Method for prolonging service life of carbonylation catalyst

Abstract

The invention discloses a method for prolonging the service life of a carbonylation catalyst. The method comprises the following steps: S1, synthesizing dimethyl ether; s2, carrying out a carbonylation reaction; s3, hydrogenation reaction; s4, rectification separation; and S5, circular reaction. According to the method, outsourced methanol reacts in a dimethyl ether reactor to generate dimethyl ether, dimethyl ether and carbon monoxide are mixed and then react in a carbonylation reactor to produce methyl acetate, methyl acetate and hydrogen are mixed and then enter a hydrogenation reactor to react to produce crude alcohol, the crude alcohol enters a rectification system, a mixture of methanol and methyl acetate is separated out from the tower top, and methanol and methyl acetate are separated out from the tower bottom. A mixture of ethanol, methanol and methyl acetate separated from a tower kettle is pressurized by a pressure pump and then mixed with methyl acetate and hydrogen, the mixture enters a hydrogenation reactor for reaction, methanol and esters produced by a rectification system are directly sent back to a hydrogenation system for continuous reaction and do not participate in synthesis of dimethyl ether any more, the content of ethylene and propylene in dimethyl ether is reduced, and the yield of dimethyl ether is increased. Therefore, the service life of the carbonylation catalyst is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production, in particular to a method for prolonging the service life of a carbonylation catalyst. Background Art

[0002] Carbonylation reaction is a very important type of reaction in organic chemistry and is widely used in the field of chemical production. The carbonylation reaction is inseparable from the catalyst. The catalyst plays a key role in reducing the activation energy of the reaction, increasing the reaction rate and selectivity during the reaction. Due to the high cost of the catalyst, in industrial production, extending its service life is crucial to reducing production costs.

[0003] In the prior art, the service life of the carbonylation catalyst during use is affected by the ethylene and propylene contents in the raw material dimethyl ether. In the dimethyl ether system, crude alcohol produced by the hydrogenation reaction of methyl acetate will be separated into methanol after distillation. When the system fluctuates, the separated methanol will contain ethanol and propanol. When the methanol containing ethanol and propanol enters the dimethyl ether synthesis unit, the produced dimethyl ether will contain ethylene and propylene, resulting in the ethylene and propylene content in the dimethyl ether exceeding the standard, thereby affecting the service life of the carbonylation catalyst. Summary of the invention

[0004] The object of the present invention is to provide a method for extending the service life of a carbonylation catalyst, so as to solve the problem that crude alcohol produced by hydrogenation reaction of methyl acetate mentioned in the above background technology will separate methanol after distillation, and when the system fluctuates, the separated methanol will contain ethanol and propanol, and the produced dimethyl ether will contain ethylene and propylene, which will affect the service life of the carbonylation catalyst.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for extending the service life of a carbonylation catalyst, comprising the following steps: S1. Dimethyl ether synthesis: purchased methanol is transported to the dimethyl ether reactor through a pipeline and reacts to generate dimethyl ether under the action of a specific catalyst; S2, carbonylation reaction: dimethyl ether and carbon monoxide are mixed and sent into a carbonylation reactor, where a carbonylation reaction is carried out under the action of a catalyst to generate methyl acetate; S3, hydrogenation reaction: methyl acetate and hydrogen are mixed and sent into a hydrogenation reactor, and the catalyst loaded inside the hydrogenation reactor causes methyl acetate and hydrogen to undergo a hydrogenation reaction to generate crude alcohol; S4, distillation separation: the crude alcohol is sent to a distillation system, and the components are separated by using the difference in boiling points of the components in the mixture, a mixture of methanol and methyl acetate is separated at the top of the tower, and ethanol is separated at the bottom of the tower; S5. Circulation reaction: The methanol and methyl acetate mixture separated from the distillation system is pressurized by a pressure pump, mixed with fresh methyl acetate and hydrogen, and sent into the hydrogenation reactor for reaction.

[0006] Preferably, in step S1, the specific catalyst is one of γ-alumina and ZSM-5 molecular sieve.

