Method for producing Fischer-Tropsch synthesis catalyst

Abstract

The invention relates to a method for producing a Fischer-Tropsch synthesis catalyst. The present invention relates to a method for conveniently preparing a supported cobalt-containing Fischer-Tropsch synthesis catalyst having improved activity and selectivity for C5 + hydrocarbons. In one aspect, the present invention provides a process for preparing a supported cobalt-containing Fischer-Tropsch synthesis catalyst, the process comprising the steps of: (a) impregnating a support material with i) a cobalt-containing compound and ii) acetic acid or a manganese salt of acetic acid in a single impregnation step to form an impregnated support material; and (b) drying and calcining the impregnated support material; wherein the support material impregnated in step (a) is not previously modified with a metal source other than cobalt; and wherein when the cobalt-containing compound is cobalt hydroxide, a manganese salt of acetic acid is not used in step (a) of the process.

Description

[0001] This application is a divisional application of parent application number 201880011231.9. The parent application was filed on February 9, 2018; the invention is entitled "Method for producing Fischer-Tropsch synthesis catalyst". Technical Field

[0002] This invention relates to a method for producing a Fischer-Tropsch synthesis catalyst. Specifically, this invention relates to a method for preparing a supported cobalt-containing Fischer-Tropsch catalyst, the method comprising simultaneously modifying a support material with a cobalt-containing compound and acetic acid or its manganese salt to provide C 5+ Hydrocarbons exhibit improved activity and selectivity as catalysts. This invention also relates to the use of acetic acid or a metal salt thereof, preferably a manganese salt thereof, in the preparation of supported cobalt-containing Fischer-Tropsch synthesis catalysts for controlling the crystallite size of cobalt oxide. Background Technology

[0003] The conversion of syngas into hydrocarbons via the Fischer-Tropsch process has been known for many years. The growing importance of alternative energy sources has witnessed a renewed interest in the Fischer-Tropsch process as one of the more attractive, direct, and environmentally acceptable pathways for producing high-quality transportation fuels.

[0004] Many metals, such as cobalt, nickel, iron, molybdenum, tungsten, thorium, ruthenium, rhenium, and platinum, are known, alone or in combination, to be catalytically active in the conversion of syngas into hydrocarbons and their oxygen-containing derivatives. Of these metals, cobalt, nickel, and iron have been the most extensively studied. Typically, metals are used in combination with support materials, the most common of which are alumina, silicon dioxide, and carbon.

[0005] In the preparation of supported cobalt Fischer-Tropsch synthesis catalysts, a solid support material is typically impregnated with a solution of a cobalt-containing compound, which may be, for example, an organometallic or inorganic compound (e.g., Co(NO3)2·6H2O). The specific form of the cobalt-containing compound is usually selected based on its ability to form cobalt oxide (e.g., CoO, Co2O3, or Co3O4) after a subsequent calcination / oxidation step. After the formation of supported cobalt oxide, a reduction step is required to form pure cobalt metal as the active catalytic species. Therefore, the reduction step is often also referred to as the activation step.

[0006] During calcination, cobalt oxide forms microcrystals on the support material, and the properties of these microcrystals, such as dispersion, particle size, and degree of reduction, are known to affect the activity and selectivity of the catalyst in the Fischer-Tropsch process. For example, de Jong et al. (J. Am. Chem. Soc., 128, 2006, 3956) pointed out that for optimal activity and selectivity, cobalt metal particles in the active catalyst with a size of approximately 6 to 8 nm are particularly advantageous.

[0007] The effects of modification of the support material or impregnation of the support material with cobalt oxide on the activity and selectivity of the active catalyst in the Fischer-Tropsch process have been investigated.

[0008] In the past, the pretreatment of support materials has been used to influence the selectivity and / or activity of cobalt-supported Fischer-Tropsch synthesis catalysts. For example, Zhang et al. (Catalysis Today, 142, 2009, 85-89) described a two-step impregnation method involving pretreatment of a silica support with acetic acid, followed by air drying at 100 °C, and then impregnation with cobalt nitrate. The authors pointed out that, with simultaneously high cobalt particle reduction, the improved dispersion of supported cobalt due to the pretreatment resulted in high catalytic activity. A reduction in cobalt oxide particle size was also observed as a result of the pretreatment; although the smallest cobalt particle size observed by X-ray diffraction (XRD) was 16 nm, significantly higher than the optimal range reported by de Jong et al.

[0009] US 7,163,963 describes the pretreatment of an alumina support with a rare earth metal compound to provide a surface layer between the support and cobalt added in a second impregnation step. This is said to promote the formation of larger and more uniform microcrystals due to the lower acidity of the surface layer, and is also said to aid in the subsequent reduction of cobalt oxide and the dispersion of the catalytically active metal.

[0010] Liu et al. (Catalysis Communications, 8, 2007, 773-776) also described the post-treatment of cobalt catalysts impregnated on silica, a two-step impregnation method involving impregnation of the silica support with cobalt nitrate, drying at 120 °C, and then treating the pre-impregnated support with acetic acid. The authors noted an improvement in catalyst activity, particularly for liquid-phase Fischer-Tropsch synthesis, for catalysts including the secondary treatment with acetic acid, which is attributed to the simultaneous maintenance of high reducibility and high dispersion of supported cobalt.

