Molten iron catalyst and its preparation method and application

Abstract

The present application relates to the technical field of catalyst preparation, and discloses a molten iron catalyst and a preparation method and application thereof, wherein the method comprises the following steps: (1) mixing an iron source, a structural promoter and / or a structural promoter precursor, and then performing high-temperature melting treatment to obtain a catalyst carrier; (2) grinding and screening the catalyst carrier to obtain a finished catalyst carrier; and (3) impregnating the finished catalyst carrier with an impregnation solution containing an electronic promoter precursor, and then drying and calcining to obtain the molten iron catalyst. The preparation method is simple to operate, and the combination of the high-temperature melting method and the impregnation method makes the content of the promoter in the catalyst stable, and improves the activity of the molten iron catalyst.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst preparation, in particular to a molten iron catalyst and a preparation method and application thereof. BACKGROUND

[0002] Currently, under the background of coal upgrading and efficiency improvement, how to improve the added value of products has become a hot research issue. Fischer-Tropsch synthesis refers to the reaction of synthesis gas (CO+H2) to hydrocarbons under the action of a catalyst, and the hydrocarbons can be further processed into liquid fuels. Fischer-Tropsch synthesis reactors include low-temperature fixed bed, low-temperature slurry bed and high-temperature fluidized bed. The reaction temperature of low-temperature reaction is usually 200-260℃, and the product is mainly linear alkanes; the reaction temperature of high-temperature reaction is 280-350℃, and the product contains a high content of olefins, which can be treated to obtain products with high added value. The main Fischer-Tropsch synthesis catalysts used in industry include cobalt-based series and iron-based series. In recent years, due to the high price of cobalt, iron-based Fischer-Tropsch synthesis catalysts have been more widely used. Iron-based Fischer-Tropsch synthesis catalysts are divided into two categories: precipitated iron and molten iron. Compared with precipitated iron, molten iron catalyst has higher mechanical strength, which can meet the requirements of high-temperature fluidized bed. Therefore, under the background of coal upgrading and efficiency improvement, high-temperature molten iron Fischer-Tropsch synthesis is favored by more and more researchers.

[0003] Chinese patent CN1279142C discloses a molten iron Fischer-Tropsch synthesis catalyst with Fe3O4 as the gas phase, and Al2O3, CaO, K2O and SiO2 as the auxiliary catalyst. The catalyst has a low space-time yield, a high CH4 selectivity and a low olefin selectivity. 5+

[0004] Chinese patent application CN101391219A discloses a catalyst prepared from trivalent iron and divalent iron as raw materials, and controlling Fe 3+ / Fe 2+ , and using Al2O3, CaO, K2O, SiO2, MgO and NaO as auxiliary catalysts. The catalyst has a low CH4 selectivity, but a high CO2 selectivity, which is not conducive to carbon emission reduction.

[0005] In addition, during high-temperature smelting, alkali metals and alkaline earth metals will volatilize at high temperature, and the volatilization ratio will change with the smelting temperature and smelting time. During cooling, the alkali metals are prone to segregation, which makes it difficult to control the content of auxiliary elements in the finished catalyst, and the quality of the finished catalyst fluctuates greatly. SUMMARY

[0006] ​The application aims to overcome the problems of the prior art, such as difficulty in controlling the content of auxiliary elements in the molten iron catalytic preparation process, low CO conversion rate, high CH4 selectivity and low olefin selectivity, and provides a molten iron catalyst and a preparation method and application thereof.

[0007] To achieve the above-mentioned purpose, the first aspect of the application provides a preparation method of a molten iron catalyst, wherein the method comprises the following steps:

[0008] (1) mixing an iron source and a structural auxiliary agent and / or a structural auxiliary agent precursor, and then performing high-temperature melting treatment to obtain a catalyst carrier;

[0009] (2) grinding and screening the catalyst carrier to obtain a finished catalyst carrier;

[0010] (3) impregnating and drying and calcining the finished catalyst with an impregnation liquid containing an electronic auxiliary agent precursor to obtain a molten iron catalyst;

[0011] The structural auxiliary agent is SiO2 and optionally Al2O3; and the electronic auxiliary agent comprises at least one of K2O, Na2O, CaO, MgO, MnO and CeO2.