[0007] Preferably, in step S1, the temperature inside the dimethyl ether reactor is set to 250-350°C, and the pressure is set to 0.5-1.5 MPa.

[0008] Preferably, in step S2, the carbonylation reaction comprises the following steps: S21, drawing carbon monoxide from the carbon monoxide storage device, and feeding it into a mixer for mixing with dimethyl ether in a certain molar ratio, wherein the molar ratio of dimethyl ether to carbon monoxide is 1:1.2-1:1.5; S22, the mixed gas is passed through a buffer tank to stabilize the pressure and flow of the gas, and then sent to the carbonylation reactor, and the catalyst solution is continuously added to the carbonylation reactor using a metering pump; S23, dimethyl ether and carbon monoxide undergo carbonylation reaction under the action of a catalyst to generate methyl acetate. The internal temperature of the carbonylation reactor is set to 150-250°C and the pressure is set to 2-8MPa.

[0009] Preferably, in step S3, the internal temperature of the hydrogenation reactor is set to 180-260° C., the pressure is 3-6 MPa, and the molar ratio of the mixture of methyl acetate and hydrogen is 1:4-1:6.

[0010] Preferably, in step S5, the cyclic reaction comprises the following steps: S51, the mixture of methanol and methyl acetate separated from the top of the distillation system is firstly led out through a pipeline, and a flow regulating valve is installed on the pipeline to control the lead-out amount of the mixture of methanol and methyl acetate; S52, the drawn methanol and methyl acetate mixture is sent to a circulating heat exchange device for heat exchange, and the mixture after heat exchange enters a pressure pump to adjust the pressure of the mixture to 3-6MPa; S53, mixing the pressurized methanol and methyl acetate mixture with fresh methyl acetate and hydrogen, and sending the mixture into a hydrogenation reactor to carry out a hydrogenation reaction with a catalyst.

[0011] Preferably, the circulating heat exchange device includes a circulating feeding mechanism, a fixed base is installed at the bottom of the circulating feeding mechanism, the circulating feeding mechanism includes a heat exchange tube, a third return pipe and a fourth feeding pipe are installed inside the heat exchange tube, one end of the third return pipe is fixedly connected to the fourth return pipe, one end of the fourth return pipe passes through the top of the heat exchange tube, the other end of the third return pipe is fixedly connected to the second return pipe, one end of the second return pipe is fixedly connected to the first pump body, one side of the first pump body is fixedly connected to one side of the fixed base, and one end of the second return pipe is fixedly connected to the first return pipe.

[0012] Preferably, one end of the fourth feeding pipe is fixedly connected to the first feeding pipe, one end of the first feeding pipe passes through one side of the heat exchange tube, the other end of the fourth feeding pipe is fixedly connected to the third feeding pipe, one end of the third feeding pipe passes through the heat exchange tube and is fixedly connected to the second pump body, one side of the second pump body is fixedly connected to one side of the fixed base, one end of the second pump body is fixedly connected to the second feeding pipe, and one end of the second feeding pipe is installed with a hydrogenation reaction mechanism.

[0013] Preferably, the hydrogenation reaction mechanism includes a refining reactor, the bottom of the refining reactor is fixedly connected to one side of the fixed base, the top of the refining reactor is fixedly connected to a driving motor, the output end of the driving motor is fixedly connected to a rotating rod through the top of the refining reactor, the outside of the rotating rod is fixedly connected to a mixing blade, the inner side of the refining reactor is fixedly connected to a catalyst packing rack, the bottom end of the refining reactor is fixedly connected to one end of the second feeding pipe, one end of the first return pipe is fixedly connected to a connecting pipe, and one end of the connecting pipe passes through one side of the refining reactor and is fixedly connected to an annular pipe.

