Catalyst for preparing low-carbon olefin from Fischer-Tropsch synthesis light oil and crude oil as well as preparation and application of catalyst

Abstract

The invention discloses a catalyst for preparing low-carbon olefin by Fischer-Tropsch synthesis of light oil and crude oil as well as preparation and application of the catalyst. The catalyst comprises the following components in parts by mass: 0.1-30 parts of a metal active component; 30-80 parts of a molecular sieve; 30 to 60 parts of a binder; 0.1-5 parts of an alkali metal auxiliary agent; the metal active component is one or more of Mo, Mn, Ce and Ni. The preparation method of the catalyst is simple and easy to implement, and the yield of ethylene and propylene prepared by catalytic cracking of Fischer-Tropsch synthesis light oil and crude oil is high.

Description

Technical Field

[0001] The invention relates to a catalyst for preparing low-carbon olefins from Fischer-Tropsch synthesis of light oil and crude oil, and the preparation and application of the catalyst. Background Art

[0002] At present, refined oil has shown a trend of oversupply. At the same time, with the development of chemical technology, low-carbon olefins are more widely used in industry, and their production growth rate is obvious, but it still cannot meet their consumption. The above reasons have prompted refining companies to transform from fuel-type products to chemical products. Direct cracking of crude oil is a new research hotspot. By directly cracking crude oil to obtain low-carbon olefins, the intermediate refining link is omitted, and energy and hydrogen consumption are saved. However, due to the large number of heavy components in crude oil, the conversion rate of direct cracking is low, and the yield of low-carbon olefins is not high.

[0003] In recent years, the industrialization of coal-to-liquid technology has developed steadily. Coal generates hydrocarbon compounds through the Fischer-Tropsch synthesis reaction, which can be divided into low-temperature Fischer-Tropsch synthesis and high-temperature Fischer-Tropsch synthesis according to the reaction temperature. The light oil part of the Fischer-Tropsch synthesis product has the advantages of low fraction density, high alkane and olefin content, low aromatic content, and low sulfur and nitrogen content. It is a high-quality raw material for cracking low-carbon olefins. Summary of the invention

[0004] The present invention is made in order to at least partially achieve the goal of increasing the conversion rate and light olefin yield of crude oil and Fischer-Tropsch synthetic light oil.

[0005] As a first aspect of the present invention, it relates to a catalyst for preparing light olefins from Fischer-Tropsch synthesis of light oil and crude oil, the catalyst comprising the following components by mass:

[0006] 0.1-30 parts of metal active component;

[0007] Molecular sieve 30-80 parts;

[0008] 30-60 parts of binder;

[0009] Alkali metal additive 0.1-5 parts;

[0010] The metal active component is one or more of Mo, Mn, Ce and Ni.

[0011] In one or some optional embodiments, the molecular sieve is one or both of SAPO-34 molecular sieve and ZSM-5 molecular sieve.

[0012] In one or some optional embodiments, the binder is pseudo-boehmite.

[0013] In one or some optional embodiments, the alkali metal additive comprises one or more of Mg, Ca, K and Na.

[0014] As a second aspect of the present invention, it relates to a method for preparing the above catalyst, the method comprising:

[0015] After adding the binder into water and stirring evenly, nitric acid is added to form gel, and then nitrates or oxides containing metal active components are added in sequence to perform temperature-variable aging, and then alkali metal additives and molecular sieves are added and mixed evenly, and the catalyst is obtained after drying and calcining.

[0016] In one or some optional embodiments, the variable temperature aging is divided into at least two stages, the at least two stages are the first stage and the second stage; the aging temperature of the first stage is 40-70°C, and the aging temperature of the second stage is 1-10°C.

[0017] In one or some preferred embodiments, the first aging temperature is 40-60°C, and the second aging temperature is 2-8°C.

