A catalyst for preparing low-carbon olefins from fischer-tropsch light oil and crude oil, and preparation and application thereof

Abstract

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

Description

Technical Field

[0001] This invention relates to a catalyst for the synthesis of low-carbon olefins from light oil and crude oil in the Fischer-Tropsch synthesis, as well as its preparation and application. Background Technology

[0002] Currently, refined oil products are showing signs of oversupply. Meanwhile, with the development of chemical technology, low-carbon olefins are being used more widely in industry, and their production growth rate is significant, but it still cannot meet consumption. These factors are prompting refining and chemical enterprises to shift from fuel-based products to chemical-based products, making direct crude oil cracking a new research hotspot. Directly cracking crude oil to obtain low-carbon olefins eliminates intermediate refining steps, saving energy and hydrogen consumption. However, due to the high content of heavy components in crude oil, the conversion rate of direct cracking is low, resulting in a low yield of low-carbon olefins.

[0003] In recent years, the industrialization of coal-to-oil technology has developed steadily. Coal undergoes Fischer-Tropsch synthesis to produce hydrocarbon compounds, which can be divided into low-temperature Fischer-Tropsch synthesis and high-temperature Fischer-Tropsch synthesis according to the reaction temperature. The light oil fraction of Fischer-Tropsch synthesis products has advantages such as low distillation density, high alkane and olefin content, low aromatic content, and low sulfur and nitrogen content, making it a high-quality feedstock for cracking to produce low-carbon olefins. Summary of the Invention

[0004] This invention was made in order to at least partially improve the conversion rates of crude oil and Fischer-Tropsch light oil and the yield of low-carbon olefins.

[0005] As a first aspect of the invention, there is a catalyst for the synthesis of low-carbon olefins from light oil and crude oil in the Fischer-Tropsch synthesis, the catalyst comprising the following components in parts by mass:

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

[0007] 30-80 parts of molecular sieve;

[0008] 30-60 parts adhesive;

[0009] Alkali metal auxiliaries: 0.1-5 parts;

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

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

[0012] In one or more alternative embodiments, the binder is boehmite.

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

[0014] As a second aspect of the present invention, a method for preparing the above-mentioned catalyst is provided, the method comprising:

[0015] After the binder is added to water and stirred evenly, nitric acid is added to form a gel. Then, nitrates or oxides containing metal active components are added in sequence for temperature-variable aging. Finally, alkali metal additives and molecular sieves are added and mixed evenly. After drying and calcination, the catalyst is obtained.

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

[0017] In one or more 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, a method for using the above-mentioned catalyst in the production of low-carbon olefins from Fischer-Tropsch light oil and crude oil is provided, comprising:

[0019] S1 Fischer-Tropsch light oil enters at the bottom of the riser reactor and comes into contact with the catalyst at the bottom for cracking reaction. The catalyst and the oil and gas generated by the cracking of Fischer-Tropsch light oil move to the middle of the riser reactor.

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

[0021] S3 separates the reaction products from the deactivated catalyst to obtain low-carbon olefins;

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

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

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

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

[0026] In one or more optional embodiments, the application method further includes:

[0027] S4 regenerates the deactivated catalyst after separation in the regeneration reactor, and the regenerated catalyst is returned to the bottom of the riser reactor for recycling.

[0028] This invention modulates the acidity of molecular sieve catalysts by introducing metal oxide active components and alkali metal promoters during the catalyst preparation process, thereby enabling the catalyst to simultaneously possess suitable acidity and cracking performance. Furthermore, the catalyst preparation method provided by this invention is simple and easy to implement, and the catalyst provides high yields for the catalytic cracking of Fischer-Tropsch light oil and crude oil to produce ethylene and propylene.