[0012] The content of the iron source, the structural auxiliary agent and the electronic auxiliary agent is such that, in the molten iron catalyst, the content of iron is 30-75 mass%, the content of Fe2O3 is 0-40 g / 100 g Fe, the content of SiO2 is 0.1-40 g / 100 g Fe, the content of Al2O3 is 0-40 g / 100 g Fe, the content of K2O is 0.1-5 g / 100 g Fe, the content of Na2O is 0-5 g / 100 g Fe, the content of CaO is 0-10 g / 100 g Fe, the content of MgO is 0-10 g / 100 g Fe, the content of MnO is 0-15 g / 100 g Fe, and the content of CeO2 is 0-15 g / 100 g Fe. 3+ / Fe 2+ The content of the iron source, the structural auxiliary agent and the electronic auxiliary agent is such that, in the molten iron catalyst, the content of iron is 30-75 mass%, the content of Fe2O3 is 0-40 g / 100 g Fe, the content of SiO2 is 0.1-40 g / 100 g Fe, the content of Al2O3 is 0-40 g / 100 g Fe, the content of K2O is 0.1-5 g / 100 g Fe, the content of Na2O is 0-5 g / 100 g Fe, the content of CaO is 0-10 g / 100 g Fe, the content of MgO is 0-10 g / 100 g Fe, the content of MnO is 0-15 g / 100 g Fe, and the content of CeO2 is 0-15 g / 100 g Fe.

[0013] The second aspect of the application provides a molten iron catalyst prepared by the preparation method of the first aspect.

[0014] The third aspect of the application provides application of the molten iron catalyst prepared by the preparation method of the first aspect in a high-temperature Fischer-Tropsch synthesis reaction.

[0015] The preparation method of the molten iron catalyst provided by the application adopts high-temperature melting method and impregnation method in combination, the promoter is not affected by the melting process, the content of the promoter in the molten iron catalyst is stable, the molten iron catalyst has good activity and stability, and further preferably, the preparation method adopts a grading process (grinding and screening) to screen the particle size of the catalyst, so that the particle size distribution of the catalyst is relatively concentrated; the molten iron catalyst provided by the application is particularly suitable for high-temperature Fischer-Tropsch synthesis reaction, preferably high-temperature fluidized bed reaction, and has the advantages of high CO conversion rate, low CH4 selectivity and high olefin selectivity. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values claimed herein are not to be understood as being limited to the exact values recited as implicitly disclosed by the above description. Ranges can be expressed as from one value and / or to another value. When such ranges are expressed, other disclosed or potential values that are within the range are also encompassed. For values which are less than one or greater than one, "less than or equal to" or "greater than or equal to" the limits of the range is specifically disclosed. For values that are less than one or greater than one, "less than or equal to" or "greater than or equal to" the limit of the range is also specifically disclosed. The same applies to any numbered values that fall within the range.

[0017] The first aspect of the application provides a preparation method of a molten iron catalyst, wherein the method comprises the following steps:

[0018] (1) mixing an iron source and a structural promoter and / or a structural promoter precursor, and then performing high-temperature melting treatment to obtain a catalyst carrier;

[0019] (2) grinding and screening the catalyst carrier to obtain a finished catalyst carrier;

[0020] (3) impregnating and drying and calcining the finished catalyst carrier with an impregnation liquid containing an electronic promoter precursor to obtain a molten iron catalyst;

[0021] The structural promoter is SiO2 and optionally Al2O3; and the electronic promoter comprises at least one of K2O, Na2O, CaO, MgO, MnO and CeO2.

[0022] The amount of the iron source, the structural promoter and the electronic promoter is such that the content of iron in the molten iron catalyst is 30-75% by mass based on the total amount of the molten iron catalyst, and the content of Fe2O3 in the molten iron catalyst is 10-30% by mass based on the total amount of the molten iron catalyst. 3+ / Fe 2+The molar ratio of Fe2O3 to SiO2 is 0.5-5, the content of SiO2 is 0.1-40 g / 100 g Fe, the content of Al2O3 is 0-40 g / 100 g Fe, the content of K2O is 0.1-5 g / 100 g Fe, the content of Na2O is 0-5 g / 100 g Fe, the content of CaO is 0-10 g / 100 g Fe, the content of MgO is 0-10 g / 100 g Fe, the content of MnO is 0-15 g / 100 g Fe, and the content of CeO2 is 0-15 g / 100 g Fe.

