Iron-based catalysts, their preparation methods and applications, and the FTO reaction

Abstract

This invention relates to the field of catalyst technology, specifically to an iron-based catalyst, its preparation method and application, and the FTO reaction. The catalyst comprises a support and an active component. The active component, expressed as an oxide, has the following general chemical formula: Fe 100 Mn a Nb b Cs c A d B e O x A is selected from Group VIII nonferrous metals and / or Group VIB elements; B is selected from La series elements; the value of a ranges from 30.0 to 130.0; the value of b ranges from 1.0 to 20.0; the value of c ranges from 0.1 to 10.0; the value of d ranges from 1.0 to 60.0; the value of e ranges from 0.1 to 10.0; x is the total number of oxygen atoms required to satisfy the oxidation states of each element in the catalyst. The iron-based catalyst of this invention exhibits excellent resistance to carbon deposition during use, and when used in the FTO reaction, it can achieve high CO feedstock conversion and C2-C4 olefin selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to an iron-based catalyst, its preparation method and application, and the FTO reaction. Background Technology

[0002] Iron-based catalysts commonly used in the direct synthesis of low-carbon olefins are highly susceptible to interference from their preparation process, additives, and treatment methods, which significantly impact their activity and selectivity. Alkali metal promoters, as important electronic promoters for Fe-based catalysts, have attracted considerable attention. Alkali metals exhibit a significant promoting effect on Fe-based catalysts in the Fischer-Tropsch synthesis, with the promoting efficiency roughly proportional to basicity. Mn promoters also possess electron-donating properties, altering the binding energy of species on the sample surface. Some studies suggest that MnO can promote the dissociation and adsorption of CO while weakening the adsorption of H2, thus inhibiting hydrogenation on the catalyst surface to some extent and thereby improving the selectivity of olefins in the product.

[0003] CN105854915A discloses a catalyst for the preparation of low-carbon olefins from syngas and its preparation method. The catalyst includes Mg, Fe, M, and K elements, where M is Zn, Al, or Mn. It is prepared by co-precipitation, atmospheric pressure crystallization, and finally impregnation with a K source. It is used for the direct hydrogenation of CO to low-carbon olefins, achieving a CO single-pass conversion greater than 70%, an alkene-to-olefin ratio (O / P) greater than 5.0, and a C5+ total hydrocarbon weight distribution less than 15 wt%. The catalyst preparation process is simple and reproducible, but the carbon monoxide conversion and low-carbon olefin selectivity are both relatively low. Summary of the Invention

[0004] The purpose of this invention is to provide a new iron-based catalyst and its preparation method. When this iron-based catalyst is used in the FTO reaction, it exhibits excellent catalytic activity, resulting in high carbon monoxide conversion and high selectivity for low-carbon olefins.

[0005] To achieve the above objectives, a first aspect of the present invention provides an iron-based catalyst comprising a support and an active component, wherein the active component, expressed as an oxide, has the following general chemical formula:

[0006] Fe 100 Mn a Nb b Cs c A d B e O x ,

[0007] A is selected from Group VIII nonferrous metals and / or Group VIB elements;

[0008] B is selected from the La series elements;

[0009] The value of 'a' ranges from 30.0 to 130.0;

[0010] The value of b ranges from 1.0 to 20.0;

[0011] The value of c ranges from 0.1 to 10.0;

[0012] The value of d ranges from 1.0 to 60.0;

[0013] The value of e ranges from 0.1 to 10.0;

[0014] x represents the total number of oxygen atoms required to satisfy the oxidation states of all elements in the catalyst.

[0015] A second aspect of the present invention provides a method for preparing the iron-based catalyst described herein, the method comprising:

[0016] (1) In the presence of a precipitant, a solution containing Fe source, Mn source, Nb source and A source undergoes a precipitation reaction;

[0017] (2) The precipitate obtained from the precipitation reaction in step (1) is mixed with the carrier source, Cs source solution, pH adjuster and B source solution in sequence, and then dried and calcined.

[0018] A third aspect of the present invention provides the application of the iron-based catalyst described herein in the FTO reaction.

[0019] A fourth aspect of the present invention provides an FTO reaction in which H2 and CO undergo a contact reaction in the presence of the iron-based catalyst described in the present invention.

