Fluidized bed system and method for producing low carbon olefins by carbon dioxide hydrogenation

Abstract

The application belongs to the technical field of petroleum chemical industry, and particularly relates to a fluidized bed system for producing low-carbon olefins by carbon dioxide hydrogenation and a preparation method. The system comprises a fluidized bed reactor dilute phase settling section, the bottom of the fluidized bed reactor dilute phase settling section is connected with a fluidized bed reactor dense phase reaction section, the outside of the fluidized bed reactor is provided with a catalyst circulation temperature controller, the catalyst circulation temperature controller is connected with the bottom of the fluidized bed reactor dilute phase settling section and the fluidized bed reactor dense phase reaction section through a circulating heat-removing catalyst conveying pipe respectively, and a heat-removing catalyst amount control valve is arranged on the circulating heat-removing catalyst conveying pipe between the fluidized bed reactor dense phase reaction section and the catalyst circulation temperature controller. The application effectively controls the reaction temperature, saves the catalyst regeneration process, and reduces the energy consumption of the system. According to the actual situation, the catalyst circulation temperature controller and the fluidized bed regenerator are used flexibly to make the catalyst reaction cycle efficient and low in energy consumption.

Description

Technical Field

[0001] This patent belongs to the field of petrochemicals, specifically relating to a fluidized bed system and preparation method for producing low-carbon olefins by hydrogenation of carbon dioxide. Background Technology

[0002] Low-carbon olefins mainly refer to ethylene and propylene, which are very important organic chemical raw materials used to produce chemical products such as polyethylene, polypropylene, and ethylene oxide. Traditionally, ethylene and propylene are mainly produced through the petroleum route. Traditional production methods are energy-intensive, polluting, and have high carbon emissions. Furthermore, my country's petroleum resources are relatively scarce. Therefore, using renewable energy sources and non-fossil energy sources as carbon sources to produce low-carbon olefins can not only reduce carbon emissions but also fully utilize renewable energy to produce chemicals, thus reducing dependence on fossil fuels. This is of great significance for the production of ethylene, propylene, and other low-carbon olefins.

[0003] Chinese patent CN202962437U discloses a fluidized bed reaction regeneration device, belonging to the technical field of petrochemical and coal chemical equipment, used to produce low-carbon olefins, gasoline, and aromatics from methanol. The device includes a reactor, a regenerator, a catalyst stripping conveying pipe, and an external heat exchanger for the regenerator. This invention employs an air-lifted catalyst conveying pipe, with the upper part of the catalyst stripping section connected to the reactor and simultaneously connected to the lower part of the regenerated catalyst stripping section via a hot regenerated catalyst pipe. The catalyst transport does not require nitrogen or steam, reducing energy consumption; incorporating a high-temperature regeneration catalyst into the catalyst increases the temperature and improves stripping efficiency. It is applicable to the comprehensive utilization of methanol.

[0004] Fossil fuels (coal, oil, and natural gas) have provided enormous economic benefits to human society, but they have also caused environmental problems such as global warming. Therefore, a production system and preparation method are needed that can utilize cleaner raw materials to address the greenhouse effect, replace fossil fuels, and produce chemicals with higher economic value, while also possessing advantages such as low energy consumption. This would be of great significance to the sustainable development of global energy and the ecological environment. Summary of the Invention

[0005] This invention provides a fluidized bed system and preparation method for the production of low-carbon olefins by carbon dioxide hydrogenation. This invention enables effective control of the reaction temperature, saves the catalyst regeneration process, and reduces the energy consumption of the system. This invention flexibly uses a catalyst circulation temperature controller and a fluidized bed regenerator according to actual conditions to make the catalytic reaction cycle highly efficient and energy-saving.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A fluidized bed system for producing low-carbon olefins by hydrogenation of carbon dioxide includes a dilute phase settling section of a fluidized bed reactor. The bottom of the dilute phase settling section is connected to a dense phase reaction section of the fluidized bed reactor. A catalyst circulation temperature controller is provided outside the dense phase reaction section. The catalyst circulation temperature controller is connected to the bottom of the dilute phase settling section and the dense phase reaction section of the fluidized bed reactor respectively through a circulating heat-extracting catalyst delivery pipe. A heat-extracting catalyst quantity control valve is provided on the circulating heat-extracting catalyst delivery pipe between the dense phase reaction section and the catalyst circulation temperature controller.

