A method for preparing light olefins from methanol

Abstract

A method for preparing low-carbon olefins from methanol. The method adopts a two-stage fluidized bed reactor, the upper section is an MTO reaction section, and the lower section is a C4C5 reaction section. The method comprises the following steps: after the raw material methanol is heated by vaporization heat exchange, it enters the fluidized bed reactor from the lower part of the MTO reaction section, and generates low-carbon olefins under the action of a modified ZSM-5 molecular sieve catalyst, and the reaction product flows out from the top of the fluidized bed reactor, enters the subsequent separation system after heat exchange cooling, and separates dry gas, ethylene, propylene, C4, C5 and aromatic oil; ethylene and propylene products exit the device, and the C4 deetherification device reacts to generate MTBE, and C5 and C4 after etherification are mixed and returned to the fluidized bed reactor from the lower part of the C4C5 reaction section. This process method combines the characteristics of the ZSM-5 molecular sieve catalyst, adopts a two-stage fluidized bed reactor and a matching regenerator, so that the reaction of methanol to olefins and the cracking reaction of C4 and C5 are carried out in the same fluidized bed reactor, and a reaction regeneration system and a set of separation systems are shared, which fully utilizes the reaction heat, reduces the energy consumption of the device, and improves the yield of the target products ethylene and propylene.

Description

Technical Field

[0001] The present invention relates to a process for preparing low-carbon olefins such as ethylene and propylene from methanol as a raw material. Specifically, a fluidized bed reactor is divided into two reaction sections, and the methanol-to-olefin reaction and the pyrolysis reaction of carbon four and carbon five after etherification are carried out in the same fluidized bed reactor, sharing a reaction regeneration system and a set of separation systems, which simplifies the equipment, fully utilizes the reaction heat, and improves the yield of ethylene and propylene. Background Art

[0002] Ethylene and propylene are important basic chemical products, which are mainly produced by naphtha cracking. With the development of economy and society, the demand for ethylene and propylene continues to grow rapidly worldwide, while at the same time, non-renewable petroleum resources are becoming increasingly scarce. The technology of synthesizing low-carbon olefins from methanol using coal, natural gas and other raw materials has emerged, providing a non-petroleum route for the preparation of low-carbon olefins, giving full play to my country's coal resource advantages, making up for the shortage of petrochemical raw materials, and conforming to my country's basic national conditions of rich coal and less oil.

[0003] In recent years, methanol to low-carbon olefin technology has received more and more attention. According to the different product distribution, methanol to low-carbon olefin technology is mainly divided into MTO technology and MTP technology. MTO technology generally uses a fluidized bed reactor and SAPO-34 molecular sieve catalyst to produce low-carbon olefins mainly composed of ethylene and propylene in one step. MTP technology generally uses a fixed bed reactor and ZSM-5 molecular sieve catalyst for two-step preparation. First, methanol is converted into a stream containing dimethyl ether in a DME reactor, and then the dimethyl ether stream enters the MTP reactor to produce low-carbon olefins mainly composed of propylene.

[0004] MTP technology requires recycling of a large amount of circulating hydrocarbons and uses process steam to control the reaction temperature, resulting in high energy consumption and low propylene yield. MTO technology is more mature than MTP technology. Currently, the research on MTO technology focuses on developing new catalysts, reducing the coking rate of catalysts, and increasing the yield of ethylene and propylene.

[0005] CN102060644B discloses a method for preparing olefins by a two-step methanol process, wherein the catalytic reaction system comprises a catalytic distillation reactor and a moving bed reactor, and the catalysts are both ZSM-5 molecular sieve catalysts. In order to improve the olefin yield, the C4 hydrocarbon stream and the C5-C7 hydrocarbon stream separated from the reaction product enter two fixed bed reactors for catalytic reaction respectively. The method requires multiple reactors, and no yield data is given.