[0011] There is still a need for a convenient method for producing Fischer-Tropsch synthesis catalysts that exhibit activity towards C 5+ Improved selectivity of hydrocarbons (which are most valuable for the preparation of fuel compositions) and / or improved catalytic activity in subsequent Fischer-Tropsch reactions. Summary of the Invention

[0012] It has been unexpectedly discovered that by impregnating the support material with a combination of cobalt-containing compounds and acetic acid or a metal salt of acetic acid, such as a manganese salt of acetic acid, the size of cobalt oxide microcrystals formed on the support can be advantageously controlled to produce Fischer-Tropsch catalysts with enhanced activity and selectivity.

[0013] Therefore, the present invention provides a method for preparing a supported cobalt-containing Fischer-Tropsch synthesis catalyst, the method comprising the following steps: (a) In a single impregnation step, the carrier material is impregnated with i) a cobalt-containing compound and ii) acetic acid or a manganese salt of acetic acid to form the impregnated carrier material; and (b) Drying and calcining the impregnated carrier material; The carrier material impregnated in step (a) was not previously modified with a metal source other than cobalt; and When the cobalt-containing compound is cobalt hydroxide, manganese salt of acetic acid is not used in step (a) of the method.

[0014] The timing of the addition of acetic acid or manganese salt of acetic acid has been found to be critical in the method of the present invention. Specifically, the benefits of the invention can be achieved by impregnating the support material with a cobalt-containing compound and acetic acid or manganese salt of acetic acid in a single impregnation step, followed by drying and calcination. By modifying the support in this way, the size of the supported cobalt oxide microcrystals formed on the support material during the calcination step can be advantageously controlled compared to situations where acetic acid or manganese salt of acetic acid is not used, or where they are used in pretreatment or posttreatment (i.e., before or after drying / calcination in the impregnation with the cobalt-containing compound and in separate impregnation).

[0015] Following drying and calcination, the cobalt metal precursor, typically a cobalt nitrate salt, is decomposed, leaving cobalt oxide on the surface of the support material. During this process, the organic molecules and byproducts of the decomposition of the metal precursor are typically vaporized due to the applied high temperatures. Therefore, unexpectedly, the addition of organic compounds such as acetic acid has this positive effect on catalyst performance when acetic acid itself or the acetate of manganese acetic acid is expected to be vaporized and distilled off or thermally decomposed to the extent that undesirable carbon deposition on the support may occur. Even with a drying step performed at high temperatures, removal of small organic molecules such as acetic acid from the support material is expected, particularly when drying is carried out at 100°C or higher.

[0016] Without being constrained by any specific theory, it is considered that acetic acid or its manganese salt may undergo dissociative adsorption onto the support surface, thereby forming acetate species that influence the concurrent development of cobalt oxide microcrystals. Furthermore, it is believed that the mobility of the cobalt-containing compound and acetic acid or its manganese salt on the support surface, for example, when suspended or dissolved in an impregnation solution, allows for the full benefits of the presence of acetic acid or its manganese salt. This contrasts with the case where cobalt-containing compounds and acetic acid or its manganese salt are impregnated in separate impregnation steps, with at least one drying step between impregnations (i.e., application of acetic acid or its manganese salt in pretreatment or posttreatment).

[0017] Therefore, according to the present invention, impregnation of the support material with a cobalt-containing compound and an acetate or a manganese salt of acetic acid occurs in a single step, without any intermediate drying or calcination steps to separate the loading of different components. Therefore, according to the present invention, Fischer-Tropsch catalysts with improved activity and selectivity can be produced in a single impregnation step without the need for pretreatment or post-treatment of the support material / impregnated support material. Thus, the present invention allows for the convenient formation of catalysts with improved activity and selectivity without multiple processing steps, thereby improving efficiency.

[0018] In step (a) of the method of the present invention, the carrier material is impregnated in a single impregnation step with i) a cobalt-containing compound and ii) acetic acid or a manganese salt of acetic acid to form an impregnated carrier material.

[0019] It will be understood that the support material can be in any form, provided that it is suitable for use as a support for a Fischer-Tropsch synthesis catalyst, and that the support material has not been previously impregnated with a metal source other than cobalt, which could have a detrimental effect on the performance of the active catalyst and may hinder the benefits of the invention. Therefore, when a support material previously loaded with cobalt metal or its precursors can be used according to the invention, additional pretreatment with other metal sources should be avoided according to the invention.

[0020] A specific advantage of this invention is the convenience of modifying and converting the support material into a Fischer-Tropsch synthesis catalyst using only a single impregnation step followed by drying and calcination. Therefore, in a preferred embodiment, prior to impregnation in step (a) of the method, the support material used in this invention has not been pre-modified, for example by the addition of accelerators, dispersants, strength enhancers, and / or binders or precursors thereof. In a particularly preferred embodiment, prior to impregnation in step (a) of the method, the support material used in this invention has not been pretreated with acetic acid or a manganese salt of acetic acid.

[0021] The carrier material may be in the form of an extrusion, and the impregnation step (a) forms the impregnated extrusion prior to step (b). As used herein, "extrusion" means carrier material that has undergone an extrusion step and is thus formable. Alternatively, the carrier material may preferably be in the form of a powder or granulate. As used herein, "powder" or "granulate" of carrier material should be understood to mean free-flowing particles of carrier material or particles of carrier material that have been granulated and / or sieved into a specific shape (e.g., spherical) and size range. In the case of this invention, the powder or granules are in a form suitable for impregnation with a solution containing a cobalt compound and acetic acid or its manganese salt, and subsequent extrusion.

