A pilot-scale system, containerized pilot plant, and production method for the CO esterification of methyl formate

Abstract

This application discloses a pilot-scale system, a containerized pilot-scale unit, and a production method for the production of methyl formate via CO esterification, belonging to the field of carbon monoxide esterification of ester-based chemicals. The containerized pilot-scale unit adopts a skid-mounted design, resulting in a small footprint, easy mobility, and quick, simple, and convenient on-site installation, meeting the temporary needs of pilot-scale units in various situations. The production method includes mixing, pressurization, esterification, reaction, separation, distillation, product storage, utilities, waste treatment, detection, and DCS control. It allows for the investigation and verification of factors within and between each process unit, as well as environmental protection, byproducts, analysis, detection, and control. This not only enables small-scale continuous production of methyl formate but also, based on the results of the pilot-scale experiment, can promote the scale-up and even industrialization of this technology.

Description

Technical Field

[0001] This application relates to a pilot-scale system, containerized pilot-scale apparatus and production method for the production of methyl formate by CO esterification, belonging to the field of esterification of ester chemicals by carbon monoxide esterification. Background Technology

[0002] Methyl formate is an important C1 chemical product and a crucial intermediate in organic synthesis with a wide range of applications. In the chemical industry, it is a vital intermediate for the production of formic acid, amides, and other products, used to manufacture formic acid, formamide, dimethylformamide, methyl methacrylate, high-purity CO, and formate salts. It is also a raw material for the synthesis of pharmaceutical drugs such as sulfonated methylpyrimidine, sulfonated methoxypyrimidine, and the antitussive dextromethorphan. Furthermore, it can be used as a fumigant and bactericide for treating tobacco, dried fruits, and grains.

[0003] The main methods for producing methyl formate include: methanol formate esterification, liquid-phase methanol carbonylation, methanol dehydrogenation, methanol oxidative dehydrogenation, formaldehyde dimerization, and direct synthesis from syngas. Currently, the main industrial production technology for methyl formate, both domestically and internationally, utilizes the liquid-phase methanol carbonylation process. The liquid-phase methanol carbonylation process involves the carbonylation reaction of methanol and carbon monoxide with sodium methoxide as a catalyst to produce methyl formate. Specifically, carbon monoxide and methanol are mixed with sodium methoxide and subjected to a carbonylation reaction under specific pressure and temperature to generate methyl formate. This process has certain technical limitations: 1) Sodium methoxide is sensitive to water, therefore the water content in the raw methanol must be below the ppm level; 2) Sodium methoxide is a strong alkali, corroding equipment, resulting in high reactor investment costs; it also generates solid waste, which can easily clog valves and cause operational difficulties; 3) This reaction is a homogeneous reaction, requiring further separation of the catalyst and product, which is cumbersome; 4) This method cannot achieve continuous production of methyl formate.

[0004] To address the problems of existing liquid-phase processes and the increasing demand for methyl formate and its downstream products, numerous domestic and international institutions are developing gas-phase CO direct esterification technology for the production of methyl formate. However, on the one hand, most of the CO esterification production technologies and corresponding catalysts currently under development are still in the laboratory research stage, and there are no reports on pilot-scale research and industrial-scale trials of this technology. Generally speaking, at least several thousand hours of pilot-scale verification is a necessary process for the industrialization of this technology. On the other hand, current pilot-scale evaluation devices are usually installed in fixed locations, but many places are not suitable for constructing permanent buildings, and the demand for temporary use of pilot-scale evaluation devices is increasing. Summary of the Invention

[0005] The purpose of this invention is to provide a containerized pilot plant for the complete process of CO esterification to produce methyl formate.

[0006] According to the first aspect of this application, a pilot-scale system for the CO esterification of methyl formate is provided.

[0007] A pilot-scale system for the production of methyl formate by CO esterification, comprising a methyl nitrite gas pipeline, a nitrogen gas pipeline, a carbon monoxide gas pipeline, a hydrogen gas pipeline, an oxygen gas pipeline, a methanol pipeline, a circulating gas pressurization unit 1, an esterification tower 2, a preheater 3, a reactor 4, a hydrogen removal reactor 5, an eluent tower 6, a first distillation tower 7, a dimethyl oxalate storage tank 8, a second distillation tower 9, a third distillation tower 10, a methyl formate storage tank 11, a methyl acetal storage tank 12, a methanol storage tank 13, a relaxation unit 14, and a tail gas absorption tank 15;

[0008] Among them, the methyl nitrite gas pipeline, nitrogen pipeline, carbon monoxide gas pipeline, hydrogen pipeline and circulating gas pipeline are connected to the inlet of the circulating gas booster unit 1, the outlet of the circulating gas booster unit 1 and the oxygen gas pipeline are connected to the inlet of the middle and lower end of the esterification tower, and the methanol pipeline is connected to the upper end of the esterification tower 2 through a liquid pump.

