A modified Fischer-Tropsch iron-based catalyst

Abstract

This invention provides a modified Fischer-Tropsch iron-based catalyst comprising a SiO2 support modified with a ternary modifier. The ternary modifier is composed of any one of Mg and Ca, along with Zr and B elements, and the total mass of the ternary modifier is 10-60% of the SiO2 support. The modified Fischer-Tropsch iron-based catalyst provided by this invention utilizes a ternary modifier to modify the silicon source. After preparation, the catalyst exhibits improved reaction stability and anti-wear properties. Furthermore, it effectively inhibits the loss of the promoter K during Fischer-Tropsch synthesis and further enhances the catalyst's activity, selectivity, and reaction stability. The modified Fischer-Tropsch iron-based catalyst provided by this invention exhibits excellent performance, is simple to prepare, is suitable for large-scale production, and possesses significant economic and social value, thus demonstrating great application potential.

Description

Technical Field

[0001] This invention relates to the field of catalysts, and more specifically to a modified Fischer-Tropsch iron-based catalyst. Background Technology

[0002] Fischer-Tropsch synthesis was first discovered in the 1920s by German chemists Fischer and Tropsch. It is an important pathway for converting coal and natural gas into liquid fuels or high-value-added chemical products. In the 1950s, Sasol in South Africa achieved industrial-scale production of Fischer-Tropsch synthesis, using Fischer-Tropsch iron-based catalysts. The reactors used in Fischer-Tropsch synthesis mainly include fixed-bed reactors, fluidized-bed reactors, and slurry-bed reactors. Slurry-bed reactors have significant technological advantages due to their low investment cost, high production efficiency, easy catalyst loading and unloading, good heat exchange conditions in the reaction system, and the ability to directly use coal-based syngas with a low H2 / CO ratio. The iron-based catalyst used in slurry-bed reactors needs to have certain reactivity and excellent chemical stability, and the catalyst particles also need to have suitable particle size and wear resistance to ensure reaction efficiency and online separation of the Fischer-Tropsch product wax from the catalyst.

[0003] Patent CN 104785276B provides a Fischer-Tropsch synthesis catalyst prepared using a composite sol as a silicon source, its preparation method and application. The preparation process of the composite sol requires sequential chemical treatment of silicon raw materials, mixing of modifiers and aging process, which is complex and costly.

[0004] Patent CN 109225235B discloses a highly efficient and wear-resistant slurry-bed Fischer-Tropsch synthesis iron-based catalyst, its preparation method, and its application. The key technical point of this invention is that nano-inorganic non-metallic particles such as diatomaceous earth, montmorillonite, or activated clay are mixed with silica sol as modifiers, and the modified slurry is further used for catalyst preparation. While this preparation method improves the catalyst's wear resistance, achieving uniform dispersion of the high-density solid particles within the sol system during preparation is challenging. Furthermore, the catalyst prepared by this method has a relatively low pore volume, which is detrimental to the mass transfer and diffusion of long-chain product molecules.

[0005] In conclusion, there is an urgent need to design a Fischer-Tropsch iron-based catalyst that is easy to process, stable, and has excellent wear resistance, which has significant industrial and social implications. Summary of the Invention

[0006] To overcome the shortcomings of the existing technology, one object of the present invention is to provide a modified Fischer-Tropsch iron-based catalyst, which modifies the silicon source by using a ternary modifier, thereby changing the microstructure of the catalyst and significantly improving a number of catalyst properties.

[0007] The modified Fischer-Tropsch iron-based catalyst provided by the present invention comprises a SiO2 support, wherein the SiO2 support is modified with a ternary modifier, the ternary modifier being composed of any one of Mg and Ca, and Zr and B elements, and the total mass of the ternary modifier being 10-60% of the SiO2 support by mass percentage.

[0008] The modified Fischer-Tropsch iron-based catalyst provided by this invention uses a novel ternary modifier to in-situ modify a silicon source, and further prepares the Fischer-Tropsch iron-based catalyst using the modified silicon source, which forms a modified SiO2 support. Figure 1 As shown, the active components in the catalyst prepared using the modified silicon source did not exhibit significant crystallization, while the active components in the catalyst prepared using the unmodified silicon source showed a certain degree of crystallization, even though the catalyst contained the same elemental composition. This indicates that the silicon source modified with the ternary modifier can form a more robust three-dimensional network in the catalyst, thus better confining the active phase and increasing the catalyst's wear resistance, thereby hindering the sintering deactivation of the active phase and the breakage of the catalyst bulk phase.

