A catalyst for directly preparing olefins from synthesis gas, and a preparation method and application thereof

Abstract

The application discloses a catalyst for directly preparing olefins from synthesis gas, a preparation method and application thereof. The catalyst comprises 20-50 parts of a carrier and 50-80 parts of an active component by weight, and the active component comprises a composition with a chemical formula as follows: Fe 100 Mn a B b Co c S c O x in an atomic ratio. The catalyst is suitable for a reaction for directly preparing olefins from synthesis gas, and has the advantages of high CO utilization rate and high olefin selectivity.

Description

Technical Field

[0001] This invention belongs to the field of syngas-to-olefins production, specifically relating to a catalyst for the direct production of olefins from syngas, its preparation method, and its application. Background Technology

[0002] The direct conversion of syngas into organic compounds generally refers to the Fischer-Tropsch reaction of syngas (CO and H2) under the action of a catalyst, yielding a mixture of various organic products, water, and CO2. Depending on the reaction temperature, the Fischer-Tropsch process can be divided into low-temperature Fischer-Tropsch and high-temperature Fischer-Tropsch. Low-temperature Fischer-Tropsch generally refers to Fischer-Tropsch synthesis at 200-280℃, with products mainly consisting of diesel fractions and waxy saturated alkanes. High-temperature Fischer-Tropsch generally refers to Fischer-Tropsch synthesis at reaction temperatures exceeding 300℃, with products mainly consisting of alkenes and alkanes with carbon chain lengths less than 20. There are three main types of industrially significant Fischer-Tropsch catalysts. One type is nickel-based catalysts suitable for methane production. Another type is cobalt-based catalysts suitable for low-temperature Fischer-Tropsch processes for producing high-chain saturated oils and waxes. Patent CN110252358A describes a cobalt catalyst and its preparation method, as well as a method for Fischer-Tropsch synthesis of Fischer wax. The third type is iron-based catalysts suitable for both low-temperature Fischer-Tropsch production of high-chain saturated alkanes and high-temperature Fischer-Tropsch production of gasoline fractions and light olefins. Patent CN106607059A describes an Fe-Mn catalyst for the direct preparation of low-carbon olefins from syngas and its preparation method.

[0003] For Fischer-Tropsch catalysts, whether cobalt-based or iron-based, sulfur poisoning is a major cause of deactivation, especially for cobalt, which is more sensitive to sulfur and more prone to poisoning, rendering the entire cobalt-containing catalyst unusable. For iron-containing catalysts, besides its activity in the hydrogenation of CO to produce various organic compounds, iron is also the main active component in the water-gas conversion process. Therefore, a problem with iron-based Fischer-Tropsch catalysts is the low utilization rate of CO in the syngas, with a significant portion of CO being converted into CO2 in the water-gas reaction.

[0004] Therefore, existing catalysts for the direct production of olefins from Fischer-Tropsch synthesis suffer from low CO utilization and low olefin selectivity to varying degrees. Further research and development of new catalysts for the direct production of olefins from syngas to address these issues is of great significance to this field. Summary of the Invention

[0005] To address the problems of low CO utilization and low olefin selectivity in existing technologies, this invention provides a catalyst for the direct preparation of olefins from syngas, its preparation method, and its applications. The catalyst is suitable for reactions involving the direct preparation of olefins from syngas, particularly for syngas with high CO / H2 ratios and containing a certain amount of CO2, exhibiting advantages such as high CO utilization and high olefin selectivity.

[0006] The first aspect of the present invention provides a catalyst for the direct preparation of olefins from syngas, wherein the catalyst comprises, by weight, 20-50 parts of a support and 50-80 parts of an active component;

[0007] On an atomic basis, the active component comprises a composition with the following chemical formula: Fe 100 Mn a B b Co c S c O x ;

[0008] Wherein, B includes at least one selected from alkali metals.

[0009] The value of a ranges from 3 to 150;

[0010] The value of b ranges from 0.1 to 10;

[0011] The value of c ranges from 0.05 to 2;

[0012] x represents the total number of oxygen atoms required to satisfy the oxidation states of all elements in the catalyst.

[0013] According to the present invention, the support comprises at least one of oxides of Si and Al.

[0014] According to the present invention, B includes at least one of Na, K, Rb, and Cs.

