Process for the preparation of a fischer-tropsch melt iron catalyst and use thereof

Abstract

The application provides a preparation method of a Fischer-Tropsch synthesis molten iron catalyst, and the method comprises multiple melting operations, and can improve the performance of the Fischer-Tropsch synthesis molten iron catalyst and improve the performance stability of the catalyst between batches.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a Fischer-Tropsch synthesis molten iron catalyst and its application, in particular to a preparation method of a Fischer-Tropsch synthesis molten iron catalyst for fluidized bed and its application. BACKGROUND

[0002] Since the birth of Fischer-Tropsch synthesis technology in the last century, it has been the focus of researchers. Fischer-Tropsch synthesis refers to the reaction of synthesis gas (CO+H2) to produce hydrocarbons under the action of a catalyst, and the hydrocarbons can be further processed into liquid fuels. From the catalyst, Fischer-Tropsch synthesis can be divided into 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 paid more and more attention. From the reactor and reaction conditions, 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 content of olefins in the product is higher, which can be processed to obtain products with higher added value. In order to improve the added value of products and help coal enterprises to improve quality and efficiency, high-temperature iron-based Fischer-Tropsch synthesis is a good choice.

[0003] A Fischer-Tropsch synthesis catalyst with Fe3O4 as the gas phase is disclosed in Chinese patent CN1279142C, Al2O3, CaO, K2O and SiO2 are used as the auxiliary catalyst. The space-time yield of C5+ of the catalyst is too low, the CH4 selectivity is high, and the olefin selectivity is low.

[0004] Chinese patent CN200810202454 uses trivalent iron and divalent iron as raw materials, controls the ratio of Fe 3+ / Fe 2+ , and uses Al2O3, CaO, K2O, SiO2, MgO and NaO as auxiliary catalysts. The catalyst ensures a low CH4 selectivity while the CO2 selectivity is too high, which is not conducive to carbon emission reduction requirements.

[0005] Therefore, it is still a great challenge in the field to develop a Fischer-Tropsch synthesis molten iron catalyst with balanced performance, especially a catalyst with CO conversion rate higher than 90%, CH4 selectivity lower than 10%, the sum of CH4 and CO2 selectivity lower than 20%, and the sum of C2 to C4 olefin selectivity higher than 25%. SUMMARY

[0006] The purpose of the present application is to overcome the defects of the above-mentioned technology, and to develop a preparation method of a Fischer-Tropsch synthesis molten iron catalyst. The Fischer-Tropsch synthesis molten iron catalyst (also referred to as molten iron catalyst in this application) synthesized by the method is suitable for fluidized bed reactor and has good catalytic performance.

[0007] The object of the present application can be achieved by the following technical solutions:

[0008] A preparation method of a Fischer-Tropsch synthesis fused iron catalyst, the preparation method comprising the following steps:

[0009] (1) mixing an iron-containing raw material with SiO2 powder and Al2O3 powder, and optionally, corresponding metal salts of one or more of K, Na, Ca, Mg, Mn and Ce, and then tabletting;

[0010] (2) transferring the obtained mixture tablet to a melting furnace, performing vacuum extraction and argon replacement treatment, and then performing melting treatment at 1800-2200°C, to obtain a melting product, the melting time being 5-15 min; in the present application, it can be understood by those skilled in the art that the vacuum extraction and argon replacement can be repeated one or more times until the argon purity inside the furnace body reaches the preset standard;

[0011] (3) after the melting product is cooled, crushing, grinding and sieving to obtain a standby catalyst, the particle size of the standby catalyst being 25-300 μm;

[0012] (4) taking the iron-containing raw material, SiO2 powder, Al2O3 powder, and optionally, corresponding metal salts of one or more of K, Na, Ca, Mg, Mn and Ce, and then adding the standby catalyst, mixing and tabletting;

[0013] (5) repeating step (2) to perform melting treatment, and after the melting is completed, cooling, crushing and grinding, and sieving the granules with a particle size in the range of 15-300 μm, to obtain the Fischer-Tropsch synthesis fused iron catalyst.

