KR20140109224A - catalyst for fischer tropsh synthesis supported in pores of ordered mesoporous carbon and preparation method of the same - Google Patents

Abstract

The present invention relates to a catalyst for fischer tropsch synthesis containing mesoporous carbon materials in a regular structure of which an average diameter of mesopores is nanoscale; and metal-containing catalyst particles of which an average inner size of the mesoporous carbon materials is nanoscale. The catalyst for fischer tropsch synthesis features that a cross sectional area of the metal-containing catalyst particles inside mesopore takes 85-95% of a cross sectional area of the mesopore when the metal-containing catalyst particles are metallic oxides, and a cross sectional area of the metal-containing catalyst particles inside mesopore takes 65-95% of a cross sectional area of the mesopore when the metal-containing catalyst particles are reduced metals. The catalyst for fischer tropsch synthesis according to the present invention improves productivity in synthesizing reaction of fischer tropsch manufacturing synthetic oil from synthetic gas as utilization of the catalyst becomes maximized because nanosize metal catalyst particles are supported with high dispersivity in mesoporous carbon materials, which are supporters, and natural performance of the catalyst is manifested to the fullest because interaction with the supporters becomes minimized.

Description

[0001] The present invention relates to a catalyst for synthesis of Fischer-Trops supported on a porous carbon material, and a catalyst for fischer trops synthesis supported on pores of ordered mesoporous carbon and preparation method of the same,

TECHNICAL FIELD The present invention relates to a catalyst for synthesizing Fischer-Tropsch on which porous nano-sized metal-containing catalyst particles are supported on a porous carbon material having a regular structure, and a method for producing the same.

One of the main goals of the petrochemical process is to optimize the composition of the reaction catalyst, the composition of the reactants, the temperature and the pressure to produce petrochemical products with high conversion and selectivity. In this case, metal catalysts such as iron, cobalt, molybdenum, tungsten, bismuth, nickel and copper are often used as the reaction catalyst, and noble metal catalysts such as rhodium, gold, platinum, ruthenium and rhenium may be used. Such a metal catalyst is dispersed and supported on the surface of a support such as alumina, silica, titania, etc., and is mainly used. If necessary, a noble metal such as platinum or palladium may be used as a cocatalyst

These catalysts are mainly of alumina γ-Al _{(2 O 3, a-Al} 2 O 3 Etc.), silica (SiO ₂ ), titania (TiO ₂ ), magnesia (MgO), carbon and the like. Generally, incipient wetness method and impregnation method are mainly used for such a support. For example, the Fischer-Tropsch synthesis reaction catalyst may be prepared by dissolving a salt of Pt, Ru, Re or the like used as a catalyst precursor cobaltate (Co (NO ₃ ) ₂ .H ₂ O and the like) as a cocatalyst in an appropriate solvent, Is impregnated into the pores of the support, and dried, and the desired amount of catalyst material is supported. Thereafter, the dried catalyst is calcined in air or an inert gas atmosphere to obtain catalyst particles in the form of metal oxide crystals supported on a support.

However, such a conventional method does not uniformly obtain the size or shape of the crystal of the catalyst, and the activity or selectivity may be significantly deteriorated due to the interaction between the metal catalyst crystal and the support.

It is an object of the present invention to provide a method for improving the performance of a catalyst for Fischer-Tropsch synthesis, in which a uniform nano-scale size capable of exerting a confinement effect on the pores of a regularly structured porous carbon material support having an average diameter of mesopores of nanoscale Of catalyst particles.

Another object of the present invention is to provide a porous carbonaceous material support having a regular structure in which the mean diameter of the mesopore is nanoscale and having a size capable of exhibiting a constraining effect in a pore without forming metal- And a method for producing a catalyst for Fischer-Tropsch synthesis containing metal-containing catalyst particles.

A first aspect of the present invention relates to a porous carbon material having a regular structure in which mesopores have an average diameter of nanoscale; And metal-containing catalyst particles supported on the pores of the porous carbon material and having an average size of nanoscale, wherein when the metal-containing catalyst particles are metal oxides, When the cross-sectional area of the catalyst particles accounts for 85% to 95% of the mesopore cross-sectional area, and when the metal-containing catalyst particles are a reduced metal, the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 65% to 95% And a catalyst for synthesis of Fischer-Tropsch.

A second aspect of the present invention is a method for preparing a porous carbon material comprising the steps of: 1) impregnating a porous carbon material support having a regular structure in which mesopores have an average diameter of nanoscale, a catalyst precursor solution; 2) drying the impregnated support; 3) repeating steps 1) and 2) until the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 85% to 95% of the mesopore cross-sectional area; And 4) calcining the dried support. The present invention also provides a method for producing a catalyst for Fischer-Tropsch synthesis according to the first aspect of the present invention.

