Production process and system for co-production of dimethyl oxalate and dimethyl carbonate

Abstract

The invention relates to the technical field of novel chemical processes, and discloses a production process and system for co-production of dimethyl oxalate and dimethyl carbonate. According to the co-production process, the characteristic that the top of a nitric oxide / methanol / nitric acid redox tower is rich in methyl nitrite in a dimethyl oxalate synthesis process is ingeniously utilized, and the raw material ratio requirement of the chlorine-free dimethyl carbonate synthesis catalyst can be well met for dimethyl carbonate production only by simply purifying and adjusting the nitrogen oxide / methanol / nitric acid redox tower. The co-production process is simple in flow and low in capital investment, the product structure can be adjusted in time, and economic benefits are increased.

Description

Technical Field

[0001] The patent of this invention relates to the field of new chemical process technology, and specifically to a production process and system for co-producing dimethyl oxalate and dimethyl carbonate. Background Art

[0002] At present, the gas phase carbonyl production process of synthesizing dimethyl oxalate DMO from carbon monoxide CO and methyl nitrite MN is mature and has been applied on a large scale. In addition, the new process of synthesizing dimethyl carbonate DMC from CO and MN carbonyl also has certain economic advantages in China. The process currently mainly uses chlorine-containing precious metal catalysts, and a certain amount of hydrogen chloride concentration needs to be maintained in the reaction cycle gas. However, hydrogen chloride cannot be introduced into the dimethyl oxalate synthesis system, so it is difficult to achieve the co-production of dimethyl carbonate in the existing dimethyl oxalate device.

[0003] The successful development of the chlorine-free dimethyl carbonate synthesis catalyst makes it unnecessary to introduce hydrogen chloride into the reaction system, thus making it possible to couple with the existing dimethyl oxalate synthesis process. In the synthesis of dimethyl carbonate, since the active center of the catalyst is +2-valent Pd, it is easily reduced by CO in the raw gas and causes the catalyst to be deactivated. In order to maintain the +2-valent state of Pd in ​​the catalyst, the raw gas requires a high MN concentration and a low CO concentration, and generally requires a molar ratio of MN to CO of 3 to 7:1; the active center of the dimethyl oxalate synthesis catalyst is 0-valent Pd, and its requirement for the molar ratio of CO to MN in the raw gas is just the opposite, requiring a high CO concentration and a relatively low MN concentration, generally a molar ratio of CO to MN of 1.5 to 3:1, which makes it difficult for the methyl nitrite esterification regeneration system synthesized from dimethyl oxalate to synchronously adjust the raw gas composition of the two products.

[0004] We have made a detailed introduction to the existing gas phase carbonyl synthesis process of dimethyl oxalate in patent CN101544539, in which the tail gas separated from the dimethyl oxalate produced in the carbonylation reactor is recycled to generate methyl nitrite and CO through an esterification regeneration tower. At the same time, the gas phase carbonyl synthesis process of dimethyl carbonate is similar to the dimethyl oxalate process, mainly in that the CO and methyl nitrite raw gas pass through the carbonylation reaction synthesizer, the liquid product is collected and purified to obtain dimethyl carbonate, and the gas product is circulated or emptied to realize the entire process.

[0005] Today's coal chemical market is changing rapidly. How to quickly build a dimethyl carbonate production process with minimal investment cost is of great importance to improving the market competitiveness of existing dimethyl oxalate production enterprises. Therefore, it is urgent to develop a process for co-producing dimethyl carbonate with dimethyl oxalate. Summary of the invention

[0006] The object of the present invention is to provide a production process and system for co-producing dimethyl carbonate from dimethyl oxalate, which can realize the sharing of raw gas system and circulating gas in the production process of dimethyl carbonate and the production process of dimethyl oxalate, and realize the joint production of dimethyl carbonate and dimethyl oxalate.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] Provided is a production process for co-producing dimethyl carbonate from dimethyl oxalate. A chlorine-free dimethyl carbonate catalyst is used in the dimethyl carbonate production process, which is a chlorine-free dimethyl carbonate production process. A methyl nitrite esterification regeneration tower is used in the dimethyl oxalate production process for methyl nitrite regeneration, a methyl nitrite raw material is provided, a nitric oxide / methanol / nitric acid oxidation-reduction tower synthesizes methyl nitrite by adding nitric acid, which is used for methyl nitrite supplementation, and the circulating gas in the dimethyl oxalate production process is returned to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling.

[0009] A top gas from the nitric oxide / methanol / nitric acid redox tower in the dimethyl oxalate production process is used as raw gas for dimethyl carbonate synthesis. After being washed and purified and adjusting the molar ratio of CO to MN in the raw gas to a target ratio, dimethyl carbonate is synthesized through the dimethyl carbonate production process. The circulating gas generated by the dimethyl carbonate synthesis is returned to the esterification regeneration tower and the nitric oxide / methanol / nitric acid redox tower in the dimethyl oxalate production process for recycling.

[0010] According to the above scheme, the molar ratio of CO to MN in the raw gas for producing dimethyl carbonate is 1:3 to 1:7.

[0011] According to the above scheme, the volume content of methyl nitrite in the methyl nitrite-rich top gas drawn out from the top of the nitric oxide / methanol / nitric acid redox tower is 18-30%.

[0012] According to the above scheme, the volume content of CO in the methyl nitrite-rich top gas drawn out from the top of the nitric oxide / methanol / nitric acid redox tower is 7-22%.

[0013] According to the above scheme, the combined production process of dimethyl oxalate and dimethyl carbonate includes a production process of dimethyl oxalate DMO and a production process of dimethyl carbonate DMC.

[0014] In the dimethyl oxalate production process, the MN raw gas washed with methanol produced in the methyl nitrite esterification regeneration tower is preheated / heated to increase the temperature, and then enters the CO and MN mixer, and CO is added to adjust the molar ratio of CO and MN in the raw gas to reach the target ratio required for the production of dimethyl oxalate, and the CO and MN mixed gas reaching the target ratio is sent to the DMO carbonylation reactor, and the catalytic carbonylation reaction is carried out under the DMO carbonylation catalyst, and then the mixed gas enters the DMO absorption tower after the catalytic carbonylation reaction, and the gas phase outlet gas of the DMO absorption tower is sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower, and the liquid phase outlet of the DMO absorption tower collects dimethyl oxalate;

[0015] In the dimethyl carbonate production process, a gas rich in methyl nitrite is drawn out from the top of a nitric oxide / methanol / nitric acid redox tower, washed with methanol, preheated / heated and heated, and then used as a raw gas for dimethyl carbonate production to enter a CO and MN mixer, the molar ratio of CO and MN in the raw gas is adjusted to reach a target ratio required for dimethyl carbonate production, and the mixed gas of CO and MN reaching the target ratio is sent to a DMC carbonylation reactor, where a catalytic carbonylation reaction is carried out under the catalysis of a chlorine-free dimethyl carbonate carbonylation catalyst, and then the mixed gas enters a DMC absorption tower after the catalytic carbonylation reaction, and the gas phase outlet gas of the DMC absorption tower is sent to a methyl nitrite esterification regeneration tower and a nitric oxide / methanol / nitric acid redox tower in the dimethyl oxalate production process, and dimethyl carbonate DMC is collected at the liquid phase outlet of the DMC absorption tower.

