Catalytic cracking method for preparing ethylene and propylene

Abstract

The invention relates to a catalytic cracking method for preparing ethylene and propylene, which comprises the following steps: introducing a catalytic cracking catalyst before reaction into a reactor to contact with a hydrocarbon oil raw material for catalytic cracking reaction, and then carrying out gas-solid separation to obtain the catalytic cracking catalyst after reaction and an oil gas product. The temperature of the catalytic cracking catalyst before the reaction is above 650 DEG C, and the specific heat capacity is 1.1-2.5 J / (g.K); the difference between the temperature of the catalytic cracking catalyst after the reaction and the temperature of the catalytic cracking catalyst before the reaction is 20-100 DEG C. By adopting the catalytic cracking catalyst with high specific heat capacity, the problem that the surface temperature drop of the catalyst is too large in the catalytic cracking reaction process is effectively inhibited, the influence of the temperature drop on the cracking reaction process of the light raw material is weakened, the single-molecule cracking of the raw material is promoted, the yield of ethylene and propylene in the product is increased, and the yield of propylene is increased. The efficient utilization of the raw materials is promoted.

Description

Technical Field

[0001] The invention belongs to the field of petroleum processing, and in particular relates to a catalytic cracking method for preparing ethylene and propylene. Background Art

[0002] Light olefins are important petrochemical raw materials. Common technologies for producing light olefins include steam cracking, catalytic cracking, olefin cracking and methanol to olefins. The operation process of the catalytic cracking unit includes a heat balance of periodic heat supply and heat extraction. During the catalytic cracking reaction, the coke deposited on the catalyst burns in the regenerator to generate heat, which is brought to the reactor by the regenerated catalyst to heat the raw material and provide cracking reaction heat.

[0003] Catalytic cracking reaction is a strong endothermic process. The conventional catalytic cracking reaction heat is about 180-300 kJ / kg of raw oil, while the catalytic cracking technology for producing light olefins, such as deep catalytic cracking process (DCC) and catalytic thermal cracking process (CPP), has a greater demand for heat, and the cracking reaction heat can reach 600-800 kJ / kg of raw material. If the molecules in the raw material are smaller, the reaction heat will usually increase. For example, when using naphtha or olefins with a carbon number not higher than 12 to produce light olefins, a higher reaction heat is required. In order to meet the required reaction heat, the method commonly used in the prior art is to increase the agent-oil ratio, but a high agent-oil ratio usually brings about the problem of increasing the production of coke and dry gas yield. In this regard, those skilled in the art propose to replace part of the conventional catalytic cracking catalyst with an inert carrier, such as using amorphous aluminum silicate, coal powder and catalytic cracking waste catalyst as heat carriers in CN101580733A; CN107868675A uses a mixture of silicon oxide, titanium oxide and aluminum oxide as a heat carrier to partially replace the catalyst. There are also some methods that aim to meet the overall heat demand of the catalytic cracking reactor. For example, US6558530 adopts a method of gasifying the raw material before injecting it into the reactor; US7572362 uses sand as a heat carrier to pre-treat the raw material and then feed it into the reactor.

[0004] During the actual production process, after the heat carried by the regenerated catalyst supplies the raw material temperature and reaction heat, its temperature drops to below the optimal temperature required for raw material conversion. If the temperature of the catalyst to be regenerated is further increased, the temperature of the regenerated catalyst at the initial stage of the reaction in contact with the raw material will be higher than the optimal temperature, increasing by-products. Summary of the invention

[0005] The object of the present invention is to increase the yield of ethylene and propylene in the catalytic cracking products of light raw materials.

[0006] In order to achieve the above object, the present invention provides a catalytic cracking method for preparing ethylene and propylene, the method comprising the following steps:

[0007] The catalytic cracking catalyst before the reaction is introduced into a reactor to contact with a hydrocarbon oil feedstock for a catalytic cracking reaction, and then a gas-solid separation is performed to obtain a catalytic cracking catalyst after the reaction and an oil and gas product; the temperature of the catalytic cracking catalyst before the reaction is above 650°C, and the specific heat capacity is 1.1 to 2.5 J / (g·K); the difference between the temperature of the catalytic cracking catalyst after the reaction and the temperature of the catalytic cracking catalyst before the reaction is 20 to 100°C.