[0018] As a third aspect of the present invention, it relates to a method for using the above catalyst in the Fischer-Tropsch synthesis of light oil and crude oil to produce low-carbon olefins, comprising:

[0019] S1 Fischer-Tropsch synthetic light oil enters the bottom of the riser reactor and contacts the catalyst at the bottom for cracking reaction. The catalyst after reaction and the oil and gas produced by cracking of Fischer-Tropsch synthetic light oil move to the middle of the riser reactor;

[0020] S2 crude oil enters the middle of the riser reactor, meets the catalyst after reaction and the oil and gas produced by cracking of Fischer-Tropsch synthesis light oil, and reacts. The reaction products and the deactivated catalyst continue to move upward and flow out from the outlet of the riser reactor.

[0021] S3 separates the reaction product from the deactivated catalyst to obtain light olefins;

[0022] In one or some optional embodiments, the reaction conditions in S1 are: reaction temperature 650-800° C., residence time 0.5-3 s, agent-oil ratio 5-50.

[0023] In one or some optional embodiments, the reaction conditions in S2 are: reaction temperature 600-750° C., residence time 1-4 s, agent-oil ratio 10-60.

[0024] In one or some optional embodiments, the catalyst regeneration temperature in S3 is 700-800°C.

[0025] In one or some preferred embodiments, the catalyst regeneration temperature in S3 is 720-800°C.

[0026] In one or some optional embodiments, the application method further comprises:

[0027] S4 regenerates the separated deactivated catalyst through a regeneration reactor, and the regenerated catalyst is returned to the bottom of the riser reactor for recycling.

[0028] The present invention introduces metal oxide active components and alkali metal additives during the preparation of the molecular sieve catalyst to adjust the acid center of the catalyst so that the catalyst has both suitable acid centers and cracking performance. In addition, the preparation method of the catalyst provided by the present invention is simple and easy, and the catalyst provided by the present invention is used for the Fischer-Tropsch synthesis of light oil and crude oil catalytic cracking to produce ethylene and propylene with a high yield.

[0029] According to the present invention, Fischer-Tropsch synthesis light oil and crude oil enter into a riser reactor at different positions to participate in catalytic cracking reaction, and the Fischer-Tropsch synthesis light oil is preferentially contacted with the catalyst for reaction, which is beneficial to the catalytic cracking of the Fischer-Tropsch synthesis light oil at high temperature to generate a large amount of low-carbon olefins. At the same time, since the carbon residue of the Fischer-Tropsch synthesis light oil is zero, the carbon deposition on the catalyst after the reaction is less, and the influence on the activity of the catalyst is less. After the crude oil is fed into the middle part of the riser reactor, due to the high content of heavy components in the crude oil, it is easier to adsorb on the catalyst, thereby blocking the further cracking of the Fischer-Tropsch synthesis light oil, reducing the generation of low value-added products such as hydrogen and methane, and improving the yield and selectivity of low-carbon olefins. At the same time, the catalyst contacts with the crude oil in the oil and gas, thereby improving the conversion rate of the crude oil, reducing the coke yield in the crude oil cracking process, and reducing energy consumption. DETAILED DESCRIPTION

[0030] The following is a detailed description of the embodiments of the present invention: The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments. The process parameters for which specific conditions are not specified in the following embodiments are generally based on conventional conditions.

