Method for continuously producing ethylene glycol from ethylene

Abstract

The invention discloses a method for continuously producing ethylene glycol from ethylene, which comprises the following steps: adding a zinc modified titanium silicalite molecular sieve catalyst and a solvent into a reactor, continuously adding ethylene and a hydrogen peroxide solution into the reactor to carry out gas-solid-liquid three-phase reaction, installing a filter membrane inside the reactor, and after the reaction is carried out, adding a catalyst and a solvent into the reactor, and adjusting the internal and external pressure difference of the reactor, separating the liquid product from the solid catalyst in the reactor through the filter membrane, and discharging the liquid product to obtain the ethylene glycol product. According to the method, the pressure difference inside and outside the reactor is adjusted, the liquid product and the solid catalyst can be separated in the reactor without opening the reaction kettle by installing the special filter membrane in the reactor, and the liquid product separated by the filter membrane can be directly analyzed without further treatment, so that the separation efficiency is improved. And long-period continuous evaluation can be realized.

Description

Technical Field

[0001] The present invention relates to a method for producing ethylene glycol, in particular to a method for continuously producing ethylene glycol from ethylene. Background Art

[0002] The final main product of the ethylene oxidation reaction catalyzed by titanium silicalite is ethylene glycol (EG). Ethylene glycol is an important basic chemical raw material downstream of ethylene. 95% of ethylene glycol is used to produce polyester, and the remaining small part is used to produce fine chemicals such as antifreeze, refrigerants, surfactants, lubricants, plasticizers, etc. There are two types of ethylene glycol production processes: ethylene route and synthesis gas route, and both routes require multiple steps of reaction. The ethylene route is mainly ethylene oxidation under Ag catalysis to produce ethylene oxide (EO), and EO is then hydrated to produce EG. Among them, the EO selectivity of the oxidation process is low (<90%), and at the same time, in order to inhibit the deep oxidation of ethylene and EO, the ethylene single-pass conversion rate is controlled at a low level (<10%), and the energy consumption of ethylene recovery is high; in order to ensure high EG selectivity in the hydration process, the water ratio of the process is high, resulting in a long EG separation process and high energy consumption. The synthesis gas route generally refers to coal-to-synthesis gas, which is then used to prepare ethylene glycol through multiple steps of reactions such as dehydrogenation, oxidation, and hydrogenation. This process technology is not yet mature, and most devices are still unable to operate stably at full load for a long period of time. There are deficiencies such as the EG quality cannot meet the requirements of the polyester industry and the water consumption and energy consumption are high. In addition, domestic and foreign research institutions are also conducting relevant research on coal-to-ethylene glycol and biomass-to-ethylene glycol. Since its synthesis, titanium silicalite has good catalytic activity in the field of catalytic oxidation. Its green catalytic system coupled with hydrogen peroxide has certain advantages over other catalysts in the epoxidation stage: high activity and green and pollution-free. TS-1 titanium silicalite is a catalyst with an MFI topological structure, and the main part of its catalytic activity is the presence of framework titanium in the molecular sieve. Hydrogen peroxide, as an oxygen source, can activate framework titanium under specific solvent conditions to form a five-membered ring active intermediate with a specific structure. The special pore structure of titanium silicalite can selectively adsorb active intermediates; at the same time, after zinc modification, TS-1 titanium silicalite can inhibit the conversion of framework titanium to non-framework titanium in the molecular sieve, which is beneficial to improve the catalytic activity of the catalyst.

[0003] Chinese patent CN201911176887.9 discloses a method for preparing ethylene glycol by ethylene oxidation, in which ethylene, hydrogen peroxide solution, a catalyst containing titanium silicon molecular sieve and an organic solvent are contacted and reacted in a slurry bed reactor under oxidation reaction conditions and in the presence of a surfactant, the obtained mixed slurry is subjected to solid-liquid separation, and the obtained liquid phase is subjected to membrane separation treatment to obtain ethylene glycol; however, the product of this method cannot be separated continuously, which is likely to cause serious side reactions.