[0008] Optionally, the temperature of the catalytic cracking catalyst before the reaction is above 680°C, and the specific heat capacity is 1.2-2.0 J / (g·K); the temperature difference between the catalytic cracking catalyst after the reaction and the temperature of the catalytic cracking catalyst before the reaction is 30-90°C.

[0009] Optionally, the conditions of the catalytic cracking reaction include: a reaction temperature of 580 to 800° C., preferably 600 to 720° C.; a reaction pressure of 0.05 to 1 MPa, preferably 0.1 to 0.8 MPa; a reaction time of 0.1 to 80 s, preferably 0.5 to 70 s; and a mass ratio of the catalytic cracking catalyst to the raw material of (3 to 180):1, preferably (10 to 150):1.

[0010] Optionally, the reaction flow after the catalytic cracking reaction in the reactor is quickly cooled to below 530° C. before gas-solid separation is performed on the reaction flow.

[0011] Optionally, the catalytic cracking catalyst comprises a medium-pore zeolite, a carrier and an auxiliary component; the auxiliary component is an inert inorganic compound; on a dry basis and based on the total weight of the catalytic cracking catalyst, the catalytic cracking catalyst comprises 1 to 50 weight percent of the medium-pore zeolite, 5 to 89 weight percent of the auxiliary component and 10 to 70 weight percent of the carrier; the medium-pore zeolite is selected from at least one of the ZSM-5 series zeolites and the ZRP zeolite; the carrier comprises clay and an inorganic oxide; the clay is selected from at least one of kaolin, halloysite, montmorillonite, diatomaceous earth, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite; the inorganic oxide is selected from at least one of silicon dioxide and aluminum oxide.

[0012] Optionally, the inert inorganic compound includes at least one of silicon dioxide, titanium dioxide, aluminum oxide, silicon carbide, aluminum nitride, boron nitride, boron oxide, manganese oxide, silicon nitride and mullite.

[0013] Optionally, the method for preparing the catalytic cracking catalyst comprises the following steps: uniformly mixing the carrier, the medium-pore zeolite and the auxiliary agent components, spray drying and calcining.

[0014] Optionally, the hydrocarbon oil feedstock is fed in gas phase after heat exchange gasification, and the feed temperature of the hydrocarbon oil feedstock is 100-400°C, preferably 150-300°C; the hydrocarbon oil feedstock is C4-C8 olefin or a mixture containing C4-C8 olefin; the content of C4-C8 olefin in the mixture containing C4-C8 olefin is 50-100wt%, preferably 80-100wt%.

[0015] Optionally, the reactor is selected from one or a series combination of a riser, a fluidized bed with a constant linear velocity, a fluidized bed with a constant diameter, an upward conveying line and a downward conveying line; the riser is a constant diameter riser reactor or a variable diameter fluidized bed reactor.

[0016] Optionally, the method further includes the steps of: charring and regenerating the catalytic cracking catalyst after the reaction to obtain a regenerated catalytic cracking catalyst; returning the regenerated catalytic cracking catalyst to the reactor after fuel combustion to supplement heat; the charring and regeneration of the catalytic cracking catalyst after the reaction is carried out in an oxygen-containing atmosphere, and the reaction temperature of the charring and regeneration is 600-800°C; the oxygen content in the oxygen-containing atmosphere is not higher than 28% by volume.

[0017] Through the above technical scheme, the present invention adopts a catalytic cracking catalyst with a high specific heat capacity, effectively suppresses the phenomenon of obvious temperature drop on the catalyst surface during the catalytic cracking reaction, weakens the influence of temperature drop on the cracking reaction process of light raw materials, promotes single-molecule cracking of raw materials, improves the yield of ethylene and propylene in the product, and promotes efficient utilization of raw materials.

[0018] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It is a schematic diagram of the catalytic cracking process of one embodiment of the present invention.

[0021] Description of Reference Numerals

[0022] 1 pipeline 2 reactor 3 pipeline

[0023] 4 pipelines 5 pipelines 6 pipelines

[0024] 7 outlet section 8 settler 9 gas collecting chamber

[0025] 10 stripping section 11 pipeline 12 inclined pipe to be produced

[0026] 13 regenerator 14 pipeline 15 cyclone separation system

[0027] 16 pipeline 17 energy recovery system 18 heat collector

[0028] 19 Regeneration inclined tube 20 Large oil and gas pipeline 21 Product fractionation device DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0030] In the process of producing light olefins using light olefins and / or alkanes as raw materials, since the catalytic cracking reactor has no external heat source, the temperature of the catalyst decreases significantly during the reaction, thereby reducing the yield of the target product. After experiments, the inventors found that the reason for the decrease in the yield of the target product is that the decrease in the temperature of the catalyst affects the cracking mechanism of the raw material. It was further found that by inhibiting or delaying the decrease in the catalyst temperature, the selective cracking of the raw material molecules can be promoted, and the yield of ethylene and propylene in the product can be increased. In view of this, the scheme of the present invention is proposed.