[0006] CN111423302A discloses "a method and device for producing olefins from methanol", including a methanol-to-olefins reactor, a pre-reactor and a catalyst complete regenerator, wherein the feed of the pre-reactor is C4 and / or C5+ hydrocarbons obtained by separating the products. Different from the incomplete regeneration in the prior art, the spent catalyst from the methanol reactor of this method is completely regenerated, and the regenerated agent is pre-carbonized in the pre-reactor and then returned to the methanol reactor. This method can improve the utilization rate of the catalyst, reduce the unit consumption of methanol, and increase the yield of low-carbon olefins. The method adds a pre-reactor for converting C4 and / or C5+ hydrocarbons. The embodiment uses an SMC-001 catalyst with an active component of SAPO-34. The yield of ethylene + propylene in the product is 84.98%, and the unit consumption of methanol is 2.96 tons.

[0007] CN112299939A discloses "a method and system for producing olefins from methanol", including a methanol-to-olefins reactor, a cracking reactor, a regenerator and a gas-solid separator, wherein the feed of the cracking reactor is C4+ hydrocarbons. The system divides the semi-spent catalyst (carbon-containing catalyst) from the cracking reactor into two streams, which go to the methanol reactor and the regenerator respectively. Compared with the prior art, the extra semi-spent catalyst going to the regenerator increases the circulation of the catalyst, reduces the coking rate, and at the same time, a large amount of regenerated catalyst from the regenerator provides sufficient cracking heat for the cracking of C4+ hydrocarbons, ultimately increasing the total ethylene and propylene yield. The method adds a cracking reactor for converting C4+ hydrocarbons. The catalyst grade of the embodiment is SMC-001, and its active component is SAPO-34. The methanol unit consumption in the embodiment is about 2.65.

[0008] CN101402538B discloses "a method for improving the yield of light olefins". The fluidized bed reaction device of the method is composed of a first reaction zone, a second reaction zone, and a gas-solid separation zone from bottom to top, wherein the raw material of the first reaction zone is methanol, and the axial feed of the second reaction zone includes unreacted methanol, dimethyl ether or hydrocarbons with carbon content of four or more. The raw material methanol reacts in the first reaction zone to generate light olefins, and then enters the second reaction zone with the catalyst to continue to generate a logistics with a higher content of light olefins, and finally enters the gas-solid separation zone, and a part of the separated spent catalyst is regenerated, and a part is returned to the first reaction zone. The catalyst used in the method is a SAPO-34 molecular sieve catalyst, and the yield of light olefins in the embodiment reaches 87.44%.

[0009] In summary, the current method for improving the yield of low-carbon olefins in methanol-to-olefins technology is mainly to catalytically crack or steam crack the by-products C4 and above hydrocarbons generated by the reaction to produce ethylene and propylene. Because the carbon-deposited SAPO molecular sieve catalyst is more conducive to the methanol-to-olefins reaction, the highly active SAPO molecular sieve regeneration agent is more conducive to the hydrocarbon cracking reaction. Therefore, the highly active regeneration agent from the regenerator is usually pre-carbonized in the C4+ hydrocarbon cracking reactor before entering the methanol reactor. Summary of the invention

[0010] The purpose of the present invention is to provide a process for preparing low-carbon olefins such as ethylene and propylene using methanol as a raw material. The method simplifies the equipment, makes full use of the reaction heat effect, greatly reduces the energy consumption of the device, and can obtain high-yield ethylene and propylene products with adjustable P / E ratio (propylene / ethylene), and by-produce MTBE (methyl tertiary butyl ether) and aromatics, greatly improving the economic benefits of the refinery.

[0011] To achieve the above object, the present invention comprises the following steps:

[0012] (1) After being heated by vaporization heat exchange, the raw material methanol enters the fluidized bed reactor from the lower part of the MTO reaction section, and generates the target products ethylene and propylene under the action of the modified ZSM-5 molecular sieve catalyst; the reactor is a two-stage fluidized bed reactor, the upper section is the MTO reaction section, and the lower section is the C4C5 reaction section;

[0013] (2) After the entrained catalyst is recovered by a cyclone separator, the reaction product flows out from the top of the fluidized bed reactor, is heat-exchanged and cooled with recycled C5 and C4 after etherification, and raw methanol, and then enters a quenching tower and a subsequent separation system to separate dry gas, ethylene, propylene, C4, C5, and aromatic oil;