[0014] Preferably, the other end of the fourth return pipe is fixedly connected to a distillation tower, the bottom of the distillation tower is fixedly connected to one side of the fixed base, and the outer side of the distillation tower is fixedly connected to the other end of the first feed pipe.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, purchased methanol is passed through a pipeline to a dimethyl ether reactor to produce dimethyl ether, mixed with carbon monoxide and then reacted in a carbonylation reactor to produce methyl acetate, methyl acetate is mixed with hydrogen and then enters a hydrogenation reactor to react and produce crude alcohol, the crude alcohol enters a distillation system, a mixture of methanol and methyl acetate is separated at the top of the tower, ethanol is separated at the bottom of the tower, the mixture of methanol and methyl acetate is pressurized by a pressure pump, mixed with methyl acetate and hydrogen and then enters a hydrogenation reactor for reaction, so that methanol only circulates in the system and no longer participates in the synthesis of dimethyl ether, thereby avoiding the problem of excessive ethylene and propylene in dimethyl ether caused by high ethanol and propanol content in methanol, and the methanol and esters produced by the distillation system are directly sent back to the hydrogenation system for continued reaction and no longer participate in the synthesis of dimethyl ether, which will reduce the ethylene and propylene contents in dimethyl ether, thereby extending the service life of the carbonylation catalyst.

[0016] 2. In the present invention, crude alcohol is distilled inside the distillation tower, and the methanol and methyl acetate mixture at the top of the tower enters the fourth return pipe, passes through the third return pipe and the second return pipe in sequence into the first pump body for pressurization, enters the connecting pipe through the first return pipe, and enters the interior of the refining reactor together with the fresh methyl acetate and hydrogen mixture, so that methanol circulates in the system and no longer participates in the dimethyl ether synthesis process. The mixture of methanol and methyl acetate is recycled to prevent these impurities from affecting the dimethyl ether product.

[0017] 3. In the present invention, the fourth feed pipe and the third return pipe are both spirally distributed inside the heat exchange tube. The third return pipe exchanges heat with the material transported inside the fourth feed pipe. The waste heat of the steam in the mixture of methanol and methyl acetate can preheat the crude alcohol, increase the feed temperature of the crude alcohol, reduce the energy consumption of the distillation process, and at the same time reduce the heat of the mixture of methanol and methyl acetate itself, preventing the overheated mixture of methanol and methyl acetate from entering the interior of the heat exchange tube and affecting the reaction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flow chart of a method for extending the service life of a carbonylation catalyst according to the present invention; Figure 2 It is a schematic diagram of the first three-dimensional structure of a circulating heat exchange device of a method for extending the service life of a carbonylation catalyst according to the present invention; Figure 3 A schematic diagram of a second three-dimensional structure of a circulating heat exchange device in a method for extending the service life of a carbonylation catalyst according to the present invention; Figure 4 The figure is a schematic diagram of the internal cross-sectional structure of a circulating feeding mechanism of a method for extending the service life of a carbonylation catalyst of the present invention; Figure 5 A schematic diagram of the connection structure of the third return pipe and the fourth feed pipe in a method for extending the service life of a carbonylation catalyst according to the present invention; Figure 6 The present invention is a schematic diagram of the internal cross-sectional structure of a hydrogenation reaction mechanism for a method for extending the service life of a carbonylation catalyst.

[0019] In the figure: 1. fixed base; 2. distillation tower; 3. circulating feeding mechanism; 31. heat exchange cylinder; 32. first feeding pipe; 33. first return pipe; 34. first pump body; 35. second return pipe; 36. second feeding pipe; 37. second pump body; 38. third feeding pipe; 39. third return pipe; 310. fourth feeding pipe; 311. fourth return pipe; 4. hydrogenation reaction mechanism; 41. refining reactor; 42. mixing blades; 43. rotating rod; 44. driving motor; 45. annular pipe; 46. connecting pipe; 47. catalyst packing rack. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only 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.