[0009] The inlet of preheater 3 is connected to the outlet at the top of esterification tower 2, the inlet of reactor 4 is connected to the outlet of preheater 3, the inlet of dehydrogenation reactor 5 is connected to the outlet of reactor 4, the lower inlet of elution tower 6 is connected to the outlet of dehydrogenation reactor 5, and the top of elution tower 6 is directly connected to the inlet of pressurization unit 1, and connected to tail gas absorption tank 15 after passing through venting unit 14.

[0010] The material inlet of the first distillation column 7 is connected to the bottom of the elution column 6 via a feed pump. The bottom outlet of the first distillation column 7 is connected to the dimethyl oxalate storage tank 8. The material inlet of the second distillation column 9 is connected to the top outlet of the first distillation column 7 via a feed pump. The methanol storage tank 13 is connected to the bottom outlet of the second distillation column 9 via a feed pump. The material inlet of the third distillation column 10 is connected to the top outlet 9 of the second distillation unit via a feed pump. The top outlet of the third distillation column 10 is connected to the methyl formate storage tank 11. The bottom outlet of the third distillation column 10 is connected to the methyl acetal storage tank 12.

[0011] Optionally, the reactor 4 is a tubular reactor with a multi-section structural design;

[0012] Multiple temperature control points are set at different axial heights inside reactor 4 to monitor the temperature of each catalyst bed inside reactor 4.

[0013] The radial distribution position of the temperature sensors inside the tube of reactor 4 is adjustable, which is used to simultaneously monitor the radial temperature distribution inside the catalyst bed.

[0014] The reactor 4 is connected to the heat transfer oil system via a quick-opening flange.

[0015] Multiple temperature control points are set at different axial heights inside the reactor to monitor the temperature of each catalyst bed. The radial distribution of temperature sensors inside the tube is adjustable, allowing simultaneous monitoring of the radial temperature distribution within the catalyst bed. The reactor is connected to the heat transfer oil system via a quick-opening flange, which is easy to disassemble and suitable for studying catalyst loading schemes. At the same time, the connecting flange between the heat transfer oil and the reactor shell has sufficient space, allowing for replacement of reactors of different sizes.

[0016] Reactor 4 is a fixed-bed tubular reactor with a multi-stage structure. It can not only perform conventional catalyst performance evaluation, but also study and verify the effects of catalyst particle size, packing scheme, heat transfer, and reactor structure.

[0017] Optionally, the circulating gas booster unit 1 includes a mixer, a buffer tank assembly, and a compressor assembly;

[0018] The esterification tower 2 includes an esterification reaction tower and supporting condensation devices and storage tank groups.

[0019] Optionally, the release unit 14 includes a pneumatic flow regulating valve, a flow meter, and a pressure gauge.

[0020] Optionally, the distillation column includes a distillation column body and its associated preheater, condenser and reflux tank.

[0021] According to a second aspect of this application, a containerized pilot plant for the production of methyl formate by CO esterification is provided. Employing a containerized skid-mounted design, the equipment occupies a small area, is easy to move, and allows for quick, simple, and convenient on-site installation, meeting the temporary needs of pilot plants in a wider range of situations.

[0022] A containerized pilot plant for the production of methyl formate by CO esterification, the pilot plant comprising a container, a CO esterification pilot system for the production of methyl formate, a utility unit, an automation control unit, and an analysis unit;

[0023] The CO esterification pilot-scale system for producing methyl formate, the utility unit, the automation control unit, and the analysis unit are all housed inside the container.

[0024] The CO esterification pilot-scale system for producing methyl formate is selected from the pilot-scale system described above.

[0025] Optionally, the utility unit includes a heating circulation system, a cooling water circulation system, a chilled water circulation system, a vacuum pump, and an air compressor;

[0026] The heating circulation system is connected to the preheater 3, reactor 4, first distillation column 7, second distillation column 9, and third distillation column 10 via pipelines; the cooling water circulation system is connected to the compressor unit and the heat transfer oil system; the chilled water circulation system is connected to the esterification column 2, the elution column, and the methyl formate storage tank 11; and the vacuum pump is connected to the esterification column 2, reactor 4, and elution column 6.

[0027] Optionally, the heating circulation system uses heat transfer oil or steam, with a temperature range of 0~300 ℃.

[0028] Optionally, the chilled water circulation system uses an aqueous solution of ethylene glycol with a temperature range of -60 to 20 ℃.

[0029] Optionally, the automation control unit includes a detection unit, a control unit, and an execution unit;

[0030] The detection unit includes a remote pressure sensor, a remote liquid level sensor, and a remote temperature sensor; the control unit adopts a distributed control system; and the execution unit includes pneumatic and electric switching valves and electric heat tracing.

[0031] Optionally, the control unit includes a power distribution cabinet and a DCS-based control system.

[0032] Optionally, the analytical unit includes an online gas chromatograph, an online mass spectrometer, and a nitrogen oxide analyzer.

