Reaction system for preparing ethylene carbonate from carbon dioxide

Abstract

The invention provides a reaction system for preparing ethylene carbonate from carbon dioxide. The system comprises an EC reactor, a heat recovery unit, a circulating pump and an EC refining unit, the EC reactor comprises a reaction section, a heat exchange section and a liquid distributor. And uniform distribution of liquid in the reactor and timely heat removal in the reaction process are realized while high EC synthesis conversion rate is realized in the single tower. By adopting multifunctional advanced reaction equipment integrating a reactor, an external heat removal heat exchanger and a reaction distribution system into a whole, the occupied area of an EC reaction system is effectively reduced, the reaction temperature in the reactor is efficiently and stably controlled, and the equilibrium conversion rate of the whole EC synthesis reaction can be improved by controlling the equilibrium temperature of the tail section of the reactor; the conversion per pass of EO can reach 99% or above; circulating material lines are arranged at outlets of the first reaction section, the second reaction section and the third reaction section of the reactor, and reaction materials cooled among the reactor sections are circulated to an inlet of the reactor, so that the temperature rise rate in the reaction is reduced, the temperature runaway phenomenon of the reactor is avoided, meanwhile, the EO concentration in fed materials is diluted, and the production safety of the reactor is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and in particular relates to a reaction system for preparing ethylene carbonate from carbon dioxide. Background Art

[0002] Ethylene carbonate is an important organic chemical raw material, widely used in fertilizer, fiber, pharmaceutical and organic synthesis fields. At the same time, electronic grade ethylene carbonate can be used as a solvent for lithium-ion batteries and has a very wide application market. The production and synthesis processes of ethylene carbonate mainly include phosgene synthesis, ester exchange, halogenated alcohol, direct oxidation of ethylene and carbon dioxide, esterification of ethylene oxide and carbon dioxide, and urea alcoholysis. Among them, the method of synthesizing ethylene carbonate by esterification of ethylene oxide (EO) and CO2 as raw materials has been widely studied and applied because it can effectively utilize CO2 raw materials and produce ethylene glycol as a by-product. While realizing the resource utilization of CO2, it produces high value-added ethylene carbonate products.

[0003] The esterification reaction of ethylene oxide (EO) and CO2 is an exothermic reaction, and the reaction pressure is generally high. The study of this reaction system is a key part of the entire EC synthesis process. At present, the types of EC synthesis reactors studied include tower reactors, kettle reactors, fixed bed reactors, radial reactors, etc. In the current industrial devices, the reaction system uses multiple empty tower reactors in series, and heat removal equipment is set between the sections.

[0004] Patent CN112876449B proposes a continuous production method and system for cyclic carbonates, wherein the carbonate reaction system adopts a plurality of reactors connected in series for synthesis reaction, which has the problems of a large number of equipment and a large floor area; Patent CN111013496A proposes a packed tower reactor and a production method for producing cyclic carbonates, wherein a single-stage packed tower reactor is adopted for EC synthesis reaction, wherein a packing is arranged in the reactor, which increases the pressure drop of the reactor, and heat exchange dead zone is easily present, and a single-stage reaction is adopted, and the reaction conversion rate is low; Patent CN111072623A proposes a method for preparing ethylene carbonate by a circulating jet mixing method, wherein a single container reactor is adopted in combination with an external circulating heat removal device to realize EC synthesis reaction, but external heat removal is required, the number of equipment is large, and the reaction conversion rate is low; Patent CN212882379U proposes an ethylene carbonate synthesis production device, wherein two reactors are connected in series for EC synthesis reaction, and an external heat removal method is adopted for reaction heat removal, and the reactor has the problems of a large floor area for the reactor and a large number of reaction equipment.

[0005] Therefore, there is an urgent need for a new carbon dioxide to ethylene carbonate reaction system with a small reaction zone footprint, controllable reaction system temperature, high energy utilization efficiency, strong reaction safety and high reaction conversion rate to replace the existing process technology. Summary of the invention

[0006] In order to solve the above problems in the prior art, the present invention proposes a reaction system for preparing ethylene carbonate from carbon dioxide. The reaction system can meet the process design requirements, has the characteristics of small reaction area, controllable reaction system temperature, high energy utilization efficiency, strong reaction safety and high reaction conversion rate.

