Catalytic cracking method for producing more ethylene and propylene

Abstract

Provided in the present invention is a catalytic cracking method for producing more ethylene and propylene from hydrocarbons. The method comprises: S1, bringing a hydrocarbon raw material in contact with a catalyst in a reactor system to perform reaction, so as to obtain a reaction oil agent, wherein the reactor system at least comprises two reaction zones: a first reaction zone and a second reaction zone downstream the first reaction zone, the hydrocarbon raw material is introduced below or from the lower part of the first reaction zone, the volume proportion of a zone where the average solid content of the catalyst in the first reaction zone is greater than 0.2 is greater than 0.2 is 0.2-0.7 in the first reaction zone, and the average solid content of the catalyst in the second reaction zone is less than 0.1; S2, subjecting the reaction oil agent to gas-solid separation, so as to obtain a carbon deposit catalyst and oil and gas; and S3, regenerating the carbon deposit catalyst, and returning the obtained regenerated catalyst to the reactor for recycling. In the present invention, a high solid content of the catalyst is used in the initial stage of the reaction to increase the contact between hydrocarbon molecules and an active center of the catalyst, such that the proportion of the catalytic cracking reaction is significantly increased, and the degree of the thermal cracking reaction is reduced; and a relatively low solid content of the catalyst is used in the subsequent stage of the reaction, such that re-conversion of the generated ethylene and propylene is reduced, the hydrogen transfer reaction and condensation reaction are reduced, and the yield ratio of diene / (methane + coke) is greatly increased.

Description

A catalytic cracking method for producing ethylene and propylene in large quantities Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to a catalytic cracking method for producing ethylene and propylene in large quantities. Background Technology

[0002] Important organic chemical raw materials such as ethylene and propylene play an irreplaceable role in many fields, including chemical engineering, agriculture, and medicine. Domestically and internationally, the production of low-carbon olefins, including ethylene and propylene, often uses light hydrocarbons or light naphtha fractions as feedstocks and employs steam cracking processes. Although decades of research and development have advanced steam cracking technology, resulting in numerous technological improvements, its drawbacks remain, including high energy consumption, high production costs, difficulty in adjusting product structure, and large CO2 emissions. Catalytic cracking technology, as an important secondary crude oil processing technology, is increasingly gaining widespread attention due to its advantages such as strong feedstock adaptability and flexible product formulations. In particular, the innovation of ZSM-5 molecular sieve has driven progress in catalytic cracking technology for the production of low-carbon olefins.

[0003] Numerous research institutions and oil companies both domestically and internationally have developed proprietary catalytic cracking technologies for producing low-carbon olefins, including typical examples such as the DCC, Maxofin, and PetroFCC processes. Over the past few decades, continuous optimization and redesign of catalytic cracking processes and catalysts have led to continuously improved yields of low-carbon olefins and reduced yields of dry gas and coke. Patented technologies developed during this research and development process primarily include the development of various reactors, such as riser + fluidized bed reactors, dual riser reactors, downflow reactors, and variable diameter riser reactors; and the development of different specialized catalyst preparation technologies, mainly including ZSM-5 molecular sieve modification, Y molecular sieve and matrix composition modification. These catalytic cracking technologies, using heavy oil as feedstock, achieve 2%-6% ethylene yield, 15%-25% propylene yield, and 10%-20% butene yield. While existing catalytic cracking technologies can achieve relatively high propylene and butene yields, ethylene yields remain low, and research findings are limited.

[0004] CN1069016A discloses a method for the direct conversion of heavy hydrocarbons to ethylene. In this method, a solid particulate contact agent is used to react with feedstock oil in a fluidized bed or plug flow reactor, particularly a downflow tubular reactor or riser reactor. The reaction is carried out under the following conditions: 650-900℃, 0.13-0.28 MPa, agent-to-oil ratio of 5-35, and contact time of 0.1-3.0 seconds. This method uses an aluminosilicate contact agent modified with alkaline or alkaline earth metal oxides. Under conditions not exceeding the tubular furnace pyrolysis temperature, it can achieve high yields of low-carbon olefins, with an ethylene yield of 17-27% and a total yield of ethylene, propylene, and butene of 30-40%.

[0005] CN1566267A discloses a method for the catalytic thermal cracking of petroleum hydrocarbons to produce ethylene and propylene. In this method, petroleum hydrocarbon feedstock is fed into a riser reactor and contacted with a hot five-membered ring high-silica zeolite catalyst. The catalytic thermal cracking reaction is carried out under the following conditions: reaction temperature 550-700℃, reaction pressure 150-400 kPa, catalyst-to-feedstock oil weight ratio 15-40:1, and steam-to-feedstock oil weight ratio 0.3-1:1. This method uses a phosphorus- and transition metal-containing five-membered ring high-silica zeolite catalyst with low hydrogen transfer activity and high ethylene selectivity. By increasing the reaction temperature, the yield of low-carbon olefins is increased, especially the yield of ethylene. While the above-mentioned existing technology can achieve a high ethylene yield, the formation of low-value products such as methane and coke is difficult to control. How to reduce the yield of methane and coke while increasing the yield of ethylene and propylene during the non-hydrogen-dependent catalytic conversion of petroleum hydrocarbon feedstocks to achieve higher ethylene and propylene production is a pressing technical problem that needs to be solved.

[0006] All patent and non-patent literature listed in this article is incorporated herein in its entirety for reference. Summary of the Invention

[0007] To address the above problems, this invention provides a catalytic cracking method for hydrocarbons to produce ethylene and propylene.

[0008] To address the aforementioned technical problems, this invention provides a catalytic cracking method for producing ethylene and propylene in excess of their original quantities, characterized by comprising the following steps:

[0009] S1. Hydrocarbon feedstock is brought into contact with a catalyst in a reactor system to react and obtain a reaction oil.

[0010] The reactor system includes at least a first reaction zone and a second reaction zone downstream of the first reaction zone. The hydrocarbon feedstock is introduced below or at the bottom of the first reaction zone. The average solid content of the catalyst in the first reaction zone is greater than 0.2, and the volume ratio of the region with a catalyst solid content greater than 0.2 in the first reaction zone is 0.2 to 0.7. The average solid content of the catalyst in the second reaction zone is less than 0.1.

[0011] S2. The reaction oil is subjected to gas-solid separation to obtain carbon deposit catalyst and oil gas;

[0012] S3. Regenerate the carbonized catalyst, and return the resulting regenerated catalyst to the reactor system for recycling.

[0013] S4. Optionally, the oil and gas are separated to obtain a product including ethylene and propylene.

[0014] To address the aforementioned technical problems, the present invention also provides a catalytic cracking reactor system for producing ethylene and propylene, characterized in that the reactor system includes at least a control unit, a first reaction zone, and a second reaction zone downstream of the first reaction zone; the first reaction zone has an inlet for hydrocarbon feedstock below or at its lower part, and the first reaction zone has an inlet for catalyst; the control unit is configured to set the average solid content of the catalyst in the first reaction zone to be greater than 0.2, and the volume percentage of the region in the first reaction zone with a catalyst solid content greater than 0.2 is 0.2 to 0.7; and to set the average solid content of the catalyst in the second reaction zone to be less than 0.1.