[0016] According to the above scheme, the gas phase outlet gas of the DMO absorption tower and the gas phase outlet gas of the DMC absorption tower are combined into a circulating raw gas, and the combined circulating raw gas is further divided into two raw gas streams, of which the majority stream, generally accounting for 70-90% of the total gas volume, directly enters the inlet of the methyl nitrite esterification regeneration tower; the other stream of raw gas, generally accounting for 10-30% of the total gas volume, can be adjusted by setting a valve or adding a compressor to increase the pressure and enter the inlet of the nitric oxide / methanol / nitric acid oxidation-reduction tower. Specifically, the gas phase outlet gas of the DMO absorption tower is connected to the inlet of the methyl nitrite esterification regeneration tower and the oxidation-reduction tower through the first circulation compressor; the gas phase outlet of the DMC absorption tower is sent to the inlet of the methyl nitrite esterification regeneration tower and the oxidation-reduction tower through the second circulation compressor, and the first circulation compressor and the second circulation compressor are shared, that is, the gas phase outlet of the DMC absorption tower is connected to the inlet of the methyl nitrite esterification regeneration tower and the oxidation-reduction tower through the first circulation compressor in the DMO synthesis system, that is, the outlet gas phase of the DMC absorption tower is directly connected to the inlet of the circulation compressor in the DMO synthesis system.

[0017] According to the above scheme, the liquid phase outlet of the nitric oxide / methanol / nitric acid redox tower is connected to the inlet of the methanol recovery tower for recovering methanol.

[0018] According to the above scheme, the liquid phase in the methyl nitrite esterification regeneration tower directly enters the nitric oxide / methanol / nitric acid oxidation-reduction tower, and the liquid phase in the nitric oxide / methanol / nitric acid oxidation-reduction tower directly enters the methanol absorption tower, that is, the liquid phases in the two towers are finally mixed together and enter the methanol recovery tower to recover methanol.

[0019] According to the above scheme, in the production of dimethyl oxalate, the outlet gas of the methyl nitrite esterification regeneration tower and the outlet gas of the DMO carbonylation reactor are preheated and heated by heat exchange, and then sent to the DMO carbonylation reactor for reaction. The outlet gas of the DMO carbonylation reactor enters the DMO absorption tower after heat exchange;

[0020] In the production of dimethyl carbonate, the methyl nitrite-rich top gas drawn out from the nitric oxide / methanol / nitric acid redox tower and the outlet gas of the DMC carbonylation reactor are preheated and heated by heat exchange, and then sent to the DMC carbonylation reactor for reaction. The outlet gas of the DMC carbonylation reactor enters the DMC absorption tower after heat exchange.

[0021] According to the above scheme, the DMC carbonylation reactor is a shell-and-tube reactor, in which the chlorine-free dimethyl carbonate catalyst is loaded, and the shell-and-tube reactor adopts hot water circulation to transfer heat and produces low-pressure steam for preheating / heating. The reaction pressure is 0.3-0.5MPa, and the gas space velocity is 3000-8000h -1 .

[0022] According to the above scheme, the overhead gas from the nitric oxide / methanol / nitric acid redox tower is passed through a methanol washing purification tower to remove water and acid content in the raw gas to less than 100×10 -6 (V / V).

[0023] According to the above scheme, the reaction temperature of the DMO carbonylation reactor is 100-130°C; the reaction temperature of the DMC carbonylation reactor is 100-130°C.

[0024] According to the above scheme, the chlorine-free dimethyl carbonate catalyst used in the DMC carbonylation reactor can be selected from, but not limited to, the chlorine-free dimethyl carbonate catalyst disclosed in patent CN116899614A, wherein the chlorine-free dimethyl carbonate catalyst comprises an active component Pd and a molecular sieve carrier, and the molecular sieve carrier is also loaded with structural stabilizing additives Cu, K and metal M; in the catalyst, by mass percentage, Pd is 0.25-2%, Cu is 0.05-10%, K is 0.01-5%, and M is 0.01-1%. Other chlorine-free dimethyl carbonate catalysts are also acceptable. Different chlorine-free dimethyl carbonate catalysts have different activities, and the molar ratio requirements of MN and CO are slightly different, but they can all be used for the co-production of dimethyl oxalate and dimethyl carbonate of the present invention.

[0025] According to the above scheme, the particle size of the chlorine-free dimethyl carbonate catalyst is Φ(3-6)×(3-6)mm.

[0026] According to the above scheme, the DMC absorption tower is a methanol absorption tower, and the gas at the outlet of the DMC carbonylation reactor enters the methanol absorption tower after heat exchange and cooling by a cooler, and the DMC product is absorbed by methanol.

[0027] According to the above scheme, the DMO absorption tower is a methanol absorption tower. The gas at the outlet of the DMO carbonylation reactor enters the methanol absorption tower after heat exchange and cooling in a cooler, and the DMO product is absorbed by methanol.

[0028] According to the above scheme, the liquid phase outlet of the DMC absorption tower is sent to the liquid phase separation system for dimethyl carbonate refining. The liquid phase separation system can use devices such as pressure swing distillation and melt crystallization devices, generally including a light-weight removal tower, a pressure tower and a refining tower. The outlet of the DMC absorption tower is connected to the inlet of the light-weight removal tower, the outlet of the light-weight removal tower is connected to the inlet of the pressure tower, the outlet of the pressure tower is connected to the inlet of the refining tower, the outlet of the refining tower is connected to the inlet of the melt crystallization device, and the outlet of the melt crystallization device outputs the DMC product.

[0029] According to the above scheme, the melt crystallization device includes a first melt crystallizer and a second melt crystallizer of DMC with different purities arranged in parallel. A flow regulating valve is provided at the outlet of the refining tower to connect the inlets of the first melt crystallizer and the second melt crystallizer of DMC respectively. The outlet of the melt crystallizer is connected to a drying device.

[0030] According to the above scheme, the liquid phase outlet of the DMO absorption tower is sent to the liquid phase separation system for refining dimethyl oxalate. The liquid phase separation system generally includes a light-heavy removal tower, a pressurizing tower and a refining tower. The liquid phase outlet of the DMO absorption tower is connected to the inlet of the first light-heavy removal tower, the outlet of the first light-heavy removal tower is connected to the inlet of the pressurizing tower, and the outlet of the pressurizing tower is connected to the inlet of the first refining tower.

