Composite catalyst carrier as well as preparation method and application thereof

Abstract

The invention provides a composite catalyst carrier as well as a preparation method and application thereof. The composite catalyst carrier comprises the following raw material components in parts by weight: 80-100 parts of silicon dioxide; 5-15 parts by weight of a pore forming agent; 2-10 parts by weight of an extrusion aid; 8-30 parts by weight of carbon fiber; and 9.5 to 140 parts by weight of a binder. The composite catalyst carrier disclosed by the invention shows surface uniformity, high mechanical strength, relatively large specific surface area, excellent heat transfer performance and rich pore structures, and a catalyst prepared by adopting the composite catalyst carrier prepared by the invention shows excellent catalytic activity and olefin selectivity in a Fischer-Tropsch synthesis reaction.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a composite catalyst carrier and a preparation method and application thereof. Background Art

[0002] Fischer-Tropsch Synthesis (FTS) is a key technology for catalytically converting synthesis gas (CO + H2) into long-chain hydrocarbons (such as diesel and aviation kerosene) and chemicals. It has important strategic significance in the utilization of carbon resources through coal-to-liquids, natural gas-to-liquids, and renewable energy coupling. However, industrial catalysts based on fixed-bed reactors still face challenges in efficiency and stability, product selectivity regulation, mass transfer limitations, and heat transfer limitations. Traditional industrial FTS catalysts (such as Co / SiO2, Fe / SiO2, and Ru / SiO2) are limited by the physicochemical properties of a single carrier and cannot meet the requirements of activity, stability, and selectivity simultaneously. In particular, for reactions of high-value-added chemicals such as olefins from synthesis gas via the Fischer-Tropsch reaction pathway, product diffusion, catalyst strength, and transition hydrogenation have restricted the development of related industrial catalysts.

[0003] As an inorganic material with stable chemical properties, excellent mechanical strength, and a porous structure, silica is widely used as a catalyst support. Its customizable pore structure and surface properties, combined with optimized molding processes, provide ideal physicochemical properties for fixed-bed catalysts. In industrial catalytic processes, silica supports play a crucial role in efficient mass transfer, high stability, and maximum utilization of active components. These functions directly determine the reactor's processing capacity, energy consumption, and economic efficiency. While current silica support extrusion technology meets the basic requirements of industrial catalysis, it still has significant deficiencies in mechanical strength, pore structure control, and heat transfer. In chemical reactions such as Fischer-Tropsch synthesis to olefins, which require high pressures (>2 MPa), silica particles are prone to breakage, leading to increased bed pressure drop and loss of active components. Furthermore, the limited porosity of silica supports hinders both syngas diffusion and desorption of long-chain unsaturated hydrocarbons in the Fischer-Tropsch synthesis reaction, resulting in a broad product distribution and excessive product hydrogenation. To overcome these limitations of single supports, it is crucial to develop enhanced composite catalyst supports through multi-material synergy and structural optimization to achieve comprehensive improvements in various performance characteristics. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a composite catalyst carrier and its preparation method and application, which are used to solve the problems of low mechanical strength, small pore size, small specific surface area and insufficient heat transfer performance of the single silica carrier in the prior art.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a composite catalyst carrier, a preparation method thereof, and an application thereof.

[0006] The first aspect of the present invention provides a composite catalyst support, which comprises the following raw material components in parts by weight:

[0007]

[0008] Preferably, the silicon dioxide is 80 to 95 parts by weight; for example, it can be 80 parts by weight, 81 parts by weight, 82 parts by weight, 83 parts by weight, 84 parts by weight, 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight, 90 parts by weight, 91 parts by weight, 92 parts by weight, 93 parts by weight, 94 parts by weight or 95 parts by weight.

[0009] Preferably, the pore-forming agent is 5 to 13 parts by weight; for example, it can be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight or 13 parts by weight.

[0010] Preferably, the extrusion aid is 2 to 8 parts by weight; for example, it can be 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight or 8 parts by weight.

[0011] Preferably, the carbon fiber is 8 to 30 parts by weight; for example, it can be 8 parts by weight, 10 parts by weight, 12 parts by weight, 15 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 25 parts by weight, 28 parts by weight or 30 parts by weight.

[0012] Preferably, the binder is 30 to 130 parts by weight; for example, it can be 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight, 100 parts by weight, 110 parts by weight, 120 parts by weight or 130 parts by weight.

[0013] The pore-forming agent of the present invention can regulate the pore structure of the carrier and increase the specific surface area and porosity.

[0014] The extrusion aid of the present invention can improve the plasticity of the carrier material and facilitate extrusion molding.

[0015] Preferably, the pore-forming agent is any one or more selected from starch, cellulose, chitosan, and lignin.

[0016] More preferably, the pore-forming agent is starch.

[0017] Preferably, the extrusion aid is sesbania powder.

