Method and system for preparing methyl glycolate through continuous catalytic hydrogenation

Abstract

The invention belongs to the technical field of chemical engineering, and particularly relates to a method and system for preparing methyl glycolate through continuous catalytic hydrogenation. Putting a catalyst into the MG synthesis reactor, and introducing hydrogen into the MG synthesis reactor, so that the catalyst is reduced in the MG synthesis reactor; opening a DMO feeding system, introducing the gasified DMO into the MG synthesis reactor, and reacting to obtain a mixed product; the method comprises the following steps: transferring heat of a mixed product to hydrogen by using a heat exchanger, introducing the hydrogen carrying heat into a DMO vaporizing chamber, introducing the mixed product into a high-pressure separator for gas-liquid separation to form gas-phase hydrogen and a liquid-phase material, introducing the gas-phase hydrogen into a circulating compressor, carrying out heat exchange through the heat exchanger, introducing the gas-phase hydrogen into the DMO vaporizing chamber, and introducing the liquid-phase material into the DMO vaporizing chamber. And the liquid-phase material is introduced into the material receiving tank or the heavy component removal tower, so that the heat utilization efficiency can be improved, and the energy consumption can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and particularly relates to a method and a system for preparing methyl glycolate by continuous catalytic hydrogenation. Background Art

[0002] As an important chemical raw material, methyl glycolate plays a key role in organic synthesis and is the basic material for synthesizing many organic compounds. It is widely used in the fields of chemical industry, medicine, pesticide, feed, fragrance and dye.

[0003] However, the hydrogenation of dimethyl oxalate to produce methyl glycolate is an exothermic reaction. During the catalytic reaction, hydrogen as a reaction gas will carry away a large amount of heat from the catalyst bed. If cooling is performed directly at this time, heat waste will be caused, and steam consumption will be further increased, thereby increasing energy consumption. Therefore, it is necessary to design a method and system for preparing methyl glycolate by continuous catalytic hydrogenation to solve the above problems. Summary of the invention

[0004] In view of the above problems, the present invention provides a method and system for preparing methyl glycolate by continuous catalytic hydrogenation to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing methyl glycolate by continuous catalytic hydrogenation, comprising the following steps: Step S1, placing a catalyst in the MG synthesis reactor, opening a hydrogen inlet system, and introducing hydrogen into the MG synthesis reactor, so that the catalyst is reduced in the MG synthesis reactor; Step S2, opening the DMO feeding system, and sequentially introducing DMO into the DMO buffer tank, the feeding pump, and the DMO gasification chamber, gasifying the DMO in the DMO gasification chamber, and introducing the gasified DMO into the MG synthesis reactor to obtain a mixed product after the reaction; Step S3, using a heat exchanger to transfer the heat of the mixed product to the hydrogen, passing the hydrogen carrying the heat into the DMO vaporization chamber, passing the mixed product into a high-pressure separator for gas-liquid separation to form gas-phase hydrogen and liquid-phase materials, passing the gas-phase hydrogen into a circulation compressor, exchanging heat through a heat exchanger, and then passing the gas-phase hydrogen into the DMO vaporization chamber, and passing the liquid-phase materials into a receiving tank or a deweighting tower.

[0006] Furthermore, the step S1 includes: Step S11, placing a copper-based or silver-based catalyst in a MG synthesis reactor; Step S12, open the hydrogen intake system, adjust the temperature in the MG synthesis reactor to a first preset temperature, reduce the copper or silver catalyst in the MG synthesis reactor for a first preset time, and then adjust the temperature in the MG synthesis reactor to a second preset temperature.

[0007] Furthermore, the step S2 includes: Step S21, opening the DMO feeding system, passing DMO into the DMO buffer tank and the feeding pump in sequence and pressurizing the DMO to a first preset pressure before passing the DMO into the DMO vaporization chamber, where the DMO is vaporized; Step S22, introducing the gasified DMO into the MG synthesis reactor to obtain a mixed product after reaction, wherein the pressure in the MG synthesis reactor is a second preset pressure.

[0008] Furthermore, the first preset pressure is between 1.5 MPa and 10 MPa, and the second preset pressure is between 1.5 MPa and 2.5 MPa.