[0029] This invention introduces Fischer-Tropsch light oil and crude oil into a riser reactor at different locations to participate in the catalytic cracking reaction. The preferential contact between the Fischer-Tropsch light oil and the catalyst promotes the high-temperature catalytic cracking of the light oil to generate a large amount of low-carbon olefins. Simultaneously, since the Fischer-Tropsch light oil has zero residual carbon, there is less carbon buildup on the catalyst after the reaction, minimizing its impact on catalyst activity. Crude oil, fed into the middle of the riser reactor, has a higher content of heavy components, making it easier to adsorb onto the catalyst, thus preventing further cracking of the Fischer-Tropsch 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. Furthermore, the contact between the catalyst and crude oil in the oil and gas process increases the conversion rate of crude oil, reduces the coke yield during crude oil cracking, and decreases energy consumption. Detailed Implementation

[0030] The embodiments of the present invention are described in detail below: The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0031] The endpoints and any values ​​of the ranges disclosed in this 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 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 in this invention.

[0032] The inventors, referring to patent CN113710776A, described a method for converting heavy or whole crude oil fractions into ethylene, propylene, butene, and benzene under high-critical conditions using a combination of thermal hydrotreating, hydrotreating, and steam cracking. However, this method is cumbersome, complex, and consumes significant amounts of hydrogen and energy. The inventors also referenced patent CN105567299A, a method for producing low-carbon olefins through Fischer-Tropsch synthesis cracking. This method uses a mixture of 10-25 wt% heavy distillate oil and 75-90 wt% Fischer-Tropsch synthesis oil as the cracking feedstock. The heavy distillate oil and Fischer-Tropsch synthesis oil are then reacted sequentially with a catalytic cracking catalyst. Adding heavy distillate to the Fischer-Tropsch synthesis oil not only promotes the formation of low-carbon olefins but also meets the heat requirements of the regeneration system. The catalysts used in this experiment included zeolites, oxides, and clay. However, the highest ethylene and propylene yield obtained by this method was only 43.39 wt%. The inventors, referring to patent CN105567307A, described a method for producing low-carbon olefins solely from Fischer-Tropsch synthetic oil. This method involves first thermally cracking the Fischer-Tropsch synthetic oil with amorphous alumina and / or an amorphous alumina support, followed by catalytic cracking of the reaction products with a catalyst. During thermal cracking, the olefin content in the Fischer-Tropsch synthetic oil increases, and some oxygen is removed. This method can improve the yield of low-carbon olefins while reducing the content of oxygenated compounds in the cracked gas. The catalyst used is a zeolite containing ultrastable zeolite and an average pore size of less than 0.7 nanometers. However, the highest yield of trienes using this method is only 49.45 wt%. The inventors, also referring to patent CN110028987A, described a method for hydrorefining Fischer-Tropsch synthetic oil. This method involves low-temperature pre-hydrogenation of the Fischer-Tropsch synthetic oil, followed by deep hydrodeoxygenation of the pre-hydrogenated product to obtain a hydrorefined product, with a portion of the hydrorefined product returned to the low-temperature pre-hydrogenation stage. This method uses platinum or palladium catalysts in the low-temperature pre-hydrogenation process and high-nickel catalysts with a nickel content of 30-45 wt% in the deep hydrogenation reaction. The high metal content in the catalysts makes it uneconomical.

[0033] Since none of the above met the inventor's expectations, the inventor conducted further research and came up with this invention.

[0034] Example 1

[0035] Catalysts for producing high yields of low-carbon olefins:

[0036] 13 kg of boehmite (65% by mass) was added to 200 kg of water and stirred until homogeneous. Nitric acid was then added to form a gel. 0.4 kg of magnesium oxide and 2 kg of nickel nitrate were added and stirred at room temperature for 1 hour. The mixture was then heated to 60°C and aged for 4 hours, followed by cooling to 2°C for 5 hours. 1.2 kg of manganese oxide was added to the boehmite gel. Finally, 10 kg of ZSM-5 molecular sieve and an appropriate amount of water were added, mixed thoroughly, and spray-dried to obtain catalyst microspheres. The catalyst microspheres were then soaked in a solution of 0.1 kg potassium hydroxide and 10 kg of water at room temperature for 5 hours, washed with water and filtered, and calcined at 600°C for 5 hours to obtain the shaped catalyst. The components in the catalyst, by mass ratio of oxides, are alumina:ZSM-5 molecular sieve:metal oxide:alkali metal additive = 40.9:48.4:8.3:2.3. Among them, the mass of metal oxide is the sum of nickel oxide and manganese oxide mixture formed by roasting nickel nitrate, and the mass of alkali metal additive is the sum of potassium oxide and magnesium oxide formed by roasting potassium hydroxide.

