KR20120131852A - Preparing method of Catalysts for the Fischer-Tropsch synthesis - Google Patents

Abstract

PURPOSE: A manufacturing method of a fisher-tropsch reactive catalyst is provided to increase the activity of the catalyst by easily transferring resultant products and reactive products on the surface of the catalyst. CONSTITUTION: A manufacturing method of a fisher-tropsch reactive catalyst includes the following steps: a precursor solution of a reforming agent is impregnated into a support, and the impregnated product is dried and plasticized to reform the surface of the support; a cobalt precursor solution is impregnated on the surface reformed support, and the impregnated product is dried and plasticized to immerse cobalt; an enhancer precursor solution is impregnated on the cobalt carried support, and the impregnated product is dried and plasticized to become a catalyst; the catalyst is washed with a polar solvent to prepare suspension in which catalyst particles and microparticles of 10um or less separated from the surfaces of the catalyst particles are floated; and the catalyst particles are precipitated to remove the microparticles.

Description

Preparation method of catalysts for the Fischer-Tropsch synthesis}

The present invention relates to a method for preparing a Fischer-Tropsch reaction catalyst for producing liquid hydrocarbons using syngas.

The improvement of the catalyst for Fischer-Tropsch (FT) reactions in the development of Gas-to-Liquids (GTL) technology, which is in the spotlight as an alternative to cope with the recent rapidly rising oil price problem, is a competitive advantage of the GTL technology. It is directly related to the improvement. In particular, according to the improvement of the catalyst for the F-T reaction can improve the thermal efficiency and carbon utilization efficiency of the GTL process, it is also possible to optimize the design of the F-T reaction process. Iron and cobalt-based catalysts are mainly used for the FT reaction, but the characteristics of the cobalt-based catalysts are 200 times more expensive than iron-based catalysts, but they have high activity, long life, and low carbon dioxide. The yield of paraffinic hydrocarbons is high. However, at a high temperature, there is a problem of producing a large amount of methane, so it can be used only as a low temperature catalyst. Since expensive cobalt is used, it must be well dispersed on a high surface area stable support such as alumina, silica, and titania. It is a situation that is used in the form of addition of a noble metal promoter, such as, Re. Iron-based catalysts feature the lowest cost of FT catalysts, low methane production at high temperatures, high selectivity of olefins in hydrocarbons, and products are used as raw materials for the chemical industry as light olefins or alpha olefins in addition to their use as fuels. Many by-products such as alcohols, aldehydes and ketones are produced.

In general, the Fischer-Tropsch synthesis catalyst is largely prepared by three methods. The first method is impregnation, in which a catalyst prepared by dissolving a catalyst precursor is impregnated into a catalyst support such as alumina, silica, and titania having a large surface area, followed by drying and calcining. Among the impregnation methods, incipient wetness impregnation is the most widely used method and is prepared by supporting an impregnation solution corresponding to the pore volume of the catalyst support. This method is mainly used in the preparation of cobalt-based catalysts for Fischer-Tropsch reactions. The second is coprecipitaion, in which a precipitant solution is added to a solution in which a catalyst, a promoter, and a support precursor are dissolved together. The precipitant is co-precipitated with a catalyst component and a basic solution such as ammonia or sodium hydroxide (NaOH). Or carbonates such as ammonium carbonate, sodium carbonate and the like. This method is mainly used in the preparation of iron-based catalysts for Fischer-Tropsch reactions. The third is a sol-gel method, in which a catalyst precursor is dissolved in a relatively high boiling point organic solvent, mixed with an alkoxide of a support component, and then slowly hydrolyzed to prepare a catalyst having excellent dispersion.

Fischer-Tropsch catalyst for bubble column slurry reactor is involved in the reaction in the slurry phase, it is preferable to have a particle size of 10 ~ 300 ㎛ in order to distribute the catalyst uniformly in the reactor. Alumina and silica are mainly used as a support for the cobalt catalyst for the bubble column slurry reactor, and P, Si, La, and B are pretreated as a support stabilizer for the alumina support, and Zr is mainly used for the silica support. do. The amount of cobalt supported on the support is 10 to 30% by weight, and in some cases, precious metals such as Pt, Ru, and Re may be supported by 0.01 to 0.5% by weight as a catalyst enhancer.