[0020] Through the above technical solution, the new iron-based catalyst provided in this invention has excellent anti-carbon deposition properties when used, and can achieve high CO feed conversion rate and C2-C4 olefin selectivity when used in FTO reaction. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The first aspect of this invention provides an iron-based catalyst comprising a support and an active component, wherein the active component, expressed as an oxide, has the following general chemical formula:

[0023] Fe 100 Mn a Nb b Csc A d B e O x ,

[0024] A is selected from Group VIII nonferrous metals and / or Group VIB elements;

[0025] B is selected from the La series elements;

[0026] The value of 'a' ranges from 30.0 to 130.0;

[0027] The value of b ranges from 1.0 to 20.0;

[0028] The value of c ranges from 0.1 to 10.0;

[0029] The value of d ranges from 1.0 to 60.0;

[0030] The value of e ranges from 0.1 to 10.0;

[0031] x represents the total number of oxygen atoms required to satisfy the oxidation states of all elements in the catalyst.

[0032] In this invention, the active component of the iron-based catalyst contains elements Fe, Mn, Nb, Cs, A, and B. The active component is represented by oxides, which does not mean that all elements Fe, Mn, Nb, Cs, A, and B exist in the iron-based catalyst in oxide form. Fe, Mn, Nb, Cs, A, and B exist in at least one of the following forms: atomic, oxide, and carbide. The chemical formula representing the active component as an oxide in this invention refers only to the chemical formula of a composite oxide of Fe, Mn, Nb, Cs, A, and B. This chemical formula allows us to obtain the molar ratio of Fe, Mn, Nb, Cs, A, and B in the active component. The molar content of Fe, Mn, Nb, Cs, A, and B in the active component is the molar content of the corresponding elements provided by the corresponding raw materials during catalyst preparation.

[0033] The novel iron-based catalyst provided in this invention exhibits excellent resistance to carbon deposition during use, and when used in FTO reactions, it achieves high CO feedstock conversion and C2-C4 olefin selectivity.

[0034] According to the present invention, the specific types of Group VIII nonferrous metal elements and Group VIB elements are not particularly limited as long as the purpose of the present invention can be achieved. In some preferred embodiments, A is selected from at least one of Co, Ni, Cu, and Zn. The catalyst under this embodiment has better catalytic activity and resistance to carbon deposition.

[0035] According to the present invention, the specific selection of La-series elements is not particularly limited as long as the objectives of the invention can be achieved. In some preferred embodiments, B is selected from at least one of La, Ce, Pr, and Nd, preferably from La. The catalyst under this embodiment has better catalytic activity and resistance to carbon deposition.

[0036] According to the present invention, in some preferred embodiments, the value of 'a' ranges from 40.0 to 120.0, for example, 40.0, 50.0, 60.0, 70.0, 80.0, 90.0, 100.0, 120.0, or any combination of two of the above values. In this embodiment, the catalyst exhibits better synergistic effects between the active components and the support, thereby enhancing the catalyst's resistance to carbon deposition and its catalytic activity.

[0037] According to the present invention, in some preferred embodiments, the value of b ranges from 5.0 to 15.0, for example, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, or any range consisting of two of the above values. In this embodiment, the catalyst exhibits better synergistic effects between the active components and the support, thereby improving the catalyst's resistance to carbon deposition and its catalytic activity.

[0038] According to the present invention, in some preferred embodiments, the value of c ranges from 0.5 to 8.0, for example, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, or any combination of two of the above values. In this embodiment, the catalyst exhibits better synergistic effects between the active components and the support, thereby enhancing the catalyst's resistance to carbon deposition and its catalytic activity.

[0039] According to the present invention, in some preferred embodiments, the value of d ranges from 5.0 to 50.0, for example, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 12.0, 15.0, 20.0, 30.0, 40.0, 50.0, or any combination of two of the above values. In this embodiment, the catalyst exhibits better synergistic effects between the active components and the support, thereby improving the catalyst's resistance to carbon deposition and its catalytic activity.

[0040] According to the present invention, in some preferred embodiments, the value of e ranges from 0.5 to 8.0, for example, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, or any combination of two of the above values. In this embodiment, the catalyst exhibits better synergistic effects between the active components and the support, thereby enhancing the catalyst's resistance to carbon deposition and its catalytic activity.