[0037] Low-carbon olefins can be produced by combining 50% crude oil and 50% Fischer-Tropsch light oil as feedstocks.

[0038] S1 Fischer-Tropsch light oil enters at the bottom of the riser reactor and undergoes a cracking reaction in contact with the catalyst at the bottom. The catalyst and the oil and gas generated by the cracking of Fischer-Tropsch 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-to-oil ratio is 30.

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

[0040] The product after the S3 reaction and the deactivated catalyst are separated in a separation system to obtain low-carbon olefins.

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

[0042] In this embodiment, the ethylene-propylene yield reached 51.2 wt% based on the total feed.

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

[0044] Table 1. Crude Oil Properties

[0045]

[0046]

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

[0048] Table 2. Properties of Fischer-Tropsch Synthetic Light Oil

[0049]

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

[0051] Table 3 Composition of Fischer-Tropsch Synthetic Light Oil

[0052]

[0053] Example 2

[0054] Catalysts for producing high yields of low-carbon olefins:

[0055] 9.2 kg of boehmite (65% by mass) was added to 180 kg of water and stirred until homogeneous. Nitric acid was then added to form a gel. 0.2 kg of magnesium oxide and 2 kg of nickel nitrate were then added and stirred at room temperature for 1 hour. The mixture was then heated to 40°C and aged for 4 hours, followed by cooling to 4°C for 5 hours. 3 kg of cobalt nitrate and 1.05 kg of cerium nitrate were added to the boehmite gel. Finally, 11.95 kg of ZSM-5 molecular sieve and an appropriate amount of water were added, mixed thoroughly, and spray-dried to obtain catalyst microspheres. The catalyst microspheres were then soaked in a solution of 0.1 kg of sodium hydroxide and 10 kg of water at room temperature for 5 hours, washed with water and filtered, and calcined at 600°C for 5 hours to obtain the shaped catalyst. The components in the catalyst, by mass ratio of oxides, are alumina:ZSM-5 molecular sieve:metal oxide:alkali metal additive = 30:60:8.5:1.4. Among them, the mass of metal oxide is the sum of the 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 alkali metal additive is the sum of the mixture of sodium oxide formed by roasting raw material sodium hydroxide and raw material magnesium oxide.

[0056] Production of low-carbon olefins:

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

[0058] Example 3

[0059] Catalysts for producing high yields of low-carbon olefins:

[0060] 14 kg of boehmite (65% by mass) was added to 180 kg of water and stirred until homogeneous. Nitric acid was then added to form a gel. Next, 2 kg of calcium nitrate and 5 kg of cobalt nitrate were added and stirred at room temperature for 1 hour. The mixture was then heated to 60°C and aged for 4 hours, followed by cooling to 6°C for 5 hours. 5 kg of cerium nitrate was added to the boehmite gel. Finally, 17 kg of ZSM-5 molecular sieve and an appropriate amount of water were added, mixed thoroughly, and spray-dried to obtain catalyst microspheres. The catalyst microspheres were then soaked in a solution of 0.2 kg potassium hydroxide and 10 kg water at room temperature for 5 hours, washed with water and filtered, and calcined at 600°C for 5 hours to obtain the shaped catalyst. The components in the catalyst, by mass ratio of oxides, are alumina:ZSM-5 molecular sieve:metal oxide:alkali metal additive = 30.1:56.3:10.8:2.8. Among them, the mass of metal oxide is the sum of the mixture of cobalt oxide and cerium oxide formed by calcining cobalt nitrate and cerium nitrate, and the mass of alkali metal additive is the sum of calcium oxide and potassium oxide formed by calcining calcium nitrate and potassium hydroxide.