[0009] Furthermore, the first preset temperature is between 100°C and 350°C, the first preset time is between 1h and 6h, the second preset temperature is between 180°C and 250°C, and the ratio of hydrogen to DMO is between 50 and 150.

[0010] The present invention also provides a system for preparing methyl glycolate by continuous catalytic hydrogenation, comprising a dimethyl oxalate feeding unit, a hydrogen feeding unit, a methyl glycolate synthesis unit, and a methyl glycolate receiving unit, wherein the dimethyl oxalate feeding unit comprises a DMO buffer tank, a feeding pump, and a DMO gasification chamber; the hydrogen feeding unit comprises a circulating compressor and a heat exchanger, the methyl glycolate synthesis unit comprises an MG synthesis reactor, and the methyl glycolate receiving unit comprises a high-pressure separator and a receiving mechanism.

[0011] Furthermore, the material receiving mechanism includes a material receiving tank or the deweighting tower.

[0012] Furthermore, the transparent porous polymer support is configured as a disordered porous structure, the porosity of the transparent porous polymer support is 75%-90%, and the porous radius of the holes is in the range of 10-40 μm. The high-pressure separator comprises a shell, a liquid storage cylinder, an inlet, a liquid discharge port, an exhaust port, an exhaust pipe and an umbrella-shaped inlet, the liquid storage cylinder is provided in the shell, the upper end of the liquid storage cylinder is open, the inlet is provided in the shell, and is used to introduce gaseous hydrogen and liquid materials, the liquid materials enter the liquid storage cylinder from the inlet, the liquid discharge port is provided at the lower end of the shell, and the liquid storage cylinder is used to communicate with the liquid discharge port; The exhaust pipe is configured as a spiral structure, the axial direction of the exhaust pipe is parallel to the axial direction of the shell, the lower end of the exhaust pipe is connected to the umbrella-shaped inlet, the upper end of the exhaust pipe is connected to the exhaust port, and the gaseous hydrogen passes through the inlet, the shell, the umbrella-shaped inlet, the exhaust pipe, and the exhaust port in sequence into the circulation compressor.

[0013] Furthermore, the high-pressure separator also includes a motor, a chassis and a stirring rod. The lower end of the liquid storage barrel is open, the chassis is arranged in the liquid storage barrel, the side wall of the chassis is slidably connected to the inner wall of the liquid storage barrel, the chassis and the liquid storage barrel are coaxially arranged, the motor is connected to the lower end of the shell, the output shaft of the motor is transmission-connected to the middle part of the chassis, and the stirring rod is arranged at the upper end of the chassis.

[0014] Furthermore, the high-pressure separator also includes a connecting plate and a hydraulic cylinder, the connecting plate is connected to the liquid storage barrel, the hydraulic cylinder is transmission-connected to the connecting plate, there is a gap between the outer wall of the liquid storage barrel and the inner wall of the shell, and a first liquid drainage hole is opened on the side wall of the lower side of the liquid storage barrel.

[0015] Technical effects and advantages of the present invention: The mixed product passes through a heat exchanger to preheat the hydrogen, and then the heat reaches dimethyl oxalate for utilization, which can avoid heat waste, improve heat utilization efficiency, and reduce energy consumption.

[0016] The method has the advantages of continuous operation and high heat utilization rate, and can separate and purify methyl glycolate, which is conducive to industrial production.

[0017] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A flow chart of a method for preparing methyl glycolate by continuous catalytic hydrogenation according to an embodiment of the present invention is shown; Figure 2A schematic structural diagram of a system for preparing methyl glycolate by continuous catalytic hydrogenation according to another embodiment of the present invention is shown; Figure 3 A schematic diagram showing the external structure of a high-pressure separator according to an embodiment of the present invention is shown; Figure 4 A schematic diagram showing the internal structure of a high-pressure separator according to an embodiment of the present invention is shown; Figure 5 A schematic structural diagram showing another perspective of the interior of a high-pressure separator according to an embodiment of the present invention; Figure 6 A schematic diagram showing the external structure of a liquid storage cylinder according to an embodiment of the present invention is shown; Figure 7 A schematic diagram of the internal structure of a liquid holding cylinder according to an embodiment of the present invention is shown.