[0015] To address the aforementioned technical problems, the present invention also provides a catalytic cracking system for producing both ethylene and propylene, characterized in that it comprises the aforementioned catalytic cracking reactor system, a regenerator, and a settling tank.

[0016] The catalytic cracking reactor system is configured to allow hydrocarbon feedstocks to react with a catalyst to produce a reaction oil.

[0017] The settler is configured to allow gas-solid separation of the reactant to yield coked catalyst and oil gas containing ethylene and propylene.

[0018] The regenerator is configured to regenerate the coked catalyst from the settling tank and return the regenerated catalyst to the catalytic cracking reactor system.

[0019] In the catalytic cracking method of this invention, the reactor system is provided with a first reaction zone and a second reaction zone. In the initial stage of the reaction, a reaction zone with a high catalyst solids content is used, and the volume proportion of the high catalyst solids content area in the first reaction zone is controlled to increase the contact between hydrocarbon molecules and the active sites of the catalyst, significantly increasing the proportion of catalytic cracking reaction and reducing the degree of thermal cracking reaction. In the subsequent stage of the reaction, a reaction zone with a lower catalyst solids content is used to continue the catalytic cracking reaction while reducing the re-conversion of generated ethylene and propylene, and reducing hydrogen transfer and condensation reactions. This invention further increases the yield of ethylene and propylene while significantly reducing the yield of methane and coke, resulting in a substantial increase in the diene / (methane + coke) yield ratio. The method of this invention improves the yield of high-value ethylene and propylene, reduces the yield of low-value methane and coke, and improves the economic efficiency of the catalytic cracking method. Attached Figure Description

[0020] Figure 1 is a schematic diagram of one embodiment of the catalytic cracking system to which the catalytic cracking method for producing more ethylene and propylene of the present invention is applicable;

[0021] Figure 2 is a schematic diagram of a specific embodiment of the reactor system to which the catalytic cracking method for producing more ethylene and propylene of the present invention is applicable;

[0022] Figure 3 is a distribution curve of catalyst solid content as a function of reactor height in the reactor system in Example 1 of the present invention;

[0023] Figure 4 shows the distribution curve of catalyst solids content as a function of reactor height in the reactor system of Comparative Example 1.

[0024] Figure 5 is a distribution curve of catalyst solid content as a function of reactor height in the reactor system in Example 2 of the present invention;

[0025] Figure 6 is a distribution curve of catalyst solid content as a function of reactor height in the reactor system in Example 3 of the present invention.

[0026] Figure Labeling Explanation: 1. Reactor; 11. Feed Nozzle; 12. Pre-lift Steam Pipeline; 2. Regenerator; 21. Air Delivery Pipe; 22. Second Cyclone Separator; 23. Regenerated Flue Gas Delivery Pipe; 24. Regenerated Catalyst Delivery Pipe; 3. Stripper; 31. Stripping Steam Delivery Pipe; 32. Used Catalyst Delivery Pipe; 4. Settler; 41. First Cyclone Separator; 42. Oil and Gas Output Pipe; A. First Reaction Zone; B. Transition Zone; C. Second Reaction Zone Detailed Implementation

[0027] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. These descriptions will make the features and advantages of the present application clearer and more apparent. Exemplary embodiments are provided to make this disclosure thorough and to fully convey its scope to those skilled in the art. Numerous specific details, such as examples of specific compositions, components, apparatuses, and methods, are set forth to provide a full understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details are not required, and exemplary embodiments may be embodied in many different forms, none of which should be considered as limiting the scope of the present disclosure. In some exemplary embodiments, well-known methods, well-known apparatus structures, and well-known techniques are not described in detail.

[0028] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0029] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0030] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" as used herein are intended to include the plural forms as well. The terms "comprising," "including," "containing," and "having" are inclusive and thus describe the presence of the stated features, elements, compositions, steps, integers, operations, and / or components, but do not exclude the presence or inclusion of one or more other features, integers, steps, operations, elements, components, and / or sets thereof. Although the open-ended term "comprising" should be understood as a non-limiting term used to describe and claim the various embodiments described herein, in some respects it may instead be understood as a more restrictive and limiting term, such as "consisting of" or "essentially composed of." Thus, for any given embodiment describing a composition, material, component, element, feature, integer, operation, and / or process step, this disclosure also particularly includes embodiments consisting of or substantially consisting of such compositions, materials, components, elements, features, integers, operations, and / or process steps. In the case of "consisting of," the alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations, and / or process steps. In the case of "essentially composed of," any additional compositions, materials, components, elements, features, integers, operations, and / or process steps that substantially affect the essential and novel characteristics are excluded from such embodiments. However, any compositions, materials, components, elements, features, integers, operations, and / or process steps that do not substantially affect the essential and novel characteristics may be included in the embodiments.

[0031] Any methods, procedures, and operations described herein should not be construed as necessarily requiring them to be performed in the specific order discussed or shown, unless explicitly stated otherwise. It should also be understood that additional or alternative steps may be used unless otherwise stated.

[0032] Although the terms first, second, third, etc., may be used herein to describe various steps, elements, components, regions, layers, and / or sections, these steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise specified. These terms may be used only to distinguish one step, element, component, region, layer, or section from another. Unless clearly indicated by the context, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first step, element, component, region, layer, or section discussed below may be referred to as the second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0033] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0034] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0035] First aspect

[0036] A first aspect of the present invention provides a catalytic cracking method for producing ethylene and propylene, characterized by comprising the following steps:

[0037] S1. Hydrocarbon feedstock is brought into contact with a catalyst in a reactor system to react and obtain a reaction oil.

[0038] The reactor system includes at least a first reaction zone and a second reaction zone downstream of the first reaction zone. The hydrocarbon feedstock is introduced below or at the bottom of the first reaction zone. The average solid content of the catalyst in the first reaction zone is greater than 0.2, and the volume ratio of the region with a catalyst solid content greater than 0.2 in the first reaction zone is 0.2 to 0.7. The average solid content of the catalyst in the second reaction zone is less than 0.1.

[0039] S2. The reaction oil is subjected to gas-solid separation to obtain carbon deposit catalyst and oil gas;

[0040] S3. Regenerated carbonized catalyst, the resulting regenerated catalyst is returned to the reactor for recycling;

[0041] S4. Optionally, the oil and gas are separated to obtain a product including ethylene and propylene.

[0042] In the catalytic cracking method of this invention, the reactor system includes a first reaction zone with an average catalyst solids content greater than 0.2 and a second reaction zone downstream of the first reaction zone with an average catalyst solids content less than 0.1. The average catalyst solids content in the first reaction zone is greater than that in the second reaction zone. The feedstock and catalyst first enter the first reaction zone for contact reaction, yielding a partial reaction oil. This partial reaction oil continues to react in the second reaction zone, yielding another reaction oil. The first reaction zone is a high average catalyst solids content reaction zone, and the second reaction zone is a low average catalyst solids content reaction zone. Compared with existing technologies, the reactor simultaneously contains both high and low average catalyst solids content reaction zones. Using a high average catalyst solids content reaction zone in the initial stage of the reaction significantly increases the contact probability between hydrocarbon molecules and the active sites of the catalyst, significantly increasing the proportion of low-carbon olefins produced by the catalytic cracking reaction and reducing the degree of coke and methane production from the thermal cracking reaction. Simultaneously, using a low average catalyst solids content reaction zone at the end of the reaction reduces the re-conversion of generated ethylene and propylene, and reduces hydrogen transfer and condensation reactions. Therefore, the present invention can significantly reduce the yield of methane and coke while obtaining high yields of ethylene and propylene, thereby greatly increasing the yield ratio of diene / (methane + coke).