[0021] Example 1: Reference Figure 1 A method for extending the service life of a carbonylation catalyst comprises the following steps: Step 1: dimethyl ether synthesis: purchased methanol is transported to the dimethyl ether reactor through a pipeline and reacts to generate dimethyl ether under the action of a specific catalyst; Methanol is the starting material of the reaction. Its quality and supply stability have a great impact on the subsequent links of the entire process. It is necessary to ensure that its purity and impurity content meet the production requirements. The specific catalyst is one of γ-alumina and ZSM-5 molecular sieve; the temperature inside the dimethyl ether reactor is set to 300°C and the pressure is set to 1MPa. Controlling the temperature and pressure within the set range can improve the conversion rate and selectivity of the reaction.

[0022] Step 2, carbonylation reaction: dimethyl ether and carbon monoxide are mixed and sent into a carbonylation reactor, where a carbonylation reaction is carried out under the action of a catalyst to generate methyl acetate; The carbonylation reaction comprises the following steps: 21. Carbon monoxide is drawn out from the carbon monoxide storage device and mixed with dimethyl ether in a certain molar ratio in a mixer. The mixer is usually provided with a static mixing element or a dynamic stirring device to promote the full and uniform mixing of dimethyl ether and carbon monoxide to ensure the mixing effect. The molar ratio of dimethyl ether to carbon monoxide is 1:1.3; The supply of carbon monoxide must ensure its purity and stable pressure. The presence of impurities will poison the catalyst and hinder the reaction. The purity of carbon monoxide must be tested. Gas chromatography analysis is used to detect whether carbon monoxide contains hydrogen sulfide and sulfur dioxide impurities. When impurities exceed the standard, adsorption and chemical absorption methods must be used for treatment; 22. The mixed gas passes through a buffer tank to stabilize the gas pressure and flow rate, reducing the impact of feed fluctuations on the reaction, and is then fed into a carbonylation reactor. A metering pump is used to continuously add the catalyst solution to the carbonylation reactor, controlling the amount of catalyst added to ensure that the catalyst concentration in the reaction system remains within an appropriate range; 23. Dimethyl ether and carbon monoxide undergo carbonylation reaction in the presence of a catalyst. Carbon monoxide molecules are adsorbed and dissociated on the catalyst surface to form active carbonyl species. Then dimethyl ether molecules are also adsorbed on the catalyst surface and react with the carbonyl species to generate methyl acetate after intermediate conversion. The internal temperature of the carbonylation reactor is set to 2000°C and the pressure is set to 5MPa.

[0023] Step 3, hydrogenation reaction: methyl acetate and hydrogen are mixed and sent into a hydrogenation reactor. The catalyst loaded inside the hydrogenation reactor causes methyl acetate and hydrogen to undergo a hydrogenation reaction. The hydrogen molecules dissociate into hydrogen atoms on the catalyst surface. The methyl acetate molecules are also adsorbed on the catalyst surface. The hydrogen atoms react with the carbonyl groups in the methyl acetate molecules to generate crude alcohol. Hydrogen is stored in high-pressure cylinders in the form of high-pressure gas. Before transporting hydrogen, the hydrogen pressure must be adjusted to an appropriate range through a pressure reducing device so that it can be mixed with methyl acetate later. The hydrogen storage and transportation equipment must be inspected and maintained regularly to ensure its sealing and safety, and to prevent safety accidents caused by hydrogen leakage; Use gas chromatograph to accurately detect the impurity content in hydrogen. The hydrogen sulfide content should be less than 1ppm and the carbon monoxide content should be less than 5ppm. If the impurities exceed the limit, it is necessary to start the hydrogen purification device to remove the impurities in the hydrogen. The internal temperature of the hydrogenation reactor was set at 210°C, the pressure was 5 MPa, and the molar ratio of methyl acetate and hydrogen was 1:5; Before installing the catalyst in the hydrogenation reactor, the inside of the reactor needs to be thoroughly cleaned to remove impurities and oil stains, and the catalyst should be evenly loaded into the hydrogenation reactor to ensure uniform gas distribution and catalyst stability. During the loading process, the catalyst particles should be avoided from breaking to ensure the integrity of the catalyst. The newly loaded catalyst needs to be activated before use to improve the catalytic activity of the catalyst.

