A method for the continuous synthesis of dimethyl sulfate

Abstract

The application provides a method for continuously synthesizing dimethyl sulfate, which uses a reaction system provided by the application to continuously synthesize dimethyl sulfate, and comprises the following steps: simultaneously dissolving and absorbing SO3 and dimethyl ether into crude dimethyl sulfate stored in a first absorption circulating tank and a first reaction circulating tank respectively to form two kinds of absorption liquid, absorption liquid 1 for absorbing dimethyl ether and absorption liquid 2 for absorbing SO3; then conveying the absorption liquid 2 to the first reaction circulating tank storing the absorption liquid 1 to generate dimethyl sulfate through esterification; and conveying the unreacted materials to a second reaction circulating tank and a second absorption circulating tank in sequence for continuous reaction. The method has the advantages of simple process, reduced energy consumption, saved cost, continuous production process, no production problems such as running, leaking, dripping and leaking, and the like, and provides guarantee for realizing large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of chemical preparation technology, specifically to a method for the continuous synthesis of dimethyl sulfate. Background Technology

[0002] Dimethyl sulfate is an important chemical intermediate and methylating agent, widely used in various industries including pharmaceuticals, agriculture, textiles, construction, petrochemicals, papermaking, food processing, and the production of daily chemical products. Currently, the most common method for synthesizing dimethyl sulfate is the esterification reaction between sulfur trioxide (SO3) and dimethyl ether (DME).

[0003] Patent document CN109748827A discloses a process for the continuous synthesis of dimethyl sulfate. In this process, sulfur trioxide and dimethyl ether are successively absorbed by crude dimethyl sulfate in different sections of a three-stage esterification reaction tower, where they come into contact and react to produce dimethyl sulfate. The product is then obtained through degassing and distillation separation, along with the byproduct methyl hydrogen sulfate.

[0004] Patent document CN1086209A discloses a method and equipment for preparing sulfuric acid ester by burning sulfur in dry air. The method is characterized by being composed of a fan, a freeze-zeolite adsorption unit, a sulfur combustion furnace, a conversion tower, an absorption tower, an etherification tank, and an esterification tank. Pre-cooled and dried air reacts with burning sulfur to produce dry sulfur dioxide gas, which is then converted into 9-11% sulfur trioxide gas. Dimethyl sulfate is used as an absorption solvent, and then it is esterified with dimethyl ether to produce dimethyl sulfate.

[0005] Patent document CN103570590A discloses an apparatus for generating dimethyl sulfate, including an esterification reaction tower, a degassing tower, and a distillation tower. The top inlet of the esterification reaction tower is connected to a liquid material source via a pipeline, the material outlet of the esterification reaction tower at the bottom is connected to the degassing tower inlet in the middle of the degassing tower via a pipeline, the top outlet of the distillation tower is connected to an external first storage tank via a pipeline, the side outlet of the upper part of the distillation tower is connected to an external second storage tank via a pipeline, and the degassing tower outlet at the top of the degassing tower is connected to the absorption tower inlet of the absorption tower via a pipeline.

[0006] Patent document CN109748827A discloses a process and equipment for the continuous synthesis of dimethyl sulfate. Sulfur trioxide and dimethyl ether (DME) are successively absorbed by crude dimethyl sulfate in different sections of a three-stage esterification reaction tower, reacting to form dimethyl sulfate. The product, dimethyl sulfate, and the byproduct methyl hydrogen sulfate are then obtained through degassing and distillation separation. The process includes a continuous synthesis reaction and degassing and distillation processes. The continuous synthesis reaction occurs in a three-stage esterification reaction tower, which is divided into three sections: an SO3 absorption section, a DME absorption esterification section, and an aging section. The DME absorption esterification section and the aging section of the three-stage esterification reaction tower are equipped with multiple tower-stage components distributed along the inner wall of the tower body, forming a fan-shaped structure.

[0007] However, the above-mentioned existing technologies generally have the following defects: (1) The reaction of sulfur trioxide, dimethyl ether and dimethyl sulfate is all in one reactor, the controllability of the reaction is poor, and it is easy to cause violent reaction, overheating, and excessive reaction speed, resulting in many side reactions and impurities; (2) Dimethyl ether is a flammable gas and sulfur trioxide is a strong oxidant. When the two are dissolved in dimethyl sulfate at the same time and undergo esterification reaction, they may cause an explosive reaction due to local overheating, which may lead to safety accidents; (3) The reaction of sulfur trioxide and dimethyl ether is incomplete and the utilization rate is low. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the present invention provides a method for the continuous synthesis of dimethyl sulfate, which enables continuous production, ensures a thorough and uniform esterification reaction, has a fast reaction rate, high production efficiency, high yield, high product purity, saves energy and reduces consumption, lowers product acidity, and produces dimethyl sulfate safely and environmentally friendly.