[0004] Chinese patent CN200710099853.5 discloses a method for continuously producing propylene oxide, using powdered titanium silicon molecular sieve as catalyst, and continuously injecting reaction materials containing propylene and hydrogen peroxide into the reaction system from the feed port, the titanium silicon molecular sieve and the reaction materials are uniformly mixed to react in a slurry state, and under the action of the internal and external pressure difference, the molecular sieve and the liquid reaction materials are separated into solid and liquid in the separation system, and the molecular sieve continues to circulate in the circulation pipeline composed of the reactor and the separation system, while part of the liquid product flows out of the reaction system to obtain the target product. The method has a hydrogen peroxide conversion rate greater than 95%, and a propylene oxide selectivity greater than 90%; however, the method is only applicable to the process of preparing propylene oxide by oxidizing propylene.

[0005] Chinese patent CN201110386708.1 discloses a method for cyclohexene oxidation. Under oxidation reaction conditions, a liquid feed containing cyclohexene, an aqueous hydrogen peroxide solution and an organic solvent is fed from a feed port of a membrane tube reactor into a tubular reactor, and contacts with a titanium silicon molecular sieve in the tubular reactor. The product after contact is separated into solid and liquid through a membrane structure sealed and connected to the outlet end of the tubular reactor. However, this method is only applicable to solid-liquid two-phase reactions.

[0006] Beijing University of Chemical Technology, "Study on the One-Step Preparation of Ethylene Glycol by Using TS-1 Titanium Silica Molecular Sieve to Catalyze Ethylene to Produce Ethylene Glycol", through the exploration and research on the conditions of the autoclave reaction of ethylene catalyzed by TS-1 molecular sieve to produce ethylene glycol, the optimal reaction conditions were determined. The conditions for the reaction of ethylene catalyzed by the extruded TS-1 molecular sieve were optimized in a fixed bed reactor. However, the catalyst used in the fixed bed reactor is extruded, and the powdered catalyst has better evaluation effect in a continuous reaction device.

[0007] One-pot synthesis of ethylene glycol by oxidative hydration of ethylene with hydrogen peroxide over titanosilicate catalysts X. Lu et al. / Journal of Catalysis 358 (2018) 89-99. discloses that Ti-MWW catalyst has excellent performance in selective catalytic oxidation of ethylene to ethylene glycol under the condition that the solvent is water. However, the catalyst has only been evaluated in a batch reactor.

[0008] Chinese patent CN112851477A discloses a method for preparing ethylene glycol by ethylene oxidation, wherein the method comprises: under oxidation reaction conditions, in the presence of a surfactant, ethylene, an aqueous hydrogen peroxide solution, a catalyst containing a titanium silicon molecular sieve and an organic solvent are contacted and reacted in a slurry bed reactor, the obtained mixed slurry is subjected to solid-liquid separation treatment to obtain a mixed liquid containing ethylene glycol; and the mixed liquid is subjected to membrane separation treatment. However, the separation process of this method requires two steps, firstly, solid-liquid separation, and then separation of the liquid product.

[0009] Chinese patent CN101003012A discloses a method for preparing a novel catalytic membrane reactor: (1) preparing a titanium silicon molecular sieve membrane on a porous ceramic tube carrier, so that the titanium silicon molecular sieve preferentially crystallizes and grows on the surface and pores of the carrier tube; (2) designing a pervaporation catalytic membrane reactor, in which one end of the titanium silicon molecular sieve membrane is connected to a small section of polytetrafluoroethylene rod, and the other end is connected to a vacuum system through a section of glass tube, and the two ends are sealed with a silicone rubber tube and a thermoplastic tube respectively; (3) the outer side of the titanium silicon molecular sieve membrane is in contact with the reaction solution, and the inner side is connected to the vacuum system. However, this method uses a porous ceramic tube as a carrier, and the titanium silicon molecular sieve catalyst grows on the surface and pores of the carrier tube. The prepared catalytic membrane reactor requires the preparation of a membrane reactor before evaluating different catalysts, and the evaluation of the diversity of catalysts is time-consuming. Summary of the invention

[0010] The object of the present invention is to provide a method for continuously producing ethylene glycol from ethylene. The method adjusts the pressure difference between the inside and outside of a reactor, and the liquid product passes through a special filter membrane installed inside the reactor. The liquid product and the solid catalyst can be separated in the reactor without opening the reactor. The liquid product separated by the filter membrane does not need further treatment and can be directly analyzed, and long-term continuous evaluation can be achieved.