[0014] In one embodiment, the addition amount of the standby catalyst in the mixture tablet obtained in step (4) is not more than 70 wt%, preferably 5-50 wt%, further preferably 10-45 wt%, such as 10 wt%, 15 wt%, 20 wt%, 30 wt%, 40 wt%, 45 wt%.

[0015] In one embodiment, the BET specific surface area of the Fischer-Tropsch synthesis fused iron catalyst is less than 50 m 2 / g, such as 45 m 2 / g, 40 m 2 / g, 35 m 2 / g, 30 m 2 / g, 25 m 2 / g, 20 m 2 / g, 15 m 2 / g or 10 m 2 / g, preferably less than 30 m 2 / g; the pore volume of the Fischer-Tropsch synthesis molten iron catalyst is lower than 45 cm 3 / g, such as 40 m 2 / g, 35 m 2 / g, 30 m 2 / g, 25 m 2 / g, 20 m 2 / g, 15 m 2 / g, or 10 m 2 / g, preferably lower than 25 cm 3 / g. In this context, the BET specific surface area refers to the BET specific surface area before reduction of the catalyst; the pore volume refers to the pore volume before reduction of the catalyst.

[0016] To further facilitate the effect of the catalyst, in an embodiment, the particle size of the Fischer-Tropsch synthesis molten iron catalyst ranges from 25 μm to 150 μm, such as 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, or 140 μm; and the particle size of the standby catalyst ranges from 25 μm to 150 μm, such as 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, or 140 μm.

[0017] In an embodiment, in the Fischer-Tropsch synthesis molten iron catalyst, the mass percentage of Fe element is 50% to 75%, such as 55%, 60%, 65%, or 70%; and the SiO2content is 0.1 to 20 g / 100 g Fe, such as 1, 3, 5, 7, 10, or 15 g / 100 g Fe; the Al2O3content is 0.1 to 20 g / 100 g Fe, such as 1, 3, 5, 7, 10, 15 g / 100 g Fe; the K2O content is 0 to 5 g / 100 g Fe, such as 0.1, 1, 1.5, 2, 2.5, 3, 4, 4.5 g / 100 g Fe; the Na2O content is 0 to 3 g / 100 g Fe, such as 0.1, 1, 1.5, 2, 2.5 g / 100 g Fe; the CaO content is 0 to 5 g / 100 g Fe, such as 0.1, 1, 2, 3, 4.5 g / 100 g Fe; the MgO content is 0 to 5 g / 100 g Fe, such as 0.1, 1, 2, 3, 4.5 g / 100 g Fe; the MnO content is 0 to 5 g / 100 g Fe, such as 0.1, 1, 2, 3, 4.5 g / 100 g Fe; the CeO2content is 0 to 5 g / 100 g Fe, such as 0.1, 1, 2, 3, 4.5 g / 100 g Fe. When the mass ratio is 0, it means that the component is not present.

[0018] In the present application, preferably, the SiO2content is 0.1-15 g / 100 g Fe; the Al2O3content is 0.1-15 g / 100 g Fe; in one embodiment, preferably, the K2O content is 0.1-3.5 g / 100 g Fe; the Na2O content is 0.1-2.5 g / 100 g Fe; the CaO content is 0.1-3.5 g / 100 g Fe; the MgO content is 0.1-3.5 g / 100 g Fe; the MnO content is 0-3 g / 100 g Fe; and the CeO2content is 0.1-5 g / 100 g Fe, based on the Fe element in the Fischer-Tropsch synthesis molten iron catalyst.

[0019] In one embodiment, the iron-containing raw material comprises one or more of magnetite, hematite and reduced iron powder, such as 0.5-5:1 magnetite and hematite, or 0.5-5:1 magnetite powder and reduced iron powder; in the Fischer-Tropsch synthesis molten iron catalyst of the present application, the Fe 3+ / Fe 2+ may be in the range of 0.5-5:1, such as 1:1, 2:1, 3:1, 4:1, 5:1, preferably 1-4:1.

[0020] In one embodiment, the residual screening material in step (5) is mixed into the iron-containing raw material in step (1) or step (4) for recycling.

