A product separation and purification apparatus and method for the CO esterification of methyl formate

Abstract

This invention discloses a product separation and purification apparatus and method for the production of methyl formate via CO esterification. The apparatus includes a reaction product separator, a DMO stripping column, a methanol absorption column, an MF separation column, an MF stripping column, an MF purification column, and a DMO rectification column. The methanol absorption column has one or more absorbent inlets at its upper part. The outlet of the methanol absorption column is connected to the inlet of the MF separation column, and the outlet of the MF separation column is connected to the inlet of the DMO rectification column, or both the inlet of the DMO rectification column and the absorbent inlet of the methanol absorption column. The outlet of the MF stripping column is connected to the upper inlet of the MF separation column, and the bottom outlet of the MF stripping column is connected to the inlet of the MF purification column. This invention is mainly used for the product separation and purification of methyl formate produced via CO esterification, and features a reasonable process and low energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology. Specifically, it relates to a separation and purification apparatus and method for a reaction product system of CO esterification to produce methyl formate (MF). Background Technology

[0002] Methyl formate (HCOOCH3) can be used directly as a fumigant and bactericide for treating tobacco, dried fruit, grains, etc.; it is also commonly used as a solvent for nitrocellulose and cellulose acetate; in medicine, it is commonly used as a raw material for the synthesis of drugs such as sulfonated methylpyrimidine, sulfonated methoxypyrimidine, and the antitussive dextromethorphan; in the automotive industry, it is used as a curing agent for phenolic resins; and in the polyurethane industry, it is used as a green and environmentally friendly foaming agent.

[0003] In addition, methyl formate is an extremely important intermediate in C1 chemistry (belonging to organic chemical raw materials). Starting from methyl formate, more than 50 products can be produced, including formic acid, acetic acid, ethylene glycol, methyl acrylate, methyl propionate, methyl glycolate, methyl isobutyrate, methyl methacrylate, N-formylmorpholine, N-methylformamide, N,N-dimethylformamide, and high-purity CO.

[0004] The main industrial production technologies for methyl formate include methanol formate esterification and liquid-phase methanol carbonylation. The former is outdated, energy-intensive, and causes severe equipment corrosion, and has been phased out abroad, although some domestic manufacturers still use it. Currently, the mainstream industrial technology is liquid-phase methanol carbonylation, developed and industrialized by BASF in Germany in the 1980s. This method has high selectivity, with methyl formate being the only product (CH3OH+CO=HCOOCH3). However, this technical route uses sodium methoxide as a catalyst, which has serious drawbacks: (1) Sodium methoxide is extremely sensitive to water, so the requirements for the content of impurities such as water and sulfides in the raw materials are extremely strict, usually requiring the impurity content to be ≤1ppm(w); (2) Sodium methoxide is a strong base, which will cause serious corrosion of equipment. The reactor needs to be lined with titanium alloy, resulting in high equipment investment; (3) Homogeneous reaction is carried out in batch reactors, which cannot achieve large-scale continuous production, and the separation of catalyst and product is difficult; (4) The reaction conditions are harsh, with the reaction pressure reaching 4MPa; (5) Sodium methoxide has low solubility in methyl formate, and sodium methoxide is easy to precipitate to form solid precipitates, which can clog pipes and valves, causing great trouble to actual production operations.

[0005] Chinese patent CN103951558B discloses an apparatus, process, and online catalyst evaluation method for the gas-phase methanol carbonylation production of methyl formate. This technology utilizes a fixed-bed reactor at atmospheric pressure, and the catalyst does not have high requirements for the purity of the feed gas, thus solving the technical problems existing in BASF's liquid-phase methanol carbonylation method. The reaction principle of gas-phase methanol carbonylation for the production of methyl formate is as follows:

[0006] 2CH3OH+2NO+0.5O2 → 2CH3ONO+H2O (a)

[0007] 2CO+H2+2CH3ONO → 2HCOOCH3+2NO (b)

[0008] 2CH3OH+2CO+H2+0.5O2 → 2HCOOCH3+H2O (c)

[0009] 2CH3ONO + H2 → 2CH3OH + 2NO (d)

[0010] Reaction (a) involves the formation of methyl nitrite from nitric oxide in the circulating gas, requiring no catalyst. Reaction (b) is the main reaction for the production of methyl formate, using a noble metal heterogeneous catalyst. Reaction (c) is the combined reaction of (a) and (b). Reaction (d) is a side reaction. From the overall reaction (c), it can be seen that the raw materials for the gas-phase methanol carbonylation synthesis of methyl formate are methanol, carbon monoxide, hydrogen, and oxygen. Reaction (b) simultaneously generates nitric oxide, which, in conjunction with reaction (a), forms a cyclic reaction between nitric oxide and methyl nitrite.