[0041] According to the present invention, there is no particular limitation on the specific type of carrier as long as the purpose of the present invention can be achieved. In some preferred embodiments, the carrier is selected from at least one of silicon dioxide, aluminum oxide and titanium oxide.

[0042] According to some preferred embodiments of the present invention, the content of the support is 5-60% by weight, based on the total weight of the catalyst, for example, 5% by weight, 10% by weight, 20% by weight, 30% by weight, 40% by weight, 50% by weight, or any combination of two of the above values, preferably 40-60% by weight.

[0043] According to some preferred embodiments of the present invention, the content of the active component is 40-95 wt% based on the total weight of the catalyst, for example, 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 75 wt%, 85 wt%, 95 wt%, or any combination of two of the above values, preferably 40-60 wt%.

[0044] A second aspect of the present invention provides a method for preparing the iron-based catalyst described herein, the method comprising:

[0045] (1) In the presence of a precipitant, a solution containing Fe source, Mn source, Nb source and A source undergoes a precipitation reaction;

[0046] (2) The precipitate obtained from the precipitation reaction in step (1) is mixed with the carrier source, Cs source solution, pH adjuster and B source solution in sequence, and then dried and calcined.

[0047] The iron-based catalyst prepared in this invention exhibits excellent resistance to carbon deposition during use, and when used in the FTO reaction, it can achieve high CO feed conversion and C2-C4 olefin selectivity.

[0048] According to the present invention, the solution containing Fe source, Mn source, Nb source and A source refers to a solution formed by a good solvent and Fe source, Mn source, Nb source and A source. Specifically, the Fe source, Mn source, Nb source and A source can be mixed with a good solvent to obtain four groups of materials, and then the four groups of materials can be mixed to obtain a solution containing Fe source, Mn source, Nb source and A source; alternatively, the Fe source, Mn source, Nb source and A source can be simultaneously added to a good solvent and mixed to obtain a solution containing Fe source, Mn source, Nb source and A source; alternatively, the Fe source can be mixed with a good solvent to obtain material I, the Nb source can be mixed with a good solvent to obtain material II, and the Mn source and A source can be mixed with a good solvent to obtain material III, and then material I, material II and material III can be mixed to obtain a solution containing Fe source, Mn source, Nb source and A source. However, the formation of a solution containing Fe source, Mn source, Nb source and A source is not limited to the above methods. The selection of the good solvent is not particularly limited as long as the purpose of the present invention can be achieved; the good solvent in the present invention is selected from water.

[0049] According to the present invention, the contents of Fe source, Mn source, Nb source and A source in the solution can be selected according to the contents of Fe, Mn, Nb and A of the corresponding active components in the iron-based catalyst; the amount of water used is only required to dissolve Fe source, Mn source, Nb source and A source and to ensure the smooth progress of the precipitation reaction.

[0050] According to the present invention, there are no special restrictions on the selection of Fe source, Mn source, Nb source and A source, and they can be salts corresponding to Fe, Mn, Nb and A, such as nitrates and / or oxalates.

[0051] According to the present invention, the type of precipitant is not particularly limited as long as the purpose of the present invention can be achieved. In some embodiments, in step (1), the precipitant is an alkaline precipitant, preferably at least one of urea, ammonia and ammonium bicarbonate.

[0052] According to the present invention, in some embodiments, in step (1), the amount of the precipitant is 30-50% of the total weight of the added Fe source, Mn source, Nb source and A source.

[0053] According to the present invention, in some embodiments, the precipitation reaction conditions in step (1) include: a precipitation temperature of 70-95°C.

[0054] According to the present invention, in some embodiments, in step (1), the precipitation reaction conditions include a precipitation time of 10-60 minutes.

[0055] According to the present invention, the precipitate obtained by the precipitation reaction in step (1) can be obtained by washing with water and separating the precipitate. The present invention has no special limitations on this.

[0056] According to the present invention, the type of support source is not particularly limited as long as the objective of the invention can be achieved. In some embodiments, the support source is selected from the sol corresponding to the support, such as silica sol, alumina sol, or titanium sol. The catalyst obtained by this embodiment has superior resistance to carbon deposition and catalytic activity.

[0057] According to the present invention, the Cs source solution refers to a solution formed by mixing a Cs source with a corresponding good solvent. The amount of good solvent is not particularly limited, as long as it can fully dissolve the Cs source. The good solvent in the present invention is water. The choice of Cs source is not particularly limited and can be a Cs salt or a Cs hydroxide.

