KR20150137733A

KR20150137733A - Process for the preparation of fisher-tropsch catalysts with high activity

Info

Publication number: KR20150137733A
Application number: KR1020140066125A
Authority: KR
Inventors: 백영순; 정종태; 이지윤; 박연희; 조원준
Original assignee: 한국가스공사
Priority date: 2014-05-30
Filing date: 2014-05-30
Publication date: 2015-12-09
Also published as: WO2015183061A1

Abstract

The present invention relates to a method for producing a catalyst used for Fischer-Tropsch synthesis. In addition, the present invention provides a method for producing a catalyst precursor for Fischer-Tropsch synthesis, wherein the method comprises the following steps: a) producing a solution composed of a cobalt-containing compound and a polyether compound containing two or more ether groups; b) impregnating the solution into a silica carrier; c) drying the silica carrier impregnated with the solution; and d) plasticizing the dried silica carrier, wherein the content of cobalt contained in the catalyst precursor is approximately 12-25 wt% with respect to the weight of the silica carrier.

Description

TECHNICAL FIELD [0001] The present invention relates to a process for producing a high-activity Fischer-Tropsch catalyst,

The present invention relates to a process for the preparation of a Fischer-Tropsch catalyst for use in the production of hydrocarbons from a synthesis gas.

Fischer-Tropsch synthesis for the production of hydrocarbons from gas mixtures comprising carbon monoxide and hydrogen (synthetic gas) is known.

The conversion technology of liquid hydrocarbons using syngas starts from the reaction of producing synthesis gas through reforming of natural gas and gasification such as coal and biomass. Generally, a Fischer-Tropsch synthesis (FTS) reaction is a reaction for producing hydrocarbon compounds from a syngas, which proceeds on the iron-based and cobalt-based catalysts by the following main representative reactions.

_{nCO + 2nH 2 → (CH 2} ) n + nH 2 O (1)

CO + H ₂ O? CO ₂ + H ₂ (2)

The water-gas shift reaction (WGS) of the reaction formula (2), which is a competitive reaction with the FTS reaction of the reaction formula (1), causes carbon dioxide and hydrogen to react with carbon monoxide and water produced from the reaction formula (1) . Therefore, the water produced in the reaction formula (1) changes the ratio of hydrogen to carbon monoxide in the entire Fischer-Tropsch synthesis reaction.

The catalysts used in the Fischer-Tropsch process have different catalysts depending on the reaction conditions and the desired products. As a representative example thereof, as a component to be used as a main active component of a catalyst, at least one component selected from group 8B (cobalt, ruthenium, iron or nickel) on the standard periodic table and as an enhancer or structural stabilizer to be additionally added, And at least one element selected from Group 1B, Group 2B, Group 3B, Group 4B, Group 5B, Group 6B, and Group 7B elements of Group 1A, Group 3A, Group 4A, Group 5A, Lossy catalysts have been reported to be made and used (U.S. Patent No. 7,067,562).

Although the catalyst used in the Fischer-Tropsch synthesis reaction varies in product distribution depending on the main active ingredient, the Fischer-Tropsch synthesis reaction using a cobalt-based catalyst generally has a reaction of the reaction formula (1) The amount of hydrocarbons (HC) produced by the ASF (Anderson-Shulz-Flory) mechanism is maximized when the molar ratio of H ₂ / CO is 2.0.

In addition, when a cobalt-based catalyst is used, since the reaction proceeds at a lower temperature compared to an iron-based catalyst, it is advantageous in producing paraffinic hydrocarbons such as liquid and wax. Particular attention has therefore been given to catalysts containing cobalt as the catalytically active component.

Further, various studies on the method of increasing the catalytic activity by adding an organic additive in the production of the Fischer-Tropsch catalyst are known.

U.S. Patent No. 7,585,808 discloses a catalyst for the Fischer-Tropsch reaction, which is prepared by treating ruthenium with a catalytically active metal and treating with triethanolamine.

U.S. Patent No. 5,928,983 discloses cobalt-based Fischer-Tropsch catalysts prepared by the addition of oxidizing alcohols, oxidizing aldehydes or oxidizing ketones, especially glyoxal.

U.S. Patent No. 5,968,991 discloses a process for activating a catalyst by impregnating a refractory inorganic carrier with a solution containing cobalt, a multifunctional carboxylic acid represented by HOOC- (CRR ') _n -COOH, .