[0023] According to the application, preferably, the amount of the iron source, the structural assistant and the electronic assistant is such that the content of iron element in the molten iron catalyst is 50-70 mass% based on the total amount of the molten iron catalyst, the content of Fe 3+ / Fe 2+ The molar ratio of Fe2O3 to SiO2 is 0.5-5, the content of SiO2 is 0.1-40 g / 100 g Fe, the content of Al2O3 is 0-40 g / 100 g Fe, the content of K2O is 0.1-5 g / 100 g Fe, the content of Na2O is 0-5 g / 100 g Fe, the content of CaO is 0-10 g / 100 g Fe, the content of MgO is 0-10 g / 100 g Fe, the content of MnO is 0-15 g / 100 g Fe, and the content of CeO2 is 0-15 g / 100 g Fe.

[0024] According to the method of the application, the molten iron catalyst is prepared by combining high-temperature melting method and impregnation method. The high-temperature melting method is to mix various materials uniformly under high-temperature melting state, which has the advantages of simple operation and low requirement for raw materials. The impregnation method is a process of gradually adsorbing active components on the surface of the carrier by putting the catalyst carrier into the impregnation liquid, which has the advantages of controllable assistant content, stable composition and uniform distribution. The combination of the two methods not only maintains the advantages of simple operation and low requirement for raw materials of the melting method, but also avoids the disadvantages of inaccurate measurement caused by volatilization of components in the melting process and uneven distribution of assistants caused by segregation in the cooling process, greatly improving the reaction performance of the molten iron catalyst.

[0025] In the application, the content of iron element in the molten iron catalyst is measured by X-ray fluorescence spectrometry, Fe 3+ / Fe 2+ The molar amount of the electronic assistant and the structural assistant is measured by coordination titration and redox titration.

[0026] In the present application, the source of each substance in step (1) is not specifically limited. Preferably, the iron source is selected from at least one of magnetite, hematite, reduced iron powder and iron-containing oxide, and more preferably at least one of magnetite, hematite and reduced iron powder. The advantage of using this preferred embodiment is that natural magnetite is widely available and low in price, and the main component is Fe3O4, Fe 3+ / Fe 2+ The amount ratio of the substances is 2:1, and a small amount of hematite or reduced iron powder is added to reduce the cost of the molten iron from the catalyst. 3+ / Fe 2+ The amount ratio of the substances is 2:1, and a small amount of hematite or reduced iron powder is added to reduce the cost of the molten iron from the catalyst.

[0027] In a preferred embodiment, the structural aid precursor is selected from a mineral substance that can be converted into the structural aid by subsequent calcination. The advantage of using this preferred embodiment is that the melting method is the mixing process of materials in a high-temperature molten state, and the raw material requirements are lower. Directly using mineral substances can not only affect the product performance, but also reduce the cost.

[0028] In the present application, the conditions for high-temperature melting treatment in step (1) have a wide selection range, and those skilled in the art can select according to actual needs. Preferably, the melting temperature of the high-temperature melting treatment is 1800-2200°C, and the time is 5-45 min; more preferably, the melting temperature is 2000-2200°C, and the time is 15-30 min. The advantage of using this preferred embodiment is that the specific melting temperature and melting time can not only ensure that the mixed materials are fully melted and uniformly mixed, but also prevent the waste of equipment capacity and energy due to too long melting time, and ensure that the materials are not largely volatilized due to melting.

[0029] In the present application, the high-temperature melting treatment equipment can be selected from conventional melting equipment in the art, such as a vacuum melting furnace. The pressure in the vacuum melting furnace is 0-5×10 -6 MPa in terms of gauge pressure.

[0030] In the present application, before high-temperature melting treatment, inert gas (preferably argon) is preferably introduced to adjust the pressure in the vacuum melting furnace. The pressure is -0.05 to (-0.07) MPa in terms of absolute pressure.

[0031] In a preferred embodiment, step (1) further comprises cooling treatment after high-temperature melting treatment. The cooling temperature is 1-20°C, and the time is 1-15 min. The advantage of using this preferred embodiment is that the specific cooling temperature and cooling time can not only ensure the smooth cooling of the materials, but also prevent the materials from exploding during the cooling process to produce too much unqualified products.