[0058] According to the present invention, the B source solution refers to a solution formed by mixing the B source with a corresponding good solvent. The amount of good solvent is not particularly limited, as long as it can fully dissolve the B source. The selection of the B source is not particularly limited. The good solvent in the present invention is water, which can be a B salt, such as a nitrate.

[0059] According to the present invention, the contents of Cs source and B source can be selected according to the contents of the corresponding Cs and B active components in the iron-based catalyst.

[0060] According to some preferred embodiments of the present invention, in step (2), the amount of pH adjuster added is such that the pH value of the system is 5-6. The catalyst obtained using this embodiment has superior resistance to carbon deposition and catalytic activity.

[0061] According to the present invention, as long as the purpose of the present invention can be achieved, the drying and calcination conditions in step (2) are not particularly limited. Preferably, the drying is spray drying, wherein spray drying can also make the solid material of microspheres formed; preferably, the calcination temperature is 300-550°C; preferably, the calcination time is 0.5-5 hours.

[0062] According to some preferred embodiments of the present invention, the preparation method of the iron-based catalyst further includes reduction treatment and carbonization treatment of the solid material obtained by calcination. Using the aforementioned embodiments, the prepared catalyst not only possesses good catalytic activity but also excellent resistance to carbon deposition, and exhibits high selectivity for C2-C4 olefins in the FTO reaction.

[0063] According to the present invention, in some preferred embodiments, the reducing atmosphere for the reduction treatment comprises H2 and an inert gas, preferably with a volume concentration of H2 of 1-20%, for example, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, or any combination of two of the above values. Using the aforementioned embodiments, the catalyst prepared not only exhibits good catalytic activity but also excellent resistance to carbon deposition, and its application in the FTO reaction of C2-C4 olefins also demonstrates high selectivity.

[0064] According to some preferred embodiments of the present invention, the conditions for the reduction treatment include a pressure of 0-2 MPa.

[0065] According to some preferred embodiments of the present invention, the conditions for the reduction treatment include: a solid loading of 3000-6000 mL·h. -1 ·g -1 The solid substance here refers to the solid substance obtained after roasting.

[0066] According to some preferred embodiments of the present invention, the conditions for the reduction treatment include a heating rate of 1-15°C / minute.

[0067] According to some preferred embodiments of the present invention, the conditions for the reduction treatment include a reduction temperature of 200-450°C.

[0068] According to some preferred embodiments of the present invention, the conditions for the reduction process include a reduction time of 12-48 hours.

[0069] According to some particularly preferred embodiments of the invention, the carbonization atmosphere of the carbonization process comprises low-carbon alkanes and inert gases.

[0070] According to some particularly preferred embodiments of the invention, the volume concentration of low-carbon alkanes in the carbonization atmosphere is 5-25%, for example, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 23%, 25%, or any combination of two of the above values.

[0071] According to the present invention, in some particularly preferred embodiments, the low-carbon alkanes are preferably C2-C4 alkanes (e.g., ethane, propane, butane). The catalyst prepared using the foregoing embodiments not only exhibits good catalytic activity but also excellent resistance to carbon deposition, and its use in the FTO reaction for producing C2-C4 olefins also demonstrates high selectivity.

[0072] According to some particularly preferred embodiments of the present invention, the carbonization treatment conditions include a pressure of 0-2 MPa.

[0073] According to some particularly preferred embodiments of the present invention, the conditions for carbonization treatment include: a solid loading of 3000–6000 mL·h. -1 ·g -1 The solid substance here refers to the solid substance obtained after reduction treatment.

[0074] According to some particularly preferred embodiments of the present invention, the carbonization treatment conditions include a heating rate of 3-20°C / minute.

[0075] According to some particularly preferred embodiments of the present invention, the carbonization treatment conditions include a carbonization temperature of 200-450°C.

[0076] According to some particularly preferred embodiments of the present invention, the carbonization treatment conditions include a carbonization time of 12-48 hours.

[0077] A third aspect of the present invention provides the application of the iron-based catalyst described herein in the FTO reaction.

[0078] When the iron-based catalyst of this invention is used in the FTO reaction, the feedstock CO has a high conversion rate and C2-C4 olefins have high selectivity, and the catalyst has a lower carbon deposition during long-term use.

