Cobalt-based catalyst for fischer-tropsch synthesis reaction and method for preparing same

Abstract

The present invention relates to a cobalt-based shaped catalyst for a Fischer-Tropsch synthesis reaction and a method for preparing same and, more specifically, to a method for preparing a cobalt-based shaped catalyst for a Fischer-Tropsch synthesis reaction and to a cobalt-based shaped catalyst for a Fischer-Tropsch synthesis reaction prepared by the preparation method, wherein the catalyst can produce a synthetic liquid fuel having a carbon number of 5 or more without an upgrading process by increasing the activity of the Fischer-Tropsch synthesis reaction while simultaneously promoting an isomerization reaction and a cracking reaction.

Description

Cobalt-based catalyst for Fischer-Tropsch synthesis reaction and method for preparing the same

[0001] The present invention relates to a cobalt-based catalyst for Fischer-Tropsch synthesis reaction and a method for producing the same, and more particularly, to a method for producing a cobalt-based catalyst for Fischer-Tropsch synthesis reaction, which increases the activity of Fischer-Tropsch synthesis reaction and simultaneously promotes isomerization reaction and cracking reaction, thereby enabling the production of a synthetic liquid fuel having a carbon number of 5 or more without an upgrading process, and a cobalt-based catalyst for Fischer-Tropsch synthesis reaction produced by the method.

[0002] The Fischer-Tropsch synthesis reaction is a catalytic chemical reaction that uses synthesis gas (CO + H2) derived primarily from natural gas, coal, and biomass to produce a hydrocarbon mixture. As dependence on conventional resources decreases and crude oil prices soar, demand for unconventional gas resources such as landfill gas, associated gas, and remote gas is increasing, leading to a growing demand for clean fuels derived from these sources.

[0003] Recently, the exponential discovery of shale gas reserves around the world and the resulting abundance of reserves and potential for future utilization have led to the development of the Fischer-Tropsch technology, a method of producing clean liquid fuel using synthetic gas derived from gas resources.

[0004] The Fischer-Tropsch synthesis reaction occurs in three phases: gaseous reactants undergo carbon chain growth on the surface of a solid catalyst, and liquid hydrocarbon products are produced. Because this reaction is highly exothermic, when the catalyst is packed in a fixed-bed reactor, extreme heat is generated in the catalyst bed. To control this exotherm, a diluent with excellent thermal stability is mixed in.

[0005] Catalysts (FT catalysts) used in these Fischer-Tropsch synthesis reactions can be broadly divided into iron-based catalysts and cobalt-based catalysts, and both types of catalysts are manufactured by adding small amounts of precious metals such as Pt and Pd to control the conversion rate of carbon monoxide and the selectivity of the product.

[0006] Iron-based catalysts are used in the Fischer-Tropsch synthesis reaction at relatively high temperatures (300°C to 450°C), and the products are diverse, ranging from chemical industry raw materials such as light olefins and alpha olefins to liquid fuels in the gasoline range, and oxygenated compounds such as alcohols, aldehydes, and ketones. Thus, Fischer-Tropsch synthesis using iron-based catalysts has the advantage of obtaining various products at once, but it also entails the disadvantage of requiring a subsequent separation process to obtain the desired compound.

[0007] Meanwhile, cobalt-based catalysts are used at relatively low temperatures (220°C to 300°C) because they produce a high methane yield when used in high-temperature Fischer-Tropsch synthesis reactions. Cobalt-based catalysts primarily produce linear paraffins with 8 to 25 carbon atoms, and their selectivity for these hydrocarbon products is high. However, the linear paraffins produced are in a waxy state at room temperature, and must be converted to gasoline, aviation fuel, and diesel-based hydrocarbons through a subsequent upgrading process in order to be used as liquid fuel.

[0008] The upgrading process involves cracking or isomerizing linear paraffins using amorphous silica-alumina or crystalline zeolites with strong acid sites to shorten the carbon chain or to produce olefins and isoparaffins, creating liquid fuels that remain fluid even at room temperature. Because this subsequent upgrading process incurs additional costs, various methods have been attempted to omit it and produce liquid fuels in one step using the Fischer-Tropsch synthesis reaction.

[0009] In the prior art, U.S. Patent No. 5,104,902, a method for producing liquid hydrocarbons by synthesizing ZSM-5 zeolites with different crystal sizes and using them as supports to produce a cobalt catalyst is proposed, and in U.S. Patent No. 7,943,674, a method for producing liquid hydrocarbons using a cobalt catalyst using zeolite Y and ZSM-12 as supports is proposed, since the prior art ZSM-5 zeolite shows high methane selectivity and low C10 or higher hydrocarbon selectivity. However, the zeolite supports used in the above prior arts have small pore sizes and surface areas, making it difficult to effectively support a large amount of cobalt nanoparticles, so that the CO conversion rate per catalyst content is lower than that of the prior art Al2O3 or SiO2, and there is a disadvantage in that the yield of hydrocarbons is reduced.

[0010] Additionally, a typical method for imparting mesopores to zeolite involves a post-treatment method, as described in U.S. Patent No. 9,120,090, which selectively dissolves silicon in the zeolite support using an alkaline solution. However, this method suffers from the disadvantage of being uneconomical, as it results in a loss of at least 10 wt% and up to 80 wt% of the zeolite support itself.

[0011] Therefore, there is a need to develop a cobalt-based catalyst that can produce a highly fluid synthetic liquid fuel without an upgrading process by forming it with a cobalt catalyst without losing the acid sites of the zeolite itself, thereby maintaining the activity of the Fischer-Tropsch synthesis reaction and promoting the isomerization reaction and cracking reaction.

[0012] [Prior Art Literature]

[0013] [Patent Document]

[0014] (Patent Document 1) U.S. Patent No. 5,104,902 (Registration Date: April 14, 1992)

[0015] (Patent Document 2) U.S. Patent No. 7,943,674 (Published: May 26, 2011)

[0016] (Patent Document 3) U.S. Patent No. 9,120,090 (Published: July 12, 2012)

[0017] The main purpose of the present invention is to solve the above-described problems, and to provide a method for producing a cobalt-based catalyst for Fischer-Tropsch synthesis reaction that increases the activity of Fischer-Tropsch synthesis reaction and simultaneously promotes isomerization reaction and cracking reaction, thereby selectively producing C5 or higher hydrocarbons without an upgrading process.