[0020] Figure numerals: 1. DMO buffer tank; 2. feed pump; 3. DMO gasification chamber; 4. circulating compressor; 5. MG synthesis reactor; 6. heat exchanger; 7. high-pressure separator; 71. shell; 711. inlet; 712. drain port; 713. exhaust port; 714. second drain hole; 72. liquid storage cylinder; 721. first drain hole; 722. limiting sleeve; 73. exhaust pipe; 74. umbrella-shaped inlet; 751. motor; 752. chassis; 753. stirring rod; 754. cushion block; 761. connecting plate; 762. hydraulic cylinder; 8. material receiving mechanism. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] like Figure 1 As shown, a method for preparing methyl glycolate by continuous catalytic hydrogenation according to an embodiment of the present invention comprises the following steps: Step S1, placing a catalyst in the MG synthesis reactor 5, opening a hydrogen inlet system, and introducing hydrogen into the MG synthesis reactor 5, so that the catalyst is reduced in the MG synthesis reactor 5; Step S2, opening the DMO feeding system, and sequentially passing DMO into the DMO buffer tank 1, the feeding pump 2, and the DMO gasification chamber 3, wherein the DMO is gasified in the DMO gasification chamber 3, and the gasified DMO is passed into the MG synthesis reactor 5, and a mixed product is obtained after the reaction; Step S3, using the heat exchanger 6 to transfer the heat of the mixed product to the hydrogen, the hydrogen carrying the heat is passed into the DMO vaporization chamber 3, the mixed product is passed into the high-pressure separator 7 for gas-liquid separation to form gas-phase hydrogen and liquid-phase materials, the gas-phase hydrogen is passed into the circulation compressor 4, and then heat is exchanged through the heat exchanger 6, and then the gas-phase hydrogen is passed into the DMO vaporization chamber 3, and the liquid-phase material is passed into the receiving tank or the deweighting tower.

[0023] Specifically, DMO is the abbreviation of dimethyl oxalate. The MG synthesis reactor 5 is a shell-and-tube reactor, and the shell medium is water, through which the heat generated by the reaction is removed. At the same time, the temperature of the reactor shell is further controlled by adjusting the pressure of the water / steam mixture.

[0024] Optionally, the step S1 includes: Step S11, placing a copper-based or silver-based catalyst in the MG synthesis reactor 5; Step S12, open the hydrogen intake system, adjust the temperature in the MG synthesis reactor 5 to a first preset temperature, reduce the copper or silver catalyst in the MG synthesis reactor 5 for a first preset time, and then adjust the temperature in the MG synthesis reactor 5 to a second preset temperature.

[0025] Optionally, step S2 includes: Step S21, opening the DMO feeding system, passing DMO into the DMO buffer tank 1 and the feeding pump 2 in sequence and pressurizing the DMO to a first preset pressure before passing the DMO into the DMO vaporization chamber 3, where the DMO is vaporized; Step S22, introducing the gasified DMO into the MG synthesis reactor 5, obtaining a mixed product after reaction, and the pressure in the MG synthesis reactor 5 is a second preset pressure.

[0026] Optionally, the first preset pressure is between 1.5 MPa and 10 MPa, and the second preset pressure is between 1.5 MPa and 2.5 MPa.

[0027] Optionally, the first preset temperature is between 100°C and 350°C, the first preset time is between 1h and 6h, the second preset temperature is between 180°C and 250°C, and the ratio of hydrogen to DMO is between 50 and 150.

[0028] Specifically, [Example 1]: (1) A reaction copper-based catalyst is placed in the MG synthesis reactor 5. The hydrogen inlet system is turned on, and the catalyst is reduced at 250°C for 4 hours in a pure hydrogen environment, and then the temperature is adjusted to 220°C.

[0029] (2) The DMO feeding system is turned on. DMO passes through the DMO buffer tank 1 and is pressurized to 3 MPa by the feed pump 2 before entering the upper portion of the DMO vaporization chamber 3. After DMO is vaporized, it enters the MG synthesis reactor 5. At this time, the reaction pressure is 1.9 MPa.

