A primary synthesis device for directly synthesizing dimethyl carbonate from methanol and carbon dioxide

Abstract

A kind of initial synthesis device for directly synthesizing dimethyl carbonate from methanol and carbon dioxide, comprising: reaction crude separation tower, tower kettle circulating pump, overhead condenser, carbon dioxide feed preheater, steam valve group, carbon dioxide feed valve group, carbon dioxide feed preheater thermometer (T1), carbon dioxide feed preheater pressure gauge (P1), reaction crude separation tower overhead pressure gauge (P2), reaction crude separation tower kettle thermometer (T3) and the like.The utility model discloses a kind of initial synthesis device for directly synthesizing dimethyl carbonate from methanol and carbon dioxide can continuously output dimethyl carbonate crude product, and can guarantee that the yield of dimethyl carbonate crude product is greater than 70%, produces certain economic benefits.

Description

Technical Field

[0001] This utility model relates to the field of dimethyl carbonate production technology, and in particular to a primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Background Technology

[0002] Dimethyl carbonate, also known as methyl carbonate or ethane carbonate, abbreviated as DMC, is a non-toxic, environmentally friendly, and widely used chemical raw material. It is an important organic synthesis intermediate, containing carbonyl, methyl, and methoxy functional groups in its molecular structure, exhibiting diverse reactivity. In production, it is characterized by safety, convenience, low pollution, and easy transportation. DMC not only has low toxicity but also features a high flash point, low vapor pressure, and high lower explosive limit in air. Therefore, it is a green solvent that combines cleanliness and safety, making it a promising "green" chemical product.

[0003] There are various methods for synthesizing dimethyl carbonate, including the phosgene method, methanol oxidative carbonylation method, transesterification method, urea alcoholysis method, and direct synthesis method of methanol and carbon dioxide. At present, most of the dimethyl carbonate production in China adopts the transesterification method. This method has disadvantages such as complex process, high energy consumption in subsequent purification, and difficulty in handling by-products. Summary of the Invention

[0004] This invention addresses the current state of dimethyl carbonate production by proposing a primary synthesis apparatus for the direct synthesis of dimethyl carbonate using methanol and carbon dioxide. This apparatus not only reduces carbon emissions but also avoids the use of highly toxic reactants. The only byproduct is water, and the crude dimethyl carbonate yield can reach over 70%, generating certain economic benefits.

[0005] The technical problem solved by this utility model is to provide a primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The primary synthesis apparatus provided in this application allows for continuous feeding and discharging, continuously producing crude dimethyl carbonate. The raw material, carbon dioxide, is heated to 60°C~80°C by a carbon dioxide feed preheater before entering the reaction crude separation tower. In the catalyst-packed zone in the middle of the reaction crude separation tower, it fully contacts and reacts with methanol. Crude dimethyl carbonate is distilled off from the top of the reaction crude separation tower. The byproduct water reacts with sodium methoxide at the bottom of the reaction crude separation tower. The products are partially circulated with the tower bottom liquid by a tower bottom circulation pump, and partially transported to a tower bottom liquid recovery system for recycling. This application provides a primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide, comprising: a reaction crude separation tower, a reboiler circulating pump, a tower top condenser, a carbon dioxide feed preheater, a steam valve group, a carbon dioxide feed valve group, a carbon dioxide feed preheater thermometer T1, a carbon dioxide feed preheater pressure gauge P1, a reaction crude separation tower top pressure gauge P2, and a reaction crude separation tower reboiler thermometer T3, etc. The raw material methanol is connected to the upper feed end of the crude reaction separation tower, the sodium methoxide feed liquid is connected to the lower feed end of the crude reaction separation tower, the raw material carbon dioxide is connected to the feed end of the carbon dioxide feed preheater, the discharge end of the carbon dioxide feed preheater is connected to the feed end of the crude reaction separation tower, the discharge end of the crude reaction separation tower bottom is connected to the feed end of the bottom circulating pump, the discharge end of the bottom circulating pump is connected to the circulating feed end of the crude reaction separation tower and the bottom liquid recovery system, the top discharge port of the crude reaction separation tower is connected to the feed end of the top condenser, the liquid phase outlet of the top condenser is connected to the crude dimethyl carbonate treatment system, and the gas phase outlet of the top condenser is connected to the carbon dioxide recovery system.

[0006] The bottom of the crude separation column is equipped with a thermometer T3, which is remotely interlocked with the steam valve group via DCS automatic control. The opening of the steam valve group controls the temperature of the thermometer in the bottom of the crude separation column to be between 80 and 100°C. When the temperature of the bottom of the crude separation column is below 80°C, the opening of the steam valve group is increased to increase the steam flow rate and raise the temperature of the liquid in the bottom of the column. When the temperature of the bottom of the crude separation column is above 100°C, the opening of the steam valve group is decreased to reduce the steam flow rate, thus ensuring that the temperature of the bottom of the crude separation column is between 80 and 100°C. This prevents the increase of side reactions due to excessively high temperatures and also prevents the slow reaction rate due to excessively low temperatures, which would reduce the yield of crude dimethyl carbonate.

[0007] The top of the crude separation tower is equipped with a pressure gauge P2, which is remotely controlled by a DCS automatic interlock system via the carbon dioxide feed valve group. The opening of the carbon dioxide feed valve group controls the pressure P2 at the top of the crude separation tower between 50 and 80 kPaG. When the pressure at the top of the crude separation tower is below 50 kPaG, the carbon dioxide feed rate can be increased by opening the carbon dioxide feed valve group, thereby increasing the pressure at the top of the tower. When the pressure at the top of the crude separation tower is above 80 kPaG, the carbon dioxide feed rate can be reduced by closing the carbon dioxide feed valve group, thus ensuring that the pressure at the top of the crude separation tower is between 50 and 80 kPaG. This ensures the smooth progress of the reaction, prevents safety hazards caused by excessive pressure, and avoids increasing the load on subsequent processes.