[0022] In a preferred embodiment, the carrier material is in the form of powder or granules, and the impregnation step (a) forms impregnated carrier powder or granules, the method further comprising extruding the impregnated carrier powder or granules prior to step (b) to form an extrudate.

[0023] In some embodiments, the carrier material is in the form of powder or granules, and the impregnation step (a) forms impregnated carrier powder or granules, and the calcination in step (b) forms calcined powder or granules, the method further comprising extruding the calcined powder or granules to form an extrudate.

[0024] Therefore, it will be understood that the carrier material impregnated with a cobalt-containing compound and acetic acid or its manganese salt can be extruded at any suitable stage before or after drying and calcination. Impregnation of the carrier material with both the cobalt-containing compound and acetic acid or manganese acetate by a single impregnation step prior to the drying and calcination steps is only necessary. It will also be understood that the cobalt-containing compound and acetic acid or its manganese salt can be impregnated onto the carrier material using a single solution / suspension of the components or by means of separate solutions / suspensions of the components sequentially mixed with the carrier material, provided that no intermediate drying or calcination steps are performed.

[0025] The carrier material used in this invention is not particularly limited and can be selected from any suitable refractory metal oxide or silicate known in the art, or a combination thereof. Preferably, the carrier material is selected from the group consisting of silica, alumina, silica / alumina, cerium dioxide, gallium oxide, zirconium oxide, titanium dioxide, magnesium oxide, zinc oxide, and mixtures thereof. More preferably, the carrier material is selected from titanium dioxide and zinc oxide. Most preferably, the carrier material is selected from titanium dioxide or mixtures containing titanium dioxide. A preferred example of titanium dioxide carrier material particles is, for example, titanium dioxide powder of P25 Degussa.

[0026] The preferred support material is substantially free of any added components that could adversely affect the catalytic activity of the system. Therefore, the support material is preferably at least 95% by weight pure, more preferably at least 98% by weight pure, and most preferably at least 99% by weight pure. Impurities are preferably less than 1% by weight, more preferably less than 0.50% by weight, and most preferably less than 0.25% by weight. The pore volume of the support is preferably greater than 0.50 ml / g and more preferably greater than 0.8 ml / g. The average pore radius of the support material (before impregnation) is 10 to 500 Å, preferably 15 to 100 Å, more preferably 20 to 80 Å, and most preferably 25 to 40 Å. The BET surface area is suitably 2 to 1000 m². 2 / g, preferably 10 to 600 m 2 / g, more preferably 15 to 100 m 2 / g, and the optimal value is 30 to 60 m 2 / g.

[0027] BET surface area, pore volume, pore size distribution, and average pore radius can be determined by nitrogen adsorption isotherms measured at 77 K using a Micromeritics TRISTAR 3000 static volumetric adsorption analyzer. The applicable procedures are British Standard Methods BS4359: Part 1: 1984 'Recommendations for gas adsorption (BET) methods' and BS7591: Part 2: 1992, 'Porosity and pore size distribution of materials' – Application of methods for evaluating gas adsorption. The obtained data can be converted using the BET method (in the pressure range of 0.05–0.20 P / Po) and the Barrett, Joyner, and Halenda (BJH) method (for pore diameters of 20–1000 Å) to produce surface area and pore size distribution, respectively.

[0028] Appropriate references for the above data conversion methods are Brunauer, S, Emmett, PH and Teller, E, J. Amer. Chem. Soc. 60, 309, (1938) and Barrett, EP, Joyner, LG and Halenda PP, J. AmChem. Soc., 1951 73 373-380.

[0029] When in powder form, the median particle size diameter (d50) is preferably less than 50 μm, more preferably less than 25 μm. When the carrier material is in granular form, the median particle size diameter (d50) is preferably 300 to 600 μm. The particle size diameter (d50) can be suitably determined using a particle size analyzer (e.g., a Microtrac S3500 particle size analyzer).

[0030] The term "impregnation" or "impregnating" as used herein is intended to refer to contacting a carrier material with a solution of a cobalt-containing compound and acetic acid or its manganese salt prior to drying, in order to precipitate the cobalt-containing compound and, where applicable, its manganese acetate salt. Impregnation with a fully dissolved solution of the cobalt-containing compound ensures good dispersion of the cobalt-containing compound on the carrier material and is therefore preferred. This contrasts with the use of a partially dissolved 'solid solution' or suspension of the cobalt-containing compound, in which case the level of dispersion of the cobalt-containing compound across the surface and pores of the carrier material can fluctuate depending on the nature of the precipitation on the carrier material. Furthermore, the use of a fully dissolved solution of the cobalt-containing compound has less impact on the resulting morphology and bulk crush strength of the extrudate formed subsequently compared to a solid solution. Nevertheless, the benefits of the invention can also be achieved when using a partially undissolved solid solution of the cobalt-containing compound.

[0031] When the powder or granules of the carrier material are contacted with a solution containing a cobalt compound and acetic acid or its manganese salt, the amount of solution used preferably corresponds to the amount of liquid suitable for achieving a mixture with a suitable consistency for further processing, such as extrusion molding. In this case, complete removal of the solvent from the impregnation solution can be achieved after the extrudate is formed.

[0032] Suitable cobalt-containing compounds are those that can thermally decompose into cobalt oxides upon calcination and are completely soluble in the impregnation solution. Preferred cobalt-containing compounds are cobalt nitrates, acetates, hydroxides, or acetylacetonates, with cobalt nitrates, such as cobalt nitrate hexahydrate, being most preferred. Halides are preferably avoided, as these substances have been found to be harmful. In some embodiments, the cobalt-containing compound is not cobalt hydroxide.