[0018] In addition, an object of the present invention is to provide a cobalt-based catalyst for Fischer-Tropsch synthesis reaction, which is manufactured by the above manufacturing method and can selectively manufacture C5 or higher hydrocarbons from synthesis gas.

[0019] In addition, an object of the present invention is to provide a method for selectively producing C5 or higher hydrocarbons from synthesis gas using a cobalt-based catalyst produced by the above production method.

[0020] In order to achieve the above object, one embodiment of the present invention provides a method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction that selectively produces C5 or higher hydrocarbons from synthesis gas, the method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction comprising the steps of: (a) supporting a cobalt precursor on a catalyst support to obtain a first mixture; (b) drying the obtained first mixture; (c) supporting a cocatalyst precursor on the dried first mixture to obtain a second mixture; (d) drying and heat-treating the obtained second mixture; (e) mixing a zeolite and an inorganic binder with the heat-treated second mixture to obtain a third mixture; And (f) a step of drying and calcining the third mixture obtained above; and the zeolite of step (e) is characterized in that the SiO2 / Al2O3 molar ratio is 30 or more, and a method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction is provided.

[0021] In a preferred embodiment of the present invention, the catalyst carrier may be characterized by being at least one selected from the group consisting of alumina, zirconia, silica, mullite, silicon carbide, titanium carbide, titanium oxide, titanium diboride, yttria, silicon nitride, titanium nitride, tungsten carbide, and boron carbide.

[0022] In a preferred embodiment of the present invention, step (a) may be characterized by loading the cobalt precursor so that 5 to 40 wt% of cobalt is loaded based on the total weight of the heat-treated second mixture.

[0023] In a preferred embodiment of the present invention, the co-catalyst precursor may be characterized as being a precursor of at least one metal selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), and rhenium (Re).

[0024] In a preferred embodiment of the present invention, the step (c) may be characterized by loading the cocatalyst precursor so that 0.001 wt% to 2 wt% of the cocatalyst is loaded based on the total weight of the heat-treated second mixture.

[0025] In a preferred embodiment of the present invention, the heat treatment in step (d) may be performed at 300°C to 500°C.

[0026] In a preferred embodiment of the present invention, the step (e) may be characterized by mixing 50 to 400 parts by weight of zeolite and 50 to 400 parts by weight of inorganic binder with 100 parts by weight of the second mixture.

[0027] In a preferred embodiment of the present invention, the inorganic binder may be selected from the group consisting of silica sol, clay, and aluminum hydroxide sol.

[0028] In a preferred embodiment of the present invention, the calcination in step (f) may be performed at 300°C to 500°C.

[0029] Another embodiment of the present invention provides a cobalt-based catalyst for Fischer-Tropsch synthesis reaction that selectively produces C5 or higher hydrocarbons from synthesis gas, characterized in that it is produced by the above-described production method.

[0030] Another embodiment of the present invention provides a method for selectively producing C5 or higher hydrocarbons from synthesis gas, characterized in that a cobalt-based catalyst produced by the above-described production method is introduced into a reactor, and then synthesis gas is injected to perform a Fischer-Tropsch synthesis reaction.

[0031] In another preferred embodiment of the present invention, the synthesis gas has a space velocity of 2,000 mlg cat -1 hr -1 ~ 20,000 mlg cat -1 hr -1 It can be characterized in that the reaction is injected into the reactor within the range, and the synthesis reaction is carried out at a reaction temperature of 200 ℃ to 300 ℃ and a reaction pressure of 10 bar to 40 bar.

[0032] The method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction according to the present invention comprises hybridizing a cobalt-based catalyst supported with a cocatalyst and a zeolite having a specific SiO2 / Al2O3 molar ratio using an inorganic binder, and then drying and calcining the catalyst to thereby increase the activity of the Fischer-Tropsch synthesis reaction and simultaneously promote the isomerization reaction and cracking reaction, thereby selectively producing C5 or higher hydrocarbons from synthesis gas without an upgrading process.

[0033] FIG. 1 is an image schematically illustrating a catalyst layer according to one embodiment of the present invention.

[0034] Figure 2 is a graph showing the results of measuring the CO conversion rate (a) and the (olefin C5+ iso-paraffin C5) / (normal-paraffin C5) ratio (b) and the log (area ratio) (c) according to the carbon number according to the reaction time measured in Example 11 and Comparative Example 7 of the present invention.

[0035] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined solely by the scope of the claims.

[0036] In describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description is omitted.

[0037] In the specification, when "includes," "has," "consists of," and "consists of" are used, other parts may be added unless "only" is used. When a component is expressed in the singular, it includes the plural unless otherwise explicitly stated.

[0038] The present invention provides, in one aspect, a method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction that selectively produces C5 or higher hydrocarbons from synthesis gas, comprising the steps of: (a) supporting a cobalt precursor on a catalyst support to obtain a first mixture; (b) drying the first mixture thus obtained; (c) supporting a cocatalyst precursor on the dried first mixture to obtain a second mixture; (d) drying and heat-treating the second mixture thus obtained; (e) mixing a zeolite and an inorganic binder with the heat-treated second mixture to obtain a third mixture; and (f) drying and calcining the third mixture thus obtained; wherein the zeolite of step (e) has a SiO2 / Al2O3 molar ratio of 30 or more.

[0039] Hereinafter, the present invention will be described in detail.

[0040] The method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction according to the present invention first comprises: supporting a cobalt precursor on a catalyst carrier to obtain a first mixture [step (a)].