[0030] (3) The mixed product obtained after the reaction is heat exchanged through the heat exchanger 6, and the heat is transferred to the reaction gas hydrogen. Then the hydrogen carrying the heat enters the DMO vaporization chamber 3 to assist the gasification of DMO. Then the reacted material enters the high-pressure separator 7 for gas-liquid separation. The gaseous hydrogen is further pressurized by the circulation compressor 4, and then heat is exchanged through the heat exchanger 6 and finally enters the DMO vaporization chamber 3 again for circulation feeding, while the liquid phase material enters the receiving tank. At this time, the conversion rate of dimethyl oxalate is 98.9%, and the selectivity of methyl glycolate is 89.3%.

[0031] [Example 2]: (1) A reactive silver catalyst is placed in the MG synthesis reactor 5. The hydrogen inlet system is turned on, and the catalyst is reduced at 300°C for 3 hours in a pure hydrogen environment, and then the temperature is adjusted to 210°C.

[0032] (2) Open the DMO feeding system. DMO passes through the DMO buffer tank 1 and is pressurized to 4 MPa by the feed pump 2 before entering the upper part of the DMO vaporization chamber 3. After DMO is vaporized, it enters the MG synthesis reactor 5. At this time, the reaction pressure is 2.0 MPa.

[0033] (3) The mixed product obtained after the reaction is heat exchanged through the heat exchanger 6, and the heat is transferred to the reaction gas hydrogen, and then the hydrogen carrying the heat enters the DMO vaporization chamber 3 to assist the gasification of DMO. Then the reacted material enters the high-pressure separator 7 for gas-liquid separation, and the gaseous hydrogen is further pressurized by the circulation compressor 4, and then heat exchanged through the heat exchanger 6 and finally enters the DMO vaporization chamber 3 again for circulation feeding, while the liquid phase material enters the deweighting tower. At this time, the conversion rate of dimethyl oxalate is 98.1%, the selectivity of methyl glycolate is 92.5%, and the content of deweighted methyl glycolate is 98.7wt%.

[0034] [Example 3]: (1) A reactive silver catalyst is placed in the MG synthesis reactor 5. The hydrogen inlet system is turned on, and the catalyst is reduced at 280°C for 3 hours in a pure hydrogen environment, and then the temperature is adjusted to 210°C.

[0035] (2) Open the DMO feeding system. DMO passes through the DMO buffer tank 1 and is pressurized to 4 MPa by the feed pump 2 before entering the upper part of the DMO vaporization chamber 3. After the DMO and methanol materials are vaporized, they enter the MG synthesis reactor 5. At this time, the reaction pressure is 2.0 MPa.

[0036] (3) The mixed product obtained after the reaction is heat exchanged through the heat exchanger 6, and the heat is transferred to the reaction gas hydrogen, and then the hydrogen carrying the heat enters the DMO vaporization chamber 3 to assist the gasification of DMO. Then the reacted material enters the high-pressure separator 7 for gas-liquid separation, and the gaseous hydrogen is further pressurized by the circulation compressor 4, and then heat exchanged through the heat exchanger 6 and finally enters the DMO vaporization chamber 3 again for circulation feeding, while the liquid phase material enters the deweighting tower. At this time, the conversion rate of dimethyl oxalate is 99.4%, the selectivity of methyl glycolate is 90.2%, and the content of deweighted methyl glycolate is 99.2wt%.

[0037] A system for preparing methyl glycolate by continuous catalytic hydrogenation according to another embodiment of the present invention is as follows: Figure 2 As shown, it includes a dimethyl oxalate feeding unit, a hydrogen feeding unit, a methyl glycolate synthesis unit, and a methyl glycolate receiving unit. The dimethyl oxalate feeding unit includes a DMO buffer tank 1, a feed pump 2, and a DMO vaporization chamber 3; the hydrogen feeding unit includes a circulating compressor 4 and a heat exchanger 6, the methyl glycolate synthesis unit includes an MG synthesis reactor 5, and the methyl glycolate receiving unit includes a high-pressure separator 7 and a receiving mechanism 8.