[0011] Chinese patent CN103694116B discloses a method for synthesizing methyl formate by gas-phase methanol carbonylation. The catalyst used is a supported nano-platinum group metal heterogeneous catalyst, comprising a platinum group metal active component, a support, and preferred additives. The platinum group metal active component is an alloy or mixture of any two of ruthenium, rhodium, palladium, osmium, iridium, and platinum; the additive is any one or two metals or oxides of iron, cobalt, nickel, and copper; the support is any one or a mixture of two of alumina, silicon oxide, magnesium oxide, zinc oxide, zirconium oxide, titanium dioxide, metal-organic framework compounds, activated carbon, molecular sieves, carbon nanotubes, and graphene; the percentage content of the active component, based on the mass of the support, is 0.01%-2%, preferably 0.1%-1%, and the percentage content of the additive is less than or equal to 20%, preferably 1%-10%.

[0012] Chinese patent CN103691451B discloses a catalyst for the gas-phase methanol carbonylation synthesis of methyl formate, its preparation method, and its application. It provides a supported nano-platinum group metal heterogeneous catalyst, which exhibits good stability, low requirements for impurity content in the feed gas, no corrosion to equipment, and easy separation of the catalyst from the product. The patent also discloses a method for preparing the supported nano-platinum group metal heterogeneous catalyst for the gas-phase methanol carbonylation synthesis of methyl formate.

[0013] The aforementioned patent provides a reaction route, catalyst performance and preparation method, product composition, and separation scheme suitable for laboratory scale and equipment for CO esterification to methyl formate (also known as: gas phase methanol carbonylation to methyl formate). However, it does not propose a feasible engineering technology route suitable for industrialization. Summary of the Invention

[0014] The purpose of this invention is to propose a complete and industrially suitable product separation and purification method and system for the CO (carbon monoxide) esterification to methyl formate (MF) reaction system, which features a reasonable process and low energy consumption.

[0015] The synthesis of methyl formate by CO esterification: Under conditions of 110~150℃ and 0.2~0.7MPag, the following reaction occurs in the presence of a supported metal nanocatalyst:

[0016] 2CO+H2+2CH3ONO (MN) → 2HCOOCH3 (MF) +2NO

[0017] 2CO+2CH3ONO (MN) → C4H6O4 (DMO)+2NO

[0018] The yields of methyl formate (MF) and dimethyl oxalate (DMO) can be altered by controlling reaction conditions and reactant concentrations (two schemes), allowing for adjustments to the product scheme based on market demand.

[0019] This invention provides a product separation and purification apparatus and method for the production of methyl formate via CO esterification, the specific technical solution of which is as follows.

[0020] This invention provides a product separation and purification apparatus for the production of methyl formate via CO esterification. The apparatus comprises a reaction product separator, a DMO stripping column, a methanol absorption column, an MF separator, an MF stripping column, an MF purification column, and a DMO rectification column. An MF product feed line is connected to the inlet of the reaction product separator. The bottom outlet of the reaction product separator is connected to the inlet of the DMO stripping column. The top outlet of the reaction product separator is connected to the inlet of the methanol absorption column. The top outlet of the DMO stripping column is connected to the inlet of the methanol absorption column. One or more absorbent inlets are provided at the top of the methanol absorption column, and a circulation system is provided at the top of the methanol absorption column. The methanol absorber has a gas outlet at the bottom, which is connected to the inlet of the MF separation tower. The MF separation tower has a gas outlet at the top, and the MF separation tower has a bottom outlet connected to the inlet of the DMO distillation tower, or connected to both the inlet of the DMO distillation tower and the upper absorbent inlet of the methanol absorber. The MF separation tower has a side outlet at the top, which is connected to the inlet of the MF stripping tower. The top outlet of the MF stripping tower is connected to the upper inlet of the MF separation tower. The bottom outlet of the MF stripping tower is connected to the inlet of the MF refining tower. The MF refining tower has a top MF product outlet and a bottom MF refining tower outlet. The DMO distillation tower has a bottom DMO stream outlet and a top outlet.