[0008] Preferably, the bottom of the dilute phase settling section of the fluidized bed reactor is connected to the dense phase section of the fluidized bed regenerator via a catalyst delivery pipe, and the catalyst delivery pipe is equipped with a catalyst quantity control valve.

[0009] More preferably, the top of the dense phase section of the fluidized bed regenerator is connected to the dilute phase settling section of the fluidized bed regenerator.

[0010] More preferably, the circulating heat-extracting catalyst delivery pipe between the catalyst circulation temperature controller and the heat-extracting catalyst quantity control valve is connected to a regenerated catalyst delivery pipe, and the other end of the regenerated catalyst delivery pipe is connected to the bottom of the dilute phase settling section of the fluidized bed regenerator; a regenerated catalyst temperature controller is provided on the regenerated catalyst delivery pipe.

[0011] More preferably, the bottom of the dense phase section of the fluidized bed regenerator is provided with a regeneration air inlet, and a regeneration air distributor is provided above the regeneration air inlet.

[0012] More preferably, the top of the dilute phase settling section of the fluidized bed regenerator is provided with a regenerated flue gas outlet, and a gas-solid separator for the dilute phase settling section of the regenerator is provided below the regenerated flue gas outlet.

[0013] Preferably, the bottom of the dense phase reaction section of the fluidized bed reactor is provided with a carbon dioxide hydrogenation feed inlet, and a carbon dioxide hydrogenation feed distributor is provided above the carbon dioxide hydrogenation feed inlet.

[0014] Preferably, the top of the dilute phase settling section of the fluidized bed reactor is provided with a carbon dioxide hydrogenation product outlet, and a gas-solid separator for the dilute phase settling section of the reactor is provided below the carbon dioxide hydrogenation product outlet.

[0015] Preferably, an even number of catalyst circulation temperature controllers are provided on the outside of the fluidized bed reactor, and the catalyst circulation temperature controllers are evenly distributed on the outside of the fluidized bed reactor.

[0016] The present invention also claims a method for producing low-carbon olefins by hydrogenating carbon dioxide using the above system, comprising the following steps: mixing raw carbon dioxide and raw hydrogen in a volume ratio of 1:(2-9) and pressurizing to 3-5 MPa, preheating to 250-400°C, then entering the dense phase reaction section of a fluidized bed reactor and adding a catalyst, and reacting at a temperature of 250-400°C for 5-15 seconds to produce low-carbon olefins.

[0017] Preferably, the catalyst comprises 10-80 wt% nano-metal oxide and 20-90 wt% modified ZSM-5 molecular sieve. The nano-metal oxide and modified ZSM-5 molecular sieve are treated with a silane coupling agent, a binder is added to form a slurry, and finally the slurry is shaped by spray drying and then calcined to obtain the carbon dioxide hydrogenation catalyst.

[0018] More preferably, the carbon dioxide hydrogenation catalyst comprises 20-50 wt% nano-metal oxide and 50-80 wt% modified ZSM-5 molecular sieve. The nano-metal oxide and modified ZSM-5 molecular sieve are treated with a silane coupling agent and then calcined to obtain the carbon dioxide hydrogenation catalyst.

[0019] More preferably, the nano-metal oxide includes component A and component B, wherein component A is selected from any three of iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and component B is selected from any one of zirconium oxide, potassium oxide, and calcium oxide.

[0020] More preferably, component A includes component 1, component 2, and component 3, wherein component 1, component 2, and component 3 are any three selected from iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and each accounts for 1 to 80% of the weight percentage of the nano-metal oxide.

[0021] More preferably, component A includes component 1, component 2, and component 3, wherein component 1, component 2, and component 3 are any three selected from iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and each accounts for 10 to 70% of the weight percentage of the nano-metal oxide.

[0022] More preferably, component B accounts for 1 to 10% of the weight of the nano-metal oxide.

[0023] More preferably, component B accounts for 1 to 5% of the weight of the nano-metal oxide.

[0024] More preferably, the modified ZSM-5 molecular sieve includes component a, component b and ZSM-5 molecular sieve, wherein component a is selected from either lanthanum oxide or cerium oxide, and component b is selected from either potassium oxide or magnesium oxide.