[0011] To achieve the above object, the present invention provides a method for continuously producing ethylene glycol from ethylene, the method comprising:

[0012] A zinc-modified titanium silicon molecular sieve catalyst and a solvent are added to a reactor, and ethylene and a hydrogen peroxide solution are continuously added to the reactor to carry out a gas-solid-liquid three-phase reaction. A filter membrane is installed inside the reactor. After the reaction is carried out, the pressure difference between the inside and outside of the reactor is adjusted, and the liquid product passes through the filter membrane, and the liquid product and the solid catalyst in the reactor are separated, and the liquid product is discharged to obtain the product ethylene glycol.

[0013] In the method for continuously producing ethylene glycol from ethylene of the present invention, the filter membrane is installed in the cavity of the reactor or embedded in the inner wall of the reactor.

[0014] In the method for continuously producing ethylene glycol from ethylene of the present invention, the pressure difference between the inside and outside of the reactor is +0.01MPa to +0.5MPa.

[0015] In the method for continuously producing ethylene glycol from ethylene of the present invention, the pore size of the filter membrane is smaller than the average particle size of the zinc-modified titanium silicon molecular sieve catalyst; the material of the filter membrane is selected from at least one of mixed fiber, polypropylene, polyether sulfone, polyvinylidene fluoride, polytetrafluoroethylene, nylon, inorganic material ceramics, and titanium.

[0016] The method for continuously producing ethylene glycol from ethylene of the present invention further comprises: after discharging the liquid product, supplementing ethylene and hydrogen peroxide solution to continue the gas-solid-liquid three-phase reaction.

[0017] The method for continuously producing ethylene glycol from ethylene of the present invention, the zinc-modified titanium silicalite catalyst is selected from at least one of the zinc-modified TS-1, Ti-MWW, Ti-MCM-41 and Ti-MOR topological structures, the preferred zinc-modified titanium silicalite catalyst can effectively participate in the oxidation reaction, preferably the zinc-modified TS-1 titanium silicalite.

[0018] In the method for continuously producing ethylene glycol from ethylene of the present invention, the content of the zinc-modified titanium silicon molecular sieve catalyst is 0.1-2.0wt%, which refers to the ratio of the mass of the zinc-modified titanium silicon molecular sieve catalyst to the total mass of the zinc-modified titanium silicon molecular sieve catalyst, solvent and hydrogen peroxide solution in the reactor.

[0019] In the method for continuously producing ethylene glycol from ethylene of the present invention, the zinc-modified titanium silicon molecular sieve catalyst is in powder or molded state, and the molding method includes at least one of spray drying, extrusion molding and in-situ loading method.

[0020] The method for continuously producing ethylene glycol from ethylene of the present invention comprises the following steps: the reaction temperature is 50-80°C, the ethylene pressure is 0.1-3.5 MPa, and the olefin-oxygen molar ratio is 1:10-4:1.

[0021] In the method for continuously producing ethylene glycol from ethylene of the present invention, the solvent is preferably at least one of water, methanol, ethanol and acetonitrile.

[0022] In the method for continuously producing ethylene glycol from ethylene of the present invention, the reactor is a batch reactor, a continuous reactor or a slurry bed reactor.

[0023] In the method for continuously producing ethylene glycol from ethylene of the present invention, the hydrogen peroxide solution is added into the reactor through a metering pump; a stirring paddle is arranged in the reactor; and the reactor is heated by a water bath circulation so that the temperature inside the reactor reaches the reaction temperature.