[0021] In this invention, the bottom outlet of the MF separation tower is preferably connected to the middle inlet of the DMO distillation tower and the upper absorbent inlet of the methanol absorption tower, respectively.

[0022] Preferably, the bottom outlet of the reaction product separator is connected to the upper inlet of the DMO stripping tower, the top outlet of the reaction product separator is connected to the lower inlet of the methanol absorption tower, the top outlet of the DMO stripping tower is connected to the lower inlet of the methanol absorption tower, the bottom outlet of the methanol absorption tower is connected to the middle inlet of the MF separation tower, the bottom outlet of the MF separation tower is connected to the middle inlet of the DMO rectification tower, the side outlet of the MF separation tower is connected to the upper inlet of the MF stripping tower, and the bottom outlet of the MF stripping tower is connected to the upper middle inlet of the MF refining tower.

[0023] The present invention discloses a product separation and purification device for the production of methyl formate by CO esterification, wherein the upper inlet of the MF separation tower is located above the upper side outlet of the MF separation tower.

[0024] The present invention discloses a product separation and purification device for the production of methyl formate by CO esterification, wherein three absorbent inlets are preferably provided at the top of the methanol absorption tower.

[0025] The present invention discloses a product separation and purification device for the production of methyl formate by CO esterification. The methanol absorption tower is a packed tower, a plate tower, or a composite tower of packed tower and plate tower. It is preferred to use a packed tower with 10 to 40 theoretical plates, and more preferably 15 to 25 theoretical plates.

[0026] The present invention discloses a product separation and purification device for the production of methyl formate via CO esterification. The MF separation tower is a packed tower, a plate tower, or a composite tower of packed and plate towers, preferably a packed tower, with 30-70 theoretical plates, more preferably 50-60 theoretical plates. The side stream outlet of the MF separation tower is located at the 3rd-15th plate from the top of the tower, preferably 5th-10th plate.

[0027] The present invention discloses a product separation and purification device for the production of methyl formate by CO esterification. The MF stripping column is a packed column, a plate column, or a composite column of packed and plate columns. It is preferred to use a packed column with 8 to 25 theoretical plates, and more preferably 10 to 20 theoretical plates.

[0028] The present invention discloses a product separation and purification device for the production of methyl formate by CO esterification. The MF purification tower is a packed tower, a plate tower, or a composite tower of packed tower and plate tower. It is preferred to use a packed tower with 40 to 80 theoretical plates, and more preferably 50 to 65 theoretical plates.

[0029] The present invention discloses a product separation and purification device for the production of methyl formate by CO esterification. The DMO distillation column is a packed column, a plate column, or a composite column of packed and plate columns. A packed column is preferred, with 8 to 25 theoretical plates, and more preferably 12 to 20 theoretical plates.

[0030] This invention provides a method for separating and purifying methyl formate produced by CO esterification, characterized by comprising the following steps:

[0031] 1) The product stream of CO esterification to produce methyl formate is cooled and condensed and then separated. The liquid phase obtained from the separation is sent to the DMO stripping tower for further separation. The gas phase obtained from the separation enters the methanol absorption tower. The DMO stripping tower separates the gas phase and the liquid phase containing DMO stream. The liquid phase containing DMO stream is sent to the hydrolysis unit or external distribution device. The gas phase separated from the DMO stripping tower enters the methanol absorption tower.

[0032] 2) In the methanol absorption tower, the gaseous stream entering the methanol absorption tower in step 1) is in countercurrent contact with one or more streams of absorbent entering from the top of the methanol absorption tower to carry out the absorption process. The rich absorbent liquid at the bottom of the methanol absorption tower is separated and distilled to obtain a light component, a solution rich in MF, and a solution containing DMO and methanol. The light component is mixed with the gas coming out from the top of the methanol absorption tower and used as a circulating gas. The solution rich in MF is purified to obtain MF product. The solution containing DMO and methanol is directly distilled to obtain DMO product and methanol stream. Alternatively, the solution containing DMO and methanol is divided into two parts, one part is returned to the top of the methanol absorption tower as absorbent, and the other part is distilled to obtain DMO product and methanol stream.