The present invention relates to a catalyst for synthesis of a Fischer-Tropsch synthesis reaction, which is superior in catalytic activity and stability as compared with cobalt-based catalysts which have been generally reported, and which has a high boiling point and improved selectivity to hydrocarbons and light hydrocarbons Cobalt-based catalysts.

According to an aspect of the present invention,

a) preparing a solution of a cobalt-containing compound and a polyether compound containing two or more ether groups,

b) the step of impregnating the solution of a silica (SiO ₂₎ carrier,

c) drying the silica carrier impregnated with the solution, and

d) calcining the dried silica carrier to form a catalyst precursor,

Wherein the cobalt content of the catalyst precursor is from about 12 wt% to about 25 wt%, based on the weight of the silica support, of a catalyst precursor for Fischer-Tropsch synthesis.

The present invention also provides a process for synthesizing hydrocarbons comprising reducing and activating a catalyst precursor produced by the process and contacting the catalyst precursor with a mixed gas comprising hydrogen and carbon monoxide.

The catalyst according to the present invention is used in the Fischer-Tropsch synthesis reaction to improve the conversion of carbon monoxide and decrease the selectivity to methane, which is a major by-product, and thus has an excellent effect of improving the yield to high boiling point hydrocarbons and light olefins.

1 is a graph showing the activity of catalysts obtained from catalyst precursors according to Examples 1 to 5. FIG.
2 is a graph showing the activity of catalysts obtained from the catalyst precursors according to Examples 1, 6 and 7;

According to the present invention, there is provided a process for producing a catalyst precursor for Fischer-Tropsch synthesis which has a high CO conversion and exhibits high activity.

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

The process for preparing a catalyst precursor for Fischer-Tropsch synthesis according to the present invention comprises:

b) the step of impregnating the solution of a silica (SiO ₂₎ carrier,

c) drying the silica carrier impregnated with the solution, and

d) calcining the dried silica carrier to form a catalyst precursor,

According to a preferred embodiment of the present invention, the cobalt content of the catalyst precursor is preferably about 15% to about 20% by weight based on the weight of the silica carrier.

According to a preferred embodiment of the present invention, the method may further comprise the step of adding a second metal compound to the solution of step a).

Wherein the second metal compound is a compound of one or more 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 elements to be.

Particularly preferably, the second metal compound may be a compound of zirconium, iron, calcium, aluminum, zinc, nickel, copper, tungsten, boron, chromium, platinum, magnesium or manganese.

The second metal compound may be selected from the group consisting of nitrates, carbonates, organic acid salts, oxides, hydroxides, halides, cyanides, hydroxide salts, halide salts and cyanide salts.

The polyether compound may be an aliphatic, aromatic, or cyclic polyether compound.

The aliphatic polyether compound may be paraformaldehyde, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene ether glycol or a dialkyl ether compound thereof.

According to an embodiment of the present invention, the cyclic polyether compound is preferably a crown ether.

In the present invention, the polyether compound is preferably used in a ratio of 0.01 to 2 moles per mole of cobalt.

In an embodiment of the present invention, it is preferable that the method further comprises a step of calcining the carrier in air at 400 to 1000 占 폚 before impregnating the carrier with the solution.

The step of impregnating the carrier with the solution of the cobalt-containing compound and the polyether compound is carried out by wet impregnation, dry impregnation, vacuum impregnation or slurry-form mixture by spray drying or extrusion drying But are not limited to these.

According to embodiments of the present invention, the content of cobalt metal may range from about 12 to about 25 wt.%, Based on the weight of the silica support, and the catalyst precursor is reduced and used as a catalyst for FT synthesis .

In the present invention, drying in step c) may be carried out under normal pressure, room temperature to 150 ° C, and 12 to 24 hours, and firing in step d) may be carried out at 150 to 300 ° C to 500 ° C, Over a period of time. It is preferable that firing is performed in an inert gas atmosphere.

The present invention also provides a process for synthesizing hydrocarbons comprising reducing and activating the catalyst precursor thus prepared and contacting the activated catalyst with a mixed gas comprising hydrogen and carbon monoxide.

Hereinafter, the present invention will be described more specifically.

In the method for producing a catalyst precursor for FT synthesis, cobalt is used as a transition metal capable of hydrogenating carbon monoxide.

