Method and system for preparing ethylene carbonate

Abstract

The invention relates to the technical field of preparation of ethylene carbonate, and discloses a method and a system for preparing ethylene carbonate. The method comprises the following steps: in the presence of a solid catalyst, ethylene, O2 and CO2 are subjected to a reaction, the molar ratio of ethylene to O2 to CO2 is 1: (0.8-5): (4-20), the solid catalyst comprises a carrier, an active component and a halogen-containing compound, the active component and the halogen-containing compound are loaded on the carrier, and the active component is silver. According to the method disclosed by the invention, the ethylene carbonate is synthesized from ethylene, O2 and CO2 in one step in the same fixed bed reactor by adopting a continuous synthesis process, and the selectivity of the ethylene carbonate is relatively high.

Description

Technical Field

[0001] The invention relates to the technical field of ethylene carbonate preparation, and in particular to a method and system for preparing ethylene carbonate. Background Art

[0002] Ethylene carbonate is an important cyclic organic carbonate product in the new energy field. It has the advantages of low toxicity, high boiling point and good stability. It is widely used in key industries such as special environmentally friendly battery fluids and biodegradable materials. It is also used in the production of high-end chemical products such as dimethyl carbonate and ethylene glycol.

[0003] At present, my country's ethylene carbonate synthesis process faces the following technical difficulties: (1) The phosgene method is accompanied by the generation of a large amount of HCl, which causes serious corrosion to equipment and has been eliminated; (2) The traditional urea alcoholysis method uses ethylene glycol as raw material, and low-temperature synthesis is limited by thermodynamics, while high-temperature conditions have high energy consumption; (3) The carbon dioxide-ethylene oxide cycloaddition method is the most widely used, but the raw material ethylene oxide is expensive, and its separation, purification, storage and transportation costs are also high. In addition, ethylene oxide is flammable and explosive, and the safety risk is relatively large. How to reduce the energy consumption and pollution of ethylene carbonate synthesis and improve the process economy and environmental protection are major problems that need to be urgently solved in this industry. In view of the above technical difficulties, it is urgent to develop a new generation of low-energy, high-efficiency, and environmentally friendly ethylene carbonate synthesis technology.

[0004] The continuous reaction process of synthesizing ethylene carbonate directly from ethylene with oxygen and carbon dioxide belongs to the new generation of ethylene carbonate synthesis technology. This technical route adopts a one-step continuous reaction process, which significantly simplifies the process, eliminates the separation, purification, storage and transportation of ethylene oxide, significantly reduces process energy consumption, and improves the economy and safety of the whole process. In addition, the whole process generates nearly zero waste. After ethylene is epoxidized to generate ethylene oxide, it is immediately cycloadded with carbon dioxide to generate ethylene carbonate, which solves the problems of poor selectivity of ethylene oxide synthesis, high separation cost and high risk of explosion in storage and transportation, as well as the high energy consumption of urea alcoholysis, poor intrinsic safety of epoxidation and cycloaddition reactions and complex processes.

[0005] Patent application CN114768694A discloses a device for preparing ethylene carbonate and a process thereof, which realizes the synthesis of ethylene carbonate by epoxidation of ethylene and cycloaddition of ethylene oxide and carbon dioxide in series. However, the device is actually used to synthesize ethylene carbonate in two steps, firstly oxidizing ethylene into ethylene oxide under epoxidation conditions, and then synthesizing ethylene carbonate by reacting the obtained ethylene oxide with carbon dioxide under the action of a catalyst.

[0006] Patent application CN112480058A discloses a production system for directly preparing cyclic carbonate from olefins and its application, wherein olefins, oxygen and carbon dioxide are mixed and fed from the lower part of the reactor side wall, and a homogeneous composite catalyst is fed from the upper part of the reactor side wall, so that olefin epoxidation to epoxide and epoxide and carbon dioxide cycloaddition to synthesize cyclic carbonate in series are realized in the same reactor. However, it can be concluded from the embodiments that the system is mainly used for directly synthesizing styrene carbonate from styrene and carbon dioxide. In addition, since the reaction raw materials are all fed from the lower part of the reactor side wall, it is not suitable for gaseous olefin reactions such as ethylene and propylene because of easy flooding.