[0031] The second aspect of the present invention provides a production system for the above-mentioned production process of dimethyl oxalate and dimethyl carbonate, wherein the production system comprises a DMO synthesis system and a DMC synthesis system.

[0032] The DMO synthesis system includes a methyl nitrite esterification regeneration tower, a nitric oxide / methanol / nitric acid oxidation-reduction tower, a first heater, a first CO and MN mixer, a DMO carbonylation reactor, a circulation compressor, a DMO absorption tower, and a first liquid phase separation system.

[0033] The top outlet of the methyl nitrite esterification regeneration tower is connected to the inlet of the first heater, the outlet of the first heater is connected to the inlet of the first CO and MN mixer, the outlet of the first CO and MN mixer is connected to the inlet of the DMO carbonylation reactor, the outlet gas of the DMO carbonylation reactor is connected to the inlet of the DMO absorption tower after heat exchange cooling, the gas phase outlet of the DMO absorption tower is connected to the inlet of the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower through a circulating compressor, and the liquid phase outlet of the DMO absorption tower is connected to the first liquid phase separation system for refining dimethyl oxalate;

[0034] The DMC synthesis system includes a methanol washing and purification tower, a second heater, a second CO and MN mixer, a DMC carbonylation reactor, a circulating compressor, a DMC absorption tower, and a second liquid phase separation system.

[0035] The outlet of the nitric oxide / methanol / nitric acid redox tower of the DMO synthesis system is connected to the inlet of the methanol washing and purification tower, the gas phase outlet of the methanol washing and purification tower is connected to the inlet of the second heater, the outlet of the second heater is connected to the inlet of the second CO and MN mixer, the outlet of the second CO and MN mixer is connected to the inlet of the DMC carbonylation reactor, the outlet gas of the DMC carbonylation reactor is cooled by heat exchange and enters the DMC absorption tower, and the gas phase outlet of the DMC absorption tower is connected to the inlet of the methyl nitrite regeneration tower and the inlet of the nitric oxide / methanol / nitric acid redox tower through a circulating compressor. The compressor can utilize the circulating gas compressor of the DMO synthesis system, and the circulating compressor of the DMO synthesis system and the DMC synthesis system is shared, that is, the outlet gas phase of the DMC absorption tower is directly connected to the inlet of the circulating gas compressor of the DMO synthesis system. The liquid phase outlet of the DMC absorption tower is connected to the second liquid phase separation system for the refining of dimethyl carbonate.

[0036] According to the above scheme, the DMO synthesis system also includes a first heat exchanger, the cold end inlet of the first heat exchanger is connected to the outlet of the methyl nitrite esterification regeneration tower, the cold end outlet is connected to the inlet of the first CO and MN mixer, the hot end inlet of the first heat exchanger is connected to the gas phase outlet of the DMO carbonylation reactor, and the hot end outlet of the first heat exchanger is connected to the DMO absorption tower. The outlet gas of the methyl nitrite esterification regeneration tower and the outlet gas of the DMO carbonylation reactor are preheated and heated by heat exchange and temperature increase, and then sent to the DMO carbonylation reactor for reaction;

[0037] The DMC synthesis system also includes a second heat exchanger, the cold end inlet of the second heat exchanger is connected to the outlet of the methanol washing and purification tower, the cold end outlet is connected to the inlet of the second CO and MN mixer, the hot end inlet of the second heat exchanger is connected to the gas phase outlet of the DMC carbonylation reactor, and the hot end outlet of the second heat exchanger is connected to the DMC absorption tower. The top gas rich in methyl nitrite drawn out of the nitric oxide / methanol / nitric acid oxidation-reduction tower and the outlet gas of the DMC carbonylation reactor are preheated and heated by heat exchange and sent to the DMC carbonylation reactor for reaction.

[0038] According to the above scheme, the above production system also includes a methanol recovery tower, and the liquid phase outlet of the nitric oxide / methanol / nitric acid redox tower is connected to the inlet of the methanol recovery tower for recovering methanol.

[0039] Furthermore, the liquid phase outlet in the methyl nitrite esterification regeneration tower is connected to the liquid phase inlet of the nitric oxide / methanol / nitric acid redox tower, directly enters the nitric oxide / methanol / nitric acid redox tower, merges with the liquid phase in the nitric oxide / methanol / nitric acid redox tower, and then enters the methanol absorption tower, that is, the liquid phases in the two towers are finally mixed together and enter the methanol recovery tower to recover methanol.

[0040] According to the above scheme, the first liquid phase separation system generally includes a light-heavy degassing tower, a first pressurizing tower and a first refining tower. The liquid phase outlet of the DMO absorption tower is connected to the inlet of the first light-heavy degassing tower, the outlet of the first light-heavy degassing tower is connected to the inlet of the first pressurizing tower, and the outlet of the pressurizing tower is connected to the inlet of the first refining tower.

[0041] According to the above scheme, the second liquid phase separation system comprises a second light-weight-removal tower, a second pressurizing tower, a second refining tower and a melt crystallization device. The liquid phase outlet of the DMC absorption tower is connected to the inlet of the second light-weight-removal tower, the outlet of the second light-weight-removal tower is connected to the inlet of the second refining tower, and the inlet of the second refining tower is connected to the melt crystallization device.

[0042] In the nitric oxide / methanol / nitric acid redox tower, nitric acid is added to supplement the nitrogen oxides consumed in the circulating raw gas entering the tower, and methyl nitrite is prepared by the reaction of nitric oxide, methanol and nitric acid to supplement methyl nitrite. The top gas of the nitric oxide / methanol / nitric acid redox tower has fully converted NO into MN by adding nitric acid, and the MN concentration in its gas phase is the highest in the circulation system. Moreover, since it is a gas after the synthesis reaction, its CO concentration is the lowest in the circulation system, which can well meet the requirements of the chlorine-free dimethyl carbonate synthesis process. The tower top gas drawn out from the nitrogen monoxide / methanol / nitric acid redox tower is used as the raw gas for dimethyl carbonate synthesis, and the characteristic that the tower top gas of the redox tower is rich in methyl nitrite in the dimethyl oxalate synthesis is cleverly utilized. The raw material ratio requirement of the chlorine-free dimethyl carbonate synthesis catalyst can be well met after simple purification. The process flow is simple, and the investment is saved. Based on the existing dimethyl oxalate synthesis device, it is easy to realize the co-production of dimethyl carbonate, adjust the product structure, and increase the economic benefit. The circulating gas generated by the dimethyl carbonate synthesis can be shared with the circulating gas of the dimethyl oxalate production process.