[0041] The above catalyst support can be used without limitation as long as it is a support component having an acid site according to the distribution of the desired hydrocarbon product in the Fischer-Tropsch synthesis reaction, and for example, it can be at least one selected from the group consisting of alumina, zirconia, silica, mullite, silicon carbide, titanium carbide, titanium oxide, titanium diboride, yttria, silicon nitride, titanium nitride, tungsten carbide, and boron carbide, and preferably, it can be alumina having good compatibility with the inorganic binder described below.

[0042] The catalyst carrier according to the present invention is a porous material containing many pores, so that the cobalt precursor, which is a catalytically active component, can be supported within the pores to effectively improve reactivity. A material that can sufficiently support the catalytically active component, is not reactive with the catalytically active component, and is not sensitive to temperature changes can be selected.

[0043] The above catalyst carrier is in the form of a powder that is pulverized or manufactured by a conventional method, and may have an average particle size of 1 ㎛ to 500 ㎛, preferably 10 ㎛ to 200 ㎛. If the average particle size of the catalyst carrier is less than 1 ㎛, the mechanical properties of the catalyst may deteriorate, and at the same time, the pore size may be small, so that the loading rate of the catalytically active component may decrease. If it exceeds 500 ㎛, the surface area may decrease, which may lower the reactivity due to a decrease in the effectiveness factor of the catalytically active component.

[0044] Meanwhile, cobalt precursors can be used without limitation as long as they are cobalt (Co) precursors of catalytically active components applicable to the Fischer-Tropsch synthesis reaction, and water-soluble precursors include, but are not limited to, oxides, oxyhydroxides, chlorides, carbonates, acetates, citrates, nitrosilnitrates, nitrates, hydroxides, oxalates, carboxylates, sulfates, and fat-soluble precursors such as alkoxy precursors containing hydrocarbons, ammonium precursors, etc.

[0045] At this time, cobalt (Co) in the cobalt precursor may be included in the cobalt precursor so that it can be supported in an amount of 5 wt% to 40 wt%, preferably 5 wt% to 30 wt%, based on the total weight of the heat-treated second mixture described below. If the cobalt of the cobalt (Co) precursor is supported in an amount of less than 5 wt% based on the total weight of the heat-treated second mixture, the cobalt content supported on the catalyst carrier may be too small, which may lower the activity of the reaction, and if it exceeds 40 wt%, the cobalt content supported on the catalyst carrier may be too large, which may cause some of the cobalt to be leached out without being completely supported on the catalyst carrier during the catalyst manufacturing process, and at the same time, the interaction between the catalyst carrier and the cobalt may be weakened, which may cause sintering between cobalt particles during the catalytic reaction.

[0046] The support of the above cobalt precursor can be applied without limitation as long as it is a method capable of supporting the cobalt precursor on a catalyst carrier, and examples thereof include a hydrothermal synthesis method, a co-precipitation method, an impregnation method, a mechanical mixing method, a deposition method, etc., and preferably, an impregnation method, etc.

[0047] In one embodiment, the impregnation among the above-mentioned supporting methods may be performed by dissolving a cobalt precursor in a solvent, dividing the impregnation into several steps to evenly disperse the cobalt precursor dissolved in the solvent on the catalyst carrier, and performing the impregnation at 20 to 50° C. for 1 to 12 hours. At this time, the solvent may be any solvent that can evenly disperse the cobalt precursor, and may be, for example, a polar solvent such as water, methanol, ethanol, propanol, butanol, or acetone. The content thereof may be used without limitation as long as it can evenly disperse the cobalt precursor, and may be, for example, 100 to 500 parts by weight based on 100 parts by weight of the cobalt precursor.

[0048] Thereafter, the obtained first mixture is dried, and a co-catalyst precursor is loaded onto the dried first mixture to obtain a second mixture [steps (b) and (c)].

[0049] Drying of the above first mixture can be performed at 100°C to 250°C for a predetermined period of time, for example, 1 hour to 12 hours, and can be performed using a conventional method such as hot air, constant temperature and humidity, or microwave.

[0050] If the above drying temperature is less than 100°C, the solvent used in the catalyst production may not evaporate smoothly within the pores of the catalyst carrier, which may cause cobalt agglomeration during the calcination process described later. If it exceeds 250°C, rapid desorption of the solvent within the pores of the catalyst carrier may cause cobalt component agglomeration.

[0051] The above dried first mixture may support a co-catalyst precursor to improve the activity and stability of the catalyst. As the co-catalyst precursor, any precursor of at least one metal selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), and rhenium (Re) may be used without limitation, and the precursor may be a salt compound or complex containing these metal atoms, and specifically, may be at least one selected from nitrates, sulfates, phosphoric acids, halogen salts, alkoxide salts, oxynitrates, oxalates, acetate salts, alkyl salts, hydrates thereof, and the like.

[0052] At this time, the cocatalyst among the cocatalyst precursors is included so that it can be supported at 0.001 wt% to 0.5 wt%, preferably 0.005 wt% to 0.1 wt%, based on the total weight of the heat-treated second mixture. If it is added at less than 0.001 wt%, there may be a problem that the effect of improving the reducibility of cobalt metal is minimal, and if it exceeds 0.5 wt%, there is a disadvantage in that it is disadvantageous in terms of the reducibility of cobalt metal and the price of the catalyst.

[0053] The method for supporting the above-mentioned co-catalyst precursor can be applied without limitation as long as it is a method capable of supporting the co-catalyst precursor in the first mixture, and examples thereof include a hydrothermal synthesis method, a co-precipitation method, an impregnation method, a mechanical mixing method, a deposition method, etc., and preferably, an impregnation method, etc.

[0054] In one embodiment, the impregnation among the above-mentioned supporting methods may be performed by dissolving a co-catalyst precursor in a solvent, dividing the solvent into several stages, and evenly dispersing the co-catalyst precursor dissolved in the solvent on the catalyst carrier, and performing wet impregnation at 20 to 50° C. for 1 to 12 hours. At this time, the solvent may be any solvent that can evenly disperse the co-catalyst precursor, and may be, for example, a polar solvent such as water, methanol, ethanol, propanol, butanol, or acetone. The content thereof may be used without limitation as long as it can evenly disperse the co-catalyst precursor, and may be, for example, 100 to 500 parts by weight based on 100 parts by weight of the co-catalyst precursor.