[0009] In a first aspect, the present invention provides a reaction system for the continuous synthesis of dimethyl sulfate, comprising an absorption module one, an absorption module two, a reaction module one, and a reaction module two;

[0010] The absorption module one and absorption module two respectively include an absorption tower (e.g., a primary absorption tower and a secondary absorption tower), a circulation tank (e.g., a primary absorption circulation tank and a secondary absorption circulation tank), a circulation pump (e.g., a primary absorption circulation pump and a secondary absorption circulation pump), and a cooler (e.g., a primary absorption cooler and a secondary absorption cooler). The absorption tower, circulation tank, circulation pump, and cooler in each absorption module are sequentially connected to form a circulation. The reaction module one and reaction module two respectively include a reaction tower (e.g., a primary reaction tower and a secondary reaction tower), a circulation tank (e.g., a primary reaction circulation tank and a secondary reaction circulation tank), a circulation pump (e.g., a primary reaction circulation pump and a secondary reaction circulation pump), and a cooler (e.g., a primary reaction cooler and a secondary reaction cooler). The reaction tower, circulation tank, circulation pump, and cooler in each reaction module are sequentially connected to form a circulation.

[0011] The absorption module one is connected to the reaction module one, the reaction module one is connected to the reaction module two, and the reaction module two is connected to the absorption module two.

[0012] Sulfur trioxide is fed from the first absorption module, and dimethyl ether is fed from the first reaction module.

[0013] Furthermore, dimethyl ether can also be fed from the second reaction module and / or the second absorption module.

[0014] Furthermore, crude dimethyl sulfate can be fed from absorption module one, absorption module two, reaction module one, and reaction module two.

[0015] Furthermore, the reaction system also includes a pipeline module.

[0016] Furthermore, the pipeline module includes a sulfur trioxide feed pipeline, a dimethyl ether feed pipeline, a crude dimethyl sulfate feed pipeline, a tail gas conveying pipeline, and a product conveying pipeline.

[0017] Furthermore, the sulfur trioxide feed pipeline is connected to the absorption tower in absorption module one; the dimethyl ether feed pipeline is connected to the circulation tanks of absorption module two, reaction module one, and reaction module two, respectively; the crude dimethyl sulfate feed pipeline is connected to the circulation tanks of absorption module one, absorption module two, reaction module one, and reaction module two, respectively; the tail gas conveying pipeline is connected to the absorption tower of absorption module two; and the product conveying pipeline is connected to the circulation tank of reaction module one.

[0018] Furthermore, in the first absorption module, the bottom of the absorption tower is connected to the top of the circulation tank, the circulation pump is connected to the bottom of the condenser, and the top of the condenser is connected to the upper part of the absorption tower.

[0019] Furthermore, in the second absorption module, the bottom of the absorption tower is connected to the top of the circulation tank, the circulation pump is connected to the bottom of the condenser, and the top of the condenser is connected to the upper part of the absorption tower.

[0020] Furthermore, in the first reaction module, the bottom of the reaction tower is connected to the top of the circulation tank, the circulation pump is connected to the bottom of the condenser, and the top of the condenser is connected to the upper part of the absorption tower.

[0021] Furthermore, in the second reaction module, the bottom of the reaction tower is connected to the top of the circulation tank, the circulation pump is connected to the bottom of the condenser, and the top of the condenser is connected to the upper part of the absorption tower.

[0022] Furthermore, the absorption tower of absorption module one can be connected to the absorption tower of absorption module two, and can be used to receive incompletely absorbed sulfur trioxide;

[0023] Furthermore, the reaction tower of reaction module one can be connected to the reaction tower of reaction module two, and can be used to receive dimethyl ether or sulfur trioxide that has not been completely absorbed and / or reacted;

[0024] Furthermore, the reaction tower of the reaction module two can be connected to the absorption tower of the absorption module two, and can be used to receive dimethyl ether or sulfur trioxide that has not been completely absorbed and / or reacted.