[0038] In this embodiment, the DMO buffer tank 1 is connected to the DMO gasification chamber 3 through the feed pump 2; the DMO gasification chamber 3, the MG synthesis reactor 5, the heat exchanger 6, the high-pressure separator 7 and the material receiving mechanism 8 are connected in sequence; the heat exchanger 6 is connected to the DMO gasification chamber 3; the circulating compressor 4 is connected to the heat exchanger 6 and the high-pressure separator 7 respectively.

[0039] Optionally, the material receiving mechanism 8 includes a material receiving tank or the deweighting tower.

[0040] In this embodiment, when the material receiving mechanism 8 is configured as a material receiving tank, methyl glycolate can be collected. When the material receiving mechanism 8 is configured as a deweighting tower, methyl glycolate can be separated and purified to further improve the purity of methyl glycolate.

[0041] Alternatively, if Figures 3 to 5 As shown, the high-pressure separator 7 includes a shell 71, a liquid cylinder 72, an inlet 711, a liquid discharge port 712, an exhaust port 713, an exhaust pipe 73 and an umbrella-shaped inlet 74. The liquid cylinder 72 is arranged in the shell 71, and the upper end of the liquid cylinder 72 is open. The inlet 711 is arranged in the shell 71 and is used to pass gaseous hydrogen and liquid phase materials. The liquid phase material enters the liquid cylinder 72 through the inlet 711. The liquid discharge port 712 is arranged at the lower end of the shell 71, and the liquid cylinder 72 is used to communicate with the liquid discharge port 712. The exhaust pipe 73 is configured as a spiral structure, the axial direction of the exhaust pipe 73 is parallel to the axial direction of the shell 71, the lower end of the exhaust pipe 73 is connected to the umbrella-shaped inlet 74, and the upper end of the exhaust pipe 73 is connected to the exhaust port 713, and the gaseous hydrogen passes through the inlet 711, the shell 71, the umbrella-shaped inlet 74, the exhaust pipe 73, and the exhaust port 713 in sequence and enters the circulation compressor 4.

[0042] Specifically, when the liquid phase material enters the housing 71, a mist-like liquid phase material may be generated, and the mist-like liquid phase material is easily carried by the gas phase hydrogen into the exhaust port 713 for discharge. Secondly, the umbrella-shaped inlet 74 is configured as a hollow conical structure, and the inner wall and the outer wall of the umbrella-shaped inlet 74 are both configured as arc surfaces.

[0043] In this embodiment, after the gaseous hydrogen and liquid-phase materials enter the housing 71 through the inlet 711, the liquid-phase materials enter the liquid-containing cylinder 72 and are discharged through the liquid discharge port 712; the gaseous hydrogen and the water mist-like liquid-phase materials enter the exhaust pipe 73 through the umbrella-shaped inlet 74, and enter the exhaust port 713 along the spiral exhaust pipe 73. By setting the exhaust pipe 73 as a spiral structure, the movement distance of the gaseous hydrogen and the water mist-like liquid-phase materials can be extended, and the water mist-like liquid-phase materials can be condensed into granular liquid-phase materials in the exhaust pipe 73, and flow back into the liquid-containing cylinder 72 along the inner wall arc surface of the exhaust pipe 73 and the umbrella-shaped inlet 74. In this way, the liquid-phase materials in the gaseous hydrogen can be reduced, and the effect of gas-liquid separation can be improved.

[0044] Alternatively, if Figure 2 , Figure 6 and to Figure 7 As shown, the high-pressure separator 7 also includes a motor 751, a chassis 752 and a stirring rod 753. The lower end of the liquid storage cylinder 72 is open, and the chassis 752 is arranged in the liquid storage cylinder 72. The side wall of the chassis 752 is slidably connected to the inner wall of the liquid storage cylinder 72. The chassis 752 is coaxially arranged with the liquid storage cylinder 72. The motor 751 is connected to the lower end of the shell 71, and the output shaft of the motor 751 is transmission-connected to the middle part of the chassis 752. The stirring rod 753 is arranged at the upper end of the chassis 752.