[0009] In addition, the modified catalyst provided by this invention can enhance the interaction between the active phase and the K element in the Fischer-Tropsch synthesis process through the synergistic effect of the ternary modifier, thereby effectively inhibiting the loss of K promoter and thus improving the catalyst's activity, selectivity and reaction stability.

[0010] In some embodiments of the modified Fischer-Tropsch iron-based catalyst according to the present invention, the total mass of the ternary modifier can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% of the SiO2 support, or any combination thereof. In some preferred embodiments, the total mass of the ternary modifier can be 10-40% of the SiO2 support.

[0011] In some embodiments of the modified Fischer-Tropsch iron-based catalyst according to the present invention, the mass ratio of any one of Mg and Ca, Zr, and B in the ternary modifier can be 0.1–5:0.1–5:1. In some preferred embodiments, the mass ratio of any one of Mg and Ca, Zr, and B can be 0.5–2:0.5–2:1. In some more preferred embodiments, the mass ratio of any one of Mg and Ca, Zr, and B can be 0.5–1.5:0.5–1.5:1, for example, the mass ratio of any one of Mg and Ca, Zr, and B can be 0.8–1.2:0.8–1.2:1.

[0012] In this invention, the modification of the SiO2 support is achieved by modifying the silicon source. The silicon source refers to the source material of the SiO2 support during the preparation of Fischer-Tropsch iron-based catalysts. By using a ternary modifier to modify a conventional silicon source, the resulting modified silicon source can directly participate in the preparation process of Fischer-Tropsch iron-based catalysts without significantly altering the original process. The process is simple, the conditions are mild, and it has strong applicability.

[0013] In some embodiments of the modified Fischer-Tropsch iron-based catalyst according to the present invention, the modification of the silicon source may include the following steps:

[0014] S1': A ternary modifier aqueous solution is prepared by combining a water-soluble salt of Mg or Ca, a water-soluble salt of Zr, and boric acid, and an unmodified initial silicon source solution is prepared; and

[0015] S2': The modified silicon source solution is prepared by co-precipitation reaction of the ternary modifier aqueous solution and the initial silicon source solution.

[0016] Compared to the conventional unidirectional precipitation process, using co-precipitation when modifying silicon source solution with ternary modifiers allows for more consistent control of process conditions, resulting in products with better structural uniformity and less particle agglomeration.

[0017] In some embodiments of the modified Fischer-Tropsch iron-based catalyst according to the present invention, the preparation of the catalyst may include the following steps:

[0018] S1: Prepare a ternary modifier aqueous solution by using water-soluble salts of Mg or Ca, water-soluble salts of Zr, and boric acid, and prepare an unmodified initial silicon source solution;

[0019] S2: The modified silicon source solution is prepared by co-precipitation reaction of the ternary modifier aqueous solution and the initial silicon source solution; and

[0020] S3: The modified Fischer-Tropsch iron-based catalyst is prepared using the modified silicon source solution.

[0021] In some preferred embodiments, the total concentration of any one of the elements Mg and Ca, Zr and B in the ternary modifier aqueous solution, by mass percentage, can be 0.2% to 5%, for example, 0.2%, 0.5%, 1.0%, 1.5%, 1.8%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, or any combination of concentration ranges.

[0022] In some preferred embodiments, the water-soluble salt can be a nitrate, that is, the raw material of the ternary modifier can be magnesium nitrate and its hydrate (e.g., Mg(NO3)2·6H2O), calcium nitrate and its hydrate (e.g., Ca(NO3)2·4H2O), zirconium nitrate and its hydrate (e.g., Zr(NO3)4·5H2O).

[0023] In some preferred embodiments, the initial silicon source solution may be an aqueous solution of potassium silicate, sodium silicate sol, or ammonia silicate sol, wherein the SiO2 concentration, by mass percentage, may be 0.5% to 35%, preferably 1% to 10%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 15%, 20%, 25%, 30%, 35%, or any combination of concentration ranges.

[0024] In some preferred embodiments, the reaction temperature of the co-current coprecipitation reaction can be 5–90°C, for example, 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or any combination of these temperature ranges. In other preferred embodiments, the precipitation time of the co-current coprecipitation reaction can be 0.5–5 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or any combination of these time ranges. In still other preferred embodiments, during the co-current coprecipitation reaction, the pH value is controlled to be 4–12, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, or any combination of these pH value ranges.