[0032] In the present application, the finished catalyst carrier has good structure parameters. Preferably, in step (2), the specific surface area of the finished catalyst carrier is less than 50 m 2 / g, and the pore volume is less than 45 cm 3 / g, and further preferably, the specific surface area is 0.5-30 m 2 / g, and the pore volume is 0.5-25 cm 3 / g. The advantage of using this preferred embodiment is that when the specific surface area and the pore volume of the obtained finished catalyst carrier are too large, the wear resistance of the finished catalyst carrier is poor, which leads to poor wear resistance of the final fused iron catalyst, and the fused iron catalyst is broken in large quantities when used in a fluidized bed, thereby affecting the reaction performance of the fused iron catalyst. After the specific surface area and the pore volume are optimized, the activity of the fused iron catalyst is ensured while the wear resistance of the fused iron catalyst is also ensured.

[0033] In the present application, the specific surface area and the pore volume of the finished catalyst carrier are measured by the multipoint BET test method.

[0034] In the present application, the finished catalyst carrier is obtained by grinding and screening the catalyst carrier in step (2). Preferably, in step (2), the particle size of the finished catalyst carrier is 15-300 μm, and further preferably, 25-150 μm. The advantage of using this preferred embodiment is that the electronic auxiliary agent is introduced by the impregnation method in the present application, and the impregnation method does not cause a large change in the particle size of the catalyst. Therefore, the particle size of the finished catalyst carrier is basically consistent with the particle size of the fused iron catalyst, and the particle size range of the finished catalyst carrier can ensure that the particle size range of the fused iron catalyst meets the use requirements of the fluidized bed.

[0035] In the present application, the source of the electronic auxiliary agent in step (3) is not specifically limited. Preferably, in step (3), the electronic auxiliary agent precursor is selected from at least one of a carbonate, a nitrate and a chloride, and further preferably, a carbonate and / or a nitrate.

[0036] In the present application, preferably, in step (3), the electronic auxiliary agent precursor is dissolved in water to prepare an impregnation solution. For example, the following method can be used: a certain mass of the catalyst carrier is taken, an excess of deionized water is added, and the catalyst carrier is stored for a period of time to ensure that the inside of the pore channel is completely wetted. After the free water is poured out, the mass is weighed, and the saturated pore volume of the carrier is calculated. A certain mass of the catalyst carrier is weighed again, the total volume of the impregnation solution required is calculated according to the saturated pore volume, and the mass of each electronic auxiliary agent precursor is calculated according to the formula. A certain mass of each electronic auxiliary agent precursor is weighed into a beaker, a certain amount of deionized water is added to completely dissolve it, and after stirring uniformly, it is transferred to a volumetric flask of a certain volume, water is added to the mark, and it is mixed uniformly to obtain an impregnation solution of a specific concentration and a specific volume.

[0037] In a preferred embodiment, the impregnation solution has a solid content of 10-40% by weight.

[0038] In the present application, the conventional impregnation method in the art is suitable for the present application, for example, it can be equal-volume impregnation, or co-impregnation, and preferably equal-volume impregnation. Specifically, the finished catalyst carrier in step (3) is impregnated in the impregnation solution containing the electronic auxiliary agent precursor until the impregnation solution is completely absorbed.

[0039] In the present application, the drying condition in step (3) is not specifically limited. Preferably, the temperature rising rate is 0.5-5 ℃ / min, the temperature is 80-140 ℃, and the time is 2-6 h, and further preferably, the temperature rising rate is 1-3 ℃ / min, the temperature is 100-120 ℃, and the time is 3-4 h. The advantage of using this preferred embodiment is that this drying procedure can ensure that the speed of water migration from the inside of the catalyst pores to the surface of the catalyst is consistent with the speed of water migration from the surface of the catalyst to the atmosphere, so that the drying effect can be achieved without breaking the catalyst, and segregation phenomenon is avoided.

[0040] In the present application, the calcination condition in step (3) is not specifically limited. Preferably, the temperature rising rate is 1-6 ℃ / min, the calcination temperature is 500-700 ℃, and the time is 2-6 h, and further preferably, the temperature rising rate is 2-4 ℃ / min, the calcination temperature is 550-650 ℃, and the time is 3-4 h. The advantage of using this preferred embodiment is that this calcination procedure can ensure that the active component required for the reaction and the surface area and pore volume of the catalyst are obtained, and at the same time, the appropriate calcination temperature and calcination time are selected to make the catalyst have good stability.