[0033] Preferably, the impregnation step (a) provides a synthetic catalyst containing 5% to 20% by weight of cobalt, preferably 7.5% to 12.5% ​​by weight, based on the total weight of the supported synthetic catalyst.

[0034] Preferably, in step (a), the carrier material is impregnated with acetic acid in an amount of 0.1 to 5% by weight, preferably 0.25 to 3.5% by weight, based on the dry weight of the impregnated carrier material; or in step (a), the carrier material is impregnated with a manganese salt of acetic acid in an amount of 0.1 to 5% by weight, preferably 0.25 to 3.5% by weight, more preferably 0.5 to 2.5% by weight, and most preferably 0.8 to 1.2% by weight.

[0035] It has been found that impregnating the support material with acetic acid in step (a) is particularly advantageous. The addition of acetic acid at this stage conveniently controls the size of the cobalt oxide crystallites formed on the support material, and this effect has also been found to be largely independent of the amount of acetic acid added to the support. Specifically, it has been unexpectedly found that further increases in the acetic acid loading onto the support material beyond a point do not result in a further decrease in the cobalt oxide crystallite size. Instead, the cobalt oxide crystallite size conveniently stabilizes to a size range that has been found particularly desirable for Fischer-Tropsch selectivity and activity after reduction to provide active cobalt metal. Specifically, the addition of acetic acid advantageously results in the formation of cobalt oxide crystallites with a size close to an optimal value of approximately 8 nm. Furthermore, those skilled in the art can readily ensure that the conditions selected for the reduction of cobalt oxide crystallites to cobalt metal during activation to reduction of the catalyst result in a cobalt metal particle size that is the same as or similar to the size of the cobalt oxide crystallites before reduction.

[0036] Similarly, the addition of manganese salts to acetic acid was found to reduce the size of cobalt oxide crystallites to a level more favorable to increasing activity and C. 5+ The optimal range for enhanced selectivity. Therefore, the use of manganese salts of acetic acid allows the size range of cobalt oxide crystallites to be optimized for the advantageous performance of the active catalyst in the Fischer-Tropsch process.

[0037] It has also been discovered that, according to another aspect of the invention, certain additional metal salts of acetic acid may be used to control the size of cobalt oxide crystallites. Therefore, the invention can be used to reduce cobalt crystallites to below a desired upper limit of particle size (e.g., below 12 nm, preferably below 10 nm), or to ensure that the size of cobalt oxide crystallites impregnated on a carrier material is generally within a desired particle size range (e.g., between 6 and 10 nm, preferably 7 to 9 nm, for example 8 nm).

[0038] The impregnation of the carrier material with a cobalt-containing compound and acetic acid or its manganese salt according to the method of the invention can be carried out by any suitable method known to those skilled in the art, such as by vacuum impregnation, incipient wetness, or immersion in an excess liquid. The solvent of the impregnation solution can be an aqueous solvent or a non-aqueous organic solvent. Suitable non-aqueous organic solvents include, for example, alcohols (e.g., methanol, ethanol, and / or propanol), ketones (e.g., acetone), liquid paraffinic hydrocarbons, and ethers. Alternatively, aqueous organic solvents, such as aqueous alcohol solvents, can be used. Preferably, the solvent of the impregnation solution is an aqueous solvent.

[0039] In a preferred embodiment, in step (a), the carrier material is impregnated with a single solution or suspension containing both a cobalt-containing compound and acetic acid or its manganese salt. Preferably, the solution or suspension is an aqueous solution or suspension.

[0040] The concentrations of the cobalt compound and acetic acid or its manganese salt in the impregnation solution are not particularly limited, but it is preferable that the cobalt compound is completely dissolved. When the powder or granules of the support material are impregnated and immediately followed by an extrusion step, the amount of impregnation solution is preferably suitable for forming an extrudable paste. Preferably, the concentration of the impregnation solution is sufficient to provide 5% to 20% by weight, preferably 7.5% to 12.5% ​​by weight, of cobalt based on the total weight of the supported synthetic catalyst after drying and calcination. A suitable concentration of the cobalt compound is, for example, 0.1 to 15 mol / L.

[0041] According to the invention, the impregnation of the carrier material is followed by drying of the impregnation solution to allow the cobalt-containing compound to precipitate onto the carrier material, and preferably also to remove the binding solvent (e.g., water) of the impregnation solution. Therefore, drying does not lead to the decomposition of the cobalt-containing compound or otherwise cause a change in the oxidation state of the cobalt-containing compound. As will be understood, in embodiments where extrusion is performed, complete drying and removal of the solvent (e.g., binding solvent) of the impregnation solution can occur after extrusion. According to the invention, drying is suitably carried out at a temperature of 50°C to 150°C, preferably 75°C to 125°C. Suitable drying times are from 5 minutes to 72 hours. Drying can suitably be carried out, for example, at high temperatures in an inert gas flow in a drying oven or box furnace.

[0042] In the case of impregnated extrudates according to the present invention, it will be understood that the carrier may be contacted with the impregnation solution by any suitable method, including, for example, vacuum impregnation, initial wet impregnation or immersion in an excess liquid.