[0007] Patent application CN106966862B discloses a method for preparing propylene glycol and propylene carbonate simultaneously. The method is divided into two steps. First, propylene is oxidized to propylene oxide under epoxidation conditions, and then the obtained propylene oxide, water, carbon dioxide and another catalyst are contacted to synthesize propylene carbonate. The method adopts an intermittent reaction process and is divided into two steps. The process conditions need to be switched, which is time-consuming and labor-intensive. Although there is no need to separate and purify propylene oxide, the process is still relatively complicated. Summary of the invention

[0008] The object of the present invention is to provide a method and system for preparing ethylene carbonate by continuous reaction, in which ethylene, O 2 With CO 2 The direct continuous reaction to synthesize ethylene carbonate significantly simplifies the process, eliminates the steps of separation, purification, storage and transportation of ethylene oxide, and improves production efficiency through continuous production; significantly reduces process energy consumption and improves the economy of the entire process; the one-step direct synthesis has the same process conditions throughout the entire process, avoiding the problem of switching process conditions caused by different process conditions in the two-step method; and the solid catalyst used in the reaction process is easy to separate, solving the limitations of difficult separation and high cost of homogeneous catalysts; the preparation system is simple, which significantly reduces equipment investment.

[0009] In order to achieve the above object, the present invention provides a method for preparing ethylene carbonate, which comprises: reacting ethylene, O 2 and CO 2 Reaction, wherein ethylene, O 2 and CO 2 The molar ratio of is 1:(0.8-5):(4-20), the solid catalyst comprises a carrier and an active component and a halogen-containing compound loaded on the carrier, wherein the active component is silver.

[0010] Preferably, in the solid catalyst, the content of the active component is 0.1-5 parts by weight, preferably 1-4 parts by weight, relative to 100 parts by weight of the carrier; the content of the halogen-containing compound in terms of halogen element is 0.1-5 parts by weight, preferably 1-3 parts by weight.

[0011] Preferably, the carrier is a catalyst carrier capable of providing acid and base active sites.

[0012] Preferably, the carrier is selected from at least one of a molecular sieve and a metal oxide.

[0013] Preferably, the molecular sieve is TS-1 titanium silicalite molecular sieve.

[0014] Preferably, the metal oxide is aluminum oxide, magnesium oxide, zinc oxide and mixed metal oxides thereof.

[0015] Preferably, the halogen-containing compound is butylammonium bromide, propylammonium bromide, ZnBr 2 , KBr and KI.

[0016] Preferably, the reaction temperature is 160-250°C.

[0017] Preferably, the reaction is carried out in a fixed bed reactor.

[0018] Preferably, the outlet pressure of the fixed bed reactor is 0.1-1 MPa, and the feed space velocity is 2000-12000 mL / (g cat h).

[0019] Preferably, ethylene, O 2 and CO 2 After being mixed in the gas mixing unit, the gases enter the fixed bed reactor for reaction.

[0020] Preferably, the method further comprises: performing gas-liquid separation on the reaction product of the fixed bed reactor, and returning the separated gas phase component to the gas mixing unit and / or the fixed bed reactor for recycling.

[0021] A second aspect of the present invention provides a system for preparing ethylene carbonate, the system comprising:

[0022] The raw gas supply unit is used to supply ethylene, O 2 and CO 2 ;

[0023] A gas mixing unit for mixing ethylene, O 2 and CO 2 Mixing is performed;

[0024] A fixed bed reactor filled with a solid catalyst, through which the mixed gas from the gas mixing unit is reacted, wherein the solid catalyst comprises a carrier and an active component and a halogen-containing compound supported on the carrier;

[0025] A gas-liquid separation unit, used for performing gas-liquid separation on the reaction product of the fixed bed reactor;

[0026] The raw gas circulation unit is used to return the gas phase components separated in the gas-liquid separation unit to the gas mixing unit and / or the fixed bed reactor for recycling.

[0027] Compared with the prior art, the method and system for preparing ethylene carbonate of the present invention have the following advantages:

[0028] (1) The present invention adopts a continuous synthesis process to synthesize ethylene, O 2 With CO 2 One-step conversion to ethylene carbonate with high selectivity for ethylene carbonate;

[0029] (2) The solid catalyst used in the present invention is easy to separate and reuse, and the overall cost is low;

[0030] (3) In the present invention, ethylene carbonate can be directly synthesized in one reactor, while in the prior art, the reaction generally needs to be carried out in two steps, and the two steps use different catalysts and different reaction conditions, and different reaction conditions need to be switched;

[0031] (4) Compared with the traditional two-step method for synthesizing ethylene carbonate, the method of the present invention significantly simplifies the process, eliminates the steps of separation, purification, storage and transportation of ethylene oxide, significantly reduces process energy consumption, and improves the economic efficiency of the entire process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of an embodiment of a system for preparing ethylene carbonate by continuous reaction provided by the present invention;

[0033] Figure 2 It is a schematic diagram of another embodiment of the system for preparing ethylene carbonate by continuous reaction provided by the present invention.