[0033] Optionally, the inlet and outlet of esterification tower 2, the inlet and outlet of reactor 4, and the top of elution tower 6 are all connected to an analytical unit for real-time online analysis.

[0034] Optionally, manual sampling ports are provided at the top and bottom of both the first distillation column 7 and the second distillation column 9.

[0035] Optionally, the equipment in the CO esterification pilot-scale system for producing methyl formate, the utility unit, the automation control unit, and the analysis unit is fixedly connected to the container by welding, bolting, or snap-fitting.

[0036] According to a third aspect of this application, a method for producing methyl formate by CO esterification is provided.

[0037] A method for producing methyl formate by CO esterification, wherein the production method employs the pilot-scale system described above;

[0038] Includes the following steps:

[0039] The circulating gas, methyl nitrite, nitrogen, carbon monoxide and hydrogen enter the circulating gas pressurization unit 1 and are pressurized. The pressurized mixed gas and oxygen enter the middle and lower end of the esterification tower 2. Then methanol enters the upper end of the esterification tower 2 through a fluid pump and reacts with the mixed gas in the esterification tower 2 to generate methyl nitrite.

[0040] The gas effluent from the upper end of esterification tower 2 enters preheater 3 for preheating. The preheated gas then enters reactor 4 to react with the catalyst. The effluent from the lower end of reactor 4 enters dehydrogenation reactor 5 for dehydrogenation, and then enters elution tower 6 for separation. It is absorbed by cold methanol, and the liquid product enters the first distillation tower 7 for gas-liquid separation via a liquid pump. The top product of the first distillation tower 7 enters the second distillation tower 9, and the bottom product of the first distillation tower 7 enters the dimethyl oxalate storage tank 8. The top product of the second distillation tower 9 enters the third distillation tower 10, and the bottom product of the second distillation tower 9 enters the methanol storage tank 13. The top product of the third distillation tower 10 enters the methyl formate storage tank 11, and the bottom product of the third distillation tower enters the methyl acetal storage tank 12.

[0041] Optionally, the operating parameters of the circulating gas booster unit 1 are as follows: methyl nitrite flow rate 0~16 SLPM, carbon monoxide flow rate 0~25 SLPM; nitrogen flow rate 0~30 SLPM; hydrogen flow rate 0~8 SLPM, and the design pressure is 1 MPa;

[0042] The operating parameters of esterification tower 2 are as follows: methanol flow rate 0~1.68 Kg / h, circulating gas flow rate 0~80 SLPM, oxygen flow rate 0~4 SLPM, design operating temperature 0~200 ℃, and operating pressure 0~1 Mpa;

[0043] The operating parameters of reactor 4 are as follows: operating space velocity is 0~5000 h⁻¹ -1 The maximum design temperature is 200℃;

[0044] The operating parameters of the first distillation column 7, the second distillation column 9, and the third distillation column 10 are as follows: height-to-diameter ratio of 26~65:1, operating temperature of 0~200 ℃, and design pressure of 0.4 MPa.

[0045] Optionally, the length of reactor 4 is 0.5~10 m, the inner diameter of a single tube is 10~50 mm, the material is 304, 304L, 316, or 316L, and the pressure resistance range is 0~5 MPa.

[0046] In this application, the reaction principle for the direct esterification of CO to produce methyl formate is as follows:

[0047] 2CO+2CH3ONO+H2=2HCOOCH3+2NO(1)

[0048] 2CH3ONO+CH3OH→CH3OCH2OCH3+H2O+2NO(2)

[0049] 2CO + CH3ONO = (CH3OCO)2 + 2NO (3)

[0050] 2CH3ONO + H2 = 2CH3OH + 2NO (4)

[0051] 2NO+2CH3OH+0.5O2=2CH3ONO+H2O(5)

[0052] Reaction (1) is the main reaction for the production of methyl formate by CO esterification, which is carried out on the catalyst surface in the reactor. The catalyst is a noble metal catalyst. Reaction (2) and (3) are side reactions in the production of methyl formate, which are carried out on the catalyst surface in the reactor. Reaction (4) is the main reaction in the dehydrogenation reactor, which is carried out on the catalyst surface. Reaction (5) is the reaction for the regeneration of tail gas nitric oxide into methyl nitrite, which is carried out in the esterification tower.

[0053] According to the fourth aspect of this application, a complete process method for producing methyl formate by CO esterification is provided. This complete process includes mixing, pressurization, esterification, reaction, separation, distillation, product storage, utilities, waste treatment, detection, and DCS control. It allows for the examination and verification of factors within each process unit, between process units, and in relation to environmental protection, byproducts, analysis, detection, and control.

[0054] A complete production method for producing methyl formate by CO esterification, wherein the complete production method uses the pilot-scale equipment described above.