In the third aspect of the present invention, in the porous carbon material support having a regular structure in which the mean diameter of mesopore cross-section is nanoscale, the metal-containing catalyst particles are not formed on the outer surface having no pore confinement effect, 1. A method for producing a catalyst for Fischer-Tropsch synthesis comprising metal-containing catalyst particles having a size capable of exhibiting a restraining effect, comprising the steps of: 1) impregnating the porous carbon material support with a catalyst precursor solution; 2) drying the impregnated support; 3) repeating steps 1) and 2) until the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 85% to 95% of the mesopore cross-sectional area; And (4) calcining the dried support. In step (1), (i) a porous carbon material support not subjected to a hydrophilic treatment is used so that the catalyst precursor solution is not impregnated on the outer surface, or (ii) Characterized in that a porous carbon material support is used which has been subjected to a hydrophilic treatment only to such an extent that the catalyst precursor solution is not impregnated on the outer surface of the porous carbon material support.

A fourth aspect of the present invention provides a catalyst for Fischer-Tropsch synthesis prepared according to the production method of the third aspect.

A fourth aspect of the present invention is a method for producing a liquid hydrocarbon from a syngas using a Fischer-Tropsch synthesis reaction, comprising the steps of: a catalyst for Fischer-Tropsch synthesis of the first aspect or a Fischer- (Ii) a step (i) of applying a catalyst for the synthesis of Tropsch to a Fischer-Tropsch synthesis reactor, (ii) a step of reducing the catalyst to activate it as a catalyst for Fischer-Tropsch synthesis, and And iii) carrying out a Fischer-Tropsch synthesis reaction by the Fischer-Tropsch synthesis reaction.

Hereinafter, the present invention will be described in detail.

The porous carbon material support having a regular structure such as CMK-3 has an expanded pore structure such as a nanochannel, so that when the catalyst nanoparticles are supported in the pores, they can serve as a nanocarbon reactor. The present invention provides a catalyst for the synthesis of Fischer-Tropsch with excellent performance by utilizing the pore-restraining effect and the hydrophobic property of a porous carbon material support having a regular pore structure of nanoscale.

The carbon material is known to be somewhat inert to the catalytically active material. Strong interactions between the catalyst material and the support material can oxidize the metal, which loses the activity and selectivity of the catalyst.

The carbon support can enhance the performance of the catalyst for Fischer-Tropsch synthesis, facilitate the desorption of by-product water, disperse the heat of reaction, and aid in dispersing the catalyst nanoparticles due to the high surface area (FIG. 10) The number of active sites can be increased. In particular, ordered mesoporous carbons (OMCs) have a higher specific surface area, well-developed interconnected pores, and a smaller pore size than other porous carbons such as activated carbon and graphite great.

In order to minimize the interaction between the catalyst and the support, the present invention uses a porous carbon material as a support and repeats the impregnation and drying of the catalyst precursor solution in the pores (mesopore) of the porous carbon material support with a regular structure twice or more, Containing catalyst particles in the pores of the porous carbon material are formed to have the same or similar nano size, i.e., uniform nano size, in the pores of the porous carbon material, and the particle size of the metal-containing catalyst particles in the pores is grown .

Even when the metal-containing catalyst particles having a smaller size are formed in the pores of the regular porous carbon material having a mesopore average diameter of nanoscale, the metal-containing catalyst particles in the form of metal oxide must be grown to a size larger than the pore cross- , Metal-containing catalyst particles reduced in metal volume and reduced in size from the metal oxide are maintained at a predetermined size or more, and the metal-containing catalyst particles are not agglomeration or sintering due to the pore-constraining effect. In the case of the Fischer- And its performance against water produced as a by-product (Fig. 8). That is, the metal-containing catalyst particles which do not have a certain size or more with respect to the pore cross-sectional area are oxidized or sintered by the reaction heat of extreme reaction and the water produced as a byproduct during the Fischer-Tropsch reaction.

When the metal-containing catalyst particles are metal oxides, it is preferable that the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 85% to 95%, preferably 90% to 95% of the mesopore cross-sectional area.

When the metal-containing catalyst particles are a reduced metal, the cross-sectional area of the metal-containing catalyst particles in the mesophore ranges from 65% to 95%, preferably 70% to 95%, more preferably 80% 95%, and still more preferably 85% to 90%.

According to the present invention, if the metal-containing catalyst particles as metal oxide occupy 65% to 95% of the pore cross sectional area in the porous carbon material support having a regular structure such as CMK-3, even if the metal oxide is reduced, A nanocrystal reactor structure is maintained, and crystals are not sintered after FT synthesis (FIG. 11).

In the present invention, the metal-containing catalyst particles may have a metal content of 15 wt% or more, preferably 20 wt% or more, and preferably 50 wt% or less, based on 100 wt% of the catalyst for Fischer-Tropsch synthesis.

On the other hand, the present inventors have found that a porous carbonaceous material support having a regular structure in which the average diameter of pores (mesopores) are nanoscale is small in chemical interaction and has no pore-restraining effect on the outer surface of the porous carbonaceous material support, The catalyst crystals supported on the outer surface of the catalyst are very vulnerable to agglomeration or sintering and it has been found that the metal catalyst crystals may fall off the support due to carbon deposition during the FT synthesis reaction in severe cases. On the basis of these discoveries, the present invention is characterized in that the catalyst containing metal-containing catalyst particles having a size capable of exhibiting a pore-restraining effect in the pores, and that the metal-containing catalyst particles are hardly formed on the outer surface of the porous carbon material support, It is another feature to provide a catalyst for use.