[0018] Preferably, the length of the carbon fiber is 500nm to 8mm, including but not limited to 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 5μm, 10μm, 50μm, 100μm, 150μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm or 8mm.

[0019] The carbon fibers added in the present invention may be carbon fibers of any one size as described above, or may be mixed carbon fibers selected from carbon fibers of any multiple sizes as described above.

[0020] In some preferred embodiments of the present invention, the carbon fiber is composed of nano-scale carbon fiber and millimeter-scale carbon fiber.

[0021] In other preferred embodiments of the present invention, the carbon fiber is composed of micron-sized carbon fiber and millimeter-sized carbon fiber.

[0022] In other preferred embodiments of the present invention, the carbon fiber is composed of nano-scale carbon fiber and micron-scale carbon fiber.

[0023] Nano-scale and micron-scale carbon fibers can enhance interface bonding, millimeter-scale carbon fibers can form a three-dimensional skeleton structure of the carrier, and the mixed use of carbon fibers of multiple sizes can more effectively and synergistically enhance the compressive resistance of the carrier.

[0024] Preferably, the carbon fibers include at least millimeter-scale carbon fibers.

[0025] More preferably, the length of the carbon fiber is at least 1 mm or more.

[0026] More preferably, the carbon fiber further includes nano-scale carbon fiber or micron-scale carbon fiber.

[0027] More preferably, the carbon fiber is a mixed carbon fiber formed by compounding carbon fibers having a length of 500 nm to 500 μm and a length of 1 to 8 mm; in the mixed carbon fiber, the mass ratio of the carbon fibers having a length of 500 nm to 500 μm and the carbon fibers having a length of 1 to 8 mm is 1:(0.1 to 10); for example, it can be 1:0.1, 1:0.2, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10.

[0028] Preferably, the diameter of the carbon fiber is 150 nm to 10 μm; for example, it can be 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 5 μm, 7 μm or 10 μm.

[0029] Preferably, the particle size of the silicon dioxide is 10 to 100 nm; for example, it may be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0030] Preferably, the specific surface area of ​​the silicon dioxide is 50 to 380 m 2 / g; for example, it can be 50m 2 / g、100m 2 / g, 150m 2 / g, 200m 2 / g, 250m 2 / g、300m 2 / g、350m 2 / g or 380m 2 / g.

[0031] Preferably, the composite catalyst carrier further comprises a binder.

[0032] More preferably, the binder is any one or more selected from silica sol, alumina sol, polyvinyl alcohol, carboxymethyl cellulose, and polyethylene glycol.

[0033] More preferably, the degree of polymerization of the polyvinyl alcohol is 1500 to 2000; for example, it may be 1500, 1600, 1700, 1800, 1900 or 2000.

[0034] More preferably, the viscosity of the carboxymethyl cellulose is 200-2000 mPa·s; for example, it can be 200 mPa·s, 500 mPa·s, 800 mPa·s, 1000 mPa·s, 1200 mPa·s, 1500 mPa·s or 2000 mPa·s.

[0035] More preferably, the average molecular weight of the polyethylene glycol is 1500-3000 Da; for example, it can be 1500 Da, 1800 Da, 2000 Da, 2200 Da, 2500 Da, 2700 Da, 2800 Da or 3000 Da.

[0036] Preferably, the lateral compression strength of the composite catalyst carrier is 60 to 180 N / cm.

[0037] Further preferably, the lateral compression strength of the composite catalyst support is 80 to 180 N / cm; for example, it can be 80 N / cm, 85 N / cm, 90 N / cm, 95 N / cm, 100 N / cm, 110 N / cm, 120 N / cm, 130 N / cm, 140 N / cm, 150 N / cm, 160 N / cm, 170 N / cm or 180 N / cm.

[0038] Preferably, the specific surface area of ​​the composite catalyst carrier is greater than 300m 2 / g.

[0039] More preferably, the specific surface area of ​​the composite catalyst carrier is 300 to 350 m 2 / g.

[0040] More preferably, the specific surface area of ​​the composite catalyst carrier is 300 to 320 m 2 / g; for example, it can be 300m 2 / g、302m 2 / g、305m 2 / g、308m 2 / g、310m 2 / g、312m 2 / g、315m 2 / g、318m 2 / g、320m 2 / g.

[0041] The second aspect of the present invention provides a method for preparing a composite catalyst carrier, which comprises: mixing silica, a pore-forming agent, an extrusion aid and carbon fiber to form a mixture, dissolving a binder in water to form a binder solution, kneading the mixture and the binder solution to form a plastic body, processing the plastic body into a wet-molded body through an extrusion molding process, and subjecting the wet-molded body to a first drying and a first calcination to obtain a composite catalyst carrier.

[0042] The kneading described in the present invention is carried out by using a kneader.

[0043] The shape of the composite catalyst carrier of the present invention is determined by the shape of the extrusion die. The composite catalyst carrier is in the shape of an elongated strip, and the cross-section thereof can be in various shapes such as a cylinder and a clover leaf.