[0055] Next, the second mixture containing the above-mentioned co-catalyst precursor is subjected to drying and heat treatment [step (d)].

[0056] Drying of the above second mixture can be performed at 100°C to 250°C for a predetermined period of time, for example, 1 hour to 12 hours, and can be performed by a conventional method such as an oven, hot air, constant temperature and humidity, or microwave.

[0057] If the above drying temperature is less than 100°C, the solvent used in the catalyst production may not evaporate smoothly within the pores of the catalyst carrier, which may cause cobalt and cocatalyst agglomeration during the calcination process described later. If it exceeds 250°C, rapid desorption of the solvent within the pores of the catalyst carrier may cause cobalt and cocatalyst components agglomeration.

[0058] The heat treatment of the above-described dried second mixture can be varied in consideration of the unique glass transition temperature depending on the type of catalyst support, but in order to obtain a catalyst for Fischer-Tropsch synthesis reaction having high CO conversion rate and selectivity for hydrocarbons having a carbon number of C5 or more without catalyst cracking, it can be preferably heat-treated at 300 to 500°C for a predetermined time in an oxidizing atmosphere containing oxygen, air, etc. The heat treatment time can vary depending on conditions such as the calcination temperature, the amount supported, the size and amount of the catalyst support, and the like, but can be, for example, 1 to 24 hours.

[0059] If the heat treatment temperature is less than 300°C, appropriate interaction between cobalt, which is a catalytically active component, and the catalyst carrier may not be formed, resulting in particle growth during the reaction. In addition, if the temperature exceeds 500°C, the particles of the cobalt component may increase, reducing dispersibility, and cobalt silicate or cobalt aluminate may be formed, resulting in a decrease in the CO conversion rate and the selectivity for hydrocarbons with a carbon number of C5 or higher. Therefore, it is necessary to maintain the heat treatment range described above.

[0060] In addition, during the heat treatment process, rapid temperature changes can cause rapid evaporation and oxidation of the solvent, resulting in cracks and pores, which significantly reduce the strength. Therefore, it is desirable to manufacture the product by gradually increasing the temperature by 10℃ or less per minute.

[0061] Afterwards, the heat-treated second mixture is sequentially mixed with zeolite and an inorganic binder to obtain a third mixture [step (e)].

[0062] The above zeolite, when mixed in an appropriate ratio with a catalyst containing cobalt, promotes isomerization and cracking reactions to shorten the carbon number, or selectively obtains liquid fuel that is fluid even at room temperature by producing olefins and isoparaffins.

[0063] At this time, the content of the zeolite may be mixed in an amount of 50 to 400 parts by weight, preferably 50 to 300 parts by weight, based on 100 parts by weight of the heat-treated second mixture. If the content of the zeolite is less than 50 parts by weight based on 100 parts by weight of the second mixture, the isomerization reaction and cracking reaction effects of the zeolite may be insufficient, so that some wax may be generated in the product, and if it is mixed in an excessive amount exceeding 400 parts by weight, the volume of the catalyst may increase, so that the production efficiency per volume of the catalyst may decrease.

[0064] In addition, among the various zeolites, the zeolite having a SiO2 / Al2O3 molar ratio of 30 or more, preferably 30 to 280, more preferably 40 to 150, and even more preferably 50 to 90, is most suitable in terms of having an appropriate number of Bronsted acid sites with hydrocarbon isomerization and cracking performance, and in particular, the ZSM-5 series known to have good acid catalyst properties can be used.

[0065] When the SiO2 / Al2O3 molar ratio of the above zeolite is less than 30, the Brønsted acid site having the ability to isomerize and crack hydrocarbons in the zeolite is insufficient, which may cause a problem in that the wax is not sufficiently converted.

[0066] Meanwhile, the inorganic binder binds the heat-treated second mixture and the zeolite to each other to provide cohesion and viscosity, and can be mixed in an amount of 50 to 400 parts by weight per 100 parts by weight of the heat-treated second mixture. If the inorganic binder is mixed in an amount of less than 50 parts by weight per 100 parts by weight of the second mixture, the strength of the catalyst may decrease and wear may occur during the reaction, and if it exceeds 400 parts by weight per 100 parts by weight of the second mixture, the ratio of the catalytically active component in the catalyst may be low, which may be disadvantageous in terms of catalytic activity.

[0067] The above inorganic binder may be silica sol; clay such as bentonite, kaolin, and attapulgite; aluminum hydroxide sol such as boehmite; etc., and preferably, a silica sol having properties suitable for acidity can be used. In particular, the silica sol used as the above inorganic binder has excellent zeolite binding properties and thermal / structural properties, and thus can improve the mechanical properties of the catalyst without adding an organic binder or other inorganic binders other than the silica sol and without a photocuring agent.

[0068] Meanwhile, the third mixture of zeolite and inorganic binder may further include a step of forming a molded catalyst by forming it into a predetermined shape in a step before drying and calcination described below.

[0069] At this time, the above molding can be performed by applying a molding method, device, and conditions typically used in the manufacture of a molded catalyst, and for example, extrusion molding can be performed.

[0070] Thereafter, the third mixture in which the zeolite and the inorganic binder are sequentially mixed is dried and calcined to manufacture a catalyst [step (f)].

[0071] At this time, the drying of the third mixture can be performed at 10°C to 250°C for a predetermined period of time, for example, 1 hour to 12 hours, and can be dried using a conventional method such as an oven, hot air, constant temperature and humidity, or microwave.

[0072] If the above drying temperature is less than 10°C, the solvent used in the catalyst production may not evaporate smoothly within the pores of the catalyst carrier, which may cause cobalt or cocatalyst agglomeration during the calcination process described later. If it exceeds 250°C, rapid moisture evaporation may interfere with the formation of a uniformly shaped catalyst. Therefore, it is desirable to maintain the above temperature range.