[0055] Includes the following steps:

[0056] S1. Check all settings on all hardware devices and control software;

[0057] S2. Start the utility unit, prepare gas and liquid raw materials, ensure that the pressure and liquid level on each storage tank are normal, and fill the reactor with catalyst;

[0058] S3. Turn on the analysis unit and power on all instruments, pumps, heaters, heating cables, and other equipment; supply the necessary cooling water, chilled water, heat transfer oil, and instrument air for the utilities; and set all manual and automatic valves to their initial values.

[0059] S4. Check for airtightness and begin vacuum purging;

[0060] S5. First, introduce nitrogen gas and start the circulating gas pressurization unit 1 and the washing tower 6;

[0061] S6. After the circulating gas pressurization unit 1 is running stably, carbon monoxide, methyl nitrite and hydrogen are introduced and the temperature is raised to the reaction temperature. At the same time, the process parameters such as temperature, pressure, liquid level, flow rate and composition of each process unit in the system are monitored until the reactor 4 is running normally.

[0062] S7. After reactor 4 is operating normally, start esterification tower 2 so that the nitric oxide in the circulating gas can be regenerated into the raw material gas methyl nitrite.

[0063] S8. When the washing tower 6 reaches the preset liquid level, the first distillation tower 7, the second distillation tower 9, and the third distillation tower 10 can be turned on, and the heating and feeding of the corresponding towers can be turned on to make the distillation towers operate stably.

[0064] S9. When the pilot plant reaches steady-state operation, on the one hand, methyl formate products are gradually collected, and on the other hand, the process parameters of each process unit in the pilot plant are gradually collected and optimized.

[0065] When the pilot plant reaches steady-state operation, on the one hand, methyl formate products can be collected gradually, and on the other hand, the process parameters of each process unit in the pilot plant can be optimized and explored. The catalyst loading scheme in the reactor, the radial temperature distribution in each bed, the axial temperature distribution on different beds, and the catalyst performance (selectivity, conversion rate, space-time yield) can be analyzed and studied.

[0066] The beneficial effects that this application can produce include:

[0067] 1) The containerized pilot-scale unit for CO esterification to methyl formate provided in this application adopts a skid-mounted container structure, resulting in a small footprint and rapid, simple, and convenient transportation and on-site installation, meeting the temporary needs of pilot-scale units in various situations. It employs a fixed-bed tubular reactor with a multi-stage structure, allowing for not only conventional catalyst performance evaluation but also research and verification of the effects of catalyst particle size, packing scheme, heat transfer, and reactor structure. The automated DCS control system significantly reduces labor costs and facilitates long-term operation of the unit, making it suitable for research institutes, enterprises, universities, and other institutions to conduct scale-up process experiments and catalyst performance evaluations for CO esterification technology.

[0068] 2) The complete production process of methyl formate via CO esterification provided in this application includes pressurization, esterification, mixing, reaction, separation, distillation, product storage, utilities, waste treatment, detection, and DCS control. It allows for the investigation and verification of factors such as within each process unit (esterification tower, reactor, elution tower, distillation tower), between process units, environmental protection, byproducts, analytical testing, and DCS control. This not only enables small-scale continuous production of methyl formate but also, based on the results of pilot-scale experiments, promotes the scale-up and even industrialization of this technology. Attached Figure Description

[0069] Figure 1 A schematic diagram of the process flow for producing methyl formate by CO esterification.

[0070] Figure 2 A schematic diagram of the exterior design of a containerized pilot plant for the production of methyl formate by CO esterification.

[0071] Figure 3 A field photo of a containerized pilot plant for the production of methyl formate by CO esterification.

[0072] Figure 4 This is a design drawing for a fixed-bed tubular reactor.

[0073] List of components and reference numerals:

[0074] 1. Circulating gas booster unit; 2. Esterification tower; 3. Preheater

[0075] 4. Reactor; 5. Hydrogen removal reactor; 6. Scrubber.

[0076] 7. First distillation column; 8. Dimethyl oxalate storage tank; 9. Second distillation column

[0077] 10. Third distillation column; 11. Methyl formate storage tank; 12. Methyl acetal storage tank.

[0078] 13. Methanol storage tank; 14. Release unit; 15. Tail gas absorption tank Detailed Implementation

[0079] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0080] Unless otherwise specified, the raw materials and catalysts used in the embodiments of this application were all purchased commercially.

[0081] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0082] Example 1

[0083] like Figure 1 The diagram shown is a schematic of the process flow for the production of methyl formate by CO esterification. It includes pipelines for methyl nitrite gas, nitrogen gas, carbon monoxide gas, hydrogen gas, oxygen gas, and methanol; circulating gas booster unit 1; esterification tower 2; preheater 3; reactor 4; dehydrogenation reactor 5; washing tower 6; first distillation tower 7; dimethyl oxalate storage tank 8; second distillation tower 9; third distillation tower 10; methyl formate storage tank 11; methyl acetal storage tank 12; methanol storage tank 13; release unit 14; and tail gas absorption tank 15.