[0061] Production of low-carbon olefins:

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

[0063] Example 4

[0064] Catalysts for producing high yields of low-carbon olefins:

[0065] 14 kg of boehmite (65% by mass) was added to 180 kg of water and stirred until homogeneous. Nitric acid was then added to form a gel. Next, 0.05 kg of calcium oxide, 0.2 kg of magnesium nitrate, and 2 kg of nickel oxide were added and stirred at room temperature for 1 hour. The mixture was then heated to 50°C and aged for 4 hours, followed by cooling to 8°C for 5 hours. 5 kg of cobalt nitrate and 4 kg of cerium nitrate were added to the boehmite gel. Finally, 11.95 kg of ZSM-5 molecular sieve and an appropriate amount of water were added, mixed thoroughly, and spray-dried to obtain catalyst microspheres. The catalyst microspheres were then soaked in a solution of 0.1 kg of sodium oxide and 30 kg of water at room temperature for 5 hours, washed with water and filtered, and calcined at 600°C for 5 hours to obtain the shaped catalyst. The components in the catalyst, by mass ratio of oxides, are alumina:ZSM-5 molecular sieve:metal oxide:alkali metal additive = 34.8:45.7:18.6:0.8. Among them, the mass of metal oxide is the sum of cobalt oxide and cerium oxide formed by roasting cobalt nitrate and cerium nitrate, and the mass of nickel oxide, and the mass of alkali metal additive is the sum of magnesium oxide and sodium oxide formed by roasting magnesium nitrate and sodium hydroxide, and the mass of calcium oxide,.

[0066] Production of low-carbon olefins:

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

[0068] Example 5

[0069] Catalysts for producing high yields of low-carbon olefins:

[0070] 12 kg of boehmite (65% by mass) was added to 180 kg of water and stirred until homogeneous. Nitric acid was then added to form a gel. Next, 0.05 kg of manganese oxide, 0.2 kg of magnesium nitrate, and 1 kg of nickel oxide were added and stirred at room temperature for 1 hour. The mixture was then heated to 40°C and aged for 4 hours, followed by cooling to 5°C for 5 hours. 2 kg of cobalt oxide and 1 kg of cerium oxide were added to the boehmite gel. Finally, 5.975 kg of ZSM-5 molecular sieve, 5.975 kg of SAPO-34 molecular sieve, and an appropriate amount of water were added and mixed thoroughly. The mixture was then spray-dried to obtain catalyst microspheres. The catalyst microspheres were soaked in a solution of 0.05 kg of sodium oxide and 30 kg of water at room temperature for 5 hours, then washed and filtered. The resulting precipitate was then calcined at 600°C for 5 hours to obtain the shaped catalyst. The components in the catalyst, by mass ratio of oxides, are: alumina: ZSM-5 molecular sieve: SAPO-34 molecular sieve: metal oxide: alkali metal additive = 32.6: 24.95: 24.95: 16.9: 0.6. Among them, the mass of metal oxide is the sum of the mass of the mixture of raw materials manganese oxide, nickel oxide, cobalt oxide and cerium oxide, and the mass of alkali metal additive is the sum of the mass of magnesium oxide and sodium oxide formed by calcining raw materials magnesium nitrate and sodium hydroxide.

[0071] Production of low-carbon olefins:

[0072] Similar to Example 1, except that 30% of Zhongyuan crude oil and 70% of Fischer-Tropsch light oil were used as raw materials. The contact temperature between the Fischer-Tropsch light oil and the catalyst was 650°C, the catalyst-to-oil ratio was 5, and the residence time was 3s. The reaction temperature at the outlet of the riser reactor was 600°C, the catalyst-to-oil ratio was 10, and the residence time was 3s. Based on the total feed, the ethylene-propylene yield reached 45.98 wt%.