On the other hand, in the bubble column slurry reactor, the catalyst flows violently in the reactor, so that surface microparticles of less than 10 μm may be broken by friction of the catalyst particles, and these microparticles are to be separated by using a filter using a filter. When the amount is large, the filter is loaded to reduce the separation efficiency, and it acts as an adhesive in the reactor to agglomerate the catalyst particles to form large particles that are difficult to float by the flow or to agglomerate the catalyst on the inner wall of the reactor. There was a problem causing it.

Accordingly, the present inventors have previously cleaned the cobalt-based Fischer-Tropsch catalyst particles for the bubble column slurry reactor to remove the microparticles of less than 10 ㎛ physically attached to the surface of the catalyst particles before applying them to the reaction. In order to solve the side effects caused by, additionally by washing the catalyst was found the effect that the catalytic activity is further enhanced to complete the present invention. That is, an object of the present invention is to provide a method for preparing a catalyst for Fischer-Tropsch reaction for solving the filter load problem in the catalyst agglomeration and wax separation due to the catalyst microparticles.

The present invention

Impregnating the support with a modifier precursor solution followed by drying and firing to modify the surface of the support;

Impregnating a cobalt precursor solution on the surface-modified support, followed by drying and firing to support cobalt;

Preparing a catalyst by impregnating a cobalt-supported support with a promoter precursor solution, followed by drying and calcining;

Washing the catalyst with a polar solvent to prepare a turbid solution in which catalyst particles and fine particles less than 10 μm separated from the surface of the catalyst particles are suspended; And

Depositing the catalyst particles in the turbid solution, and removing the fine particles by inclining the filtrate in which the fine particles are suspended;

It features a method for producing a catalyst for Fischer-Tropsch reaction comprising a.

The catalyst for Fischer-Tropsch reaction prepared by the present invention can reduce the amount of microparticles generated in the bubble column slurry reactor by removing the microparticles of less than 10 ㎛ physically attached to the catalyst in advance, thereby fine Agglomeration of the catalyst by the particles and the separation of the product wax from the catalyst particles using the filter can reduce the load of the filter due to the fine particles. In addition, by removing the fine particles adhering to the surface of the catalyst particles it is easy to move the product and reactants on the surface of the catalyst has the effect of enhancing the activity of the catalyst.

1 is a scanning electron micrograph of the catalyst particles prepared in Example 1 and Comparative Example 1, (a) is a catalyst particle prepared in Example 1, (b) is an enlarged photograph of the surface thereof, (c) Is a catalyst particle prepared in Comparative Example 1, (d) is an enlarged photograph of the surface thereof.
2 is a scanning electron micrograph of the microparticles separated by washing.
3 is a photograph obtained after the catalyst prepared in Example 1 (a) and Comparative Example 1 (b) after the slurry reaction after the catalyst and wax in the reactor. In the photograph (a) of the product reacted with the catalyst prepared in Example 1, the catalyst particles are precipitated in the wax and mostly present at the bottom, so that the wax layer does not contain the catalyst and the wax and the catalyst are cleanly separated. On the other hand, the photocatalyst (b) of the catalyst and the wax obtained by precipitation of the catalyst prepared in Comparative Example 1 after the reaction can be seen that the fine catalyst particles do not completely sink, but float in the wax layer.

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

The present invention relates to a method for preparing a catalyst for Fischer-Tropsch reaction in which fine particles physically attached to the surface of a cobalt catalyst applied to a bubble column slurry reactor are removed by washing.

In general, the fine particles attached to the catalyst particles in a fixed bed reactor or a fluidized bed reactor do not cause a significant problem in the process, but in the Fischer-Tropsch bubble column reactor (SBCR), the reaction product liquid hydrocarbons are combined with the catalyst particles. It must be separated by a filter. At this time, the fine particles adhered to the catalyst particles are broken during the catalytic reaction to reduce the efficiency of the filter, it is necessary to control the production thereof. Although many studies have focused on improving the physical strength of catalyst particles, it is easier to realize that the removal of microparticles during catalysis can be reduced by simply removing the microparticles attached to the large catalyst particles. It was found and completed the present invention.