[0025] In this invention, the modified SiO2 support is applicable to Fischer-Tropsch iron-based catalysts commonly used in the art. Besides using the modified silicon source, the preparation process of the Fischer-Tropsch iron-based catalyst can also be a common process in the art.

[0026] In some embodiments of the modified Fischer-Tropsch iron-based catalyst according to the present invention, the modified Fischer-Tropsch iron-based catalyst may contain the following components in a mass ratio: Fe2O3: metal X1 additive: K additive: X2: SiO2 support = 100:0.5~25:0.1~5:1~15:5~30, wherein X1 represents one or more of Ti, V, Cr, Mn, Cu, Zn, Al, and Nd, and X2 represents a ternary modifier. Those skilled in the art can adjust the type of X1 additive and the amount of each component according to actual applications. In some preferred embodiments, the mass ratio may be 100:1~15:1~5:2~10:10~25. In some more preferred embodiments, the mass ratio may be 100:2~10:1~5:2~10:12~22.

[0027] In some embodiments of the modified Fischer-Tropsch iron-based catalyst according to the present invention, its preparation may include the following steps:

[0028] T1: A mixed aqueous solution is formed by the water-soluble salt of Fe and the water-soluble salt containing metal X1, and then co-precipitated with a precipitant to separate the resulting precipitate;

[0029] T2: The precipitate is mixed with the precursor aqueous solution of K auxiliary agent and the modified silicon source solution modified by the ternary modifier and subjected to slurry treatment to obtain a catalyst precursor slurry; and

[0030] T3: The catalyst precursor slurry is dried, shaped, and calcined.

[0031] In some preferred embodiments, in step T1, the water-soluble salt of Fe can be a nitrate of Fe, i.e., ferric nitrate and its hydrate (e.g., Fe(NO3)3·9H2O); the water-soluble salt containing metal X1 can be a nitrate containing metal X1, i.e., nitric acid X1 and its hydrate (e.g., Cu(NO3)2·3H2O, Mn(NO3)2·4H2O, Nd(NO3)3·6H2O, Zn(NO3)2·6H2O, Ti(NO3)4, Al(NO3)3·9H2O, etc.), or the water-soluble salt containing metal X1 can be KVO3.

[0032] In some preferred embodiments, in step T1, the mixed aqueous solution and the precipitant undergo a co-precipitation reaction in a parallel flow. This precipitation method allows for more consistent control of process conditions, resulting in a more uniform product structure and less particle agglomeration. The reaction temperature can be 5–90°C, for example, 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or any combination thereof. The precipitation time is 0.5–5 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or any combination thereof. During the reaction, the pH value is controlled to be 4–12, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, or any combination thereof.

[0033] In some preferred embodiments, in step T1, the precipitant can be a common precipitant in the art, including but not limited to ammonia, sodium carbonate, ammonium carbonate, sodium hydroxide, etc., and more preferably ammonia.

[0034] In some preferred embodiments, in step T2, the modified silicon source solution modified by the ternary modifier can be modified according to the method described in the foregoing technical solution, such as steps S1' and S2', or other similar modification methods.

[0035] In some preferred embodiments, in step T2, the precursor of the K auxiliary agent can be a type commonly found in the art, including but not limited to one or more of potassium nitrate, potassium carbonate, and potassium bicarbonate, with potassium nitrate being preferred. The concentration of the aqueous solution of the K auxiliary agent precursor, by mass percentage, can be 5-15%, for example, 5%, 8%, 10%, 12%, 15%, or any combination thereof.

[0036] In some preferred embodiments, in step T2, the temperature of the pulping treatment can be 10–60°C, for example, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, or any combination of temperature ranges; the pulping time can be 0.5–5 h, for example, 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, or any combination of time ranges; and the mass percentage concentration of the pulp can be 5–35%, for example, 5–20%, 10–20%, or 10–15%.

[0037] In some preferred embodiments, in step T3, the drying and molding process can be spray drying, wherein the inlet air temperature can be 150–350°C, the outlet air temperature can be 90–205°C, and the drying time can be 5–20 hours. In some more preferred embodiments, the inlet air temperature can be 260–300°C, the outlet air temperature can be 90–120°C, and the drying time can be 10–15 hours.

