.2 29.2 24.4 10.8 29.5 Example 2-2 350 98.8 31.9 28.2 10.0 27.6 Example 2-3 400 97.4 38.1 26.0 9.8 24.0 10 Fe / Al ₂ O ₃ Comparative Example 1-1 400 29.0 18.2 10.8 0 0 Comparative Example 1-2 500 86.8 46.4 14.4 4.7 21.3 10Co-6Mn-2Cu
/ Al ₂ O ₃ Comparative Example 2 250 99.9 60.7 17.3 4.8 17.1

From the above results, it can be seen that the catalyst of Example 1 (10Fe-2Cu / Al ₂ O ₃ ) exhibits a conversion rate of 99.1% at 350 ° C and a high C2-C4 yield of 28.4%.

Also, the catalyst of Example 2 (10Fe-2Cu-0.2K / Al ₂ O ₃ ) was also confirmed to have a high conversion rate and C2-C4 yield as in Example 1. It was confirmed that the performance was maintained for a long period of time as compared with Example 1.

Compared with the catalyst of Comparative Example 1 (10Fe / Al ₂ O ₃ ), the catalyst of Example 1 significantly decreased the temperature at which the activity was exhibited by adding copper to 300 ° C, It is confirmed that the C2-C4 yield is as low as 14.4% because it shows activity from high temperature. Therefore, it can be seen that by adding copper, the temperature showing the reaction activity can be lowered, and thus the C2-C4 yield is improved.

On the other hand, the catalyst of Comparative Example 2 (10Co-6Mn-2Cu / Al ₂ O ₃ ) showed a CO conversion of 99.9% at a low temperature of 250 ° C, but the yield of C2-C4 was only 17.3% Able to know.

<Examples 3 to 5> 10Fe-6M-2Cu / Al 2 O 3

The procedure of Example 1 was repeated except that Mn, Zn, and Mg were added as cocatalyst (M). Metal precursor is a Mn (NO ₃₎ each nitrate _{2 · 4H 2 O, Zn (} NO 3) 2 · 6H 2 O, Mg (NO 3) 2 · 6H 2 O to _{Fe (NO 3) 3 · 9H} 2 O, Cu (NO ₃ ) ₂ · 3H ₂ O in deionized water, and the weight fraction of M was 6 wt% in the total catalyst. The results of the observation of the reaction activity according to the reaction temperature are shown in Table 2 below.

catalyst Example Reaction temperature (캜) CO conversion (%) CH ₄ Yield (%) C ₂ -C ₄
yield(%) C ₅₊
yield(%) CO ₂
yield(%) 10Fe-2Cu / Al ₂ O ₃ 1-1 300 96.8 29.2 25.1 11.9 30.6 1-2 350 99.1 32.9 28.4 10.8 27.0 1-3 400 97.6 38.2 26.1 8.4 24.9 _{10Fe-6Mn-2Cu / Al 2} O 3 3-1 300 79.9 19.1 22.2 10.6 28.0 3-2 350 93.1 26.0 26.7 10.4 30.0 3-3 400 95.2 35.8 24.4 8.1 26.9 _{10Fe-6Zn-2Cu / Al 2} O 3 4-1 300 79.9 19.5 20.9 10.9 28.6 4-2 350 98.3 29.9 30.8 11.6 26.0 4-3 400 96.5 38.0 25.3 8.8 24.4 _{10Fe-6Mg-2Cu / Al 2} O 3 5-1 300 80.7 20.2 19.5 9.9 31.1 5-2 350 90.6 28.6 23.2 8.8 30.0 5-3 400 95.8 37.5 21.5 8.4 28.4

From the above results, it can be seen that Fe-Zn-Cu / Al ₂ O ₃ with zinc added to the catalyst of Example 1 (Fe-Cu / Al ₂ O ₃ ) exhibits a maximum C2-C4 yield of 30.8% at 350 ° C. (Example 4-2).