[0014] (3) Dry gas is recycled or vented, ethylene and propylene products are discharged from the device, and the C4 deetherification device reacts to generate MTBE products. The mixed hydrocarbons of C5 and C4 after etherification are heated and returned to the fluidized bed reactor from the lower part of the C4C5 reaction section, where they come into contact with the carbon-deposited ZSM-5 molecular sieve catalyst and are cracked to generate the target products of ethylene and propylene. The generated spent catalyst is divided into two streams after passing through the stripping section. One stream enters the regenerator through the spent catalyst U-tube for char regeneration, and the other stream is mixed with the high-temperature regenerated catalyst from the regenerator. The mixed catalyst is returned to the fluidized bed reactor from the upper part of the MTO reaction section.

[0015] The reactor described in the present invention is a two-stage fluidized bed reactor, the upper section is the MTO reaction section, and the lower section is the C4C5 reaction section. The gas-solid separation section is connected above the MTO reaction section, and the entrained catalyst is recovered by a cyclone separator. The stripping section is connected below the C4C5 reaction section to recover the reaction gas entrained by the spent catalyst.

[0016] In step (1), the raw material methanol enters the fluidized bed reactor from the lower part of the MTO reaction section, contacts with the mixed agent, and reacts to generate light olefins.

[0017] In step (3), the mixed hydrocarbons of C5 and C4 after etherification enter the fluidized bed reactor from the lower part of the C4C5 reaction section, contact with the carbon-deposited ZSM-5 molecular sieve catalyst, and are cracked to generate the target products ethylene and propylene.

[0018] In the present invention, the raw material methanol entering the reactor can also be a mixture of methanol and / or dimethyl ether. A proper amount of water vapor can be added to the raw material to reduce the coking and deactivation of the catalyst.

[0019] The mixed hydrocarbon material entering the reactor can be C4 and / or C4+ hydrocarbons produced by the device itself, or C4 and / or C4+ hydrocarbons from other sources.

[0020] In the present invention, the catalyst circulates between the two-stage fluidized bed reactor and the matching regenerator.

[0021] The regenerated agent passes through the stripping section of the regenerator, the regenerated agent U-shaped tube, and is mixed with part of the regenerated agent from the bottom of the stripping section of the fluidized bed reactor, and then enters the fluidized bed reactor from the upper part of the MTO reaction section. Under the action of the mixed agent, the MTO reaction section mainly undergoes the reaction of methanol to light olefins and forms a carbon deposit catalyst.

[0022] Under the action of the carbon deposition catalyst, the C4C5 reaction section mainly undergoes the reaction of C5 and ether followed by C4 cracking to generate ethylene and propylene. The spent catalyst formed is divided into two streams after passing through the stripping section. One stream enters the regenerator through the spent catalyst U-shaped tube for char regeneration, and the other stream is mixed with the regenerated catalyst from the regenerator after heat exchange cooling. The mixed catalyst returns to the fluidized bed reactor from the upper part of the MTO reaction section.

[0023] In the present invention, the reaction of methanol to produce low-carbon olefins and the reaction of C5 and C4 cracking to produce ethylene and propylene are carried out in the same fluidized bed reactor. The MTO reaction section provides the C4C5 reaction section with a ZSM-5 molecular sieve catalyst with low activity, especially low hydrogen transfer activity, which is more conducive to the carbon deposition of cracking reaction to produce propylene. At the same time, the catalyst, as a heat carrier, also takes away the heat of the MTO reaction section, weakens the exothermic effect of the MTO reaction section, and provides heat to the strongly endothermic C4C5 reaction section.

[0024] The part of spent catalyst from the C4C5 reaction section that has been stripped and cooled is mixed with the high-temperature and high-activity regenerated catalyst from the regenerator and returned to the MTO reaction section. The temperature and circulation volume of the part of spent catalyst are adjusted so that the average carbon content and operating temperature of the mixed catalyst entering the MTO reaction section reach the appropriate range for the methanol to olefins reaction.