[0031] The endpoints and any values ​​of the ranges disclosed in the present invention 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0032] The inventor refers to patent CN113710776A and uses a combination of thermal hydrotreatment, hydrotreatment and steam cracking to convert the heavy fraction or full fraction of crude oil into ethylene, propylene, butene and benzene under a high severity. However, the process of this method is cumbersome, the process is complicated, and the hydrogen consumption and energy consumption are large. The inventor refers to patent CN105567299A, a method for preparing light olefins by Fischer-Tropsch synthesis cracking, using 10-25wt% of heavy fraction oil and 75-90wt% of Fischer-Tropsch synthesis oil as cracking raw materials, and the heavy fraction oil and Fischer-Tropsch synthesis oil are successively contacted with a catalytic cracking catalyst for reaction. Adding heavy fractions to Fischer-Tropsch synthesis oil can not only promote the generation of light olefins, but also meet the heat demand of the regeneration system. The catalysts used in this experiment include zeolite, oxides and clay. However, the maximum yield of ethylene and propylene obtained by this method is only 43.39wt%. The inventor refers to patent CN105567307A, a method for producing low-carbon olefins from Fischer-Tropsch oil alone, first contacting Fischer-Tropsch oil with amorphous alumina and / or amorphous alumina carrier for thermal cracking, and the reaction product contacts the catalyst for catalytic cracking reaction. During the thermal cracking process, the olefin content in the Fischer-Tropsch oil increases, and a portion of oxygen is removed. This method can improve the yield of low-carbon olefins on the one hand, and reduce the content of oxygen-containing compounds in the cracked gas on the one hand. The catalyst used is a zeolite containing ultra-stable zeolite and an average pore size of less than 0.7 nanometers. However, the triene yield of this method is only 49.45wt% at most. The inventor refers to patent CN110028987A, a method for hydrofining of Fischer-Tropsch oil, pre-hydrogenating the Fischer-Tropsch oil at low temperature, performing deep hydrodeoxygenation reaction on the pre-hydrogenated product, and obtaining a hydrofining product, and a portion of the hydrofining product returns to the low-temperature pre-hydrogenation link. This method uses platinum or palladium catalysts in the low-temperature pre-hydrogenation process, and uses a high-nickel catalyst with a nickel content of 30-45wt% in the deep hydrogenation reaction. The metal content in the catalyst is relatively high, and the economic efficiency is not strong.

[0033] In view of the fact that the above solutions failed to meet the inventor's expectations, the inventor made the present invention after further research.

[0034] Example 1

[0035] Catalysts for preparing high-yield low-carbon olefins:

[0036] Add 13kg pseudo-boehmite (mass fraction 65%) to 200kg water, stir well, then add nitric acid to form gel, add 0.4kg magnesium oxide, 2kg nickel nitrate, stir at room temperature for 1h, then heat to 60℃ for aging for 4h, then cool to 2℃ for 5h. Add 1.2kg manganese oxide to the pseudo-boehmite gel, and finally add 10kg ZSM-5 molecular sieve and appropriate amount of water, mix well and spray dry to obtain catalyst pellets. Soak the catalyst pellets with a mixed solution of 0.1kg potassium hydroxide and 10kg water at room temperature for 5h, then wash and filter, and calcine at 600℃ for 5h to obtain a molded catalyst. The components in the catalyst are calculated based on the oxide mass ratio, alumina: ZSM-5 molecular sieve: metal oxide: alkali metal additive = 40.9: 48.4: 8.3: 2.3, wherein the mass of the metal oxide is the sum of a mixture of nickel oxide and manganese oxide formed by roasting the raw material nickel nitrate, and the mass of the alkali metal additive is the sum of potassium oxide and magnesium oxide formed by roasting the raw material potassium hydroxide.

[0037] Using 50% crude oil and 50% Fischer-Tropsch synthetic light oil as raw materials to produce low-carbon olefins:

[0038] S1 Fischer-Tropsch synthetic light oil enters the bottom of the riser reactor and contacts the catalyst at the bottom for cracking reaction. The catalyst after the reaction and the oil and gas produced by the cracking of the Fischer-Tropsch synthetic light oil move to the middle of the riser reactor; the reaction temperature is 750℃, the average residence time is controlled at 3s, and the catalyst-oil ratio is 30.

[0039] S2 crude oil enters the middle of the riser reactor, meets the reacted catalyst and the oil and gas produced by the cracking of Fischer-Tropsch light oil, and reacts. The reaction products and the deactivated catalyst continue to move upward and flow out from the outlet of the riser reactor; the reaction temperature is 700℃, the average residence time is controlled at 1.5s, and the catalyst-oil ratio is 30.

[0040] The product after the S3 reaction and the deactivated catalyst enter the separation system for separation to obtain light olefins.

[0041] The deactivated catalyst after S4 separation is treated by the stripping unit and then enters the regeneration reactor for regeneration. The regeneration temperature is controlled at about 750°C, and the regenerated catalyst is returned to the bottom of the riser reactor for recycling.

[0042] In this example, based on the total feed, the ethylene and propylene yield is 51.2 wt%.

[0043] The properties of the crude oil used in this example are shown in Table 1 for the Daqing crude oil.

[0044] Table 1 Crude oil properties

[0045]

[0046]

[0047] The physical properties of the Fischer-Tropsch synthetic light oil used in this example are shown in Table 2.