[0043] Through years of research and development, the inventors of this application unexpectedly discovered that by controlling the catalyst and raw materials to first pass through a reaction zone with a high average catalyst solids content after entering the reactor, and then enter a reaction zone with a low average catalyst solids content, the reaction oils in this system can be completely removed from the top of the reactor. Furthermore, by controlling the volume percentage of the region with a catalyst solids content greater than 0.2 in the first reaction zone as described above, the yields of ethylene and propylene can be further increased, while the yields of methane and coke can be reduced, thereby increasing the diene / (methane + coke) yield ratio.

[0044] In the context of this invention, a reaction oil refers to a mixture of hydrocarbon feedstock and catalyst or a dynamic reaction system of hydrocarbon feedstock and catalyst.

[0045] In the context of this invention, the term "carbon deposition catalyst" has its conventional meaning in the art. For example, a carbon deposition catalyst refers to a catalyst in which carbonaceous material is deposited on its surface or in its pores during catalytic cracking or catalytic pyrolysis.

[0046] In the context of this invention, "oil and gas" has its conventional meaning in the art. For example, "oil and gas" refers to a mixture of gaseous and liquid hydrocarbons produced by catalytic cracking of hydrocarbon feedstocks.

[0047] In one embodiment of the catalytic cracking method of the present invention, the average solid content of the catalyst in the first reaction zone is 0.25 to 0.5, for example, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or a range consisting of any two of these values, and the average solid content of the catalyst in the second reaction zone is less than 0.08, for example, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01 or a range consisting of any two of these values.

[0048] It should be noted that in the catalytic cracking method of this invention, the average solid content of the catalyst in the first reaction zone is further controlled to be 0.25–0.5%, ensuring that the contact between hydrocarbon molecules and the active sites of the catalyst is highly favorable for the hydrocarbon molecules to react in the direction of conversion into ethylene and propylene in the initial stage of the reaction. The average solid content of the catalyst in the second reaction zone is controlled to be less than 0.08%. Further regulation of the average solid content of the catalyst in the reaction zone with low average solid content at the end of the reaction effectively reduces the conversion of already generated ethylene and propylene, and further promotes the cracking of reaction intermediates into ethylene and propylene. Therefore, this invention can further improve the yield of ethylene and propylene while reducing the yield of methane and coke.

[0049] It should be noted that in the catalytic cracking method of this invention, the average solid content of the catalyst in the first reaction zone is further controlled to be 0.25-0.5%, ensuring that the contact between hydrocarbon molecules and the active center of the catalyst is highly favorable for the hydrocarbon molecules to react in the direction of conversion to ethylene and propylene in the initial stage of the reaction. The average solid content of the catalyst in the second reaction zone is controlled to be 0.04-0.08%. Further regulation of the average solid content of the catalyst in the reaction zone with low average solid content at the end of the reaction can effectively reduce the conversion of the already generated ethylene and propylene, and further promote the cracking of the reaction intermediates into ethylene and propylene. Therefore, the above-mentioned preferred combination of the average solid content range of the first reaction zone and the average solid content range of the second reaction zone can further improve the yield of ethylene and propylene, while further reducing the yield of methane and coke.

[0050] In one embodiment of the catalytic cracking method of the present invention, the first reaction zone and the second reaction zone are arranged coaxially or non-coaxially, preferably coaxially.

[0051] With different shaft configurations, the first reaction zone can be located in the regenerated catalyst channel section (the regenerated catalyst channel from the regenerator to the catalytic cracking reactor), forming a separate reactor. The catalyst can be added at the top of this reactor, while steam and feedstock are added at the bottom or lower part. This countercurrent contact helps improve the contact between the catalyst active sites and the feedstock, accelerating the reaction rate. In this case, a portion of the reactant leaving the first reactor enters the second reaction zone and continues to react there, producing more reactant.

[0052] In one embodiment of the catalytic cracking method of the present invention, the hydrocarbon feedstock is a preheated hydrocarbon feedstock. The heat source for preheating can be electric heating, fuel heating, steam, hot regenerator flue gas, etc., wherein the regenerator flue gas used is heated by waste heat within the system to effectively utilize the residual heat of the catalytic cracking system.

[0053] In one embodiment of the catalytic cracking method of the present invention, the hydrocarbon feedstock is introduced together with a medium below or in the lower part of the first reaction zone, wherein the medium is selected from water vapor, nitrogen and dry gas, preferably water vapor.

[0054] In the context of this invention, "below" the first reaction zone means below the inlet of the first reaction zone. "Lower portion" of the first reaction zone means the area from the inlet of the first reaction zone to no more than 10% of the height of the first reaction zone.

[0055] In one embodiment of the catalytic cracking method of the present invention, the raw material and water vapor can be introduced from below or at the bottom of the reactor system (first reaction zone), and the catalyst can be introduced from below or at the bottom of the reactor system (first reaction zone). The raw material and the catalyst ascend and pass through the first reaction zone and the second reaction zone in succession. During this process, the catalyst and the raw material come into contact and a catalytic cracking reaction occurs.

[0056] In one embodiment of the catalytic cracking method of the present invention, the feedstock and steam can be introduced from below or at the bottom of the reactor system (first reaction zone), and the catalyst can be introduced from above the reactor system (first reaction zone). The upward-flowing feedstock and the downward-flowing catalyst come into countercurrent contact to undergo a catalytic cracking reaction. Subsequently, the feedstock and catalyst leave the first reaction zone together and then flow upward into the second reaction zone.

[0057] In one embodiment of the catalytic cracking method of the present invention, the first reaction zone and the second reaction zone above the first reaction zone are coaxially arranged to form a reactor. The average solid content of the catalyst in the first reaction zone is greater than that in the second reaction zone. The feedstock and catalyst first rise into the first reaction zone and then continue to rise into the second reaction zone. The first reaction zone is a reaction zone with a high average solid content of catalyst, and the second reaction zone is a reaction zone with a low average solid content of catalyst. The coaxial arrangement of the first reaction zone and the second reaction zone above the first reaction zone helps the hydrocarbon feedstock to leave the reaction zone quickly and reduces side reactions.

[0058] In one embodiment of the catalytic cracking method of the present invention, the first reaction zone and the second reaction zone above the first reaction zone are coaxially arranged to form a reactor. The catalyst solid content in the reactor exhibits a gentle gradient distribution characteristic that gradually decreases from bottom to top along the axial direction. Wherein, "the catalyst solid content exhibits a gentle gradient distribution characteristic that gradually decreases from bottom to top along the axial direction" means that in the curve of catalyst solid content G versus height h from the bottom of the reactor as a percentage of the total height H of the reactor, within the range of h / H of 10% to 90%, the difference ΔG of catalyst solid content G at any two points where h / H differs by 10% is not greater than 0.2.

[0059] The volume percentage of the region in the first reaction zone with a catalyst solid content greater than 0.2 is greater than or equal to 0.1, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or any two of these values, and the volume percentage is preferably 0.2 to 0.7.