[0015] According to the present invention, based on XPS characterization results, the molar ratio of Co to S on the catalyst surface is 5 to 10:1.

[0016] According to the present invention, the catalyst is microsphere-shaped.

[0017] A second aspect of the present invention provides a method for preparing the catalyst, the method comprising the following steps:

[0018] (1) Soluble Fe salt and precipitant were flowed together to obtain precipitate I;

[0019] (2) The precipitate I, Mn salt, carrier, alkali metal source and CoSO4 are mixed and pulped to obtain slurry II;

[0020] (3) Spray dry and calcinate the slurry II from step (2) to obtain the catalyst.

[0021] According to the present invention, the soluble Fe salt in step (1) includes at least one of ferric nitrate, ferrous nitrate, ferric chloride, ferrous chloride, ferric citrate, ferrous citrate, ferric acetate, and ferrous acetate; the precipitant includes at least one of ammonia, potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide.

[0022] According to the present invention, the Mn salt in step (2) includes at least one of manganese nitrate, manganese acetate, and manganese citrate. The alkali metal source in step (2) includes at least one of an alkali metal-containing base and a salt.

[0023] According to the present invention, preferably, in step (2), an acid-base regulator is added to adjust the pH of slurry II to 1-5; the acid-base regulator is selected in accordance with conventional methods, and ammonia is preferred.

[0024] According to the present invention, preferably, the solid content in the slurry obtained in step (2) is 15-45% by weight.

[0025] According to the present invention, in step (2), precipitate I and Mn salt are first mixed and dissolved, and then mixed with the carrier, alkali metal source and CoSO4 and pulped. The temperature of the mixing and dissolving is 60-90°C.

[0026] According to the present invention, the spray forming equipment in step (3) is a spray dryer.

[0027] According to the present invention, the roasting temperature in step (3) is 450-700°C; the roasting time is 0.3-5h; and the roasting atmosphere is a mixture of nitrogen and air, preferably with a nitrogen to air volume ratio of 2-5:1.

[0028] According to the present invention, the hot air temperature for spray drying in step (3) is 150–350°C. Further, the hot air medium for spray drying is a mixture of air and a non-oxygen gas; preferably, the volume ratio of air to non-oxygen gas in the mixture is 1:2–5. The non-oxygen gas is preferably nitrogen.

[0029] The third aspect of the present invention provides the application of the above-described catalyst or the catalyst prepared by the above-described method in the direct synthesis of olefins from syngas.

[0030] According to the present invention, the composition of the synthesis gas includes CO, CO2 and hydrogen; preferably, the volume ratio of CO, CO2 and hydrogen is 1:0.1 to 0.3:0.6 to 1.8.

[0031] According to the present invention, the reaction temperature is 300–400°C; the reaction pressure is 0.5–8.0 MPa; and the catalyst loading (volume hourly space velocity) is 3000–12000 h⁻¹. -1 .

[0032] Compared with the prior art, the main advantages of this invention are as follows:

[0033] (1) The catalyst of the present invention comprises, by weight, 20-50 parts of support and 50-80 parts of active component; by atomic ratio, the active component comprises a composition with the following chemical formula: Fe 100 Mn a B b Co c S c O x This invention utilizes a specific ratio of Co and S elements in the composition of an Fe-Mn catalyst, further ensuring that the Co and S elements on the catalyst surface are distributed within a certain ratio range. This catalyst is particularly suitable for olefin production reactions involving high CO / H2 ratios and containing a certain amount of CO2 from syngas. When used for the direct production of olefins from syngas, this catalyst offers advantages such as high CO utilization and high olefin selectivity.

[0034] (2) In the preparation method of the catalyst of the present invention, CoSO4 is added during the preparation of Fe-Mn catalyst to achieve Co and S doping. The preparation process is controlled, especially the selection of calcination atmosphere and spray forming atmosphere, so that Co and S on the catalyst surface are distributed in a certain proportion range. This catalyst is particularly suitable for the synthesis gas conversion to olefins reaction with high CO / H2 and a certain amount of CO2.

[0035] (3) The catalyst of this invention is suitable for the direct preparation of olefins from syngas, especially for the conversion of syngas with high CO / H2 ratios and a certain amount of CO2 to olefins. When applied to the direct preparation of olefins from syngas, the catalyst of this invention significantly improves the CO conversion rate and the C content in the products. 2+ Selectivity of olefins. Detailed Implementation

[0036] In this invention, the elemental analysis of the catalyst surface was performed using an EscalLab Xi+ X-ray photoelectron spectroscopy (XPS) instrument.