[0084] Among them, the methyl nitrite gas pipeline, nitrogen pipeline, carbon monoxide gas pipeline, hydrogen pipeline and circulating gas pipeline are connected to the inlet of the circulating gas booster unit 1, the outlet of the circulating gas booster unit 1 and the oxygen gas pipeline are connected to the inlet of the middle and lower end of the esterification tower, and the methanol pipeline is connected to the upper end of the esterification tower 2 through a liquid pump.

[0085] The inlet of preheater 3 is connected to the outlet at the top of esterification tower 2, the inlet of reactor 4 is connected to the outlet of preheater 3, the inlet of dehydrogenation reactor 5 is connected to the outlet of reactor 4, the lower inlet of elution tower 6 is connected to the outlet of dehydrogenation reactor 5, and the top of elution tower 6 is directly connected to the inlet of pressurization unit 1, and connected to tail gas absorption tank 15 after passing through venting unit 14.

[0086] The material inlet of the first distillation column 7 is connected to the bottom of the elution column 6 via a feed pump. The bottom outlet of the first distillation column 7 is connected to the dimethyl oxalate storage tank 8. The material inlet of the second distillation column 9 is connected to the top outlet of the first distillation column 7 via a feed pump. The methanol storage tank 13 is connected to the bottom outlet of the second distillation column 9 via a feed pump. The material inlet of the third distillation column 10 is connected to the top outlet 9 of the second distillation unit via a feed pump. The top outlet of the third distillation column 10 is connected to the methyl formate storage tank 11. The bottom outlet of the third distillation column 10 is connected to the methyl acetal storage tank 12.

[0087] The circulating gas, methyl nitrite, nitrogen, carbon monoxide and hydrogen enter the circulating gas pressurization unit 1 and are pressurized. The pressurized mixed gas and oxygen enter the middle and lower end of the esterification tower 2. Then methanol enters the upper end of the esterification tower 2 through a fluid pump and reacts with the mixed gas in the esterification tower 2 to generate methyl nitrite.

[0088] The gas effluent from the upper end of esterification tower 2 enters preheater 3 for preheating. The preheated gas then enters reactor 4 to react with the catalyst. The effluent from the lower end of reactor 4 enters dehydrogenation reactor 5 for dehydrogenation, and then enters elution tower 6 for separation. It is absorbed by cold methanol, and the liquid product enters the first distillation tower 7 for gas-liquid separation via a liquid pump. The top product of the first distillation tower 7 enters the second distillation tower 9, and the bottom product of the first distillation tower 7 enters the dimethyl oxalate storage tank 8. The top product of the second distillation tower 9 enters the third distillation tower 10, and the bottom product of the second distillation tower 9 enters the methanol storage tank 13. The top product of the third distillation tower 10 enters the methyl formate storage tank 11, and the bottom product of the third distillation tower enters the methyl acetal storage tank 12.

[0089] Figure 2 A schematic diagram of the exterior design of a containerized pilot plant for the production of methyl formate by CO esterification. Figure 3These are on-site photos of a containerized pilot plant for the CO esterification of methyl formate. The pilot plant includes a container, a CO esterification pilot system, utility units, an automation control unit, and an analysis unit. All components—the CO esterification pilot system, utility units, automation control unit, and analysis unit—are housed within the container. The equipment in these components is fixed to the container via welding, bolting, or snap-fit ​​connections.

[0090] The utility unit includes a heating circulation system, a cooling water circulation system, a chilled water circulation system, a vacuum pump, and an air compressor. The heating circulation system is connected to the preheater 3, reactor 4, first distillation column 7, second distillation column 9, and third distillation column 10 via pipelines. The cooling water circulation system is connected to the compressor unit and the heat transfer oil system. The chilled water circulation system is connected to the esterification column 2, the elution column, and the methyl formate storage tank 11. The vacuum pump is connected to the esterification column 2, reactor 4, and elution column 6.

[0091] The automation control unit includes a detection unit, a control unit, and an execution unit. The detection unit includes remote pressure sensors, remote level sensors, and remote temperature sensors. The control unit employs a distributed control system. The execution unit includes pneumatic and electric valves and electric heat tracing. The control unit includes a power distribution cabinet and a DCS-based control system.

[0092] The analytical unit includes an online gas chromatograph, an online mass spectrometer, and a nitrogen oxide analyzer. The inlet and outlet of esterification column 2, the inlet and outlet of reactor 4, and the top of elution column 6 are all connected to the analytical unit for real-time online analysis. Manual sampling ports are provided at the top and bottom of the first distillation column 7 and the second distillation column 9.

[0093] The release unit 14 includes a pneumatic flow regulating valve, a flow meter, and a pressure gauge.

[0094] The heating circulation system uses heat transfer oil with a temperature range of 0~300 ℃. The chilled water circulation system uses ethylene glycol aqueous solution with a temperature range of -60~20 ℃.