[0024] Step 4, distillation separation: The crude alcohol is sent to a distillation system, and the components are separated by using the difference in boiling points of the components in the mixture. A mixture of methanol and methyl acetate is separated at the top of the tower, and ethanol is separated at the bottom of the tower; For crude alcohol containing multiple components such as methanol, methyl acetate, ethanol and other impurities, the feed position is selected in the middle and upper part of the distillation system so that each component has enough separation space in the distillation system; Step 5, Circulation reaction: The methanol and methyl acetate mixture separated from the distillation system is pressurized by a pressure pump, mixed with fresh methyl acetate and hydrogen, and sent into the hydrogenation reactor for reaction.

[0025] The cycle reaction includes the following steps: 51. The mixture of methanol and methyl acetate separated from the top of the distillation system is firstly led out through a pipeline, and a flow regulating valve is installed on the pipeline to control the amount of the mixture of methanol and methyl acetate led out; 52. The drawn methanol and methyl acetate mixture is sent to a circulating heat exchange device for heat exchange. The mixture after heat exchange enters a pressure pump to adjust the pressure of the mixture. The pressure of the mixture is adjusted to 3-6 MPa to match the hydrogenation reaction pressure; 53. Mix the pressurized methanol and methyl acetate mixture with fresh methyl acetate and hydrogen, and send the mixture into a hydrogenation reactor for hydrogenation reaction with a catalyst; When methanol is directly involved in the synthesis of dimethyl ether, since methanol contains ethanol and propanol impurities, these impurities will cause side reactions in the process of dimethyl ether synthesis to generate ethylene and propylene impurities, affecting the product quality of dimethyl ether. By recycling the mixture of methanol and methyl acetate, methanol is no longer allowed to participate in the synthesis of dimethyl ether, and the influence of these impurities on the dimethyl ether product is eliminated from the source. The recycling of methanol in the system improves the utilization rate of methanol. Methanol that cannot be effectively utilized due to impurity problems can be recycled to participate in hydrogenation reactions and other processes, thereby achieving maximum utilization of resources.

[0026] Example 2: Reference Figure 2 - Figure 6As shown: the circulating heat exchange device includes a circulating feeding mechanism 3, a fixed base 1 is installed at the bottom of the circulating feeding mechanism 3, the circulating feeding mechanism 3 includes a heat exchange tube 31, a third return pipe 39 and a fourth feed pipe 310 are installed inside the heat exchange tube 31, one end of the third return pipe 39 is fixedly connected to the fourth return pipe 311, one end of the fourth return pipe 311 passes through the top of the heat exchange tube 31, the other end of the third return pipe 39 is fixedly connected to the second return pipe 35, one end of the second return pipe 35 is fixedly connected to the third return pipe 39, and one end of the third return pipe 39 is fixedly connected to the fourth return pipe 311. A pump body 34, one side of the first pump body 34 is fixedly connected to one side of the fixed base 1, one end of the second return pipe 35 is fixedly connected to the first return pipe 33; one end of the fourth feeding pipe 310 is fixedly connected to the first feeding pipe 32, one end of the first feeding pipe 32 passes through one side of the heat exchange tube 31, the other end of the fourth feeding pipe 310 is fixedly connected to the third feeding pipe 38, one end of the third feeding pipe 38 passes through the heat exchange tube 31 and is fixedly connected to the second pump body 37, one side of the second pump body 37 is fixedly connected to the fixed base 1. On one side of the base 1, one end of the second pump body 37 is fixedly connected to the second feeding pipe 36, and one end of the second feeding pipe 36 is installed with a hydrogenation reaction mechanism 4; the hydrogenation reaction mechanism 4 includes a refining reactor 41, the bottom of the refining reactor 41 is fixedly connected to one side of the fixed base 1, the top of the refining reactor 41 is fixedly connected to a driving motor 44, the output end of the driving motor 44 passes through the top of the refining reactor 41 and is fixedly connected to a rotating rod 43, the outside of the rotating rod 43 is fixedly connected to a mixing blade 42, the inside of the refining reactor 41 is fixedly connected to a catalyst packing rack 47, the bottom end of the refining reactor 41 is fixedly connected to one end of the second feeding pipe 36, one end of the first return pipe 33 is fixedly connected to a connecting pipe 46, and one end of the connecting pipe 46 passes through one side of the refining reactor 41 and is fixedly connected to an annular pipe 45; the other end of the fourth return pipe 311 is fixedly connected to the distillation tower 2, the bottom of the distillation tower 2 is fixedly connected to one side of the fixed base 1, and the outside of the distillation tower 2 is fixedly connected to the other end of the first feeding pipe 32.