[0031] The present invention provides a catalytic cracking method for preparing ethylene and propylene, the method comprising the following steps:

[0032] The catalytic cracking catalyst before the reaction is introduced into a reactor to contact with a hydrocarbon oil feedstock for a catalytic cracking reaction, and then a gas-solid separation is performed to obtain a catalytic cracking catalyst after the reaction and an oil and gas product; the temperature of the catalytic cracking catalyst before the reaction is above 650°C, and the specific heat capacity is 1.1 to 2.5 J / (g·K); the difference between the temperature of the catalytic cracking catalyst after the reaction and the temperature of the catalytic cracking catalyst before the reaction is 20 to 100°C.

[0033] The present invention adopts a catalytic cracking catalyst with a high specific heat capacity, thereby effectively suppressing the phenomenon of obvious temperature drop during the catalytic cracking reaction, weakening the influence of the temperature drop on the cracking reaction process of light raw materials, promoting the single-molecule cracking of the raw materials, improving the yield of ethylene and propylene in the product, and promoting the efficient utilization of the raw materials.

[0034] The temperature of the catalytic cracking catalyst before the reaction is above 680° C., and the specific heat capacity is 1.2 to 2.0 J / (g·K).

[0035] In a specific embodiment of the present invention, the difference between the temperature of the catalytic cracking catalyst after the reaction and the temperature of the catalytic cracking catalyst before the reaction can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C or any value within the aforementioned range.

[0036] Preferably, the difference between the temperature of the catalytic cracking catalyst after the reaction and the temperature of the catalytic cracking catalyst before the reaction is 30 to 90°C.

[0037] The present invention uses the above-mentioned catalytic cracking catalyst, which can reduce the amount of catalytic cracking catalyst used on the basis of meeting the heat required by the entire reaction system, thereby reducing costs, and can also avoid the phenomenon of increased coke and dry gas yields under high catalyst-to-oil ratio conditions, which is beneficial to improving the utilization rate of petrochemical products.

[0038] Wherein, the conditions of the catalytic cracking reaction include: reaction temperature of 580-800°C, preferably 600-720°C; reaction pressure of 0.05-1MPa, preferably 0.1-0.8MPa; reaction time of 0.1-80s, preferably 0.5-70s; mass ratio of the catalytic cracking catalyst to the raw material is (3-180):1, preferably (10-150):1. By adopting the above reaction conditions, the cracking reaction of light raw materials can be ensured to proceed smoothly. By adopting a catalytic cracking catalyst with high specific heat capacity, the reaction conditions of high catalyst-to-oil ratio can be avoided, thereby avoiding the situation where the yield of coke and dry gas in the product increases.

[0039] It should be noted that the above reaction conditions can be adjusted according to the type of reactor.

[0040] The hydrocarbon oil feedstock is fed in gas phase after heat exchange gasification, and the feed temperature of the hydrocarbon oil feedstock is 100-400°C, preferably 150-300°C. Preheating the hydrocarbon oil feedstock to a suitable reaction temperature and feeding it in gas phase can promote the unimolecular cracking of light feedstock. The reaction flow after the catalytic cracking reaction in the reactor is rapidly cooled to below 530°C before gas-solid separation. It should be noted that in the present invention, "rapid cooling" means cooling to the target temperature within 2 seconds or even shorter.

[0041] The catalytic cracking catalyst comprises a medium-pore zeolite, a carrier and an auxiliary component; the auxiliary component is an inert inorganic compound.

[0042] In a specific embodiment of the present invention, the catalytic cracking catalyst comprises 1 to 50 weight % of medium-pore zeolite, 5 to 89 weight % of auxiliary component and 10 to 70 weight % of carrier, calculated on a dry basis and based on the total weight of the catalytic cracking catalyst; the medium-pore zeolite is selected from at least one of ZSM-5 series zeolites and ZRP zeolites; the carrier comprises clay and inorganic oxides; the clay is selected from at least one of kaolin, halloysite, montmorillonite, diatomaceous earth, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite; the inorganic oxide is selected from at least one of silicon dioxide and aluminum oxide.