[0095] The parameters of the circulating gas booster unit are as follows: methyl nitrite flow rate 0~16 SLPM, carbon monoxide flow rate 0~25 SLPM; nitrogen flow rate 0~30 SLPM; hydrogen flow rate 0~8 SLPM; the pipeline mixer adopts type SV, with a design pressure of 1 MPa; the buffer tank has a design height of 0.5 meters, a height-to-diameter ratio of 5:1, and is made of 304L material, with an operating pressure of 0~1 MPa. During operation, the flow rates of methyl nitrite, carbon monoxide, nitrogen, and hydrogen are gradually adjusted according to the operating stage of the pilot plant (start-up, stable operation, or emergency shutdown). During normal operation, they are not all 0 simultaneously, but the flow rate of a single flow meter can be set to 0. In emergency situations, they will all be set to 0.

[0096] The esterification unit parameters are as follows: methanol flow rate 0~1.68 kg / h, circulating gas flow rate 0~80 SLPM, oxygen flow rate 0~4 SLPM, esterification tower material is 304L, operating temperature is 0~200℃, and operating pressure is 0~1 MPa. Through the esterification reaction, the total NO content is reduced to below 8%. During operation, the methanol flow rate, circulating gas flow rate, and oxygen flow rate are gradually adjusted according to the operating stage of the pilot plant (start-up, stable operation, or emergency shutdown). During normal operation, they are not all simultaneously at 0, but the flow rate of one flow meter can be set to 0. In emergency situations, they will all be set to 0.

[0097] The reactor equipment parameters are as follows: the heat exchanger's heat exchange area is 0.6 m². 3 The maximum design temperature is 200℃, the methyl formate reactor packing capacity is 1L, and the operating space velocity is 0~5000h. -1 After passing through a dehydrogenation reactor, the hydrogen level is reduced to below 100 ppm.

[0098] The parameters of the esterification tower equipment are as follows: the heat exchanger area is 0.36m². 2 The washing tower is designed with a pressure of 0.1 MPa and a temperature of 80℃.

[0099] The parameters of the distillation column equipment are as follows: the heat exchange area of ​​the preheater is 0.85m². 2 The design pressure is 0.4 MPa. The first and second distillation columns use 316L stainless steel with a height-to-diameter ratio of 50:1. The operating temperature is 0~200℃, the packing density is 50L, and the heat exchange area of ​​the preheater, condenser, and cooler is 0.36 m². 2 .

[0100] The reactor is a tubular reactor, 2 meters long, with each tube having an inner diameter of 26 mm, made of 316 stainless steel, and with a pressure resistance range of 0~5 MPa. Its design drawing is shown below. Figure 4 As shown.

[0101] Example 2

[0102] The production method of methyl formate by low-load CO esterification using the pilot-scale apparatus of Example 1 is as follows:

[0103] 1. Check all settings on all hardware devices and control software;

[0104] 2. Open the utility unit and prepare gaseous and liquid raw materials (methanol, nitrogen, hydrogen, oxygen, argon, carbon monoxide, methyl nitrite), ensure that the pressure and liquid level are normal, and fill the reactor with 0.5 kg of shaped Pd-Cu / (SiC+Al2O3) catalyst.

[0105] 3. Turn on the analysis unit and power on all instruments, equipment, heaters, and heating tape; supply the necessary cooling water, chilled water, and instrument air for utilities; and set all manual and automatic valves to their initial values;

[0106] 4. Perform an airtightness check and begin vacuum purging;

[0107] 5. First, introduce nitrogen gas and turn on the pressurization unit and elution unit;

[0108] 6. After the pressurization unit has stabilized, introduce carbon monoxide, methyl nitrite, and hydrogen and raise the temperature to the reaction temperature. At the same time, closely monitor the parameters such as temperature, pressure, liquid level, flow rate, and composition during the reaction until the reactor temperature stabilizes at a certain value. Control the flow rate of methyl nitrite to 1.0 SLPM, the flow rate of carbon monoxide to 1.8 SLPM, the flow rate of nitrogen to 0.2 SLPM, and the flow rate of hydrogen to 0.8 SLPM.

[0109] 7. After the reactor is operating normally, start the esterification unit and introduce methanol and oxygen to allow the NO gas in the circulating gas to regenerate into methyl nitrite, the feed gas. Analyze the system and adjust the oxygen and methanol flow rates to reduce the NO content at the esterification unit outlet to below 8%. Control the methanol flow rate in the esterification tower to 0.2 kg / h, the circulating gas flow rate to 45 SLPM, the oxygen flow rate to 0.5 SLPM, the operating temperature to 50℃, and the operating pressure to 0.2 MPa. Control the reactor's operating space velocity to 2500 h⁻¹. -1 The operating temperature is 145 ℃.

[0110] 8. After the reactor is in normal operation, the content of organic matter in the circulating gas is controlled to be reduced to below 2% by the detection of the analysis unit and the adjustment of the temperature and flow rate of cold methanol.