[0027] In this embodiment, methyl acetate and hydrogen are fed into the interior of the refining reactor 41 through the connecting pipe 46 and the annular pipe 45. The annular pipe 45 is annular in design, which increases the range of methyl acetate and hydrogen entering the interior of the refining reactor 41. A catalyst filling rack 47 is provided inside the refining reactor 41 for loading the catalyst. The driving motor 44 drives the rotating rod 43 to rotate, and the mixing blades 42 move accordingly to mix the gas inside the refining reactor 41. The mixture undergoes a hydrogenation reaction with the loaded catalyst through the catalyst filling rack 47 to generate crude alcohol. The second pump body 37 works to drive the crude alcohol into the second feeding pipe 36 connected to the bottom of the refining reactor 41, and sequentially passes through the third feeding pipe 38, the fourth feeding pipe 310 and the first feeding pipe 32 to enter the distillation tower 2 from the middle and upper part of the distillation tower 2; The crude alcohol is distilled inside the distillation tower 2, and methanol and methyl acetate are continuously enriched in the steam. As the steam rises to the top of the tower, ethanol and high-boiling impurities are continuously enriched in the liquid. As the liquid flows to the bottom of the tower, the methanol and methyl acetate mixture at the top of the tower enters the fourth return pipe 311, and successively passes through the third return pipe 39 and the second return pipe 35 to enter the first pump body 34. The first pump body 34 is a pressure pump that can pressurize the mixture. The pressurized mixture passes through the first return pipe 33 and enters the connecting pipe 46, and enters the refining reactor 41 together with the fresh methyl acetate and hydrogen mixture, so that methanol circulates in the system and no longer participates in the dimethyl ether synthesis process. The mixture of methanol and methyl acetate is recycled to prevent these impurities from affecting the dimethyl ether product. At the same time, when the crude alcohol is transported from the hydrogenation reaction mechanism 4 to the inside of the distillation tower 2, the section of the fourth feed pipe 310 through which the crude alcohol passes is spirally distributed inside the heat exchange tube 31. When the mixture at the top of the tower is circulated into the hydrogenation reaction mechanism 4 to participate in the reaction again, the section of the third return pipe 39 through which the mixture of methanol and methyl acetate passes is spirally distributed inside the heat exchange tube 31, and the third return pipe 39 and the fourth feed pipe 310 are kept in contact, so that the third return pipe 39 and the materials transported inside the fourth feed pipe 310 can exchange heat. The waste heat of the steam in the methanol and methyl acetate mixture can preheat the crude alcohol, increase the feed temperature of the crude alcohol, and reduce the energy consumption of the distillation process. At the same time, the heat of the methanol and methyl acetate mixture itself is reduced, preventing the overheated methanol and methyl acetate mixture from entering the inside of the heat exchange tube 31, where the temperature difference between the mixture and the fresh methyl acetate and hydrogen mixture is large, affecting the reaction effect.