[0045] Specifically, a cushion block 754 is provided at the lower end of the motor 751 .

[0046] In this embodiment, when the liquid material enters the liquid cylinder 72, the motor 751 is used to drive the chassis 752 to rotate, and the stirring rod 753 is driven to rotate in the liquid cylinder 72, so as to stir the liquid material, so that the gaseous hydrogen dissolved in the liquid material is separated, and the effect of gas-liquid separation is further improved.

[0047] Alternatively, if Figures 5 to 7 As shown, the high-pressure separator 7 also includes a connecting plate 761 and a hydraulic cylinder 762. The connecting plate 761 is connected to the liquid storage cylinder 72. The hydraulic cylinder 762 is transmission-connected to the connecting plate 761. There is a gap between the outer wall of the liquid storage cylinder 72 and the inner wall of the shell 71. A first liquid discharge hole 721 is opened on the side wall of the lower side of the liquid storage cylinder 72.

[0048] Specifically, the outer sleeve of the liquid storage cylinder 72 is provided with a limiting sleeve 722 . The limiting sleeve 722 is arranged in a ring shape, and the outer side wall of the limiting sleeve 722 is in contact with the inner side wall of the shell 71 .

[0049] In this embodiment, when the motor 751 is used to drive the stirring rod 753 to rotate, the hydraulic cylinder 762 is used to push the connecting plate 761 to move upward until the bottom plate 752 is located above the first liquid discharge hole 721, so that the liquid phase material can be fully stirred, which is conducive to further removing the gas phase hydrogen. Secondly, after the stirring is completed, the hydraulic cylinder 762 is used to drive the connecting plate 761 to move downward until the bottom plate 752 is located below the first liquid discharge hole 721, so that the liquid phase material in the liquid cylinder 72 can enter the bottom of the shell 71 through the first liquid discharge hole 721, and the liquid phase material enters the liquid discharge port 712 from the second liquid discharge hole 714 at the bottom of the shell 71 and is discharged.

[0050] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing methyl glycolate by continuous catalytic hydrogenation, characterized in that: The following steps are involved: Step S1, placing a catalyst in the MG synthesis reactor (5), opening a hydrogen inlet system, and introducing hydrogen into the MG synthesis reactor (5), so that the catalyst is reduced in the MG synthesis reactor (5); Step S2, opening the DMO feeding system, and sequentially introducing DMO into the DMO buffer tank (1), the feeding pump (2) and the DMO gasification chamber (3), wherein the DMO is gasified in the DMO gasification chamber (3), and the gasified DMO is introduced into the MG synthesis reactor (5), and a mixed product is obtained after the reaction; Step S3, using a heat exchanger (6) to transfer the heat of the mixed product to the hydrogen, passing the hydrogen carrying the heat into the DMO vaporization chamber (3), passing the mixed product into a high-pressure separator (7) for gas-liquid separation to form gas-phase hydrogen and liquid-phase materials, passing the gas-phase hydrogen into a circulation compressor (4), exchanging heat through the heat exchanger (6), then passing the gas-phase hydrogen into the DMO vaporization chamber (3), and passing the liquid-phase materials into a receiving tank or a deweighting tower.

2. The method for preparing methyl glycolate by continuous catalytic hydrogenation according to claim 1, characterized in that: The step S1 comprises: Step S11, placing a copper-based or silver-based catalyst in the MG synthesis reactor (5); Step S12, opening the hydrogen intake system, adjusting the temperature in the MG synthesis reactor (5) to a first preset temperature, reducing the copper-based or silver-based catalyst in the MG synthesis reactor (5) for a first preset time, and then adjusting the temperature in the MG synthesis reactor (5) to a second preset temperature.

3. The method for preparing methyl glycolate by continuous catalytic hydrogenation according to claim 2, characterized in that: The step S2 comprises: Step S21, opening the DMO feeding system, passing DMO into the DMO buffer tank (1) and the feeding pump (2) in sequence and pressurizing the DMO to a first preset pressure before passing the DMO into the DMO vaporization chamber (3), where the DMO is vaporized in the DMO vaporization chamber (3); Step S22, introducing the gasified DMO into the MG synthesis reactor (5), and obtaining a mixed product after reaction, wherein the pressure inside the MG synthesis reactor (5) is a second preset pressure.