[0038] In some preferred embodiments, in step T3, the calcination temperature can be 300–700°C, and the calcination time can be 3–12 hours. In some more preferred embodiments, the calcination temperature can be 500–650°C, and the calcination time can be 3–8 hours.

[0039] The modified Fischer-Tropsch iron-based catalyst provided by this invention has the following advantages:

[0040] (1) The silicon source is modified by a ternary modifier composed of Mg or Ca elements, Zr elements, and B elements. The modified silicon source can form a new and tougher three-dimensional spatial network when preparing Fischer-Tropsch iron-based catalysts. The specific surface area and pore volume of the catalyst are significantly increased, thereby significantly improving the performance of the catalyst. In the Fischer-Tropsch synthesis process, the anti-wear strength of the catalyst is increased, thereby improving the reaction stability and anti-wear properties of the catalyst.

[0041] (2) The ternary modifier can also enhance the interaction between the active phase of the catalyst and the K element of the promoter, thereby effectively inhibiting the loss of the promoter K and further improving the activity, selectivity and reaction stability of the catalyst.

[0042] (3) The catalyst provided by the present invention only requires modification of the silicon source. The preparation process is simple, flexible, and has good applicability, without high cost.

[0043] In summary, the modified Fischer-Tropsch iron-based catalyst provided by this invention has excellent performance, is easy to prepare, is suitable for large-scale production, and has significant economic and social value, thus showing great application potential. Attached Figure Description

[0044] Figure 1 XRD patterns of a Fischer-Tropsch iron-based catalyst prepared by modifying a silicon source with a ternary modifier (the catalyst prepared in Example 1, denoted as "1") and a Fischer-Tropsch iron-based catalyst prepared without modifying a silicon source with a ternary modifier (the catalyst prepared in Comparative Example 11, denoted as "2"). Detailed Implementation

[0045] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0046] The testing method used in this invention is as follows:

[0047] 1) Catalyst weight composition

[0048] X-ray fluorescence spectrometry (XRF) was used for determination. The model was ZSX Primus II (Rigaku), with an upside radiation X-ray generator, a 4kW Rh target, and the tested element category range was FU. The test area diameter was 30 mm, and the test method was a semi-quantitative method for all elements.

[0049] 2) K churn rate

[0050] This indicates the percentage loss of potassium (K) content in the catalyst compared to the K content in fresh catalyst after 1000 hours of continuous reaction.

[0051] Calculation formula: K loss rate (%) = % × (K content of fresh catalyst - K content of catalyst in 1000h) / K content of fresh catalyst

[0052] 3) Specific surface area and pore structure of the catalyst

[0053] The specific surface area was determined using a Micromeritics ASAP 2000 physical adsorption instrument. During the test, the sample was cooled to -196°C in liquid nitrogen to conduct a low-temperature N2 adsorption-desorption experiment. The specific surface area was then calculated using the BET equation, and the pore structure was calculated using the BJH method.

[0054] 4) Chemical wear value

[0055] The determination was performed in accordance with the published patent CN 112414995A (a method for determining catalyst wear rate).

[0056] 5) Inactivation rate

[0057] This represents the difference between the initial CO conversion rate and the CO conversion rate after 1000 hours of continuous reaction, under the condition that the reaction conditions remain unchanged, and then divided by the initial CO conversion rate.

[0058] The calculation formula is as follows: Inactivation rate (%) = % × (Initial CO conversion rate - 1000h CO conversion rate) / Initial CO conversion rate

[0059] 6) Catalyst performance evaluation

[0060] The reaction was carried out in a laboratory slurry bed reactor: the catalyst to be tested was reduced with syngas at a volume ratio of H2 / CO of 2:1 for 24 h at a pressure of 0.2 MPa, a space velocity of 2000 ml / g / h, and a temperature of 280 °C. The reaction was then continued at a temperature of 260–265 °C, a catalyst space velocity of 19000 ml / g / h, a pressure of 3.0 MPa, a feed gas H2 / CO ratio of 1.8–2.0, and a tail gas recycle ratio of 2.0.

[0061] The CO conversion rate is calculated as the number of moles of CO converted / the number of moles of imported CO; the CO2 selectivity is calculated as the number of moles of CO2 generated / the number of moles of CO converted; and the hydrocarbon selectivity in the product is determined as the number of moles of CO consumed to generate the hydrocarbon product / the number of moles of CO consumed to generate the total hydrocarbons.