[0028] The use method and working principle of the device: The present invention uses purchased methanol as the starting material, and with the help of the coordinated operation of multiple reactors and separation equipment, sequentially carries out dimethyl ether synthesis, carbonylation reaction, hydrogenation reaction, and distillation separation operations, and finally achieves product production and recycling of raw materials. The purchased methanol is transported to the dimethyl ether reactor through a pipeline, and the methanol reacts in the reactor to generate dimethyl ether. Subsequently, the generated dimethyl ether is mixed with carbon monoxide and enters the carbonylation reactor to react to generate methyl acetate; Next, methyl acetate and hydrogen are fed into the interior of the refining reactor 41 through the connecting pipe 46 and the annular pipe 45. A catalyst filling rack 47 is provided inside the refining reactor 41 for loading the catalyst. The driving motor 44 drives the rotating rod 43 to rotate, and the mixing blades 42 move accordingly to mix the gas inside the refining reactor 41. The mixture undergoes a hydrogenation reaction with the loaded catalyst through the catalyst filling rack 47 to generate crude alcohol. The second pump body 37 works to drive the crude alcohol into the second feeding pipe 36, and then sequentially enters through the third feeding pipe 38, the fourth feeding pipe 310 and the first feeding pipe 32. In the distillation tower 2, the crude alcohol is distilled inside the distillation tower 2, and methanol and methyl acetate are continuously enriched in the steam. As the steam rises to the top of the tower, ethanol and high-boiling impurities are continuously enriched in the liquid. As the liquid flows to the bottom of the tower, the methanol and methyl acetate mixture at the top of the tower enters the fourth return pipe 311, and enters the first pump body 34 through the third return pipe 39 and the second return pipe 35 in sequence for pressurization. The pressurized mixture enters the connecting pipe 46 through the first return pipe 33, and enters the refining reactor 41 together with the fresh methyl acetate and hydrogen mixture, so that methanol circulates in the system; The fourth feed pipe 310 and the third return pipe 39 are both spirally distributed inside the heat exchange tube 31, and the third return pipe 39 and the fourth feed pipe 310 are kept in close contact, so that the third return pipe 39 and the material transported inside the fourth feed pipe 310 can exchange heat, and the waste heat of the steam in the methanol and methyl acetate mixture can preheat the crude alcohol.

[0029] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for extending the service life of a carbonylation catalyst, characterized in that: The following steps are involved: S1. Dimethyl ether synthesis: purchased methanol is transported to the dimethyl ether reactor through a pipeline and reacts to generate dimethyl ether under the action of a specific catalyst; S2, carbonylation reaction: dimethyl ether and carbon monoxide are mixed and sent into a carbonylation reactor, where a carbonylation reaction is carried out under the action of a catalyst to generate methyl acetate; S3, hydrogenation reaction: methyl acetate and hydrogen are mixed and sent into a hydrogenation reactor, and the catalyst loaded inside the hydrogenation reactor causes methyl acetate and hydrogen to undergo a hydrogenation reaction to generate crude alcohol; S4, distillation separation: the crude alcohol is sent to a distillation system, and the components are separated by using the difference in boiling points of the components in the mixture, a mixture of methanol and methyl acetate is separated at the top of the tower, and ethanol is separated at the bottom of the tower; S5. Circulation reaction: The methanol and methyl acetate mixture separated from the distillation system is pressurized by a pressure pump, mixed with fresh methyl acetate and hydrogen, and sent into the hydrogenation reactor for reaction.

2. A method for extending the service life of a carbonylation catalyst according to claim 1, characterized in that: In step S1, the specific catalyst is one of γ-alumina and ZSM-5 molecular sieve.

3. A method for extending the service life of a carbonylation catalyst according to claim 2, characterized in that: In step S1, the temperature inside the dimethyl ether reactor is set to 250-350°C, and the pressure is set to 0.5-1.5 MPa.

4. A method for extending the service life of a carbonylation catalyst according to claim 3, characterized in that: In step S2, the carbonylation reaction comprises the following steps: S21, drawing carbon monoxide from the carbon monoxide storage device, and feeding it into a mixer for mixing with dimethyl ether in a certain molar ratio, wherein the molar ratio of dimethyl ether to carbon monoxide is 1:1.2-1:1.5; S22, the mixed gas is passed through a buffer tank to stabilize the pressure and flow of the gas, and then sent to the carbonylation reactor, and the catalyst solution is continuously added to the carbonylation reactor using a metering pump; S23, dimethyl ether and carbon monoxide undergo carbonylation reaction under the action of a catalyst to generate methyl acetate. The internal temperature of the carbonylation reactor is set to 150-250°C and the pressure is set to 2-8MPa.