[0111] 9. When the separation unit reaches the preset liquid level, the heating, cooling and feed valves of the corresponding tower can be opened, and the distillation tower can be started; at the same time, the composition of the bottom, inlet and outlet of each distillation tower is detected, and the quality of each product is made up to standard by adjusting the reflux ratio, the top heater and the heat tracing temperature.

[0112] 10. When the pilot plant reaches steady-state operation, on the one hand, methyl formate products can be collected gradually, and on the other hand, the process parameters of each process unit in the pilot plant can be optimized step by step. At the same time, the radial temperature distribution on the catalyst bed and the temperature distribution in different axes can be measured in the reactor, and the catalyst performance (selectivity, conversion rate, lifetime) can be investigated.

[0113] 11. Product analysis revealed a color <10, moisture content of 0.01%, evaporation residue of 3.4 mg / 100 ml, methyl formate content of 97.01%, and methanol content of 2.54%. All indicators met the national standard for superior grade products. Specific test data for the product are shown in Table 1 below.

[0114] Table 1

[0115]

[0116] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A pilot-scale system for the CO esterification to produce methyl formate, characterized in that, The CO esterification pilot-scale system for producing methyl formate includes a methyl nitrite gas pipeline, a nitrogen gas pipeline, a carbon monoxide gas pipeline, a hydrogen gas pipeline, an oxygen gas pipeline, a methanol pipeline, a circulating gas booster unit (1), an esterification tower (2), a preheater (3), a reactor (4), a hydrogen removal reactor (5), a washing tower (6), a first distillation tower (7), a dimethyl oxalate storage tank (8), a second distillation tower (9), a third distillation tower (10), a methyl formate storage tank (11), a methyl acetal storage tank (12), a methanol storage tank (13), a release unit (14), and a tail gas absorption tank (15). Among them, the methyl nitrite gas pipeline, nitrogen pipeline, carbon monoxide gas pipeline, hydrogen pipeline and circulating gas pipeline are connected to the inlet of the circulating gas boosting unit (1), the outlet of the circulating gas boosting unit (1) and the oxygen gas pipeline are connected to the inlet of the middle and lower end of the esterification tower, and the methanol pipeline is connected to the upper end of the esterification tower (2) through a liquid pump. The inlet of the preheater (3) is connected to the outlet at the top of the esterification tower (2), the inlet of the reactor (4) is connected to the outlet of the preheater (3), the inlet of the dehydrogenation reactor (5) is connected to the outlet of the reactor (4), the lower inlet of the elution tower (6) is connected to the outlet of the dehydrogenation reactor (5), and one end of the top of the elution tower (6) is directly connected to the inlet of the pressurization unit (1), and the other end is connected to the tail gas absorption tank (15) after passing through the release unit (14). The material inlet of the first distillation column (7) is connected to the bottom of the elution column (6) via a feed pump. The bottom outlet of the first distillation column (7) is connected to the dimethyl oxalate storage tank (8). The material inlet of the second distillation column (9) is connected to the top outlet of the first distillation column (7) via a feed pump. The methanol storage tank (13) is connected to the bottom outlet of the second distillation column (9) via a feed pump. The material inlet of the third distillation column (10) is connected to the top outlet of the second distillation column (9) via a feed pump. The top outlet of the third distillation column (10) is connected to the methyl formate storage tank (11). The bottom outlet of the third distillation column (10) is connected to the methyl acetal storage tank (12).

2. The pilot-scale system according to claim 1, characterized in that, The reactor (4) is a tubular reactor with a multi-section structure design; Multiple temperature control points are set at different axial heights inside the reactor (4) to monitor the temperature of each catalyst bed inside the reactor (4); The radial distribution position of the temperature sensor inside the tube of the reactor (4) is adjustable to simultaneously monitor the radial temperature distribution inside the catalyst bed; The reactor (4) is connected to the heat transfer oil system via a quick-opening flange.

3. A containerized pilot plant for the CO esterification of methyl formate, characterized in that, The pilot plant includes a container, a CO esterification pilot plant for the production of methyl formate, a utility unit, an automation control unit, and an analysis unit; The CO esterification pilot-scale system for producing methyl formate, the utility unit, the automation control unit, and the analysis unit are all housed inside the container. The CO esterification pilot-scale system for producing methyl formate is selected from the pilot-scale system described in claim 1 or 2.

4. The pilot-scale apparatus according to claim 3, characterized in that, The utility unit includes a heating circulation system, a cooling water circulation system, a chilled water circulation system, a vacuum pump, and an air compressor; The heating circulation system is connected to the preheater (3), reactor (4), first distillation column (7), second distillation column (9), and third distillation column (10) via pipelines; the cooling water circulation system is connected to the compressor unit and the heat transfer oil system; the chilled water circulation system is connected to the esterification column (2), the elution column, and the methyl formate storage tank (11); and the vacuum pump is connected to the esterification column (2), reactor (4), and elution column (6).