[0044] Preferably, the amount of the binder solution added is 100 to 300 wt % based on the total weight of the mixture.

[0045] Further preferably, the binder solution is added in an amount of 150 to 250 wt% based on the total weight of the mixture; for example, it can be 150 wt%, 160 wt%, 170 wt%, 180 wt%, 190 wt%, 200 wt%, 210 wt%, 220 wt%, 230 wt%, 240 wt% or 250 wt%.

[0046] Preferably, the concentration of the binder in the binder solution is 10 to 30 wt%.

[0047] Further preferably, the concentration of the binder in the binder solution is 20 to 30 wt%; for example, it can be 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt% or 30 wt%.

[0048] Preferably, the first drying is performed at a temperature of 20 to 180 °C.

[0049] Further preferably, the first drying is performed at a temperature of 20 to 150 °C; for example, it can be 20 °C, 25 °C, 30 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C.

[0050] Preferably, the first drying is performed for a time period of 10 to 33 h.

[0051] Further preferably, the first drying is performed for a time period of 20 to 30 h; for example, it can be 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h, 28 h, 29 h or 30 h.

[0052] Further preferably, the first drying is performed using temperature-programmed drying, specifically comprising:

[0053] 1) drying at 20 to 30 °C for 8 to 15 h;

[0054] 2) drying at 35 to 50 °C for 4 to 6 h;

[0055] 3) drying at 70 to 90 °C for 4 to 6 h;

[0056] 4) drying at 100 to 120 °C for 4 to 6 h.

[0057] Preferably, the first calcination is performed at a temperature of 400 to 600 °C; for example, it can be 400 °C, 420 °C, 450 °C, 480 °C, 500 °C, 520 °C, 550 °C, 580 °C or 600 °C.

[0058] Preferably, the first calcination is performed for a time period of 2 to 10 h.

[0059] More preferably, the first calcination time is 3 to 8 hours; for example, it can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0060] Preferably, the atmosphere of the first calcination is air.

[0061] A third aspect of the present invention provides a Fischer-Tropsch synthesis catalyst, which comprises the above-mentioned composite catalyst carrier, an active metal and a metal promoter.

[0062] Preferably, the active metal is any one or more selected from iron, cobalt, and ruthenium.

[0063] Preferably, the metal promoter is any one or more selected from lithium, sodium, potassium, rubidium, cesium, calcium, magnesium, cerium, barium, copper and manganese.

[0064] Preferably, the content of the active metal is 0.5 to 10 wt% based on the total weight of the catalyst; for example, it can be 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt% or 10 wt%.

[0065] Preferably, the mass ratio of the active metal to the metal additive is 1:(0.1-2); for example, it can be 1:0.1, 1:0.5, 1:1, 1:1.5 or 1:2.

[0066] The fourth aspect of the present invention provides a method for preparing a Fischer-Tropsch synthesis catalyst, which comprises: dissolving soluble salts corresponding to active metals and metal additives in a solvent to obtain a mixed salt solution, immersing the above-mentioned composite catalyst carrier in the mixed salt solution, and performing a second drying and a second calcination to obtain a Fischer-Tropsch synthesis catalyst.

[0067] Preferably, the composite catalyst carrier is cylindrical.

[0068] Further preferably, the composite catalyst carrier has a length of 3 to 6 mm and a diameter of 1 to 2 mm.

[0069] More preferably, the length of the composite catalyst carrier may be 3 mm, 4 mm, 5 mm or 6 mm.

[0070] More preferably, the diameter of the composite catalyst support may be 1 mm, 1.2 mm, 1.5 mm or 2 mm.

[0071] Preferably, the soluble salt corresponding to the active metal is any one or more selected from nitrate, chloride, acetylacetonate, and acetate.

[0072] Preferably, the soluble salt corresponding to the metal additive is any one or more selected from carbonates, nitrates, chlorides, fluorides, sulfates and acetates.

[0073] Preferably, the solvent is any one or two selected from water and ethanol.

[0074] Preferably, the immersion time is 0.5 to 5 hours.

[0075] Preferably, the second drying temperature is 20-180°C.

[0076] Further preferably, the second drying temperature is 20-150°C; for example, it can be 20°C, 25°C, 30°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C.

[0077] Preferably, the second drying time is 10 to 33 hours.

[0078] Further preferably, the second drying time is 20 to 33 hours; for example, it can be 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours or 33 hours.

[0079] More preferably, the second drying is programmed temperature drying, specifically comprising:

[0080] 1) Dry at 20-30°C for 8-15 hours;

[0081] 2) Dry at 35-50°C for 4-6 hours;

[0082] 3) Dry at 70-90°C for 4-6 hours;

[0083] 4) Dry at 100-120°C for 4-6 hours.

[0084] Preferably, the temperature of the second calcination is 100-400°C; for example, it can be 100°C, 120°C, 150°C, 180°C, 200°C, 220°C, 250°C, 280°C, 300°C, 320°C, 350°C, 380°C or 400°C.