[0048] Table 2 Physical properties of Fischer-Tropsch synthetic light oil

[0049]

[0050] The composition of the Fischer-Tropsch light oil of this embodiment is shown in Table 3.

[0051] Table 3 Composition of Fischer-Tropsch light oil

[0052]

[0053] Example 2

[0054] Catalysts for preparing high-yield low-carbon olefins:

[0055] Add 9.2kg of pseudo-boehmite (mass fraction of 65%) to 180kg of water, stir well, then add nitric acid to form a gel, then add 0.2kg of magnesium oxide and 2kg of nickel nitrate, stir at room temperature for 1h, then heat to 40℃ for aging for 4h, then cool to 4℃ for 5h. Add 3kg of cobalt nitrate and 1.05kg of cerium nitrate to the gel of pseudo-boehmite, and finally add 11.95kg of ZSM-5 molecular sieve and appropriate amount of water, mix well and spray dry to obtain catalyst pellets. Soak the catalyst pellets with a mixed solution of 0.1kg of sodium hydroxide and 10kg of water at room temperature for 5h, then wash and filter, and calcine at 600℃ for 5h to obtain a molded catalyst. The components in the catalyst are calculated based on the oxide mass ratio, alumina: ZSM-5 molecular sieve: metal oxide: alkali metal additive = 30:60:8.5:1.4, wherein the mass of the metal oxide is the sum of a mixture of nickel oxide, cobalt oxide and cerium oxide formed by roasting raw materials nickel nitrate, cobalt nitrate and cerium nitrate, and the mass of the alkali metal additive is the sum of a mixture of sodium oxide formed by roasting raw material sodium hydroxide and raw material magnesium oxide.

[0056] Production of light olefins:

[0057] The same as Example 1, except that this example uses 30% of Zhongyuan crude oil and 70% of Fischer-Tropsch synthetic light oil as raw materials, the contact temperature of the Fischer-Tropsch synthetic light oil and the catalyst is 700°C, the catalyst-oil ratio is 40, the residence time is 2s, the reaction temperature at the outlet of the riser reactor is 650°C, the catalyst-oil ratio is 30, and the residence time is 2s; based on the total feed, the ethylene propylene yield reaches 50.78wt%.

[0058] Example 3

[0059] Catalysts for preparing high-yield low-carbon olefins:

[0060] Add 14kg of pseudo-boehmite (65% by mass) to 180kg of water, stir well, add nitric acid to form a gel, then add 2kg of calcium nitrate and 5kg of cobalt nitrate and stir at room temperature for 1h, then heat to 60℃ for aging for 4h, then cool to 6℃ for 5h. Add 5kg of cerium nitrate to the gel of pseudo-boehmite, and finally add 17kg of ZSM-5 molecular sieve and appropriate amount of water, mix well and spray dry to obtain catalyst pellets. Soak the catalyst pellets with a mixed solution of 0.2kg potassium hydroxide and 10kg water at room temperature for 5h, then wash and filter, and calcine at 600℃ for 5h to obtain a molded catalyst. The components in the catalyst are calculated based on the oxide mass ratio, alumina: ZSM-5 molecular sieve: metal oxide: alkali metal additive = 30.1: 56.3: 10.8: 2.8, wherein the mass of the metal oxide is the sum of a mixture of cobalt oxide and cerium oxide formed by roasting raw materials cobalt nitrate and cerium nitrate, and the mass of the alkali metal additive is the sum of calcium oxide and potassium oxide formed by roasting raw materials calcium nitrate and potassium hydroxide.

[0061] Production of light olefins:

[0062] The same as Example 1, except that this example uses 10% crude oil and 90% Fischer-Tropsch light oil as raw materials, the contact temperature of the Fischer-Tropsch light oil and the catalyst is 700°C, the catalyst-oil ratio is 45, the residence time is 1.1s, the reaction temperature at the outlet of the riser reactor is 650°C, the catalyst-oil ratio is 30, and the residence time is 1.2s; based on the total feed, the ethylene propylene yield reaches 49.78wt%.