[0062] Unless otherwise specified, all raw materials or reagents used in the embodiments and comparative examples of this invention are commercially available products.

[0063] Unless otherwise specified, all percentages used in the embodiments and comparative examples of this invention are mass percentages.

[0064] Example 1

[0065] 417.0 g Mg(NO3)2·6H2O, 186.0 g Zr(NO3)4·5H2O, and 226.1 g H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-current co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 7.5, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0066] 10 kg of Fe(NO3)3·9H2O and 190 g of Cu(NO3)2·3H2O were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron-copper mixed solution was then precipitated in parallel with the ammonia solution at a precipitation temperature of 50 °C for 1 h, with the pH controlled at 7.0. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 155 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.5%, the slurrying temperature was 30 °C, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0067] Spray drying was performed with the inlet temperature controlled at 290℃ and the outlet hot air temperature at 100℃. The spray-dried product was collected and dried in air at 150℃ for 12 hours. The product was then calcined in air at 550℃ for 5 hours to obtain the catalyst product, which was designated as catalyst 1.

[0068] Example 2

[0069] Except for replacing 417.0g Mg(NO3)2·6H2O with 232.9g Ca(NO3)2·4H2O, the catalyst product was prepared according to the same steps as in Example 1 and is referred to as catalyst 2.

[0070] Example 3

[0071] 208.5 g Mg(NO3)2·6H2O, 93.0 g Zr(NO3)4·5H2O, and 113.0 g H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-current co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 8.2, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0072] Using the above-mentioned in-situ modified silicon source solution, the catalyst product was prepared according to the same steps as in Example 1, and is referred to as catalyst 3.

[0073] Example 4

[0074] 116.5 g Ca(NO3)2·4H2O, 93.0 g Zr(NO3)4·5H2O, and 113.0 g H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-current co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 8.1, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0075] 10 kg of Fe(NO3)3·9H2O and 904 g of Mn(NO3)2·4H2O were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron- and manganese-containing mixed solution was then precipitated in parallel with the ammonia solution at a precipitation temperature of 30℃ for 1 h, with the pH controlled at 8.0. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 155 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.6%, the slurrying temperature was 50℃, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0076] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 4.

[0077] Example 5

[0078] 625.5 g Mg(NO3)2·6H2O, 279.0 g Zr(NO3)4·5H2O, and 339.1 g H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-current co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 7.0, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0079] 10 kg of Fe(NO3)3·9H2O and 904 g of Mn(NO3)2·4H2O were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron- and manganese-containing mixed solution was then precipitated in parallel with the ammonia solution at a precipitation temperature of 70℃ for 1 h, with the pH controlled at 8.0. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 180 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.6%, the slurrying temperature was 40℃, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0080] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 5.

[0081] Example 6

[0082] 349.4 g of Ca(NO3)2·4H2O, 279.0 g of Zr(NO3)4·5H2O, and 339.1 g of H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 7.0, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0083] 10 kg of Fe(NO3)3·9H2O and 120.0 g of Nd(NO3)3·6H2O were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron- and neodymium-containing mixed solution was precipitated co-currently with the ammonia solution at a precipitation temperature of 10℃ for 1 h, with the pH controlled at 6.5. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 180 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.6%, the slurrying temperature was 60℃, and the slurrying time was 1.5 h to obtain the catalyst precursor slurry.

[0084] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 6.

[0085] Example 7

[0086] An in-situ modified silicon source solution was prepared according to Example 1.

[0087] 10 kg of Fe(NO3)3·9H2O and 449.6 g of Zn(NO3)2·6H2O were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron- and zinc-containing mixed solution was then precipitated co-currently with the ammonia solution at a precipitation temperature of 50℃ for 1 h, with the pH controlled at 6.5. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 180 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were then added sequentially to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.6%, the slurrying temperature was 30℃, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0088] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 7.

[0089] Example 8

[0090] An in-situ modified silicon source solution was prepared according to Example 2.

[0091] 10 kg of Fe(NO3)3·9H2O and 990.6 g of Ti(NO3)4 were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron- and titanium-containing mixed solution was precipitated co-currently with the ammonia solution at a precipitation temperature of 50 °C for 1 h, with the pH controlled at 7.2. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 180 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.7%, the slurrying temperature was 40 °C, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0092] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 8.