[0043] In the present invention, the active component in the catalytic cracking catalyst is mixed with an inert inorganic compound with a high specific heat capacity and then formed, and the inert inorganic compound is evenly distributed, which is more conducive to heat conduction. The active component in the catalytic cracking catalyst is a medium-pore zeolite, and the other components have low activity and will not have an adverse effect on the catalytic cracking reaction of light raw materials.

[0044] The inert inorganic compound includes at least one of silicon dioxide, titanium dioxide, aluminum oxide, silicon carbide, aluminum nitride, boron nitride, boron oxide, manganese oxide, silicon nitride and mullite. By selecting the inert inorganic compound with high specific heat capacity, the requirement for greater heat demand of the catalytic cracking reaction of low carbon number raw materials can be met, the phenomenon of a significant decrease in the temperature of the catalytic cracking catalyst can be significantly suppressed, and the selective cracking of the raw material molecules can be promoted, thereby increasing the yield of ethylene and propylene.

[0045] The preparation method of the catalytic cracking catalyst comprises the following steps: uniformly mixing the carrier, the medium-pore zeolite and the auxiliary agent component, spray drying and calcining. For example, in a specific embodiment of the present invention, a certain amount of kaolin, pseudo-boehmite and hydrochloric acid can be uniformly mixed, aged, and then a certain amount of inert inorganic compound with high specific heat capacity and zeolite are added, and the slurry is uniformly stirred and spray dried to obtain the catalytic cracking catalyst.

[0046] The hydrocarbon oil raw material is C4-C8 olefin or a mixture containing C4-C8 olefin; the content of C4-C8 olefin in the mixture containing C4-C8 olefin is 50-100wt%, preferably 80-100wt%. Particularly preferably, the hydrocarbon oil raw material is pure olefin. It should be noted that C4-C8 olefin refers to olefin with 4 to 8 carbon atoms.

[0047] Wherein, the reactor is selected from one or a series combination of a riser, a fluidized bed with a constant linear velocity, a fluidized bed with a constant diameter, an upward conveying line and a downward conveying line; the riser is a riser reactor with a constant diameter or a fluidized bed reactor with a variable diameter.

[0048] In a specific embodiment, the catalytic cracking catalyst with a high specific heat capacity can be added to the reaction zone as needed. For example, the reactor is a variable diameter fluidized bed reactor, including a first reaction zone and a second reaction zone. In a specific implementation, the catalytic cracking catalyst can be introduced into the first reaction zone or the second reaction zone, or introduced into the first reaction zone and the second reaction zone respectively, according to the situation. The mass ratio of the catalyst and the inert inorganic compound can also be adjusted as needed to enhance the ability of the catalytic cracking catalyst to provide heat for the reaction and reduce the temperature drop of the catalytic cracking catalyst during the reaction.

[0049] The method further comprises the steps of: charring and regenerating the catalytic cracking catalyst after the reaction to obtain a regenerated catalytic cracking catalyst; returning the regenerated catalytic cracking catalyst to the reactor after fuel combustion to supplement heat; charring and regenerating the catalytic cracking catalyst after the reaction in an oxygen-containing atmosphere, the charring and regeneration reaction temperature being 600 to 800°C; and the oxygen content in the oxygen-containing atmosphere being no higher than 28% by volume.

[0050] Figure 1 A schematic flow diagram of a catalytic cracking method provided by the present invention is shown in FIG. Figure 1 As shown, the pre-lifting medium is introduced into the reactor 2 through the pipeline 1, and the pre-reaction catalytic cracking catalyst from the regeneration inclined tube 19 moves upward under the action of the pre-lifting medium. The preheated gasified hydrocarbon oil feedstock from the pipeline 3 and the atomized steam from the pipeline 4 are injected into the bottom of the reactor 2 together, contacting with the pre-reaction catalytic cracking catalyst to produce a catalytic cracking reaction and move upward along the reactor 2. The oil and gas products after the reaction and the catalytic cracking catalyst after the reaction enter the cyclone separator of the settler 8 through the outlet section 7 of the reactor 2 to separate the catalytic cracking catalyst after the reaction and the oil and gas products. The oil and gas products enter the gas collecting chamber 9, and the reaction oil and gas in the gas collecting chamber 9 enter the subsequent product fractionation device 21 through the large oil and gas pipeline 20.