[0079] A fourth aspect of the present invention provides an FTO reaction in which H2 and CO undergo a contact reaction in the presence of the iron-based catalyst described in the present invention.

[0080] According to the present invention, preferably, the H2 / CO molar ratio is 0.1-5.

[0081] According to the present invention, the conditions for the contact reaction are not particularly limited as long as the purpose of the present invention can be achieved. Preferably, the temperature during the contact reaction is 200-400°C; preferably, the reaction pressure during the contact reaction is 0.5-10 MPa; and preferably, the volume hourly space velocity (VHSV) of the H2 and CO mixture is 100-8000 mL·h. -1 ·g -1 .

[0082] The present invention will be described in detail below through embodiments.

[0083] The iron-based catalysts prepared in the examples and comparative examples were used respectively to carry out the direct synthesis of low-carbon olefins from syngas under the following conditions.

[0084] The reactor and process conditions are as follows:

[0085] millimeter fluidized bed reactor

[0086] Reaction temperature 360℃

[0087] Reaction pressure 1.2 MPa

[0088] The catalyst loading amount is equivalent to 80g of the catalyst before reduction.

[0089] Based on the amount of catalyst before reduction, the catalyst loading is 4500 mL·h. -1 ·g -1

[0090] Raw material ratio (moles): H2 / CO = 1.8 / 1.

[0091] Example 1

[0092] Take 568.9 g of ferric nitrate nonahydrate, add 1000 g of water to dissolve, to obtain material I; take 37.9 g of niobium oxalate, add 100 g of water and heat to dissolve, to obtain material II; take 201.6 g of 50 wt% manganese nitrate and 17.0 g of copper nitrate trihydrate in the same container, add 100 g of water, stir and dissolve to obtain material III;

[0093] Materials I, II, and III were mixed, and 250 grams of urea were added. The mixture was heated to 90°C with stirring to induce a precipitation reaction, and maintained at 90°C for 30 minutes. The precipitate was then obtained by washing with water and separating the precipitate.

[0094] 423.8 g of 40% (by weight) silica sol material was added to the above precipitate under stirring, followed by 50 g of a solution containing 1.05 g of CsOH. The pH of the slurry was adjusted with ammonia water to make the pH of the mixed slurry = 6.0. After stirring evenly, 50 g of an aqueous solution containing 3.0 g of lanthanum nitrate hexahydrate was added and stirred thoroughly to obtain the slurry.

[0095] The thoroughly stirred slurry was granulated into microspheres in a spray dryer, and then calcined at 500°C for 2.0 hours in a rotary calcining furnace with an inner diameter of 89 mm and a length of 1700 mm (φ89×1700 mm). The resulting solid was then subjected to reduction treatment: a 10% (H2) volume concentration H2 / N2 mixture was used, and the temperature was increased to 380°C at a rate of 5°C / min. The reduction was carried out at a pressure of 0.6 MPa, a solid loading of 80 g, and a catalyst loading of 5500 mL·h. -1 ·g -1 The mixture was kept at 380℃ for 24 hours. Finally, the resulting solid was carbonized: a C2H6 / N2 mixture with a volume concentration of 15% (C2H6) was used, and the temperature was increased to 380℃ at a rate of 10℃ / min. The carbonization was carried out at a pressure of 0.6MPa, a solid loading of 80g, and a solid loading rate of 5500mL·h. -1 ·g -1 The catalyst was carbonized at 380℃ for 24 hours to obtain an iron-based catalyst.

[0096] The iron-based catalyst prepared has the following composition (active components are expressed in the form of oxides): 50 wt% Fe 100 Mn 40.0 Nb 5.0 Cs 0.5 Cu 5.0 La 0.5 O x +50% by weight SiO2.

[0097] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0098] Example 2

[0099] Take 568.9 g of ferric nitrate nonahydrate, add 1000 g of water to dissolve, to obtain material I; take 76 g of niobium oxalate, add 200 g of water and heat to dissolve, to obtain material II; take 252 g of 50 wt% manganese nitrate and 20.5 g of copper nitrate trihydrate in the same container, add 100 g of water, stir and dissolve to obtain material III;

[0100] Materials I, II, and III were mixed, and 300 grams of urea were added. The mixture was heated to 80°C with stirring to induce a precipitation reaction, and then maintained at 90°C for 40 minutes. The precipitate was then obtained by washing with water and separating the precipitate.