[0021] In one embodiment, the source of Al2O3and SiO2may be one or more of the corresponding commercially available Al2O3and SiO2, or the corresponding minerals. The corresponding metal salt of one or more of K, Na, Ca, Mg, Mn and Ce can be a carbonate, nitrate, acetate, silicate, sulfate, etc., which is not particularly limited as long as it is a metal salt that can achieve the purpose of the present application.

[0022] In one embodiment, a step (3') is further included between steps (3) and (4), which is to determine the content of each component in the standby catalyst, and adjust the amount of the iron-containing raw material, SiO2powder, Al2O3powder, and the corresponding metal salt of one or more of K, Na, Ca, Mg, Mn and Ce in step (4) according to the difference between the preset component content of the Fischer-Tropsch synthesis molten iron catalyst and the above difference, so as to reduce the above difference. For example, when the molar ratio of Fe 3+ / Fe 2+ is not in the preset range of Fe 3+ / Fe 2+ , for example, not in the range of 0.5-5, the ratio of magnetite, hematite and reduced iron powder is adjusted to make the molar ratio of Fe 3+ / Fe 2+The ratio of the amount of substance of Fe element to the amount of substance of SiO2 is adjusted to be close to the preset range; when the mass of Fe element is lower than the preset value of the mass of Fe element, the mass of Fe element is adjusted to be close to the preset value by adding iron-containing raw materials; when the content of SiO2 is lower than the preset value of the content of SiO2, the content of SiO2 is adjusted to be close to the preset value by adding SiO2 powder or corresponding minerals; and when the content of Al2O3 is lower than the preset value of the content of Al2O3, the content of Al2O3 is adjusted to be close to the preset value by adding Al2O3 powder or corresponding minerals. Optionally, the contents of K2O, Na2O, CaO, MgO, MnO, CeO2 and the like in the Fischer-Tropsch synthesis molten iron catalyst can be adjusted in a similar manner. By supplementing iron-containing raw materials, SiO2 powder, Al2O3 powder and various metal salts during the smelting process, it is beneficial to make the content of each component in the obtained Fischer-Tropsch synthesis molten iron catalyst close to the preset value.

[0023] In an embodiment, the Fischer-Tropsch synthesis molten iron catalyst described in the application is activated in H2 with a space velocity of 100-1000 ml / (g·h), an activation temperature of 400-450°C, an activation time of 4-6h, and a pressure of 1-2.0MPa; the activated Fischer-Tropsch synthesis molten iron catalyst is used for high-temperature Fischer-Tropsch synthesis reaction, and the synthesis gas has H2 / CO=2-6; the reaction temperature is 300-350°C, and the reaction pressure is 2.0-2.5MPa.

[0024] Compared with the prior art, the application has the following characteristics:

[0025] A、The Fischer-Tropsch synthesis molten iron catalyst of the application has high mechanical strength and is suitable for use in a high-temperature fluidized bed reactor;

[0026] B、The Fischer-Tropsch synthesis molten iron catalyst of the application has a grading process in the preparation process, and the subsequent impregnation process does not greatly affect the particle size distribution of the catalyst, so the particle size distribution is concentrated, mainly concentrated in 25μm-150μm;

[0027] C、The application fully considers the influence of the melting process on the content of the promoter, and the promoter can be supplemented as appropriate during the catalyst preparation process, so that the content of the promoter in the finished catalyst is stable, and therefore the catalyst performance is stable, and the performance reproducibility of different batches of catalysts is good;

[0028] D、The catalyst prepared by the application has a simple preparation process, and basically no unqualified products are produced, so the catalyst production cost is low, and the catalyst is easy to be applied on a large scale;

[0029] E. For the Fischer-Tropsch synthesis molten iron catalyst prepared in this invention, the spare catalyst has a certain particle size distribution, and the single catalyst particles are formed after melting and cooling, have a certain strength and can withstand a certain temperature. Under certain melting conditions, they are not completely melted, and the spare catalyst itself has good catalytic activity. Therefore, during the melting process with other raw materials, some "defect sites" are generated around the spare catalyst that is not completely melted. These "defect sites" become new active centers, improving the catalyst activity.