[0051] It should be noted that the oil and gas products after the reaction and the catalytic cracking catalyst after the reaction are also rapidly cooled to below 530° C. by a heat medium before leaving the reactor 2 .

[0052] The catalytic cracking catalyst after the reaction returns from the feed leg to the settler 8 and enters the stripping section 10, where the stripping medium introduced through the pipeline 11 strips out the adsorbed reaction oil gas, and then enters the regenerator 13 through the regenerated inclined pipe 12 to contact with the oxygen-containing gas from the pipeline 14 to burn off the coke loaded thereon. The burnt regenerated catalyst and the flue gas enter the cyclone separator 15 for separation, and the separated flue gas enters the flue gas energy recovery system 17 through the pipeline 16 to recover energy. The regenerated catalyst returns to the bottom of the regenerator 13 and is supplemented with heat by the heat collector 18, and then returns to the reactor 2 through the regeneration inclined pipe 19.

[0053] In another embodiment of the present invention, the reactor is a variable diameter fluidized bed reactor, for example, reactor 2 includes a first reaction zone I and a second reaction zone II, and the hot regenerated catalyst can be introduced into the reactor through the side of the first reaction zone or the second reaction zone. For example, the hot regenerated catalyst from pipeline 5 enters the second reaction zone under the action of the medium from pipeline 6 and mixes with the catalyst to supplement heat for the reaction system.

[0054] The present invention is further described in detail by the following examples, but is not limited thereto. The raw materials used in the examples can be obtained through commercial sources. Among them, the raw material used in the examples and comparative examples is 1-hexene.

[0055] The ZRP-1 molecular sieve is produced by the catalyst plant of Qilu Petrochemical Company, wherein SiO2 / Al2O3=30 and the rare earth content RE2O3=2.0 wt%.

[0056] Halloysite kaolin is an industrial product produced by Suzhou Clay Company, with a solid content of 71.6% by weight.

[0057] Pseudo-boehmite is an industrial product of Shandong Aluminum Plant, with a solid content of 63% by weight.

[0058] The aluminum sol was produced by the catalyst plant of Qilu Petrochemical Company, and the Al2O3 content was 21.7% by weight.

[0059] Example 1

[0060] In this embodiment, catalytic cracking catalyst D1 is prepared, and its preparation method comprises the following steps:

[0061] (1) Preparation of mesoporous molecular sieves with MFI structure

[0062] S1, weigh 20g NH4Cl and dissolve it in 1000g water, then add 100g (dry basis) of crystallized product ZRP-1 molecular sieve to the NH4Cl solution, exchange at 90°C for 0.5 hour and filter to obtain a filter cake;

[0063] S2, weigh 4.0 g H3PO4 (concentration of 85 weight %) and 4.5 g Fe(NO3)3 and dissolve them in 90 g water to obtain a mixed solution containing phosphorus and iron;

[0064] S3, impregnating the filter cake with the mixed solution containing phosphorus and iron, drying; and then calcining at 550°C for 2 hours to obtain an MFI mesoporous molecular sieve containing phosphorus and iron. The elemental analysis chemical composition of the obtained molecular sieve is: 0.1Na2O·5.1Al2O3·2.4P2O5·1.5Fe2O3·3.8RE2O3·88.1SiO2.

[0065] (2) Weigh 75.4 kg of halloysite and slurry it with 250 kg of decationized water, add 54.8 kg of pseudo-boehmite, stir evenly, adjust the pH to 2-4 with hydrochloric acid, and age at 60-70° C. for 1 hour while maintaining the pH at 2-4, then reduce the temperature of the slurry to below 60° C., add 41.5 kg of aluminum sol to the slurry, and stir for 40 minutes to obtain a mixed slurry.

[0066] (3) adding the phosphorus and iron-containing MFI mesoporous molecular sieve (24.5 kg on a dry basis) prepared in step (1) to the mixed slurry obtained in step (2), stirring evenly, spray drying to form, and washing with diammonium phosphate solution (phosphorus content of 1 wt%) to remove free Na + , and dried to obtain catalytic conversion catalyst D1.