[0037] In this invention, CO conversion rate (%) is expressed as a mass fraction.

[0038] In this invention, C2 + Olefin selectivity (%) is expressed as a mass fraction.

[0039] In this invention, C2 + Alkenes are alkenes with 2 to 20 carbon atoms.

[0040] In this invention, the catalyst evaluation methods for Examples 1-6 and Comparative Examples 2-4 are as follows:

[0041] The catalyst is reduced using an in-situ reduction method. After the reduction is complete, the process conditions are switched directly to the synthesis reaction conditions in the reactor used for the reduction to start the reaction.

[0042] Reactor specifications: Millimeter fluidized bed reactor;

[0043] Catalyst loading: 50 grams;

[0044] The reduction conditions are: temperature 450℃;

[0045] Pressure 0.1 MPa;

[0046] Catalyst loading (standard volume hourly space velocity) 4000h -1 ;

[0047] Reducing gas H2;

[0048] Restoration time: 12 hours;

[0049] The synthesis reaction conditions are: reaction temperature 360℃;

[0050] Reaction pressure: 1.5 MPa;

[0051] Catalyst loading (standard volume hourly space velocity) 4000h -1 ;

[0052] The feedstock ratio (moles) in the synthesis gas is CO / CO2 / H2 = 1:0.15:1;

[0053] The reaction ran for 100 hours.

[0054]

Example 1

[0055] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... 40wt% silica sol of SiO2, 40wt% KOH solution containing 0.04mol K, and 40wt% cobalt sulfate solution containing 0.004mol CoSO4 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25wt% ammonia water, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:3. The material was then calcined at 550°C for 1 hour under a low-oxygen atmosphere with a nitrogen to air volume ratio of 5 to obtain a catalyst. The catalyst composition was: 50wt% Fe... 100 Mn 100 K4Co 0.4 S 0.4 O x +50wt%SiO2.

[0056] XPS analysis showed that the molar ratio of Co to S on the surface of the prepared catalyst was 7.6:1.

[0057] The reaction results of the catalyst evaluation test are shown in Table 1.

[0058]

Example 2

[0059] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... 40 wt% silica sol of SiO2, 40 wt% KOH solution containing 0.04 mol K, and 40 wt% cobalt sulfate solution containing 0.02 mol CoSO4 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25 wt% ammonia water, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:3. The material was then calcined at 550°C for 1 hour under a low-oxygen atmosphere with a nitrogen to air volume ratio of 5 to obtain a catalyst. The catalyst composition was: 50 wt% Fe. 100 Mn 100 K4Co 2.0 S 2.0 O x +50wt%SiO2.

[0060] XPS analysis showed that the molar ratio of Co to S on the surface of the prepared catalyst was 10:1.

[0061] The reaction results of the catalyst evaluation test are shown in Table 1.

[0062]

Example 3

[0063] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... A 40wt% silica sol of SiO2, a 40wt% KOH solution containing 0.04mol K, and a 40wt% cobalt sulfate solution containing 0.0005mol CoSO4 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25wt% ammonia, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:3. The material was then calcined at 550°C for 1 hour in a low-oxygen atmosphere with a nitrogen to air volume ratio of 5 to obtain a catalyst. The catalyst composition was: 50wt% Fe... 100 Mn 100 K4Co 0.05 S 0.05 O x +50wt%SiO2.

[0064] XPS analysis showed that the molar ratio of Co to S on the surface of the prepared catalyst was 5:1.

[0065] The reaction results of the catalyst evaluation test are shown in Table 1.

[0066]

Example 4

[0067] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... A 40wt% silica sol of SiO2, a 40wt% KOH solution containing 0.04 mol K, and a 40wt% cobalt sulfate solution containing 0.004 mol CoSO4 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25wt% ammonia, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:5. The material was then calcined at 550°C for 1 hour in a low-oxygen atmosphere with a nitrogen to air volume ratio of 3 to obtain a catalyst. The catalyst composition was: 50wt% Fe 100 Mn 100 K4Co 0.4 S 0.4 O x +50wt%SiO2.