[0073] Example 6

[0074] Catalysts for producing high yields of low-carbon olefins:

[0075] 14 kg of boehmite (65% by mass) was added to 180 kg of water and stirred until homogeneous. Nitric acid was then added to form a gel. Next, 2 kg of calcium nitrate and 5 kg of cobalt nitrate were added and stirred at room temperature for 1 hour. The mixture was then heated to 60°C and aged for 4 hours, followed by cooling to 3°C for 5 hours. 5 kg of cerium nitrate was added to the boehmite gel. Finally, 17 kg of ZSM-5 molecular sieve and an appropriate amount of water were added, mixed thoroughly, and then spray-dried to obtain catalyst microspheres. The catalyst microspheres were soaked in a solution of 0.2 kg potassium hydroxide and 10 kg water at room temperature for 5 hours, then washed and filtered. Finally, the mixture was calcined at 600°C for 5 hours to obtain the shaped catalyst. The components in the catalyst, by mass ratio of oxides, are alumina:ZSM-5 molecular sieve:metal oxide:alkali metal additive = 30.1:56.3:10.8:2.8. Among them, the mass of metal oxide is the sum of the mass of the cobalt oxide and cerium oxide mixture formed by roasting cobalt nitrate and cerium nitrate, and the mass of alkali metal additive is the sum of the mass of calcium oxide and potassium oxide formed by roasting calcium nitrate and potassium hydroxide.

[0076] Production of low-carbon olefins:

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

[0078] Comparative Example 1

[0079] 12 kg of boehmite (65% by mass) was added to 180 kg of water and stirred until homogeneous. Nitric acid was then added to form a gel. Next, 1.2 kg of manganese oxide and 5 kg of cobalt nitrate were added and stirred at room temperature for 1 hour. The mixture was then heated to 60°C and aged for 4 hours, followed by cooling to 2°C for 5 hours. 5 kg of cerium nitrate and 2 kg of nickel nitrate were added to the boehmite gel. Finally, 16 kg of ZSM-5 molecular sieve and an appropriate amount of water were added, mixed thoroughly, and spray-dried to obtain catalyst microspheres. The catalyst microspheres were then soaked in a solution of 0.1 kg potassium hydroxide and 10 kg of water at room temperature for 5 hours, washed with water, filtered, and calcined at 600°C for 5 hours to obtain the shaped catalyst. The components in the catalyst, by mass ratio of oxides, are alumina:ZSM-5 molecular sieve:metal oxide:alkali metal additive = 27.1:55.4:17.3:0.3. Among them, the mass of metal oxide is the sum of the mass of cobalt oxide, cerium oxide and nickel oxide formed by roasting raw materials cobalt nitrate, cerium nitrate and nickel nitrate, and the mass of raw material manganese oxide mixture. The mass of alkali metal additive is the mass of potassium oxide formed by roasting raw material potassium hydroxide.

[0080] Using 50% crude oil and 50% Fischer-Tropsch light oil as feedstock, the ethylene and propylene yield reached 41.19 wt% based on the total feed.

[0081] Comparative Example 2

[0082] 35 kg of boehmite (65% by mass) was added to 180 kg of water and stirred until homogeneous. Nitric acid was then added to form a gel, followed by 3 kg of nickel nitrate, and the mixture was stirred at room temperature for 1 hour. The mixture was then heated to 60°C and aged for 4 hours, followed by cooling to 2°C for 5 hours. 6 kg of cobalt nitrate and 7 kg of cerium nitrate were added to the boehmite gel. Finally, 30 kg of ZSM-5 molecular sieve and an appropriate amount of water were added, mixed thoroughly, and spray-dried to obtain catalyst microspheres. The catalyst microspheres were then soaked in a solution of 0.05 kg of potassium hydroxide and 30 kg of water at room temperature for 5 hours, washed with water and filtered, and calcined at 600°C for 5 hours to obtain the shaped catalyst. The components in the catalyst, by mass ratio of oxides, are alumina:ZSM-5 molecular sieve:metal oxide:alkali metal additive = 39.3:51.8:8.8:0.07. Among them, the mass of metal oxide is the sum of the mass of the mixture of cobalt oxide, nickel oxide and cerium oxide formed by roasting cobalt nitrate, nickel nitrate and cerium nitrate, and the mass of alkali metal additive is the mass of potassium oxide formed by roasting potassium hydroxide.