[0067] Based on the total dry weight of the catalyst D1, the dry composition of the catalyst includes: 20 wt% of MFI medium-porous molecular sieve containing phosphorus and iron, 28 wt% of pseudo-boehmite and 8 wt% of aluminum sol, and the balance is kaolin.

[0068] Example 2

[0069] The method for preparing catalytic cracking catalyst C1 in this example is carried out by referring to Example 1, and the difference between this method and Example 1 is that:

[0070] In step (3), the phosphorus and iron-containing MFI mesoporous molecular sieve (24.5 kg on a dry basis) prepared in step (1) and the inert inorganic compound are added to the mixed slurry obtained in step (2), stirred evenly, spray-dried to form, and washed with diammonium phosphate solution (phosphorus content of 1 wt%) to remove free Na + , and dried to obtain the catalytic conversion catalyst C1. The chemical composition of the inert inorganic compound includes: 30 mass % manganese oxide, 15 mass % aluminum oxide, 5 mass % titanium dioxide, 10 mass % boron oxide and 40 mass % silicon dioxide.

[0071] Based on the total dry weight of catalyst C1, the dry composition of the catalyst includes: 17 wt% of MFI medium-pore molecular sieve containing phosphorus and iron, 15 wt% of pseudo-boehmite, 8 wt% of aluminum sol and 16 wt% of inert inorganic compound, and the balance is kaolin.

[0072] Example 3

[0073] The method for preparing catalytic cracking catalyst C2 in this example is carried out with reference to Example 1, and the difference between this method and Example 1 is that:

[0074] In step (3), the phosphorus and iron-containing MFI mesoporous molecular sieve (24.5 kg on a dry basis) prepared in step (1) and the inert inorganic compound are added to the mixed slurry obtained in step (2), stirred evenly, spray-dried to form, and washed with diammonium phosphate solution (phosphorus content of 1 wt%) to remove free Na + , and dried to obtain the catalytic conversion catalyst C2. The chemical composition of the inert inorganic compound includes: 30 mass % manganese oxide, 15 mass % aluminum oxide, 5 mass % titanium dioxide, 10 mass % boron oxide and 40 mass % silicon dioxide.

[0075] Based on the total dry weight of catalyst C2, the dry composition of the catalyst includes: 14 wt% of MFI medium-pore molecular sieve containing phosphorus and iron, 10 wt% of pseudo-boehmite, 8 wt% of aluminum sol and 24 wt% of inert inorganic compound, and the balance is kaolin.

[0076] Example 4

[0077] The experiment of this example was Figure 1 The process shown in the figure is carried out on a medium-sized device of a riser reactor. 1-Hexene and a high-temperature catalytic cracking catalyst C1 are contacted in the riser reactor for catalytic cracking reaction. The reacted logistics and the reacted catalytic cracking catalyst are cooled and then enter a cyclone separator for gas-solid separation. Then the separated reaction oil and gas are introduced into a subsequent product fractionation device. The reacted catalyst is introduced into a regenerator for char regeneration and then returned to the riser reactor to continue to participate in the reaction. The reaction conditions and product distribution are shown in Table 1.

[0078] Example 5

[0079] The test of this embodiment is carried out according to Figure 1 The process shown in the figure is carried out, which differs from Example 4 in that the catalyst used is the catalyst C2 prepared in Example 3. The reaction conditions and product distribution are shown in Table 1.

[0080] Comparative Example 1

[0081] The test of comparative example 1 was carried out according to Figure 1 The process shown in the figure is carried out, which is different from Example 4 in that the catalyst used is the catalyst D1 prepared in Example 1. The reaction conditions and product distribution are shown in Table 1.

[0082] Table 1

[0083]

[0084]

[0085] As can be seen from Table 1, the method of the present invention is used to carry out catalytic cracking of light raw materials to prepare light olefins. Due to the use of a high specific heat capacity catalytic cracking catalyst, the phenomenon of temperature reduction during the catalytic cracking reaction is significantly suppressed, which weakens the effect of temperature drop on the cracking reaction process of light raw materials, enhances the single molecule cracking of the raw materials, improves the yield of ethylene and propylene, and promotes the efficient utilization of raw materials.

[0086] At the same time, the method provided by the present invention can also reduce the amount of catalytic cracking catalyst used while meeting the overall heat demand of the reaction system. On the one hand, it can reduce costs, and on the other hand, it can avoid the increase in coke and dry gas yields caused by high catalyst-to-oil ratio conditions, thereby improving the utilization rate of petrochemical resources.