[0025] Furthermore, the circulation tank of the first absorption module is also connected to the second absorption module, the first reaction module, and the second reaction module, respectively;

[0026] Furthermore, the circulation tank of the second absorption module is also connected to the first absorption module, the first reaction module, and the second reaction module, respectively;

[0027] Furthermore, the circulation tank of the first reaction module is also connected to the first absorption module, the second absorption module, and the second reaction module, respectively;

[0028] Furthermore, the circulation tank of the second reaction module is also connected to the first absorption module, the second absorption module, and the first reaction module, respectively.

[0029] Furthermore, the sulfur trioxide feed pipeline is connected to the middle of the absorption tower in absorption module one.

[0030] Furthermore, the dimethyl ether feed line is connected to the top side of the circulation tank of absorption module two, reaction module one, and reaction module two, respectively.

[0031] Furthermore, the exhaust gas delivery pipeline is connected to the top of the absorption tower of the second absorption module.

[0032] Furthermore, the circulation tank can be combined with the absorption tower or the reaction tower to form an integrated reaction vessel.

[0033] Furthermore, the reaction system also includes a product tank and a tail gas treatment device; the product tank is connected to the product delivery pipeline; the tail gas treatment device is connected to the tail gas delivery pipeline.

[0034] Furthermore, both the absorption tower and the reaction tower are packed towers.

[0035] Furthermore, the packing material of the packed tower is ceramic corrugated packing or saddle-shaped ceramic packing.

[0036] Furthermore, the sulfur trioxide is prepared by a pyrite-based acid production process.

[0037] Furthermore, the substance transported by the sulfur trioxide feed pipeline is sulfur trioxide.

[0038] Furthermore, the substance transported by the dimethyl ether feed pipeline is dimethyl ether.

[0039] Furthermore, the substance transported by the crude dimethyl sulfate feed pipeline is crude dimethyl sulfate.

[0040] Furthermore, the exhaust gas delivery pipeline is used to deliver the exhaust gas generated by the reaction.

[0041] Furthermore, the product delivery pipeline is used to deliver the product dimethyl sulfate.

[0042] In a second aspect, the present invention provides a method for the continuous synthesis of dimethyl sulfate, which uses the reaction system described in the first aspect to continuously synthesize dimethyl sulfate. The method includes simultaneously dissolving and absorbing SO3 and dimethyl ether into crude dimethyl sulfate stored in a primary absorption circulation tank and a primary reaction circulation tank, respectively, to form two absorbents, namely absorbent 1 for absorbing dimethyl ether and absorbent 2 for absorbing SO3. Then, absorbent 2 is transported to the primary reaction circulation tank where absorbent 1 is stored to undergo an esterification reaction to generate dimethyl sulfate. Unreacted material is sequentially transported to a secondary reaction circulation tank and a secondary absorption circulation tank for further reaction.

[0043] Further, the method includes the following steps: crude dimethyl sulfate is conveyed to the circulation tanks of absorption module one, absorption module two, reaction module one, and reaction module two until the liquid level reaches 20-40% of the height of the circulation tank (e.g., 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40%); after dimethyl ether is conveyed to the circulation tank of reaction module one, it is dissolved by crude dimethyl sulfate. The process involves decomposition and absorption to obtain absorbent liquid 1. Simultaneously, SO3 is transported to the absorption tower of absorption module one, where it is dissolved and absorbed by crude dimethyl sulfate to obtain absorbent liquid 2. Absorbent liquid 2 enters reaction module one, mixes with absorbent liquid 1, undergoes an esterification reaction, and generates dimethyl sulfate. The unreacted material in reaction module one enters reaction module two to continue the esterification reaction and generate dimethyl sulfate. The unreacted material in reaction module two enters absorption module two to continue the esterification reaction and generate dimethyl sulfate.

[0044] Furthermore, the exhaust gas generated in the method is transported to the exhaust gas treatment device through an exhaust gas delivery pipeline.

[0045] Furthermore, the exhaust gas comprises: 0.01-0.03% SO3, 0.3-0.5% SO2, 3-5% oxygen, trace amounts of dimethyl sulfate and dimethyl ether, and the remainder being nitrogen.

[0046] Furthermore, as the production process continues, the liquid levels in the circulation tanks of absorption module one, absorption module two, reaction module one, and reaction module two continuously rise. When the liquid level rises to 60-80% of the height of the circulation tank (e.g., 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80%), the dimethyl ether switching pipeline delivers it to the circulation tank of reaction module two, while simultaneously delivering the dimethyl sulfate generated in absorption module one, absorption module two, and reaction module two to the circulation tank of reaction module one.