[0033] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification. The cooling, condensation and separation of the product stream from CO esterification is carried out by staged condensation and separation, resulting in two streams of condensate, which are respectively sent to the top and middle suitable positions of the DMO stripping tower according to their concentration differences.

[0034] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein the product stream of methyl formate produced by CO esterification is cooled and condensed and then separated into liquids, and the gas phase obtained from the separation enters the lower part of the methanol absorption tower; the gas phase separated from the DMO stripping tower enters the lower part of the methanol absorption tower.

[0035] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification. Preferably, in a methanol absorption tower, the rich absorbent from the bottom of the methanol absorption tower sequentially enters an MF separation tower and an MF stripping tower for separation and stripping. After separation and stripping, a light component, an MF-rich solution, and a solution containing DMO and methanol are obtained. The light component is mixed with the gas exiting from the top of the methanol absorption tower and used as a circulating gas. The MF-rich solution enters the MF purification tower for purification to obtain the MF product. The solution containing DMO and methanol directly enters the DMO distillation tower for distillation to obtain the DMO product and methanol stream. Alternatively, the solution containing DMO and methanol is divided into two parts: one part is returned to the methanol absorption tower as an absorbent, and the other part enters the DMO distillation tower for distillation to obtain the DMO product and methanol stream.

[0036] The present invention discloses a method for separating and purifying the product of CO esterification to produce methyl formate. Preferably, the solution containing DMO and methanol is divided into two parts: one part is returned to the upper part of the methanol absorption tower as an absorbent, and the other part is distilled to obtain DMO product and methanol stream.

[0037] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification. Further preferred, the rich absorbent from the bottom of the methanol absorption tower enters an MF separation tower for separation. A light component is obtained at the top of the MF separation tower, which is mixed with the gas exiting the top of the methanol absorption tower and used as a recycle gas. A solution containing DMO and methanol is obtained at the bottom of the MF separation tower. The liquid phase stream extracted from the side stream of the MF separation tower enters an MF stripping tower. After stripping in the MF stripping tower, an MF-rich solution and a gas phase are obtained. The MF-rich solution enters an MF purification tower for purification. The gas phase obtained after stripping in the MF stripping tower is returned to the MF separation tower.

[0038] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein methanol is preferably the absorbent in the methanol absorption tower.

[0039] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein the top temperature of the MF separation column is 0~15℃, preferably 5~10℃; and the bottom temperature is 100~130℃, preferably 110~120℃.

[0040] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein the bottom temperature of the MF stripping column is 65~95℃, preferably 75~90℃.

[0041] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein the top temperature of the MF purification column is 30~45℃, preferably 35~40℃; and the bottom temperature is 60~90℃, preferably 70~80℃.

[0042] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein the top temperature of the DMO distillation column is 40~60℃, preferably 45~55℃; and the bottom temperature is 140~200℃, preferably 160~185℃.

[0043] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein the product stream of methyl formate produced by CO esterification is cooled to 65~90℃ and then separated.

[0044] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein the top pressure of the DMO stripping column is 0.3~0.7 MPa, the top temperature is 90~130℃, and the bottom temperature is 180~220℃.

[0045] The refined methanol obtained from the methanol refining unit can be returned to the methanol absorption tower as an absorbent.

[0046] The function of the methanol absorption tower described in this invention is to absorb the MF and DMO in the reaction products of CO esterification to methyl formate into methanol using an absorbent (preferably methanol).

[0047] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification. Preferably, the methanol absorption tower has three streams as absorbents. From top to bottom along the methanol absorption tower, the absorbents are fresh methanol, recovered methanol from the unit, and a mixture containing methanol and DMO from the bottom of the MF separation tower.

[0048] The temperature range for each absorbent and the intermediate cooling temperature of the absorption tower is 0~40℃. The preferred temperature range is 5~20℃.

[0049] The main function of the MF refining column described in this invention is to refine MF to meet product requirements through distillation. The MF refining column is typically a distillation column, with a reboiler at the bottom and a cooler and condenser / liquid separator at the top.