[0060] It should be noted that the region in the first reaction zone where the catalyst solid content is greater than 0.2 refers to the area from the bottom of the first reaction zone upwards to the position where the catalyst solid content is 0.2; when the first reaction zone is a constant diameter reaction zone, the volume ratio is the same as the height ratio.

[0061] It should be noted that by controlling the reactor structure, such as the height-to-diameter ratio of the first reaction zone and the top / bottom cross-sectional diameter ratio of the second reaction zone, as well as the reaction conditions, such as the catalyst-to-oil mass ratio, water-to-oil mass ratio, and reaction time, the catalyst solid content in the first and second reaction zones can be regulated. This includes controlling the average catalyst solid content so that the catalyst solid content in the reactor exhibits a gentle gradient distribution characteristic that gradually decreases from bottom to top along the axial direction, as described above. This can further improve the yield of ethylene and propylene, while reducing the yield of methane and coke, and increasing the diene / (methane + coke) yield ratio.

[0062] In another embodiment of the catalytic cracking method of the present invention, the first reaction zone and the second reaction zone located above the first reaction zone are coaxially arranged to form a reactor. The proportion of the first reaction zone in the total height of the reactor is 0.1 to 0.4, for example, 0.1, 0.2, 0.3, 0.4, or any two of these values. The proportion of the second reaction zone in the total height of the reactor is 0.6 to 0.9, for example, 0.6, 0.7, 0.8, 0.9, or any two of these values. Preferably, the reactor consists only of the first reaction zone and the second reaction zone. In this case, the sum of the first and second reaction zones in the total height of the reactor is 1.

[0063] Optionally, the reactor further includes a transition zone connected between the first reaction zone and the second reaction zone;

[0064] The first reaction zone accounts for 0.1 to 0.4% of the total height of the reactor, the second reaction zone accounts for 0.5 to 0.8% of the total height of the reactor, and the remaining height is the transition zone. Preferably, the reactor consists only of the first reaction zone, the transition zone, and the second reaction zone. In this case, the sum of the first reaction zone, the transition zone, and the second reaction zone in the total height of the reactor is 1.

[0065] It should be noted that in this embodiment, the transition zone connects the first reaction zone and the second reaction zone. The reactor, from bottom to top, includes the first reaction zone, the transition zone, and the second reaction zone, and the sum of the height ratios of the first reaction zone, the transition zone, and the second reaction zone is 1. By setting a transition zone between the first reaction zone and the second reaction zone, and controlling the proportion of the three reaction zones in the total height of the reactor as described above, the catalytic cracking reaction can be smoothly directed towards producing more ethylene and propylene.

[0066] In another embodiment of the catalytic cracking method described above in this invention, the radial cross-section of the transition zone is circular, and the longitudinal cross-section along the axis is a symmetrical straight line or curve with the axis as the axis of symmetry.

[0067] It should be noted that the axial direction can be perpendicular to the radial direction, the radial cross section can be a horizontal section, and the axial longitudinal section can be a vertical section. In the preferred embodiment, the axial longitudinal section passes through the central axis of the reaction zone.

[0068] In one embodiment of the catalytic cracking method of the present invention, the first reaction zone is a constant diameter reaction zone with a height-to-diameter ratio of 0.5 to 20:1, for example, 0.5:1, 1:1, 1.5:1, 1.5:1, 2:1, 2.5:1, 2.5:1, 3:1, 3.5:1, 3.5:1, 4:1, 4.5:1, 4.5:1, 5:1, 5.5:1, 5.5:1, 6:1, 6.5:1, 6.5:1, 7:1, 7.5:1, 7.5:1, 8:1, 8.5:1, 8.5:1, 9:1, 9.5:1, 9.5:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1 or a range consisting of any two of these ratios, preferably 1 to 10:1;

[0069] The second reaction zone is a narrowing reaction zone, with circular cross-sections at both the top and bottom ends, and the diameter ratio of the top and bottom cross-sections is 0.1 to 0.5:1, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, or any two of these ratios.

[0070] In the context of this invention, the height-to-diameter ratio refers to the ratio between the height of the reaction zone and its diameter (equivalent diameter). In the context of this invention, the diameter refers to the inner diameter of the reactor.

[0071] In a preferred embodiment, the second reaction zone is a uniformly narrowed reaction zone with an axial longitudinal section that is an isosceles trapezoid. The inclination angle of the sides of the isosceles trapezoid is 5-85°, for example, 5°, 10°, 20°, 30°, 40°, 45°, 50°, 60°, 70°, 80°, 85°, or a range consisting of any two of these ratios, preferably 45°-85°. It should be noted that a larger inclination angle (closer to 90°) is beneficial for the catalyst solids content in the reactor to exhibit a gentle gradient distribution characteristic that gradually decreases from bottom to top along the axial direction.

[0072] It should be noted that by controlling the shape and size parameters of the first reaction zone, transition zone, and second reaction zone as described above, the catalyst solid content and the average catalyst solid content can be regulated. This allows for better synergistic effects between the high catalyst average solid content reaction zone, which regulates the catalyst active center and feedstock contact, and the low catalyst average solid content reaction zone, which reduces the conversion of ethylene and propylene. This further increases the yield of ethylene and propylene while reducing the yield of methane and coke, thereby significantly improving the yield ratio of diene / (methane + coke).

[0073] In one embodiment of the catalytic cracking method of the present invention, the first reaction zone is one or a combination of two of the constant diameter fluidized bed and the variable diameter fluidized bed;

[0074] The second reaction zone is one or a combination of two of the following: a constant diameter riser and a variable diameter riser.

[0075] It should be noted that the first reaction zone can be a fluidized bed with constant diameter, or a fluidized bed with variable diameter, or a combination of fluidized beds with constant diameter and variable diameter. The second reaction zone can be a riser with constant diameter, or a riser with variable diameter, or a combination of risers with constant diameter and variable diameter.

[0076] In one embodiment of the catalytic cracking method of the present invention, the reaction temperature of the first reaction zone is 500-750°C, preferably 600-700°C.

[0077] In one embodiment of the catalytic cracking method of the present invention, the reaction temperature of the second reaction zone is 480-730°C, preferably 580-680°C.

[0078] In one embodiment of the catalytic cracking method of the present invention, the reaction temperature of the second reaction zone is 10-30°C lower than that of the first reaction zone, preferably 15-25°C lower. By setting the reaction temperature of the second reaction zone to be lower than that of the first reaction zone by the above range, it is advantageous to further reduce the yield of methane and coke.

[0079] Alternatively, in one embodiment of the catalytic cracking method of the present invention, the reaction temperature of the second reaction zone is 10-30°C higher than that of the first reaction zone, preferably 15-25°C higher. By setting the reaction temperature of the second reaction zone to be higher than that of the first reaction zone by the above range, it is helpful to further increase the yield of ethylene and propylene; however, the cost is increased methane and coke production.

[0080] In one embodiment of the catalytic cracking method of the present invention, the reaction temperature of the first reaction zone is 500-750°C, the reaction pressure is 0.10-0.20 MPa, the agent-to-oil mass ratio is 5-50:1, the water-to-oil mass ratio is 0.1-1.5:1, and the reaction time is 0.1-20 seconds.