The cobalt may be at least one selected from the group consisting of salts of cobalt nitrate, cobalt carbonate and cobalt organic acid salts, cobalt oxides, cobalt hydroxides, cobalt halides, cobalt cyanides, cobalt oxide salts, cobalt hydroxide salts, cobalt halide salts, and cobalt cyanide salts And at least one kind of cobalt compound selected from the group consisting of Of these, cobalt nitrate or cobalt nitrate is particularly preferable. The cobalt compound may be used singly or as a mixture of two or more kinds.

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 second metal compound may be further added. According to a preferred embodiment of the present invention, the second metal compound may be a compound of zirconium, iron, calcium, aluminum, zinc, nickel, copper, tungsten, boron, chrome, platinum, magnesium or manganese.

These second 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. Of these, nitrates or nitrates are particularly preferable. The second metal may be used singly or in a mixture of two or more.

The polyether compound used in the present invention is preferably an aliphatic, unsaturated hydrocarbon, aromatic or cyclic polyether compound.

The aliphatic polyether compound may be selected from paraformaldehyde, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene ether glycol or dialkyl ether compounds thereof.

More preferably, the polyether compound has 3 to 15 carbon atoms.

The cyclic polyether compound is preferably a crown ether.

The cobalt compound and the polyether compound are dissolved in a solvent to prepare a solution (impregnation solution). 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.

The polyether compound is preferably blended in an amount of 0.01 to 2 mol, more preferably 0.1 mol or more, per mol of the metal atom contained in the cobalt compound in the polyether compound to react with the cobalt compound, You can control his amount.

In the solution containing the cobalt compound and the polyether compound, it is presumed that the cobalt compound is ionized to generate cobalt ions, and the polyether compound is coordinated around the cobalt ion to form a complex. Also, a complex means a complex in which a ligand having two or more coordinating atoms forms a ring and is bonded to a central metal.

In order to stably dissolve the cobalt ions 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, when a Co compound is used, the pH is preferably in the range of 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 support may be a silica (SiO _2), it may further include other carriers. The kind, surface area, pore volume, and average pore size of the carrier are not particularly limited, but those having a surface area of 10 m ² / g or more, a pore volume of 0.5 mL / g or more, and an average pore size of 10 nm or more And is suitable for producing a catalyst for carrying out a hydrogenation reaction.

It is preferable that the carrier is baked at 300 to 600 ° C under air or an inert gas to remove the impurities before impregnating the solution.

For impregnating the silica containing solution containing the chelate complex, for example, wet impregnation, dry impregnation and vacuum impregnation may be employed. 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 cobalt metal supported on the silica carrier is about 12% by weight to about 25% by weight based on the weight of the silica carrier Is preferably in the range of about 15% to about 20% by weight. When the supported amount is less than 12% by weight, the rate of change of carbon monoxide may decrease during the reaction of the mixed gas of hydrogen and carbon monoxide described below. On the other hand, in the case of carrying more than 25% by weight in a large amount, it is not expected to improve the carbon monoxide conversion rate by the amount supported.

When the second metal compound is used, the second metal may be supported on the silica support together with the cobalt metal, wherein the second metal may be used in a proportion of 0.03 to 0.3 mol based on 1 mol of the cobalt metal have.

It is preferable to appropriately determine the number of times of impregnation so that the cobalt metal is finally carried in the amount described above. If the cobalt loading is not achieved by one impregnation, the impregnation and drying process may be repeated several times.

The silica impregnated with the solution can be molded into a shape such as a cylindrical shape, a trilobate shape, a four-leaf shape, or a spherical shape, if necessary.

The drying can be performed by a normal-pressure drying method or a reduced-pressure drying method. For example, in the case of the atmospheric pressure drying method, it can be carried out under atmospheric pressure at a temperature of room temperature to 150 ° C for 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.

Subsequently, firing can be carried out under air or an inert gas at 300 to 500 ° C for 1 to 50 hours, and most preferably for 2 to 5 hours. By the above-described method, a catalyst in which cobalt oxide capable of hydrogenating carbon monoxide is highly dispersed on a carrier is produced. The obtained catalyst can be used for the Fischer-Tropsch synthesis reaction after the activation treatment is applied according to a certain rule.

As the activation treatment, for example, the catalyst before the activation treatment is filled in the reaction column, the synthesis gas of hydrogen or carbon monoxide or hydrogen and carbon monoxide is circulated as an activator, the mixture is gradually heated to 200 to 500 ° C, For about 4 to 12 hours.