[0025] In the fluidized bed reactor of the present invention, the temperature of the MTO reaction section is 450-550°C, the temperature of the C4C5 reaction section is 460-580°C, and the reaction pressure is 0.01-0.5MPa. The regeneration temperature of the matching regenerator is 580-650°C, the operating pressure is 0.1-0.5MPa, and the average residence time of the catalyst is 10-30min.

[0026] The catalyst is a modified ZSM-5 molecular sieve catalyst, and its modifying element is at least one of group IA, group VA, group II B, group VIB, and rare earth elements. Based on the total weight of the catalyst, the catalyst contains 40-90% of molecular sieve, 10-50% of clay, 5-20% of binder, and 0.1-10% of modifying element. The clay is well known to those skilled in the art, and can be one or a mixture of kaolin, diatomaceous earth, montmorillonite, bentonite, and attapulgite; the binder is one or a mixture of pseudo-boehmite, aluminum sol, silica aluminum sol, and water glass; the modifying element in the catalyst can be one or more of the metal oxide, phosphate, phosphite, basic phosphate or acid phosphate.

[0027] The catalyst of the present invention can be prepared by a general method: first, the molecular sieve and clay are slurried and mixed with water to form a slurry; then, a modifying element precursor is added to the molecular sieve slurry, and the mixture is slurried and mixed evenly; a binder is added to the clay slurry, and after the mixture is slurried and mixed evenly, the molecular sieve slurry is added, and the mixture is slurried and mixed evenly to form a catalyst slurry; the catalyst slurry is spray-dried to form; and the formed microspheres are calcined or washed and dried to obtain the molecular sieve catalyst.

[0028] In the present invention, the reaction product flows out from the top of the fluidized bed reactor, and is successively heat exchanged with the recycled C5 and C4 after etherification and the raw material methanol, and then enters the quenching tower after cooling. The two-stage heat exchange fully utilizes the heat brought out by the reaction product, preheats the two feeds of the fluidized bed reactor, and at the same time, the product temperature is cooled to the appropriate range of the feed of the quenching tower.

[0029] The gas at the top of the quench tower is compressed and enters the subsequent separation system to separate dry gas, ethylene, propylene, C4, C5 and aromatic oil. The dry gas is recycled or vented; ethylene and propylene products are discharged from the device; the C4 deetherification device reacts the by-product isobutylene to produce MTBE products; the mixed hydrocarbons of C5 and C4 after etherification are heated and returned to the fluidized bed reactor from the lower part of the C4C5 reaction section to continue the reaction to produce the target products ethylene and propylene; the by-product aromatic oil can be used as a high-octane gasoline component.

[0030] The present invention has the following effects:

[0031] (1) The reaction of methanol to produce low-carbon olefins and the cracking of ether into C4 and C5 to produce ethylene and propylene are carried out in the same fluidized bed reactor and share a reaction regeneration system and a separation system. This not only simplifies the equipment but also makes full use of the reaction heat, greatly reduces the energy consumption of the device, and improves the selectivity and yield of the target products ethylene and propylene.

[0032] (2) The catalyst of the present invention circulates between the fluidized bed reactor and the matching regenerator, the average carbon content and the operating temperature are controllable and adjustable, and the energy utilization is reasonable and efficient.

[0033] (3) The reaction regeneration system of the present invention has a simple structure, is easy to operate and has high safety.

[0034] (4) Compared with the existing methanol to olefins technology, the present invention adopts a modified ZSM-5 molecular sieve catalyst, which produces less coke and dry gas, and produces more propylene and ethylene. The by-product isobutylene, which is converted into MTBE product through an etherification device. Aromatic oil is used as a high-octane gasoline component, and the carbon four and carbon five after etherification are returned to the fluidized bed reactor for further cracking reaction to generate the target product. The selectivity and yield of ethylene and propylene are higher.

[0035] (5) The present invention can obtain high-yield ethylene and propylene products with adjustable P / E ratio, and produce MTBE and aromatics as by-products. The whole set of equipment is simple, easy to operate, and has lower energy consumption, which is suitable for the industrial production of low-carbon olefins. When the present invention is applied industrially, the methanol conversion rate can reach 99.9%, and the ethylene and propylene yields can reach 88%. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the process flow of the method of the present invention, but the present invention is not limited to this.