[0093] Example 9

[0094] 417.0 g Mg(NO3)2·6H2O, 186.0 g Zr(NO3)4·5H2O, and 226.1 g H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 1.2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-current co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 7.2, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0095] 10 kg of Fe(NO3)3·9H2O and 267.8 g of KVO3 were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron- and vanadium-containing mixed solution was precipitated together with the ammonia solution under co-current flow at a precipitation temperature of 50 °C for 1 h, with the pH controlled at 7.2. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 155 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K precursor aqueous solution. The K precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.7%, the slurrying temperature was 30 °C, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0096] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 9.

[0097] Example 10

[0098] 232.9 g of Ca(NO3)2·4H2O, 186.0 g of Zr(NO3)4·5H2O, and 226.1 g of H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 1.2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-current co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 7.2, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0099] 10 kg of Fe(NO3)3·9H2O and 1373.9 g of Al(NO3)3·9H2O were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron-aluminum mixed solution was precipitated in parallel with the ammonia solution at a precipitation temperature of 50℃ for 1 h, with the pH controlled at 7.2. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 155 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.7%, the slurrying temperature was 30℃, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0100] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 10.

[0101] Example 11

[0102] 208.5.0 g of Mg(NO3)2·6H2O, 279.0 g of Zr(NO3)4·5H2O, and 226.1 g of H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 7.5, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0103] 10 kg of Fe(NO3)3·9H2O and 190 g of Cu(NO3)2·3H2O were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron-copper mixed solution was then precipitated in parallel with the ammonia solution at a precipitation temperature of 50 °C for 1 h, with the pH controlled at 7.0. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 155 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.5%, the slurrying temperature was 30 °C, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0104] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 11.

[0105] Example 12

[0106] 938.2 g Mg(NO3)2·6H2O, 139.5 g Zr(NO3)4·5H2O, and 339.1 g H3BO3 were dissolved in deionized water to prepare a 10.0 kg ternary modifier solution. 2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 5 kg of deionized water to prepare an initial silicon source solution. The ternary modifier solution and the initial silicon source solution were subjected to a co-current co-precipitation reaction under stirring at a temperature of 50 °C, a pH of 7.0, and a precipitation time of 1 h to obtain an in-situ modified silicon source solution.

[0107] 10 kg of Fe(NO3)3·9H2O and 904 g of Mn(NO3)2·4H2O were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The iron- and manganese-containing mixed solution was then precipitated co-currently with the ammonia solution at 50 °C for 1 h, with the pH controlled at 8.0. After precipitation, the slurry was separated by a filter to obtain a catalyst precursor filter cake. 180 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare a K-auxiliary agent precursor aqueous solution. The K-auxiliary agent precursor aqueous solution and the modified silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The slurry concentration was 14.6%, the slurrying temperature was 30 °C, and the slurrying time was 1.5 h, yielding the catalyst precursor slurry.

[0108] The catalyst was dried and calcined according to Example 1 to obtain the finished catalyst product, which is designated as Catalyst 12.

[0109] Comparative Example 1

[0110] Except for the preparation of the binary modifier solution using 279.0g Zr(NO3)4·5H2O and 339.1g H3BO3, the catalyst product was prepared according to the same steps as in Example 1 and is referred to as Comparative Agent 1.

[0111] Comparative Example 2

[0112] Except for the preparation of the binary modifier solution using 625.5g Mg(NO3)2·6H2O and 339.1g H3BO3, the catalyst product was prepared according to the same steps as in Example 1 and is referred to as Comparative Agent 2.

[0113] Comparative Example 3

[0114] Except for the preparation of the binary modifier solution using 349.4g Ca(NO3)2·4H2O and 279.0g Zr(NO3)4·5H2O, the catalyst product was prepared according to the same steps as in Example 1 and is referred to as Comparative Agent 3.

[0115] Comparative Example 4

[0116] Except for the preparation of the binary modifier solution using 139.5g Zr(NO3)4·5H2O and 169.6g H3BO3, the catalyst product was prepared according to the same steps as in Example 1 and is referred to as Comparative Agent 4.

[0117] Comparative Example 5

[0118] Except for the preparation of the binary modifier solution using 312.7g Mg(NO3)2·6H2O and 169.6g H3BO3, the catalyst product was prepared according to the same steps as in Example 5, and was designated as Comparative Agent 5.

[0119] Comparative Example 6

[0120] Except for the preparation of the binary modifier solution using 174.7g Ca(NO3)2·4H2O and 139.5g Zr(NO3)4·5H2O, the catalyst product was prepared according to the same steps as in Example 5 and is referred to as Comparative Agent 6.