[0085] Preferably, the second calcination time is 2 to 10 hours.

[0086] More preferably, the second calcination time is 3 to 8 hours; for example, it can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0087] More preferably, the second calcination is performed by temperature programming.

[0088] More preferably, the programmed temperature rising is gradually rising from 20-30℃ to 400℃ at a temperature rising rate of 0.5-2℃ / min.

[0089] More preferably, the programmed temperature rising further comprises calcining at 100-150℃ for 0.5-1.5h.

[0090] More preferably, the programmed temperature rising further comprises calcining at 160-200℃ for 0.5-1.5h.

[0091] More preferably, the programmed temperature rising further comprises calcining at 250-350℃ for 0.5-1.5h.

[0092] Preferably, the atmosphere of the second calcining is air.

[0093] The fifth aspect of the present application provides a use of the Fischer-Tropsch synthesis catalyst in a Fischer-Tropsch synthesis reaction.

[0094] As described above, the composite catalyst carrier, its preparation method and use of the present application have the following beneficial effects:

[0095] 1. The composite catalyst carrier of the present application exhibits surface uniformity, high mechanical strength, large specific surface area, excellent heat transfer performance and rich pore structure.

[0096] 2. The preparation method of the composite catalyst carrier of the present application is simple, low in cost and good in repeatability, and is suitable for large-scale industrial production.

[0097] 3. The catalyst prepared from the composite catalyst carrier of the present application exhibits excellent catalytic activity and olefin selectivity in the Fischer-Tropsch synthesis reaction, and has high mechanical strength and is not easy to break. BRIEF DESCRIPTION OF DRAWINGS

[0098] Figure 1 The surface morphology of the composite catalyst carrier prepared in Example 1 of the present application is shown.

[0099] Figure 2 The cross-sectional morphology of the composite catalyst carrier prepared in Example 1 of the present application is shown.

[0100] Figure 3 The partial enlarged view of the cross-sectional morphology of the composite catalyst carrier prepared in Example 1 of the present application is shown.

[0101] Figure 4 The surface morphology of the composite catalyst carrier prepared in Example 2 of the present application is shown.

[0102] Figure 5 The cross-sectional morphology of the composite catalyst carrier prepared in Example 2 of the present application is shown.

[0103] Figure 6 Shown is a partially enlarged view of the cross-sectional morphology of the composite catalyst support prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0104] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0105] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0106] Furthermore, it should be understood that the one or more method steps mentioned in the present invention do not exclude the presence of other method steps before or after the combination step, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified. It should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the presence of other devices / apparatuses before or after the combination device / apparatus, or the insertion of other devices / apparatuses between two explicitly mentioned devices / apparatuses. Furthermore, unless otherwise specified, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be considered within the scope of the present invention.

[0107] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific specific embodiments rather than for limiting the scope of protection of the present invention; in the present specification and claims, unless otherwise expressly stated herein, the singular forms "a", "an" and "the" include plural forms.

[0108] When the embodiments provide numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any numerical value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the embodiments, according to the understanding of the prior art by those skilled in the art and the description of the present invention, any methods, equipment, and materials of the prior art similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention may also be used to implement the present invention.

[0109] Example 1

[0110] This embodiment 1 provides a specific composite catalyst carrier, and the specific preparation method is as follows:

[0111] Preparation of composite carrier powder: Silica, starch and sesbania powder (KF25) were mixed in a mass ratio of 87:10:3 and ball milled using a ball mill to make them evenly mixed. Subsequently, carbon fibers with a length of 5 μm and a diameter of 150 nm (purchased from Jiacai Technology) that accounted for 5% of the mass of silica and carbon fibers with a length of 2 mm that accounted for 5% of the mass of silica were added, and the mixture was evenly mixed by mechanical stirring to obtain a composite carrier powder.

[0112] Preparation of silica sol solution: dissolve neutral silica sol in water to prepare an aqueous solution with a silica sol content of 20%.

[0113] A silica sol solution (2.1 times the mass of the composite support powder) was mixed with the composite support powder using a kneader to form a plastomer. The plastomer was then processed into a 1.5 mm φ cylindrical wet molded body via extrusion. The body was then dried at room temperature for 12 hours, then dried at 40°C for 5 hours, 80°C for 5 hours, and 120°C for 5 hours, and finally calcined at 600°C for 5 hours to produce a strip-shaped composite catalyst support.

[0114] Example 2

[0115] This embodiment 2 provides a specific composite catalyst carrier, and the specific preparation method is as follows:

[0116] Preparation of composite carrier powder: Silica, starch and sesbania powder are mixed in a mass ratio of 87:10:3 and ball milled using a ball mill to mix them evenly. Then, carbon fibers with a length of 500 nm and a diameter of 150 nm (purchased from Jiacai Technology) that are 5% by mass of silica and carbon fibers with a length of 4 mm that are 5% by mass of silica are added, and the mixture is evenly mixed by mechanical stirring to obtain a composite carrier powder.