Examples 6 to 8 Catalyst preparation using coprecipitation method

100 mL of deionized water was placed in a 500 mL three-necked round flask, and the temperature was raised to 80 ° C. The initial pH was adjusted to 7 by adding (NH ₄ ) ₂ CO ₃ aqueous solution used as a precipitant. The metal precursors Fe (NO ₃ ) ₃ .9H ₂ O and Zn (NO ₃ ) ₂ .6H ₂ O are dissolved in 60 mL of deionized water by adjusting the amount to be the desired Fe / Zn molar ratio. The ratio of Fe / Zn was adjusted to 3/1, 10/6, 1/1, and the total metal precursor concentration was maintained at 1M in all cases. The metal precursor solution was added to the flask at a flow rate of 2 mL per minute using a syringe and a syringe pump. As the precipitation agent, a 1 M (NH ₄ ) ₂ CO ₃ aqueous solution was used and the pH was maintained at 7 ± 0.05 by continuously adding to the flask. After the addition of the metal precursor aqueous solution, the mixture was aged at 80 ° C. for 2 hours, and the precipitate was filtered and washed with 2 L of deionized water five times. Thereafter, it was dried at 110 DEG C and calcined at 650 DEG C for 5 hours. The reaction activity was measured in the same manner as in Example 1, and the results are shown in Table 3.

&Lt; Comparative Examples 3 to 5 >

Catalysts were prepared in the same manner as in Examples 6 to 8 except that the manganese precursor Mn (NO ₃ ) ₂ .4H ₂ O was used instead of the zinc precursor, and the reaction activity was measured. Table 3 shows the results.

catalyst division Reaction temperature ( ^o C) CO conversion (%) CH ₄ yield
(%) C ₂ -C ₄
paraffin
yield(%) C ₂ -C ₄
Olefin yield (%) C ₅₊
yield
(%) CO ₂
yield
(%) Fe / Zn
= 3/1 Example 6-1 300 93.1 14.8 36.7 7.6 15.1 18.9 Example 6-2 400 93.5 37.2 17.2 7.6 7.7 23.8 Example 6-3 500 92.7 59.0 7.7 2.3 2.3 21.4 Fe / Zn
= 10/6 Example 7-1 300 93.1 15.8 27.2 8.8 14.4 26.9 Example 7-2 400 93.3 26.9 22.4 8.9 10.7 24.4 Example 7-3 500 92.2 51.4 10.7 3.5 5.4 21.2 Fe / Zn
= 1/1 Example 8-1 300 97.5 16.4 31.1 7.6 15.3 27.1 Example 8-2 400 93.9 32.0 19.0 7.3 9.4 26.2 Example 8-3 500 91.4 54.1 9.5 2.8 3.1 21.9 Fe / Mn
= 3/1 Comparative Example 3-1 300 91.9 17.8 22.7 10.9 13.9 26.6 Comparative Example 3-2 400 93.4 37.5 14.7 9.6 6.7 24.9 Comparative Example 3-3 500 92.4 55.6 8.7 3.5 2.1 22.5 Fe / Mn
= 10/6 Comparative Example 4-1 300 95.5 15.0 21.3 15.5 14.6 29.1 Comparative Example 4-2 400 94.7 30.7 16.4 11.7 10.9 25.0 Comparative Example 4-3 500 93.3 54.2 8.6 4.4 3.7 22.4 Fe / Mn
= 1/1 Comparative Example 5-1 300 96.4 13.2 20.1 16.8 16.3 30.0 Comparative Example 5-2 400 95.3 35.4 13.6 10.6 8.9 26.8 Comparative Example 5-3 500 93.9 54.5 8.5 4.6 4.0 22.3

From the above results, it can be seen that the Fe-Zn catalyst prepared by coprecipitation has a low methane yield and a high C ₂ -C ₄ yield.

Compared with the catalyst of Example 1 (Fe-Cu / Al ₂ O ₃ ), the conversion rates of Examples 6 to 8 (Fe-Zn) were slightly reduced, but the C ₂ -C ₄ yield was greatly increased at 300 ° C.

When Examples 6 to 8 and Comparative Examples 3 to 5 are compared, the yield of Fe-Mn is very high, while in the case of Fe-Zn, dissociation of hydrogen is promoted by ZnO, resulting in lowering of olefin yield and improvement of paraffin yield .