Therefore, the catalyst for Fischer-Tropsch synthesis according to the present invention mainly contains metal-containing catalyst particles in the pores of a porous carbonaceous material support having a regular structure in which the average diameter of pores (mesopores) is nanoscale, ≪ / RTI > is minimized and can have a high degree of dispersion. The degree of dispersion of the metal crystal measured by the X-ray diffraction method may be 15% or more, and more preferably 25% or more. When the metal-containing catalyst particles are supported on an existing alumina support or the like, the crystal size of the metal oxide is not constant, irregular shapes are formed, and the particles are not uniformly dispersed.

In particular, the catalyst for Fischer-Tropsch synthesis according to the present invention is characterized in that, when the catalyst precursor solution is impregnated into the porous carbon material support, the catalyst precursor solution is impregnated into the porous carbon material support (i) , Or (ii) a porous carbon material support having a hydrophilic treatment on the outer surface of the porous carbon material support to such an extent that the catalyst precursor solution is not chemically impregnated is used, whereby porosity weakening effect of agglomeration or sintering The metal-containing catalyst particles may hardly be formed on the outer surface of the carbon material support.

In the present invention, the fact that the metal-containing catalyst particles are not formed on the outer surface of the porous carbon material support means that the metal-containing catalyst particles are not substantially formed, Containing catalyst particles are formed on the outer surface of the porous carbonaceous material support as long as the degree of dispersion of the metal crystal measured by the porous carbonaceous material support can be maintained at 15% or more, preferably 25% or more, It can be considered that the catalyst particles are not formed.

In the present invention, the metal-containing catalyst particles may be in a metal oxide form or in a reduced metal form.

 The metal-containing catalyst particles may be at least one selected from the group consisting of Co, Ni, Cu, Fe, Zn, Ru, Mo, W, (Rh), palladium (Pd), silver (Ag), platinum (Pt), and combinations thereof.

In the present invention, the metal-containing catalyst particles preferably have an average size of 5 nm or less. The size of the metal-containing catalyst particles is the same as or similar to the pore size of the porous carbon material, and the metal-containing catalyst particles in the form of metal oxide are reduced to metal particles, for example, 70 to 90% Can be. According to previous studies, the appropriate size of catalyst crystals in terms of catalytic activity is about 6-8 nm, and catalysts with metal crystals of less than 6 nm generally have low C ₅₊ selectivity and high methane selectivity, and Fischer-Tropsch synthesis It is known that H ₂ O by-products cause reoxidation of small Co ⁰ nanoparticles and that reoxidized CoO nanoparticles are difficult to reduce. However, the catalytic activity of 20 Co / CMK-3 of Example 2 remained almost constant after 20 hours in the steady state, which means that no re-oxidation occurred (FIG. 8).

The porous carbon material may be a mesoporous carbon material. The porous material is divided into microporous and mesoporous materials depending on the pore size. Typically, when the pore size is 2 nm or less, micropores and when the pore size is between 2 and 50 nm, . The porous carbon material of the present invention is not limited to the pore size, but is preferably a mesoporous carbon material for the production of nano-sized metal particles. The pore size of the mesoporous carbon material is preferably less than 10 nm.

In the present invention, the porous material may be carbon nanotubes, CMK-3, CMK-8, MSU-F-C, activated carbon, graphite fiber, activated carbon fiber or a mixture thereof. The porous carbon material having a regular structure used in the present invention may have a uniform array of linear pore structures. Further, it is preferable that the pores are connected to improve the mass transfer performance.

As shown in FIG. 1, CMK-3 has a regular channel, the average pore size is about 4 nm, and the Brunauer.Emmett.Teller (BET) surface area is about 1500 m ² g ^-1 . In CMK-3, the channel-shaped pore structure is formed by interconnected carbon rods, with open slits on the sides of these carbon rods.

The porous carbon material used in the present invention is prepared by: a) filling a carbon precursor, which is a saccharide, a hydrocarbon, or an alcohol, into pores of mesoporous silica and firing; b) dissolving the resultant material of step a) in a silica structure using an acidic or basic material; c) immersing the resultant material of step b) in an acidic material, followed by treatment and drying.

The saccharide is a compound which is relatively small in the carbohydrate and is soluble in water to give a sweet taste. Sugars include glucose, fructose, galactose, glucose, sucrose, and the like. In the present invention, the carbon precursor may be glucose, sucrose, furfuryl alcohol, or the like, but is not limited thereto.

SBA-15, SBA-3, MSU-H, MCM-41, KIT-6, MCM-48, SBA-16 and MSU-F are examples of the mesoporous silica materials used in step a) , But is not limited thereto. Any silica material having a regular microporous structure can be used. The SBA-15, SBA-3, MSU-H and MCM-41 all have a structure in which a bundle of long cylinders is gathered, and then a carbon precursor is impregnated into the inside of the cylinder.

The impregnation of the carbon precursor into the mesoporous silica in step a) may be performed by repeating impregnation and drying after making the carbon precursor into an aqueous solution. At this time, the carbon precursor is prepared into an aqueous solution and impregnated, and an aqueous acid catalyst such as sulfuric acid may be added to the aqueous solution. Impregnation and drying are repeated until the carbon precursor is sufficiently impregnated, and when drying is completed, the silica-carbon composite can be completed by calcination.