[0024] According to the method for continuously producing ethylene glycol from ethylene of the present invention, both the introduction of reaction raw materials and the separation of reaction products can be realized continuously, that is, by adjusting the pressure difference between the inside and outside of the reactor, the liquid product passes through a special filter membrane installed inside the reactor, and the liquid product and the solid catalyst can be separated in the reactor without opening the reactor, and the liquid product is discharged in time, thereby reducing the occurrence of side reactions; the liquid product separated by the filter membrane does not need to be further processed and can be directly analyzed; at the same time, without opening the reactor, ethylene and hydrogen peroxide solution are supplemented to continue the gas-solid-liquid three-phase reaction, thereby realizing long-term continuous evaluation.

[0025] The method of the present invention timely separates the generated main product ethylene glycol, avoids polymerization caused by long-term contact of ethylene glycol with oxidants and catalysts, and can not only improve the conversion rate of raw materials and the selectivity of products, but also can evaluate the long-term operation performance of catalysts. The present invention can be used for batch reactors, continuous reactors, slurry bed reactors, etc. In the continuous reactor, the selectivity of ethylene glycol product prepared by one-step oxidation of ethylene reaches 94.2%, the conversion rate of hydrogen peroxide can reach 97.6%, and the evaluation time of zinc-modified titanium silicon molecular sieve catalyst reaches 24 hours; in the batch reactor, the selectivity of ethylene glycol product prepared by one-step oxidation of ethylene reaches 92.6%, and the conversion rate of hydrogen peroxide reaches 96.8%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of an embodiment of a reactor of the present invention, wherein a filter membrane is installed in the cavity of the reactor.

[0027] Figure 2 It is a schematic diagram of another embodiment of the reactor of the present invention, wherein the filter membrane is embedded in the inner wall of the reactor. DETAILED DESCRIPTION

[0028] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and process are given, but the protection scope of the present invention is not limited to the following embodiments. The experimental methods in the following embodiments without specifying specific conditions are usually carried out under conventional conditions.

[0029] Example 1

[0030] Zinc-modified TS-1 titanium silicon molecular sieve catalyst powder with an average particle size of 0.5 μm and solvent water are added to a continuous reactor, and ethylene and hydrogen peroxide solution are continuously added to the reactor for gas-solid-liquid three-phase reaction. Among them, the reaction temperature is 60 ° C, the ethylene pressure is 1.0 MPa, hydrogen peroxide is added to the reactor by continuous pumping, the mass concentration is 4.0wt%, the content of zinc-modified TS-1 titanium silicon molecular sieve catalyst is 1.0wt% mass concentration, and the stirring rate is 1250rpm. The total reaction time is 24h. The filter membrane is installed in the cavity of the reactor, made of titanium, and has a pore size of 0.35μm. After the reaction has been carried out for a certain period of time, there is no need to open the reactor. By adjusting the pressure difference between the inside and outside of the reactor to +0.02MPa, the liquid product is discharged in time through the filter membrane; at the same time, the ethylene pressure is supplemented to 1.0MPa, and the hydrogen peroxide raw material is continued to be added through the metering pump to continue the reaction. Sampling was performed once at 1 h, 4 h, and 24 h of reaction. The reactor was not opened during the sampling process, and the liquid product separated by the filter membrane was directly analyzed by chromatography and titration.

[0031] Example 2

[0032] The filter membrane is embedded in the inner wall of the reactor, and the rest is the same as in Example 1.

[0033] Comparative Example 1

[0034] The difference from Example 1 is that no filter membrane is installed inside the reactor. Others are the same as Example 1.

[0035] Comparative Example 2

[0036] The difference from Example 1 is that "by adjusting the pressure difference between the inside and outside of the reactor to +0.02 MPa" is replaced by "the pressure difference between the inside and outside of the reactor is not adjusted, that is, the pressure difference between the inside and outside of the reactor is 0 MPa". The rest is the same as Example 1.