[0117] Preparation of silica sol solution: dissolve neutral silica sol in water to prepare an aqueous solution with a silica sol content of 30%.

[0118] The composite carrier powder is kneaded with the silica sol solution of 2.1 times the mass of the composite carrier powder to form a plastic body. The plastic body is processed into a cylindrical wet formed body of φ 1.5 mm by an extrusion molding process, dried at room temperature for 12 h, dried at 40°C for 5 h, dried at 80°C for 5 h, dried at 120°C for 5 h, and then calcined at 600°C for 5 h to finally obtain a strip-shaped composite catalyst carrier.

[0119] Example 3

[0120] This example 3 provides a specific composite catalyst carrier, and the specific preparation method is as follows:

[0121] Preparation of the composite carrier powder: silica, starch, and sesbania powder are mixed in a mass ratio of 87:8:5, and ball milling is performed using a ball mill to uniformly mix them. Then, carbon fibers of 10% of the mass of silica, 10 μm in length, and 150 nm in diameter, and carbon fibers of 10% of the mass of silica, 8 mm in length, and 7 μm in diameter, are added, and uniformly mixed by mechanical stirring to obtain the composite carrier powder.

[0122] Preparation of the silica sol solution: a neutral silica sol is dissolved in water to prepare a water solution with a silica sol content of 30%.

[0123] The composite carrier powder is kneaded with the silica sol solution of 2.1 times the mass of the composite carrier powder to form a plastic body. The plastic body is processed into a cylindrical wet formed body of φ 1.5 mm by an extrusion molding process, dried at room temperature for 12 h, dried at 40°C for 5 h, dried at 80°C for 5 h, dried at 120°C for 5 h, and then calcined at 600°C for 5 h to finally obtain a strip-shaped composite catalyst carrier.

[0124] Example 4

[0125] This example 4 provides a specific composite catalyst carrier, and the specific preparation method is as follows:

[0126] Preparation of the composite carrier powder: silica, starch, and sesbania powder are mixed in a mass ratio of 87:8:5, and ball milling is performed using a ball mill to uniformly mix them. Then, carbon fibers of 15% of the mass of silica, 2 mm in length, and 7 μm in diameter, are added, and uniformly mixed by mechanical stirring to obtain the composite carrier powder.

[0127] Preparation of the silica sol solution: a neutral silica sol is dissolved in water to prepare a water solution with a silica sol content of 30%.

[0128] A silica sol solution (2.1 times the mass of the composite support powder) was mixed with the composite support powder using a kneader to form a plastomer. The plastomer was then processed into a 1.5 mm φ cylindrical wet molded body via extrusion. The body was then dried at room temperature for 12 hours, then dried at 40°C for 5 hours, 80°C for 5 hours, and 120°C for 5 hours, and finally calcined at 600°C for 5 hours to produce a strip-shaped composite catalyst support.

[0129] Example 5

[0130] This embodiment 5 provides a specific composite catalyst carrier, and the specific preparation method is as follows:

[0131] Preparation of composite carrier powder: Silica, starch and sesbania powder were mixed in a mass ratio of 87:8:5 and ball-milled using a ball mill to make them evenly mixed. Then, carbon fibers with a length of 4 mm and a diameter of 7 μm, which accounted for 15% of the mass of silica, were added and evenly mixed by mechanical stirring to obtain a composite carrier powder.

[0132] Preparation of silica sol solution: dissolve neutral silica sol in water to prepare an aqueous solution with a silica sol content of 30%.

[0133] A silica sol solution (2.1 times the mass of the composite support powder) was mixed with the composite support powder using a kneader to form a plastomer. The plastomer was then processed into a 1.5 mm φ cylindrical wet molded body via extrusion. The body was then dried at room temperature for 12 hours, then dried at 40°C for 5 hours, 80°C for 5 hours, and 120°C for 5 hours, and finally calcined at 600°C for 5 hours to produce a strip-shaped composite catalyst support.

[0134] Example 6

[0135] This embodiment 6 provides a specific composite catalyst carrier, and the specific preparation method is as follows:

[0136] Preparation of composite carrier powder: Silica, starch and sesbania powder were mixed in a mass ratio of 87:8:5 and ball-milled using a ball mill to make them evenly mixed. Then, carbon fibers with a length of 8 mm and a diameter of 7 μm, which accounted for 15% of the mass of silica, were added and evenly mixed by mechanical stirring to obtain a composite carrier powder.

[0137] Preparation of silica sol solution: dissolve neutral silica sol in water to prepare an aqueous solution with a silica sol content of 30%.