[0101] Add 490g of 40% (by weight) silica sol material to the above precipitate while stirring, then add 50g of solution containing 8.5g of CsOH, adjust the pH of the above slurry with ammonia water to make the pH of the mixed slurry = 6.0, stir evenly, add 150g of aqueous solution containing 12.2g of lanthanum nitrate hexahydrate, and stir thoroughly to obtain the slurry;

[0102] The thoroughly stirred slurry was granulated into microspheres in a spray dryer, and then calcined at 500°C for 2.0 hours in a rotary calcining furnace with an inner diameter of 89 mm and a length of 1700 mm (φ89×1700 mm). The resulting solid was then subjected to reduction treatment: a 15% (H2) volume concentration H2 / N2 mixture was used to raise the temperature to 400°C at a rate of 10°C / min; the temperature was maintained at 1 MPa, a solid loading of 80 g, and a solid loading rate of 5000 mL·h. -1 ·g -1 The mixture was kept at 400℃ for 24 hours. Finally, the resulting solid was carbonized: a C2H6 / N2 mixture with a volume concentration of 20% (C2H6) was used, and the temperature was increased to 400℃ at a rate of 15℃ / min. The carbonization was carried out at a pressure of 1MPa, a solid loading of 80g, and a solid loading of 5000mL·h. -1 ·g -1 The iron-based catalyst was obtained by maintaining the temperature at 400℃ for 24 hours.

[0103] The iron-based catalyst prepared has the following composition (active components are expressed in the form of oxides): 50 wt% Fe 100 Mn 50.0 Nb 10.0 Cs 4.0 Cu 6.0 La 2.0 O x +50% by weight SiO2.

[0104] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0105] Example 3

[0106] Take 568.9 g of ferric nitrate nonahydrate, add 1000 g of water to dissolve, to obtain material I; take 45.5 g of niobium oxalate, add 120 g of water and heat to dissolve, to obtain material II; take 201.6 g of 50 wt% manganese nitrate and 41 g of cobalt nitrate hexahydrate in the same container, add 120 g of water, stir and dissolve to obtain material III;

[0107] Materials I, II, and III were mixed, and 250 grams of urea were added. The mixture was heated to 90°C with stirring to induce a precipitation reaction, and maintained at 90°C for 30 minutes. The precipitate was then obtained by washing with water and separating the precipitate.

[0108] Add 434 g of 40% (by weight) titanium sol material to the above precipitate under stirring, then add 50 g of solution containing 1.05 g of CsOH, adjust the pH of the above slurry with ammonia water to make the pH of the mixed slurry = 6.0, stir evenly, add 50 g of aqueous solution containing 3.0 g of lanthanum nitrate hexahydrate, and stir thoroughly to obtain the slurry;

[0109] The thoroughly stirred slurry was granulated into microspheres in a spray dryer, and then calcined at 550°C for 2.0 hours in a rotary calcining furnace with an inner diameter of 89 mm and a length of 1700 mm (φ89×1700 mm). The resulting solid was then subjected to reduction treatment: a 10% (H2) volume concentration H2 / N2 mixture was used, and the temperature was increased to 380°C at a rate of 5°C / min. The reduction was carried out at a pressure of 0.6 MPa, a solid loading of 80 g, and a catalyst loading of 4500 mL·h. -1 ·g -1 The mixture was kept at 380℃ for 24 hours; finally, the resulting solid was carbonized: using a C2H6 / N2 mixed gas with a volume concentration of 18% (C3H8), the temperature was increased to 380℃ at a rate of 10℃ / min, under a pressure of 0.6MPa, a solid loading of 80g, and a solid loading of 4500mL·h. -1 ·g -1 The iron-based catalyst was obtained by maintaining the temperature at 380℃ for 24 hours.

[0110] The iron-based catalyst prepared has the following composition (active components are expressed in the form of oxides): 50 wt% Fe 100 Mn 40.0 Nb 6.0 Cs 0.5 Co 10.0 La 0.5 O x +50% by weight TiO2.

[0111] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0112] Example 4

[0113] The method is the same as in Example 1, except that:

[0114] Take 568.9 g of ferric nitrate nonahydrate, add 1000 g of water to dissolve, to obtain material I; take 37.9 g of niobium oxalate, add 100 g of water and heat to dissolve, to obtain material II; take 201.6 g of 50 wt% manganese nitrate and 1.05 g of CsOH, add 100 g of water and stir to dissolve, to obtain material III.