[0037] Example 3

[0038] An extruded zinc-modified TS-1 titanium silicalite catalyst and solvent water were added to a continuous reactor. The filter membrane material selected was titanium material with a pore size of 100 μm. When sampling, the pressure difference between the inside and outside of the reactor was adjusted to +0.01 MPa. Others were the same as in Example 1.

[0039] Example 4

[0040] An extruded zinc-modified TS-1 titanium silicalite catalyst and solvent water were added to a continuous reactor. The filter membrane material selected was polytetrafluoroethylene, and the pore size of the filter membrane was 100 μm. When sampling, the pressure difference between the inside and outside of the reactor was adjusted to +0.01 MPa. Others were the same as in Example 1.

[0041] Example 5

[0042] Zinc-modified Ti-MWW titanium silicon molecular sieve catalyst powder with an average particle size of 1.0 μm and solvent water were added to a continuous reactor, the catalyst addition amount was 0.1 wt%, the ethylene pressure was 2.5 MPa, and the reaction temperature was 50° C. The selected filter membrane material was nylon material, the filter membrane pore size was 0.5 μm, and the rest was the same as in Example 1.

[0043] Example 6

[0044] Zinc-modified TS-1 titanium silicon molecular sieve catalyst powder with an average particle size of 0.5 μm and solvent acetonitrile are added to a continuous reactor, and the selected filter membrane is made of titanium with a pore size of 0.35 μm. After the reaction is carried out for a certain period of time, there is no need to open the reactor. By adjusting the pressure difference between the inside and outside of the reactor to +0.01 MPa, the liquid product is discharged in time through the filter membrane; at the same time, the ethylene pressure is supplemented to 1.0 MPa, and the hydrogen peroxide raw material is continued to be added through the metering pump to continue the reaction. Others are the same as Example 1.

[0045] Example 7

[0046] The zinc-modified TS-1 titanium silicon molecular sieve catalyst powder with an average particle size of 0.5 μm and solvent water are added to the continuous reactor, and the selected filter membrane is made of titanium with a pore size of 0.35 μm. Others are the same as Example 1. After the reaction is carried out for a certain period of time, there is no need to open the reactor. By adjusting the pressure difference between the inside and outside of the reactor to +0.5 MPa, the liquid product is discharged in time through the filter membrane; at the same time, the ethylene pressure is supplemented to 1.0 MPa, and the hydrogen peroxide raw material is continued to be added through the metering pump to continue the reaction. Others are the same as Example 1.

[0047] Example 8

[0048] Zinc-modified Ti-MCM-41 titanium silicon molecular sieve catalyst powder with an average particle size of 1.0 μm and solvent water were added to a continuous reactor, the catalyst addition amount was 0.5 wt%, the ethylene pressure was 1.0 MPa, and the reaction temperature was 80° C. The selected filter membrane material was titanium material, the filter membrane pore size was 0.5 μm, and the rest was the same as in Example 1.

[0049] Example 9

[0050] Zinc-modified Ti-MOR titanium silicon molecular sieve catalyst powder with an average particle size of 1.0 μm and solvent ethanol were added to a continuous reactor, the solvent was methanol, the catalyst addition amount was 0.2 wt%, the ethylene pressure was 1.5 MPa, and the reaction temperature was 60° C. The selected filter membrane material was titanium material, the filter membrane pore size was 0.5 μm, and the rest was the same as in Example 1.

[0051] Example 10

[0052] Zinc-modified Ti-MWW titanium silicon molecular sieve catalyst powder with an average particle size of 1.0 μm and solvent water were added to a continuous reactor, the catalyst addition amount was 4.0 wt%, the ethylene pressure was 3.5 MPa, and the reaction temperature was 50° C. The selected filter membrane material was nylon material, the filter membrane pore size was 0.5 μm, and the rest was the same as in Example 1.

[0053] Embodiment 11

[0054] Zinc-modified TS-1, zinc-modified Ti-MWW, zinc-modified Ti-MCM-41 and zinc-modified Ti-MOR titanium silicon molecular sieve catalyst powders with an average particle size of 1.0 μm were selected and mixed with solvent water in a ratio of 1:1:1:1 and added to a continuous reactor. The total catalyst proportion was 2.0 wt%. The selected filter membrane material was titanium material, the filter membrane pore size was 0.5 μm, and the pressure difference between the inside and outside of the reactor was adjusted to +0.02 MPa during sampling. The rest was the same as Example 1.