[0138] The silicon sol solution with 2.1 times the mass of the composite carrier powder is kneaded with the composite carrier powder using a kneader to form a plastic body. The plastic body is processed into a cylindrical wet formed body with a diameter of 1.5 mm through an extrusion molding process, dried at room temperature for 12 h, then dried at 40°C for 5 h, 80°C for 5 h, and 120°C for 5 h, and finally calcined at 600°C for 5 h to obtain a strip-shaped composite catalyst carrier.

[0139] Example 7

[0140] Example 7 provides a specific composite catalyst carrier, and the specific preparation method is as follows:

[0141] Preparation of the composite carrier powder: Silica, starch, and sesbania powder are mixed in a mass ratio of 87:8:5, and a ball mill is used for ball milling treatment to make the mixture uniform. Then, carbon fibers with a length of 2 mm and a diameter of 7 μm are added in an amount of 30% of the mass of the silica, and mechanical stirring is used for uniform mixing to obtain the composite carrier powder.

[0142] Preparation of the silicon sol solution: Neutral silica sol is dissolved in water to prepare an aqueous solution with a silica sol content of 30%.

[0143] The silicon sol solution with 2.1 times the mass of the composite carrier powder is kneaded with the composite carrier powder using a kneader to form a plastic body. The plastic body is processed into a cylindrical wet formed body with a diameter of 1.5 mm through an extrusion molding process, dried at room temperature for 12 h, then dried at 40°C for 5 h, 80°C for 5 h, and 120°C for 5 h, and finally calcined at 600°C for 5 h to obtain a strip-shaped composite catalyst carrier.

[0144] Comparative Example 1

[0145] Comparative Example 1 differs from Example 1 in that Comparative Example 1 does not add carbon fibers and silica sol, but only adds water with 2.3 times the mass of the silica to the composite carrier powder for kneading; the rest of the amounts and the preparation method are the same.

[0146] Comparative Example 2

[0147] Comparative Example 2 differs from Example 1 in that Comparative Example 2 does not add starch and carbon fibers, and the mass ratio of silica to sesbania powder is 96:4; the rest of the amounts and the preparation method are the same.

[0148] Comparative Example 3

[0149] Comparative Example 3 differs from Example 1 in that Comparative Example 3 does not add starch, carbon fibers, and silica sol, but only adds water with 2.3 times the mass of the silica to the composite carrier powder for kneading, and the mass ratio of silica to sesbania powder is 96:4; the rest of the amounts and the preparation method are the same.

[0150] Comparative Example 4

[0151] The difference between Comparative Example 4 and Example 1 is that no carbon fiber is added in Comparative Example 4; the remaining addition amounts and preparation methods are the same.

[0152] Example 8

[0153] This embodiment is to prepare a Fischer-Tropsch synthesis catalyst using the composite catalyst carrier prepared in the above Examples 1 to 7 and Comparative Examples 1 to 4. The specific preparation method is as follows:

[0154] 1) The composite catalyst carrier prepared above was crushed into cylindrical granular carriers with a length of 3 to 6 mm and a diameter of 1.5 mm for subsequent metal loading.

[0155] 2) According to the mass ratio of Ru:Na:SiO2 of 0.5:2:98.5, ruthenium nitrosyl nitrate and sodium nitrate were weighed and dispersed in water. The amount of water added was 1 times the mass of the above-mentioned composite catalyst support. After stirring for 2 hours, an equal volume was impregnated on the above-mentioned support. Dry at room temperature for 12 hours, then dry at 40°C for 5 hours, 80°C for 5 hours, and 120°C for 5 hours, and then calcined by programmed temperature rising. The starting temperature was 25°C, and then gradually heated to 400°C at 1°C / min. The calcination was carried out at 120°C, 180°C, and 300°C for 1 hour each to finally obtain a Fischer-Tropsch synthesis catalyst.

[0156] Example 9

[0157] This example tests the surface morphology, specific surface area, and lateral pressure resistance of the composite catalyst supports prepared in Examples 1 to 7 and Comparative Examples 1 to 4, and the catalytic performance of the Fischer-Tropsch synthesis catalyst prepared in Example 8. The specific test results are shown in Table 1.

[0158] First, through naked eye observation, the surfaces of the carriers prepared in Examples 1 to 7 were smooth and glossy, and had good uniformity.

[0159] The morphology of the carrier was further observed using a scanning electron microscope. The morphology of the carrier prepared in Example 1 was as follows: Figures 1 to 3 As shown, Figure 1 For its surface morphology, Figure 2 Its cross-sectional morphology, Figure 3 is a partial enlarged view of its cross-sectional morphology; the morphology of the carrier prepared in Example 2 is as follows Figures 4-6 As shown, Figure 4 For its surface morphology, Figure 5 Its cross-sectional morphology, Figure 6 It is a partial enlarged view of its cross-sectional morphology; according to Figure 1 and Figure 4 The morphology shows that the surface of the carrier prepared in Examples 1 and 2 is uniform. Figure 3and Figure 6 From the morphology, it can be seen that the carriers prepared in Examples 1 and 2 have rich pore structures.