[0083] Using 30% crude oil from the Central Plains and 70% Fischer-Tropsch light oil as feedstock, the ethylene and propylene yield reached 42.99 wt% based on the total feed.

[0084] A comparative analysis of the reaction results of Examples 1-6 and Comparative Examples 1-2 shows that: the catalyst prepared in Comparative Example 1 has too low an alumina content, fewer acid centers with larger pore sizes, low feed conversion rate, and low yield of ethylene + propylene; the catalyst prepared in Comparative Example 2 has a low proportion of alkali metals, resulting in strong acid centers, which leads to excessive hydrogen transfer reaction and low olefin yield; the catalysts prepared in Examples 1-6 have suitable component contents and high yields of ethylene and propylene.

[0085] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.

Claims

1. A method for applying a catalyst in the production of low-carbon olefins from light oil and crude oil in the Fischer-Tropsch synthesis, characterized in that, include: S1 Fischer-Tropsch light oil enters at the bottom of the riser reactor and comes into contact with the catalyst at the bottom for cracking reaction. The catalyst and the oil and gas generated by the cracking of Fischer-Tropsch light oil move to the middle of the riser reactor. S2 crude oil enters the middle of the riser reactor and encounters the catalyst and oil and gas produced by the cracking of Fischer-Tropsch light oil after the reaction, and the reaction products and deactivated catalyst continue to move upward and flow out of the riser reactor outlet. S3 separates the reaction products from the deactivated catalyst to obtain low-carbon olefins; The catalyst used in the application method comprises the following components by mass parts: 0.1-30 parts of the active metal component; 30-80 parts of molecular sieve; 30-60 parts adhesive; Metal additives: 0.1-5 parts; The metal additives include one or more of Mg, Ca, K and Na; The active metal component is one or more of Mo, Mn, Ce and Ni.

2. The application method as described in claim 1, characterized in that, The molecular sieve is one or both of SAPO-34 and ZSM-5 molecular sieves.

3. The application method as described in claim 1, characterized in that, The binder is boehmite.

4. The application method as described in claim 1, characterized in that, The method for preparing the catalyst includes: After the binder is added to water and stirred evenly, nitric acid is added to form a gel. Then, nitrates or oxides containing metal active components are added in sequence for temperature-variable aging. Finally, metal additives and molecular sieves are added and mixed evenly. After drying and calcination, the catalyst is obtained.

5. The application method as described in claim 4, characterized in that, The variable temperature aging process is divided into at least two stages, namely a first stage and a second stage; the aging temperature of the first stage is 40-70℃, and the aging temperature of the second stage is 1-10℃.

6. The application method as described in claim 5, characterized in that, The aging temperature for the first stage is 40-60℃, and the aging temperature for the second stage is 2-8℃.

7. The application method as described in claim 1, characterized in that, The reaction conditions in S1 are: reaction temperature 650-800℃, residence time 0.5-3s, and agent-to-oil ratio 5-50.

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

9. The application method as described in claim 1, characterized in that, Also includes: The deactivated catalyst after S4 separation is regenerated by the regeneration reactor, and the regenerated catalyst is returned to the bottom of the riser reactor for recycling.

10. The application method as described in claim 9, characterized in that, The catalyst regeneration temperature in S4 is 700-800℃.

11. The application method as described in claim 10, characterized in that, The catalyst regeneration temperature in S4 is 720-800℃.

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