[0081] Preferably, the reaction temperature in the first reaction zone is 600–700°C, the reaction pressure is 0.11–0.14 MPa, the agent-to-oil mass ratio is 10–30:1, the water-to-oil mass ratio is 0.3–1:1, and the reaction time is 0.5–10 seconds.

[0082] In the context of this invention, the catalyst-to-oil mass ratio refers to the mass ratio of the catalyst to the hydrocarbon feedstock. In the context of this invention, the water-to-oil mass ratio refers to the mass ratio of water vapor to the hydrocarbon feedstock.

[0083] More preferably, when the water-oil mass ratio in the first reaction zone is 0.6 to 1:1, the yield ratio of diene / (methane + coke) can be further improved.

[0084] More preferably, when the reaction time of the first reaction zone is 0.1-1:1 with the reaction time of the second reaction zone, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or a range consisting of any two of these ratios, the yield ratio of diene / (methane + coke) can be further improved. It should be noted that diene here refers to ethylene + propylene.

[0085] In one embodiment of the catalytic cracking method of the present invention, the reaction temperature of the second reaction zone is 480-730°C and the reaction time is 0.1-20 seconds.

[0086] Preferably, the reaction temperature in the second reaction zone is 580–680°C, and the reaction time is 1–10 seconds.

[0087] According to an advantageous embodiment, the temperature of the second reaction zone is 10-50°C lower than that of the first reaction zone, preferably 10-30°C lower. Surprisingly, it has been found that by setting the temperature of the second reaction zone below that of the first reaction zone by a specific range, lower methane and coke yields are advantageously achieved.

[0088] It should be noted that by controlling the reaction conditions of the first and second reaction zones as described above, various raw materials such as petroleum hydrocarbons can be catalytically cracked according to the method of this invention, which can better control the catalyst solid content and obtain a high diene / (methane + coke) yield ratio.

[0089] In one embodiment of the catalytic cracking method of the present invention, the catalyst comprises 10-80% matrix, 10-80% binder, and 10-80% molecular sieve by weight of the total catalyst. The total mass of the catalyst is the dry weight of the catalyst.

[0090] In a preferred embodiment, the matrix is ​​selected from clay, and the clay is selected from one or more of kaolin, hydrous kaolin, sepiolite, attapulgite, montmorillonite, and leucite.

[0091] In a preferred embodiment, the binder is selected from inorganic oxides, which are one or more selected from alumina, silicon oxide, amorphous aluminum silicate, and aluminum phosphate sol.

[0092] In a preferred embodiment, the molecular sieve is one or more selected from ZSM molecular sieve, β molecular sieve, and Y molecular sieve.

[0093] In a preferred embodiment, the molecular sieve is a molecular sieve modified with non-metallic elements and / or metallic elements, wherein the non-metallic elements include phosphorus, and the metallic elements are one or more selected from iron, cobalt, nickel, magnesium, calcium, and rare earth elements. Rare earth elements include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

[0094] It should be noted that the matrix can be selected from the above-mentioned kaolin, hydrous kaolin, sepiolite, etc., the binder can be selected from inorganic oxides such as alumina and silicon dioxide, and the molecular sieve can be selected from ZSM molecular sieve, β molecular sieve, Y molecular sieve and their modified molecular sieves. All of these can be well applied to the catalytic cracking method of the present invention and achieve the production of more ethylene and propylene.

[0095] In one embodiment of the catalytic cracking method of the present invention, the catalyst comprises 15-70% clay, 15-70% inorganic oxides and 15-70% molecular sieve by weight of the total catalyst.

[0096] The clay is kaolin and / or hydrous kaolin, the inorganic oxide is SiO2 and / or Al2O3, the molecular sieve is one or more of ZSM molecular sieve, β molecular sieve, and Y molecular sieve modified with non-metallic elements and / or metallic elements, the non-metallic elements include phosphorus, and the metallic elements are one or more selected from iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

[0097] In another embodiment of the catalytic cracking method of the present invention, the raw material is selected from one or more of petroleum hydrocarbons, animal and vegetable oils, synthetic oils, and biomass, wherein the petroleum hydrocarbons have a carbon number greater than or equal to 4.

[0098] It should be noted that the above-mentioned raw materials, after being processed by the catalytic cracking method of the present invention, which involves contacting the reaction zone with a high average solid content of the catalyst first and then the reaction zone with a low average solid content of the catalyst, can achieve the production of more ethylene and propylene, and reduce the generation of methane and coke.

[0099] Second aspect

[0100] A second aspect of the present invention provides a catalytic cracking reactor system for producing ethylene and propylene, characterized in that the reactor system includes at least a control unit, a first reaction zone, and a second reaction zone downstream of the first reaction zone, wherein the first reaction zone has an inlet for hydrocarbon feedstock below or at its lower part and has an inlet for catalyst, and the control unit is configured to set the average solid content of the catalyst in the first reaction zone to be greater than 0.2 and the volume percentage of the region in the first reaction zone with a catalyst solid content greater than 0.2 is 0.2 to 0.7, and to set the average solid content of the catalyst in the second reaction zone to be less than 0.1.

[0101] It is worth noting that the first reaction zone is equipped with detection units at least at the bottom and top for detecting axial pressure and catalyst particle density. The second reaction zone is also equipped with detection units at least at the bottom and top for detecting axial pressure and catalyst particle density. The detection units can transmit the obtained detection results to the control unit. Based on the above data, the average solids content of the catalyst in the first and second reaction zones is calculated. The average solids content is affected by the structure of the reactor system, such as the height-to-diameter ratio of the first reaction zone and the top / bottom cross-sectional diameter ratio of the second reaction zone. During reactor operation, when the average solids content of the catalyst in either the first or second reaction zone deviates from the aforementioned set value range, it can be controlled by adjusting reaction conditions such as the catalyst-to-oil mass ratio, water-to-oil mass ratio, and reaction time through the control unit. Accordingly, the control unit has control circuitry for regulating, preferably automatically regulating, for example, the flow rate of the hydrocarbon feedstock and the flow rate of water vapor. This regulation can be implemented separately, for example, through control valves.

[0102] In one embodiment of the second aspect, the first reaction zone and the second reaction zone are coaxially arranged to form a reactor.

[0103] In one embodiment of the second aspect, the first reaction zone accounts for 0.1 to 0.4% of the total height of the reactor, and the second reaction zone accounts for 0.6 to 0.9% of the total height of the reactor.

[0104] Optionally, the reactor further includes a transition zone disposed between the first reaction zone and the second reaction zone; the first reaction zone accounts for 0.1 to 0.4% of the total height of the reactor, the second reaction zone accounts for 0.5 to 0.8% of the total height of the reactor, and the remaining height is the transition zone.

[0105] In one embodiment according to the second aspect, the radial cross-section of the transition zone is circular, and the longitudinal cross-section along the axis is a symmetrical straight line or curve with the axis as the axis of symmetry.

[0106] In one embodiment according to the second aspect, the first reaction zone is a constant diameter reaction zone with a height-to-diameter ratio of 0.5 to 20:1, preferably 1 to 10:1;

[0107] The second reaction zone is a diameter-reducing reaction zone, with circular cross-sections at both the top and bottom, and the diameter ratio of the top and bottom cross-sections is 0.1 to 0.5:1.