[0115] Materials I, II, and III were mixed, and 250 grams of urea were added. The mixture was heated to 90°C with stirring to induce a precipitation reaction, and maintained at 90°C for 30 minutes. The precipitate was then obtained by washing with water and separating the precipitate.

[0116] Add 423.8 g of 40% (by weight) silica sol material to the above precipitate while stirring, then add 100 g of a solution containing 17.0 g of copper nitrate trihydrate, adjust the pH of the above slurry with ammonia water to make the pH of the mixed slurry = 6.0, stir evenly, add 50 g of an aqueous solution containing 3.0 g of lanthanum nitrate hexahydrate, and stir thoroughly to obtain the slurry;

[0117] The remaining steps are the same as in Example 1, and the iron-based catalyst is finally obtained.

[0118] The iron-based catalyst prepared has the following composition (active components are expressed in the form of oxides): 50 wt% Fe 100 Mn 40.0 Nb 5.0 Cs 0.5 Cu 5.0 La 0.5 O x +50% by weight SiO2.

[0119] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0120] Example 5

[0121] The method is the same as in Example 1, except that:

[0122] Without carbonization, all other steps are the same, i.e., the iron-based catalyst is directly obtained after reduction treatment.

[0123] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0124] Example 6

[0125] The method is the same as in Example 1, except that:

[0126] The iron-based catalyst was obtained by replacing the 15% (C2H6) volume concentration of the C2H4 / N2 mixture with a 15% (ethylene) volume concentration of the C2H4 / N2 mixture, while keeping the other steps the same.

[0127] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0128] Example 7

[0129] The method is the same as in Example 1, except that:

[0130] The iron-based catalyst was obtained by replacing the 15% (C2H6) volume concentration C2H6 / N2 mixture with a 40% (C2H6) volume concentration C2H6 / N2 mixture, while keeping the other steps the same.

[0131] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0132] Example 8

[0133] The method is the same as in Example 1, except that:

[0134] The catalyst was obtained by replacing the 10% (H2) volume concentration of the H2 / N2 mixture with a 30% (H2) volume concentration of the H2 / N2 mixture, while keeping the other steps the same.

[0135] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0136] Comparative Example 1

[0137] Take 568.9 g of ferric nitrate nonahydrate, add 1000 g of water to dissolve, and obtain material I. Take 201.6 g of 50 wt% manganese nitrate and 17.0 g of copper nitrate trihydrate in the same container, add 100 g of water, stir and dissolve to obtain material III.

[0138] Materials I and III were mixed, and 250 grams of urea were added. The mixture was heated to 90°C with stirring to induce a precipitation reaction, and then kept at 90°C for 30 minutes. The precipitate was then obtained by washing with water and separating the precipitate.

[0139] 423.8 g of 40% (by weight) silica sol material was added to the above precipitate under stirring, followed by 50 g of a solution containing 1.1 g of CsOH. The pH of the slurry was adjusted with ammonia water to make the pH of the mixed slurry = 6.0. After stirring evenly, 50 g of an aqueous solution containing 3.0 g of lanthanum nitrate hexahydrate was added and stirred thoroughly to obtain the slurry.

[0140] The thoroughly stirred slurry was subjected to microsphere formation in a spray dryer, and finally calcined at 500°C for 2.0 hours in a rotary kiln with an inner diameter of 89 mm and a length of 1700 mm (φ89×1700 mm); afterwards

[0141] The obtained solid was subjected to reduction treatment: a 10% (H2) volume concentration H2 / N2 mixture was used, and the temperature was increased to 380℃ at a rate of 5℃ / min; the temperature was maintained at 0.6 MPa, a solid loading of 80 g, and a solid loading rate of 5500 mL·h. -1 ·g -1 The solid was kept at 380℃ for 24 hours; finally, the obtained solid was carbonized: a C2H6 / N2 mixture with a volume concentration of 15% (C2H6) was used, and the temperature was increased to 380℃ at a rate of 10℃ / min, under a pressure of 0.6MPa, a solid loading of 80g, and a solid loading of 5500mL·h. -1 ·g -1 The iron-based catalyst was obtained by maintaining the temperature at 380℃ for 24 hours.