[0034] Description of Reference Numerals

[0035] 1. Gas mixing unit; 2. Fixed bed reactor; 3. Gas-liquid separation unit; 4. Raw gas circulation unit. DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0037] The method for preparing ethylene carbonate of the present invention comprises: in the presence of a solid catalyst, reacting ethylene, O 2 and CO 2 to react.

[0038] In the method described in the present invention, ethylene, O 2 and CO 2 The molar ratio is 1:(0.8-5):(4-20), preferably 1:(0.9-2):(4-10).

[0039] In the method of the present invention, the solid catalyst comprises a carrier and an active component and a halogen-containing compound supported on the carrier, wherein the active component is silver.

[0040] In the solid catalyst, the content of the active component can be 0.1-5 parts by weight, preferably 1-4 parts by weight, relative to 100 parts by weight of the carrier. For example, it can be 1 part by weight, 1.3 parts by weight, 1.5 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.3 parts by weight, 2.5 parts by weight, 2.8 parts by weight, 3 parts by weight, 3.2 parts by weight, 3.5 parts by weight, 3.7 parts by weight or 4 parts by weight.

[0041] In the solid catalyst, the content of the halogen-containing compound is calculated as halogen content. Relative to 100 parts by weight of the carrier, the content of the halogen-containing compound in terms of halogen element can be 0.1-5 parts by weight, preferably 1-3 parts by weight, and specifically, for example, can be 1 part by weight, 1.2 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.4 parts by weight, 2.5 parts by weight, 2.7 parts by weight, 2.8 parts by weight or 3 parts by weight.

[0042] In the present invention, the carrier may be a catalyst carrier conventionally used in the art. Preferably, the carrier is a catalyst carrier capable of providing acid and base active sites. Further preferably, the carrier is at least one of a molecular sieve and a metal oxide.

[0043] In the present invention, the molecular sieve may be a titanium silicalite molecular sieve having a multi-level pore structure (such as micropores and mesopores). In a preferred embodiment, in order to obtain a higher selectivity for ethylene carbonate, the molecular sieve is a TS-1 titanium silicalite molecular sieve.

[0044] In the present invention, the metal oxide may be aluminum oxide, magnesium oxide, zinc oxide, and mixed metal oxides thereof. The mixed metal oxide may be, for example, magnesium aluminum hydrotalcite and / or zinc magnesium aluminum hydrotalcite.

[0045] In the present invention, the halogen-containing compound may be butylammonium bromide, propylammonium bromide, ZnBr 2 In a preferred embodiment, the halogen-containing compound is ZnBr 2 , KBr and KI.

[0046] In a preferred embodiment, the solid catalyst comprises a carrier and an active component and a halogen-containing compound supported on the carrier, wherein the carrier is magnesium aluminum hydrotalcite, the active component is silver, and the halogen-containing compound is ZnBr 2 , KBr and KI. The method for preparing the solid catalyst according to this preferred embodiment may include: immersing the magnesium aluminum hydrotalcite in a solution containing an active component precursor (such as silver nitrate), then sequentially placing it in a dark place, drying it and reducing it to obtain a catalyst intermediate; then placing the catalyst intermediate in a halogen compound aqueous solution, stirring, filtering, washing and drying it to obtain the solid catalyst.

[0047] In the method described in the present invention, ethylene, O 2 and CO 2 The reaction temperature for preparing ethylene carbonate is preferably 150-260°C, more preferably 180-230°C.

[0048] In the method described in the present invention, ethylene, O 2 and CO 2 The reaction process for preparing ethylene carbonate is preferably carried out in a fixed bed reactor. In this case, the solid catalyst is loaded in the fixed bed reactor as a catalyst bed. In the actual operation process, ethylene, O 2 and CO 2 The mixed gas passes through the catalyst bed in the fixed bed reactor from top to bottom.

[0049] When the reaction is carried out in a fixed bed reactor, the outlet pressure of the fixed bed reactor may be 0.1-1 MPa, and the feed space velocity may be 2000-12000 mL / (g cat h). In the present invention, pressure refers to absolute pressure.

[0050] In the method of the present invention, preferably, ethylene, O 2 and CO 2 After being mixed in the gas mixing unit, the gases enter the fixed bed reactor for reaction.

[0051] In the present invention, the gas mixing unit may be a static gas mixer or a shell-and-tube gas mixer.

[0052] When the gas mixing unit is a static gas mixer, the gas mixing process can be as follows: O 2 and CO 2 are first mixed in a first static gas mixer according to a certain ratio, and the formed mixed gas is then mixed with ethylene in a second static gas mixer according to a certain ratio to achieve the uniform mixing of ethylene, O 2 and CO 2 . Among them, the pressures in the first static gas mixer and the second static gas mixer can be 0.1 - 1 MPa.