[0007] The present invention provides a reaction system for preparing ethylene carbonate from carbon dioxide, which comprises an EC reactor, a heat recovery unit, a circulation pump and an EC refining unit;

[0008] The EC reactor is used for EC synthesis reaction, reaction heat removal, and uniform liquid distribution;

[0009] The heat recovery unit uses a heat exchange medium to remove heat and recover energy from the materials in the reactor;

[0010] The EC refining unit purifies and separates the EC crude liquid from the EC reactor.

[0011] As a specific embodiment of the present invention, the EC reactor includes an EC synthesis reaction section, a heat exchange section and a liquid distributor.

[0012] As a specific embodiment of the present invention, the EC synthesis reaction section is a reaction area for EC synthesis reaction, and the EC synthesis reaction section includes 1 to 6 sections.

[0013] As a specific embodiment of the present invention, the EC synthesis reaction section has an operating pressure of 1.0 MPaG to 10.0 MPaG and an operating temperature of 50° C. to 250° C.;

[0014] The feeding position of the CO2 includes mixed feeding from a pipeline and direct feeding into an EC reactor; the feeding phase of the CO2 includes liquid phase and gas phase;

[0015] The directions of the reactant materials in and out of the EC reactor include bottom-in and top-out, and top-in and bottom-out.

[0016] As a specific embodiment of the present invention, the heat exchange section of the EC reactor is an EC synthesis reaction heat removal section, and the heat exchange section includes 1 to 6 sections.

[0017] As a specific embodiment of the present invention, the heat removal structure type of the heat exchange section includes heat removal inside the coil, heat removal outside the coil, heat removal by jacket, and heat removal by tube in tube.

[0018] As a specific embodiment of the present invention, the liquid distributor of the EC reactor is located at the inlet of the EC reactor or in the EC reactor; the liquid distributor is used for uniform distribution of liquid, and the liquid distributor includes 1 to 6 liquid distributors.

[0019] As a specific embodiment of the present invention, the heat recovery unit uses a reasonable heat exchange medium to remove heat from the materials in the reactor and recover energy at the same time; the heat exchange medium includes heat transfer oil, boiler water, warm water, circulating water, and organic power generation medium.

[0020] As a specific embodiment of the present invention, a reaction intermediate material return pipeline is also arranged between the EC synthesis reactor sections to circulate the reaction intermediate material after cooling between the reactor sections to the EC reactor inlet; so as to reduce the temperature rise rate in the reactor, avoid reactor temperature runaway, and dilute the EO concentration in the feed, thereby improving the production safety of the reactor.

[0021] As a specific embodiment of the present invention, the circulation pump provides power for the reaction intermediate material return pipeline.

[0022] As a specific embodiment of the present invention, the reaction intermediate material return line is located at the extraction position between the reactor sections, including the outlets of reaction sections 1-6; specifically, the outlet of reaction section 1, the outlet of reaction section 2, the outlet of reaction section 3, the outlet of reaction section 4, the outlet of reaction section 5, and the outlet of reaction section 6; the circulation rate of the reaction intermediate material is 5wt% to 90wt%.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The reaction system for preparing ethylene carbonate from carbon dioxide of the present invention adopts a single reactor, and a reaction section, a heat exchange section and a liquid distributor are arranged inside the reactor to ensure that a high synthesis conversion rate of EC is achieved in a single tower, and at the same time, a uniform distribution of liquid in the reactor and timely heat removal during the reaction process are achieved.

[0025] 2. The carbon dioxide to ethylene carbonate reaction system of the present invention effectively reduces the footprint of the EC reaction system by adopting a multifunctional advanced reaction device that integrates a reactor, an external heat removal heat exchanger and a reaction distribution system, efficiently and stably controls the reaction temperature in the reactor, and can improve the equilibrium conversion rate of the entire EC synthesis reaction by controlling the equilibrium temperature of the final stage of the reactor.