[0073] The calcination of the above-mentioned dried third mixture can be performed to enhance the inherent strength and hardness of the catalyst carrier.

[0074] The calcination of the above-described dried third mixture can be varied in consideration of the unique glass transition temperature depending on the type of catalyst support, but in order to obtain a catalyst for Fischer-Tropsch synthesis reaction with high CO conversion rate and selectivity for hydrocarbons having a carbon number of C5 or higher without catalyst cracking, it can be preferably calcined at 300°C to 500°C for a predetermined period of time in an air atmosphere. The calcination time may vary depending on conditions such as the calcination temperature, the amount supported, the size and amount of the catalyst support, and the like, but may be, for example, 1 hour to 24 hours.

[0075] If the above-mentioned calcination temperature is less than 300℃, an appropriate interaction between cobalt and the carrier is not formed, which may cause particles to grow larger during the reaction. In addition, if it exceeds 500℃, the particles of the cobalt component increase, which reduces dispersibility, and problems such as the formation of cobalt silicate or cobalt aluminate may occur, which may reduce the CO conversion rate and the selectivity for hydrocarbons with a carbon number of C5 or higher. Therefore, it is necessary to maintain the above-mentioned calcination range.

[0076] In addition, since rapid temperature changes during the firing process cause rapid evaporation and oxidation of the solvent, resulting in cracks and pores, which significantly reduces strength, it is desirable to manufacture the product by gradually increasing the temperature by 10°C or less per minute.

[0077] The present invention provides a cobalt-based catalyst for Fischer-Tropsch synthesis reaction that selectively produces C5 or higher hydrocarbons from synthesis gas, characterized in that it is produced by the aforementioned production method from another perspective.

[0078] The catalyst for Fischer-Tropsch synthesis reaction manufactured as described above exhibits high selectivity for hydrocarbons of C5 or higher, specifically C5 to C20, and thus can be usefully used in Fischer-Tropsch synthesis for manufacturing liquid fuel from synthesis gas.

[0079] The present invention provides a method for selectively producing C5 or higher hydrocarbons from synthesis gas, characterized in that a cobalt-based catalyst produced by the aforementioned production method is introduced into a reactor, and then synthesis gas is injected to perform a Fischer-Tropsch synthesis reaction.

[0080] First, the cobalt-based catalyst manufactured by the aforementioned manufacturing method can be activated before the Fischer-Tropsch synthesis reaction of the synthesis gas. Specifically, the activation step of the cobalt-based catalyst can activate the catalyst by reducing the catalyst at a temperature (250°C to 800°C) at which the catalyst can be reduced under a hydrogen atmosphere (2 to 10% H2). In one embodiment, after mounting the catalyst in a reactor, the catalyst can be reduced by flowing 5% hydrogen (H2) gas at a flow rate of 10 ml / min to 200 ml / min at 250°C to 500°C for 2 to 10 hours. After reducing the catalyst under a hydrogen atmosphere, the reduced catalyst is mounted in the reactor.

[0081] Next, the Fischer-Tropsch synthesis reaction is performed by injecting synthesis gas into the reactor equipped with the catalyst. At this time, the synthesis gas used as a raw material contains hydrogen (H2) and carbon monoxide (CO), and a synthesis gas having a molar ratio of H2 / CO in the range of 0.1 to 4, preferably a H2 / CO molar ratio of 1 to 3, can be used. If the molar ratio of H2 / CO of the synthesis gas is less than 0.1, the carbon deposition rate may increase, shortening the catalyst life, and if the molar ratio of H2 / CO exceeds 4, hydrogenation is promoted, thereby increasing the selectivity of unnecessary methane and short-chain paraffins.

[0082] At this time, the above synthesis gas has a space velocity of 2,000 mlㆍg cat -1 hr -1 ~ 20,000 mlㆍg cat -1 hr -1 , preferably 2,000 mlㆍg cat -1 hr -1 ~ 15,000 mlㆍg cat -1 hr -1 , more preferably 2,000 mlㆍg cat -1 hr -1 , ~ 10,000 mlㆍg cat -1 hr -1 It is preferable to inject into the reactor and react. The space velocity is 2,000 mlㆍg cat -1 hr -1 If it is less than 20,000 mlㆍg, the amount of synthesis gas converted per catalyst is small, which is disadvantageous in terms of the liquid fuel production of the catalyst. cat -1 hr -1 If it exceeds , it is disadvantageous in terms of catalyst conversion rate and liquid fuel yield.

[0083] In addition, the reaction temperature of the Fischer-Tropsch synthesis reaction may be 200 ℃ to 300 ℃, preferably 200 ℃ to 270 ℃, and the chain propagation probability can be increased, so that the carbon of the product can be relatively increased, and when thermodynamics are considered, the production of olefins and iso paraffins is advantageous over the production of paraffins. However, when the reaction temperature is less than 200 ℃, unnecessary high-boiling-point products may be strongly adsorbed to the catalyst, which may rapidly cause selective deactivation, and when the reaction temperature exceeds 300 ℃, the sintering phenomenon of cobalt particles and the carbon deposition rate increase, which not only shortens the life of the catalyst, but also increases the selectivity of methane (C1), which lowers the selectivity of long-chain olefin compounds, which is not preferable.

[0084] According to the present invention, the hydrocarbon produced from the synthesis gas can obtain a liquid fuel containing any one of gasoline, jet fuel or diesel having carbon atoms of C5 to C20.

[0085] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended only to illustrate the present invention and are not intended to limit the present invention.