[0053] When the gas mixing unit is a shell-and-tube gas mixer (where the tubes are oxygen permeable membranes), the gas mixing process can be as follows: CO 2 and ethylene are mixed in a pipeline according to a certain ratio and then enter the shell side of the shell-and-tube gas mixer, and oxygen enters the tube side of the shell-and-tube gas mixer. There is a positive pressure drop from the tube side to the shell side, and oxygen permeates through the membrane tubes into the shell side due to the pressure drop to achieve the mixing with ethylene and CO 2 . The permeation rate and permeation amount of oxygen are adjusted by the pressure drop. Among them, the pressure P 壳 in the shell side of the shell-and-tube gas mixer is less than the pressure P 管 in the tube side, and P 壳 can be 0.1 - 1 MPa, and P 管 can be greater than 0.1 MPa and not higher than 2 MPa.

[0054] In the present invention, in a preferred case, the method for preparing ethylene carbonate further includes: separating the gas-liquid of the reaction product of the fixed-bed reactor, and returning the separated gas-phase components to the gas mixing unit and / or the fixed-bed reactor for recycling. The gas-liquid separation process can be implemented in a gas-liquid separation tank. When performing gas-liquid separation, the pressure in the gas-liquid separation tank is preferably 1 atmospheric pressure. More preferably, a demister is provided at the upper 1 / 5 of the gas-liquid separation tank to prevent liquid entrainment of the gas-phase material when the gas velocity is too fast.

[0055] In some specific embodiments, the method for preparing ethylene carbonate includes:

[0056] (1) Mixing ethylene, O 2 and CO 2 in a gas mixing unit to obtain a mixed gas of ethylene, O 2 and CO 2 . Among them, the molar ratio of ethylene, O 2 and CO 2 is 1:(0.8 - 5):(4 - 20);

[0057] (2) passing the mixed gas into a fixed bed reactor to react at 150-260° C., wherein the fixed bed reactor is loaded with a solid catalyst as a catalyst bed, and the solid catalyst includes a carrier and an active component and a halogen-containing compound supported on the carrier, wherein the active component is silver;

[0058] (3) separating the reaction product of the fixed bed reactor into gas and liquid, and returning the separated gas phase component to the gas mixing unit and / or the fixed bed reactor for recycling.

[0059] In other specific embodiments, the method for preparing ethylene carbonate comprises:

[0060] (1) Ethylene, O 2 and CO 2 Mix in the gas mixing unit to obtain ethylene, O 2 and CO 2 A mixed gas of ethylene, O 2 and CO 2 The molar ratio is 1:(0.9-2):(4-10);

[0061] (2) The mixed gas is introduced into a fixed bed reactor for reaction at 180-230° C. The outlet pressure of the fixed bed reactor is 0.1-1 MPa, and the raw material space velocity is 2000-12000 mL / (g cat h), wherein the fixed bed reaction is loaded with a solid catalyst as a catalyst bed, wherein the solid catalyst comprises a carrier and an active component and a halogen-containing compound supported on the carrier, wherein the active component is silver, and the halogen-containing compound is butylammonium bromide, propylammonium bromide, ZnBr 2 , at least one of KBr and KI;

[0062] (3) separating the reaction product of the fixed bed reactor into gas and liquid, and returning the separated gas phase component to the gas mixing unit and / or the fixed bed reactor for recycling.

[0063] like Figure 1 As shown, the system for preparing ethylene carbonate of the present invention comprises:

[0064] The raw gas supply unit is used to supply ethylene, O 2 and CO 2 ;

[0065] The gas mixing unit 1 is used to mix the ethylene and O from the raw gas supply unit. 2 and CO 2 Mixing is performed;

[0066] A fixed bed reactor 2, filled with a solid catalyst, through which the mixed gas from the gas mixing unit is reacted, wherein the solid catalyst comprises a carrier and an active component and a halogen-containing compound supported on the carrier, wherein the active component is silver;

[0067] A gas-liquid separation unit 3, used for performing gas-liquid separation on the reaction product of the fixed bed reactor;

[0068] The raw gas circulation unit 4 is used to return the gas phase components separated in the gas-liquid separation unit to the gas mixing unit and / or the fixed bed reactor for recycling.

[0069] In the system described in the present invention, the gas mixing unit 1 can be a static gas mixer or a tube-in-tube gas mixer. When the gas mixing unit 1 is a static gas mixer, Figure 1 As shown, the gas mixing unit 1 is composed of two groups of static gas mixers. First, carbon dioxide and oxygen are mixed in the first static gas mixer to form a mixed gas of carbon dioxide and oxygen. Then, the mixed gas is mixed with ethylene in the second static gas mixer to achieve uniform mixing of ethylene, oxygen and carbon dioxide. When the gas mixing unit 1 is a tube-in-tube gas mixer, the tubes of the tube-in-tube gas mixer are oxygen permeable membrane tubes, such as Figure 2 As shown, ethylene and carbon dioxide are mixed through the pipeline and enter the shell side, and oxygen (for example, provided by air) enters the tube side. There is a positive pressure drop between the tube side and the shell side. Due to the pressure drop, oxygen passes through the membrane tube and enters the shell side to achieve mixing with ethylene and carbon dioxide. The oxygen permeation rate is adjusted by the pressure drop.