[0063] Example 4

[0064] Catalysts for preparing high-yield low-carbon olefins:

[0065] Add 14kg of pseudo-boehmite (mass fraction of 65%) to 180kg of water, stir well, then add nitric acid to form a gel, then add 0.05kg of calcium oxide, 0.2kg of magnesium nitrate and 2kg of nickel oxide, stir at room temperature for 1h, then heat to 50℃ for aging for 4h, then cool to 8℃ for 5h. Add 5kg of cobalt nitrate and 4kg of cerium nitrate to the gel of pseudo-boehmite, and finally add 11.95kg of ZSM-5 molecular sieve and appropriate amount of water, mix well and spray dry to obtain catalyst pellets. Soak the catalyst pellets in a mixed solution of 0.1kg of sodium oxide and 30kg of water at room temperature for 5h, then wash and filter, and calcine at 600℃ for 5h to obtain a molded catalyst. The components in the catalyst are calculated based on the oxide mass ratio, alumina: ZSM-5 molecular sieve: metal oxide: alkali metal additive = 34.8: 45.7: 18.6: 0.8, wherein the mass of the metal oxide is the sum of a mixture of cobalt oxide and cerium oxide formed by calcining raw materials cobalt nitrate and cerium nitrate, and raw material nickel oxide, and the mass of the alkali metal additive is the sum of magnesium oxide and sodium oxide formed by calcining raw materials magnesium nitrate and sodium hydroxide, and raw material calcium oxide.

[0066] Production of light olefins:

[0067] The same as Example 1, except that 50% crude oil and 50% Fischer-Tropsch light oil are used as raw materials, the contact temperature of Fischer-Tropsch light oil and catalyst is 750°C, the catalyst-oil ratio is 45, the residence time is 1.2s, the reaction temperature at the outlet of the riser reactor is 700°C, the catalyst-oil ratio is 55, and the residence time is 1.3s; based on the total feed, the ethylene propylene yield reaches 49.84wt%.

[0068] Example 5

[0069] Catalysts for preparing high-yield low-carbon olefins:

[0070] Add 12kg pseudo-boehmite (mass fraction 65%) to 180kg water, stir well, add nitric acid to form gel, then add 0.05kg manganese oxide, 0.2kg magnesium nitrate and 1kg nickel oxide, stir at room temperature for 1h, then heat to 40℃ for aging for 4h, then cool to 5℃ for 5h. Add 2kg cobalt oxide and 1kg cerium oxide to the gel of pseudo-boehmite, and finally add 5.975kg ZSM-5 molecular sieve and 5.975kg SAPO-34 molecular sieve and appropriate amount of water, mix well and spray dry to obtain catalyst pellets. Soak the catalyst pellets with a mixed solution of 0.05kg sodium oxide and 30kg water at room temperature for 5h, then wash and filter, and calcine at 600℃ for 5h to obtain a molded catalyst. The components in the catalyst are calculated based on the oxide mass ratio, alumina: ZSM-5 molecular sieve: SAPO-34 molecular sieve: metal oxide: alkali metal additive = 32.6: 24.95: 24.95: 16.9: 0.6, wherein the mass of the metal oxide is the sum of the masses of the mixture of raw materials manganese oxide, nickel oxide, cobalt oxide and cerium oxide, and the mass of the alkali metal additive is the sum of the masses of magnesium oxide and sodium oxide formed by roasting the raw materials magnesium nitrate and sodium hydroxide.

[0071] Production of light olefins:

[0072] The same as Example 1, except that 30% of Zhongyuan crude oil and 70% of Fischer-Tropsch synthetic light oil are used as raw materials, the contact temperature of Fischer-Tropsch synthetic light oil and catalyst is 650°C, the catalyst-oil ratio is 5, the residence time is 3s, the reaction temperature at the outlet of the riser reactor is 600°C, the catalyst-oil ratio is 10, and the residence time is 3s; based on the total feed, the ethylene propylene yield reaches 45.98wt%.