[0037] 1-raw material heat exchanger, 2-methanol drum, 3-methanol vaporizer, 4-methanol heating furnace, 5-fluidized bed reactor, 6-regenerator, 7-reaction product heat exchanger, 8-refining heating furnace, 9-quenching tower, 10-liquid separation tank, 11-compressor, 12-separation system, 13-etherification device, 14-sedimentation tank, 15-methanol recovery tower.

[0038] like Figure 1 The process flow of this method shown is:

[0039] After the raw material methanol is heated by vaporization heat exchange, it enters the fluidized bed reactor from the lower part of the MTO reaction section, and reacts with the mixed agent to generate reaction products containing light olefins. After the reaction product is recovered by the cyclone separator and the entrained catalyst, it flows out from the top of the fluidized bed reactor, and is successively cooled by heat exchange with the recycled C5 and C4 after etherification, and the raw material methanol, and enters the quenching tower and subsequent separation system to separate dry gas, ethylene, propylene, C4, C5 and aromatic oil.

[0040] The dry gas is recycled or vented, ethylene and propylene products are discharged from the device, and the C4 deetherification device reacts to generate MTBE products. The mixed hydrocarbons of C5 and C4 after etherification are heated and returned to the fluidized bed reactor from the lower part of the C4C5 reaction section, where they contact the carbon deposition catalyst and are cracked to generate the target products of ethylene and propylene, and to form spent catalyst. The cracked gas enters the MTO reaction section upward; the spent catalyst formed is divided into two streams after passing through the stripping section, one stream enters the regenerator through the spent catalyst U-shaped tube for char regeneration, and the other stream is mixed with the regenerated catalyst from the regenerator and returned to the fluidized bed reactor from the upper part of the MTO reaction section.

[0041] Figure 2 It is a schematic structural diagram of the fluidized bed reactor and the matching regenerator of the present invention.

[0042] 1-reaction product outlet, 2-reactor cyclone separator, 3-gas-solid separation section, 4-regeneration agent cyclone distributor, 5-MTO reaction section, 6-feed distributor, 7-methanol / dimethyl ether feed port, 8-C4C5 reaction section, 9-cracking reactant feed port, 10-internal heat extraction pipe, 11-stripping steam inlet, 12-riser stripping steam, 13-riser pipe for regenerated agent, 14-U-shaped pipe for regenerated agent, 15-lifting steam inlet, 16-slide valve for regenerated agent, 17-lifting Nitrogen inlet, 18-regeneration agent slide valve, 19-regeneration agent external circulation slide valve, 20-regeneration agent U-shaped tube, 21-regeneration agent riser, 22-gas stripping nitrogen inlet, 23-regeneration agent stripping section, 24-gas stripping nitrogen inlet, 25-regenerator internal heat extractor, 26-high temperature burner inlet, 27-regeneration air inlet, 28-regeneration dense phase bed, 29-regeneration agent cyclone distributor, 30-regenerator cyclone separator, 31-CO boiler, 32-regeneration flue gas outlet.

[0043] like Figure 2 As shown, the upper section of the two-stage fluidized bed reactor is the MTO reaction section, and the lower section is the C4C5 reaction section. The gas-solid separation section is connected above the MTO reaction section, and the entrained catalyst is recovered by a cyclone separator. The stripping section is connected below the C4C5 reaction section to recover the reaction gas entrained by the spent catalyst.

[0044] A U-shaped tube is used to transfer the catalyst between the fluidized bed reactor and the matching regenerator.

[0045] The regenerated agent passes through the regenerator stripping section, the regenerated agent U-shaped tube, and is mixed with part of the unregenerated agent from the bottom of the stripping section of the fluidized bed reactor, and then enters the fluidized bed reactor from the upper part of the MTO reaction section.