[0070] In the system described in the present invention, the fixed bed reactor 2 is a downward fixed bed reactor. The gas mixing unit 1 is connected to the fixed bed reactor 2 through a pipeline, and the mixed gas from the gas mixing unit 1 enters the downward fixed bed reactor by self-pressure, and passes through the catalyst bed in the fixed bed reactor from top to bottom. Preferably, a one-way valve is provided on the connecting pipeline between the gas mixing unit 1 and the fixed bed reactor 2 to prevent the material in the fixed bed reactor from being reversed.

[0071] In the system described in the present invention, the gas-liquid separation unit 3 can be a gas-liquid separation tank. The top and bottom of the gas-liquid separation tank are respectively provided with a discharge port, and the gas phase material is produced from the top discharge port, and the liquid phase material is produced from the bottom discharge port. Preferably, a defoamer is provided at the upper 1 / 5 of the gas-liquid separation tank to prevent the gas phase material from carrying liquid when the gas velocity is too fast.

[0072] In the system described in the present invention, the raw gas circulation unit 4 can be a high-pressure pump, which is used to inject the gaseous material extracted from the top outlet of the gas-liquid separation tank into the gas mixing unit and / or the fixed bed reactor to achieve the recycling of unreacted materials.

[0073] In the present invention, preferably, each device in the system is made of 316L stainless steel.

[0074] In some specific embodiments, the method for preparing ethylene carbonate described above is implemented in the above system. Specifically, the method comprises:

[0075] Ethylene, O 2 and CO 2 The raw material is respectively transported to the gas mixing unit 1 through the raw material supply unit for mixing to obtain ethylene, O 2 and CO 2 A mixed gas of ethylene, O 2 and CO 2 The molar ratio is 1:(0.8-5):(4-20);

[0076] The mixed gas from the gas mixing unit 1 is introduced into the fixed bed reactor 2 to react at 150-260° C., wherein the fixed bed reactor is filled with a solid catalyst as a catalyst bed, and the solid catalyst includes a carrier and an active component and a halogen-containing compound loaded on the carrier, wherein the active component is silver, and the halogen-containing compound is butylammonium bromide, propylammonium bromide, ZnBr 2 , at least one of KBr and KI;

[0077] The reaction product of the fixed bed reactor 2 is transported to the gas-liquid separation unit 3 for gas-liquid separation, and a crude ethylene carbonate product (i.e., a crude EC product) is obtained from the separated liquid phase;

[0078] The gas phase components separated from the gas-liquid separation unit 3 are returned to the gas mixing unit and / or the fixed bed reactor through the raw gas circulation unit 4 for recycling.

[0079] The following examples further illustrate the method and system for preparing ethylene carbonate of the present invention. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

[0080] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0081] Example 1

[0082] (1) Preparation of solid catalyst

[0083] Weigh 0.5g of silver nitrate and dissolve it in 10mL of water for later use, weigh 5g of magnesium aluminum hydrotalcite and place it in a 20mL brown glass bottle, use a pipette to take 5mL of silver nitrate aqueous solution and disperse it on the magnesium aluminum hydrotalcite in the brown bottle, cover the bottle cap, and stand it at room temperature in the dark for 12h, then place it in a 70℃ oven to dry. The obtained sample was reduced in a hydrogen-nitrogen mixed gas (hydrogen content is 10 volume %) at 300℃ for 5h to obtain a catalyst intermediate.

[0084] 2.0 g of the catalyst intermediate was weighed and placed in 300 mL of 0.8 mol / L potassium bromide aqueous solution and stirred for 4 h. The mixture was filtered and washed three times, and then dried at 70 ° C for 12 h to obtain a solid catalyst Cat-1, wherein the inductively coupled plasma emission spectrometer and ion chromatography tests showed that the silver content was 2.7 parts by weight relative to 100 parts by weight of magnesium aluminum hydrotalcite, and the content of potassium bromide in terms of bromine element was 2.1 parts by weight.