4. The method for preparing methyl glycolate by continuous catalytic hydrogenation according to claim 3, characterized in that: The first preset pressure is between 1.5 MPa and 10 MPa, and the second preset pressure is between 1.5 MPa and 2.5 MPa.

5. The method for preparing methyl glycolate by continuous catalytic hydrogenation according to claim 2, characterized in that: The first preset temperature is between 100°C and 350°C, the first preset time is between 1h and 6h, the second preset temperature is between 180°C and 250°C, and the ratio of hydrogen to DMO is between 50 and 150.

6. A system for preparing methyl glycolate by continuous catalytic hydrogenation, characterized in that: A method for preparing methyl glycolate by continuous catalytic hydrogenation as claimed in any one of claims 1 to 5, comprising a dimethyl oxalate feeding unit, a hydrogen feeding unit, a methyl glycolate synthesis unit and a methyl glycolate receiving unit, wherein the dimethyl oxalate feeding unit comprises a DMO buffer tank (1), a feed pump (2) and a DMO vaporization chamber (3); the hydrogen feeding unit comprises a circulating compressor (4) and a heat exchanger (6); the methyl glycolate synthesis unit comprises an MG synthesis reactor (5); and the methyl glycolate receiving unit comprises a high-pressure separator (7) and a receiving mechanism (8).

7. The system for preparing methyl glycolate by continuous catalytic hydrogenation according to claim 6, characterized in that: The material receiving mechanism (8) comprises a material receiving tank or a deweighting tower.

8. The system for preparing methyl glycolate by continuous catalytic hydrogenation according to claim 6, characterized in that: The high-pressure separator (7) comprises a shell (71), a liquid storage cylinder (72), an inlet (711), a liquid discharge port (712), an exhaust port (713), an exhaust pipe (73) and an umbrella-shaped inlet (74); the liquid storage cylinder (72) is arranged in the shell (71); the upper end of the liquid storage cylinder (72) is open; the inlet (711) is arranged in the shell (71) and is used to introduce gaseous hydrogen and liquid-phase materials; the liquid-phase materials enter the liquid storage cylinder (72) through the inlet (711); the liquid discharge port (712) is arranged at the lower end of the shell (71); and the liquid storage cylinder (72) is used to communicate with the liquid discharge port (712); The lower end of the exhaust pipe (73) is connected to the umbrella-shaped inlet (74), and the upper end of the exhaust pipe (73) is connected to the exhaust port (713). The gaseous hydrogen passes through the inlet (711), the shell (71), the umbrella-shaped inlet (74), the exhaust pipe (73), and the exhaust port (713) in sequence and enters the circulation compressor (4).

9. The system for preparing methyl glycolate by continuous catalytic hydrogenation according to claim 8, characterized in that: The high-pressure separator (7) further comprises a motor (751), a chassis (752) and a stirring rod (753); the lower end of the liquid storage barrel (72) is open; the chassis (752) is arranged in the liquid storage barrel (72); the side wall of the chassis (752) is slidably connected to the inner side wall of the liquid storage barrel (72); the chassis (752) and the liquid storage barrel (72) are coaxially arranged; the motor (751) is connected to the lower end of the housing (71); the output shaft of the motor (751) is transmission-connected to the middle part of the chassis (752); and the stirring rod (753) is arranged at the upper end of the chassis (752).

10. The system for preparing methyl glycolate by continuous catalytic hydrogenation according to claim 9, characterized in that: The high-pressure separator (7) further comprises a connecting plate (761) and a hydraulic cylinder (762), wherein the connecting plate (761) is connected to the liquid storage cylinder (72), and the hydraulic cylinder (762) is drivingly connected to the connecting plate (761), a gap is provided between the outer wall of the liquid storage cylinder (72) and the inner wall of the housing (71), and a first liquid discharge hole (721) is provided on the side wall at the lower side of the liquid storage cylinder (72).

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