[0030] F. The Fischer-Tropsch synthesis molten iron catalyst prepared by this invention exhibits excellent catalytic performance, meeting the following criteria: CO conversion rate higher than 90%, CH4 selectivity lower than 10%, the sum of CH4 and CO2 selectivity lower than 20%, and the sum of C2 to C4 olefin selectivity higher than 25%. The overall technical performance of the Fischer-Tropsch synthesis molten iron catalyst prepared by this invention is superior to that of existing catalysts. Detailed Implementation

[0031] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0032] Example 1

[0033] Preparation of Material 1: Weigh out 75g of magnetite powder; 25.85g of hematite powder; 1.75g ​​of Al2O3; 1.75g ​​of SiO2; 1.82g of K2CO3; 1.90g of CaCO3; 1.0g of MgCO3; 11.2g of Ce(NO3)3·9H2O; 1.3g of Mn(NO3)2; and 2.25g of NaNO3.

[0034] Preparation of the backup catalyst: Material 1 was thoroughly mixed in a mixer and then tableted in a tablet press. It was then transferred to a vacuum melting furnace, evacuated to 5 Pa (gauge pressure), and then purged with argon gas to -0.05 MPa (absolute pressure). This process was repeated three times. Melting was then carried out at 1200℃ for 30 minutes. After melting, 15℃ cooling water was circulated through the jacket around the material tray to rapidly cool the material. After cooling, the connecting valve was opened, and the material was removed from the melting furnace after the furnace pressure returned to normal. It was first coarsely crushed in a crusher, then finely ground in a mortar, and finally sieved on an automatic sieve to obtain backup catalyst 1 with a particle size distribution of 25–150 μm, denoted as Backup 1.

[0035] Preparation of material 2: Weighed magnetite powder: 50 g; hematite powder: 17.23 g; Al2O3: 1.17 g; SiO2: 1.17 g; K2CO3: 1.46 g; CaCO3: 1.23 g; MgCO3: 0.73 g; Ce(NO3)3·9H2O: 7.47 g; NaNO3: 1.80 g; Mn(NO3)2: 1.0 g; standby catalyst 1: 50 g.

[0036] Preparation of molten iron catalyst: After the material 2 was mixed evenly in the mixer, it was tabletted in the tablet machine, and then was smelted, cooled, crushed, and sieved in the same way as the above-mentioned "preparation of standby catalyst 1", and the catalyst with a particle size range of 25-150 μm was taken as the Fischer-Tropsch synthesis molten iron catalyst 1, recorded as cat 1.

[0037] Example 2

[0038] The Fischer-Tropsch synthesis molten iron catalyst 2 was prepared in the same way as in Example 1, and the only difference from Example 1 was that the preparation of material 2 in Example 1 was adjusted as follows: weighed magnetite powder: 60 g; hematite powder: 20.68 g; Al2O3: 1.40 g; SiO2: 1.40 g; K2CO3: 1.61 g; CaCO3: 1.48 g; MgCO3: 0.80 g; Ce(NO3)3·9H2O: 8.96 g; NaNO3: 1.98 g; Mn(NO3)2: 0.91 g; standby catalyst 1: 25 g.

[0039] The Fischer-Tropsch synthesis molten iron catalyst 2 (with a particle size distribution of 25-150 μm) was obtained, recorded as cat 2.

[0040] Example 3

[0041] Preparation of material 1: weighed magnetite powder: 100 g; Al2O3: 1.75 g; SiO2: 1.75 g; K2CO3: 1.82 g; CaCO3: 1.90 g; MgCO3: 1.0 g; Ce(NO3)3·9H2O: 11.2 g; NaNO3: 2.25 g; Mn(NO3)2: 1.3 g.

[0042] Preparation of standby catalyst: the material 1 of this example was treated in the same way as the "preparation of standby catalyst" step in Example 1, and standby catalyst 3 was obtained, recorded as standby 3.

[0043] Preparation of material 2: Weigh magnetite powder: 75 g; Al2O3: 1.17 g; SiO2: 1.17 g; K2CO3: 1.46 g; CaCO3: 1.23 g; MgCO3: 0.73 g; Ce(NO3)3-9H2O: 7.47 g; NaNO3: 1.80 g; Mn(NO3)2: 1.0 g; standby catalyst 3: 50 g.