[0073] Example 6

[0074] Catalysts for preparing high-yield low-carbon olefins:

[0075] Add 14kg of pseudo-boehmite (65% by mass) to 180kg of water, stir well, add nitric acid to form a gel, then add 2kg of calcium nitrate and 5kg of cobalt nitrate and stir at room temperature for 1h, then heat to 60℃ for aging for 4h, then cool to 3℃ for 5h. Add 5kg of cerium nitrate to the gel of pseudo-boehmite, and finally add 17kg of ZSM-5 molecular sieve and appropriate amount of water, mix well and spray dry to obtain catalyst pellets. Soak the catalyst pellets with a mixed solution of 0.2kg potassium hydroxide and 10kg water at room temperature for 5h, then wash and filter, and calcine at 600℃ for 5h to obtain a molded catalyst. The components in the catalyst are calculated based on the oxide mass ratio, alumina: ZSM-5 molecular sieve: metal oxide: alkali metal additive = 30.1: 56.3: 10.8: 2.8, wherein the mass of the metal oxide is the sum of the masses of a mixture of cobalt oxide and cerium oxide formed by roasting raw materials cobalt nitrate and cerium nitrate, and the mass of the alkali metal additive is the sum of the masses of calcium oxide and potassium oxide formed by roasting raw materials calcium nitrate and potassium hydroxide.

[0076] Production of light olefins:

[0077] The same as Example 1, except that 10% crude oil and 90% Fischer-Tropsch light oil are used as raw materials, the contact temperature of Fischer-Tropsch light oil and catalyst is 800°C, the catalyst-oil ratio is 50, the residence time is 2s, the reaction temperature at the outlet of the riser reactor is 750°C, the catalyst-oil ratio is 60, and the residence time is 3s; based on the total feed, the ethylene propylene yield reaches 55.84wt%.

[0078] Comparative Example 1

[0079] Add 12kg of pseudo-boehmite (mass fraction of 65%) to 180kg of water, stir well, then add nitric acid to form a gel, then add 1.2kg of manganese oxide and 5kg of cobalt nitrate, stir at room temperature for 1h, then heat to 60℃ for aging for 4h, then cool to 2℃ for 5h. Add 5kg of cerium nitrate and 2kg of nickel nitrate to the gel of pseudo-boehmite, and finally add 16kg of ZSM-5 molecular sieve and appropriate amount of water, mix well and spray dry to obtain catalyst pellets. Soak the catalyst pellets with a mixed solution of 0.1kg potassium hydroxide and 10kg water at room temperature for 5h, then wash and filter, and calcine at 600℃ for 5h to obtain a molded catalyst. The components in the catalyst are calculated based on the oxide mass ratio, alumina: ZSM-5 molecular sieve: metal oxide: alkali metal additive = 27.1: 55.4: 17.3: 0.3, wherein the mass of the metal oxide is the sum of the masses of cobalt oxide, cerium oxide and nickel oxide formed by roasting the raw materials cobalt nitrate, cerium nitrate and nickel nitrate, and the raw material manganese oxide mixture, and the mass of the alkali metal additive is the mass of potassium oxide formed by roasting the raw material potassium hydroxide.

[0080] With 50% crude oil and 50% Fischer-Tropsch light oil as raw materials, the ethylene and propylene yield is 41.19 wt % based on the total feed.

[0081] Comparative Example 2

[0082] Add 35kg of pseudo-boehmite (mass fraction of 65%) to 180kg of water, stir well, then add nitric acid to form a gel, then add 3kg of nickel nitrate and stir at room temperature for 1h, then heat to 60℃ and age for 4h, then cool to 2℃ and cool for 5h. Add 6kg of cobalt nitrate and 7kg of cerium nitrate to the gel of pseudo-boehmite, and finally add 30kg of ZSM-5 molecular sieve and appropriate amount of water, mix well and spray dry to obtain catalyst pellets. Soak the catalyst pellets with a mixed solution of 0.05kg of potassium hydroxide and 30kg of water at room temperature for 5h, then wash and filter, and calcine at 600℃ for 5h to obtain a molded catalyst. The components in the catalyst are calculated based on the oxide mass ratio, alumina: ZSM-5 molecular sieve: metal oxide: alkali metal additive = 39.3: 51.8: 8.8: 0.07, wherein the mass of the metal oxide is the sum of the masses of a mixture of cobalt oxide, nickel oxide and cerium oxide formed by roasting raw materials cobalt nitrate, nickel nitrate and cerium nitrate, and the mass of the alkali metal additive is the mass of potassium oxide formed by roasting raw material potassium hydroxide.