[0108] In one embodiment of the second aspect, the first reaction zone is one or a combination of two of a constant-diameter fluidized bed and a variable-diameter fluidized bed;

[0109] The second reaction zone is one or a combination of two of the following: a constant diameter riser and a variable diameter riser.

[0110] It should be understood that the disclosures regarding the reactor system in the foregoing description of the catalytic cracking method also apply to the second aspect.

[0111] Third aspect

[0112] A third aspect of the present invention provides a catalytic cracking system for producing ethylene and propylene in large quantities, characterized in that it comprises the above-described catalytic cracking reactor system, a regenerator, and a settling tank.

[0113] The catalytic cracking reactor system is configured to allow hydrocarbon feedstocks to contact with a catalyst to produce a reactive oil.

[0114] The settler is configured to allow gas-solid separation of the reactant to yield coked catalyst and oil gas containing ethylene and propylene.

[0115] The regenerator is configured to regenerate the coked catalyst from the settling tank and return the regenerated catalyst to the catalytic cracking reactor system.

[0116] The following describes in detail, with reference to Figures 1 and 2, a catalytic cracking reaction system suitable for the above-mentioned catalytic cracking method for producing ethylene and propylene from hydrocarbons, comprising:

[0117] Reactor 1, regenerator 2, stripper 3, and settler 4;

[0118] Reactor 1 is provided with a first reaction zone A and a second reaction zone C from bottom to top. The average solid content of the catalyst in the first reaction zone A is greater than 0.2, and the average solid content of the catalyst in the second reaction zone C is less than 0.1.

[0119] A transition zone B may be arbitrarily provided between the first reaction zone A and the second reaction zone C;

[0120] The reactor 1 is provided with a raw material feed nozzle 11 and a catalyst inlet at its lower part or below; the raw material feed nozzle 11 and the catalyst inlet may be located at the lower part or below the first reaction zone A.

[0121] A pre-lift steam pipeline 12 may be installed below reactor 1;

[0122] The settling tank 4 is equipped with a first cyclone separator 41. The oil outlet of the reactor 1 is connected to the inlet of the first cyclone separator 41 via an oil outlet pipe. The top of the settling tank 4 is equipped with an oil and gas outlet pipe 42.

[0123] The lower end of the settling tank 4 is equipped with a stripper 3, which is equipped with a stripping steam conveying pipe 31. The catalyst outlet of the stripper 3 is connected to the catalyst inlet of the regenerator 2 via a catalyst delivery pipe 32.

[0124] The regenerator 2 is equipped with an air delivery pipe 21, a second cyclone separator 22 and a regenerated flue gas delivery pipe 23. The catalyst outlet of the regenerator 2 is connected to the catalyst inlet of the reactor 1 via the regenerated catalyst delivery pipe 24.

[0125] As shown in Figure 1, the hot regenerated catalyst is introduced into the bottom of reactor 1 through the regenerated catalyst delivery pipe 24 and flows upward under the action of the pre-lifting medium. Raw materials and steam are sprayed into the bottom of reactor 1 through the raw material feed nozzle 11, contacting the regenerated catalyst and undergoing catalytic cracking reaction in reactor 1. After the reaction, the oil is separated from the catalyst in the settling tank 4. The carbonized catalyst enters the stripper 3, where steam removes the adsorbed oil and gas products from the catalyst, and then it is sent to the regenerator 2 for regeneration via the spent catalyst delivery pipe 32. The regenerated catalyst is returned to reactor 1 for reuse. The separated oil and gas enter the subsequent separation system (not shown in Figure 1) through the oil and gas output pipe 42, where preliminary separation yields dry gas, liquefied petroleum gas, gasoline, diesel, and heavy oil, and further separation yields products such as ethylene and propylene. Reactor 1 includes two reaction zones (A and C from bottom to top) and a transition zone (B).

[0126] Example

[0127] The present invention will be further described in detail below through examples, but these examples are not intended to limit the invention. In the following examples, unless otherwise specified, the experimental instruments and raw materials involved are all commercially available products.

[0128] Unless otherwise specified, the raw materials used in the examples and comparative examples are atmospheric residue oils, the properties of which are shown in Table 1, and the properties of the catalysts used are shown in Table 2.

[0129] Table 1

[0130] Table 2

[0131] The molecular sieve, matrix, and binder of the catalyst were purchased from Sinopec Catalyst Qilu Branch. The catalyst consists of 35% phosphorus and iron-modified ZSM-5 molecular sieve, 42% kaolin, and 23% SiO2 binder. The phosphorus modifier is ammonium dihydrogen phosphate, and the iron modifier is ferric nitrate. The molecular sieve, matrix, and binder are mixed and slurried, then sequentially spray-dried, washed, filtered, and dried. Before use, the catalyst is aged at 800℃ with 100% steam for 17 hours.

[0132] In the following examples or comparative examples, the catalyst solids content was calculated as follows:

[0133] Catalyst solid content = Pressure difference between two points along the axial direction of the reactor as measured by the differential pressure gauge ÷ Distance between the two points along the axial direction ÷ Catalyst particle density;

[0134] The unit for pressure difference is kg / m³. 2 The unit of distance between two points along the axis is meters (m), and the unit of catalyst particle density is kg / m³. 3 The two points along the axial direction are any two points along the axial direction of the reactor.

[0135] For the average solid content of the catalyst, the two selected axial points are the bottom and top of the reaction zone, respectively. The distance between the two points represents the height of the reaction zone, and the pressure difference between them represents the pressure difference between the top and bottom of the reaction zone.

[0136] In the following embodiments:

[0137] The constant-diameter reaction zone (first reaction zone) is a constant-diameter fluidized bed, and the reduced-diameter reaction zone (second reaction zone) is a variable-diameter riser. The top and bottom cross-sections of the reduced-diameter reaction zone are both circular. The transition zone has a circular radial cross-section and a symmetrical straight line along the axis.

[0138] Example 1

[0139] The experiment was conducted in the catalytic cracking unit shown in Figure 1. The feedstock was atmospheric residue oil, and the catalyst was a heavy oil cracking catalyst with the properties listed in Table 2. During the experiment, hot regenerated catalyst was introduced to the bottom of the reactor. Preheated atmospheric residue oil and water vapor were injected into the bottom of the reactor through the feed nozzle, contacting the regenerated catalyst to carry out the catalytic cracking reaction in the reactor. As shown in Figure 2, the reactor includes a constant-diameter reaction zone (first reaction zone A), a narrow-diameter reaction zone (second reaction zone C), and a transition zone B. The constant-diameter reaction zone occupies 0.3% of the reactor height (composed of the first reaction zone A, the transition zone, and the second reaction zone C), has a height-to-diameter ratio of 6, a volume percentage of solids greater than 0.2% of 0.5%, an average solids content of 0.3%, a reaction temperature of 650℃, a reaction time of 1 second, a catalyst-to-oil mass ratio of 15, a water-to-oil mass ratio of 50%, and a reaction pressure of 0.12 MPa. The narrow-diameter reaction zone accounts for 0.65% of the reactor height, with an average solids content of 0.06%, a reaction temperature of 630℃, a reaction time of 1 second, and a top / bottom cross-sectional diameter ratio of 0.4. The volume percentage with a solids content greater than 0.2 represents the volume percentage of the equal-diameter reaction zone (first reaction zone) with a solids content greater than 0.2. The reacted oil is introduced into an oil separation system, and the separated reaction oil and gas enter the subsequent product separation system. The separated catalyst is stripped and then introduced into a regenerator for coke burn-off regeneration. The regenerated catalyst is returned to the reactor for recycling. The unit uses electric heating to maintain the temperature of the reaction and regeneration systems. The main operating conditions and results are listed in Table 3. The distribution curve of catalyst solids content with reactor height is shown in Figure 3 (the horizontal axis represents the proportion of the distance h from any position in the reactor to the bottom of the reactor in the total reactor height H).