[0044] Preparation of molten iron catalyst: material 2 of this example was treated in the same way as the "preparation of molten iron catalyst" step in Example 1 to obtain a Fischer-Tropsch synthesis molten iron catalyst 3 (particle size distribution of 25-150 μm), denoted as catalyst 3.

[0045] Example 4

[0046] Preparation of material 1: Weigh magnetite powder: 90.2 g; reduced iron powder: 5.3 g; Al2O3: 1.75 g; SiO2: 1.75 g; K2CO3: 1.82 g; CaCO3: 1.90 g; MgCO3: 1.0 g; Ce(NO3)3-9H2O: 11.2 g; NaNO3: 2.25 g; Mn(NO3)2: 1.3 g.

[0047] Preparation of standby catalyst: material 1 of this example was treated in the same way as the "preparation of standby catalyst" step in Example 1 to obtain a standby catalyst 4, denoted as standby 4.

[0048] Preparation of material 2: Weigh magnetite powder: 67.5 g; reduced iron powder: 4.0 g; Al2O3: 1.17 g; SiO2: 1.17 g; K2CO3: 1.46 g; CaCO3: 1.23 g; MgCO3: 0.73 g; Ce(NO3)3-9H2O: 7.47 g; NaNO3: 1.80 g; Mn(NO3)2: 1.0 g; standby catalyst 4: 50 g.

[0049] Preparation of molten iron catalyst: material 2 of this example was treated in the same way as the "preparation of molten iron catalyst" step in Example 1 to obtain a molten iron catalyst 4 (particle size distribution of 25-150 μm), denoted as catalyst 4.

[0050] Example 5

[0051] Preparation of material 1: Weigh magnetite powder: 75 g; hematite powder: 25.85 g; SiO2: 3.50 g; K2CO3: 2.73 g; CaCO3: 1.0 g; MgCO3: 1.9 g; Ce(NO3)3-9H2O: 5.6 g; Mn(NO3)2: 2.6 g; NaNO3: 1.15 g.

[0052] Preparation of standby catalyst: The material 1 of this example was treated in the same way as the "Preparation of standby catalyst" step in Example 1 to obtain standby catalyst 5, denoted as standby 5.

[0053] Preparation of material 2: Weighed magnetite powder: 50 g; hematite powder: 17.23 g; SiO2: 2.34 g; K2CO3: 2.18 g; CaCO3: 0.73 g; MgCO3: 1.23 g; Ce(NO3)3-9H2O: 3.74 g; NaNO3: 0.90 g; Mn(NO3)2: 2.0 g; standby catalyst 5: 50 g.

[0054] Preparation of molten iron catalyst: The material 2 of this example was treated in the same way as the "Preparation of molten iron catalyst" step in Example 1 to obtain Fischer-Tropsch synthesis molten iron catalyst 5 (particle size distribution of 25-150 μm), denoted as catalyst 5.

[0055] Example 6

[0056] Preparation of material 1: Weighed magnetite powder: 75 g; hematite powder: 25.85 g; Al2O3: 3.50 g; K2CO3: 0.91 g; CaCO3: 2.0 g; MgCO3: 3.8 g; Ce(NO3)3-9H2O: 8.4 g; Mn(NO3)2: 1.3 g; NaNO3: 3.45 g.

[0057] Preparation of standby catalyst: The material 1 of this example was treated in the same way as the "Preparation of standby catalyst" step in Example 1 to obtain standby catalyst 6, denoted as standby 6.

[0058] Preparation of material 2: Weighed magnetite powder: 50 g; hematite powder: 17.23 g; Al2O3: 2.34 g; K2CO3: 0.73 g; CaCO3: 1.50 g; MgCO3: 2.88 g; Ce(NO3)3-9H2O: 6.3 g; Mn(NO3)2: 0.93 g; NaNO3: 2.59 g; standby catalyst 6: 50 g.