[0041] The second aspect of the present application provides a fused iron catalyst prepared by the preparation method of the first aspect.

[0042] In a preferred embodiment, the fused iron catalyst contains iron elements, structural auxiliary agents, and electronic auxiliary agents, and the content of iron elements is 30-75% by mass based on the total amount of the fused iron catalyst, Fe 3+ / Fe 2+The molar ratio of Fe / Al2O3 is 0.5-5; the structural assistant agent comprises SiO2 and optionally Al2O3, and the content of SiO2 is 0.1-40 g / 100 g Fe, and the content of Al2O3 is 0-40 g / 100 g Fe; the electronic assistant agent comprises at least one of K2O, Na2O, CaO, MgO, MnO and CeO2, and the content of K2O is 0.1-5 g / 100 g Fe, the content of Na2O is 0-5 g / 100 g Fe, the content of CaO is 0-10 g / 100 g Fe, the content of MgO is 0-10 g / 100 g Fe, the content of MnO is 0-15 g / 100 g Fe, and the content of CeO2 is 0-15 g / 100 g Fe.

[0043] In a particularly preferred embodiment, the content of Fe element is 50-70% by mass based on the total amount of the molten iron catalyst, and the content of Fe 3+ / Fe 2+ is 1-3, the content of SiO2 is 1-20 g / 100 g Fe, the content of Al2O3 is 1-20 g / 100 g Fe, the content of K2O is 0.1-3 g / 100 g Fe, the content of Na2O is 0-3 g / 100 g Fe, the content of CaO is 0-5 g / 100 g Fe, the content of MgO is 0-5 g / 100 g Fe, the content of MnO is 0-5 g / 100 g Fe, and the content of CeO2 is 0-5 g / 100 g Fe.

[0044] Preferably, the specific surface area of the molten iron catalyst is 0.5-50 m 2 / g, the pore volume is 0.5-45 cm 3 / g, and the particle size is 0-300 μm. Further preferably, the specific surface area of the molten iron catalyst is 0.5-30 m 2 / g, the pore volume is 0.5-25 cm 3 / g, and the particle size is 25-150 μm.

[0045] The molten iron catalyst provided by the application is particularly suitable for high-temperature Fischer-Tropsch synthesis reaction, and has the advantages of high CO conversion rate, low CH4 selectivity and high olefin selectivity.

[0046] The third aspect of the application provides the application of the molten iron catalyst prepared by the preparation method of the first aspect in high-temperature Fischer-Tropsch synthesis reaction.

[0047] According to the present application, preferably, a high-temperature fluidized bed reactor is used, and the high-temperature Fischer-Tropsch synthesis reaction conditions include a reaction temperature of 300-550℃, a reaction pressure of 1-3 MPa, a H2 / CO molar ratio of 2-6:1, a CO2 / CO molar ratio of 0-4:1, and a mixed gas space velocity of 5000-50000 ml / (g·h); further preferably, the reaction temperature is 320-340℃, the reaction pressure is 2-2.5 MPa, the H2 / CO molar ratio is 2-4:1, the CO2 / CO molar ratio is 0-2:1, and the mixed gas space velocity is 20000-40000 ml / (g·h). The preferred embodiment has the advantage that the reaction conditions maximize the production capacity of a single set of equipment while taking into account the optimal operating temperature of the molten iron catalyst, the fluidization requirements of the fluidized bed, and the limitations of the abrasion resistance of the catalyst.

[0048] In the present application, the catalyst needs to be activated before the high-temperature Fischer-Tropsch synthesis reaction. Preferably, the activation treatment conditions are a temperature of 400-450℃, a pressure of 1-2 MPa, and a time of 2-6 h; further preferably, the temperature is 420-430℃, the pressure is 1-1.5 MPa, and the time is 4-6 h.

[0049] In the present application, preferably, hydrogen is used to activate the catalyst. Preferably, the space velocity is 100-1000 ml / (g·h). The preferred embodiment has the advantage that the catalyst activated under the conditions has the most complete activation, the most active sites, and the best catalyst activity.

[0050] The present application will be described in detail below through examples. In the following examples, the raw materials are all commercially available unless otherwise specified.