[0068] XPS analysis showed that the molar ratio of Co to S on the surface of the prepared catalyst was 7.6:1.

[0069] The reaction results of the catalyst evaluation test are shown in Table 1.

[0070]

Example 5

[0071] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... 40wt% silica sol of SiO2, 40wt% NaOH solution containing 0.04mol Na, and 40wt% cobalt sulfate solution containing 0.004mol CoSO4 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25wt% ammonia, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:3. The material was then calcined at 550°C for 1 hour in a low-oxygen atmosphere with a nitrogen to air volume ratio of 5 to obtain a catalyst. The catalyst composition was: 50wt% Fe 100 Mn 100 Na4Co 0.4 S 0.4 O x +50wt%SiO2.

[0072] XPS analysis showed that the molar ratio of Co to S on the surface of the prepared catalyst was 7.6:1.

[0073] The reaction results of the catalyst evaluation test are shown in Table 1.

[0074]

Example 6

[0075] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... A 40wt% silica sol of SiO2, a 40wt% KOH solution containing 0.04 mol K, and a 40wt% cobalt sulfate solution containing 0.004 mol CoSO4 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25wt% ammonia, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:2. The material was then calcined at 550°C for 1 hour under a low-oxygen atmosphere with a nitrogen to air volume ratio of 4 to obtain a catalyst. The catalyst composition was: 50wt% Fe 100 Mn 100 K4Co 0.4 S 0.4 O x +50wt%SiO2.

[0076] XPS analysis showed that the molar ratio of Co to S on the surface of the prepared catalyst was 8.3:1.

[0077] The reaction results of the catalyst evaluation test are shown in Table 1.

[0078]

Comparative Example 1

[0079] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... 40wt% silica sol of SiO2, 40wt% KOH solution containing 0.04mol K, and 40wt% cobalt sulfate solution containing 0.004mol CoSO4 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25wt% ammonia water, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:3. The material was then calcined at 550°C for 1 hour under a low-oxygen atmosphere with a nitrogen to air volume ratio of 5 to obtain a catalyst. The catalyst composition was: 50wt% Fe... 100 Mn 100 K4Co 0.4 S 0.4 O x +50wt%SiO2.

[0080] XPS analysis showed that the molar ratio of Co to S on the surface of the prepared catalyst was 7.6:1.

[0081] The catalyst evaluation conditions were the same as in the example, except that the feedstock ratio (molar) in the evaluation syngas was CO / H2 = 1:2.5. The test reaction results are shown in Table 1.

[0082] [Comparative Example 2]

[0083] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... A 40wt% silica sol of SiO2, a 40wt% KOH solution containing 0.04 mol K, and a 40wt% cobalt nitrate solution containing 0.004 mol Co(NO3)2 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25wt% ammonia, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:3. The material was then calcined at 550°C for 1 hour in a low-oxygen atmosphere with a nitrogen to air volume ratio of 5 to obtain a catalyst. The catalyst composition was: 50wt% Fe 100 Mn 100 K4Co 0.4 O x +50wt%SiO2.

[0084] The reaction results of the catalyst evaluation test are shown in Table 1.

[0085] [Comparative Example 3]

[0086] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... A 40wt% silica sol of SiO2, a 40wt% KOH solution containing 0.04 mol K, and a 40wt% sulfuric acid solution containing 0.004 mol H2SO4 were added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25wt% ammonia water, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was a mixture of air and nitrogen at a volume ratio of 1:3. The material was then calcined at 550°C for 1 hour in a low-oxygen atmosphere with a nitrogen to air volume ratio of 5 to obtain a catalyst. The catalyst composition was: 50wt% Fe. 100 Mn 100 K4S 0.4 O x +50wt%SiO2.

[0087] The reaction results of the catalyst evaluation test are shown in Table 1.