[0050] The main function of the DMO distillation column described in this invention is to purify DMO to meet product requirements through distillation. The DMO distillation column is typically a distillation column with a reboiler at the bottom and a cooler and a total condensate separator at the top.

[0051] This invention can be used for the separation and purification of methyl formate product logistics, and is mainly used for the separation and purification of methyl formate produced by CO esterification.

[0052] Compared with the prior art, the product separation and purification apparatus and method for CO esterification to methyl formate described in this invention have the following advantages:

[0053] (1) The present invention pre-separates DMO through a condensation-distillation method, thereby reducing the amount of DMO processed in subsequent processes;

[0054] (2) In a preferred embodiment of the present invention, a portion of the DMO-methanol mixture at the bottom of the MF separator can be returned to the upper part of the methanol absorber as an absorbent, reducing the amount of fresh methanol used, thereby reducing the amount of methanol to be separated in subsequent processes and saving energy. Furthermore, using the recycled DMO-methanol mixture as an absorbent increases the DMO concentration in the DMO methanol solution at the bottom of the MF separator (DMO concentration), reducing the separation difficulty and energy consumption in the subsequent DMO distillation column. Additionally, by adjusting the DMO concentration in the DMO-methanol mixture at the bottom of the MF separator, the gas-liquid load in the DMO distillation column for both product schemes can be made closer, allowing the size of the DMO distillation equipment to better adapt to the two product schemes.

[0055] (3) In the preferred case of the methanol absorption tower of the present invention, three absorbents can be used, which are ① methanol, ② methanol recovered by the device, and ③ a mixture containing DMO and methanol from the bottom of the MF separation tower. This can reduce the amount of fresh methanol used, save the raw materials of the device, reduce the amount of methanol processed in the subsequent process, and thus save energy.

[0056] (4) The present invention connects the MF separation tower and the MF stripping tower, and adopts the form of combining the main body of the distillation tower and the side stripping tower to replace the conventional two distillation towers, saving the cooler, reflux tank, pump, pipeline instrument and other equipment of the second distillation tower, thus saving investment and land area.

[0057] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this does not limit the scope of the invention. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of a product separation and purification apparatus for the CO esterification of methyl formate according to the present invention.

[0059] The reference numerals in the figure are:

[0060] 1-MF product feed line, 2-reaction product separator, 3-DMO stripping tower, 4-methanol absorption tower, 5-MF separation tower, 6-MF stripping tower, 7-DMO rectification tower, 8-MF refining tower, 9-fresh methanol inlet, 10-recovered methanol inlet, 11-circulating methanol inlet, 12-circulating gas extraction outlet, 13-upper inlet of MF separation tower, 14-side stream outlet, 15-gas outlet of MF separation tower, 16-MF product outlet.

[0061] like Figure 1 As shown, this invention discloses a product separation and purification apparatus for the production of methyl formate via CO esterification. The apparatus includes a reaction product separator 2, a DMO stripping column 3, a methanol absorption column 4, an MF separation column 5, an MF stripping column 6, an MF purification column 8, and a DMO rectification column 7. An MF product feed line 1 is connected to the inlet of the reaction product separator 2. The bottom outlet of the reaction product separator 2 is connected to the upper inlet of the DMO stripping column 3. The top outlet of the reaction product separator 2 is connected to the lower inlet of the methanol absorption column 4. The top outlet of the DMO stripping column 3 is connected to the lower inlet of the methanol absorption column 4. One or more (more than two) absorbent inlets are sequentially arranged from top to bottom on the upper part of the methanol absorption column 4. A circulating gas outlet 12 is provided at the top of the methanol absorption column 4. The bottom outlet of column 4 is connected to the middle inlet of column 5. Column 5 has a gas outlet 15 at the top. The bottom outlet of column 5 is connected to the middle inlet of column 7, or to the middle inlet of column 7 and the upper absorbent inlet of column 4, respectively. Column 5 has a side outlet at the top, which is connected to the upper inlet of column 6. The top outlet of column 6 is connected to the upper inlet of column 5. The bottom outlet of column 6 is connected to the upper inlet of column 8. Column 8 has a top MF product extraction outlet 16 and a bottom outlet. Column 7 has a bottom DMO stream outlet and a top outlet.