[0160] The test method for lateral compressive strength is as follows:

[0161] Place a formed cylindrical catalyst support on its side on the test platform of the particle strength tester. Apply lateral pressure to the particle. As the pressure increases, the pressure on the particle gradually increases. When the pressure reaches its maximum, the particle is crushed, followed by a sharp drop in pressure, and the test concludes. Record the maximum pressure value, F (N), and measure the column height, L (cm), of the cylindrical particle. The lateral pressure strength, f, is calculated using the formula: f = F / L. Test at least 30 catalyst particles to determine the lateral pressure strength, and take the average value.

[0162] The test method for specific surface area is as follows:

[0163] In a vacuum environment, impurities (such as water vapor and organic matter) on the sample surface are removed by heating (100-300°C) to ensure a clean surface. Using nitrogen as the adsorbate, the gas adsorption capacity (V, converted to standard volume) is measured at different relative pressures (P / P0, ranging from 0.05-0.3) at liquid nitrogen temperature (77K). Based on the relationship between adsorption capacity and relative pressure, the BET equation is used to calculate the monolayer saturation adsorption capacity, and thus the specific surface area.

[0164] BET equation:

[0165] V: adsorption capacity under equilibrium pressure P; V m : saturated adsorption capacity of monolayer; P0: saturated vapor pressure; C: constant related to adsorption heat.

[0166] Specific surface area calculation:

[0167] N A is Avogadro's constant, σ is the cross-sectional area of ​​N2 molecules (0.162nm 2 ), m is the sample mass.

[0168] Through right Graph the straight line and find V from the slope and intercept. m , substituting into the above formula we can get the specific surface area.

[0169] The specific test methods for each catalyst performance are as follows:

[0170] The catalysts prepared above were reduced in H2 at 350°C and atmospheric pressure for 5 h at a reduction space velocity of 8000 h -1After the reduction is completed, the temperature is lowered to 180°C. A mixture of H2 / CO with a volume ratio of 2:1 is introduced as the reaction gas, the temperature is raised to 250°C, the reaction pressure is 5 bar, and the reaction space velocity is 2000h -1 , the direct conversion of synthesis gas to olefins was carried out, and the catalytic results are shown in Table 1.

[0171] Table 1 Specific surface area, lateral pressure resistance and catalytic performance data of composite catalyst carrier

[0172]

[0173] In Table 1, the CO conversion rate is calculated based on the number of carbon atoms, and the calculation formula is as follows:

[0174]

[0175] Among them, CO inlet and CO outlet represent the molar number of CO entering / leaving the reaction system, respectively.

[0176] The formula for calculating carbon dioxide selectivity is:

[0177]

[0178] Among them, CO 2outlet Represents the number of moles of CO2 flowing out of the reaction tube.

[0179] The formula for calculating the selectivity of methane and olefins is similar to that for calculating the selectivity of CO2. 2outlet is replaced by the number of moles of methane or olefin flowing out of the reaction tube.

[0180] According to the data in Table 1, it can be seen that the lateral compressive strength of the carriers prepared in Examples 1 to 7 is above 80 N / cm, which proves that they have strong compressive resistance. The specific surface area of ​​the carriers is greater than 300 m 2 / g, having a large specific surface area; the carrier prepared in Examples 1 to 7 was further prepared into a Fischer-Tropsch synthesis catalyst, which exhibited excellent catalytic performance in the Fischer-Tropsch synthesis reaction: the CO conversion rate was greater than 30%, and the olefin selectivity was greater than 70%.

[0181] Compared with Examples 1 to 7, in Example 1, no carbon fiber and silica sol were added, and the strength and specific surface area of ​​the carrier were significantly reduced; and the catalytic activity and olefin selectivity of the catalyst were reduced; in Examples 2 and 3, no starch was added, so the pore structure of the carrier was less, resulting in a significant reduction in the specific surface area of ​​the carrier, which was not conducive to the diffusion of synthesis gas in the Fischer-Tropsch synthesis reaction, thereby resulting in an increase in the selectivity of methane and carbon dioxide by-products during the reaction, and a significant decrease in the olefin selectivity; in addition, it can be seen from the lateral pressure strength of Examples 2 and 3 that: after the addition of silica sol, the lateral pressure strength of Example 2 was improved to a certain extent, but since no carbon fiber was added, the lateral pressure strength of the carrier was still significantly lower than that of Examples 1 to 7; in Example 4, no carbon fiber was added, and the lateral pressure strength of the carrier was significantly reduced. In addition, since no carbon fiber was added, the heat transfer effect of the carrier was poor, the temperature distribution was uneven during the reaction, and the local temperature would rise, thereby resulting in a significant decrease in the olefin selectivity of the catalyst in the Fischer-Tropsch synthesis reaction.