[0059] Preparation of molten iron catalyst: The material 2 of this example was treated in the same way as the "Preparation of molten iron catalyst" step in Example 1 to obtain Fischer-Tropsch synthesis molten iron catalyst 6 (particle size distribution of 25-150 μm), denoted as catalyst 6.

[0060] Example 7

[0061] Preparation of material 1 : Weighed magnetite powder: 75 g; hematite powder: 25.85 g; Al2O3: 3.50 g; SiO2: 3.50 g; K2CO3: 3.64 g; CaCO3: 3.80 g; MgCO3: 2.0 g; Ce(NO3)3-9H2O: 11.2 g; Mn(NO3)2: 2.6 g; NaNO3: 4.50 g.

[0062] Preparation of standby catalyst: The material 1 of this example was treated in the same way as the "Preparation of standby catalyst" step in Example 1 to obtain standby catalyst 7, denoted as standby 7.

[0063] Preparation of material 2: Weighed magnetite powder: 50 g; hematite powder: 17.23 g; Al2O3: 2.34 g; SiO2: 2.34 g; K2CO3: 2.73 g; CaCO3: 2.78 g; MgCO3: 1.50 g; Ce(NO3)3-9H2O: 7.47 g; NaNO3: 1.80 g; Mn(NO3)2: 3.90 g; standby catalyst 7: 50 g.

[0064] Preparation of molten iron catalyst: The material 2 of this example was treated in the same way as the "Preparation of molten iron catalyst" step in Example 1 to obtain a Fischer-Tropsch synthesis molten iron catalyst 7 (particle size distribution of 25-150 μm), denoted as catalyst 7.

[0065] Comparative Example 1

[0066] Material 1 : Weighed magnetite powder: 75 g; hematite powder: 25.85 g; Al2O3: 1.75 g; SiO2: 1.75 g; K2CO3: 1.82 g; CaCO3: 1.90 g; MgCO3: 1.0 g; Ce(NO3)3-9H2O: 11.2 g; Mn(NO3)2: 1.3 g; NaNO3: 2.25 g (same material ratio as Example 1).

[0067] The material 1 was treated in the same way as the "Preparation of standby catalyst" step in Example 1, and then the prepared material was crushed to below 25 μm as a standby catalyst. Then, the catalyst was prepared in the same way as the "Preparation of molten iron catalyst" step in Example 1, with the difference that only the prepared standby catalyst was used as the material 2. The catalyst having a particle size range of 25-150 μm was taken to obtain a comparative catalyst 1, denoted as comparative 1.

[0068] Comparative Example 2

[0069] The standby catalyst of Comparative Example 2 was prepared in the same manner as the "Preparation of standby catalyst" procedure of Example 3, except that the particle size range of the standby catalyst was below 25 μm.

[0070] Preparation of material 2: The magnetite powder was weighed again: 66.67 g; Al2O3: 1.17 g; SiO2: 1.17 g; K2CO3: 1.46 g; CaCO3: 1.23 g; MgCO3: 0.73 g; Ce(NO3)3-9H2O: 7.47 g; NaNO3: 1.80 g; Mn(NO3)2: 1.0 g; and 50 g of the standby catalyst was added again.

[0071] The material 2 of the present comparative example was treated in the same manner as the "Preparation of molten iron catalyst" procedure of Example 3 to obtain the comparative catalyst 2 (particle size distribution of 25-150 μm), which was denoted as Comp. 2.

[0072] Comparative Example 3

[0073] The standby catalyst of Comparative Example 3 was prepared in the same manner as the "Preparation of standby catalyst" procedure of Example 4, except that the particle size range of the standby catalyst was below 25 μm.

[0074] Preparation of material 2: The magnetite powder was weighed again: 66.67 g; Al2O3: 1.17 g; SiO2: 1.17 g; K2CO3: 1.46 g; CaCO3: 1.23 g; MgCO3: 0.73 g; Ce(NO3)3-9H2O: 7.47 g; NaNO3: 1.80 g; Mn(NO3)2: 1.0 g; and 50 g of the standby catalyst was added again.

[0075] The material 2 of the present comparative example was treated in the same manner as the "Preparation of molten iron catalyst" procedure of Example 4 to obtain the comparative catalyst 3 (particle size distribution of 25-150 μm), which was denoted as Comp. 3.