[0043] The invention is based on a chlorine-free gas phase carbonylation process for synthesizing dimethyl carbonate. Technically, through an ingenious and reasonable design concept, the raw material gas of dimethyl oxalate in the existing relatively mature process is directly drained and processed during the recycling process to meet the conditions for producing dimethyl carbonate, thereby realizing that the production process of dimethyl carbonate DMC can be directly grafted onto the process of dimethyl oxalate DMO in the existing mature technology, that is, most of the devices and equipment can be shared with the dimethyl oxalate process, and the co-production of dimethyl carbonate and dimethyl oxalate can be easily achieved by adding a few sets of devices and equipment in small quantities, thereby greatly reducing the investment cost and improving the production efficiency of the factory.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] The process of the invention can realize the common use of the raw gas system and the circulating gas in the dimethyl carbonate production process and the dimethyl oxalate production process, thereby realizing the joint production of dimethyl carbonate and dimethyl oxalate.

[0046] The raw gas system and circulating gas compression device in the dimethyl carbonate production process are used in conjunction with the dimethyl oxalate production process, which greatly saves equipment investment, significantly reduces floor space, improves material recycling efficiency, reduces energy consumption, and can adjust product structure to increase economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a schematic flow chart of the process for producing dimethyl oxalate and dimethyl carbonate provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the embodiments to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. For ordinary technicians in this technical field, as long as the various changes are within the scope of the attached claims, all inventions or utility models created by the concept of the present invention are protected.

[0049] A production system of dimethyl oxalate and dimethyl carbonate, such as Figure 1 As shown, it includes DMO synthesis system and DMC synthesis system.

[0050] The DMO synthesis system includes a methyl nitrite esterification regeneration tower, a nitric oxide / methanol / nitric acid oxidation-reduction tower, a first heater, a first CO and MN mixer, a DMO carbonylation reactor, a circulating compressor, a DMO absorption tower, and a first liquid phase separation system. Further, the first liquid phase separation system includes a light-heavy removal tower, a first pressurizing tower, and a first refining tower, the liquid phase outlet of the DMO absorption tower is connected to the inlet of the first light-heavy removal tower, the outlet of the first light-heavy removal tower is connected to the inlet of the first pressurizing tower, and the outlet of the pressurizing tower is connected to the inlet of the first refining tower;

[0051] The top outlet of the methyl nitrite esterification regeneration tower is connected to the inlet of the first heater, the outlet of the first heater is connected to the inlet of the first CO and MN mixer, the outlet of the first CO and MN mixer is connected to the inlet of the DMO carbonylation reactor, the outlet gas of the DMO carbonylation reactor is connected to the inlet of the DMO absorption tower after heat exchange cooling, the gas phase outlet of the DMO absorption tower is connected to the inlet of the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid redox tower through a circulating compressor, the liquid phase outlet of the DMO absorption tower is connected to the first liquid phase separation system for refining dimethyl oxalate, specifically, the liquid phase outlet of the DMO absorption tower is connected to the inlet of the first light and heavy removal tower, and the outlet of the first light and heavy removal tower is connected to the inlet of the first refining tower.

[0052] In the dimethyl oxalate production process, the MN raw gas washed with methanol produced in the methyl nitrite esterification regeneration tower is preheated / heated to increase the temperature, and then enters the CO and MN mixer, and CO is added to adjust the molar ratio of CO and MN in the raw gas to reach the target ratio required for the production of dimethyl oxalate, and the CO and MN mixed gas reaching the target ratio is sent to the DMO carbonylation reactor, and the catalytic carbonylation reaction is carried out under the DMO carbonylation catalyst, and then the mixed gas enters the DMO absorption tower after the catalytic carbonylation reaction, and the gas phase outlet gas of the DMO absorption tower is sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower, and the liquid phase outlet of the DMO absorption tower collects dimethyl oxalate;

[0053] The DMC synthesis system includes a methanol washing and purification tower, a second heater, a second CO and MN mixer, a DMC carbonylation reactor, a circulating compressor, a DMC absorption tower, and a second liquid phase separation system. Further, the second liquid phase separation system includes a light-heavy removal tower, a pressurizing tower, and a refining tower, the outlet of the DMC absorption tower is connected to the inlet of the light-heavy removal tower, the outlet of the light-heavy removal tower is connected to the inlet of the pressurizing tower, the outlet of the pressurizing tower is connected to the inlet of the refining tower, the outlet of the refining tower is connected to the inlet of the melt crystallization device, and the outlet of the melt crystallization device outputs the DMC product.

[0054] The outlet of the nitric oxide / methanol / nitric acid oxidation-reduction tower of the DMO synthesis system is connected to the inlet of the methanol washing and purification tower, the gas phase outlet of the methanol washing and purification tower is connected to the inlet of the second heater, the outlet of the second heater is connected to the inlet of the second CO and MN mixer, the outlet of the second CO and MN mixer is connected to the inlet of the DMC carbonylation reactor, the outlet gas of the DMC carbonylation reactor enters the DMC absorption tower after heat exchange cooling, and the gas phase outlet of the DMC absorption tower is connected to the inlet of the methyl nitrite esterification regeneration tower and the inlet of the nitric oxide / methanol / nitric acid oxidation-reduction tower through a circulating compressor. The compressor can use the circulating gas compressor of the DMO synthesis system, and the circulating compressor of the DMO synthesis system and the DMC synthesis system is shared, that is, the outlet gas phase of the DMC absorption tower is directly connected to the inlet of the circulating gas compressor of the DMO synthesis system, and the liquid phase outlet of the DMC absorption tower is connected to the second liquid phase separation system for refining dimethyl carbonate, specifically, the liquid phase outlet of the DMC absorption tower is connected to the inlet of the second light and heavy tower, the outlet of the second light and heavy tower is connected to the inlet of the second refining tower, and the inlet of the second refining tower is connected to the melting crystallization device.

[0055] In the dimethyl carbonate production process, a gas rich in methyl nitrite is drawn out from the top of a nitric oxide / methanol / nitric acid redox tower, washed with methanol, preheated / heated and heated, and then used as a raw gas for dimethyl carbonate production to enter a CO and MN mixer, the molar ratio of CO and MN in the raw gas is adjusted to reach a target ratio required for dimethyl carbonate production, and the mixed gas of CO and MN reaching the target ratio is sent to a DMC carbonylation reactor, where a catalytic carbonylation reaction is carried out under the catalysis of a chlorine-free dimethyl carbonate carbonylation catalyst, and then the mixed gas enters a DMC absorption tower after the catalytic carbonylation reaction, and the gas phase outlet gas of the DMC absorption tower is sent to a methyl nitrite esterification regeneration tower and a nitric oxide / methanol / nitric acid redox tower in the dimethyl oxalate production process, and dimethyl carbonate DMC is collected at the liquid phase outlet of the DMC absorption tower.