[0025] More preferably, component a accounts for 0.1-5% of the weight of the modified ZSM-5 molecular sieve, and component b accounts for 0.1-3% of the weight of the modified ZSM-5 molecular sieve.

[0026] More preferably, component a accounts for 0.5 to 3% of the weight of the modified ZSM-5 molecular sieve, and component b accounts for 0.1 to 1.5% of the weight of the modified ZSM-5 molecular sieve.

[0027] More preferably, the silane coupling agent is KH560 and / or KH570.

[0028] More preferably, the binder is aluminum sol and / or silica sol.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The catalyst circulation temperature controller of the present invention can be directly applied to the outside of the fluidized bed reactor. Through the cooperation of the fluidized bed reactor and the catalyst circulation temperature controller, the catalyst can be directly circulated externally and the temperature of the catalyst can be controlled within the optimal range, so that the reaction temperature can be effectively controlled, stable and efficient. At the same time, the catalyst regeneration process is saved and the energy consumption of the system is greatly reduced.

[0031] (2) The present invention can intermittently regenerate the catalyst with high carbon content by using a fluidized bed regenerator in conjunction with the catalyst circulation temperature controller, so that the catalyst can be used for a long time, saving materials and production costs, improving carbon dioxide conversion rate, and thus improving economic benefits. At the same time, setting an even number of catalyst circulation temperature controllers can more effectively and flexibly control the temperature. The catalyst circulation temperature controller and fluidized bed regenerator can be used flexibly according to the actual situation, so that the catalyst can be circulated efficiently and with low energy consumption.

[0032] (3) The catalyst of this invention can directly hydrogenate carbon dioxide to produce chemicals such as ethylene, propylene, and butene. The modified ZSM-5 molecular sieve in the catalyst has good hydrothermal stability and coke capacity, which makes the catalyst have good selectivity and lifespan. At the same time, the present invention modifies the nano metal oxide and the modified ZSM-5 molecular sieve with a silane coupling agent. Compared with simple mechanical mixing or binder mixing, it has a tighter connection, higher catalytic efficiency, and can effectively reduce the generation of by-products and improve the conversion rate and target product selectivity. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a fluidized bed system for producing low-carbon olefins by hydrogenation of carbon dioxide according to the present invention.

[0034] The attached figures are labeled as follows: 201, Carbon dioxide hydrogenation feed inlet; 202, Carbon dioxide hydrogenation feed distributor; 203, Dense phase reaction section of fluidized bed reactor; 204, Dilute phase settling section of fluidized bed reactor; 205, Gas-solid separator in the dilute phase settling section of reactor; 206, Carbon dioxide hydrogenation product outlet; 207, Catalyst delivery pipe; 208, Circulating heat-extracting catalyst delivery pipe; 210, Waiting catalyst quantity control valve; 211, Regenerated catalyst temperature controller; 212, Catalyst circulation temperature controller; 214, Heat-extracting catalyst quantity control valve; 215, Regenerated air inlet; 216, Regenerated air distributor; 217, Dense phase section of fluidized bed regenerator; 218, Fluidized bed regenerated dilute phase settling section; 219, Gas-solid separator in the dilute phase settling section of regenerator; 220, Regenerated flue gas outlet; 221, Regenerated catalyst delivery pipe. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Although the steps in this invention are arranged by reference numerals, this is not intended to limit the order of the steps. Unless the order of the steps is explicitly stated or the execution of a step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" as used herein refers to and covers any and all possible combinations of one or more of the associated listed items.

[0037] The specific operating principle of the fluidized bed system for producing low-carbon olefins by carbon dioxide hydrogenation according to the present invention is as follows:

[0038] Carbon dioxide is replenished through a carbon dioxide replenishment device and by chemical absorption, physical absorption, or adsorption. The replenished carbon dioxide is stored in a carbon dioxide storage tank. Hydrogen produced by the alkaline water electrolysis hydrogen production device is stored in a hydrogen storage tank. Then, the raw carbon dioxide and raw hydrogen are mixed in a raw material mixing tank at a volume ratio of 1:(2-9), such as 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, or 1:9. After mixing, the mixture is pressurized to 3-5 MPa, such as 3 MPa. The feed pressure is 3.5 MPa, 4 MPa, 4.5 MPa, and 5 MPa. Then, the feed is preheated in a preheating furnace at a temperature of 250-400℃, for example, 250℃, 300℃, 350℃, or 400℃. After preheating, the feed enters the dense phase reaction section of a fluidized bed reactor and a catalyst is added. After adding the catalyst, the reaction proceeds at a temperature of 250-400℃ to prepare low-carbon olefins, with a reaction time of 5-15 seconds. The reaction temperature can be, for example, 250℃, 300℃, 350℃, or 400℃, and the reaction time can be 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, 11 seconds, 12 seconds, 13 seconds, 14 seconds, or 15 seconds.

[0039] In this process, carbon dioxide and hydrogen feedstocks are preheated and then enter through carbon dioxide hydrogenation feedstock inlet 201. After passing through carbon dioxide hydrogenation feed distributor 202, they undergo a reaction to synthesize low-carbon olefins in the dense phase reaction section 203 of the fluidized bed reactor. The product after the reaction enters the dilute phase settling section 204 of the fluidized bed reactor and is discharged from the carbon dioxide hydrogenation product outlet 206 through the reactor gas-solid separator 205.

[0040] The catalyst leaving the dense phase reaction section 203 of the fluidized bed reactor settles into the circulating heat-extracting catalyst delivery pipe 208, and then returns to the dense phase reaction section 203 of the fluidized bed reactor for a second catalytic reaction after precise temperature control by the catalyst circulation temperature controller 212. The specific amount of catalyst returning to the dense phase reaction section 203 of the fluidized bed reactor is controlled by the heat-extracting catalyst quantity control valve 214.

[0041] The use of a fluidized bed regenerator is determined by measuring the carbon content of the catalyst. This can be done manually or using an online carbon analyzer. The online carbon analyzer performs real-time carbon analysis of the selected catalyst without affecting the normal operation of the fluidized bed unit. The carbon analyzer determines the catalyst carbon content by analyzing the online coking of a small amount of catalyst passing through per unit time and the composition of the resulting flue gas.

[0042] When the carbon content of the catalyst increases to a certain value, the fluidized bed regenerator is turned on, and the catalyst settles into the catalyst delivery pipe 207. Part of the catalyst enters the catalyst circulation temperature controller 212 through the circulating heat extraction catalyst delivery pipe 208, and the other part enters the dense phase reaction section 217 of the fluidized bed regenerator for regeneration through the waiting catalyst quantity control valve 210.

[0043] Regenerated air enters the regenerated air distributor 216 through the regenerated air inlet 215, and then comes into contact with the microsphere catalyst. Under certain conditions, it is regenerated in the dense phase section 217 of the fluidized bed regenerator, and then enters the fluidized bed regenerated dilute phase settling section 218. The regenerated flue gas passes through the gas-solid separator 219 of the dilute phase settling section of the regenerator and the regenerated flue gas outlet 220 in sequence to be discharged.

[0044] The regenerated catalyst enters the regenerated catalyst temperature controller 211 through the regenerated catalyst delivery pipe 221. In the regenerated catalyst temperature controller 211, the catalyst is cooled by heat extraction. The cooled catalyst returns to the dense phase reaction section 203 of the fluidized bed reactor. The amount of cooled catalyst delivered is controlled by the heat extraction catalyst amount control valve 214.

[0045] The catalyst comprises 10-80 wt% nano-metal oxide and 20-90 wt% modified ZSM-5 molecular sieve. The nano-metal oxide and modified ZSM-5 molecular sieve are treated with a silane coupling agent, a binder is added to form a slurry, and finally the slurry is shaped by spray drying and then calcined to obtain the catalyst.

[0046] The nano-metal oxide can account for 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, or 80 wt% of the active component of the catalyst, preferably 20 to 50 wt%.

[0047] The modified ZSM-5 molecular sieve can account for 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, or 90wt% of the active component of the catalyst, preferably 40-80wt%.

[0048] Specifically, the nano-metal oxide includes component A and component B. Component A is selected from any three of iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and component B is selected from any one of zirconium oxide, potassium oxide, and calcium oxide.

[0049] More specifically, component A includes component 1, component 2, and component 3. Component 1, component 2, and component 3 are any three selected from iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and each accounts for 1 to 80% of the weight percentage of the nano-metal oxide. The weight percentages can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%, with a more preferred weight percentage of 10% to 70%.