[0076] Analysis of component content and structure parameters

[0077] The content of each substance in the above molten iron catalyst and standby catalyst was analyzed. The content of iron element in the molten iron catalyst was measured by X-ray fluorescence spectrometry, the molar ratio of Fe 3+ / Fe 2+ was measured by coordination titration and redox titration, the content of SiO2, Al2O3, K2O, Na2O, CaO, MgO, MnO and CeO2 was measured by X-ray fluorescence spectrometry, and the results are shown in Table 1. The structure parameters of catalyst standby 1 and catalyst 1 were analyzed, and the specific surface area and pore volume of the finished catalyst carrier were measured by multipoint BET test method, and the results are shown in Table 2.

[0078] Table 1: Contents of each component in the melt iron catalyst and the standby catalyst in Examples 1-7 and Comparative Examples 1-3

[0079]

[0080]

[0081] Note: In Table 1, the contents of SiO2, Al2O3, K2O, Na2O, CaO, MgO, MnO and CeO2 are relative to the content of 100 g of iron.

[0082] As shown in Table 1, by comparing the standby catalyst and the melt iron catalyst, it can be seen that the content of the auxiliary agent in the Fischer-Tropsch synthesis melt iron catalyst of the present application is appropriately floating, and through this method, the raw material can be supplemented to adjust the element content of the catalyst according to the situation, thereby being conducive to stabilizing the performance of the product catalyst between batches.

[0083] Table 2: Structural parameters of the melt iron catalyst and the standby catalyst in Examples 1-7 and Comparative Examples 1-3

[0084]

[0085]

[0086] As can be seen from Table 2, after adding the standby catalyst with a particle size distribution in the range of 25-150 μm, the specific surface area and pore volume of the melt iron catalyst have been improved to a certain extent. By comparing Cat 3 and Comp 2, and Cat 4 and Comp 3, it can be seen that after adding the standby catalyst with a particle size of less than 25 μm, the specific surface area and pore volume of the melt iron catalyst do not change significantly.

[0087] Evaluation of catalyst performance

[0088] The melt iron catalyst and the standby catalyst of Examples 1-7 and Comparative Examples 1-3 were evaluated for performance using a fluidized bed reactor (evaluation conditions: pressure, 2.2 MPa; H2 / CO, 4; CO / CO2, 1.5; gas space velocity: 20000 ml / (g·h), temperature: 320°C). The gas flow was controlled by a Brooks flowmeter, and the reaction products successively passed through a hot trap, a cold trap, and then the non-condensed components entered the exhaust system and were analyzed by gas chromatography in time online. The cold trap products were mixed with the hot trap products after oil-water separation, and were analyzed by gas chromatography offline. Through the analysis results, the performance indicators of the catalyst were calculated. The results are shown in Table 3.

[0089] Table 3: Performance test indicators of the melt iron catalyst in Examples 1-7 and Comparative Examples 1-3

[0090]

[0091]

Claims

1. A method for preparing a Fischer-Tropsch synthesis molten iron catalyst, characterized in that, The preparation method includes the following steps: (1) The iron-containing raw material is mixed with SiO2 powder and Al2O3 powder, and optionally with one or more corresponding metal salts of K, Na, Ca, Mg, Mn and Ce, and then compressed into tablets. (2) The obtained mixture is compressed into tablets and transferred to a melting furnace for vacuum extraction and argon replacement treatment. Then, it is melted at 1800-2200℃ to obtain a melted product. The melting time is 5-15 min. (3) After the molten product cools down, it is crushed, ground and sieved to obtain a spare catalyst with a particle size of 25μm to 300μm. (4) Take the iron-containing raw material, SiO2 powder, Al2O3 powder, and optionally one or more of the corresponding metal salts of K, Na, Ca, Mg, Mn and Ce, add the prepared catalyst, mix well and compress into tablets; (5) Repeat step (2) for melting treatment. After melting, cool, crush and grind, and then screen out the granules with a particle size in the range of 15μm to 300μm, which are the Fischer-Tropsch synthesis molten iron catalysts. The Fischer-Tropsch molten iron catalyst contains 50%–75% Fe by mass; and based on the Fe content in the Fischer-Tropsch molten iron catalyst, the content of SiO2 is 0.1–20 g / 100 g Fe; the content of Al2O3 is 0.1–20 g / 100 g Fe; the content of K2O is 0–5 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; the content of CeO2 is 0–5 g / 100 g Fe; and the content of Fe is 0. 3+ / Fe 2+ The ratio of the amounts of substance ranges from 0.5 to 5:

1.