[0051] Example 1

[0052] 96 g of magnetite powder, 12.5 g of hematite powder, 3.4 g of Al2O3 powder, and 3.2 g of SiO2 powder were mixed in a mixer, pressed into a tablet in a tablet press, and then transferred into a vacuum melting furnace. The vacuum was drawn to 5 Pa (gauge pressure), and argon was then introduced to -0.05 MPa (absolute pressure). The above operation was repeated three times, and then the melting operation was performed at 2000℃ for 30 min. After the melting was completed, cooling water at 15℃ was introduced into the interlayer around the tray to rapidly cool the material to below 20℃, and the cooling time was 10 min. After the cooling was completed, the communication valve was opened, and the material was taken out of the melting furnace after the pressure in the furnace returned to normal pressure. The material was first coarsely broken in a crusher, then finely ground in a mortar, and then sieved on an automatic sieve machine to obtain 101.2 g of finished catalyst carrier with a particle size of 25-150 μm. The finished catalyst carrier had a BET specific surface area of 16.3 m2 / g and a pore volume of 1.72 cm3 / g. 2 / g, pore volume 1.72 cm3 Take 90 g of the 100 g, and place it in a beaker. Take another beaker, and weigh the following materials: K2CO3, 1.8 g; Ca(NO3)2: 2.1 g; Mg(NO3)2: 1.6 g; NaNO3: 4.3 g; Mn(NO3)2: 1.0 g; Ce(NO3)3·9H2O: 8.0 g; add 80 mL of water to completely dissolve, and then dilute to 160 mL of mixed solution, with a solid content of 11.5 wt%. Add the mixed solution to the beaker containing the finished catalyst carrier, and shake the beaker constantly, so that the finished catalyst carrier fully absorbs the solution, with an impregnation time of 0.5 h. After impregnation is complete, lay the finished catalyst carrier flat in a tray, and heat at a rate of 1 ℃ / min to 120 ℃, dry for 4 h, and then cool to room temperature, and transfer to a calcination furnace, heat at a rate of no more than 3 ℃ / min to 600 ℃, and keep the temperature for 4 h, after which calcination is complete, cool to room temperature, and remove, and the fused iron catalyst is prepared. Analyze the content of each substance in the fused iron catalyst, and the results are shown in Table 1, and analyze the structural parameters of the fused iron catalyst, and the results are shown in Table 2.

[0053] The performance of the catalyst is evaluated using a fluidized bed reactor. Before performance evaluation, the catalyst is activated using hydrogen, with activation conditions of: a temperature of 420 ℃, a pressure of 1 MPa, a time of 4 h, and a space velocity of 1000 ml / (g·h); and performance evaluation conditions of: a temperature of 320 ℃, a pressure of 2.2 MPa, a H2 / CO molar ratio of 4, a CO / CO2 molar ratio of 1.5, and a mixed gas space velocity of 20000 ml / (g·h). The gas flow is controlled by a Brooks flowmeter, and the reaction products successively pass through a hot trap, a cold trap, and then the non-condensed components are discharged into a system and analyzed online by a gas chromatograph GC7890 (Agilent) at regular time intervals. The cold trap products are separated into oil and water, mixed with the hot trap products, and analyzed offline in a gas chromatograph. The performance indicators of the fused iron catalyst are calculated based on the analysis results, and are shown in Table 3.

[0054] Example 2

[0055] The fused iron catalyst is prepared in the same manner as in Example 1, except that the amount of the electronic auxiliary agent is changed, and the materials for preparing the solution are changed to: K2CO3: 2.2 g; Ca(NO3)2: 1.4 g; Mg(NO3)2: 0.9 g; NaNO3: 5.1 g; Mn(NO3)2: 1.2 g; Ce(NO3)3·9H2O: 8.8 g, and other conditions are the same as in Example 1. The content of each substance in the fused iron catalyst is analyzed, and the results are shown in Table 1, and the structural parameters of the fused iron catalyst are analyzed, and the results are shown in Table 2.

[0056] The performance evaluation test conditions are the same as in Example 1, and the performance indicators of the fused iron catalyst are shown in Table 3.