In step b), the silica is removed from the silica-carbon composite due to the acidic or basic substance, leaving only the carbon structure. The carbon support of the regular structure thus produced has a structure of silica and a replica structure, so that it has a surface area equal to that of the mesoporous silica used, and the space filled with silica becomes pores.

A non-limiting example of an acidic material is HF, and a non-limiting example of a basic material is NaOH.

The step c) is a step of treating the resultant material of the step b) with an acidic substance and drying the resultant. In this case, the acidic substance may be a strong acidic solution such as nitric acid, sulfuric acid, hydrochloric acid, etc., and is used in the form of an aqueous solution, and the concentration is preferably 0.01 to 1 M. Typically, a nitric acid aqueous solution can be used. This treatment can be carried out by immersing the support in an acidic aqueous solution at room temperature, through which the support is more easily impregnated with the catalyst precursor.

Meanwhile, the method for producing a catalyst for Fischer-Tropsch synthesis according to the present invention comprises

1) impregnating a porous carbonaceous material support having a mesopore average diameter of nanoscale with a catalyst precursor solution;

2) drying the impregnated support;

3) repeating steps 1) and 2) until the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 85% to 95% of the mesopore cross-sectional area; And

4) firing the dried support.

The pores in the porous carbonaceous material support may be in the form of nanocrystals, and in step 1), the impregnation of the catalyst precursor solution into the pores of the nanocrystalline type may result in capillary forces or nanocrystal pressure reduction or physical force (e.g., sonication) Lt; / RTI >

In step 1), (i) a non-hydrophilic porous carbonaceous material support is used to prevent impregnation of the catalyst precursor solution on the outer surface, or (ii) a chemical impregnation of the catalyst precursor solution on the outer surface of the porous carbonaceous material support It is preferable to use a hydrophobic porous carbon material support. As a result, the metal-containing catalyst particles are hardly formed on the outer surface of the porous carbon material support having no pore-restraining effect. A non-limiting example of the hydrophilic treatment of (ii) is to treat the porous carbon material support with a strong acid aqueous solution of 0.01 M to 1 M. For example, treating a porous carbon material support with a 1 M aqueous nitric acid solution forms a small amount of hydrophilic functional groups sufficient to allow the catalyst precursor solution to be impregnated within the mesopores, but most of the surface remains hydrophobic.

The catalyst precursor may be selected from the group consisting of Co, Ni, Cu, Fe, Zn, Ru, Mo, T, Bi, Containing precursor may be a metal-containing precursor containing at least one metal selected from the group consisting of Re, Rh, Pd, Ag and Pt, Oxides of metal, Hydroxides, Chloride salts, Carbonates, Acetates, Citrates, Nitrosyl nitrates, Nitrates. Firefighting. Oxalate, carboxylate, sulfate and the like, alkoxy precursors containing hydrocarbons as oil-soluble precursors. Ammonium precursors, and the like.

The impregnation can be carried out by incipient wetness impregnation, making the catalyst precursor solution. At this time, water or an alcohol may be used as a solvent of the catalyst precursor solution. The incipient wetness impregnation is the most widely used impregnation method, and it is manufactured by impregnating impregnation solution corresponding to the pore volume of the catalyst support, and the method is simple.

Since the volume of the pores is limited at the time of impregnation, the impregnation can be repeated twice or three times until the impregnation is sufficiently performed, and the impregnation is subjected to a drying process. When the impregnation is performed, the capillary force is utilized as much as possible. In the case where the impregnation is not performed well, the support may be used after vacuum treatment, or a method of performing sonication at the time of impregnation may be used.

The drying in step 2) may be carried out at 110 to 150 ° C for 5 to 24 hours.

The above steps 1) and 2) are repeated until the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 85% to 95% of the mesopore cross-sectional area, Repeat until the content is at least 20% by weight.

Step 4) of calcining the dried support may be carried out in an inert gas atmosphere such as nitrogen, helium, argon, and the like. Through the calcination, metal-containing catalyst particles having a size similar to or slightly smaller than the mesoporous pore size are produced. Since the catalyst particles are confined within a regular mesoporous structure, the growth of the catalyst particles is suppressed due to the constraining effect of the support, and a uniform and uniform size distribution is produced. In one embodiment, the size of the catalyst was about 4 nm and the degree of dispersion was 30.1%.

Further, the present invention provides a method for producing liquid hydrocarbons from syngas using a Fischer-Tropsch synthesis reaction, comprising the steps of: i) subjecting the Fischer-Tropsch synthesis catalyst according to the present invention to a Fischer- Applying to the reactor; ii) reducing and activating the catalyst; And iii) performing the Fischer-Tropsch synthesis reaction with the activated Fischer-Tropsch synthesis catalyst.

The method for producing liquid hydrocarbons according to the present invention may prepare a synthesis gas (CO / H ₂ ) by reforming natural gas at least before step iii).

On the other hand, the Fischer-Tropsch synthesis reactor may be a fixed bed, fluidized bed or slurry reactor.