[0046] The spent agent is divided into two streams after passing through the stripping section of the reactor. One stream enters the regenerator through the spent agent U-tube for char regeneration, and the other stream is mixed with the regenerated agent from the regenerator after heat exchange cooling. The mixed agent returns to the fluidized bed reactor from the upper part of the MTO reaction section. DETAILED DESCRIPTION

[0047] The present invention is further described below with reference to embodiments, but the present invention is not limited thereto.

[0048] Raw material specifications

[0049] (1) The experimental raw materials are mixed feeds consisting of industrial methanol, C4 and C5, with a mixing ratio of 70:25:5. The C4 is taken from the etherified C4 of the catalytic cracking unit of Ningxia Petrochemical Company, and its composition is shown in Table 1; the C5 is taken from the raw material C5 of the etherification of light gasoline of Ningxia Petrochemical Company.

[0050] (2) Catalyst model XMTO-1, with a φ10μm spherical appearance. This catalyst model is produced by Beijing Huier Sanji Green Chemical Technology Co., Ltd., and contains 56.8% ZSM-5, 1.5% P2O5, 2.8% K2O, 2.8% CdO, 0.46% ZnO and the balance Al2O3. The ZSM-5 molecular sieve is synthesized by in-situ crystallization method, and the silicon-aluminum ratio is 200.

[0051] Example 1

[0052] This example illustrates the effect of implementing a method for producing low-carbon olefins from methanol through experimental data.

[0053] The test device is a riser reactor with a catalyst storage capacity of 10 kg. The test raw materials methanol, water, ether, C4 and C5 are respectively pumped into the preheating furnace by metering pumps, and then enter the riser reactor from the bottom of the reactor. The oil and gas mixture generated by the reaction is heat exchanged and the pressure is controlled by a regulating valve. After condensation and a gas-liquid separator, the liquid generated by the reaction is separated and weighed, the gas is measured by a wet flow meter, and the liquid and gas are sampled and analyzed for composition by gas chromatography, and the yield (based on the weight of the raw material methanol) is calculated.

[0054] The flow rate of raw material methanol is 3kg / h, and the flow rate of water is 2kg / h. The preheating temperature is 350℃, the reaction temperature is 520℃, and the reaction pressure is 0.1MPa (gauge pressure). The reaction is continued for 7 days, and the material balance is checked every day. The reaction gas is taken twice for composition analysis, and the liquid is collected once for composition analysis. After the 7-day reaction, the coke yield is calculated. Table 2 is the average data for 7 days.

[0055] Table 1 Ether post-C4 composition

[0056] name Volume composition, v% C3 0.45 n-Butane 12.62 Isobutane 39.23 n-Butene 16.62 Isobutylene 0.84 Trans-Butene 17.06 Cis-Butene 12.8 C5 0.38 total 100

[0057] Table 2 Reaction conditions and product distribution of the embodiment

[0058] Test No. Example 1 catalyst XMTO-1 Reaction temperature, °C 520 Reaction pressure, MPa 0.1 <![CDATA[Methanol feed space velocity, h -1 > 0.3 Water vapor ratio, wt% 66.7 Reaction product distribution, wt% hydrogen 0.03％ Methane 0.42％ Ethane 0.17％ Ethylene 3.86％ Propane 0.34％ Propylene 14.44％ Isobutane 2.99％ n-Butane 0.30％ Trans-Butene 2.13％ n-Butene 1.43％ Isobutylene 3.13％ Cis-Butene 2.07％ C5+ gasoline 7.69％ Carbon monoxide 0.02％ carbon dioxide 0.01％ Methanol 0.01％ water 60.12％ Coke 0.85％ total 100