[0182] In summary, the present application enriches the pore structure of the carrier by adding pore-forming agents, thereby increasing the specific surface area of ​​the carrier, promoting the diffusion of synthesis gas and the desorption of long-chain unsaturated hydrocarbons in the Fischer-Tropsch synthesis reaction, thereby significantly improving the product selectivity of the catalyst; by adding carbon fiber and silica sol, the mechanical strength and heat transfer effect of the carrier are significantly improved, which is conducive to the stable progress of subsequent catalytic reactions; thus, the composite catalyst carrier and its catalyst prepared in the present application can effectively solve the problems of carrier breakage, low mass transfer / heat transfer efficiency, and low olefin selectivity caused by high-pressure reactions in Fischer-Tropsch synthesis, and are suitable for direct conversion of synthesis gas to produce high-value-added hydrocarbons (such as olefins and alkanes), and have important industrial significance in the fields of coal-to-oil and natural gas-to-oil.

[0183] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form or substance. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention. Any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the spirit and scope of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A composite catalyst carrier, characterized in that The composite catalyst support comprises the following raw material components in parts by weight: 80-100 parts by weight of silicon dioxide; 5 to 15 parts by weight of a pore-forming agent; 2 to 10 parts by weight of extrusion aid; 8 to 30 parts by weight of carbon fiber; 9.5 to 140 parts by weight of binder 2. The composite catalyst carrier according to claim 1, characterized in that The pore-forming agent is any one or more selected from starch, cellulose, chitosan, and lignin; and / or the extrusion aid is sesbania powder; and / or the length of the carbon fiber is 500nm to 8mm; and / or the diameter of the carbon fiber is 150nm to 10μm; and / or the particle size of the silica is 10 to 100nm; and / or the binder is any one or more selected from silica sol, aluminum sol, polyvinyl alcohol, carboxymethyl cellulose, and polyethylene glycol.

3. The composite catalyst carrier according to claim 1 or 2, characterized in that The lateral pressure strength of the composite catalyst carrier is 60 to 180 N / cm; and / or the specific surface area of ​​the composite catalyst carrier is greater than 300 m 2 / g.

4. A method for preparing a composite catalyst carrier according to any one of claims 1 to 3, characterized in that: The method comprises: mixing silicon dioxide, a pore-forming agent, an extrusion aid and carbon fibers to form a mixture; dissolving a binder in water to form a binder solution; kneading the mixture and the binder solution to form a plastic body; processing the plastic body into a wet-molded body through an extrusion molding process; and subjecting the wet-molded body to a first drying and a first calcination to obtain a composite catalyst carrier.

5. The preparation method according to claim 4, characterized in that Based on the total weight of the mixture, the amount of the binder solution added is 100-300 wt %; and / or the concentration of the binder in the binder solution is 10-30 wt %.

6. The preparation method according to claim 4, characterized in that The first drying temperature is 20-180° C.; and / or, the first drying time is 10-33 hours; and / or, the first calcining temperature is 400-600° C.; and / or, the first calcining time is 2-10 hours; and / or, the first calcining atmosphere is air.

7. A Fischer-Tropsch synthesis catalyst, characterized in that The catalyst comprises the composite catalyst carrier according to any one of claims 1 to 3, an active metal and a metal promoter.

8. The Fischer-Tropsch synthesis catalyst according to claim 7, characterized in that The active metal is any one or more selected from iron, cobalt, and ruthenium; and / or the metal promoter is any one or more selected from lithium, sodium, potassium, rubidium, cesium, calcium, magnesium, cerium, barium, copper, and manganese; and / or, based on the total weight of the catalyst, the content of the active metal is 0.5 to 10 wt%; and / or, the mass ratio of the active metal to the metal promoter is 1:(0.1 to 2).

9. A method for preparing a Fischer-Tropsch synthesis catalyst according to claim 7 or 8, characterized in that: The method comprises: dissolving soluble salts corresponding to active metals and metal promoters in a solvent to obtain a mixed salt solution, impregnating the composite catalyst carrier according to any one of claims 1 to 3 in the mixed salt solution, and performing a second drying and a second calcination to obtain a Fischer-Tropsch synthesis catalyst.

10. The preparation method according to claim 9, characterized in that The soluble salt corresponding to the active metal is any one or more selected from nitrates, chlorides, acetylacetonates, and acetates; and / or the soluble salt corresponding to the metal additive is any one or more selected from carbonates, nitrates, chlorides, fluorides, sulfates, and acetates; And / or, the solvent is any one or both selected from water and ethanol; and / or, the immersion time is 0.5 to 5 hours; and / or, the temperature of the second drying is 20 to 180° C.; and / or, the time of the second drying is 10 to 33 hours; and / or, the temperature of the second calcination is 100 to 400° C.; and / or, the time of the second calcination is 2 to 10 hours; and / or, the atmosphere of the second calcination is air.

11. Use of the Fischer-Tropsch synthesis catalyst according to claim 7 or 8 in catalyzing a Fischer-Tropsch synthesis reaction.

Images