In the present invention, the step ii) is a step of reducing the catalyst for Fischer-Tropsch synthesis. In the reduction process, the metal oxide-type catalyst particles may be reduced to metal and the particle size thereof may be reduced to, for example, 75%, thereby inhibiting migration and diffusion of reactants or products during the Fischer-Tropsch synthesis reaction .

The Fischer-Tropsch synthesis reaction is preferably carried out while maintaining the hydrogen / carbon monoxide reaction ratio at 1.5 to 2.5 molar ratio. iii) steps from 200 to 350 ℃, a reaction pressure of 5 to 30kg / cm ^3, a space velocity of 1000 may be performed at ^{1 -} 10000 h.

In addition, the method for producing liquid hydrocarbons according to the present invention may further comprise a step of reforming the Fischer-Tropsch synthesis reaction product after step iii).

As described above, when the Fischer-Tropsch synthesis catalyst is used for the Fischer-Tropsch synthesis reaction, the catalyst of the present invention exhibits a high degree of dispersion, and the Fischer- The carbon monoxide conversion and the liquid hydrocarbon selectivity of the synthesis reaction increase.

The nano-sized catalyst prepared by the process of the present invention maximizes the utilization of the catalyst due to its high dispersion and minimizes the interaction with the support, thereby maximizing the performance of the catalyst. Thus, the productivity of the Fischer- .

FIG. 1 shows the results (a) and (b) of the measurement of the pore size of ordered mesoporous carbon (OMC) prepared according to Example 1. FIG.
FIG. 2 is a conceptual view of a nano-channel reactor according to one embodiment of the present invention. FIG. 2 is a schematic view (a) of producing a synthetic petroleum gas from a syngas in a nanochannel reactor, a view (b) A TEM image (c) showing the cobalt oxide nanoparticles confined in the extended pores, and enlarged views (d) and (e) thereof.
FIGS. 2 (b) to 2 (e) show that the average pore size is about 4 nm and the CoO crystals are uniformly distributed in the mesopores of CMK-3.
Figures 3 (a) and 3 (b) show HR TEM images of the catalyst prepared according to Example 2. 3 (c) shows the EDX mapping of cobalt, oxygen and carbon (cobalt: purple, oxygen: green, carbon: yellow), and FIGS. 3 (D) (d) is an elemental analysis image of cobalt, (e) is oxygen, and (f) is carbon.
3 (a) and 3 (b) show that the Co nanoparticles are uniformly spaced at equal intervals in each mesopore.
FIG. 4 shows XRD analysis data of catalysts (10 Co / CMK-3, 15 Co / CMK-3, 20 Co / CMK-3) having different weights of cobalt according to Comparative Examples 1 and 2, respectively. As can be seen from FIGS. 3 (c) to (f) and FIG. 4, the distribution of the element Co is similar to the distribution of the element O, and most of the nanoparticles are present as CoO.
5 shows the results of measurement of the TPR (temperature programmed reduction) profile (a) and the H ₂ uptake profile (b) for each of the catalysts prepared according to Comparative Example 1 and Example 2. FIG.
6 is a TEM image of a Co / γ-Al ₂ O ₃ catalyst particle supported on an aluminum support prepared according to Comparative Example 2. FIG.
7 shows a TEM image of 20 Co / MSU-FC prepared in Comparative Example 3. Fig.
FIG. 8 shows the results of measuring changes in FT activity with time for each catalyst. 10 Co / CMK-3 and 15 Co / CMK-3, which have much smaller catalyst nanoparticle sizes than mesopores, were gradually deactivated. Small catalyst nanoparticles can easily migrate to the periphery and are sintered due to heat and lack of spatial restriction during FT synthesis.
9 shows SEM images of CMK-3 (a) and MSU-FC (b).
10 shows the pore size distribution and surface area of CMK-3 and MSU-FC.
11 shows TEM images of (a) 20 Co / CMK-3 and (b) 20 Co / MSU-FC after 40 hours of FT synthesis reaction.

Hereinafter, the present invention will be described in more detail with reference to examples. These examples are for further illustrating the present invention, and the scope of the present invention is not limited by these examples.

Example 1: Preparation of an OMC support

A mesoporous silica SBA-15 2g water to 20g AlCl ₃ Was impregnated with an aqueous solution of 0.36 g and Aluminized (AlSBA-15). 1.5 g of furfuryl alcohol was thoroughly rubbed on 1 g of the prepared AlSBA-15, followed by heat treatment at 85 ° C for 4 hours to polymerize furfuryl alcohol. After completion of the polymerization, the mixture was carbonized at 850 DEG C for 2 hours under an Ar gas to complete a silica-carbon composite. After cooling to room temperature, the mesoporous carbon (OMC) support with a regular structure was completed by dissolving the silica skeleton using HF or an aqueous solution of sodium hydroxide. The results of measuring the pore size distribution of the OMC thus obtained are shown in FIG. 1A, and TEM images are shown in FIG. 1B. The obtained OMC has a surface area of about 1500 m ² / g, a pore size of about 4 nm, and the arrangement of linear pore structures is very uniform. The carbon material prepared using SBA-15 as a template is also referred to as CMK-3.