[0047] Furthermore, when the purity of dimethyl sulfate in the circulation tank of reaction module one is ≥99%, it is transferred to the product tank.

[0048] Furthermore, during the process of dimethyl sulfate being transported to the product tank, the liquid levels in the circulation tanks of absorption module one, absorption module two, reaction module one, and reaction module two continuously decrease. When the liquid levels in the circulation tanks of absorption module one, absorption module two, reaction module one, and reaction module two drop to 20-40% of the height of the circulation tank (e.g., 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40%), dimethyl ether is switched to the circulation tank of reaction module one for continued production.

[0049] Furthermore, the acidity of absorption module one, absorption module two, reaction module one, and reaction module two can be controlled by adjusting the dimethyl ether inlet flow rate or the SO3 inlet flow rate.

[0050] Furthermore, the dimethyl sulfate obtained by the method has a purity of ≥99%.

[0051] The reaction system for the continuous synthesis of dimethyl sulfate of this invention includes a multi-stage absorption reactor, which solves the problem of poor reaction controllability. Dimethyl ether and sulfur trioxide are dissolved and absorbed by crude dimethyl sulfate in multiple absorption reactors, respectively, improving the utilization rate of dimethyl ether and sulfur trioxide. At the same time, it effectively prevents direct contact between dimethyl ether and sulfur trioxide, improving the sufficiency and safety of the esterification reaction. The continuous synthesis method of dimethyl sulfate of this invention has a simple process, reduces energy consumption, saves costs, and the continuous production process eliminates production problems such as spills, leaks, and drips, providing a guarantee for large-scale industrial production. The obtained dimethyl sulfate product has a purity of ≥99%. Attached Figure Description

[0052] Figure 1 The diagram shown is a schematic of the reaction system structure.

[0053] Among them, 100-Absorption Module 1, 200-Absorption Module 2, 300-Reaction Module 2, 400-Reaction Module 1; 101-Primary Absorption Tower, 102-Primary Absorption Circulation Tank, 103-Primary Absorption Circulation Pump, 104-Primary Absorption Condenser; 201-Secondary Absorption Tower, 202-Secondary Absorption Circulation Tank, 203-Secondary Absorption Circulation Pump, 204-Secondary Absorption Condenser; 301-Secondary Reaction Tower, 302-Secondary Reaction Circulation Tank, 303-Secondary Reaction Circulation Pump, 304-Secondary Reaction Condenser; 401-Primary Reaction Tower, 402-Primary Reaction Circulation Tank, 403-Primary Reaction Circulation Pump, 404-Primary Reaction Condenser; 501-Sulfur Trioxide Feed Pipeline, 502-Dimethyl Ether Feed Pipeline, 503-Crude Dimethyl Sulfate Feed Pipeline, 504-Tail Gas Conveying Pipeline, 505-Product Conveying Pipeline.

[0054] → indicates that all routes and pipelines are displayed; This indicates that not all pipeline routes are displayed (for example, 100 indicates that the pipeline is connected to 201, 301, and 401). Detailed Implementation

[0055] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0056] All publications, patents, and published patent specifications cited in this article are incorporated herein in their entirety through citation.

[0057] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0059] Example 1

[0060] like Figure 1As shown, the reaction system for the continuous synthesis of dimethyl sulfate includes an absorption module 100, an absorption module 200, a reaction module 200, a reaction module 400, and a pipeline module. The absorption module 100 includes a primary absorption tower 101, a primary absorption circulation tank 102, a primary absorption circulation pump 103, and a primary absorption condenser 104. The absorption module 200 includes a secondary absorption tower 201, a secondary absorption circulation tank 202, a secondary absorption circulation pump 203, and a secondary absorption condenser 204. 4. Reaction module two 300 includes a secondary reaction tower 301, a secondary reaction circulation tank 302, a secondary reaction circulation pump 303, and a secondary reaction condenser 304. Reaction module one 400 includes a primary reaction tower 401, a primary reaction circulation tank 402, a primary reaction circulation pump 403, and a primary reaction condenser 404. The pipeline module includes a sulfur trioxide feed pipeline 501, a dimethyl ether feed pipeline 502, a crude dimethyl sulfate feed pipeline 503, a tail gas conveying pipeline 504, and a product conveying pipeline 505. The packing of the primary absorption tower 101 is ceramic corrugated packing, and the packing of the secondary absorption tower 201, the secondary reaction tower 301, and the primary reaction tower 401 is saddle-shaped ceramic packing.