[0083] With 30% of Zhongyuan crude oil and 70% of Fischer-Tropsch light oil as raw materials, the yield of ethylene and propylene is 42.99wt% based on the total feed.

[0084] A comparative analysis of the reaction results of Examples 1 to 6 and Comparative Examples 1 to 2 shows that: the catalyst prepared in Comparative Example 1 has too low alumina content, fewer acid centers with larger pore sizes, low raw material conversion rate, and low ethylene + propylene yield; the catalyst prepared in Comparative Example 2 has a low proportion of alkaline metals, resulting in stronger acid centers, excessive hydrogen transfer reactions, and low olefin yields; the catalysts prepared in Examples 1 to 6 have appropriate contents of each component and have higher ethylene and propylene yields.

[0085] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art. According to all the teachings disclosed, various modifications and replacements can be made to those details, and these changes are all within the protection scope of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. A catalyst for preparing low-carbon olefins from Fischer-Tropsch synthesis of light oil and crude oil, characterized in that: The catalyst comprises the following components by mass: 0.1-30 parts of metal active component; Molecular sieve 30-80 parts; 30-60 parts of binder; Alkali metal additive 0.1-5 parts; The metal active component is one or more of Mo, Mn, Ce and Ni.

2. The catalyst according to claim 1, characterized in that The molecular sieve is one or both of SAPO-34 molecular sieve and ZSM-5 molecular sieve.

3. The catalyst according to claim 1, characterized in that The binder is pseudo-boehmite.

4. The catalyst according to claim 1, characterized in that The alkali metal additive includes one or more of Mg, Ca, K and Na.

5. A method for preparing the catalyst according to any one of claims 1 to 4, characterized in that: include: After adding the binder into water and stirring evenly, nitric acid is added to form gel, and then nitrates or oxides containing metal active components are added in sequence to perform temperature-variable aging, and then alkali metal additives and molecular sieves are added and mixed evenly, and the catalyst is obtained after drying and calcining.

6. The method according to claim 5, characterized in that The variable temperature aging is divided into at least two stages, which are the first stage and the second stage; the aging temperature of the first stage is 40-70°C, and the aging temperature of the second stage is 1-10°C.

7. The method according to claim 6, characterized in that The aging temperature in the first stage is 40-60°C, and the aging temperature in the second stage is 2-8°C.

8. The method for using the catalyst according to any one of claims 1 to 4 in the preparation of light olefins from Fischer-Tropsch synthesis of light oil and crude oil, characterized in that: include: S1 Fischer-Tropsch synthetic light oil enters the bottom of the riser reactor and contacts the catalyst at the bottom for cracking reaction. The catalyst after reaction and the oil and gas produced by cracking of Fischer-Tropsch synthetic light oil move to the middle of the riser reactor; S2 crude oil enters the middle of the riser reactor, meets the catalyst after reaction and the oil and gas produced by cracking of Fischer-Tropsch synthesis light oil, and reacts. The reaction products and the deactivated catalyst continue to move upward and flow out from the outlet of the riser reactor. S3 separates the reaction product from the deactivated catalyst to obtain light olefins.

9. The application method according to claim 8, characterized in that: The reaction conditions in S1 are: reaction temperature 650-800° C., residence time 0.5-3 s, agent-oil ratio 5-50.

10. The application method according to claim 8, characterized in that: The reaction conditions in S2 are: reaction temperature 600-750° C., residence time 1-4 s, agent-oil ratio 10-60.

11. The application method according to claim 8, characterized in that: The catalyst regeneration temperature in S3 is 700-800°C.

12. The application method according to claim 11, characterized in that: The catalyst regeneration temperature in S3 is 720-800°C.

13. The application method according to claim 8, characterized in that: Also includes: The deactivated catalyst separated by S4 is regenerated by the regeneration reactor, and the regenerated catalyst is returned to the bottom of the riser reactor for recycling.

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