2. The preparation method according to claim 1, characterized in that, In step (4), the amount of the spare catalyst added in the tablet of the mixture obtained in step (4) does not exceed 70 wt%.

3. The preparation method according to claim 2, characterized in that, In step (4), the amount of the spare catalyst added is 5 to 50 wt% in the tablet of the mixture obtained in step (4).

4. The preparation method according to claim 3, characterized in that, In step (4), the amount of the spare catalyst added is 10-45 wt% in the tablet of the mixture obtained in step (4).

5. The preparation method according to claim 1, characterized in that, The BET specific surface area of ​​the Fischer-Tropsch synthesis molten iron catalyst is less than 50 m². 2 / g; the pore volume of the Fischer-Tropsch molten iron catalyst is less than 45 cm³. 3 / g.

6. The preparation method according to claim 4, characterized in that, The BET specific surface area of ​​the Fischer-Tropsch synthesis molten iron catalyst is less than 30 m². 2 / g; the pore volume of the Fischer-Tropsch molten iron catalyst is less than 25 cm³. 3 / g.

7. The preparation method according to claim 1, characterized in that, The particle size range of the Fischer-Tropsch synthesis molten iron catalyst is 25 μm to 150 μm; the particle size range of the standby catalyst is 25 μm to 150 μm.

8. The preparation method according to claim 6, characterized in that, The particle size range of the Fischer-Tropsch synthesis molten iron catalyst is 25 μm to 150 μm; the particle size range of the standby catalyst is 25 μm to 150 μm.

9. The preparation method according to any one of claims 1 to 8, characterized in that, In the Fischer-Tropsch synthesis molten iron catalyst, based on the Fe element content, the content of SiO2 is 0.1–15 g / 100 g Fe; the content of Al2O3 is 0.1–15 g / 100 g Fe; the content of K2O is 0.1–3.5 g / 100 g Fe; the content of Na2O is 0.1–2.5 g / 100 g Fe; the content of CaO is 0.1–3.5 g / 100 g Fe; the content of MgO is 0.1–3.5 g / 100 g Fe; the content of MnO is 0–3 g / 100 g Fe; and the content of CeO2 is 0.1–5 g / 100 g Fe.

10. The preparation method according to claim 9, characterized in that, The iron-containing raw materials include one or more of magnetite, hematite, and reduced iron powder.

11. The preparation method according to any one of claims 1 to 8 and 10, characterized in that, The remaining screened material in step (5) is recycled as the iron-containing raw material in step (1) or step (4).

12. The preparation method according to any one of claims 1 to 8 and 10, characterized in that, Fe 3+ / Fe 2+ The ratio of the amounts of substance ranges from 1 to 4:

1.

13. The preparation method according to any one of claims 1 to 8 and 10, characterized in that, The metal salt is one or more of carbonates, nitrates, acetates, silicates, and sulfates.

14. A method of using a Fischer-Tropsch synthesis molten iron catalyst, characterized in that, The Fischer-Tropsch synthesis molten iron catalyst is prepared by the method described in any one of claims 1 to 13; when used... The Fischer-Tropsch synthesis molten iron catalyst was activated in H2 at a space velocity of 100–1000 ml / (g·h) at an activation temperature of 400–450 °C for 4–6 h at a pressure of 1–2.0 MPa. The activated Fischer-Tropsch synthesis molten iron catalyst was used in a high-temperature Fischer-Tropsch synthesis reaction, with an H2 / CO ratio of 2 to 6 in the synthesis gas; a reaction temperature of 300 to 350°C; and a reaction pressure of 2.0 to 2.5 MPa.

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