[0086] <Manufacturing Example 1>

[0087] A cobalt solution was prepared by dissolving 7.6 g of cobalt nitrate hexahydrate [cobalt(Ⅱ) nitrate hexahydrate, Co(NO3)2ㆍ6H2O], a precursor of cobalt, in 5 ml of ethanol (ethyl alcohol, C2H5OH). The cobalt solution was divided into several stages and evenly dispersed in 5 g of alumina (Al2O3) having an average particle size of 50 ㎛, and impregnated at room temperature (24°C) for 1 hour to obtain a first mixture. After the impregnation process was completed, except for the last stage, drying was performed at 250°C for 3 hours. Additionally, 0.25 ml of a platinum solution prepared by dissolving 0.1 g of tetraammineplatinum nitrate [Tetraammineplatinum(II) nitrate, Pt(NH3)4(NO3)2], a platinum precursor, in 10 ml of distilled water (H2O) was impregnated into the dried first mixture at room temperature for 1 hour to obtain a second mixture. Finally, the dried second mixture was heat-treated at 350°C for 5 hours at a heating rate of 2°C / min to prepare a Co-Pt / Al2O3 catalyst. 23 g of the zeolite shown in Table 1 below was mixed with 10 g of the prepared Co-Pt / Al2O3 catalyst, and then 20.6 g of the binder shown in Table 1 below was mixed to obtain a third mixture, which was dried at room temperature for 1 hour and then dried in an oven at 250°C for 4 hours. The third mixture, after drying, was sieved through a sieve with a size of 150 μm. The sieved catalyst was calcined in a calciner at 350°C for 5 hours at a heating rate of 2°C / min to produce a cobalt-based catalyst for the Fischer-Tropsch synthesis reaction.

[0088] <Manufacturing Examples 2 to 5>

[0089] A cobalt-based catalyst for Fischer-Tropsch synthesis reaction was prepared using the same method as in Manufacturing Example 1, but under the conditions of Table 1.

[0090] <Manufacturing Example 6>

[0091] A cobalt solution was prepared by dissolving 7.6 g of cobalt nitrate hexahydrate [cobalt(Ⅱ) nitrate hexahydrate, Co(NO3)2ㆍ6H2O], a precursor of cobalt, in 5 ml of ethanol (ethyl alcohol, C2H5OH). The cobalt solution was divided into several stages and evenly dispersed in 5 g of alumina (Al2O3) having an average particle size of 50 ㎛, and impregnated at room temperature for 1 hour to obtain a first mixture. After the impregnation process was completed, except for the last stage, drying was performed at 250°C for 3 hours. Additionally, 0.1 g of tetraammineplatinum nitrate [Tetraammineplatinum(II) nitrate, Pt(NH3)4(NO3)2], a platinum precursor, was dissolved in 10 ml of distilled water (H2O), and 0.25 ml of a platinum solution was impregnated into the dried first mixture at room temperature for 1 hour to obtain a second mixture. Finally, the dried second mixture was heat-treated at 350°C for 5 hours at a heating rate of 2°C / min to produce a Co-Pt / Al2O3 catalyst.

[0092] <Manufacturing Example 7>

[0093] A cobalt solution was prepared by dissolving 7.6 g of cobalt nitrate hexahydrate [cobalt(Ⅱ) nitrate hexahydrate, Co(NO3)2ㆍ6H2O], a precursor of cobalt, in 5 ml of ethanol (ethyl alcohol, C2H5OH). The cobalt solution was divided into several stages, evenly dispersed in 5 g of alumina (Al2O3), and impregnated at room temperature for 1 hour to obtain a first mixture. After the impregnation process was completed, except for the last stage, drying was performed at 250°C for 3 hours. Additionally, 0.1 g of tetraammineplatinum nitrate [Tetraammineplatinum(II) nitrate, Pt(NH3)4(NO3)2], a platinum precursor, was dissolved in 10 ml of distilled water (H2O), and 0.25 ml of a platinum solution was impregnated into the dried first mixture at room temperature for 1 hour to obtain a second mixture. Finally, the dried second mixture was heat-treated at 350°C for 5 hours at a heating rate of 2°C / min to produce a Co-Pt / Al2O3 catalyst. Next, 0.9 g of the zeolite in Table 1 below was calcined at 550°C (heating condition, 2°C / min) for 5 hours and physically mixed with 0.3 g of the Co-Pt / Al2O3 catalyst using a vortex mixer at 250 rpm for 5 hours to prepare a cobalt-based catalyst for the Fischer-Tropsch synthesis reaction.

[0094] <Manufacturing Examples 8 to 9>

[0095] A cobalt-based catalyst for Fischer-Tropsch synthesis reaction was prepared in the same manner as in Manufacturing Example 8, but the cobalt-based catalyst for Fischer-Tropsch synthesis reaction was prepared under the conditions of Table 1.

[0096] [Table 1]

[0097]

[0098] <Example 1>

[0099] The Fischer-Tropsch synthesis reaction of CO / H2 synthesis gas was performed using the catalyst manufactured in the manufacturing example as shown in Table 2 below at 20 bar, 230 ℃, GHSV = 10,000 mlg cat -1 hr -1 The reaction was performed under the reaction conditions. The reactor used for the reaction experiment was a fixed-bed reactor with an outer diameter of 3 / 8 inch and an inner diameter of 0.74 cm, and glass wool was inserted under the catalyst layer in the reactor to prevent the loss of the catalyst. The reduction of the catalyst was performed for 5 hours at atmospheric pressure and 400°C using a 5% H2 / Ar mixture gas. After the reactor temperature was lowered to 230°C, He was flowed to push out the H2 / Ar mixture gas in the reactor, and the pressure in the reactor was increased to 20 bar. After that, the space velocity was 10,000 mlg cat -1 hr -1 The FTS reaction was carried out by flowing the corresponding synthesis gas (H2 / CO molar ratio = 2), and the product was analyzed through gas chromatography. In the gas analysis using gas chromatography, the FID column used GS-GasPro, and the TCD column used 80 / 100 Porapak Q and 60 / 80 Molecular sieve 5A. CH4, C2H6, C2H4, C3H8, C3H6, iso-C4H 10 , C4H 10 , 1-C4H8, trans-2-C4H8, cis-2-C4H8, iso-C5H 12 and C5H 12 was analyzed, and CO2, Ar, CH4, and CO were analyzed using the TCD column.