[0057] Example 3

[0058] 102 g of magnetite powder, 2.3 g of reduced iron powder, 5.3 g of Al2O3 powder and 4.1 g of SiO2 powder were mixed well in a mixer, and the finished catalyst carrier was prepared according to the same method as in Example 1. The specific surface area of the finished catalyst carrier was 15.4 m2 / g, and the pore volume was 1.61 cm3 / g. The same solution as in Example 1 was prepared (the total volume of the solution was changed from 160 mL to 145 mL), and the impregnation, drying and calcination processes of the finished catalyst carrier were completed according to the same method as in Example 1, to obtain the molten iron catalyst of Example 3. The content of each substance in the molten iron catalyst was analyzed, and the results are shown in Table 1. The structural parameters of the molten iron catalyst were analyzed, and the results are shown in Table 2. 2 3 The test conditions for performance evaluation were the same as in Example 1. The performance indicators of the molten iron catalyst are shown in Table 3.

[0059] The test conditions for performance evaluation were the same as in Example 1. The performance indicators of the molten iron catalyst are shown in Table 3.

[0060] Example 4

[0061] The finished catalyst carrier was prepared according to the same material ratio and the same preparation method as in Example 3, and then the same solution as in Example 2 was prepared (the total volume of the solution was changed from 160 mL to 145 mL). The impregnation, drying and calcination processes of the finished catalyst carrier were completed according to the same method as in Example 2, to obtain the molten iron catalyst of Example 4. The content of each substance in the molten iron catalyst was analyzed, and the results are shown in Table 1. The structural parameters of the molten iron catalyst were analyzed, and the results are shown in Table 2.

[0062] The test conditions for performance evaluation were the same as in Example 1. The performance indicators of the molten iron catalyst are shown in Table 3.

[0063] Example 5

[0064] 96 g of magnetite powder, 12.5 g of hematite powder, 3.4 g of Al2O3 powder and 3.2 g of SiO2 powder were mixed according to the material ratio of Example 1, and then the melting operation was performed at 2600°C for 30 min according to the method of Example 1. The impregnation solution was prepared according to the same preparation method as in Example 1, and the preparation of the molten iron catalyst was completed. The content of each substance in the molten iron catalyst was analyzed, and the results are shown in Table 1. The structural parameters of the molten iron catalyst were analyzed, and the results are shown in Table 2.

[0065] The test conditions for performance evaluation were the same as in Example 1. The performance indicators of the molten iron catalyst are shown in Table 3.

[0066] Comparative Example 1

[0067] ​According to the material ratio of Example 1, 96 g of magnetite powder, 12.5 g of hematite powder and 3.4 g of Al2O3 powder, 3.2 g of SiO2 powder, K2CO3, 2.3 g; Ca(NO3)2: 2.7 g; Mg(NO3)2: 2.05 g; NaNO3: 5.5 g; Mn(NO3)2: 1.3 g; Ce(NO3)3·9H2O: 10.2 g were mixed in a mixer, and after tabletting in a tabletting machine, they were transferred into a vacuum melting furnace. The fused iron catalyst was prepared according to the same method as in Example 1. The content of each substance in the fused iron catalyst was analyzed, and the results are shown in Table 1. The structural parameters of the fused iron catalyst were analyzed, and the results are shown in Table 2.

[0068] The performance evaluation test conditions were the same as in Example 1. The performance indicators of the fused iron catalyst are shown in Table 3.

[0069] Comparative Example 2

[0070] The catalyst carrier was prepared according to the same method as in Example 1. The amount of the electronic auxiliary agent was changed. The amount of K2CO3 was changed from 1.8 g to 18 g, and the amounts of the other electronic auxiliary agents remained unchanged. The other conditions were the same as in Example 1. The content of each substance in the fused iron catalyst was analyzed, and the results are shown in Table 1. The structural parameters of the fused iron catalyst were analyzed, and the results are shown in Table 2.

[0071] The performance evaluation test conditions were the same as in Example 1. The performance indicators of the fused iron catalyst are shown in Table 3.

[0072] Comparative Example 3

[0073] According to the same method as in Example 1, the material ratio was changed. The amount of SiO2 powder was changed from 3.2 g to 40 g. The other conditions were the same as in Example 1. The content of each substance in the fused iron catalyst was analyzed, and the results are shown in Table 1. The structural parameters of the fused iron catalyst were analyzed, and the results are shown in Table 2.

[0074] The performance evaluation test conditions were the same as in Example 1. The performance indicators of the fused iron catalyst are shown in Table 3.

[0075] Table 1 Content of each substance in the fused iron catalyst in Examples 1-5 and Comparative Examples 1-3

[0076]

[0077]

[0078] Note: In Table 1, the content of the structural auxiliary agent and the electronic auxiliary agent is relative to 100 g of iron in the fused iron catalyst.