[0056] Furthermore, the DMO synthesis system further comprises a first heat exchanger, wherein the cold end inlet of the first heat exchanger is connected to the outlet of the methyl nitrite esterification regeneration tower, the cold end outlet is connected to the inlet of the first CO and MN mixer, the hot end inlet of the first heat exchanger is connected to the gas phase outlet of the DMO carbonylation reactor, and the hot end outlet of the first heat exchanger is connected to the DMO absorption tower, and the outlet gas of the methyl nitrite esterification regeneration tower and the outlet gas of the DMO carbonylation reactor are preheated and heated by heat exchange and temperature raising, and then sent to the DMO carbonylation reactor for reaction;

[0057] The DMC synthesis system also includes a second heat exchanger, the cold end inlet of the second heat exchanger is connected to the outlet of the methanol washing and purification tower, the cold end outlet is connected to the inlet of the second CO and MN mixer, the hot end inlet of the second heat exchanger is connected to the gas phase outlet of the DMC carbonylation reactor, and the hot end outlet of the second heat exchanger is connected to the DMC absorption tower. The top gas rich in methyl nitrite drawn out of the nitric oxide / methanol / nitric acid oxidation-reduction tower and the outlet gas of the DMC carbonylation reactor are preheated and heated by heat exchange and sent to the DMC carbonylation reactor for reaction.

[0058] Furthermore, the above-mentioned production system also includes a methanol recovery tower for recovering methanol. The liquid phase outlet in the methyl nitrite esterification regeneration tower is connected to the liquid phase inlet of the nitric oxide / methanol / nitric acid redox tower, directly enters the nitric oxide / methanol / nitric acid redox tower, and then merges with the liquid phase in the nitric oxide / methanol / nitric acid redox tower and enters the methanol absorption tower, that is, the liquid phases in the two towers are finally mixed together and enter the methanol recovery tower to recover methanol.

[0059] Specifically, the raw gas at the inlet of the dimethyl oxalate synthesis reactor is composed of 15-32% CO, 10-16% MN, 2-10% NO, and the rest are inert components such as CH3OH, N2O, CO2, CH4, N2, etc. that do not participate in the reaction. The concentrations of CO and MN at the outlet of the reactor are reduced, and the concentration of NO is increased; the gas after the reaction is absorbed and compressed by DMO and then enters the esterification regeneration tower and the redox tower; the gas is drawn out from the gas phase outlet of the redox tower of the dimethyl oxalate production system and enters the DMC synthesis system, wherein the key components are 7-22% CO, 18-30% MN, 1-5% NO, and the rest are CH3OH, N2O, CO2, CH4, N2, etc. The gas rich in methyl nitrite is used as a raw material, and then the water and acid content in the raw gas is removed to less than 100×10 -6 (V / V), and then adjust the molar ratio of CO to MN in the raw gas to 1:3-1:7 by adding a small amount of CO or not adding any CO as needed, and mix them fully and evenly in the CO and MN mixer.

[0060] Then preheat / heat to 100-130°C, and then enter the shell-and-tube dimethyl carbonate synthesis reactor, the shell-and-tube is filled with NaY molecular sieve loaded Pd-Cu as catalyst, the catalyst particle size is Φ(3-6)×(3-6)mm, hot water circulation is used outside the shell-and-tube to transfer heat and produce low-pressure steam as a by-product, the reaction pressure is 0.3-0.5MPa, and the gas space velocity is 3000-8000h -1 After sufficient catalytic reaction, the gas at the outlet of the dimethyl carbonate synthesis reactor is cooled by heat exchange and cooler and then enters the product absorption tower, where the dimethyl carbonate product is absorbed by methanol. The gas phase is pressurized by the compressor and then returns to the esterification regeneration tower and oxidation-reduction tower for dimethyl oxalate synthesis, thus realizing a closed-loop cycle, reducing material loss and increasing product yield.

[0061] Finally, the absorption liquid in the DMC absorption tower enters the liquid phase separation system, which adopts the separation method of pressure swing distillation. The pressure swing distillation tower is equipped with a light and heavy removal tower, a pressure tower, and a refining tower. Among them, the top operating pressure of the light and heavy removal tower is 0-100KPaG, and the operating temperature is 20-180℃; the top operating pressure of the pressure tower is 0.2-2MPaG, and the operating temperature is 20-200℃; the top operating pressure of the refining tower is 0-80KPaG, and the operating temperature is 15-160℃; the refining tower produces 99.1-99.5% dimethyl carbonate products.

[0062] To further improve product quality, the outlet of the refining tower is also connected to a melt crystallization device. The 99.1-99.5% dimethyl carbonate product extracted from the refining tower is sent to the melt crystallization device, which is equipped with premium and high-purity melt crystallizers to ensure high-quality products of different specifications. After the melt crystallization system, a dimethyl carbonate product of ≥99.99% can be obtained to meet the needs of the high-end market.

[0063] The specific implementation cases are as follows:

[0064] Example 1

[0065] The water and acid content in the raw gas MN is less than 100×10 -6 (V / V); MN volume content is 27%; in the CO and MN mixer, the molar ratio of CO to MN is 1:3; the preheating / heater temperature is 110°C; the shell-and-tube dimethyl carbonate synthesis reactor has a reaction pressure of 0.3MPa and a gas space velocity of 5000h -1 After the raw gas is fully reacted with Pd-Cu-KV as a catalyst (0.4% Pd·7.2% Cu·0.8% K·2.4% V·89.2% mixed molecular sieve, mixed molecular sieve ZSM-35 molecular sieve and 0.5g Naβ molecular sieve by mass percentage), the space-time yield of DMC is 273g / L*h.

[0066] The absorption liquid in the DMC absorption tower has an operating pressure of 80KPaG and an operating temperature of 80℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 0.6MPaG and the operating temperature is 110℃; the operating pressure of the top of the refining tower is 80KPaG and the operating temperature is 130℃; the product of 97.9% dimethyl carbonate produced by the refining tower. The gas phase outlet gas of the DMC absorption tower is divided into two streams through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, so as to produce dimethyl oxalate and dimethyl carbonate.

[0067] Example 2

[0068] The water and acid content in the raw gas MN is less than 100×10 -6 (V / V); MN volume content is 18%; in the CO and MN mixer, the molar ratio of CO to MN is 1:3; the preheating / heater temperature is 100°C; the shell-and-tube dimethyl carbonate synthesis reactor has a reaction pressure of 0.3MPa and a gas space velocity of 3000h -1 After the raw gas is fully reacted with NaY molecular sieve-loaded Pd-Cu-KV as a catalyst (0.4% Pd·7.2% Cu·0.8% K·2.4% V·89.2% mixed molecular sieve, mixed molecular sieve ZSM-35 molecular sieve and 0.5g Naβ molecular sieve by mass percentage), the space-time yield of DMC is 135g / L*h.