[0085] (2) Synthesis of Ethylene Carbonate

[0086] This embodiment Figure 1 The system shown is implemented, specifically, CO 2 and O 2 Mixing is achieved in a first static gas mixer according to a ratio to form a mixed gas; then the mixed gas and ethylene are mixed in a second static gas mixer according to a ratio to obtain a mixed raw gas, wherein ethylene / O 2 / CO 2 The molar ratio is 1 / 1 / 8, and the pressure of the gas mixing unit is 0.2MPa. The mixed raw material gas is pressed into the descending fixed bed reactor filled with solid catalyst Cat-1 by self-pressure. The outlet pressure of the fixed bed reactor is 0.1MPa, and the raw material space velocity is 8000mL / (g cat h), reaction temperature 200°C; the reaction products come out of the downward fixed bed reactor and enter the gas-liquid separation tank for separation, and the gas phase components (unreacted ethylene, O 2 and CO 2 ) are sampled and analyzed, and the rest are pumped into the gas mixing unit for recycling. The liquid component (crude ethylene carbonate) is taken from the bottom of the gas-liquid separation tank for analysis.

[0087] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 12.1% and the selectivity of ethylene carbonate was 92.2%.

[0088] Example 2

[0089] (1) Preparation of solid catalyst

[0090] A solid catalyst was prepared according to the method of Example 1, except that the amount of raw materials was adjusted so that in the prepared solid catalyst Cat-2, the silver content was 3.1 parts by weight relative to 100 parts by weight of magnesium aluminum hydrotalcite, and the potassium bromide content in terms of bromine element was 1.3 parts by weight.

[0091] (2) Synthesis of Ethylene Carbonate

[0092] This embodiment Figure 1 The system shown is implemented, specifically, CO 2 and O 2 Mixing is achieved in a first static gas mixer according to a ratio to form a mixed gas; then the mixed gas and ethylene are mixed in a second static gas mixer according to a ratio to obtain a mixed raw gas, wherein ethylene / O 2 / CO 2 The molar ratio is 1 / 1 / 7, and the pressure of the gas mixing unit is 0.4 MPa. The mixed raw material gas is pressed into the descending fixed bed reactor filled with solid catalyst Cat-2 by self-pressure. The outlet pressure of the fixed bed reactor is 0.2 MPa, and the raw material space velocity is 6000 mL / (g cat h), reaction temperature 180°C; the reaction products come out of the downward fixed bed reactor and enter the gas-liquid separation tank for separation, and the gas phase components (unreacted ethylene, O 2 and CO 2 ) are sampled and analyzed, and the rest are pumped into the gas mixing unit for recycling. The liquid component (crude ethylene carbonate) is taken from the bottom of the gas-liquid separation tank for analysis.

[0093] Quantitative analysis and calculation by gas chromatography (with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 11.2% and the selectivity of ethylene carbonate was 91.3%.

[0094] Example 3

[0095] (1) Preparation of solid catalyst

[0096] A solid catalyst was prepared according to the method of Example 1, except that the amount of raw materials was adjusted so that in the prepared solid catalyst Cat-3, the silver content was 1.7 parts by weight relative to 100 parts by weight of magnesium aluminum hydrotalcite, and the potassium bromide content in terms of bromine element was 2.6 parts by weight.

[0097] (2) Synthesis of Ethylene Carbonate

[0098] This embodiment Figure 1 The system shown is implemented, specifically, CO 2 and O 2Mixing is achieved in a first static gas mixer according to a ratio to form a mixed gas; then the mixed gas and ethylene are mixed in a second static gas mixer according to a ratio to obtain a mixed raw gas, wherein ethylene / O 2 / CO 2 The molar ratio is 1 / 1 / 6, and the pressure of the gas mixing unit is 0.5MPa; the mixed raw material gas is pressed into the descending fixed bed reactor filled with solid catalyst Cat-3 by self-pressure, the outlet pressure of the fixed bed reactor is 0.3MPa, and the raw material space velocity is 7000mL / (g cat h), reaction temperature 230°C; the reaction products come out of the downward fixed bed reactor and enter the gas-liquid separation tank for separation, and the gas phase components (unreacted ethylene, O 2 and CO 2 ) are sampled and analyzed, and the rest are pumped into the gas mixing unit for recycling. The liquid component (crude ethylene carbonate) is taken from the bottom of the gas-liquid separation tank for analysis.

[0099] Quantitative analysis and calculation by gas chromatography (with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 10.1% and the selectivity of ethylene carbonate was 92.4%.

[0100] Example 4

[0101] (1) Preparation of solid catalyst

[0102] A solid catalyst was prepared according to the method of Example 1, except that potassium iodide aqueous solution was used instead of potassium bromide aqueous solution to prepare solid catalyst Cat-4, wherein the silver content was 2.1 parts by weight relative to 100 parts by weight of magnesium aluminum hydrotalcite, and the potassium iodide content in terms of iodine element was 2.2 parts by weight.