[0061] In absorption module 100, the bottom of the primary absorption tower 101 is connected to the top of the primary absorption circulation tank 102, one side of the primary absorption circulation tank 102 is connected to the primary absorption circulation pump 103, the primary absorption circulation pump 103 is connected to the bottom of the primary absorption condenser 104, and the top of the primary absorption condenser 104 is connected to the upper part of the primary absorption tower 101. Thus, the primary absorption tower 101, the primary absorption circulation tank 102, the primary absorption circulation pump 103, and the primary absorption condenser 104 are connected in sequence and form a circulation.

[0062] The connection methods of the absorption tower (201) or reaction tower (301, 401), circulation tank (202, 302, 402), circulation pump (203, 303, 403) and condenser (204, 304, 404) in absorption module 200, reaction module 200 and reaction module 100 are the same as those of absorption module 100.

[0063] The top side of the primary absorption circulation tank 102 is connected to the secondary absorption tower 201, the secondary reaction tower 301 and the primary reaction tower 401 respectively. The top side of the secondary absorption circulation tank 202 is connected to the primary absorption tower 101, the secondary reaction tower 301 and the primary reaction tower 401 respectively. The top side of the secondary reaction circulation tank 302 is connected to the primary absorption tower 101, the secondary absorption tower 201 and the primary reaction tower 401 respectively. The top side of the primary reaction circulation tank 402 is connected to the primary absorption tower 101, the secondary absorption tower 201 and the secondary reaction tower 301 respectively.

[0064] The top of the primary absorption tower 101 is connected to the middle of the secondary absorption tower 201, the top of the primary reaction tower 401 is connected to the middle of the secondary reaction tower 301, and the top of the secondary reaction tower 301 is connected to the middle of the secondary absorption tower 201.

[0065] Sulfur trioxide feed line 501 is connected to the middle of the primary absorption tower 101. Dimethyl ether feed line 102 is connected to the top of the secondary absorption circulation tank 202, the secondary reaction circulation tank 302, and the primary reaction circulation tank 402. Crude dimethyl sulfate feed line 503 is connected to the primary absorption circulation tank 102, the secondary absorption circulation tank 202, the secondary reaction circulation tank 302, and the primary reaction circulation tank 402. Tail gas conveying line 504 is connected to the top of the secondary absorption tower 201. Product conveying line 505 is connected to the primary reaction circulation tank 402.

[0066] The reaction system also includes a product tank and an exhaust gas treatment device. The product tank is connected to the product delivery pipeline 505, and the exhaust gas treatment device is connected to the exhaust gas delivery pipeline 504.

[0067] Example 2

[0068] The process for the continuous synthesis of dimethyl sulfate using this reaction system is as follows:

[0069] Crude dimethyl sulfate is fed into the circulation tanks (102, 202, 302, 402) of the four modules until the liquid level reaches 20-40% of the tank height. Dimethyl ether is fed into the primary reaction circulation tank 402, where it is dissolved and absorbed by the crude dimethyl sulfate to obtain absorbent liquid 1. Simultaneously, SO3 is fed into the primary absorption tower 101, where it is dissolved and absorbed by the crude dimethyl sulfate to obtain absorbent liquid 2. The cooling water circulation system (104, 204, 304, 404) is activated to control the temperature of reaction modules one and two within the suitable temperature range for the reaction of sulfur trioxide and dimethyl ether. Absorbent liquid 2 enters reaction module one 400, mixes with absorbent liquid 1, and undergoes an esterification reaction to generate dimethyl sulfate. Unreacted materials in reaction module 1 (400) enter reaction module 2 (300) for further reaction. Unreacted materials in reaction module 2 (300) enter absorption module 2 (200) for further reaction. The tail gas (SO3 content 0.01-0.03%, SO2 content 0.3-0.5%, oxygen 3-5%, trace amounts of dimethyl sulfate and dimethyl ether, the remainder being nitrogen) is transported to the tail gas treatment device through tail gas conveying pipeline 504.