[0121] Comparative Example 7

[0122] Except for the preparation of the binary modifier solution using 279.0g Zr(NO3)4·5H2O and 339.1g H3BO3, the catalyst product was prepared according to the same steps as in Example 5 and was designated as Comparative Agent 7.

[0123] Comparative Example 8

[0124] Except for the preparation of the binary modifier solution using 349.4g Ca(NO3)2·4H2O and 339.1g H3BO3, the catalyst product was prepared according to the same steps as in Example 9 and is referred to as Comparative Agent 8.

[0125] Comparative Example 9

[0126] Except for the preparation of the binary modifier solution using 349.4g Ca(NO3)2·4H2O and 279.0g Zr(NO3)4·5H2O, the catalyst product was prepared according to the same steps as in Example 10 and is referred to as Comparative Agent 9.

[0127] Comparative Example 10

[0128] The catalyst was prepared according to the invention patent CN 107456976B and is designated as contrast agent 10.

[0129] Comparative Example 11

[0130] 2 kg of liquid potassium silicate (SiO2 content 25%) was dispersed in 15 kg of deionized water to prepare the initial silicon source solution.

[0131] 10 kg of Fe(NO3)3·9H2O, 190 g of Cu(NO3)2·3H2O, 417.0 g of Mg(NO3)2·6H2O, 186.0 g of Zr(NO3)4·5H2O, and 226.1 g of H3BO3 were dissolved in deionized water to prepare a 50 L solution. 12 kg of 25% ammonia solution was added to the deionized water to prepare a 30 L solution. The resulting mixed solution was then precipitated in parallel with the ammonia solution at 50 °C for 1 h, with the pH controlled at 7.0. After precipitation, the slurry was separated by a filter to obtain the catalyst precursor filter cake. 155 g of potassium nitrate was fully dissolved in 1.5 kg of deionized water to prepare an aqueous solution of the K auxiliary agent precursor. The K-auxiliary agent precursor aqueous solution and the initial silicon source solution were sequentially added to the catalyst precursor filter cake for slurrying. The mass concentration of the slurry was 14.5%, the slurrying temperature was 30℃, and the slurrying time was 1.5h to obtain the catalyst precursor slurry.

[0132] The catalyst was dried and calcined according to Example 1 to obtain the finished product, which is designated as Comparative Agent 11.

[0133] Test Example 1: Catalyst Composition Test

[0134] The catalysts 1-12 and contrast agents 1-11 were analyzed using an X-ray fluorescence spectrometer (XRF), and the results are shown in Table 1.

[0135] Table 1. Composition of each catalyst in the examples and comparative examples.

[0136]

[0137]

[0138] Test Example 2: Catalyst Performance Test

[0139] The catalysts 1-12 and the comparative agent 1-11 were subjected to catalytic reaction in a slurry bed reactor to evaluate the catalyst performance. The specific reaction conditions and results are shown in Tables 2 and 3.

[0140] Table 2 Test results of catalysts 1-12

[0141]

[0142]

[0143] Table 3 Test results of contrast agent 1-11

[0144]

[0145] As can be seen from the results in Tables 2 and 3, the Fischer-Tropsch iron-based catalyst (modified with a ternary modifier) ​​of the present invention has a higher specific surface area and pore volume. It is significantly superior to the Fischer-Tropsch iron-based catalyst (modified with a binary modifier or modified with a non-silicon source) prepared in the comparative example in terms of catalyst stability (deactivation rate) and anti-wear properties (chemical wear value). Moreover, the Fischer-Tropsch iron-based catalyst of the present invention also has a lower K loss rate during the Fischer-Tropsch synthesis process, and the catalytic activity is further improved. It also shows significant improvements in raw material conversion rate and product selectivity.

[0146] Unless otherwise specified, the terms used in this invention have the meanings commonly understood by those skilled in the art.