[0026] 3. In the reaction system for preparing ethylene carbonate from carbon dioxide of the present invention, the logistics return line refers to a circulating reaction intermediate material line set at the outlet of the first, second and third reaction stages of the reactor, so that the reaction intermediate material after inter-stage cooling in the reactor is circulated to the reactor inlet, thereby reducing the temperature rise rate in the reaction, avoiding the reactor temperature runaway phenomenon, and at the same time diluting the EO concentration in the feed, thereby improving the safety of reactor production.

[0027] 4. The reaction system of carbon dioxide to ethylene carbonate of the present invention, wherein the heat recovery unit refers to a method of removing heat from the outside of the reactor, using a reasonable heat exchange medium to remove heat from the materials in the reactor, and recovering energy at the same time. The medium used in the heat recovery system includes but is not limited to heat transfer oil, boiler water, warm water, circulating water, organic power generation medium, etc., and the energy utilization efficiency of the entire EC reaction system is improved by reasonably recycling the medium and low temperature heat in the reactor;

[0028] 5. The reaction system for preparing ethylene carbonate from carbon dioxide of the present invention can achieve an EO single-pass conversion rate of more than 99%, and has the characteristics of small footprint of the reaction zone, controllable temperature of the reaction system, high energy utilization efficiency, strong reaction safety and high reaction conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a process flow chart of a novel reaction system for preparing ethylene carbonate from carbon dioxide in Example 1 of the present invention (flow direction from bottom to top);

[0030] Among them, 1-EC reactor, 1-1-liquid distributor section 1, 1-2-reaction section 1, 1-3-heat exchange section 1, 1-4-liquid distributor section 2, 1-5-reaction section 2, 1-6-heat exchange section 2, 1-7-liquid distributor section 3, 1-8-heat exchange section 3, 1-9-reaction section 3; 2-heat recovery system; 3-circulation pump; 4-EC refining unit;

[0031] Figure 2 This is a process flow chart of a novel reaction system for preparing ethylene carbonate from carbon dioxide in Example 2 of the present invention (upper inlet and lower outlet flow direction);

[0032] Among them, 1-EC reactor, 1-1-liquid distributor section 1, 1-2-reaction section 1, 1-3-heat exchange section 1, 1-4-liquid distributor section 2, 1-5-reaction section 2, 1-6-heat exchange section 2, 1-7-liquid distributor section 3, 1-8-heat exchange section 3, 1-9-reaction section 3; 2-heat recovery system; 3-circulation pump; 4-EC refining unit;

[0033] Figure 3 This is the process flow of a novel reaction system for preparing ethylene carbonate from carbon dioxide according to Example 3 of the present invention;

[0034] Among them, 1-EC reactor, 1-1-liquid distributor section 1, 1-2-reaction section 1, 1-3-heat exchange section 1, 1-4-liquid distributor section 2, 1-5-reaction section 2, 1-6-heat exchange section 2, 1-7-liquid distributor section 3, 1-8-heat exchange section 3, 1-9-reaction section 3; 2-heat recovery system; 3-circulation pump; 4-EC refining unit;

[0035] Figure 4 This is a process flow chart of a novel reaction system for preparing ethylene carbonate from carbon dioxide according to Example 4 of the present invention;

[0036] Among them, 1-EC reactor, 1-1-liquid distributor section 1, 1-2-reaction section 1, 1-3-heat exchange section 1, 1-4-liquid distributor section 2, 1-5-reaction section 2, 1-6-heat exchange section 2, 1-7-liquid distributor section 3, 1-8-heat exchange section 3, 1-9-reaction section 3; 2-heat recovery system; 3-circulation pump; 4-EC refining unit;

[0037] Figure 5 This is a process flow chart of a novel reaction system for preparing ethylene carbonate from carbon dioxide in Example 5 of the present invention (upper inlet and lower outlet flow direction);