[0050] More specifically, component B accounts for 1 to 10% of the weight of the nano-metal oxide, and can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, with a more preferred percentage being 1 to 5%.

[0051] Specifically, the modified ZSM-5 molecular sieve includes component a, component b, and ZSM-5 molecular sieve. Component a is selected from either lanthanum oxide or cerium oxide, and component b is selected from either potassium oxide or magnesium oxide.

[0052] More specifically, component a accounts for 0.1% to 5% of the weight of the modified ZSM-5 molecular sieve, and can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, with a more preferred percentage being 0.5% to 3%.

[0053] More specifically, component b accounts for 0.1% to 3% of the weight of the modified ZSM-5 molecular sieve, and can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, with a more preferred percentage being 0.1% to 1.5%.

[0054] Specifically, the silane coupling agent is KH560 and / or KH570.

[0055] Specifically, the binder is aluminum sol and / or silica sol.

[0056] The preparation method of the catalyst includes the following steps:

[0057] (1) Dissolve the first metal salt in deionized water, then add sucrose and polyethylene glycol, stir to obtain a sol, dry and calcine the sol to obtain nano metal oxides;

[0058] Specifically, in step (1), the first metal salt is one or more of the nitrates of Fe, Co, Mo, Ni, Cu, Zr, K, and Ca, and the weight ratio of the first metal salt to deionized water is 15 to 40:100, which can be 15:100, 20:100, 25:100, 30:100, 35:100, or 40:100.

[0059] Specifically, in step (1), the stirring conditions are 40-95℃ for 5-15 hours, the drying conditions are 110-120℃ for 10-15 hours, and the calcination conditions are 400-600℃ for 5-15 hours.

[0060] Specifically, in step (1), the polyethylene glycol is PEG2000 and / or PEG4000;

[0061] Optionally, in step (1), the sucrose is 0.01% to 5% of the weight of the sol, and can be 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, preferably 0.1% to 3%.

[0062] Optionally, in step (1), the polyethylene glycol is 0.01% to 10% of the weight of the sol, and can be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, preferably 0.1% to 5%.

[0063] (2) Dissolve the second metal salt in deionized water to obtain a second metal salt solution, age the ZSM-5 molecular sieve, then impregnate the ZSM-5 molecular sieve with the second metal salt solution, let it stand, dry it, and calcine it to obtain the modified ZSM-5 molecular sieve.

[0064] Specifically, in step (2), the second metal salt is one or more of the nitrates of La, Ce, K, and Mg, and the weight ratio of the second metal salt to deionized water is 10 to 30:100, which can be 10:100, 15:100, 20:100, 25:100, or 30:100.

[0065] Specifically, in step (2), the aging conditions are aging at 550-700℃ for 2-5 hours, the standing time is 10-15 hours, the drying conditions are drying at 100-120℃ for 8-15 hours, and the calcination conditions are calcination at 500-600℃ for 10-15 hours.

[0066] Specifically, in step (2), the ZSM-5 molecular sieve has a particle size of <800nm ​​and a silicon-to-aluminum ratio of 80 to 300, which can be 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300, with a preferred ratio of 100 to 200.

[0067] (3) Disperse nano-metal oxides and modified ZSM-5 molecular sieves in deionized water, add ethanol and silane coupling agent, stir thoroughly to obtain catalyst mixture, add binder to obtain slurry, spray dry the slurry to form a shape, then dry and calcine to obtain carbon dioxide hydrogenation catalyst.

[0068] Specifically, in step (3), ethanol accounts for 0.5% to 3% of the weight of the catalyst mixture, and can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, or 3%.

[0069] Specifically, in step (3), the silane coupling agent accounts for 1 to 5% of the weight of the catalyst mixture, which can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%.

[0070] Specifically, in step (3), the binder accounts for 10-60% of the weight of the slurry; the solid content of the binder is 20-40%.

[0071] More specifically, in step (3), the solid content of the slurry is 25-35 wt%, which can be 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, or 35 wt%.