[0100] <Examples 2 to 10>

[0101] The Fischer-Tropsch synthesis reaction of synthesis gas was performed in the same manner as in Example 1, but under the conditions of Table 2. Among Examples 2 to 10, Examples 2, 4 to 8, and 10 formed a catalyst layer by mixing a diluent with the catalyst (FT catalyst) manufactured in the manufacturing example at a designated space velocity as shown in Fig. 1, and then filling the reactor, followed by performing the Fischer-Tropsch synthesis reaction.

[0102] <Comparative Examples 1 to 6>

[0103] The Fischer-Tropsch synthesis reaction of synthesis gas was performed in the same manner as in Example 1, but under the conditions of Table 2. Among Comparative Examples 1 to 6, Comparative Examples 1, 2, and 5 formed a catalyst layer by mixing a diluent with the catalyst (FT catalyst) manufactured in the Manufacturing Example at a designated space velocity as shown in Fig. 1, and then filled the reactor, and then the Fischer-Tropsch synthesis reaction was performed.

[0104] [Table 2]

[0105]

[0106] <Experimental Example 1: Evaluation of the Physical Properties of the Catalyst>

[0107] In order to measure the structural characteristics including the pore size of the catalysts manufactured in Manufacturing Examples 3, 4 and 6, N2 isothermal adsorption / desorption experiments were performed using ASAP-2420 from Micrometrics to measure the specific surface area, pore volume and average pore size, and the results are shown in Table 3.

[0108] [Table 3]

[0109]

[0110] As shown in Table 3, it was confirmed that the catalysts of Preparation Examples 3 and 4, in which zeolite was hybridized using an inorganic binder after cobalt loading, had a significantly higher specific surface area than Preparation Example 6, which did not contain zeolite and binder.

[0111] <Experimental Example 2: Catalytic Activity Evaluation>

[0112] 2-1: Catalyst activity evaluation according to catalyst manufacturing method

[0113] In order to evaluate the catalytic activity according to the catalyst preparation method, the CO conversion rate and hydrocarbon selectivity of Example 1, Comparative Example 1, and Comparative Example 4, in which the Fischer-Tropsch synthesis reaction was performed under the same conditions, and the CO conversion rate and hydrocarbon selectivity of Example 3, Comparative Example 1, and Comparative Example 6 were compared, and the results are shown in Tables 4 and 5, respectively. At this time, the (I+O)-C5 / n-C5 ratio in the table is a measurement of the molar ratio of isoparaffin and olefin C5 to normal paraffin C5 measured by gas chromatography, and a high ratio means that the isomerization reactivity on the zeolite catalyst is high, and thus the zeolite performance is high.

[0114] [Table 4]

[0115]

[0116] [Table 5]

[0117]

[0118] As shown in Tables 4 and 5, the catalysts of Preparation Examples 1 and 3, which hybridized zeolites using an inorganic binder after supporting the catalytically active component, showed higher selectivity for carbon atoms of 5 or more (C5+) than the catalysts of Preparation Examples 8 and 9, which physically hybridized zeolites without using an inorganic binder, but showed lower selectivity for methane. Meanwhile, the (I+O)-C5 / n-C5 ratio was higher in the catalysts of Preparation Examples 1, 3, 8, and 9 than in the catalyst of Preparation Example 6, which did not hybridize zeolites. This means that isomerization and cracking reactions of hydrocarbons occur when zeolites are mixed. Among the catalysts mixed with zeolites, it was confirmed that the mixed catalyst after supporting the binder induces isomerization / cracking reactions compared to the FT catalyst, and at the same time, it is advantageous in methane selectivity and C5+ selectivity.

[0119] 2-2: Catalytic activity evaluation according to binder type

[0120] In order to evaluate the catalytic activity according to the type of binder, the CO conversion rate and hydrocarbon selectivity of Examples 2 and 9, in which the Fischer-Tropsch synthesis reaction was performed under the same conditions, were compared and shown in Table 6.

[0121] [Table 6]

[0122]

[0123] As shown in Table 6, the catalyst of Preparation Example 3, which was manufactured using silica sol (SiO2sol) as a binder when mixing zeolites, showed a higher CO conversion rate than the catalyst of Preparation Example 5, which was manufactured using aluminum hydroxide sol (AlOOH sol). This confirms that when silica sol was used as a binder, a molded catalyst having an appropriate size and pore size was manufactured compared to when aluminum hydroxide sol was used as a binder, and thus it was advantageous in terms of the effective factors of the molded catalyst.

[0124] 2-3: Catalytic activity evaluation according to zeolite SiO2 / Al2O3 molar ratio

[0125] In order to evaluate the catalytic activity according to the zeolite SiO2 / Al2O3 molar ratio, the CO conversion and hydrocarbon selectivity of Examples 1 and 3, in which the Fischer-Tropsch synthesis reaction was performed under the same conditions, and the CO conversion and hydrocarbon selectivity of Examples 2, 3, and 10 were compared, and are shown in Tables 7 and 8, respectively.

[0126] [Table 7]

[0127]

[0128] [Table 8]

[0129]

[0130] As shown in Tables 7 and 8, the catalysts of Preparation Examples 3 and 4 using zeolite having a SiO2 / Al2O3 molar ratio of 80 showed high CO conversion and high (I+O)-C5 / n-C5 ratio compared to the catalysts of Preparation Examples 1 and 2 using zeolite having a SiO2 / Al2O3 molar ratio of 30 and the catalyst of Preparation Example 7 using zeolite having a SiO2 / Al2O3 molar ratio of 45, whereas the catalyst of Preparation Example 5 using zeolite having a SiO2 / Al2O3 molar ratio of 280 showed significantly lower CO conversion. Therefore, it was found that it is appropriate to utilize zeolite having a SiO2 / Al2O3 molar ratio of 80, which has appropriate acid properties, in the production of a molded catalyst.

[0131] 2-4: Evaluation of catalyst activity according to space velocity

[0132] In order to evaluate the catalytic activity according to space velocity, the CO conversion rate and hydrocarbon selectivity of Examples 4 to 8, in which the Fischer-Tropsch synthesis reaction was performed under the same conditions and at different space velocities, were compared and are shown in Table 9.