In the step of modifying the surface of the support by impregnating the support with a modifier precursor solution and then drying and calcining, the support may use alumina or silica. It is preferable to use alumina having a spherical shape of 60% having a particle size of 45 to 90 μm and 40% having a particle size of 90 to 150 μm. Silica has 50 to sufficiently fluidize in a slurry reactor. It is preferable to use those having a particle size of ˜300 μm. Such supports can cause phase changes during Fischer-Tropsch reactions to accelerate catalyst deactivation or degrade thermal stability, thereby enhancing activity and stability by supporting a modifier to modify the surface. As a modifier to be used, when alumina is selected as the support, at least one selected from phosphorus (P), silicon (Si), lanthanum (La), and boron (B) may be used, and oxides, acetates, hydrochlorides, Precursors in the form of nitrates, or mixtures thereof, are dissolved in a solvent such as deionized water, alcohol, etc., and then impregnated into the support. In addition, when silica is selected as the support, the modifier may use one or more selected from aluminum (Al), zirconium (Zr), and phosphorus (P). Similarly, the oxide, acetate, hydrochloride, nitrate, or mixture thereof of the modifier may be used. The precursor in the form of is dissolved in a solvent such as deionized water or alcohol and impregnated into the support.

The support is impregnated with a modifier precursor solution, followed by drying and firing to modify the surface of the support. The drying is preferably carried out at a temperature of 100 ~ 200 ℃ in terms of drying rate and process efficiency. In addition, the firing is preferably carried out at 300 ~ 800 ℃, if the firing temperature is less than 300 ℃ it is difficult to obtain the desired surface modification effect, if it exceeds 800 ℃ due to clogging of micropores by sintering (sintering) It is not preferable because the specific surface area of the support can be greatly reduced. The amount of the support of the modifier supported by the calcination is preferably 0.5 to 10% by weight based on the total weight of the catalyst. When the amount is less than 0.5% by weight, the beneficial effect of the support is insignificant. Blocking the fine pores may cause a problem that the activity of the catalyst rather falls due to the reduction of the specific surface area.

After modifying the surface of the support, a step of impregnating a cobalt precursor solution into the support, followed by drying and firing to carry cobalt is carried out. Cobalt nitrate, acetate salt, chloride salt, or a mixture thereof may be used as the cobalt precursor, which is dissolved in a solvent such as deionized water or alcohol and impregnated in the support. After drying at 100 ~ 200 ℃ and firing at 300 ~ 800 ℃ to support the cobalt on the support. If the firing temperature is too low, the cobalt precursor component may remain in the catalyst to increase side reactions. If the firing temperature is too high, the particle size may increase due to the sintering of the active ingredient cobalt, thereby decreasing dispersibility or decreasing the specific surface area of the catalyst. It is not desirable because it can be. The supported amount of cobalt is preferably 15 to 30% by weight based on the total weight of the catalyst, but if the supported amount is less than 15% by weight, there may be a problem in that the catalytic activity is deteriorated. The fine pores may be blocked, leading to a decrease in activity.

After the cobalt is supported on the support, a catalyst is prepared by supporting the enhancer by impregnation. The promoter may be selected from one or more selected from platinum, ruthenium (Ru) and rhenium (Re), and the precursor, in the form of oxides, acetates, hydrochlorides, nitrates, or mixtures thereof, is dissolved in a solvent to provide a solution to the support. Impregnate Drying and firing conditions are the same as the cobalt loading conditions described above, the amount of the promoter is preferably 0.01 to 0.5% by weight based on the total weight of the catalyst. If the supported amount is less than 0.01% by weight, the beneficial effect of the addition of the enhancer is insignificant, and even if it exceeds 0.5% by weight, the effective benefit of the increase is insignificant.