[0072] Specifically, in step (3), the furnace temperature during spray drying is 300-450℃, the outlet temperature of the drying tower is 130-250℃, and the spray pressure of the drying tower is 2.0-4.0MPa; the particle size of the catalyst after spray drying is 40-80μm; the drying conditions after catalyst formation are 100-130℃ for 4-7h, and the calcination conditions are 400-600℃ for 5-10h.

[0073] Example 1

[0074] A fluidized bed system for producing low-carbon olefins by hydrogenation of carbon dioxide includes a dilute phase settling section 204 of a fluidized bed reactor. The bottom of the dilute phase settling section 204 is connected to a dense phase reaction section 203 of the fluidized bed reactor. A catalyst circulation temperature controller 212 is provided outside the dense phase reaction section 203. The catalyst circulation temperature controller 212 is connected to the bottom of the dilute phase settling section 204 and the dense phase reaction section 203 of the fluidized bed reactor respectively through a circulating heat-extracting catalyst delivery pipe 208. A heat-extracting catalyst quantity control valve 214 is provided on the circulating heat-extracting catalyst delivery pipe 208 between the dense phase reaction section 203 and the catalyst circulation temperature controller 212.

[0075] In this embodiment, the bottom of the dilute phase settling section 204 of the fluidized bed reactor is connected to the dense phase section 217 of the fluidized bed regenerator via a catalyst delivery pipe 207, and the catalyst delivery pipe 207 is equipped with a catalyst quantity control valve 210.

[0076] In this embodiment, the top of the dense phase section 217 of the fluidized bed regenerator is connected to the dilute phase settling section 218 of the fluidized bed regenerator.

[0077] In this embodiment, the circulating heat-extracting catalyst delivery pipe 208 between the catalyst circulation temperature controller 212 and the heat-extracting catalyst quantity control valve 214 is connected to a regenerated catalyst delivery pipe 221, and the other end of the regenerated catalyst delivery pipe 221 is connected to the bottom of the dilute phase settling section 218 of the fluidized bed regenerator; a regenerated catalyst temperature controller 211 is provided on the regenerated catalyst delivery pipe 221.

[0078] In this embodiment, a regeneration air inlet 215 is provided at the bottom of the dense phase section 217 of the fluidized bed regenerator, and a regeneration air distributor 216 is provided above the regeneration air inlet 215.

[0079] In this embodiment, a regenerated flue gas outlet 220 is provided at the top of the dilute phase settling section 218 of the fluidized bed regenerator, and a gas-solid separator 219 of the dilute phase settling section of the regenerator is provided below the regenerated flue gas outlet 220.

[0080] In this embodiment, a carbon dioxide hydrogenation feedstock inlet 201 is provided at the bottom of the dense phase reaction section 203 of the fluidized bed reactor, and a carbon dioxide hydrogenation feed distributor 202 is provided above the carbon dioxide hydrogenation feedstock inlet 201.

[0081] In this embodiment, a carbon dioxide hydrogenation product outlet 206 is provided at the top of the dilute phase settling section 204 of the fluidized bed reactor, and a gas-solid separator 205 of the dilute phase settling section of the reactor is provided below the carbon dioxide hydrogenation product outlet 206.

[0082] In this embodiment, an even number of catalyst circulation temperature controllers 212 are provided on the outside of the fluidized bed reactor, and the catalyst circulation temperature controllers 212 are evenly distributed on the outside of the fluidized bed reactor.

[0083] A method for producing low-carbon olefins by hydrogenating carbon dioxide using the above system includes the following steps: mixing raw carbon dioxide and raw hydrogen in a volume ratio of 1:3 and pressurizing to 3 MPa, preheating to 280°C, then entering the dense phase reaction section of a fluidized bed reactor and adding a catalyst, and reacting at 280°C for 10 seconds to produce low-carbon olefins.

[0084] The method for preparing the catalyst includes the following steps:

[0085] (1) Dissolve 5 kg Fe(NO3)3·9H2O, 0.2 kg Cu(NO3)2·3H2O, 3.2 kg Ni(NO3)2·6H2O, and 0.04 kg Zr(NO3)4·5H2O in 20 kg of deionized water. After stirring evenly, add 0.05 kg sucrose and 0.2 kg PEG2000. Stir at 80 °C for 8 h to obtain a sol. Dry the sol at 120 °C for 10 h and then calcine at 480 °C for 8 h to obtain nano-metal oxides.