[0140] Comparative Example 1

[0141] The raw materials, catalysts, and main implementation steps used are the same as in Example 1. The difference is that the reactor only includes one constant-diameter reaction zone, excluding the narrow-diameter reaction zone and the transition zone. That is, the constant-diameter reaction zone accounts for 1 / 2 of the reactor height (composed of the first reaction zone A, the transition zone, and the second reaction zone C), with an average solid content of 0.3% and a reaction time of 2 seconds. The main operating conditions and results are listed in Table 3. The distribution curve of catalyst solid content with reactor height is shown in Figure 4.

[0142] Comparative Example 2

[0143] The raw materials and catalysts used, as well as the main implementation steps, are the same as in Example 1. The difference lies in the shape of the reactor and the average solid content of the catalyst in the second reaction zone. Specifically, the diameter ratio of the top to the bottom cross-section of the narrowed reaction zone is 0.7, and the average solid content is 0.12. The main operating conditions and results are listed in Table 3.

[0144] Comparative Example 3

[0145] The raw materials and catalysts used, as well as the main implementation steps, are the same as in Example 1. The differences are that the catalyst-to-oil ratio is different, and the average solid content of the catalyst in the first reaction zone is different. Specifically, the catalyst-to-oil ratio in the first reaction zone is 10, the average solid content of the catalyst in the first reaction zone is 0.15, and the volume percentage of solids with a content greater than 0.2% is 0.06%. The main operating conditions and results are listed in Table 3.

[0146] Example 2

[0147] The raw materials, catalysts, and main implementation steps used are the same as in Example 1, except that the reactor shape is different, and the reaction times of the constant-diameter reaction zone and the narrow-diameter reaction zone are different. Specifically, the constant-diameter reaction zone occupies 0.25% of the reactor height (composed of the first reaction zone A, the transition zone, and the second reaction zone C), has a height-to-diameter ratio of 4, a volume percentage of solids greater than 0.2% of 0.3%, an average solid content of 0.25%, a reaction time of 0.8 seconds, and a water-to-oil mass ratio of 80%. The narrow-diameter reaction zone occupies 0.7% of the reactor height, has an average solid content of 0.05%, a reaction time of 3 seconds, and a top / bottom cross-sectional diameter ratio of 0.2. The main operating conditions and results are listed in Table 3. The distribution curve of catalyst solid content with reactor height is shown in Figure 5.

[0148] Example 3

[0149] The raw materials and catalysts used, as well as the main implementation steps, are the same as in Example 1. The difference lies in the shape of the reactor and the reaction times of the constant-diameter reaction zone and the narrow-diameter reaction zone. Specifically, the constant-diameter reaction zone occupies 0.4% of the reactor height (composed of the first reaction zone A, the transition zone, and the second reaction zone C), has a height-to-diameter ratio of 15, a volume percentage of solids greater than 0.2% of 0.09%, an average solid content of 0.21%, and a reaction time of 1.5 seconds; the narrow-diameter reaction zone occupies 0.55% of the reactor height, has an average solid content of 0.06%, and a reaction time of 2 seconds. The main operating conditions and results are listed in Table 3. The distribution curve of catalyst solid content with reactor height is shown in Figure 6.

[0150] Example 4

[0151] The raw materials and catalysts used, as well as the main implementation steps, are the same as in Example 1, except that the shape of the reactor is different; specifically, the equal-diameter reaction zone accounts for 0.15% of the reactor height, and the narrow-diameter reaction zone accounts for 0.8% of the reactor height. The main operating conditions and results are listed in Table 3.

[0152] Example 5

[0153] The catalyst and main implementation steps used were the same as in Example 1, except that the feedstock used was straight-run naphtha with a density of 0.756 g / cm³, an initial boiling point of 31°C, a final boiling point of 209°C, an alkane content of 62.16%, a cycloalkanes content of 32.24%, and an aromatics content of 5.60%. The reaction temperature in the first reactor was 670°C, and the reaction temperature in the second reactor was 650°C. The main operating conditions and results are listed in Table 3.

[0154] Table 3

[0155] As can be seen from the data in Table 3, the hydrocarbon catalytic cracking method provided by this invention has the effect of significantly improving the yield of ethylene and propylene and increasing the diene / (methane + coke) ratio.

[0156] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0157] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0158] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. Catalytic cracking process for the maximization of ethylene and propylene, characterized in that, Includes the following steps: S1. Hydrocarbon feedstock is brought into contact with a catalyst in a reactor system to react and obtain a reaction oil. The reactor system includes at least a first reaction zone and a second reaction zone downstream of the first reaction zone. The hydrocarbon feedstock is introduced below or at the bottom of the first reaction zone. The average solid content of the catalyst in the first reaction zone is greater than 0.2, and the volume ratio of the region with a catalyst solid content greater than 0.2 in the first reaction zone is 0.2 to 0.

7. The average solid content of the catalyst in the second reaction zone is less than 0.

1. S2. The reaction oil is subjected to gas-solid separation to obtain carbon deposit catalyst and oil gas; S3. Regenerate the carbonized catalyst, and return the resulting regenerated catalyst to the reactor system for recycling. S4. Optionally, the oil and gas are separated to obtain a product including ethylene and propylene.

2. The catalytic cracking process of claim 1 wherein, The average solid content of the catalyst in the first reaction zone is 0.25 to 0.5, and / or the average solid content of the catalyst in the second reaction zone is less than 0.

08.

3. The catalytic cracking process according to claim 1 or 2, characterized in that, The first reaction zone and the second reaction zone may be arranged coaxially or non-coaxially, preferably coaxially.

4. The catalytic cracking process according to any one of claims 1 to 3, characterized in that, The catalytic cracking method has at least one of the following characteristics: The hydrocarbon raw material is a preheated hydrocarbon raw material. The hydrocarbon feedstock is introduced together with a medium below or in the lower part of the first reaction zone. The medium is selected from water vapor, nitrogen, and dry gas, preferably water vapor. The carbonized catalyst is stripped and then regenerated in a regenerator.

5. The catalytic cracking process according to any one of claims 1 to 4, characterized in that, The catalytic cracking method has at least one of the following characteristics: The first reaction zone and the second reaction zone above the first reaction zone are coaxially arranged to form a reactor. The catalyst solid content in the reactor exhibits a gentle gradient distribution characteristic that gradually decreases from bottom to top along the axial direction. Herein, "the catalyst solid content exhibits a gentle gradient distribution characteristic that gradually decreases from bottom to top along the axial direction" means that in the curve of catalyst solid content G versus height h from the bottom of the reactor as a percentage of the total height H of the reactor, within the range of h / H of 10% to 90%, the difference ΔG between any two points where h / H differs by 10% is not greater than 0.