Example 2: Preparation of OMC-supported cobalt catalyst

OMC (CMK-3) prepared in Preparation Example 1 was treated with a 1 M nitric acid aqueous solution for about 30 minutes at room temperature. After washing and drying, the cobalt nitrate precursor was made into an ethanol solution so as to be about 20 wt% of the cobalt catalyst particles, and impregnated into the OMC pores by the incipient wetness impregnation method. Since the volume of the pores is limited, the impregnation process is carried out two or three times, and each impregnation is subjected to a drying process. In case of impregnation, the capillary force is utilized to the maximum. In the case where the impregnation does not work well, the OMC support is subjected to a vacuum treatment or a sonication at the time of impregnation. The dried catalyst was calcined in a nitrogen atmosphere at 400 ° C for 5 hours to produce cobalt oxide crystals having a size similar to or slightly smaller than the mesoporous pore size. The prepared cobalt oxide crystals are shown in Fig. An elemental analysis image of the produced cobalt catalyst is shown in FIG. From this, it can be seen that the cobalt oxide crystals are produced to a very constant size, and the arrangement is also very orderly due to the influence of OMC pores. The size of the obtained cobalt oxide crystals was about 4 nm, which was similar to the pore size. References RD Jones, CH Bartholomew, Appl. Catal. 1988, 39, 77-88, the% Dispersion (% dispersion degree = 96.2 / cobalt crystal size) was determined to be 30.1%. During the Fischer-Tropsch synthesis reaction, the catalyst is activated by reducing the cobalt oxide to cobalt metal, which is reduced to about 75%. Therefore, the catalyst prepared in this Example does not significantly inhibit the migration and diffusion of the reactants or products, and this is confirmed by the performance verification of the catalyst afterwards.

Comparative Example 1: Preparation of cobalt catalyst supported on CMK-3 with a cobalt content of less than 20 wt%

A CMK-3 supported catalyst containing 10 wt% and 15 wt% of cobalt was prepared in the same manner as in Example 2, except that the weight content of cobalt metal in the final catalyst particle was less than 20 wt%. CMK-3 supported catalyst containing 10 wt% of cobalt metal was named 10 Co / CMK-3, and CMK-3 supported catalyst containing 15 wt% was named 15 Co / CMK-3.

XRD data of 10 Co / CMK-3, 15 Co / CMK-3 and 20 Co / CMK-3 catalysts of the above Examples and Comparative Examples are shown in FIG. As a result, it was confirmed that as the content of cobalt increased, the width of the main peak near 45 ° became narrower and became sharper. This means that the FWHM (full width at half maximum) calculated at the main peak is shorter and the size of the catalyst crystal is larger (ALPatterson, Phys. Rev., 1939, 56,978). That is, it was confirmed that the size of the 20 Co / CMK-3 cobalt oxide crystal is larger than the size of the cobalt oxide crystal of 10 Co / CMK-3 and 15 Co / CMK-3.

The temperature programmed reduction (TPR) profile and the H ₂ uptake profile of each catalyst were measured and are shown in FIG. As a result, a reduction peak at a low temperature appeared at 150 ° C to 350 ° C, a reduction peak at a high temperature appeared at 350 ° C to 900 ° C, and an increase in the amount of H ₂ uptake was observed at a high cobalt loading. When the reduction profile was divided into two parts, the peak in the low temperature region increased while the peak in the high temperature region decreased when the cobalt loading was large. This is because, when the cobalt loading is large, the interaction between the support and the catalyst material is weakened and the reducing property is increased.

Comparative Example  2: Preparation of cobalt-based catalyst using alumina support (20 Co / γ- Al ₂ O ₃ )

The cobalt precursor was supported on a gamma-alumina support to prepare a cobalt-based catalyst. The used gamma-alumina was alumina having a pore volume of 0.5 ml / g, a pore size of 9-10 nm and a surface area of about 170 m ² / g as measured by the BET method.

Gamma - after the determination of the weight of the nitrates of cobalt precursor to cobalt metal from about 20 wt% supported on an alumina support prepared by the solution of a Co / γ-Al ₂ O ₃ forms to (the solvent is an alcohol, water and the like), impregnation Catalyst particles were prepared. A TEM image of the prepared catalyst particles is shown in Fig. According to the XRD analysis, the average size of the cobalt oxide crystals in the prepared catalyst particles is about 14.4 nm, but the crystal size of the cobalt oxide, which is shown in black in the TEM image of FIG. 5, is not constant. Also, it was confirmed that the shape is also irregularly obtained.

Also, while the pore size of the support used was 9-10 nm, the size of the oxide crystals formed was about 14.4 nm, which was larger than the pore size. This means that the metal oxide crystals were not produced only in the pores of the support but also outside the pores. This can be confirmed also in the TEM image of FIG. 6, which shows that the crystals are formed in the form of agglomerated or agglomerated on the alumina support surface. References R. D. Jones, C. H. Bartholomew, Appl. Catal. 1988, 39, 77-88. The percent dispersion was 8.9%.

20Co / γ-Al ₂ O ₃ was also sintered to a certain extent during reduction, and the metal crystal particle size before reduction was 10.8 nm, which was increased to 16.0 nm after reduction.