[0103] (2) Synthesis of Ethylene Carbonate

[0104] This embodiment Figure 1 The system shown is implemented, specifically, CO 2 and O 2 Mixing is achieved in a first static gas mixer according to a ratio to form a mixed gas; then the mixed gas and ethylene are mixed in a second static gas mixer according to a ratio to obtain a mixed raw gas, wherein ethylene / O 2 / CO 2 The molar ratio is 1 / 1 / 5, and the pressure of the gas mixing unit is 0.8MPa; the mixed raw material gas is pressed into the descending fixed bed reactor filled with solid catalyst Cat-4 by self-pressure, the outlet pressure of the fixed bed reactor is 0.5MPa, and the raw material space velocity is 10000mL / (g cat h), reaction temperature 210°C; the reaction products come out of the downward fixed bed reactor and enter the gas-liquid separation tank for separation, and the gas phase components (unreacted ethylene, O 2and CO 2 ) are sampled and analyzed, and the rest are pumped into the gas mixing unit for recycling. The liquid component (crude ethylene carbonate) is taken from the bottom of the gas-liquid separation tank for analysis.

[0105] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 9.7% and the selectivity of ethylene carbonate was 91.1%.

[0106] Example 5

[0107] (1) Preparation of solid catalyst

[0108] The solid catalyst Cat-1 was prepared according to the method of Example 1.

[0109] (2) Synthesis of Ethylene Carbonate

[0110] This embodiment Figure 1 The system shown is implemented, specifically, CO 2 and O 2 Mixing is achieved in a first static gas mixer according to a ratio to form a mixed gas; then the mixed gas and ethylene are mixed in a second static gas mixer according to a ratio to obtain a mixed raw gas, wherein ethylene / O 2 / CO 2 The molar ratio is 1 / 1 / 8, and the pressure of the gas mixing unit is 0.3MPa. The mixed raw material gas is pressed into the descending fixed bed reactor filled with solid catalyst Cat-1 by self-pressure. The outlet pressure of the fixed bed reactor is 0.2MPa, and the raw material space velocity is 4000mL / (g cat h), reaction temperature 190°C; the reaction products come out of the downward fixed bed reactor and enter the gas-liquid separation tank for separation, and the gas phase components (unreacted ethylene, O 2 and CO 2 ) are sampled and analyzed, and the rest are pumped into the gas mixing unit for recycling. The liquid component (crude ethylene carbonate) is taken from the bottom of the gas-liquid separation tank for analysis.

[0111] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 13.7% and the selectivity of ethylene carbonate was 91.5%.

[0112] Example 6

[0113] (1) Preparation of solid catalyst

[0114] The solid catalyst Cat-1 was prepared according to the method of Example 1.

[0115] (2) Synthesis of Ethylene Carbonate

[0116] This embodiment Figure 1The system shown is implemented, specifically, CO 2 and O 2 Mixing is achieved in a first static gas mixer according to a ratio to form a mixed gas; then the mixed gas and ethylene are mixed in a second static gas mixer according to a ratio to obtain a mixed raw gas, wherein ethylene / O 2 / CO 2 The molar ratio is 1 / 1 / 10, and the pressure of the gas mixing unit is 0.2MPa; the mixed raw material gas is pressed into the descending fixed bed reactor filled with solid catalyst Cat-1 by self-pressure, the outlet pressure of the fixed bed reactor is 0.1MPa, and the raw material space velocity is 12000mL / (g cat h), reaction temperature 220°C; the reaction products come out of the downward fixed bed reactor and enter the gas-liquid separation tank for separation, and the gas phase components (unreacted ethylene, O 2 and CO 2 ) are sampled and analyzed, and the rest are pumped into the gas mixing unit for recycling. The liquid component (crude ethylene carbonate) is taken from the bottom of the gas-liquid separation tank for analysis.

[0117] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 10.4% and the selectivity of ethylene carbonate was 91.8%.

[0118] Example 7

[0119] (1) Preparation of solid catalyst

[0120] A solid catalyst was prepared according to the method of Example 1, except that zinc-magnesium-aluminum hydrotalcite was used instead of magnesium-aluminum hydrotalcite, to prepare a solid catalyst Cat-7.

[0121] (2) Synthesis of Ethylene Carbonate

[0122] Ethylene carbonate was synthesized according to the method of Example 1, except that the solid catalyst Cat-7 was loaded in the descending fixed bed reactor.

[0123] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 11.9% and the selectivity of ethylene carbonate was 93.3%.

[0124] Comparative Example 1

[0125] Ethylene carbonate was synthesized according to the method of Example 1, except that the same molar amount of N 2 Replacement of CO 2 .

[0126] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 12.3% and the selectivity of ethylene carbonate was 0%.