[0133] [Table 9]

[0134]

[0135] As shown in Table 9, it was found that the CO conversion rate and C5+ selectivity increased as the space velocity decreased. As in Examples 7 and 8, when the space velocity was 10,000 mlㆍg cat -1 ㆍhr -1 In these cases, it was confirmed that the (I+O)-C5 / n-C5 ratio significantly decreased. Therefore, it was confirmed that an appropriate space velocity is required for appropriate liquid fuel productivity and zeolite performance efficiency.

[0136] 2-5: Evaluation of catalyst activity according to product yield time

[0137] In order to evaluate the catalytic activity according to the product yield time, the CO conversion and hydrocarbon selectivity of Examples 4 to 8, in which the Fischer-Tropsch synthesis reaction was performed according to the product yield time under the same conditions, are compared and shown in Table 10 and Fig. 2, respectively. At this time, the ASF-alpha (α, alpha) value in Table 10 was determined by quantitatively analyzing each product through FID, and the peak components of each product were determined by calibration using the PNA / PIANO standard kit. After determining the carbon number based on the paraffin peak, the contents of olefins and isoparaffins were analyzed. In addition, the growth probability of the hydrocarbon chain (ASF-alpha value) was calculated by analyzing the contents of each carbon number, and a large ASF-alpha value means that the cracking performance of the zeolite is poor.

[0138] [Table 10]

[0139]

[0140] As shown in Table 10 and FIG. 2, compared to Comparative Example 1 without zeolite, Comparative Example 7 and Example 11 hybridized with zeolite exhibited higher (I+O)-C5 / n-C5 ratios and ASF-alpha values, confirming that the zeolite performs isomerization / cracking. In particular, Example 11 exhibited higher (I+O)-C5 / n-C5 ratios and lower alpha values ​​than Comparative Examples 1 and 7, confirming that it had higher selectivity for C5 to 20 hydrocarbons. In addition, Example 11 exhibited higher CO conversion than Comparative Example 7, confirming that the catalyst prepared through mixing of binders after loading in a hybrid catalyst in which a Fischer-Tropsch catalyst and a zeolite are hybridized exhibited superior catalytic activity and zeolite performance compared to a physically mixed catalyst after loading.

[0141] While the present invention has been described with reference to the above-described embodiments, various embodiments may be constructed within the spirit and scope of the present invention. Accordingly, the scope of the present invention is defined by the appended claims and their equivalents, and is not limited to the specific embodiments described herein.

Claims

1. A method for producing a cobalt-based catalyst for Fischer-Tropsch synthesis reaction that selectively produces C5 or higher hydrocarbons from synthesis gas, The method for producing the above cobalt-based catalyst comprises the steps of (a) obtaining a first mixture by supporting a cobalt precursor on a catalyst carrier; (b) a step of drying the first mixture obtained above; (c) a step of obtaining a second mixture by loading a co-catalyst precursor into the dried first mixture; (d) a step of drying and heat treating the second mixture obtained above; (e) a step of mixing zeolite and an inorganic binder into the heat-treated second mixture to obtain a third mixture; and (f) a step of drying and calcining the third mixture obtained above; A method for producing a cobalt-based catalyst for Fischer-Tropsch synthesis reaction, characterized in that the zeolite of the above step (e) has a SiO2 / Al2O3 molar ratio of 30 or more.

2. In paragraph 1, A method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction, characterized in that the catalyst support is at least one selected from the group consisting of alumina, zirconia, silica, mullite, silicon carbide, titanium carbide, titanium oxide, titanium diboride, yttria, silicon nitride, titanium nitride, tungsten carbide, and boron carbide.

3. In paragraph 1, A method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction, characterized in that the step (a) comprises loading a cobalt precursor so that 5 to 40 wt% of cobalt is loaded based on the total weight of the heat-treated second mixture.

4. In paragraph 1, A method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction, characterized in that the above-mentioned cocatalyst precursor is a precursor of at least one metal selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), and rhenium (Re).

5. In paragraph 1, A method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction, characterized in that the step (c) comprises loading a cocatalyst precursor so that 0.001 wt% to 2 wt% of the cocatalyst is loaded based on the total weight of the heat-treated second mixture.

6. In paragraph 1, A method for producing a cobalt-based catalyst for Fischer-Tropsch synthesis reaction, characterized in that the heat treatment in step (d) is performed at 300°C to 500°C.

7. In paragraph 1, A method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction, characterized in that the step (e) above mixes 50 to 400 parts by weight of zeolite and 50 to 400 parts by weight of an inorganic binder with 100 parts by weight of a heat-treated second mixture.

8. In paragraph 1, A method for producing a cobalt-based catalyst for a Fischer-Tropsch synthesis reaction, characterized in that the above-mentioned inorganic binder is at least one selected from the group consisting of silica sol, clay, and aluminum hydroxide sol.

9. In paragraph 1, A method for producing a cobalt-based catalyst for Fischer-Tropsch synthesis reaction, characterized in that the calcination in the above step (f) is performed at 300°C to 500°C.

10. A cobalt-based catalyst for Fischer-Tropsch synthesis reaction that selectively produces C5 or higher hydrocarbons from synthesis gas, characterized in that it is produced by any one of the production methods of claims 1 to 9.

11. A method for selectively producing C5 or higher hydrocarbons from synthesis gas, characterized in that a cobalt-based catalyst manufactured by any one of the manufacturing methods of clauses 1 to 9 is introduced into a reactor, and then synthesis gas is injected to perform a Fischer-Tropsch synthesis reaction.

12. In paragraph 11, The above synthesis gas has a space velocity of 2,000 mlg cat -1 hr -1 ~ 20,000 mlg cat -1 hr -1 A method for selectively producing C5 or higher hydrocarbons from synthesis gas, characterized in that the synthesis reaction is carried out at a reaction temperature of 200 ℃ to 300 ℃ and a reaction pressure of 10 bar to 40 bar, and the synthesis reaction is injected into the reactor within a range.

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