[0043] In the case of impregnating a powder or granules of carrier material, the powder or granules may be mixed with the impregnation solution by any suitable method known to a person skilled in the art, such as by adding the powder or granules to a container of the impregnation solution and stirring. In the case where the extrusion step immediately follows the impregnation of the powder or granules, the mixture of powder or granules and impregnation solution may be further processed if it is not yet in a form suitable for extrusion. For example, the mixture may be ground to reduce the presence of larger particles that may be difficult to extrude or that would otherwise impair the physical properties of the resulting extrudate. Grinding typically involves forming a paste suitable for extrusion. In the case of this invention, any suitable grinding or kneading equipment known to a person skilled in the art may be used for grinding. For example, pestles and mortars may be suitably used in some applications, or a Simpson mill may be suitably employed. Grinding is typically carried out over a period of 3 to 90 minutes, preferably 5 to 30 minutes. Grinding may suitably be carried out within a temperature range including ambient temperature. A preferred temperature range for grinding is 15°C to 50°C. Grinding may suitably be carried out under ambient pressure. As described above, it will be understood that complete removal of the combined solvent from the impregnation solution can be performed to achieve complete precipitation after extrusion.

[0044] In embodiments where the impregnated powder or granules are calcined to completely remove the solvent from the impregnation solution, the calcined powder or granules may be further processed to form a mixture suitable for extrusion. For example, an extrudable paste may be formed by combining the calcined powder or granules with a suitable solvent, such as an impregnation solvent, preferably an aqueous solvent, and grinding as described above.

[0045] According to the method of the present invention, the preparation of the supported Fischer-Tropsch synthesis catalyst involves a calcination step in step (b). As will be understood, calcination is necessary to convert the cobalt-containing compound impregnated on the support material into cobalt oxide. Therefore, calcination results in the thermal decomposition of the cobalt-containing compound, rather than merely removing the binding solvent of the impregnation solution as in the drying case according to the present invention.

[0046] Calcination can be carried out by any method known to those skilled in the art, for example, at a temperature of at least 250°C, preferably 275°C to 500°C, in a fluidized bed or rotary kiln. In some embodiments, calcination can be carried out as part of an integrated method, wherein calcination and reductive activation of the synthesis catalyst to produce a reduced synthesis catalyst are carried out in the same reactor.

[0047] The supported Fischer-Tropsch synthesis catalyst prepared according to the method of the present invention may additionally contain one or more promoters, dispersants, or binders. Promoters are typically added to preferably promote the reduction of cobalt oxide to cobalt metal at a lower temperature. Preferably, one or more promoters are selected from a list consisting of ruthenium, palladium, platinum, rhodium, rhenium, manganese, chromium, nickel, iron, molybdenum, tungsten, zirconium, gallium, thorium, lanthanum, cerium, and mixtures thereof. Promoters are typically used in an atomic ratio of cobalt to promoter of at most 250:1, more preferably at most 125:1, still more preferably at most 25:1, and most preferably 10:1. In a preferred embodiment, one or more promoters are present in the obtained cobalt-containing Fischer-Tropsch synthesis catalyst in an amount of 0.1 wt% to 3 wt% on an elemental basis, based on the total weight of the supported synthesis catalyst.

[0048] The addition of accelerators, dispersants, strength enhancers, or binders can be integrated at several stages of the method according to the invention, provided that the carrier material impregnated in step a) does not contain a metal source other than cobalt. Preferably, the accelerator, dispersant, or binder, or precursors thereof, is introduced during impregnation step (a). As will be understood by those skilled in the art, the use of a manganese salt of acetic acid in embodiments according to the invention also represents a method of introducing a manganese accelerator metal into the carrier material. Similarly, in the case of the use of certain additional metal salts of acetic acid according to other aspects of the invention, this can also represent a method of introducing an accelerator metal into the carrier material.

[0049] The Fischer-Tropsch synthesis catalyst prepared according to the present invention can be conveniently converted into a reduced Fischer-Tropsch synthesis catalyst by reducing activation through any known method known to those skilled in the art capable of converting cobalt oxide into active cobalt metal. Therefore, in one embodiment, the method of the present invention further comprises reducing the obtained cobalt-containing Fischer-Tropsch synthesis catalyst to form a reduced Fischer-Tropsch synthesis catalyst.

[0050] In yet another aspect, the present invention also provides a supported cobalt-containing Fischer-Tropsch synthesis catalyst that is obtained or available by the methods described herein.

[0051] The steps for forming the reducing synthesis catalyst can be carried out batch or continuously in a fixed-bed, fluidized-bed, or slurry-bed reactor. The reducing synthesis catalyst formed after the reductive activation process can be used in the heterogeneous catalytic production of hydrocarbons from syngas via Fischer-Tropsch synthesis, for example, for the production of diesel or aviation fuels or their precursors. The Fischer-Tropsch synthesis of hydrocarbons from syngas can be represented by reaction formula 1: m CO + (2m+l) H2→ m H2O + C m H 2m+2 Reaction 1 As discussed above, it has been unexpectedly discovered that the method of the present invention provides a way to exhibit high C 5+ Hydrocarbon-selective Fischer-Tropsch catalysts. Furthermore, superior catalytic activity has been found in at least some embodiments. Therefore, the cobalt-containing Fischer-Tropsch catalyst produced according to the method of the invention provides gasoline-range hydrocarbons when used in Fischer-Tropsch reactions.

[0052] Therefore, in another aspect, the present invention also provides a method for converting a feed comprising a mixture of hydrogen and carbon monoxide gases, preferably in the form of a syngas mixture, into hydrocarbons, the method comprising contacting the mixture of hydrogen and carbon monoxide with a supported cobalt-containing Fischer-Tropsch synthesis catalyst as defined above.