[0088] [Comparative Example 4]

[0089] 1 mol of Fe(NO3)3·9H2O was dissolved in water to prepare a 0.5 mol / L Fe elemental solution. This solution was then mixed with 1350 g of 5 wt% ammonia solution under co-current flow to precipitate and separate. After washing three times with deionized water, fresh Fe(OH)3 precipitate I was obtained. 50 wt% manganese nitrate containing 1 mol of Mn(NO3)2 was diluted with water to prepare a 0.3 mol / L Mn aqueous solution II. The above aqueous solution II, precipitate I, and a certain amount of water were mixed and stirred at 78℃ for a sol-gel reaction for 2 h to obtain a colloidal slurry III with a solid content of 40%. 158 g of... A mixture of 40 wt% SiO2 silica sol, 40 wt% KOH solution containing 0.04 mol K, and 40 wt% cobalt sulfate solution containing 0.004 mol CoSO4 was added to slurry III and stirred at 78°C. Simultaneously, the pH of the mixture was adjusted to 5 with 25 wt% ammonia water, and the solid content of the mixture was adjusted to 35% with water to obtain slurry IV. The slurry was then spray-dried to obtain a spray-dried material. The sprayer inlet temperature was 320°C, the outlet temperature was 190°C, and the hot air medium was pure air. The material was then calcined at 550°C for 1 hour in an air atmosphere to obtain a catalyst. The catalyst composition was: 50 wt% Fe... 100 Mn 100 K4Co 0.4 S 0.4 O x +50wt%SiO2.

[0090] XPS analysis showed that the molar ratio of Co to S on the surface of the prepared catalyst was 2:1.

[0091] The reaction results of the catalyst evaluation test are shown in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] The specific 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 combining the 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. A catalyst for the direct production of olefins from synthesis gas, characterized in that, The catalyst comprises 20-50 parts by weight of the carrier and 50-80 parts by weight of the active component; The active component comprises a composition of the formula Fe 100 Mn a B b Co c S c O x ; wherein B comprises at least one selected from alkali metals, a is in the range of 3-150; b is in the range of 0.1-10; c is in the range of 0.05-2; x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst; the molar ratio of Co to S on the surface of the catalyst is 5-10:

1.

2. The catalyst of claim 1, wherein The carrier comprises at least one of the oxides of Si and Al. And / or, B comprises at least one of Na, K, Rb, and Cs.

3. A method for preparing the catalyst of any one of claims 1-2, comprising the following steps: (1) obtaining precipitate I by co-currently mixing a soluble Fe salt with a precipitant; (2) mixing precipitate I, a Mn salt, a carrier, a source of alkali metal, and CoSO4 to obtain slurry II; (3) spray-drying and shaping slurry II of step (2) and calcining to obtain the catalyst.

4. The preparation method according to claim 3, characterized in that, The soluble Fe salt in step (1) comprises at least one of ferric nitrate, ferrous nitrate, ferric chloride, ferrous chloride, ferric citrate, ferrous citrate, ferric acetate, and ferrous acetate. And / or, the precipitant in step (1) comprises at least one of ammonia, potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide.

5. The preparation method according to claim 3, characterized in that, The Mn salt in step (2) comprises at least one of manganese nitrate, manganese acetate, and manganese citrate. And / or, the source of alkali metal in step (2) comprises at least one of an alkali metal-containing base and salt.

6. The preparation method according to claim 3, characterized in that, An acid-base regulator is added in step (2) to adjust the pH of slurry II to 1-5. And / or, the solid content of the slurry obtained in step (2) is 15-45% by weight.

7. The preparation method according to claim 3, characterized in that, The calcination temperature in step (3) is 450-700°C; the calcination time is 0.3-5 h; and the calcination atmosphere is a mixture of nitrogen and air. And / or, the hot air temperature for spray-drying in step (3) is 150-350°C.

8. The preparation method according to claim 7, characterized in that, In the calcination atmosphere in step (3), the volume ratio of nitrogen to air is 2-5:

1. And / or, the hot air medium for spray-drying in step (3) is a mixture of air and a non-oxygen gas.

9. The preparation method according to claim 8, characterized in that, In the hot air medium for spray-drying in step (3), the volume ratio of air to non-oxygen gas is 1:2-5.

10. The preparation method according to claim 8, characterized in that, In the hot air medium for spray-drying in step (3), the non-oxygen gas is nitrogen.

11. Use of the catalyst of any one of claims 1-2 or the catalyst prepared by the method of any one of claims 3-10 in a reaction for directly preparing olefins from synthesis gas.

12. Use according to claim 11, characterized in that, The composition of the synthesis gas comprises CO, CO2, and hydrogen.

13. Use according to claim 12, characterized in that, In the synthesis gas, the volume ratio of CO, CO2, and hydrogen is 1:0.1-0.3:0.6-1.8.

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