[0070] As the production process continues, the liquid levels in the four circulation tanks (102, 202, 302, 402) rise continuously. When the liquid level reaches 60-80% of the circulation tank height, the dimethyl ether switching pipeline delivers it to the secondary reaction circulation tank 302. Simultaneously, the dimethyl sulfate generated in absorption module 100, absorption module 200, and reaction module 2300 is delivered to the primary reaction circulation tank 402. After sampling and analysis confirms its quality, the dimethyl sulfate product (purity ≥99%) is delivered to the product tank via product delivery pipeline 505. Meanwhile, the liquid levels in the four circulation tanks (102, 202, 302, 402) continuously decrease. When the liquid level in the four circulation tanks (102, 202, 302, 402) drops to 20-40% of the circulation tank height, the dimethyl ether switching pipeline delivers it to the primary reaction circulation tank 402, continuing stable production.

[0071] During the production process, samples are taken and analyzed regularly, and the intake of dimethyl ether is adjusted according to the acidity results to maintain a stable acidity in the system.

[0072] The above production process improves the utilization rate of the two gases, greatly reduces raw material consumption and production costs, the reaction is mild and controllable, there is no overheating or excessively fast reaction, the generated byproducts and impurities are few, the exhaust gas does not require further treatment, greatly reducing waste emissions and treatment costs during the production process, and the process is more environmentally friendly and safe.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0074] The foregoing embodiments and methods described in this invention may vary based on the capabilities, experience, and preferences of those skilled in the art.

[0075] Listing the steps of the method in a certain order in this invention does not constitute any restriction on the order of the method steps.

Claims

1. A method for the continuous synthesis of dimethyl sulfate, comprising a reaction system for the continuous synthesis of dimethyl sulfate, said reaction system comprising an absorption module one (100), an absorption module two (200), a reaction module two (300), and a reaction module one (400), characterized in that, The absorption module one (100) and absorption module two (200) respectively include absorption towers (101, 201), circulation tanks (102, 202), circulation pumps (103, 203) and coolers (104, 204). The absorption towers (101, 201), circulation tanks (102, 202), circulation pumps (103, 203) and coolers (104, 204) in each absorption module are connected in sequence to form a circulation. The reaction module two (300) and reaction module one (400) respectively include reaction towers (301, 401), circulation tanks (302, 402), circulation pumps (303, 403) and coolers (304, 404). The reaction towers (301, 401), circulation tanks (302, 402), circulation pumps (303, 403) and coolers (304, 404) in each reaction module are connected in sequence to form a circulation. The absorption module 1 (100) and the reaction module 1 (400) are connected, the reaction module 1 (400) and the reaction module 2 (300) are connected, and the reaction module 2 (300) and the absorption module 2 (200) are connected. Sulfur trioxide is fed from the first absorption module (100), and dimethyl ether is fed from the first reaction module (400); The method includes dissolving and absorbing dimethyl ether in crude dimethyl sulfate stored in the circulation tank (402) of reaction module one (400) to obtain absorbent 1. At the same time, SO3 is dissolved and absorbed in crude dimethyl sulfate stored in the circulation tank (102) of absorption module one (100) to obtain absorbent 2. Then, absorbent 2 is transported to the circulation tank (402) of reaction module one (400) where absorbent 1 is stored to undergo an esterification reaction to generate dimethyl sulfate. The unreacted material is sequentially transported to the circulation tank (302) of reaction module two (300) and the circulation tank (202) of absorption module two (200) to continue the reaction.

2. The method according to claim 1, characterized in that, Dimethyl ether is also fed from the second reaction module (300) and / or the second absorption module (200).

3. The method according to claim 1, characterized in that, In the first absorption module (100), the bottom of the absorption tower (101) is connected to the top of the circulation tank (102), the circulation pump (103) is connected to the bottom of the condenser (104), and the top of the condenser (104) is connected to the upper part of the absorption tower (101); and / or, In the second absorption module (200), the bottom of the absorption tower (201) is connected to the top of the circulation tank (202), the circulation pump (203) is connected to the bottom of the condenser (204), and the top of the condenser (204) is connected to the upper part of the absorption tower (201); and / or, In the second reaction module (300), the bottom of the reaction tower (301) is connected to the top of the circulation tank (302), the circulation pump (303) is connected to the bottom of the condenser (304), and the top of the condenser (304) is connected to the upper part of the absorption tower (301); and / or, In the first reaction module (400), the bottom of the reaction tower (401) is connected to the top of the circulation tank (402), the circulation pump (403) is connected to the bottom of the condenser (404), and the top of the condenser (404) is connected to the upper part of the absorption tower (401).