Comparative Example 3: Preparation of cobalt catalyst supported on MSU-F-C

A cobalt catalyst was prepared (20 Co / MSU-FC) in the same manner as in Example 2 except that MSU-FC was used as the porous carbon material. MSU-FC is a mesocellular porous carbon material synthesized from mesoporous silica "MSU-F-silica" and having small pores of 4 to 8 nm between large pores of about 30 nm and pore structure. The TEM image of the 20 Co / MSU-FC prepared above is shown in FIG. The CoO crystal size at 20 Co / MSU-FC was 8.7 nm. At 20 Co / MSU-FC, the nanoparticles are much smaller than the larger pores, so the confinement effect is insignificant. Due to the weak constraining effect and the inert nature of the carbon, the cobalt nanocrystals interact very poorly with the carbon support, and the weak constraining effect and the inert nature of the carbon occur agglomeration or sintering of the nanoparticles during catalyst preparation or FT synthesis.

Comparative Example 4: Preparation of cobalt-based catalyst with alumina support and co-catalyst added (0.05 Pt -23 Co / γ- Al ₂ O ₃ )

A catalyst was prepared in the same manner as in Comparative Example 2 except that 0.05 wt% of Pt was contained as a cocatalyst component and the content of cobalt was 23 wt%.

Example  3: Catalyst performance test

Table 1 below shows the sizes of the catalysts prepared in Example 2, Comparative Examples 2 and 3.

Catalyst
Measured from XRD
Particle Size (nm) Co ⁰
Particle Size (nm) % Dispersion
96.2 / d (Co ⁰⁾ Example 2 OMC catalyst (20 Co / CMK-3) 4.0 (CoO) 3.2 30.1 Comparative Example 2 Alumina supported catalyst
_{(20Co / γ-Al 2 O} 3) 8.7 (CoO) 7.0 11.1 Comparative Example 3 20 Co / MSU-F-C 14.4 (Co ₃ O ₄ ) 10.8 8.9

Further, in order to compare the performances of the catalysts of the above-described Examples and Comparative Examples 1 to 4, Fischer-Tropsch synthesis reaction was carried out using the above catalyst. The reaction conditions were as follows: Syngas space velocity (GHSV) = 4000 ml / g-cat / h, temperature (T) = 220 캜, pressure (P) = 2.0 MPa, H ₂ / CO ratio = H ₂ / CO / CO ₂ / Ar) = 57.3 / 28.4 / 9.3 / 5.0 (mol%). The result of the Fischer-Trops synthesis reaction is shown in Table 2 below.

Catalyst
CO conversion rate
(%) FT activity
_{^{(10 -5 mol CO g Co -1}} s -1) Selectivity (%) CH ₄ C ₅₊ Example 2 OMC catalyst (20 Co / CMK-3) 81.3 5.73 2.7 93.6 Comparative Example 1 OMC catalyst (15 Co / CMK-3) 48.1 3.83 10.3 80.8 Comparative Example 1 OMC catalyst (10 Co / CMK-3) 35.5 4.94 10.8 82.1 Comparative Example 2 Alumina supported catalyst
_{(20Co / γ-Al 2 O} 3) 54.9 3.86 4.7 90.3 Comparative Example 3 20 Co / MSU-F-C 24.4 1.72 5.4 89.5 Comparative Example 4 _{0.05Pt-23Co / γ-Al 2} O 3 62.9 3.85 4.3 90.9

As can be seen from the above Table 2, CO conversion than 20 Co / CMK-3 catalyst, the catalyst content of the catalyst did not have this (15 Co / CMK-3, 10 Co / CMK-3) of the present invention, C _{5 +} Selectivity and productivity (FT activity) were higher. This is because if the crystal size of the catalytic metal does not grow to a certain size, the metal crystals are easily oxidized or sintered by the reaction heat and the water produced as a by-product during the reaction.

As shown in Table 2, the 20 Co / CMK-3 catalyst (Example 2) has a higher CO conversion and C _{5 +} selectivity than 20 Co / γ-Al ₂ O ₃ (Comparative Example 2).

In addition, the catalyst having a content of less than 20% of the catalyst is lower in conversion and selectivity than the conventional alumina supported catalyst (20 Co / γ-Al ₂ O ₃ ). However, since the amount of cobalt added is smaller than that of 20 Co / γ-Al ₂ O ₃ , the value of FT activity for calculating the production amount of cobalt metal added to the 10 Co / CMK-3 and 15 Co / CMK- high.

However, the 20 Co / CMK-3 of the present invention is superior in all aspects such as conversion rate, C ₅₊ selectivity, and productivity (FT activity) compared with conventional alumina supported catalysts, / CMK-3, 10 Co / CMK-3). In addition, it was confirmed that the conversion was superior to the alumina supported catalyst in which the cocatalyst was further added, and the performance was superior to that of the catalyst supported on MSU-FC.

Example 4: Measurement of catalytic activity over time

FT activity was measured in the same manner as in Example 3, and FT activity over time was measured. The result is shown in FIG. As a result, 20 Co / CMK-3 of the present invention showed the best FT activity and remained stable after 35 hours, indicating that reoxidation did not occur. However, the catalyst with a low metal content of the catalyst was not stabilized (15 Co / CMK-3, 10 Co / CMK-3), and it was confirmed that the FT activity was reduced by the reoxidation or sintering as the reaction time became longer.