[0079] Table 2 Structural parameters of finished catalyst carriers and molten iron catalysts in Examples 1-5 and Comparative Examples 1-3

[0080]

[0081] Table 3 Performance test indexes of molten iron catalysts in Examples 1-5 and Comparative Examples 1-3

[0082]

[0083]

[0084] As can be seen from the results in Table 3, the molten iron catalysts prepared in Examples 1 and 2 using the method of combining the melting method and the impregnation method of the present application have better reaction activity and target product selectivity than Comparative Example 1, and have obviously better effects.

[0085] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for preparing a molten iron catalyst, wherein, The method includes the following steps: (1) The iron source and structural additives and / or structural additive precursors are mixed and subjected to high-temperature melting treatment to obtain a catalyst support; the melting temperature of the high-temperature melting treatment is 1800-2200℃ and the time is 5-45min. (2) Grind and sieve the catalyst support to obtain the finished catalyst support; (3) The finished catalyst support is impregnated with an impregnation solution containing an electronic auxiliary precursor and then dried and calcined to obtain a molten iron catalyst; The structural additives are SiO2 and Al2O3; the electronic additives include K2O, Na2O, CaO, MgO, MnO and CeO2. The amounts of the iron source, structural additives, and electronic additives used are such that, based on the total amount of the molten iron catalyst, the iron content is 50-70% by mass, Fe. 3+ / Fe 2+ The molar ratio of the components is 1-3, the content of SiO2 is 3.83-20g / 100gFe, the content of Al2O3 is 4.06-20g / 100gFe, the content of K2O is 1.25-3g / 100gFe, the content of Na2O is 2.16-3g / 100gFe, the content of CaO is 0.73-5g / 100gFe, the content of MgO is 0.04-5g / 100gFe, the content of MnO is 0.47-5g / 100gFe, and the content of CeO2 is 2.46-5g / 100gFe.

2. The preparation method according to claim 1, wherein, In step (1), the iron source is selected from at least one of magnetite, hematite, reduced iron powder and iron oxide.

3. The preparation method according to claim 1, wherein, In step (1), the structural additive precursor is selected from minerals that can be converted into the structural additive through subsequent calcination.

4. The preparation method according to claim 1, wherein, Step (1) also includes cooling after high-temperature melting treatment, with a cooling temperature of 1-20℃ and a time of 1-15min.

5. The preparation method according to claim 1, wherein, In step (2), the specific surface area of ​​the finished catalyst support is less than 50 m². 2 / g, pore volume less than 45cm³ 3 / g.

6. The preparation method according to claim 5, wherein, The specific surface area of ​​the finished catalyst support is 0.5-30 m². 2 / g, pore volume 0.5-25cm 3 / g.

7. The preparation method according to claim 1, wherein, In step (2), the particle size of the finished catalyst support is 15-300 μm.

8. The preparation method according to claim 7, wherein, The particle size of the finished catalyst support is 25-150 μm.

9. The preparation method according to claim 1, wherein, In step (3), the electronic auxiliary precursor is selected from at least one of carbonate, nitrate and chloride.

10. The preparation method according to claim 1, wherein, In step (3), the drying heating rate is 0.5-5 / min, the temperature is 80-140℃, and the time is 2-6h.

11. The preparation method according to claim 10, wherein, The drying heating rate is 1-3℃ / min, the temperature is 100-120℃, and the time is 3-4h.

12. The preparation method according to claim 1, wherein, In step (3), the calcination heating rate is 1-6℃ / min, the calcination temperature is 500-700℃, and the time is 2-6h.

13. The preparation method according to claim 12, wherein, The calcination heating rate is 2-4℃ / min, the temperature is 550-650℃, and the time is 3-4h.

14. The molten iron catalyst prepared by any one of claims 1-13.

15. The application of the molten iron catalyst prepared by any one of claims 1-13 in high-temperature Fischer-Tropsch synthesis reaction.

16. The application according to claim 15, wherein, The conditions for high-temperature Fischer-Tropsch synthesis include a reaction temperature of 300-550℃, a reaction pressure of 1-3 MPa, a molar ratio of H2 / CO of 2-6:1, a molar ratio of CO2 / CO of 0-4:1, and a mixed gas space velocity of 5000-50000 ml / (g·h).

Images