[0053] In the Fischer-Tropsch reaction described above, the volume ratio of hydrogen to carbon monoxide (H2:CO) in the gaseous reaction mixture is preferably in the range of 0.5:1 to 5:1, more preferably 1:1 to 3:1, and most preferably 1.6:1 to 2.2:1. The gaseous reaction stream may also contain other gaseous components, such as nitrogen, carbon dioxide, water, methane, and other saturated and / or unsaturated light hydrocarbons, each preferably present at a concentration of less than 30% by volume. The temperature of the Fischer-Tropsch reaction is preferably in the range of 100 to 400°C, more preferably 150 to 350°C, and most preferably 150 to 250°C. The pressure is preferably in the range of 1 to 100 bar (0.1 to 10 MPa), more preferably 5 to 75 bar (0.5 to 7.5 MPa), and most preferably 10 to 50 bar (1.0 to 5.0 MPa).

[0054] In another aspect of the invention, a supported cobalt-containing Fischer-Tropsch synthesis catalyst as defined herein is provided for improving the Fischer-Tropsch process for the production of C. 5+ Applications of hydrocarbon selectivity and / or improving conversion rates in the Fischer-Tropsch process.

[0055] In another aspect of the invention, the use of acetic acid or a metal salt of acetic acid in the preparation of supported cobalt-containing Fischer-Tropsch synthesis catalysts for controlling the size of cobalt oxide crystallites is provided, wherein the metal is selected from the group consisting of ruthenium, palladium, platinum, rhodium, rhenium, manganese, chromium, nickel, iron, molybdenum, tungsten, zirconium, gallium, thorium, lanthanum, cerium and mixtures thereof; preferably wherein the metal is selected from manganese, ruthenium, rhenium and platinum, and more preferably manganese.

[0056] It will be understood that, in the context of the use of metal salts of acetic acid other than manganese salts of acetic acid in this invention, the preparation method and the general properties of the supported cobalt-containing Fischer-Tropsch synthesis catalyst will be generally as described above with respect to manganese salts of acetic acid.

[0057] In another aspect of the invention, there is a method to improve the efficiency of the Fischer-Tropsch process in producing C 5+ Methods for selecting hydrocarbons and / or increasing conversion in the Fischer-Tropsch process, the methods comprising the step of supplying a cobalt-containing Fischer-Tropsch synthesis catalyst as defined above to the Fischer-Tropsch process.

[0058] In another aspect of the invention, a method for controlling the size of cobalt oxide crystallites in the preparation of a supported cobalt-containing Fischer-Tropsch synthesis catalyst is provided, the method comprising the step of supplying acetic acid or a metal salt of acetic acid during impregnation of a support material with a cobalt-containing compound, wherein the metal is selected from the group consisting of ruthenium, palladium, platinum, rhodium, rhenium, manganese, chromium, nickel, iron, molybdenum, tungsten, zirconium, gallium, thorium, lanthanum, cerium and mixtures thereof; preferably wherein the metal is selected from manganese, ruthenium, rhenium and platinum, and more preferably manganese.

[0059] The invention will now be further described with reference to the following illustrative examples only. In the examples, CO conversion is defined as the number of moles of CO used / the number of moles of CO in the feed × 100, and carbon selectivity is defined as the number of moles of CO attributable to a particular product / the number of moles of CO converted × 100. Unless otherwise specified, the temperature mentioned in the examples is the applied temperature and not the catalyst / bed temperature. Unless otherwise specified, the pressure mentioned in the examples is the absolute pressure. Detailed Implementation

[0060] Example 1 Catalyst preparation - using manganese salts of acetic acid 55.6 g of Co(NO3)2·6H2O and varying amounts of Mn(OAc)2 (see Table 1) were mixed with a small amount of water in a solution. This mixture was then slowly added to 100 g of P25 TiO2 powder and mixed to obtain a homogeneous mixture. Co(NO3)2·6H2O was used in an amount that yielded 10 wt% elemental Co on TiO2. The resulting paste / particle was extruded to form extruded pellets, which were subsequently dried and calcined at 300 °C.

[0061] Table 1 Mn loading capacity 1% by weight 1.5% by weight 2% by weight 3% by weight 5% by weight 10% by weight <![CDATA[Mass of Mn(OAc)2]]> 5.4 g 8.1 g 10.8 g 16.2 g 27.0 g 54.0 g Example 2 Catalyst preparation - using acetic acid 14.82 g of Co(NO3)2·6H2O and varying amounts of acetic acid (see Table 2) were mixed with a small amount of water in a solution. This mixture was then slowly added to 27 g of P25 TiO2 powder and mixed to obtain a homogeneous mixture. Co(NO3)2·6H2O was used in an amount that yielded 10 wt% elemental Co on the TiO2. The resulting paste / particle was extruded to form extruded pellets, which were subsequently dried and calcined at 300 °C.

[0062] Table 2 AcOH loading 0.5% by weight 1% by weight 2% by weight 3% by weight AcOH quality 0.656 g 1.310 g 2.620 g 3.930 g Comparative Example 1 Catalyst preparation - without using acetic acid or manganese acetate 14.8 g of Co(NO3)2·6H2O was mixed with a small amount of water in a solution. This mixture was then slowly added to 27 g of P25 TiO2 powder and mixed to obtain a homogeneous mixture. Co(NO3)2·6H2O was used in an amount that yielded 10 wt% elemental Co on the TiO2. The resulting paste / particle was extruded to form extruded pellets, which were subsequently dried and calcined at 300 °C.