[0087] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0088] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0089] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A catalytic cracking method for producing ethylene and propylene, characterized in that: The method comprises the following steps: The catalytic cracking catalyst before the reaction is introduced into a reactor to contact with a hydrocarbon oil feedstock for a catalytic cracking reaction, and then a gas-solid separation is performed to obtain a catalytic cracking catalyst after the reaction and an oil and gas product; the temperature of the catalytic cracking catalyst before the reaction is above 650°C, and the specific heat capacity is 1.1 to 2.5 J / (g·K); the difference between the temperature of the catalytic cracking catalyst after the reaction and the temperature of the catalytic cracking catalyst before the reaction is 20 to 100°C.

2. The catalytic cracking method according to claim 1, wherein: The temperature of the catalytic cracking catalyst before the reaction is above 680°C, and the specific heat capacity is 1.2 to 2.0 J / (g·K); The difference between the temperature of the catalytic cracking catalyst after the reaction and the temperature of the catalytic cracking catalyst before the reaction is 30 to 90°C.

3. The catalytic cracking method according to claim 1, wherein: The conditions of the catalytic cracking reaction include: a reaction temperature of 580 to 800°C, preferably 600 to 720°C; The reaction pressure is 0.05-1 MPa, preferably 0.1-0.8 MPa; The reaction time is 0.1 to 80 seconds, preferably 0.5 to 70 seconds; The mass ratio of the catalytic cracking catalyst to the raw material is (3-180):1, preferably (10-150):

1.

4. The catalytic cracking method according to claim 1, wherein: Before performing gas-solid separation on the reaction flow after the catalytic cracking reaction in the reactor, the reaction flow is quickly cooled to below 530°C.

5. The catalytic cracking method according to claim 1, wherein: The catalytic cracking catalyst comprises a medium-pore zeolite, a carrier and an auxiliary component; the auxiliary component is an inert inorganic compound; On a dry basis and based on the total weight of the catalytic cracking catalyst, the catalytic cracking catalyst comprises 1 to 50 weight percent of a medium-pore zeolite, 5 to 89 weight percent of an auxiliary component and 10 to 70 weight percent of a carrier; The medium-pore zeolite is selected from at least one of ZSM-5 series zeolites and ZRP zeolites; The carrier includes clay and inorganic oxide; The clay is selected from at least one of kaolin, halloysite, montmorillonite, diatomaceous earth, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite; The inorganic oxide is selected from at least one of silicon dioxide and aluminum oxide.

6. The catalytic cracking method according to claim 5, wherein: The inert inorganic compound includes at least one of silicon dioxide, titanium dioxide, aluminum oxide, silicon carbide, aluminum nitride, boron nitride, boron oxide, manganese oxide, silicon nitride and mullite.

7. The catalytic cracking method according to claim 5, wherein: The preparation method of the catalytic cracking catalyst comprises the following steps: uniformly mixing the carrier, the medium-pore zeolite and the auxiliary agent component, spray drying and calcining.

8. The catalytic cracking method according to claim 1, wherein: The hydrocarbon oil raw material is fed in gas phase after heat exchange gasification, and the feed temperature of the hydrocarbon oil raw material is 100-400°C, preferably 150-300°C; The hydrocarbon oil raw material is C4-C8 olefins or a mixture containing C4-C8 olefins; The content of C4-C8 olefins in the mixture containing C4-C8 olefins is 50-100 wt%, preferably 80-100 wt%.

9. The catalytic cracking method according to claim 1, wherein: The reactor is selected from one or a series combination of a riser, a fluidized bed with a constant linear velocity, a fluidized bed with a constant diameter, an upward conveying line and a downward conveying line; The riser is a constant diameter riser reactor or a variable diameter fluidized bed reactor.

10. The catalytic cracking method according to claim 1, wherein: The method further comprises the steps of: The catalytic cracking catalyst after the reaction is charred and regenerated to obtain a regenerated catalytic cracking catalyst; the regenerated catalytic cracking catalyst is returned to the reactor after fuel combustion to supplement heat; The charring regeneration of the catalytic cracking catalyst after the reaction is carried out in an oxygen-containing atmosphere, and the reaction temperature of the charring regeneration is 600-800° C.; the oxygen content in the oxygen-containing atmosphere is not higher than 28% by volume.

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