[0147] The embodiments described in this invention are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A modified Fischer-Tropsch iron-based catalyst comprising a SiO2 support, characterized in that, The SiO2 support is modified with a ternary modifier, which is composed of any one of Mg and Ca, Zr and B. The total mass of the ternary modifier is 10-60% of the SiO2 support, and the mass ratio of any one of Mg and Ca, Zr and B is 0.5-1.5:0.5-1.5:

1. The modified Fischer-Tropsch iron-based catalyst comprises the following components in the following mass ratio: Fe2O3: metal X1 additive: K additive: X2: SiO2 support = 100: 0.5~25: 0.1~5: 1~15: 5~30, wherein X1 represents one or more of the elements Ti, V, Cr, Mn, Cu, Zn, Al, and Nd, and X2 represents the ternary modifier; The preparation of the modified Fischer-Tropsch iron-based catalyst includes the following steps: S1: Prepare a ternary modifier aqueous solution by water-soluble salts of Mg or Ca, water-soluble salts of Zr and boric acid, and prepare an unmodified initial silicon source solution. The initial silicon source solution is an aqueous solution of potassium silicate, sodium silicate sol or ammonia silica sol, wherein the SiO2 concentration is 0.5-35% by mass percentage. S2: The modified silicon source solution is prepared by co-precipitation reaction of the ternary modifier aqueous solution and the initial silicon source solution; and S3: The modified Fischer-Tropsch iron-based catalyst is prepared using the modified silicon source solution.

2. The modified Fischer-Tropsch iron-based catalyst according to claim 1, characterized in that, The total concentration of any one of Mg and Ca, Zr and B in the aqueous solution of the ternary modifier is 0.2% to 5% by mass percentage.

3. The modified Fischer-Tropsch iron-based catalyst according to claim 1, characterized in that, The water-soluble salt is a nitrate.

4. The modified Fischer-Tropsch iron-based catalyst according to claim 1, characterized in that, The SiO2 concentration in the initial silicon source solution is 1-10% by mass percentage.

5. The modified Fischer-Tropsch iron-based catalyst according to claim 1, characterized in that, The reaction temperature of the co-precipitation reaction is 5–90°C, and the precipitation time is 0.5–5 h.

6. The modified Fischer-Tropsch iron-based catalyst according to any one of claims 1-5, characterized in that, The modified Fischer-Tropsch iron-based catalyst comprises the following components in the following mass ratio: Fe2O3: metal X1 additive: K additive: X2: SiO2 support = 100: 1~15: 1~5: 2~10: 10~25, wherein X1 represents one or more of the elements Ti, V, Cr, Mn, Cu, Zn, Al, and Nd, and X2 represents a ternary modifier.

7. The modified Fischer-Tropsch iron-based catalyst according to claim 6, characterized in that, The preparation of the modified Fischer-Tropsch iron-based catalyst includes the following steps: T1: A mixed aqueous solution is formed by the water-soluble salt of Fe and the water-soluble salt containing metal X1, and then co-precipitated with a precipitant to separate the resulting precipitate; T2: The precipitate is mixed with the precursor aqueous solution of K auxiliary agent and the modified silicon source solution modified by the ternary modifier and subjected to slurry treatment to obtain a catalyst precursor slurry; and T3: The catalyst precursor slurry is dried, shaped, and calcined.

8. The modified Fischer-Tropsch iron-based catalyst according to claim 7, characterized in that, In step T1, the water-soluble salt of Fe is a Fe nitrate; and / or The water-soluble salt containing metal X1 is a nitrate containing metal X1; and / or The mixed aqueous solution and the precipitant undergo a co-precipitation reaction in a parallel flow. The reaction temperature is 5–90°C, the precipitation time is 0.5–5 h, and the pH value is controlled to be 4–12 during the reaction.

9. The modified Fischer-Tropsch iron-based catalyst according to claim 7, characterized in that, The precipitant is one or more of ammonia, sodium carbonate, ammonium carbonate, and sodium hydroxide.

10. The modified Fischer-Tropsch iron-based catalyst according to claim 7, characterized in that, In step T2, the precursor of the K auxiliary agent is one or more of potassium nitrate, potassium carbonate, and potassium bicarbonate; and / or The pulping process is carried out at a temperature of 10–60°C for 0.5–5 hours.

11. The modified Fischer-Tropsch iron-based catalyst according to claim 10, characterized in that, The concentration of the precursor aqueous solution of the K auxiliary agent is 5-15% by mass percentage.

12. The modified Fischer-Tropsch iron-based catalyst according to claim 7, characterized in that, In step T3, the drying and molding process is spray drying, wherein the inlet air temperature is 150–350°C, the outlet air temperature is 90–205°C, and the drying time is 5–20 hours; and / or The roasting temperature is 300–700℃, and the roasting time is 3–12 hours.

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