[0038] Among them, 1-EC reactor, 1-1-liquid distributor section 1, 1-2-reaction section 1, 1-3-heat exchange section 1, 1-4-liquid distributor section 2, 1-5-reaction section 2, 1-6-heat exchange section 2, 1-7-liquid distributor section 3, 1-8-heat exchange section 3, 1-9-reaction section 3; 2-heat recovery system; 3-circulation pump; 4-EC refining unit. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0040] Example 1

[0041] This embodiment provides a reaction system for preparing ethylene carbonate from carbon dioxide, and the specific details are as follows:

[0042] Combination Figure 1 , Figure 2The specific process of the novel reaction system for preparing ethylene carbonate from CO2 is as follows: the raw material ethylene oxide is mixed with fresh catalyst, circulating catalyst, circulating material and fresh CO2 and then sent to the EC reactor (1), and an EC synthesis reaction section, a liquid distributor and a heat exchange section are set in the reactor. A heat recovery system (2) is used to provide a heat exchange medium to remove the heat of the reaction from the EC reactor. At the same time, a logistics return line is set at the outlet of the first reaction section and the outlet of the second reaction section, and the circulation pump (3) is used to pressurize and return to the inlet of the EC reactor. The EC mixture after the reaction is sent to the EC refining unit (4), the EC product is refined and separated, and after part of the waste catalyst is discharged, the remaining catalyst is recycled.

[0043] The feeding position of fresh CO2 can be mixed from the pipeline or directly fed into the EC reactor. The feeding phase of fresh CO2 is liquid phase or gas phase.

[0044] The EC reactor is a single reaction equipment for EC synthesis that integrates a reaction section, a heat exchange section and a liquid distributor. The operating pressure is 1.0MPaG to 10.0MPaG, the operating temperature is 50℃ to 250℃, and the specific number of reaction sections is 2;

[0045] The direction of the reaction materials in the EC reactor is from bottom to top. Figure 1 As shown, or it can be up-in and down-out, such as Figure 2 As shown;

[0046] Liquid distributors (1-1, 1-4, 1-9) are internal parts of the equipment used for uniform distribution of liquid at the reactor inlet or in the reactor, and the number of liquid distributors provided is 1-6 according to the working conditions;

[0047] The heat exchange sections (1-3, 1-6, 1-9) refer to the reaction heat removal sections set in the EC reactor, which use a reasonable heat exchange medium to remove the reaction heat in time, and the heat exchange sections are set to sections 1-6;

[0048] The heat removal structure types of the heat exchange sections (1-3, 1-6, 1-9) include but are not limited to heat removal inside the coil, heat removal outside the coil, heat removal by jacket, heat removal by tube in tube, etc.;

[0049] The heat recovery system (2) is a system that uses a reasonable heat exchange medium to remove heat from the materials in the reactor and recover energy at the same time. The heat exchange medium used in the heat recovery system is selected from thermal oil, boiler water, warm water, circulating water, and organic power generation medium.

[0050] The logistics return line refers to circulating the intermediate reaction materials after cooling between reactor sections to the reactor inlet to reduce the temperature rise rate in the reactor, avoid reactor temperature runaway, and dilute the EO concentration in the feed to improve the production safety of the reactor;

[0051] The extraction positions of the reaction intermediate material return line between the reactor sections are the outlet of the first reaction section, the outlet of the second reaction section, the outlet of the third reaction section, the outlet of the fourth reaction section, the outlet of the fifth reaction section, and the outlet of the sixth reaction section, and the circulation ratio is 5-90wt%;

[0052] The EC refining unit (3) is used to purify and separate the EC crude liquid from the reactor to obtain EC products, and to recycle the catalyst.

[0053] Example 2

[0054] According to the technical solution in Example 1, this embodiment changes the heat exchange type of the reaction heat exchange section (1-3, 1-6, 1-9) to a shell-and-tube heat exchange, and its process flow chart is as follows: Figure 3 shown.