When the modifier, cobalt, and enhancer are sequentially supported on the support by the impregnation method, a catalyst for Fischer-Tropsch reaction having a particle size of 300 μm or less is prepared. In the bubble column slurry reaction, particles of a certain size must be used to float the catalyst particles. In the past, a sieve was used to select catalyst particles. However, the method using a sieve is suitable for selecting small particles and large particles, but there is a limit to removing fine particles smaller than 10 μm physically attached to the catalyst particles. As mentioned above, such fine particles add a load to the filter when the reactant is separated from the filter, and cause a problem of lowering the reaction efficiency by agglomerating the catalyst particles or attaching the catalyst in the reactor. When preparing the catalyst by supporting the active material by the coprecipitation method, since washing is required in the process of recovering the precipitate after the coprecipitation, fine particles can be separated in advance, but as in the present invention, a cobalt-based fischer-treat for a bubble column reactor The Ropsch catalyst is prepared by impregnating a cobalt solution on a support such as alumina, silica or titania to enhance the activity per unit weight of expensive cobalt. When the high content of cobalt as an active material is supported by 15 to 30% by weight using the impregnation method as in the present invention, all of the cobalt precursors cannot enter the pores of the support, resulting in fine particles of less than 10 μm on the surface of the support.

In order to solve this problem, the present invention includes washing the prepared catalyst with a polar solvent to remove fine particles of less than 10 ㎛. Removing the fine particles by washing comprises the steps of washing the prepared catalyst with a polar solvent to prepare a turbid solution in which the catalyst particles and fine particles less than 10 ㎛ separated from the surface of the catalyst particles suspended; And depositing the catalyst particles in the turbid solution and removing the fine particles by decanting the filtrate in which the fine particles are suspended. .

Generally, a filtration method is used to remove impurities by washing. However, when using a filtration method using a filter to remove fine particles of less than 10 ㎛ it is difficult to effectively filter out the fine particles, such as the load is generated in the filter to increase the filtration time, this problem is a process efficiency in the mass production process It causes dropping problems. In the present invention, 10 to 300 ㎛ catalyst particles are precipitated in the polar solvent, and less than 10 ㎛ fine particles are suspended, then fine particles are effectively suspended by inclining the filtrate suspended fine particles.

As the polar solvent, one or more selected from deionized water, methanol, ethanol, propanol and butanol may be used. In addition, the washing method for dropping the fine particles from the surface of the catalyst particles is not particularly limited, and specifically, stirring washing or stirring-ultrasound washing may be used. When the catalyst particles are washed with a polar solvent, the catalyst particles and the suspended particles are suspended with fine particles separated from the surface of the catalyst particles. If left for 20 minutes, the catalyst particles having large particle sizes are precipitated and the fine particles are still polar solvents. Will remain in a suspended state. The microparticles are removed by tilting the filtrate in which these microparticles are suspended. At this time, the catalyst particles having a particle size of less than 10 ㎛ can be removed at the same time can be selected only for the Fischer-Tropsch reaction catalyst having a particle size of 10 ~ 300 ㎛.

According to the method for preparing a catalyst for Fischer-Tropsch reaction according to the present invention, by cleaning the catalyst prepared by the impregnation method with a polar solvent to effectively remove the fine particles of less than 10 ㎛ physically attached to the surface of the catalyst particles in advance Therefore, it is possible to greatly reduce the filter load problem in the product separation process, the agglomeration of the catalyst, and the like during the bubble column slurry reaction. In addition, by removing the fine particles through the washing it is easy to move the product and reactants on the surface of the catalyst can improve the activity of the catalyst.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

[Example]

Example 1

1067 g of gamma-alumina (particle size: 45 to 90 μm (60%), 90 to 150 μm (40%)) as a support, 81 g of phosphoric acid (H ₃ PO ₄ , 85%) and 500 g of deionized water After impregnation, the solvent was removed through a rotary evaporator, dried at 120 ° C., and calcined at 500 ° C. for 5 hours to modify the surface of gamma-alumina. The surface-modified support was impregnated with a solution of 658.9 g of cobalt nitrate (Co (NO ₃ ) ₂ ㅇ 6H ₂ O) in 700 g of ethanol, followed by removal of the solvent through a rotary evaporator, drying at 120 ° C., and at 500 ° C. It was calcined for 5 hours to carry cobalt. The supporting process of cobalt was repeated twice. Subsequently, a solution of 6.67 g of ruthenium nitrosilnitrate (Ru (NO) (NO ₃ ) ₃ ) dissolved in 450 g of deionized water was impregnated into the support, followed by removal of the solvent through a rotary evaporator, and drying at 120 ° C., and 400 ° C. The catalyst was prepared by firing at 5 hours.