By reacting a mixed gas containing hydrogen and carbon monoxide at a temperature of 150 to 350 DEG C and a pressure of 0.1 to 5 MPa in the presence of a catalyst produced by a method according to an embodiment of the present invention, , A hydrogenation product containing a diesel fuel component is obtained.

Specifically, a cylindrical stainless steel high-pressure reaction tube is filled with the catalyst in the form of a powder, and the reaction tube is heated, for example, by an external heater so as to have an internal temperature of 150 to 350 占 폚. In this state, a hydrogenation product is produced by flowing a mixed gas (0.1 to 5 MPa) containing hydrogen and carbon monoxide.

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 the high-pressure tank is heated, for example, It is also possible to produce a hydrogenation product 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-mentioned mixed gas can not be defined in one word because it depends on the kind of the desired component to be selected in the hydrogenation product. Usually, hydrogen (H ₂ ): carbon monoxide (CO) . For example, when the selected component is a diesel fuel oil component, it is preferable to use a mixed gas of hydrogen (H ₂ ): carbon monoxide (CO) = 2: 1 as the mixed gas.

In the reaction system to react the gas mixture in the presence of the catalyst, the temperature and by the pressure being set within the above range, as a component of interest from methane of C ₁ C ₄ butane and gasoline of C ₅ ~ C ₉ It becomes possible to arbitrarily select a fuel oil component, a diesel fuel oil component of C ₁₀ to C ₂₀ and a high boiling paraffin such as wax.

The flow rate when the mixed gas is supplied to the high-pressure reaction tube affects the carbon monoxide conversion. Generally, if the flow rate of the mixed gas is decreased, the rate of change of carbon monoxide increases, but the distribution of each component of the hydrogenated product to be produced changes and the yield of the desired component also changes. Therefore, it is preferable that the flow rate of the mixed gas is suitably adjusted at 0.1 to 20 MPa and 150 to 350 DEG C 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.

&Lt; Preparation Example: Preparation of silica carrier &

Aerolyst 3041 (SiO ₂ , excluded type, 0.40 to 0.46 kg / L, 99 +%) of Evonik Co. was prepared as a silica support for supporting cobalt metal. The silica was heated at a rate of 2 캜 / min and calcined at 450 캜 for 10 hours. The calcined silica was crushed and prepared in a size of 100 to 300 mesh. As a result of BET measurement, silica having a specific surface area of about 150 m 2 / g, a pore volume of about 0.80 cm 3 / g, and a pore size of about 20 nm was prepared.

&Lt; Example 1 >

Polyethylene glycol dimethyl ether and Co (NO ₃ ) ₂ .H ₂ O were completely dissolved in distilled water so that the molar ratio of polyethylene glycol dimethyl ether and cobalt was 1: 1, and then impregnated with 8.8 g of the silica. After impregnation, it was dried at 110 DEG C for 24 hours. Thereafter, the temperature was raised at a rate of 1 ° C / min at 130 ° C, maintained at that temperature for 3 hours, then increased at a rate of 0.5 ° C / min at 150 ° C, and then maintained for 3 hours. Thereafter, the mixture was heated to 350 ° C at a rate of 0.5-1 ° C / min, and then maintained for 3 hours to obtain an 18 wt% Co / SiO ₂ catalyst precursor.

&Lt; Example 2 >

The procedure of Example 1 was repeated except that the content of cobalt in Example 1 was changed to 12 wt% instead of 18 wt%, and zirconium (Zr) as a second metal was further added at a 1/16 molar ratio relative to 1 mol of cobalt. To prepare a catalyst precursor.

&Lt; Example 3 >

Except that the content of cobalt in Example 1 was changed to 12% by weight instead of 18% by weight and the amount of iron (Fe) as a second metal was further added at a 1/16 molar ratio relative to 1 mole of cobalt. 1, a catalyst precursor was prepared.

Except that the content of cobalt in Example 1 was changed to 12% by weight instead of 18% by weight and the content of zinc (Zn) as a second metal was further added at a 1/16 molar ratio relative to 1 mole of cobalt. 1, a catalyst precursor was prepared.

&Lt; Example 5 >

Except that the content of cobalt in Example 1 was changed to 12% by weight instead of 18% by weight and the amount of calcium (Ca) as a second metal was further increased to 1/16 by mole relative to 1 mole of cobalt. 1, a catalyst precursor was prepared.