[0063] Comparative Example 2 Catalyst preparation - without using acetic acid or manganese acetate 14.82 g of Co(NO3)2·6H2O and 0.98 g of Mn(NO3)2 were mixed with a small amount of water in a solution. This mixture was then slowly added to 27 g of P25 TiO2 powder and mixed to obtain a homogeneous mixture. Co(NO3)2·6H2O was used in an amount that yielded 10 wt% elemental Co on the TiO2. The resulting paste / particle was extruded to form extruded pellets, which were subsequently dried and calcined at 300 °C.

[0064] Example 3 Catalyst preparation - manganese nitrate and acetic acid The procedure of Comparative Example 2 was followed, except that 0.656 g of acetic acid was added together with Co(NO3)2·6H2O and Mn(NO3)2.

[0065] Comparative Example 3 Catalyst preparation - using manganese acetate (sequential impregnation) 5.93 g of Co(NO3)2·6H2O was mixed with a small amount of water in a solution. This mixture was then slowly added to 10.7 g of P25 TiO2 powder and mixed to obtain a homogeneous mixture. Co(NO3)2·6H2O was used in an amount that imparted 10 wt% elemental Co to TiO2. The resulting paste / particle was extruded to form extruded pellets, which were then dried and calcined at 300 °C. The resulting Co / TiO2 catalyst was impregnated with 0.54 g of Mn(OAc)2 to impart 1 wt% Mn to TiO2, then dried and calcined to produce a sequentially impregnated CoMn / TiO2 catalyst.

[0066] Example 4 Effects of Mn(OAc)2 and Acetic Acid on Co3O4 Particle Size The average size of Co3O4 microcrystals on the TiO2 support was measured by X-ray diffraction analysis of the catalyst prepared by the above procedure.

[0067] Table 3 shows the crystallite sizes of the catalysts prepared by the methods of Examples 1 to 3 and Comparative Examples 1 to 3.

[0068] Table 3 Example <![CDATA[Catalyst of 10 wt% Co on TiO2 prepared as follows:]]> <![CDATA[Average size of Co3O4 (nm)]]> Example 1 <![CDATA[1 wt% Mn (Mn(OAc)2)]]> 8.1 <![CDATA[1.5 wt% Mn (Mn(OAc)2)]]> 5.7 <![CDATA[2 wt% Mn (Mn(OAc)2)]]> 4.9 <![CDATA[3 wt% Mn (Mn(OAc)2)]]> 3.4 <![CDATA[5 wt% Mn (Mn(OAc)2)]]> 2.3 <![CDATA[10 wt% Mn (Mn(OAc)2)]]> 2.8 Example 2 0.5% by weight acetic acid 8.9 1% acetic acid 7.3 2% acetic acid 8.3 3% acetic acid 8.4 Comparative Example 1 not applicable 10.7 Comparative Example 2 <![CDATA[1 wt% Mn (Mn(NO3)2)]]> 12.1 Example 3 <![CDATA[1 wt% Mn (Mn(NO3)2) + AcOH]]> 7.8 Comparative Example 3 <![CDATA[1 wt% Mn (Mn(OAc)2) (Sequential impregnation)]]> 20.9 The results in Table 3 show that the size of Co3O4 crystallites can be controlled during catalyst preparation by adding acetic acid or its manganese salt. The addition of manganese acetate achieved the optimal crystallite size (approximately 8 nm) at a loading of 1%, and the size decreased with increasing manganese acetate loading. However, when using any amount above 0.5% loading, the addition of acetic acid was found to give an optimal crystallite size of approximately 8 nm.

[0069] The addition of both acetic acid and manganese acetate showed improvements over Comparative Example 1, which used only cobalt nitrate without any acetic acid or manganese acetate. Comparative Example 2 showed that using manganese nitrate instead of manganese acetate did not produce the same favorable reduction in crystallite size. However, Example 3 clearly showed that by adding acetic acid to both manganese nitrate and cobalt, a crystallite size of approximately 8 nm was obtained.

[0070] Comparative Example 3 shows that the benefits of the present invention cannot be obtained by subsequently impregnating the dried and calcined Co / TiO2 catalyst with manganese acetate, followed by further drying and calcination.

[0071] Example 5 General Procedure of Fischer-Tropsch Reaction 10 ml of catalyst was loaded into a microreactor and reduced under H2 flow (15 h, 300 °C, 100% H2, 0.1 MPa). The gas supply was switched to a mixture of hydrogen and carbon monoxide containing 18% nitrogen (H2 / CO = 1.8), and the pressure was maintained at 4.3 MPa. The temperature was increased to 195 °C and maintained throughout the Fischer-Tropsch reaction.

[0072] Example 6 Effects of Mn(OAc)2 and acetic acid on the Fischer-Tropsch reaction In the Fischer-Tropsch synthesis according to Example 5, a catalyst prepared according to Example 1 was used with 9.88 g Co(NO3)2·6H2O, 21.4 g P25 TiO2 powder, and varying amounts of Mn(OAc)2 (0.09 g–0.1 wt% Mn; 0.22 g–0.25 wt% Mn; 0.45 g–0.5 wt% Mn; 0.89 g–1 wt% Mn; 1.79 g–2 wt% Mn). The results are shown in Table 4.