5. The pilot-scale apparatus according to claim 3, characterized in that, The automated control unit includes a detection unit, a control unit, and an execution unit; The detection unit includes a remote pressure sensor, a remote liquid level sensor, and a remote temperature sensor; the control unit adopts a distributed control system; and the execution unit includes pneumatic and electric switching valves and electric heat tracing.

6. The pilot-scale apparatus according to claim 3, characterized in that, The analytical unit includes an online gas chromatograph, an online mass spectrometer, and a nitrogen oxide analyzer.

7. The pilot-scale apparatus according to claim 4, characterized in that, The inlet and outlet of the esterification tower (2), the inlet and outlet of the reactor (4), and the top of the elution tower (6) are all connected to the analysis unit for real-time online analysis.

8. The pilot-scale apparatus according to claim 4, characterized in that, Manual sampling ports are provided at the top and bottom of the first distillation column (7) and the second distillation column (9).

9. A method for producing methyl formate by CO esterification, characterized in that, The production method employs the pilot-scale system described in either claim 1 or 2; Includes the following steps: The circulating gas, methyl nitrite, nitrogen, carbon monoxide and hydrogen enter the circulating gas pressurization unit (1) and are pressurized. The pressurized mixed gas and oxygen enter the middle and lower end of the esterification tower (2). Then methanol enters the upper end of the esterification tower (2) through a fluid pump and reacts with the mixed gas in the esterification tower (2) to generate methyl nitrite. The gas effluent from the top of the esterification tower (2) enters the preheater (3) for preheating. The preheated gas enters the reactor (4) and reacts with the catalyst. The effluent from the bottom of the reactor (4) enters the dehydrogenation reactor (5) for dehydrogenation, and then enters the elution tower (6) for separation. It is absorbed by cold methanol. The liquid product enters the first distillation tower (7) for gas-liquid separation by a liquid pump. The top product of the first distillation tower (7) enters the second distillation tower (9). The bottom product of the first distillation tower (7) enters the dimethyl oxalate storage tank (8). The top product of the second distillation tower (9) enters the third distillation tower (10). The bottom product of the second distillation tower (9) enters the methanol storage tank (13). The top product of the third distillation tower (10) enters the methyl formate storage tank (11). The bottom product of the third distillation tower enters the methyl acetal storage tank (12).

10. The production method according to claim 9, characterized in that, The operating parameters of the circulating gas booster unit (1) are as follows: methyl nitrite flow rate 0~16 SLPM, carbon monoxide flow rate 0~25 SLPM; nitrogen flow rate 0~30 SLPM; hydrogen flow rate 0~8 SLPM, and the design pressure is 1 MPa; The operating parameters of the esterification tower (2) are as follows: methanol flow rate 0~1.68 Kg / h, circulating gas flow rate 0~80 SLPM, oxygen flow rate 0~4 SLPM, design working temperature 0~200 ℃, and working pressure 0~1 Mpa; The operating parameters of reactor (4) are as follows: operating space velocity is 0~5000 h⁻¹ -1 The maximum design temperature is 200℃; The operating parameters of the first distillation column (7), the second distillation column (9), and the third distillation column (10) are as follows: height-to-diameter ratio of 26~65:1, operating temperature of 0~200 ℃, and design pressure of 0.4 MPa.

11. A complete production method for methyl formate by CO esterification, characterized in that, The full-process production method uses the pilot-scale device described in any one of claims 3 to 8; Includes the following steps: S1. Check all settings on all hardware devices and control software; S2. Start the utility unit, prepare gas and liquid raw materials, ensure that the pressure and liquid level on each storage tank are normal, and fill the reactor with catalyst; S3. Turn on the analysis unit and power on all instruments, pumps, heaters, and heat tracing equipment; supply the necessary cooling water, chilled water, heat transfer oil, and instrument air for the utilities; and set all manual and automatic valves to their initial values. S4. Check for airtightness and begin vacuum purging; S5. First, introduce nitrogen gas and turn on the circulating gas pressurization unit (1) and the washing tower (6). S6. After the circulating gas booster unit (1) is running stably, carbon monoxide, methyl nitrite and hydrogen are introduced and the temperature is raised to the reaction temperature. At the same time, the process parameters consisting of temperature, pressure, liquid level and flow rate of each process unit in the system are monitored until the reactor (4) is running normally. S7. After the reactor (4) is operating normally, turn on the esterification tower (2) to regenerate the nitric oxide in the circulating gas into the raw material gas methyl nitrite. S8. When the washing tower (6) reaches the preset liquid level, the first distillation tower (7), the second distillation tower (9), and the third distillation tower (10) are turned on, and the heating and feeding of the corresponding towers are turned on to make the distillation towers operate stably. S9. When the pilot plant reaches steady-state operation, on the one hand, methyl formate products are gradually collected, and on the other hand, the process parameters of each process unit in the pilot plant are gradually collected and optimized.

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