[0069] The absorption liquid in the DMC absorption tower has an operating pressure of 70KPaG and an operating temperature of 110℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 0.5MPaG and the operating temperature is 100℃; the operating pressure of the top of the refining tower is 60KPaG and the operating temperature is 80℃; the 97.4% dimethyl carbonate product extracted from the refining tower. The gaseous outlet gas of the DMC absorption tower is divided into two gases through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, and the co-production of dimethyl oxalate and dimethyl carbonate is carried out. The gaseous outlet gas of the DMC absorption tower is divided into two gases through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, and the co-production of dimethyl oxalate and dimethyl carbonate is carried out.

[0070] Example 3

[0071] The water and acid content in the raw gas MN is less than 100×10 -6 (V / V); MN volume content is 21%; in the CO and MN mixer, the molar ratio of CO to MN is 1:3; the preheating / heater temperature is 110°C; the shell-and-tube dimethyl carbonate synthesis reactor has a reaction pressure of 0.3MPa and a gas space velocity of 6000h -1After the raw gas is fully reacted with Pd-Cu-K-Fe-Mn supported on NaY molecular sieve as a catalyst (1.0% Pd·1.3% Cu·2.0% K·0.05% Fe·0.02% Mn·95.63% NaY by mass percentage), the space-time yield of DMC is 289g / L*h.

[0072] The absorption liquid in the DMC absorption tower has an operating pressure of 80KPaG and an operating temperature of 110℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 0.7MPaG and the operating temperature is 100℃; the operating pressure of the top of the refining tower is 60KPaG and the operating temperature is 100℃; the product of 98.7% dimethyl carbonate produced by the refining tower. The gas phase outlet gas of the DMC absorption tower is divided into two streams through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, so as to produce dimethyl oxalate and dimethyl carbonate.

[0073] Example 4

[0074] The water and acid content in the raw gas MN is less than 100×10 -6 (V / V); MN volume content is 21%; in the CO and MN mixer, the molar ratio of CO to MN is 1:5; the preheating / heater temperature is 120°C; the shell-and-tube dimethyl carbonate synthesis reactor has a reaction pressure of 0.3MPa and a gas space velocity of 7000h -1 After the raw gas is fully reacted with Pd-Cu-K-Mn supported on MCM-41 as a catalyst (1.25% Pd·0.86% Cu·0.05% K·0.83% Mn·97.87% MCM-41 by mass percentage), the space-time yield of DMC is 368g / L*h.

[0075] The absorption liquid in the DMC absorption tower has an operating pressure of 60KPaG and an operating temperature of 100℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 0.9MPaG and the operating temperature is 100℃; the operating pressure of the top of the refining tower is 70KPaG and the operating temperature is 110℃; the product of 97.5% dimethyl carbonate is extracted from the refining tower. The gas phase outlet gas of the DMC absorption tower is divided into two streams through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, so as to produce dimethyl oxalate and dimethyl carbonate.

[0076] Example 5

[0077] The water and acid content in the raw gas MN is less than 100×10 -6(V / V); MN volume content is 24%; in the CO and MN mixer, the molar ratio of CO to MN is 1:6; the preheating / heater temperature is 125°C; the shell-and-tube dimethyl carbonate synthesis reactor has a reaction pressure of 0.4MPa and a gas space velocity of 6000h -1 After the raw gas is fully reacted with Pd-Cu-K-Ag as a catalyst (1.0% Pd·3.0% Cu·0.45% K·0.5% Ag·95.05% mixed molecular sieve, the mixed molecular sieve is NaY and 1.5g NaX molecular sieve), the space-time yield of DMC is 375g / L*h.

[0078] The absorption liquid in the DMC absorption tower has an operating pressure of 80KPaG and an operating temperature of 130℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 0.5MPaG and the operating temperature is 80℃; the operating pressure of the top of the refining tower is 60KPaG and the operating temperature is 120℃; the product of 98.9% dimethyl carbonate produced by the refining tower. The gas phase outlet gas of the DMC absorption tower is divided into two streams through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, so as to produce dimethyl oxalate and dimethyl carbonate.

[0079] Example 6

[0080] The water and acid content in the raw gas MN is less than 100×10 -6 (V / V); MN volume content is 25%; in the CO and MN mixer, the molar ratio of CO to MN is 1:5; the preheating / heating temperature is 120°C; the reaction pressure of the shell-and-tube dimethyl carbonate synthesis reactor is 0.4MPa, and the gas space velocity is 7000h -1 After the raw gas is fully reacted with Pd-Cu-K-Ag as a catalyst (1.0% Pd·3.0% Cu·0.45% K·0.5% Ag·95.05% mixed molecular sieve, the mixed molecular sieve is NaY and 1.5g NaX molecular sieve), the space-time yield of DMC is 401g / L*h.

[0081] The absorption liquid in the DMC absorption tower has an operating pressure of 60KPaG and an operating temperature of 90℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 0.9MPaG and the operating temperature is 70℃; the operating pressure of the top of the refining tower is 70KPaG and the operating temperature is 110℃; the product of dimethyl carbonate produced from the refining tower is 98.2%. The gas phase outlet gas of the DMC absorption tower is divided into two streams through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, so as to produce dimethyl oxalate and dimethyl carbonate.

[0082] Example 7

[0083] The water and acid content in the raw gas MN is less than 100×10 -6 (V / V); MN volume content is 25%; in the CO and MN mixer, the molar ratio of CO to MN is 1:3; the preheating / heater temperature is 110°C; the shell-and-tube dimethyl carbonate synthesis reactor has a reaction pressure of 0.3MPa and a gas space velocity of 6000h -1 After the raw gas is fully reacted with Pd-Cu-K-Eu as a catalyst (0.25% Pd·5.1% Cu·4.3% K·0.57% Eu·89.78% mixed molecular sieve, the mixed molecular sieve is MCM-41 and Naβ molecular sieve), the space-time yield of DMC is 289g / L*h.

[0084] The absorption liquid in the DMC absorption tower has an operating pressure of 80KPaG and an operating temperature of 110℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 0.7MPaG and the operating temperature is 100℃; the operating pressure of the top of the refining tower is 60KPaG and the operating temperature is 100℃; the product of 98.7% dimethyl carbonate produced by the refining tower. The gas phase outlet gas of the DMC absorption tower is divided into two streams through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, so as to produce dimethyl oxalate and dimethyl carbonate.

[0085] Example 8

[0086] The water and acid content in the raw gas MN is less than 100×10 -6 (V / V); MN volume content is 27%; in the CO and MN mixer, the molar ratio of CO to MN is 1:6; the preheating / heating temperature is 110°C; the reaction pressure of the shell-and-tube dimethyl carbonate synthesis reactor is 0.3MPa, and the gas space velocity is 8000h -1 After the raw gas is fully reacted with Pd-Cu-K-Mn supported on MCM-41 as a catalyst (1.25% Pd·0.86% Cu·0.05.% K·0.83% Mn·97.87% MCM-41 by mass percentage), the space-time yield of DMC is 257g / L*h.