500 g of the prepared catalyst and 2 L of ethanol were mixed in a 5 L beaker, placed in a container of an ultrasonic cleaner (Daihan Scientific, 200 W, 40 kHz), and subjected to ultrasonic washing for 20 minutes while stirring with a stirrer to obtain a fine particle of less than 10 μm adhered to the surface of the catalyst. The particles were dropped. The catalyst particles and the fine particles are suspended in ethanol, and if left for 20 minutes, the catalyst particles having a size of about 10 to 300 μm are precipitated, but the fine particles are still suspended. The floating filtrate was discarded, 1 L of ethanol was added to the catalyst slurry remaining in the beaker, stirred and left to stand for 20 minutes. Then, the filtrate was discarded and the catalyst slurry in which the fine particles were removed was filtered to remove ethanol and dried, thereby preparing a catalyst for Fischer-Tropsch reaction in which the fine particles were removed. Catalyst particles from which fine particles were removed were dried at 120 ° C. and weighed. The fine particles were collected using a high speed centrifuge at 4000 Hz, dried and weighed. The weights of the catalyst particles and the microparticles are shown in Table 1 below.

Example 2

The same procedure as in Example 1 was carried out, but stirring was performed for 20 minutes instead of stirring-ultrasonic washing.

Example 3

In the same manner as in Example 1, deionized water was used instead of ethanol as a polar solvent for washing.

Example 4

After impregnating a solution containing 77.1 g of zirconium nitrate (ZrO (NO ₃ ) ₂ ) and 600 g of deionized water in 500 g of silica gel (Fuji Q15, 150 to 250 μm, spherical), the solvent was removed through a rotary evaporator. After drying at 120 ℃ and calcined at 500 ℃ for 5 hours to modify the surface of the silica gel. The surface-modified support was impregnated with a solution of 358.5 g of cobalt nitrate (Co (NO ₃ ) ₂ ㅇ H ₂ O) in 550 g of ethanol, followed by removal of the solvent through a rotary evaporator, drying at 120 ° C., and at 500 ° C. It was calcined for 5 hours to carry cobalt. The supporting process of cobalt was repeated twice. Then, a solution of 48.73 g of platinum diamine dinitrito (Pt (NH ₃ ) ₂ (NO ₂ ) ₂ ) dissolved in 450 g of deionized water was impregnated into the support, followed by removal of the solvent through a rotary evaporator, and drying at 120 ° C., The catalyst was prepared by baking at 400 ° C. for 5 hours.

After the catalyst washing process is the same as in Example 1.

Comparative Example 1

The same process as in Example 1, but the washing step of the catalyst was omitted.

Comparative Example 2

In the same manner as in Example 4, but the washing step of the catalyst was omitted.

Experimental Example: Slurry Reaction Experiment of Catalyst

The catalysts prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were reduced with hydrogen at 400 ° C. for 12 hours and then sealed and introduced into the slurry reactor. As a reaction medium used in the slurry reactor, 300 mL of squalane was used, and 5 g of the catalyst was injected, followed by reduction treatment at 220 ° C. for 12 hours or more in the reactor. Reaction conditions are the reaction temperature 220 ~ 240 ℃, reaction pressure 20 kg / ㎠, space velocity 2000 L / kg _cat ㅇ hr ^-1 and stirring speed is 2000 rpm reactant carbon monoxide: hydrogen: carbon dioxide: argon (internal standard) Fischer-Tropsch reaction was carried out by injection into the reactor at a molar ratio of 28.4: 57.3: 9.3: 5. The Fischer-Tropsch reaction on the slurry reactor was reacted for 120 hours at 220 ° C., followed by an additional 120 hours at 240 ° C., and reacted for a total of 240 hours to observe agglomeration of the catalyst. The content of the product obtained by the reaction is summarized in the following Table 1, the results of which used an average value of 10 hours in the region where the activity of the catalyst is stabilized and maintained.