5. A method for extending the service life of a carbonylation catalyst according to claim 4, characterized in that: In step S3, the internal temperature of the hydrogenation reactor is set to 180-260° C., the pressure is 3-6 MPa, and the molar ratio of the mixture of methyl acetate and hydrogen is 1:4-1:

6.

6. A method for extending the service life of a carbonylation catalyst according to claim 5, characterized in that: In step S5, the cyclic reaction comprises the following steps: S51, the mixture of methanol and methyl acetate separated from the top of the distillation system is firstly led out through a pipeline, and a flow regulating valve is installed on the pipeline to control the lead-out amount of the mixture of methanol and methyl acetate; S52, the drawn methanol and methyl acetate mixture is sent to a circulating heat exchange device for heat exchange, and the mixture after heat exchange enters a pressure pump to adjust the pressure of the mixture to 3-6MPa; S53, mixing the pressurized methanol and methyl acetate mixture with fresh methyl acetate and hydrogen, and sending the mixture into a hydrogenation reactor to carry out a hydrogenation reaction with a catalyst.

7. A method for extending the service life of a carbonylation catalyst according to claim 6, characterized in that: The circulating heat exchange device comprises a circulating feeding mechanism (3), a fixed base (1) is installed at the bottom of the circulating feeding mechanism (3), the circulating feeding mechanism (3) comprises a heat exchange cylinder (31), a third return pipe (39) and a fourth feed pipe (310) are installed inside the heat exchange cylinder (31), one end of the third return pipe (39) is fixedly connected to the fourth return pipe (311), one end of the fourth return pipe (311) passes through the top of the heat exchange cylinder (31), the other end of the third return pipe (39) is fixedly connected to the second return pipe (35), one end of the second return pipe (35) is fixedly connected to the first pump body (34), one side of the first pump body (34) is fixedly connected to one side of the fixed base (1), and one end of the second return pipe (35) is fixedly connected to the first return pipe (33).

8. A method for extending the service life of a carbonylation catalyst according to claim 7, characterized in that: One end of the fourth feeding pipe (310) is fixedly connected to the first feeding pipe (32), one end of the first feeding pipe (32) passes through one side of the heat exchange tube (31), the other end of the fourth feeding pipe (310) is fixedly connected to the third feeding pipe (38), one end of the third feeding pipe (38) passes through the heat exchange tube (31) and is fixedly connected to the second pump body (37), one side of the second pump body (37) is fixedly connected to one side of the fixed base (1), one end of the second pump body (37) is fixedly connected to the second feeding pipe (36), and one end of the second feeding pipe (36) is installed with a hydrogenation reaction mechanism (4).

9. A method for extending the service life of a carbonylation catalyst according to claim 8, characterized in that: The hydrogenation reaction mechanism (4) comprises a refining reactor (41), the bottom of the refining reactor (41) is fixedly connected to one side of the fixed base (1), the top of the refining reactor (41) is fixedly connected to a driving motor (44), the output end of the driving motor (44) passes through the top of the refining reactor (41) and is fixedly connected to a rotating rod (43), the outside of the rotating rod (43) is fixedly connected to a mixing blade (42), the inside of the refining reactor (41) is fixedly connected to a catalyst packing frame (47), the bottom end of the refining reactor (41) is fixedly connected to one end of the second feeding pipe (36), one end of the first return pipe (33) is fixedly connected to a connecting pipe (46), and one end of the connecting pipe (46) passes through one side of the refining reactor (41) and is fixedly connected to an annular pipe (45).

10. A method for extending the service life of a carbonylation catalyst according to claim 7, characterized in that: The other end of the fourth return pipe (311) is fixedly connected to a distillation tower (2), the bottom of the distillation tower (2) is fixedly connected to one side of the fixed base (1), and the outer side of the distillation tower (2) is fixedly connected to the other end of the first feed pipe (32).

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