Claims

1. A method for preparing light olefins from methanol, comprising the following steps: (1) After being heated by vaporization heat exchange, the raw material methanol enters the fluidized bed reactor from the lower part of the MTO reaction section, and generates the target products ethylene and propylene under the action of the modified ZSM-5 molecular sieve catalyst; the reactor is a two-stage fluidized bed reactor, the upper section is the MTO reaction section, and the lower section is the C4C5 reaction section; the modified element of the catalyst is at least one from Group IA, Group VA, Group IIB, Group VIB, and rare earth elements; (2) After the entrained catalyst is recovered by a cyclone separator, the reaction product flows out from the top of the fluidized bed reactor, is heat-exchanged and cooled with recycled C5 and C4 after etherification, and raw methanol, and then enters a quenching tower and a subsequent separation system to separate dry gas, ethylene, propylene, C4, C5, and aromatic oil; (3) Dry gas is recycled or vented, ethylene and propylene products are discharged from the device, and the C4 deetherification device reacts to generate MTBE products. The mixed hydrocarbons of C5 and C4 after etherification are heated and returned to the fluidized bed reactor from the lower part of the C4C5 reaction section, where they come into contact with the carbon-deposited ZSM-5 molecular sieve catalyst and are cracked to generate the target products ethylene and propylene. The generated spent catalyst is divided into two streams after passing through the stripping section. One stream enters the regenerator through the spent catalyst U-tube for char regeneration, and the other stream is mixed with the high-temperature regenerated catalyst from the regenerator and returned to the fluidized bed reactor from the upper part of the MTO reaction section.

2. The method according to claim 1, characterized in that In step (1), the raw material methanol enters the fluidized bed reactor from the lower part of the MTO reaction section to generate the target products ethylene and propylene; in step (3), the mixed hydrocarbons of C5 and C4 after etherification enter the fluidized bed reactor from the lower part of the C4C5 reaction section to be cracked to generate the target products ethylene and propylene.

3. The method according to claim 1, characterized in that In step (3), the regenerated agent passes through the regenerator stripping section, through the regenerated agent U-shaped tube, and is mixed with a portion of the unregenerated agent from the bottom of the stripping section of the fluidized bed reactor. The mixed agent then enters the fluidized bed reactor from the upper part of the MTO reaction section. Under the action of the mixed agent, the MTO reaction section mainly undergoes a reaction of methanol to generate light olefins, and forms a carbon deposition catalyst.

4. The method according to claim 1, characterized in that In step (3), under the action of the carbon deposition catalyst, the C4C5 reaction section mainly undergoes the cracking reaction of C5 and ether followed by C4 to generate ethylene and propylene; the generated spent agent is divided into two streams after passing through the stripping section, one stream enters the regenerator through the spent agent U-tube for char regeneration, and the other stream is mixed with the regenerated agent from the regenerator after heat exchange cooling, and the mixed agent returns to the fluidized bed reactor from the upper part of the MTO reaction section.

5. The method according to claim 1, characterized in that The reaction of methanol to produce low-carbon olefins and the reaction of C5 and C4 cracking to produce ethylene and propylene are carried out in the same fluidized bed reactor and share a reaction regeneration system and a separation system.

6. The method according to claim 5, characterized in that The MTO reaction section provides the C4C5 reaction section with a carbon-deposited ZSM-5 molecular sieve catalyst that is more suitable for cracking reactions. At the same time, the catalyst, as a heat carrier, takes away the heat of the MTO reaction section, weakening the exothermic effect of the MTO reaction section and providing heat to the strongly endothermic C4C5 reaction section.

7. The method according to claim 5, characterized in that Part of the spent catalyst from the C4C5 reaction section that is stripped and cooled and returns to the MTO reaction section is mixed with the high-temperature regenerated catalyst from the regenerator, so that the average carbon content and temperature of the catalyst entering the MTO reaction section reach the appropriate range for the methanol to olefins reaction.

8. The method according to claim 1, characterized in that The reaction pressure of the fluidized bed reactor is 0.01-0.5 MPa, the temperature of the MTO reaction section is 450-550°C, and the temperature of the C4C5 reaction section is 460-580°C.

9. The method according to claim 1, characterized in that In step (1), the raw material methanol entering the reactor may also be a mixture of methanol and / or dimethyl ether; an appropriate amount of water vapor may be added to the raw material to reduce the deactivation of the catalyst due to coking.

10. The method according to claim 1, characterized in that In step (3), the mixed hydrocarbon material entering the reactor can be C4 and / or C4+ hydrocarbons produced by the device itself, or C4 and / or C4+ hydrocarbons from other sources.

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