division Separation rate of particles by washing with water (%) Reaction test result After reaction
Catalytic agglomeration
Generation amount (g) Particle size
10 ~ 300 ㎛ Particle size
Less than 10 ㎛ Reaction temperature
(℃) CO conversion rate
(%) Selectivity (mol% of carbon)
C1 / C2 ~ C4 / C5 or above Example 1 97.1 2.9 220 42.7 2.9 / 3.8 / 93.3 0.21 240 75.2 3.4 / 4.7 / 91.9 Example 2 97.6 2.4 220 41.6 2.7 / 3.6 / 93.7 0.31 240 74.3 3.3 / 4.6 / 92.1 Example 3 96.5 3.5 220 42.1 2.9 / 4.7 / 92.4 0.17 240 76.5 3.6 / 4.9 / 91.5 Example 4 95.4 4.6 220 38.4 4.9 / 5.6 / 89.5 0.36 240 65.3 5.2 / 6.7 / 88.1 Comparative Example 1 No separation process 220 37.5 5.2 / 6.6 / 88.2 1.41 240 63.4 6.2 / 7.8 / 86.0 Comparative Example 2 No separation process 220 26.8 6.4 / 7.6 / 86.0 1.75 240 48.2 7.6 / 8.9 / 83.5

As shown in Table 1, the catalysts of Examples 1 to 4 in which microparticles of less than 10 μm were removed by washing were significantly improved in catalyst aggregation than those of Comparative Examples 1 and 2, which were not washed. In addition, the carbon monoxide conversion rate and the selectivity of the product having a carbon number of 5 or more is high, but the selectivity of methane is low, it can be seen that the effect of improving the catalytic activity.

1 is a scanning electron micrograph of the catalyst particles prepared in Example 1 and Comparative Example 1, the surface (d) of the catalyst particles, the cleaning process is omitted, the fine particles are physically attached a large amount, but the result of washing with a polar solvent It can be seen that these fine particles were removed to clean the catalyst particle surface (b). Therefore, it can be seen that the washing method proposed in the present invention is simple and efficient in removing microparticles.

As a result, according to the Fischer-Tropsch reaction catalyst production method of the present invention, it is possible to prepare a catalyst from which fine particles of less than 10 μm that cause filter load, catalyst agglomeration, etc., generated in a bubble column slurry reactor are possible. By removing these fine particles in advance it was confirmed that there is an effect to enhance the catalytic activity.

Claims (6)

Impregnating the support with a modifier precursor solution followed by drying and firing to modify the surface of the support;
Impregnating a cobalt precursor solution on the surface-modified support, followed by drying and firing to support cobalt;
Preparing a catalyst by impregnating a cobalt-supported support with a promoter precursor solution, followed by drying and calcining;
Washing the catalyst with a polar solvent to prepare a turbid solution in which catalyst particles and fine particles less than 10 μm separated from the surface of the catalyst particles are suspended; And
Depositing the catalyst particles in the turbid solution, and removing the fine particles by inclining the filtrate in which the fine particles are suspended;
Fischer-Tropsch reaction method for producing a catalyst comprising a.
The method of claim 1, wherein the polar solvent is at least one selected from deionized water, methanol, ethanol, propanol and butanol.
The method of claim 1, wherein the Fischer-Tropsch reaction catalyst has a particle size of 10 ~ 300 ㎛.
According to claim 1, wherein the cobalt precursor is a nitrate, acetate salt of cobalt or a mixture thereof, the enhancer is at least one selected from platinum, ruthenium and rhenium, the enhancer precursor is an oxide, acetate, nitrate or the like of the enhancer Method for producing a catalyst for Fischer-Tropsch reaction, characterized in that the mixture
The fischer according to claim 1, wherein the support is alumina, the modifier is at least one selected from phosphorus, silicon, lanthanum and boron, and the modifier precursor is an oxide, acetate, nitrate, or a mixture thereof. -Preparation of the catalyst for the Tropsch reaction.
The method according to claim 1, wherein the support is silica, the modifier is at least one selected from aluminum, zirconium and phosphorus, and the modifier precursor is an oxide, acetate, nitrate or a mixture thereof of the modifier. Method for preparing a catalyst for the Ropsch reaction.

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