&Lt; Example 6 >

A catalyst precursor was prepared in the same manner as in Example 1 except that the content of cobalt in Example 1 was changed to 12 wt% instead of 18 wt%.

&Lt; Example 7 >

A catalyst precursor was prepared in the same manner as in Example 1 except that the content of cobalt in Example 1 was changed to 24 wt% instead of 18 wt%.

Fisher Tropsch reaction experiment

1 g of each of the catalyst precursors prepared in Examples 1 to 7 was mixed with 3 g of a catalyst diluent (quartz powder), and the mixture was accommodated in a high-pressure fixed bed reactor, and activation treatment was performed at 723 K in a hydrogen stream. Thereafter, a mixed gas containing hydrogen and carbon monoxide was introduced, and FT reaction was carried out under the following conditions to produce a hydrogenated product.

Reaction temperature 200 ° C, voltage 20 bar, H ₂ / CO = 2 (containing 4% nitrogen as the GC internal standard), SV = 4000 hr ^-1 [standard cc syngas / atm conditions)

The activity (mol / g-Co / hr) was investigated by in-line GC analysis after the activation of each catalyst was stabilized 15 hours after the initiation of the reaction. The obtained results are shown in Fig. 1 and Fig.

Activity: Converted CO mol / g Co hr

As can be seen from the results of Figs. 1 and 2, the catalyst according to the present invention of Examples 1 to 7 exhibits excellent activity. In particular, it can be seen that the catalyst of Example 1 exhibits the best results. Thus, a catalyst precursor according to the present invention containing a certain amount of a cobalt metal relative to a silica carrier can be used as a catalyst useful in FT synthesis.

Claims

a) preparing a solution containing a cobalt-containing compound and a polyether compound containing at least two ether groups,
b) impregnating the silica carrier with the solution,
c) drying the silica carrier impregnated with the solution, and
d) calcining the dried silica carrier to form a catalyst precursor,
Wherein the cobalt content of the catalyst precursor is from about 12 wt% to about 25 wt%, based on the weight of the silica support.

The method according to claim 1,
Wherein the cobalt content of the catalyst precursor is about 15% to about 20% by weight based on the weight of the silica support.

The method according to claim 1,
Further comprising adding a second metal compound to the solution of step a). &Lt; RTI ID = 0.0 > 11. < / RTI >

The method of claim 3,
Wherein the second metal compound is a compound of one or more 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 elements Wherein the catalyst precursor is a catalyst precursor.

5. The method of claim 4,
Wherein the second metal compound is a compound of zirconium, iron, calcium, aluminum, zinc, nickel, copper, tungsten, boron, chromium, platinum, magnesium or manganese .

5. The method of claim 4,
Wherein the second metal compound is selected from the group consisting of nitrate, carbonate, organic acid salt, oxide, hydroxide, halide, cyanide, hydroxide salt, halide salt and cyanide salt. For preparing a catalyst precursor.

The method according to claim 1,
Wherein the polyether compound is an aliphatic, aromatic, or cyclic polyether compound.

8. The method of claim 7,
Wherein the aliphatic polyether compound is paraformaldehyde, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene ether glycol, or a dialkyl ether compound thereof; and a method for producing a catalyst precursor for Fischer- .

8. The method of claim 7,
Wherein the cyclic polyether compound is a crown ether.

The method according to claim 1,
Wherein the polyether compound is used in a ratio of 0.01 to 2 moles per mole of cobalt.

The method according to claim 1,
Further comprising the step of calcining the carrier in air at 400 to 1000 占 폚 before impregnating the carrier with the solution.

The method according to claim 1,
Characterized in that the step of impregnating the carrier of step b) with the carrier is carried out by wet impregnation, dry impregnation, vacuum impregnation or a mixture in slurry form by spray drying or extrusion drying. A method for preparing a catalyst precursor for Tropsch synthesis.

The method according to claim 1,
Wherein the drying in step c) is carried out under atmospheric pressure, from room temperature to 150 ° C for 12 to 24 hours.

The method according to claim 1,
Wherein the calcination in step d) is carried out at 150? To 300? 500? For 1 to 50 hours.

15. The method of claim 14,
Wherein the calcination is performed in an inert gas atmosphere.

16. A catalyst precursor produced by the process of any one of claims 1 to 15.

16. A process for synthesizing hydrocarbons comprising reducing and activating the catalyst precursor of claim 16 and contacting the activated catalyst with a mixed gas comprising hydrogen and carbon monoxide.