[0087] The absorption liquid in the DMC absorption tower has an operating pressure of 75KPaG and an operating temperature of 130℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 1.1MPaG and the operating temperature is 120℃; the operating pressure of the top of the refining tower is 70KPaG and the operating temperature is 100℃; the product of 99.1% dimethyl carbonate produced by the refining tower. The gas phase outlet gas of the DMC absorption tower is divided into two streams through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, so as to produce dimethyl oxalate and dimethyl carbonate.

[0088] Example 9

[0089] The water and acid content in the raw gas MN is less than 100×10 -6 (V / V); MN volume content is 28%; in the CO and MN mixer, the molar ratio of CO to MN is 1:4; the preheating / heating temperature is 125°C; the shell-and-tube dimethyl carbonate synthesis reactor has a reaction pressure of 0.4MPa and a gas space velocity of 8000h -1 After the raw gas is fully reacted with Pd-Cu-K-Eu as a catalyst (0.25% Pd·5.1% Cu·4.3% K·0.57% Eu·89.78 mixed molecular sieves by mass, the mixed molecular sieves are MCM-41 and Naβ molecular sieves), the space-time yield of DMC is 437g / L*h.

[0090] The absorption liquid in the DMC absorption tower has an operating pressure of 60KPaG and an operating temperature of 90℃ at the top of the de-lightening and de-heaving tower; the operating pressure of the top of the pressure tower is 1.2MPaG and the operating temperature is 110℃; the operating pressure of the top of the refining tower is 70KPaG and the operating temperature is 90℃; the product of dimethyl carbonate produced from the refining tower is 98.2%. The gas phase outlet gas of the DMC absorption tower is divided into two streams through a circulating compressor and sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling, so as to produce dimethyl oxalate and dimethyl carbonate.

[0091] The catalysts of Examples 1-9 can be prepared accordingly using the preparation example of the chlorine-free dimethyl carbonate catalyst disclosed in CN116899614A.

[0092] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A production process for co-producing dimethyl oxalate with dimethyl carbonate, characterized in that: The dimethyl carbonate production process uses a chlorine-free dimethyl carbonate catalyst, which is a chlorine-free dimethyl carbonate production process; the dimethyl oxalate production process uses a methyl nitrite esterification regeneration tower for methyl nitrite regeneration, providing methyl nitrite raw materials, and a nitric oxide / methanol / nitric acid oxidation-reduction tower synthesizes methyl nitrite by adding nitric acid for methyl nitrite supplementation, and the circulating gas in the dimethyl oxalate production process is returned to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower for recycling; A top gas from the nitric oxide / methanol / nitric acid redox tower in the dimethyl oxalate production process is used as raw gas for dimethyl carbonate synthesis. After being washed and purified and adjusting the molar ratio of CO to MN in the raw gas to a target ratio, dimethyl carbonate is synthesized through the dimethyl carbonate production process. The circulating gas generated by the dimethyl carbonate synthesis is returned to the esterification regeneration tower and the nitric oxide / methanol / nitric acid redox tower in the dimethyl oxalate production process for recycling.

2. The production process according to claim 1, characterized in that: The molar ratio of CO to MN in the raw gas for the production of dimethyl carbonate is 1:3 to 1:

7.

3. The production process according to claim 1, characterized in that: The volume content of methyl nitrite in the methyl nitrite-rich top gas drawn from the top of the nitric oxide / methanol / nitric acid redox tower is 18-30%.

4. The production process according to claim 1, characterized in that: The volume content of CO in the methyl nitrite-rich overhead gas drawn from the top of the nitric oxide / methanol / nitric acid redox tower is 7-22%.

5. The production process according to claim 1, characterized in that: The combined production process of dimethyl oxalate and dimethyl carbonate includes a production process of dimethyl oxalate DMO and a production process of dimethyl carbonate DMC. In the dimethyl oxalate production process, the MN raw gas washed with methanol produced in the methyl nitrite esterification regeneration tower is preheated / heated to increase the temperature, and then enters the CO and MN mixer, and CO is added to adjust the molar ratio of CO and MN in the raw gas to reach the target ratio required for the production of dimethyl oxalate, and the CO and MN mixed gas reaching the target ratio is sent to the DMO carbonylation reactor, and the catalytic carbonylation reaction is carried out under the DMO carbonylation catalyst, and then the mixed gas enters the DMO absorption tower after the catalytic carbonylation reaction, and the gas phase outlet gas of the DMO absorption tower is sent to the methyl nitrite esterification regeneration tower and the nitric oxide / methanol / nitric acid oxidation-reduction tower, and the liquid phase outlet of the DMO absorption tower collects dimethyl oxalate; In the dimethyl carbonate production process, a gas rich in methyl nitrite is drawn out from the top of a nitric oxide / methanol / nitric acid redox tower, washed with methanol, preheated / heated and heated, and then used as a raw gas for dimethyl carbonate production to enter a CO and MN mixer, the molar ratio of CO and MN in the raw gas is adjusted to reach a target ratio required for dimethyl carbonate production, and the mixed gas of CO and MN reaching the target ratio is sent to a DMC carbonylation reactor, where a catalytic carbonylation reaction is carried out under the catalysis of a chlorine-free dimethyl carbonate carbonylation catalyst, and then the mixed gas enters a DMC absorption tower after the catalytic carbonylation reaction, and the gas phase outlet gas of the DMC absorption tower is sent to a methyl nitrite esterification regeneration tower and a nitric oxide / methanol / nitric acid redox tower in the dimethyl oxalate production process, and dimethyl carbonate DMC is collected at the liquid phase outlet of the DMC absorption tower.

6. The production process according to claim 1 or 5, characterized in that: The gas phase outlet gas of the DMO absorption tower and the gas phase outlet gas of the DMC absorption tower are combined into a circulating raw gas, and the combined circulating raw gas is further divided into two raw gas streams, one of which accounts for 70-90% of the total gas volume and directly enters the inlet of the methyl nitrite esterification regeneration tower; the other enters the inlet of the nitric oxide / methanol / nitric acid oxidation-reduction tower.

7. The production process according to claim 5, characterized in that: In the production of dimethyl oxalate, the outlet gas of the methyl nitrite esterification regeneration tower and the outlet gas of the DMO carbonylation reactor are preheated and heated by heat exchange, and then sent to the DMO carbonylation reactor for reaction. The outlet gas of the DMO carbonylation reactor enters the DMO absorption tower after heat exchange; In the production of dimethyl carbonate, the methyl nitrite-rich top gas drawn out from the nitric oxide / methanol / nitric acid redox tower and the outlet gas of the DMC carbonylation reactor are preheated and heated by heat exchange and sent to the DMC carbonylation reactor for reaction. The outlet gas of the DMC carbonylation reactor enters the DMC absorption tower after heat exchange.