&Lt; Examples 9 to 10 > Production of catalyst by changing the reducing conditions

Zinc was mixed under the same conditions as in Examples 6 to 8 to prepare a catalyst, and the conditions under which the hydrogen was reduced were changed to conduct experiments.

The catalyst groups of Example 9 were reduced using Syngas (CO: H 2 = 1: 1), and the catalyst groups of Example 10 were reduced to a mixed gas containing hydrogen and nitrogen.

FIG. 1 is a graph showing the CO conversion rate and the C2-C4 yield according to the reduction condition change. In FIG. 1, FZ10, FZ5, FZ3 and FZ2 mean that the content of zinc is 10 mol%, 5 mol%, 3 mol% and 2 mol%, respectively. The iron content was 90 mol%, 95 mol%, 97 mol% and 98 mol%, respectively, because of the coprecipitation method. From the results shown in Fig. 1, it was confirmed that by changing the reduction method, CO conversion and C2-C4 yield could be obtained with high performance and life span.

Estimated calorific value

Experimental results of Example 1 (10Fe-2Cu / Al ₂ O ₃ ), Example 4-2 (10Fe-6Zn-2Cu / Al ₂ O ₃ ) and Example 6-1 (Fe / Zn = 3/1) The results of calculation of the expected calorific value based on the results are shown in Table 4 below.

catalyst Reaction temperature ( ^o C) Calorific value of hydrocarbon only
(kcal / m ³ ) The conversion of residual CO, H ₂ and CO ₂ to methane through a two-stage reaction leads to the expected calorific value
(kcal / m ³ ) 10Fe-2Cu / Al ₂ O ₃ 350 13,136 11,747 _{10Fe-6Zn-2Cu / Al 2} O 3 350 13,964 12,161 Fe / Zn = 3 300 17,489 13,123

In Table 4, the calorific value of only hydrocarbon is calculated by excluding the unreacted reactants and carbon dioxide in the product, and the estimated calorific value when converted to methane is calculated assuming that both CO and CO ₂ are converted to methane .

From the above results, it can be seen that the catalyst according to the present invention is advantageous for the production of high-caloric synthetic natural gas.

Claims (21)

A catalyst for the production of synthetic natural gas, comprising iron (Fe) as a first catalyst metal and zinc (Zn) as a second catalyst metal, which is produced by coprecipitation. delete delete delete delete delete The method according to claim 1,
Wherein the molar ratio of the first catalyst metal to the second catalyst metal is 1: 0.001 to 1: 2. delete delete delete delete delete delete delete a) preparing an aqueous precipitant solution in which the precipitant is dissolved;
b) preparing a metal precursor solution containing an iron precursor as a first catalytic metal and a zinc precursor as a second catalytic metal;
c) adding a metal precursor solution to the precipitation agent aqueous solution to form a precipitate;
d) filtering and washing the precipitate and drying; And
e) calcining the dried precipitate to form a catalyst precursor, wherein the catalyst precursor comprises only iron (Fe) as the first catalytic metal and zinc (Zn) as the second catalytic metal. 16. The method of claim 15,
Wherein the molar ratio of the first catalytic metal to the second catalytic metal is 1: 0.001 to 1: 2. 16. The method of claim 15,
Wherein the drying of step d) is carried out under atmospheric pressure, at room temperature to 150 ° C for 12 to 24 hours. 16. The method of claim 15,
Wherein the calcination of the step (e) is carried out at 400 to 800 DEG C for 1 to 50 hours in the air. 15. A method for producing a catalyst for synthesizing natural gas by heating a catalyst precursor prepared by the method of claim 15 in a reducing atmosphere. 20. The method of claim 19,
A method for producing a catalyst for producing a synthetic natural gas by using hydrogen, a mixed gas of carbon monoxide and hydrogen, or a mixed gas of nitrogen and hydrogen, in order to form the reducing atmosphere. A process for the production of synthetic natural gas using the catalyst of any one of claims 1 to 7.

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