[0086] (2) Dissolve 92g La(NO3)3·6H2O and 4g KNO3 in 500g deionized water to obtain a modified solution. Age 1kg of nano ZSM-5 molecular sieve at 550℃ for 2h, then impregnate ZSM-5 molecular sieve with the modified solution, let stand for 12h, dry at 110℃ for 8h, and then calcine at 550℃ for 12h to obtain modified ZSM-5 molecular sieve.

[0087] (3) Disperse the nano-metal oxide obtained in step (1) and the modified ZSM-5 molecular sieve obtained in step (2) in 7 kg of deionized water, then add 100 g of ethanol and 300 g of silane coupling agent KH560, stir thoroughly, and then add 4 kg of aluminum sol with a solid content of 35% to obtain a slurry. Send the slurry into a spray drying tower and spray dry it under the conditions of furnace temperature of 400℃, outlet temperature of 150℃ and spray pressure of 3.0 MPa to obtain a shaped catalyst. Then dry the shaped catalyst at 130℃ for 7 h and then calcine it at 500℃ for 10 h to obtain the catalyst.

[0088] The reaction products enter the product separation system for product separation. After separation, the products are unreacted hydrogen and carbon dioxide, methane and ethane, ethylene and propylene, propane and C4 and C5+ hydrocarbons, and water.

[0089] Example 2

[0090] The apparatus and catalyst used in this embodiment are the same as those in Example 1. The difference lies in the preparation method, which includes the following steps: mixing raw carbon dioxide and raw hydrogen in a volume ratio of 1:5 and pressurizing to 4 MPa, preheating to 330°C, and then entering the dense phase reaction section of a fluidized bed reactor and adding a catalyst, reacting at 330°C for 10 seconds to prepare low-carbon olefins.

[0091] The reaction products enter the product separation system for product separation. After separation, the products are unreacted hydrogen and carbon dioxide, methane and ethane, ethylene and propylene, propane and C4 and C5+ hydrocarbons, and water.

[0092] Comparative Example 1

[0093] This comparative example is basically the same as Example 1, except that the device in this comparative example does not use the catalyst circulation temperature controller 212 to directly circulate the catalyst externally.

[0094] Comparative Example 2

[0095] This comparative example is basically the same as Example 1, except that the catalyst used in this comparative example is a conventional iron oxide catalyst.

[0096] By adding the same carbon dioxide and hydrogen feedstocks to the reactions of Examples 1-2 and Comparative Examples 1-2, the carbon dioxide hydrogenation products after the reaction were detected and analyzed. The results are shown in Tables 1-3.

[0097] Table 1 Comparison of CO2 conversion rates

[0098] Example 1 Example 2 Comparative Example 1 Comparative Example 2 CO2 conversion rate, % 40.9 42.4 29.8 31.2

[0099] Table 2 Comparison of Product Composition

[0100]

[0101] Table 3 Comparison of Relative Energy Consumption

[0102] Example 1 Example 2 Comparative Example 1 Comparative Example 2 relative energy consumption 0.89 0.91 1 0.93

[0103] As shown in Tables 1-3, the CO2 conversion rate of Examples 1-2 and Comparative Example 2 is higher than that of Comparative Example 1. The low-carbon olefins C2 generated in Examples 1-2 and Comparative Example 2... ＝ +C3 ＝ The proportion is higher than that of the low-carbon olefins C2 generated in Comparative Example 1. ＝ +C3 ＝ The proportion of energy consumption in Examples 1-2 and Comparative Example 2 is relatively lower than that in Comparative Example 1.