[0055] Table 1

[0056]

[0057]

[0058] From the results of Example 1 and Comparative Example 1, it can be seen that when the filter membrane is not installed inside the reactor, the selectivity of ethylene glycol and the conversion rate of H2O2 are low, and when the filter membrane is installed inside the reactor, the selectivity of ethylene glycol and the conversion rate of H2O2 are greatly improved. From the results of Example 1 and Comparative Example 2, it can be seen that when the pressure difference between the inside and outside of the reactor is not adjusted, the selectivity of ethylene glycol and the conversion rate of H2O2 are low, and after adjusting the pressure difference between the inside and outside of the reactor, the selectivity of ethylene glycol and the conversion rate of H2O2 are greatly improved.

[0059] Example 12

[0060] The zinc-modified TS-1 titanium silicon molecular sieve catalyst powder with an average particle size of 0.5 μm and solvent water are added to the batch reactor, and ethylene and hydrogen peroxide solution are continuously added to the reactor for gas-solid-liquid three-phase reaction. Among them, the reaction temperature is 60 ° C, the ethylene pressure is 2.0 MPa, hydrogen peroxide is added to the reactor by continuous pumping, the mass concentration is 4.0wt%, the zinc-modified TS-1 titanium silicon molecular sieve catalyst content is 1.0wt% mass concentration, and the stirring rate is 1250rpm. The total reaction time is 2h. The filter membrane is installed in the cavity of the batch reactor, made of titanium, and has a pore size of 0.35μm. After the reaction is completed, the pressure difference between the inside and outside of the reactor is adjusted to +0.05MPa, and the product is sampled after passing through the filter membrane. The liquid product separated by the filter membrane is directly analyzed by chromatography and titration.

[0061] Example 13

[0062] The filter membrane is embedded in the inner wall of the reactor, and the rest is the same as Example 12.

[0063] Comparative Example 3

[0064] The difference from Example 12 is that no filter membrane is installed inside the reactor. Others are the same as Example 12.

[0065] Comparative Example 4

[0066] The difference from Example 12 is that "by adjusting the pressure difference between the inside and outside of the reactor to +0.05 MPa" is replaced by "the pressure difference between the inside and outside of the reactor is not adjusted, that is, the pressure difference between the inside and outside of the reactor is 0 MPa". The rest is the same as Example 12.

[0067] Embodiment 14

[0068] An extruded zinc-modified TS-1 titanium silicalite catalyst and solvent water were added to a batch reactor. The filter membrane material selected was titanium material with a pore size of 100 μm. When sampling, the pressure difference between the inside and outside of the reactor was adjusted to +0.01 MPa. The rest was the same as Example 12.

[0069] Embodiment 15

[0070] Zinc-modified Ti-MWW titanium silicon molecular sieve catalyst powder with an average particle size of 1.0 μm and solvent water were added to a batch reactor, the catalyst addition amount was 0.1 wt%, the ethylene pressure was 2.5 MPa, and the reaction temperature was 50° C. The selected filter membrane material was nylon material, the filter membrane pore size was 0.5 μm, and the rest was the same as Example 12.

[0071] Example 16

[0072] Zinc-modified Ti-MCM-41 titanium silicon molecular sieve catalyst powder with an average particle size of 1.0 μm and solvent water were added to a batch reactor, the catalyst addition amount was 0.5 wt%, the ethylene pressure was 1.0 MPa, and the reaction temperature was 80° C. The selected filter membrane material was titanium material, the filter membrane pore size was 0.5 μm, and the rest was the same as in Example 12.