8. The production process according to claim 5, characterized in that: The DMO absorption tower is a methanol absorption tower. The gas at the outlet of the DMO carbonylation reactor enters the methanol absorption tower after heat exchange and cooling in a cooler, and absorbs the DMO product with methanol. The DMC absorption tower is a methanol absorption tower. The gas at the outlet of the DMC carbonylation reactor enters the methanol absorption tower after heat exchange and cooling by a cooler, and the DMC product is absorbed by methanol.

9. The production process according to claim 5, characterized in that: A methanol recovery tower is provided, and the liquid phase outlet of the nitric oxide / methanol / nitric acid redox tower is connected to the inlet of the methanol recovery tower for recovering methanol.

10. The production process according to claim 9, characterized in that: The liquid phase in the methyl nitrite esterification regeneration tower directly enters the nitric oxide / methanol / nitric acid oxidation-reduction tower, and the liquid phase in the nitric oxide / methanol / nitric acid oxidation-reduction tower directly enters the methanol absorption tower, that is, the liquid phases in the two towers are finally mixed together and enter the methanol recovery tower to recover methanol.

11. The production process according to claim 5, characterized in that: The DMC carbonylation reactor is a shell-and-tube reactor, in which a chlorine-free dimethyl carbonate catalyst is loaded. The shell-and-tube reactor uses hot water circulation to transfer heat and produces low-pressure steam for preheating / heating. The reaction pressure is 0.3-0.5 MPa, and the gas space velocity is 3000-8000 h -1 ; The reaction temperature of the DMC carbonylation reactor is 100-130°C; The overhead gas from the nitric oxide / methanol / nitric acid redox tower is passed through a methanol washing purification tower to remove water and acid content in the raw gas to less than 100×10 -6 (V / V).

12. A production system for the production process of dimethyl oxalate and dimethyl carbonate according to any one of claims 1 to 5, characterized in that: The production system comprises a DMO synthesis system and a DMC synthesis system, The DMO synthesis system includes a methyl nitrite esterification regeneration tower, a nitric oxide / methanol / nitric acid oxidation-reduction tower, a first heater, a first CO and MN mixer, a DMO carbonylation reactor, a circulation compressor, a DMO absorption tower, and a first liquid phase separation system. The top outlet of the methyl nitrite esterification regeneration tower is connected to the inlet of the first heater, the outlet of the first heater is connected to the inlet of the first CO and MN mixer, the outlet of the first CO and MN mixer is connected to the inlet of the DMO carbonylation reactor, the outlet gas of the DMO carbonylation reactor is connected to the inlet of the DMO absorption tower after heat exchange cooling, the gas phase outlet of the DMO absorption tower is connected to the inlet of the methyl nitrite esterification regeneration tower and the redox tower through a circulating compressor, and the liquid phase outlet of the DMO absorption tower is connected to the first liquid phase separation system for refining dimethyl oxalate; The DMC synthesis system includes a methanol washing and purification tower, a second heater, a second CO and MN mixer, a DMC carbonylation reactor, a circulating compressor, a DMC absorption tower, and a second liquid phase separation system. The outlet of the nitric oxide / methanol / nitric acid redox tower of the DMO synthesis system is connected to the inlet of the methanol washing and purification tower, the gas phase outlet of the methanol washing and purification tower is connected to the inlet of the second heater, the outlet of the second heater is connected to the inlet of the second CO and MN mixer, the outlet of the second CO and MN mixer is connected to the inlet of the DMC carbonylation reactor, the outlet gas of the DMC carbonylation reactor enters the DMC absorption tower after heat exchange cooling, the gas phase outlet of the DMC absorption tower is connected to the inlet of the methyl nitrite regeneration tower and the inlet of the nitric oxide / methanol / nitric acid redox tower through a circulating compressor, the circulating compressor of the DMO synthesis system and the DMC synthesis system is shared, and the liquid phase outlet of the DMC absorption tower is connected to the second liquid phase separation system for refining dimethyl carbonate.

13. The production system according to claim 12, characterized in that: The DMO synthesis system further comprises a first heat exchanger, wherein the cold end inlet of the first heat exchanger is connected to the outlet of the methyl nitrite esterification regeneration tower, the cold end outlet is connected to the inlet of the first CO and MN mixer, the hot end inlet of the first heat exchanger is connected to the gas phase outlet of the DMO carbonylation reactor, and the hot end outlet of the first heat exchanger is connected to the DMO absorption tower, and the outlet gas of the methyl nitrite esterification regeneration tower and the outlet gas of the DMO carbonylation reactor are preheated and heated by heat exchange and temperature raising, and then sent to the DMO carbonylation reactor for reaction; The DMC synthesis system also includes a second heat exchanger, the cold end inlet of the second heat exchanger is connected to the outlet of the methanol washing and purification tower, the cold end outlet is connected to the inlet of the second CO and MN mixer, the hot end inlet of the second heat exchanger is connected to the gas phase outlet of the DMC carbonylation reactor, and the hot end outlet of the second heat exchanger is connected to the DMC absorption tower. The top gas rich in methyl nitrite drawn out of the nitric oxide / methanol / nitric acid oxidation-reduction tower and the outlet gas of the DMC carbonylation reactor are preheated and heated by heat exchange and sent to the DMC carbonylation reactor for reaction.

14. The production system according to claim 12, characterized in that: It also includes a methanol recovery tower, wherein the liquid phase outlet of the nitric oxide / methanol / nitric acid redox tower is connected to the inlet of the methanol recovery tower for recovering methanol; The first liquid phase separation system comprises a light-heavy removal tower, a first pressurizing tower and a first refining tower, the liquid phase outlet of the DMO absorption tower is connected to the inlet of the first light-heavy removal tower, the outlet of the first light-heavy removal tower is connected to the inlet of the first pressurizing tower, and the outlet of the pressurizing tower is connected to the inlet of the first refining tower; The second liquid phase separation system includes a second light-heavy degassing tower, a second pressurizing tower, a second refining tower, and a melt crystallization device. The liquid phase outlet of the DMC absorption tower is connected to the inlet of the second light-heavy degassing tower, the outlet of the second light-heavy degassing tower is connected to the inlet of the second refining tower, and the inlet of the second refining tower is connected to the melt crystallization device.

15. The production system according to claim 14, characterized in that: The liquid phase outlet in the methyl nitrite esterification regeneration tower is connected to the liquid phase inlet of the nitric oxide / methanol / nitric acid redox tower, directly enters the nitric oxide / methanol / nitric acid redox tower, merges with the liquid phase in the nitric oxide / methanol / nitric acid redox tower, and then enters the methanol absorption tower, that is, the liquid phases in the two towers are finally mixed and enter the methanol recovery tower to recover methanol.

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