Claims (17)

A porous carbon material having a regular structure in which mesopores have an average diameter of nanoscale; And metal-containing catalyst particles supported on the pores of the porous carbon material and having an average size of nanoscale,
When the metal-containing catalyst particles are metal oxides, the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 85% to 95% of the mesopore cross-
Wherein when the metal-containing catalyst particles are a reduced metal, the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 65% to 95% of the mesopore cross-sectional area.
The catalyst for synthesis of Fischer-Tropsch according to claim 1, wherein the metal-containing catalyst particles are supported at a metal content of 20 wt% or more based on 100 wt% of the catalyst for Fischer-Tropsch synthesis.
The catalyst for Fischer-Tropsch synthesis according to claim 1, wherein the metal-containing catalyst particles have an average particle diameter of 5 nm or less.
The catalyst according to claim 1, wherein the porous carbon material having a regular structure is uniform in the arrangement of the linear pore structure.
The method of claim 1, wherein the metal-containing catalyst particles are selected from the group consisting of Co, Ni, Cu, Fe, Zr, Ru, Mo, ), Bismuth (Bi), rhenium (Re), rhodium (Rh), palladium (Pd), silver (Ag), platinum (Pt), and combinations thereof. catalyst.
The catalyst for Fischer-Tropsch synthesis according to claim 1, wherein the metal-containing catalyst particles are not present on the outer surface of the porous carbon material support, and the dispersion degree of the metal crystal measured by the X-ray diffraction method is 15% or more.
The method of claim 1, wherein the porous carbon material comprises
a) filling a pore of a mesoporous silica with a carbon precursor, which is a saccharide, a hydrocarbon, or an alcohol, and calcining;
b) dissolving the resultant material of step a) in a silica structure using an acidic or basic material;
c) immersing the resultant material of step b) in an acidic material, followed by treatment and drying;
Lt; RTI ID = 0.0 > of: < / RTI >
The catalyst according to claim 7, wherein the acidic substance used in step c) is a strongly acidic aqueous solution having a concentration of 0.01M to 1M.
The catalyst according to claim 1, wherein the porous carbon material is CMK-3.
1) impregnating a porous precursor porous porous material support having a mesopore average diameter of nanoscale with a catalyst precursor solution;
2) drying the impregnated support;
3) repeating steps 1) and 2) until the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 85% to 95% of the mesopore cross-sectional area; And
4) firing the dried support
10. The method for producing a catalyst for synthesis of a Fischer-Tropsch according to any one of claims 1 to 9.
The method of claim 10, wherein in step (1), a porous carbon material support not subjected to hydrophilicity treatment is used so that the catalyst precursor solution is not impregnated on the outer surface, or (ii) A porous carbon material support having a hydrophilic treatment only to the extent that the precursor solution is not impregnated is used,
Thereby producing a catalyst for Fischer-Tropsch synthesis in which no metal-containing catalyst particles are formed on the outer surface of the porous carbon material support having no pore confinement effect.
In a porous carbon material support having a regular structure in which the mesopores have an average diameter of nanoscale, a metal-containing catalyst particle is not formed on the outer surface having no pore confinement effect, A method for producing a catalyst for synthesis of Fischer-Tropsch containing metal-containing catalyst particles,
1) impregnating the porous carbon material support with a catalyst precursor solution;
2) drying the impregnated support;
3) repeating steps 1) and 2) until the cross-sectional area of the metal-containing catalyst particles in the mesopore accounts for 85% to 95% of the mesopore cross-sectional area; And
4) firing the dried support,
In step 1), (i) a non-hydrophilic porous carbonaceous material support is used to prevent impregnation of the catalyst precursor solution on the outer surface, or (ii) the catalyst precursor solution is not impregnated on the outer surface of the porous carbonaceous material support Wherein the porous carbon material support is subjected to a hydrophilic treatment only to the extent that the porous carbon material support is not used.
13. The method of claim 12, wherein the pores in the porous carbonaceous material support form nano channels,
Wherein in step 1) the impregnation of the catalyst precursor solution in the pores of the nanocrystalline type is carried out through a capillary force of the nanocouple or a reduced pressure or physical force in the nanocannon.
13. The method of claim 12, wherein the hydrophilic treatment of (ii) comprises treating the porous carbon material support with a strong acid aqueous solution of 0.01M to 1M.
14. A catalyst for synthesis of Fischer-Tropsch produced by the production method of any one of claims 12 to 14.
A method of producing liquid hydrocarbons from syngas using a Fischer-Tropsch synthesis reaction,
(i) A process for producing a catalyst for Fischer-Tropsch synthesis according to any one of claims 1 to 9 or a process for producing a Fischer-Tropsch synthesis catalyst produced by the process according to any one of claims 12 to 14, Applying to the reactor;
ii) reducing and activating the catalyst; And
iii) performing the Fischer-Tropsch synthesis reaction with the activated Fischer-Tropsch synthesis catalyst.
17. The method of claim 16, iii) steps from 200 to 350 ℃, a reaction pressure of 5 to 30kg / cm ^3, a space velocity of 1000 - a method is performed at ^{1 -} 10000 h.

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