[0073] Embodiment 17

[0074] Zinc-modified Ti-MOR titanium silicon molecular sieve catalyst powder with an average particle size of 1.0 μm and solvent ethanol were added to a batch reactor, the solvent was methanol, the catalyst addition amount was 0.2 wt%, the ethylene pressure was 1.5 MPa, and the reaction temperature was 60° C. The selected filter membrane material was titanium material, the filter membrane pore size was 0.5 μm, and the others were the same as in Example 12.

[0075] Embodiment 18

[0076] Zinc-modified TS-1, zinc-modified Ti-MWW, zinc-modified Ti-MCM-41 and zinc-modified Ti-MOR titanium silicon molecular sieve catalyst powders with an average particle size of 1.0 μm were selected and mixed with solvent water in a ratio of 1:1:1:1 and added to an intermittent reactor. The total catalyst proportion was 2.0 wt%. The selected filter membrane material was titanium material, the filter membrane pore size was 0.5 μm, and the pressure difference between the inside and outside of the reactor was adjusted to +0.02 MPa during sampling. Others were the same as Example 12.

[0077] Table 2

[0078]

[0079] From the results of Example 12 and Comparative Example 3, it can be seen that when the filter membrane is not installed inside the reactor, the selectivity of ethylene glycol and the conversion rate of H2O2 are low, and when the filter membrane is installed inside the reactor, the selectivity of ethylene glycol and the conversion rate of H2O2 are greatly improved. From the results of Example 12 and Comparative Example 4, it can be seen that when the pressure difference between the inside and outside of the reactor is not adjusted, the selectivity of ethylene glycol and the conversion rate of H2O2 are low, and after adjusting the pressure difference between the inside and outside of the reactor, the selectivity of ethylene glycol and the conversion rate of H2O2 are greatly improved.

[0080] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the present invention.

Claims

1. A method for continuously producing ethylene glycol from ethylene, characterized in that: include: A zinc-modified titanium silicon molecular sieve catalyst and a solvent are added to a reactor, and ethylene and a hydrogen peroxide solution are continuously added to the reactor to carry out a gas-solid-liquid three-phase reaction. A filter membrane is installed inside the reactor. After the reaction is carried out, the pressure difference between the inside and outside of the reactor is adjusted, and the liquid product passes through the filter membrane, and the liquid product and the solid catalyst in the reactor are separated, and the liquid product is discharged to obtain the product ethylene glycol.

2. The method according to claim 1, characterized in that The filter membrane is installed in the cavity of the reactor or embedded in the inner wall of the reactor.

3. The method according to claim 1, characterized in that The pressure difference between the inside and outside of the reactor is +0.01MPa to +0.5MPa.

4. The method according to claim 1, characterized in that: The pore size of the filter membrane is smaller than the average particle size of the zinc-modified titanium silicon molecular sieve catalyst; the material of the filter membrane is selected from at least one of mixed fiber, polypropylene, polyethersulfone, polyvinylidene fluoride, polytetrafluoroethylene, nylon, inorganic material ceramics, and titanium.

5. The method according to claim 1, characterized in that The method further comprises: after discharging the liquid product, supplementing ethylene and hydrogen peroxide solution to continue the gas-solid-liquid three-phase reaction.

6. The method according to claim 1, characterized in that The zinc-modified titanium silicon molecular sieve catalyst is selected from at least one of zinc-modified TS-1, Ti-MWW, Ti-MCM-41 and Ti-MOR topological structures; the content of the zinc-modified titanium silicon molecular sieve catalyst is 0.1-2.0wt%.

7. The method according to claim 1, characterized in that The zinc-modified titanium silicon molecular sieve catalyst is in a powdered or molded state, and the molding method includes at least one of spray drying, extrusion molding and in-situ loading method.

8. The method according to claim 1, characterized in that The reaction temperature is 50-80°C, the ethylene pressure is 0.1-3.5 MPa, and the olefin-oxygen molar ratio is 1:10-4:

1.

9. The method according to claim 1, characterized in that: The solvent is preferably at least one of water, methanol, ethanol and acetonitrile.

10. The method according to claim 1, characterized in that The reactor is a batch reactor, a continuous reactor or a slurry bed reactor.

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