[0104] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for producing low-carbon olefins by hydrogenating carbon dioxide using a system, characterized in that, The system includes a dilute phase settling section (204) of a fluidized bed reactor. The bottom of the dilute phase settling section (204) is connected to the dense phase reaction section (203) of the fluidized bed reactor. A catalyst circulation temperature controller (212) is provided outside the dense phase reaction section (203) of the fluidized bed reactor. The catalyst circulation temperature controller (212) is connected to the bottom of the dilute phase settling section (204) and the dense phase reaction section (203) of the fluidized bed reactor respectively through a circulating heat-extracting catalyst delivery pipe (208). A heat-extracting catalyst quantity control valve (214) is provided on the circulating heat-extracting catalyst delivery pipe (208) between the dense phase reaction section (203) of the fluidized bed reactor and the catalyst circulation temperature controller (212). The preparation method includes the following steps: mixing raw carbon dioxide and raw hydrogen in a volume ratio of 1:(2-9) and pressurizing to 3-5 MPa, preheating to 250-400℃, and then entering the dense phase reaction section of a fluidized bed reactor and adding a catalyst, and reacting at a temperature of 250-400℃ for 5-15 seconds to prepare low-carbon olefins. The catalyst comprises 10-80 wt% nano-metal oxide and 20-90 wt% modified ZSM-5 molecular sieve. The nano-metal oxide and modified ZSM-5 molecular sieve are treated with a silane coupling agent, a binder is added to form a slurry, and finally the slurry is shaped by spray drying and then calcined to obtain the carbon dioxide hydrogenation catalyst. The nano-metal oxide includes component A and component B. Component A is selected from any three of iron oxide, cobalt oxide, molybdenum oxide, nickel oxide, and copper oxide, and component B is selected from any one of zirconium oxide, potassium oxide, and calcium oxide. The modified ZSM-5 molecular sieve includes component a, component b, and ZSM-5 molecular sieve. Component a is selected from either lanthanum oxide or cerium oxide, and component b is selected from either potassium oxide or magnesium oxide.

2. The preparation method according to claim 1, characterized in that, The bottom of the dilute phase settling section (204) of the fluidized bed reactor is connected to the dense phase section (217) of the fluidized bed regenerator through a catalyst delivery pipe (207), and the catalyst delivery pipe (207) is equipped with a catalyst quantity control valve (210).

3. The preparation method according to claim 2, characterized in that, The top of the dense phase section (217) of the fluidized bed regenerator is connected to the dilute phase settling section (218) of the fluidized bed regenerator.

4. The preparation method according to claim 3, characterized in that, The circulating heat-extracting catalyst delivery pipe (208) between the catalyst circulation temperature controller (212) and the heat-extracting catalyst quantity control valve (214) is connected to a regenerated catalyst delivery pipe (221), and the other end of the regenerated catalyst delivery pipe (221) is connected to the bottom of the dilute phase settling section (218) of the fluidized bed regenerator; a regenerated catalyst temperature controller (211) is provided on the regenerated catalyst delivery pipe (221).

5. The preparation method according to claim 3, characterized in that, The bottom of the dense phase section (217) of the fluidized bed regenerator is provided with a regeneration air inlet (215), and a regeneration air distributor (216) is provided above the regeneration air inlet (215).

6. The preparation method according to claim 3, characterized in that, The top of the dilute phase settling section (218) of the fluidized bed regenerator is provided with a regenerated flue gas outlet (220), and a gas-solid separator (219) of the dilute phase settling section of the regenerator is provided below the regenerated flue gas outlet (220).

7. The preparation method according to claim 1, characterized in that, The bottom of the dense phase reaction section (203) of the fluidized bed reactor is provided with a carbon dioxide hydrogenation feed inlet (201), and a carbon dioxide hydrogenation feed distributor (202) is provided above the carbon dioxide hydrogenation feed inlet (201).

8. The preparation method according to claim 1, characterized in that, The top of the dilute phase settling section (204) of the fluidized bed reactor is provided with a carbon dioxide hydrogenation product outlet (206), and a gas-solid separator (205) of the dilute phase settling section of the reactor is provided below the carbon dioxide hydrogenation product outlet (206).

9. The preparation method according to claim 1, characterized in that, The fluidized bed reactor is provided with an even number of catalyst circulation temperature controllers (212) on its exterior, and the catalyst circulation temperature controllers (212) are evenly distributed on the exterior of the fluidized bed reactor.

10. The preparation method according to claim 1, characterized in that, Component B accounts for 1–10% of the weight of the nano-metal oxide.

11. The preparation method according to claim 1, characterized in that, Component a accounts for 0.1-5% of the weight of the modified ZSM-5 molecular sieve, and component b accounts for 0.1-3% of the weight of the modified ZSM-5 molecular sieve.

12. The preparation method according to claim 1, characterized in that, The silane coupling agent is KH560 and / or KH570.

13. The preparation method according to claim 11, characterized in that, The binder is aluminum sol and / or silica sol.

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