2.

6. The catalytic cracking method according to any one of claims 1-5, characterized in that, The first reaction zone and the second reaction zone located above the first reaction zone are coaxially arranged to form a reactor. The first reaction zone accounts for 0.1 to 0.4% of the total height of the reactor, and the second reaction zone accounts for 0.6 to 0.9% of the total height of the reactor. Optionally, the reactor further includes a transition zone disposed between the first reaction zone and the second reaction zone; the first reaction zone accounts for 0.1 to 0.4% of the total height of the reactor, the second reaction zone accounts for 0.5 to 0.8% of the total height of the reactor, and the remaining height is the transition zone.

7. The catalytic cracking process of claim 6 wherein, The radial cross-section of the transition zone is circular, and the longitudinal cross-section along the axis is a symmetrical straight line or curve with the axis as the axis of symmetry.

8. The catalytic cracking process according to any one of claims 1 to 7, characterized in that, The first reaction zone is a constant-diameter reaction zone with a height-to-diameter ratio of 0.5 to 20:1, preferably 1 to 10:1; and / or The second reaction zone is a diameter-reducing reaction zone, with circular cross-sections at both the top and bottom, and the diameter ratio of the top and bottom cross-sections is 0.1 to 0.5:

1.

9. The catalytic cracking process according to any one of claims 1 to 7, characterized in that, The first reaction zone is one or a combination of two of the following: a constant-diameter fluidized bed and a variable-diameter fluidized bed; and / or The second reaction zone is one or a combination of two of the following: a constant diameter riser and a variable diameter riser.

10. The catalytic cracking process according to any one of claims 1 to 9, characterized in that, The reaction temperature in the first reaction zone is 500–750°C, the reaction pressure is 0.10–0.20 MPa, the agent-to-oil mass ratio is 5–50:1, the hydrocarbon raw material is introduced together with water vapor below or at the bottom of the first reaction zone, the water-to-oil mass ratio is 0.1–1:1, and the reaction time is 0.1–20 seconds. Preferably, the reaction temperature of the first reaction zone is 600-700℃, the reaction pressure is 0.11-0.14MPa, the agent-to-oil mass ratio is 10-30:1, the hydrocarbon raw material is introduced together with water vapor below or at the bottom of the first reaction zone, the water-to-oil mass ratio is 0.3-0.8:1, and the reaction time is 0.5-10 seconds.

11. The catalytic cracking process according to any one of claims 1 to 10, characterized in that, The reaction temperature in the second reaction zone is 480–730°C, and the reaction time is 0.1–20 seconds. Preferably, the reaction temperature in the second reaction zone is 580–680°C, and the reaction time is 1–10 seconds.

12. The catalytic cracking process according to any one of claims 1 to 11, characterized in that, The raw materials and catalyst first enter the first reaction zone for contact reaction to obtain a partial reaction oil, which then enters the second reaction zone for further reaction to obtain the final reaction oil.

13. The catalytic cracking process according to any one of claims 1 to 12, characterized in that, The catalyst has at least one of the following characteristics: The catalyst comprises 10-80% matrix, 10-80% binder and 10-80% molecular sieve by weight of total catalyst. The matrix is ​​selected from clay, and the clay is selected from one or more of kaolin, hydrous kaolin, sepiolite, attapulgite, montmorillonite, and pyroxene. The binder is selected from inorganic oxides, and the inorganic oxides are one or more selected from alumina, silicon oxide, amorphous aluminum silicate, and aluminum phosphate sol; The molecular sieve is selected from one or more of ZSM molecular sieves, β molecular sieves, and Y molecular sieves. Preferably, the molecular sieve is a molecular sieve modified with non-metallic elements and / or metallic elements, wherein the non-metallic elements include phosphorus, and the metallic elements are one or more selected from iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

14. The catalytic cracking process according to any one of claims 1 to 13, characterized in that, The catalyst has at least one of the following characteristics: The catalyst comprises 15-70% clay, 15-70% inorganic oxides and 15-70% molecular sieve by total mass of the catalyst; The clay is kaolin and / or water-rich kaolin. The inorganic oxide is SiO2 and / or Al2O3. The molecular sieve is selected from one or more of ZSM molecular sieves, β molecular sieves, and Y molecular sieves modified with non-metallic elements and / or metallic elements. The non-metallic elements include phosphorus, and the metallic elements are selected from one or more of iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

15. The catalytic cracking process according to any one of claims 1 to 14, characterized in that, The hydrocarbon raw material is selected from one or more of petroleum hydrocarbons, animal and vegetable oils, synthetic oils, and biomass, wherein the petroleum hydrocarbon has a carbon number greater than or equal to 4.

16. A catalytic cracking reactor system for the production of ethylene and propylene, characterized in that, The reactor system includes at least a control unit, a first reaction zone, and a second reaction zone downstream of the first reaction zone. The first reaction zone has an inlet for hydrocarbon feedstock below or at its lower part, and the first reaction zone also has an inlet for catalyst. The control unit is configured to set the average solid content of the catalyst in the first reaction zone to be greater than 0.2, and the volume percentage of the region in the first reaction zone with a catalyst solid content greater than 0.2 is 0.2 to 0.7, and to set the average solid content of the catalyst in the second reaction zone to be less than 0.

1.

17. The catalytic cracking reactor according to claim 16, characterized in that, The first reaction zone and the second reaction zone are coaxially arranged to form a reactor. The first reaction zone accounts for 0.1 to 0.4% of the total height of the reactor, and the second reaction zone accounts for 0.6 to 0.9% of the total height of the reactor. Optionally, the reactor further includes a transition zone disposed between the first reaction zone and the second reaction zone; the first reaction zone accounts for 0.1 to 0.4% of the total height of the reactor, the second reaction zone accounts for 0.5 to 0.8% of the total height of the reactor, and the remaining height is the transition zone.

18. The catalytic cracking reactor of claim 17, wherein, The radial cross-section of the transition zone is circular, and the longitudinal cross-section along the axis is a symmetrical straight line or curve with the axis as the axis of symmetry.

19. Catalytic cracking reactor according to any one of claims 16-18, characterized in that The first reaction zone is a constant diameter reaction zone with a height-to-diameter ratio of 0.5 to 20:1, preferably 1 to 10:1; The second reaction zone is a diameter-reducing reaction zone, with circular cross-sections at both the top and bottom, and the diameter ratio of the top and bottom cross-sections is 0.1 to 0.5:

1.

20. The catalytic cracking reactor according to any one of claims 16-18, characterized in that, The first reaction zone is one or a combination of two of the following: constant diameter fluidized bed and variable diameter fluidized bed; The second reaction zone is one or a combination of two of the following: a constant diameter riser and a variable diameter riser.

21. A catalytic cracking system for the production of ethylene and propylene, characterized in that, It includes the catalytic cracking reactor system of claim 16, the regenerator, and the settling tank. The catalytic cracking reactor system is configured to allow hydrocarbon feedstocks to contact with a catalyst to produce a reactive oil. The settler is configured to allow gas-solid separation of the reactant to yield coked catalyst and oil gas containing ethylene and propylene. The regenerator is configured to regenerate the coked catalyst from the settling tank and return the regenerated catalyst to the catalytic cracking reactor system.

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