[0127] Comparative Example 2

[0128] The solid catalyst was prepared and ethylene carbonate was synthesized according to the method of Example 1, except that the catalyst intermediate prepared in Example 1 was directly used as the solid catalyst D1 (that is, the solid catalyst was not loaded with a halogen-containing compound); and in the process of synthesizing ethylene carbonate, the solid catalyst loaded in the fixed bed reactor was the solid catalyst D1.

[0129] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 11.7% and the selectivity of ethylene carbonate was 16.3%.

[0130] Comparative Example 3

[0131] Ethylene carbonate was synthesized according to the method of Example 1, except that ethylene, O 2 and CO 2 Input according to the molar ratio of 1 / 1 / 3.

[0132] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that a slight deflagration occurred in the fixed bed reactor.

[0133] Comparative Example 4

[0134] Ethylene carbonate was synthesized according to the method of Example 1, except that O 2 .

[0135] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 0% and the selectivity of ethylene carbonate was 0%.

[0136] Comparative Example 5

[0137] The solid catalyst was prepared and ethylene carbonate was synthesized according to the method of Example 1, except that, in the process of preparing the solid catalyst, silver nitrate was not added to obtain solid catalyst D2 (i.e., the solid catalyst was not loaded with silver); and, in the process of synthesizing ethylene carbonate, the solid catalyst loaded in the fixed bed reactor was solid catalyst D2.

[0138] Quantitative analysis and calculation by gas chromatography (equipped with HP-1 chromatographic column) revealed that the single-pass conversion of ethylene was 0% and the selectivity of ethylene carbonate was 0%.

[0139] It can be seen from the results of the above examples and comparative examples that the method according to the present invention achieves the use of a continuous synthesis process for the synthesis of ethylene, O 2 With CO 2 Ethylene carbonate is synthesized in one step in the same fixed bed reactor with high selectivity for ethylene carbonate.

[0140] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing ethylene carbonate, It is characterized in that The method comprises: in the presence of a solid catalyst, reacting ethylene, O 2 and CO 2 Reaction, wherein ethylene, O 2 and CO 2 The molar ratio of is 1:(0.8-5):(4-20), the solid catalyst comprises a carrier and an active component and a halogen-containing compound loaded on the carrier, wherein the active component is silver.

2. The method according to claim 1, It is characterized in that In the solid catalyst, relative to 100 parts by weight of the carrier, the content of the active component is 0.1-5 parts by weight, preferably 1-4 parts by weight; the content of the halogen-containing compound in terms of halogen element is 0.1-5 parts by weight, preferably 1-3 parts by weight.

3. The method according to claim 1 or 2, It is characterized in that The carrier is a catalyst carrier capable of providing acid and base active sites; Preferably, the carrier is selected from at least one of a molecular sieve and a metal oxide; Preferably, the molecular sieve is TS-1 titanium silicalite molecular sieve; Preferably, the metal oxide is aluminum oxide, magnesium oxide, zinc oxide and mixed metal oxides thereof.

4. The method according to claim 1 or 2, It is characterized in that The halogen-containing compound is butylammonium bromide, propylammonium bromide, ZnBr 2 , KBr and KI.

5. The method according to any one of claims 1 to 4, It is characterized in that The reaction temperature is 150-260°C.

6. The method according to any one of claims 1 to 5, It is characterized in that The reaction is carried out in a fixed bed reactor.

7. The method according to claim 6, It is characterized in that The outlet pressure of the fixed bed reactor is 0.1-1 MPa, and the raw material space velocity is 2000-12000 mL / (g cat h).

8. The method according to claim 6 or 7, It is characterized in that Ethylene, O 2 and CO 2 After being mixed in the gas mixing unit, the gases enter the fixed bed reactor for reaction.

9. The method according to claim 8, It is characterized in that The method further comprises: performing gas-liquid separation on the reaction product of the fixed bed reactor, and returning the separated gas phase component to the gas mixing unit and / or the fixed bed reactor for recycling.

10. A system for preparing ethylene carbonate, It is characterized in that The system includes: The raw gas supply unit is used to supply ethylene, O 2 and CO 2 ; A gas mixing unit for mixing ethylene, O 2 and CO 2 Mixing is performed; A fixed bed reactor filled with a solid catalyst, through which the mixed gas from the gas mixing unit is reacted, wherein the solid catalyst comprises a carrier and an active component and a halogen-containing compound supported on the carrier; A gas-liquid separation unit, used for performing gas-liquid separation on the reaction product of the fixed bed reactor; The raw gas circulation unit is used to return the gas phase components separated in the gas-liquid separation unit to the gas mixing unit and / or the fixed bed reactor for recycling.

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