4. The method according to claim 1, characterized in that, The reaction tower (401) of reaction module one (400) is connected to the reaction tower (301) of reaction module two (300); and / or, The reaction tower (301) of the second reaction module (300) is connected to the absorption tower (201) of the second absorption module (200); and / or, The circulation tank (102) of the first absorption module (100) is also connected to the second absorption module (200), the first reaction module (400), and the second reaction module (300), respectively; and / or, The circulation tank (202) of the second absorption module (200) is also connected to the first absorption module (100), the first reaction module (400), and the second reaction module (300), respectively; and / or, The circulation tank (302) of the second reaction module (300) is also connected to the first absorption module (100), the second absorption module (200), and the first reaction module (400), respectively; and / or, The circulation tank (402) of the reaction module one (400) is also connected to the absorption module one (100), the absorption module two (200) and the reaction module two (300), respectively.

5. The method according to claim 1, characterized in that, The reaction system also includes a pipeline module, which includes a sulfur trioxide feed pipeline (501), a dimethyl ether feed pipeline (502), a crude dimethyl sulfate feed pipeline (503), a tail gas conveying pipeline (504), and a product conveying pipeline (505).

6. The method according to claim 5, characterized in that, The sulfur trioxide feed pipeline (501) is connected to the absorption tower (101) in the absorption module one (100); The dimethyl ether feed line (502) is connected to the circulation tank (402) of reaction module one (400), and the dimethyl ether feed line (502) is also connected to the circulation tank (202) of absorption module two (200) and / or the circulation tank (302) of reaction module two (300); The crude dimethyl sulfate feed line (503) is connected to the circulation tank (102) of absorption module one (100), the circulation tank (202) of absorption module two (200), the circulation tank (302) of reaction module two (300) and the circulation tank (402) of reaction module one (400), respectively. The exhaust gas delivery pipeline (504) is connected to the absorption tower (201) of the absorption module two (200); The product delivery pipeline (505) is connected to the circulation tank (402) of reaction module one (400).

7. The method according to claim 6, characterized in that, The reaction system also includes product tanks and exhaust gas treatment devices.

8. The method according to claim 7, characterized in that, The product delivery pipeline (505) is connected to the product tank; and / or, The exhaust gas delivery pipeline (504) is connected to the exhaust gas treatment device, and the generated exhaust gas is delivered to the exhaust gas treatment device through the exhaust gas delivery pipeline (504).

9. The method according to claim 1, characterized in that, The absorption tower (101) of absorption module one (100), the absorption tower (201) of absorption module two (200), the reaction tower (301) of reaction module two (300) and the reaction tower (401) of reaction module one (400) are all packed towers.

10. The method according to claim 9, characterized in that, The packing material in the packed tower is ceramic corrugated packing or saddle-shaped ceramic packing.

11. The method according to claim 1, characterized in that, As the production process continues, the liquid levels in the circulation tanks (102, 202, 302, 402) of absorption module one (100), absorption module two (200), reaction module two (300), and reaction module one (400) continuously rise. When the liquid level rises to 60-80% of the height of the circulation tanks (102, 202, 302, 402) of absorption module one (100), absorption module two (200), reaction module two (300), and reaction module one (400), the dimethyl ether switching pipeline transports it to the circulation tank (302) of reaction module two (300), and at the same time, the dimethyl sulfate generated in absorption module one (100), absorption module two (200), and reaction module two (300) is transported to the circulation tank (402) of reaction module one (400).

12. The method according to claim 11, characterized in that, When the purity of dimethyl sulfate in the circulation tank (402) of reaction module one (400) is ≥99%, it is transported to the product tank.

13. The method according to claim 12, characterized in that, During the process of dimethyl sulfate being transported to the product tank, the liquid levels in the circulation tanks (102, 202, 302, 402) of absorption module 1 (100), absorption module 2 (200), reaction module 2 (300), and reaction module 1 (400) continuously decrease. When the liquid levels in the circulation tanks (102, 202, 302, 402) of absorption module 1 (100), absorption module 2 (200), reaction module 2 (300), and reaction module 1 (400) drop to 20-40% of the height of the circulation tanks (102, 202, 302, 402) of absorption module 1 (100), absorption module 2 (200), reaction module 2 (300), and reaction module 1 (400), dimethyl ether is switched to circulation tank (402) of reaction module 1 (400) via pipeline to continue production.

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