[0073] CO conversion, CH4 selectivity, C 5+ Selectivity and C 5+ Productivity data were compiled, and the results of the above embodiments are provided in Table 4 below. Exhaust gas samples were taken and analyzed using online mass spectrometry. C was determined by the difference between the gas phase and the C1-C4 components. 5+ Selectivity. Through interaction with C in the gas phase. 2+ The CH4 selectivity was determined by the differences in components. Catalyst productivity was defined as the weight in grams of product formed on the catalyst per liter of packed catalyst volume per hour of reaction time. CO conversion, CH4 selectivity, C 5+ The values ​​for selectivity and productivity are averages obtained under steady-state conditions.

[0074] Table 4. <![CDATA[Catalyst of 10 wt% Co on TiO2 prepared as follows:]]> <![CDATA[GHSV(h −1 )]]> CO conversion rate (%) <![CDATA[CH4 selectivity (%)]]> <![CDATA[C 5+ Selectivity (%) <![CDATA[CH4 productivity (g / h / l)]]> <![CDATA[C 5+ Productivity (g / h / l) <![CDATA[C 5+ / CH4 Productivity]]> 0.1% by weight Mn 690 34.7 16.2 75.4 9.2 42.9 4.66 0.25% by weight Mn 697 42.7 14.6 78.2 10.3 55.1 5.35 0.5% by weight Mn 725 50.8 13.6 79.9 11.6 68.3 5.89 1% by weight Mn 682 56.3 12.2 81.3 11.1 74.0 6.67 2% by weight Mn 691 54.1 12.0 78.4 10.3 68.1 6.61 The results in Table 4 show that, under isothermal and pressure conditions, the activity of the CoMn / TiO2 catalyst increases with increasing manganese acetate loading, reaching a maximum at 1 wt% manganese acetate, which corresponds to a loading that yields approximately 8 nm Co3O4 crystallites. Crucially, increasing the manganese acetate loading also results in increased C3... 5+The ratio of / CH4 productivity again reaches its maximum at a loading of 1% manganese acetate.

[0075] Additionally, Table 5 below shows the effect of the rate on CO conversion per gram of catalyst for simultaneous impregnation with manganese acetate (as in Example 1), sequential impregnation with manganese acetate (as in Comparative Example 3), and non-utilization of manganese acetate (as in Comparative Example 1). The rate is defined as the number of mmol of CO converted per gram of catalyst per hour.

[0076] The results in Table 5 further demonstrate that the benefits of the present invention cannot be obtained through sequential impregnation.

[0077] Table 5. Loading volume (weight %) Immersion <![CDATA[GHSV (h -1 )]]> Rate (mmol / h / g) 0% not applicable 1550 3.2 1% by weight Mn At the same time (along with cobalt) 1500 5.0 1% by weight Mn Order (after cobalt) 710 3.8

Claims

1. A method for preparing a supported cobalt-containing Fischer-Tropsch synthesis catalyst, the method comprising the following steps: (a) In a single impregnation step, the carrier material is impregnated with i) a cobalt-containing compound and ii) acetic acid or a manganese salt of acetic acid to form the impregnated carrier material; and (b) Drying and calcining the impregnated carrier material; The carrier material impregnated in step (a) was not previously modified with a metal source other than cobalt; and When the cobalt-containing compound is cobalt hydroxide, manganese salt of acetic acid is not used in step (a) of the method.

2. The method of claim 1, wherein the carrier material is in the form of powder or granules, and the impregnation step (a) forms impregnated carrier powder or granules, the method further comprising extruding the impregnated carrier powder or granules prior to step (b) to form an extrudate.

3. The method of claim 1, wherein the carrier material is in the form of powder or granules, and the impregnation step (a) forms impregnated carrier powder or granules, and the calcination in step (b) forms calcined powder or granules, the method further comprising extruding the calcined powder or granules to form an extrudate.

4. The method according to claim 2 or 3, wherein the carrier material is in the form of a powder having a median particle size diameter (d50) of less than 50 μm, preferably less than 25 μm; or wherein the carrier material is in the form of granules having a median particle size diameter (d50) of 300 to 600 μm.

5. The method according to claim 1, wherein the carrier material is in the form of an extrusion, and the impregnation step (a) is performed prior to step (b) to form the impregnated extrusion.

6. The method according to any one of the preceding claims, wherein the carrier material is impregnated with a solution or suspension comprising i) the cobalt-containing compound and ii) acetic acid or a manganese salt of acetic acid.

7. The method according to claim 6, wherein the solution or suspension is an aqueous solution or suspension.

8. The method according to any one of the preceding claims, wherein the cobalt-containing compound is a cobalt nitrate, acetate, hydroxide or acetylacetonate, preferably a cobalt nitrate, such as cobalt nitrate hexahydrate.

9. The method according to any one of the preceding claims, wherein in step (a) the carrier material is impregnated with acetic acid in an amount of 0.1 to 5% by weight, preferably 0.25 to 3.5% by weight, based on the dry weight of the impregnated carrier material; or wherein in step (a) the carrier material is impregnated with a manganese salt of acetic acid in an amount of 0.1 to 5% by weight, preferably 0.25 to 3.5% by weight, more preferably 0.5 to 2.5% by weight, and most preferably 0.8 to 1.2% by weight.

10. The method according to any one of the preceding claims, wherein the impregnation step (a) provides a synthetic catalyst containing 5% to 20% by weight of cobalt, preferably 7.5% to 12.5% ​​by weight, on an elemental basis based on the total weight of the supported synthetic catalyst.