[0142] The iron-based catalyst prepared has the following composition (active components are expressed in the form of oxides): 50 wt% Fe 100 Mn 40.0 Cs 0.5 Cu 5.0 La 0.5 O x +50% by weight SiO2

[0143] The prepared iron-based catalyst was used to directly prepare low-carbon olefins from syngas. The reaction was run for 300 hours, and the results are shown in Table 1.

[0144] Table 1

[0145]

[0146]

[0147] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An iron-based catalyst, characterized in that, The catalyst comprises a support and an active component, the chemical formula of which, in atomic ratios, is expressed as an oxide, as follows: Fe 100 Mn a Nb b Cs c A d B e O x , A is selected from Group VIII nonferrous metals and / or Cu; B is selected from the La series elements; The value of 'a' ranges from 30.0 to 130.0; The value of b ranges from 1.0 to 20.0; The value of c ranges from 0.1 to 10.0; The value of d ranges from 1.0 to 60.0; The value of e ranges from 0.1 to 10.0; x represents the total number of oxygen atoms required to satisfy the oxidation states of all elements in the catalyst.

2. The catalyst according to claim 1, wherein, A is selected from at least one of Co, Ni, and Cu; and / or B is selected from at least one of La, Ce, Pr, and Nd.

3. The catalyst according to claim 1, wherein, The value of 'a' ranges from 40.0 to 120.0; and / or The value of b ranges from 5.0 to 15.0; and / or The value of c ranges from 0.5 to 8.0; and / or The value of d ranges from 5.0 to 50.0; and / or The value of e ranges from 0.5 to 8.

0.

4. The catalyst according to claim 1, wherein, The carrier is selected from at least one of silica, alumina, and titanium dioxide; and / or Based on the total weight of the catalyst, the content of the support is 5-60% by weight.

5. A method for preparing the catalyst according to any one of claims 1-4, characterized in that, The preparation method includes: (1) In the presence of a precipitant, a solution containing Fe source, Mn source, Nb source and A source undergoes a precipitation reaction; (2) The precipitate obtained from the precipitation reaction in step (1) is mixed with the carrier source, Cs source solution, pH adjuster and B source solution in sequence, and then dried and calcined.

6. The preparation method according to claim 5, wherein, The preparation method also includes reducing and carbonizing the solid material obtained by calcination.

7. The method according to claim 6, wherein, The reducing atmosphere for the reduction process includes H2 and inert gases; and / or The conditions for reduction treatment include: a pressure of 0-2 MPa; and / or a solid loading of 3000-6000 mL·h. -1 •g -1 ; and / or, the heating rate is 1-15℃ / min; and / or, the reduction temperature is 200-450℃; and / or, the reduction time is 12-48 hours.

8. The method according to claim 7, wherein, The volume concentration of H2 in the reducing atmosphere is 1-20%.

9. The method according to claim 6, wherein, The carbonization atmosphere of the carbonization process includes low-carbon alkanes and inert gases; and / or The conditions for carbonization treatment include: a pressure of 0-2 MPa; and / or a solid loading of 3000-6000 mL·h. -1 •g -1 ; and / or, the heating rate is 3-20℃ / min; and / or, the carbonization temperature is 200-450℃; and / or, the carbonization time is 12-48 hours.

10. The method according to claim 9, wherein, Low-carbon alkanes are C2-C4 alkanes; and / or The volume concentration of low-carbon alkanes in the carbonized atmosphere is 5-25%.

11. The preparation method according to claim 5, wherein, In step (1), the precipitant is an alkaline precipitant; and / or In step (1), the amount of the precipitant used is 30-50% of the total weight of the Fe source, Mn source, Nb source and A source; and / or In step (1), the precipitation reaction conditions include: a precipitation temperature of 70-95℃; and / or a precipitation time of 10-60 minutes; and / or In step (2), the carrier source is selected from the sol corresponding to the carrier; and / or In step (2), the amount of pH adjuster added is such that the pH value of the system is 5-7.

12. The method according to claim 11, wherein, In step (1), the precipitant is at least one of urea, ammonia and ammonium bicarbonate.

13. The use of the iron-based catalyst according to any one of claims 1-4 in the FTO reaction.

14. An FTO reaction, characterized in that, The reaction comprises: H2 reacting with CO in the presence of the iron-based catalyst described in any one of claims 1-4.

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