[0008] This utility model has the following advantages: (1) It can achieve continuous feeding and continuous discharge, thereby improving the yield of crude dimethyl carbonate; (2) This initial synthesis unit is partially controlled by DCS, which simplifies the process operation; (3) This initial synthesis device realizes the reaction and initial separation in one device, which saves equipment investment and shortens the process flow. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the device of this utility model. Detailed Implementation

[0010] The present invention will be further described below with reference to examples. These embodiments are intended to illustrate the present invention and not to limit it. In view of the current status of direct synthesis of dimethyl carbonate from methanol and carbon dioxide, the present invention provides a primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide, including a reaction crude separation tower, a reboiler circulating pump, a tower top condenser, a carbon dioxide feed preheater, a steam valve group, a carbon dioxide feed valve group, a carbon dioxide feed preheater thermometer T1, a carbon dioxide feed preheater pressure gauge P1, a reaction crude separation tower top pressure gauge P2, and a reaction crude separation tower reboiler thermometer T3, etc.

[0011] The raw material methanol is connected to the upper feed end of the crude reaction separation tower, the sodium methoxide feed liquid is connected to the lower feed end of the crude reaction separation tower, the raw material carbon dioxide is connected to the feed end of the carbon dioxide feed preheater, the discharge end of the carbon dioxide feed preheater is connected to the feed end of the crude reaction separation tower, the discharge end of the crude reaction separation tower bottom is connected to the feed end of the bottom circulating pump, the discharge end of the bottom circulating pump is connected to the circulating feed end of the crude reaction separation tower and the bottom liquid recovery system, the top discharge port of the crude reaction separation tower is connected to the feed end of the top condenser, the liquid phase outlet of the top condenser is connected to the crude dimethyl carbonate treatment system, and the gas phase outlet of the top condenser is connected to the carbon dioxide recovery system.

[0012] The bottom of the crude reaction separator is equipped with a thermometer T3, which is remotely controlled by a DCS automatic interlock with the steam valve group. The opening of the steam valve group controls the temperature of the thermometer in the bottom of the crude reaction separator to be between 80 and 100°C. The top of the crude reaction separator is equipped with a pressure gauge P2, which is remotely controlled by a DCS automatic interlock with the carbon dioxide feed valve group. The opening of the carbon dioxide feed valve group controls the pressure at the top of the crude reaction separator P2 to be between 50 and 80 kPaG.

[0013] The raw material carbon dioxide is preheated by the carbon dioxide feed preheater and then enters the reaction crude separation tower. It fully contacts and reacts with the methanol entering the reaction crude separation tower in the catalyst packed section. Crude dimethyl carbonate is directly distilled off from the top of the tower, while water reacts with sodium methoxide in the bottom of the tower. The water is then partially recycled by the bottom circulation pump and partially transported to the recovery system for treatment.

[0014] A primary synthesis apparatus for crude dimethyl carbonate with an annual production capacity of 500 tons / year was tested. The test results showed that, using the primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide provided by this invention, the yield of crude dimethyl carbonate can reach over 70%. The above embodiments are merely one implementation of the primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide according to this invention. Any modifications to the scheme provided by this invention, including adding or subtracting components or steps, or applying this invention to similar technical fields, all fall within the protection scope of this invention.

Claims

1. A primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide, comprising: The system includes a crude separation tower, a reboiler circulating pump, a top condenser, a carbon dioxide feed preheater, a steam valve group, a carbon dioxide feed valve group, a carbon dioxide feed preheater thermometer (T1), a carbon dioxide feed preheater pressure gauge (P1), a top pressure gauge (P2) for the crude separation tower, and a reboiler thermometer (T3) for the crude separation tower. The raw material methanol is connected to the upper feed end of the crude separation tower, the sodium methoxide feed is connected to the lower feed end, the raw material carbon dioxide is connected to the feed end of the carbon dioxide feed preheater, the outlet end of the carbon dioxide feed preheater is connected to the feed end of the crude separation tower, the reboiler outlet is connected to the feed end of the reboiler circulating pump, the reboiler circulating pump outlet is connected to both the reboiler circulating feed end and the reboiler liquid recovery system, the top outlet of the crude separation tower is connected to the feed end of the top condenser, the liquid phase outlet of the top condenser is connected to the dimethyl carbonate crude product treatment system, and the gas phase outlet of the top condenser is connected to the carbon dioxide recovery system.

2. The primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide according to claim 1, characterized in that, The top of the crude reaction separation tower is equipped with a pressure gauge (P3), which is remotely interlocked with the carbon dioxide feed valve group via DCS. The opening degree of the carbon dioxide feed valve group controls the pressure of the crude reaction separation tower. The bottom of the crude reaction separation tower is equipped with a thermometer (T3), which is remotely interlocked with the steam valve group via DCS. The opening degree of the steam valve group controls the temperature of the bottom of the crude reaction separation tower. This ensures the smooth progress of the reaction and can improve the yield of crude dimethyl carbonate.

3. The primary synthesis apparatus for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide according to claim 1, characterized in that, The reaction crude separation tower is filled with catalyst in the middle, which can realize continuous reaction and continuous discharge, and improve the yield of crude dimethyl carbonate.

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