[0055] Figure 3 The core difference of the process flow is that the shell-and-tube heat exchange structure is used to remove the reaction heat. A shell-and-tube heat exchange section is set inside the reactor, and the reaction materials go to the tube side and the heat exchange medium goes to the shell side to remove the reaction heat and control the reaction temperature. The characteristics of this process are that the heat exchange efficiency of the entire reaction heat removal system is better, which is conducive to the timely removal of reaction heat and the reaction temperature is easier to control. It is an optimal alternative.

[0056] Example 3

[0057] According to the technical solution in Example 1, the heat exchange type of the reaction heat exchange section (1-3, 1-6, 1-9) is changed to jacket heat removal in this embodiment, and the process flow chart is as follows: Figure 4 shown.

[0058] Figure 4 The core difference of the process flow is that the jacket structure is used to remove the reaction heat. A jacket is set outside the reactor, the reaction materials flow in the reactor, and the heat exchange medium is exchanged in the jacket to remove the reaction heat and control the reaction temperature. The characteristics of this process are that the entire reaction heat removal system is simpler and the reactor pressure drop is smaller, which is a preferred alternative.

[0059] Example 4

[0060] Taking the new reaction system process of carbon dioxide to ethylene carbonate (bottom-in and top-out flow direction) with internal coil heat removal as an example, the process flow Figure 5 As shown below:

[0061] This embodiment is designed by taking a 100,000 tons / year scale EC reaction system as an example. Fresh EO raw material (5.0-7.5 t / h) is mixed with fresh EC catalyst, circulating catalyst and reactor circulating flow and then enters from the bottom of EC reactor (1). Fresh CO2 raw material (5.0-7.5 t / h) can be fed directly into EC reactor (1) together with EO mixed material, or it can be fed into EC reactor (1) alone from the bottom. The feed phase of fresh CO2 raw material includes but is not limited to liquid and gaseous. After the reaction raw material enters the EC reactor (1), a liquid distributor (1-1) is set at the reactor inlet to evenly distribute the reaction feed, and then a homogeneous EC synthesis reaction is carried out. In a reaction section, a heat exchange section (1-3) using an internal coil to remove heat is set to remove the reaction heat during the reaction process. After the first stage reaction, the reaction liquid is redistributed by the second stage (1-4) of the liquid distributor and enters the second stage (1-5) of the reaction for the second stage. In the second stage, a heat exchanger second stage (1-6) is provided to remove the heat of the reaction process by using an internal coil. After the second stage reaction, the reaction liquid is redistributed by the third stage (1-7) of the liquid distributor and enters the third stage (1-8) of the reaction for the third stage. In the third stage, a heat exchanger third stage (1-9) is provided to remove the heat of the reaction process by using an internal coil. The operating pressure of the entire reactor includes but is not limited to 1.0 MPaG to 10.0 MPaG, and the operating temperature includes but is not limited to 50°C to 250°C. Material return lines are provided at the outlets of the first and second stages of the reaction in the reactor to return part of the reacted material to the reaction inlet, and the circulation ratio thereof includes but is not limited to 5% to 90%. The reaction liquid at the outlet of the reactor enters the EC refining unit for product separation, and the EC product is obtained after refining, and the catalyst is circulated. In the heat recovery system (2), this case uses a heat recovery method that uses comprehensive heat exchange of boiler water, warm water, and organic power generation medium to utilize energy. For the reaction section with higher temperature in the reactor (140-250°C), boiler water is used as the medium to produce low-pressure steam as a by-product. For the reaction section with lower temperature in the reactor (80-140°C), warm water is used as the medium to recover the heat, and the obtained warm water is used for insulation and heating of the EC device. When the reaction heat is large, organic power generation medium can also be used in conjunction with an organic Rankine power generation system to recover heat and generate electricity. By setting up a reaction heat recovery system, the energy utilization efficiency of the entire EC reaction system can be effectively improved.

[0062] In summary, the carbon dioxide to ethylene carbonate reaction system of the present invention replaces the existing process technology. A single EC reactor is used, and a reaction section, a heat exchange section and a liquid distributor are arranged inside the reactor to ensure that a high EC synthesis conversion rate is achieved in a single tower while achieving uniform distribution of the liquid in the reactor and timely heat removal during the reaction process. By adopting a multifunctional advanced reaction equipment that integrates the reactor, the external heat removal heat exchanger and the reaction distribution system, the footprint of the EC reaction system is effectively reduced, the reaction temperature in the reactor is efficiently and stably controlled, and the equilibrium conversion rate of the entire EC synthesis reaction can be improved by controlling the equilibrium temperature of the reactor terminal. A circulating material line is set at the outlet of the first, second and third reaction sections of the reactor, and the reaction material cooled between the reactor sections is circulated to the reactor inlet, thereby reducing the temperature rise rate in the reaction, avoiding the reactor temperature rise phenomenon, and diluting the EO concentration in the feed, thereby improving the safety of reactor production. Compared with the existing technology, the present invention can achieve an EO single-pass conversion rate of more than 99%, and has the characteristics of a small footprint in the reaction zone, controllable temperature of the reaction system, high energy utilization efficiency, strong reaction safety and high reaction conversion rate.

[0063] Any numerical value mentioned in the present invention, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​from the minimum value to the maximum value each time increasing by one unit. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0064] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A reaction system for preparing ethylene carbonate from carbon dioxide, characterized in that: The system includes an EC reactor, a heat recovery unit, a circulation pump and an EC refining unit; The EC reactor is used for EC synthesis reaction, reaction heat removal, and uniform liquid distribution; The heat recovery unit uses a heat exchange medium to remove heat and recover energy from the materials in the reactor; The EC refining unit purifies and separates the EC crude liquid from the EC reactor.

2. The reaction system according to claim 1, characterized in that: The EC reactor comprises an EC synthesis reaction section, a heat exchange section and a liquid distributor.

3. The reaction system according to claim 1 or 2, characterized in that: The EC synthesis reaction section is a reaction area for EC synthesis reaction, and the EC synthesis reaction section includes 1 to 6 sections.

4. The reaction system according to any one of claims 1 to 3, characterized in that: The EC synthesis reaction section has an operating pressure of 1.0 MPaG to 10.0 MPaG and an operating temperature of 50°C to 250°C; The feeding position of the CO2 includes mixed feeding from a pipeline and direct feeding into an EC reactor; the feeding phase of the CO2 includes liquid phase and gas phase; The directions of the reactant materials in and out of the EC reactor include bottom-in and top-out, and top-in and bottom-out.

5. The reaction system according to any one of claims 1 to 4, characterized in that: The heat exchange section of the EC reactor is a heat removal section for heat from the EC synthesis reaction, and the heat exchange section includes sections 1 to 6.

6. The reaction system according to any one of claims 1 to 5, characterized in that: The heat removal structure types of the heat exchange section include heat removal inside the coil, heat removal outside the coil, heat removal by jacket, and heat removal by tube in tube.

7. The reaction system according to any one of claims 1 to 6, characterized in that: The liquid distributor of the EC reactor is located at the inlet of the EC reactor or in the EC reactor; the liquid distributor is used for uniform distribution of liquid, and the number of the liquid distributors is 1 to 6.

8. The reaction system according to any one of claims 1 to 7, characterized in that: The heat exchange medium includes heat transfer oil, boiler water, warm water, circulating water, and organic power generation medium.

9. The reaction system according to any one of claims 1 to 8, characterized in that: A reaction intermediate material return pipeline is also arranged between the EC synthesis reactor sections to circulate the reaction intermediate material cooled between the reactor sections to the EC reactor inlet; the circulation pump provides power for the reaction intermediate material return pipeline.

10. The reaction system according to claims 1-9, characterized in that: The reaction intermediate material return line is located at the extraction position between the reactor sections, including the outlets of reaction sections 1-6; the reaction intermediate material circulation rate is 5wt% to 90wt%.

Images