[0062] In this invention, the bottom outlet of the MF separation tower 5 is preferably connected to the middle inlet of the DMO distillation tower 7 and the upper absorbent inlet of the methanol absorption tower 4, respectively (this is the case shown in the figure).

[0063] The upper inlet position 13 of the MF separation tower described in this invention is located above the upper side outlet 14 of the MF separation tower.

[0064] In this invention, the methanol absorption tower 4 preferably has three absorbent inlets arranged sequentially from top to bottom on the upper part.

[0065] The methanol absorption tower 4 of this invention is a packed tower, a plate tower, or a composite tower of packed and plate structures, preferably a packed tower, with 10-40 theoretical plates, more preferably 15-25 theoretical plates. The MF separation tower 5 is a packed tower, a plate tower, or a composite tower of packed and plate structures, preferably a packed tower, with 30-70 theoretical plates, more preferably 50-60 theoretical plates. The side stream outlet of the MF separation tower is located 3-15 plates from the top of the tower, preferably 5-10 plates. The MF stripping tower 6 is a packed tower, a plate tower, or a composite tower of packed and plate structures, preferably a packed tower, with 8-25 theoretical plates, more preferably 10-20 theoretical plates. The MF refining tower 8 is a packed tower, a plate tower, or a composite tower of packed and plate structures, preferably a packed tower, with 40-80 theoretical plates, more preferably 50-65 theoretical plates. The DMO distillation column 7 is a packed column, a plate column, or a composite column of packed and plate columns, preferably a packed column, with 8 to 25 theoretical plates, preferably 12 to 20 theoretical plates.

[0066] Unless otherwise specified, the distillation column in the apparatus of this invention refers to the distillation column system, including the distillation column body and auxiliary equipment such as the bottom reboiler, the bottom product transfer pump, the top condenser, the top reflux tank, and the top reflux and product transfer pump.

[0067] The simple steps of the CO esterification to methyl formate product separation and purification method described in this invention are as follows:

[0068] 1) The product stream of CO esterification to produce methyl formate is cooled and condensed and then separated into liquids. The separated liquid phase is sent to DMO stripping tower 3 for further separation. The gas phase separated from DMO stripping tower 3 is mixed with the gas phase separated from reaction product separator 2 and then enters the lower part of methanol absorption tower 4. The DMO stream separated from DMO stripping tower 3 can be sent to the hydrolysis unit or external delivery device.

[0069] 2) In methanol absorption tower 4, the gaseous stream entering the lower part of methanol absorption tower 4 in step 1) undergoes countercurrent contact with the absorbent entering the upper part of methanol absorption tower 4 for absorption. The rich absorbent at the bottom of methanol absorption tower sequentially enters MF separation tower 5 and MF stripping tower 6 for separation and stripping. After separation and stripping, a solution containing light components, MF-rich solution, DMO, and methanol is obtained. The light components are mixed with the gas exiting from the top of methanol absorption tower and used as circulating gas. The MF-rich solution enters MF purification tower 8 for purification to obtain MF product. The solution containing DMO and methanol directly enters DMO distillation tower 7 for distillation to obtain DMO product and methanol stream. Alternatively, the solution containing DMO and methanol is divided into two parts: one part is returned to methanol absorption tower 4 as absorbent, and the other part enters DMO distillation tower for distillation to obtain DMO product and methanol stream. Figure 1The solution containing DMO and methanol is divided into two parts. One part is returned to methanol absorption tower 4 as an absorbent, and the other part enters the DMO distillation tower for distillation to obtain DMO product and methanol stream.

[0070] The solution containing DMO and methanol is obtained at the bottom of the MF separation tower. The liquid phase stream is drawn from the side stream of the MF separation tower 5 and enters the MF stripping tower 6. After stripping in the MF stripping tower 6, a solution rich in MF and a gas phase are obtained. The solution rich in MF enters the MF purification tower 8 for purification. The gas phase obtained after stripping in the MF stripping tower is returned to the MF separation tower 5.

[0071] The cooling, condensation, and separation of the product stream from CO esterification to methyl formate described in this invention can be achieved by staged condensation and separation, resulting in two streams of condensate that enter the top and middle sections of the distillation tower respectively, based on their concentration differences.

[0072] Methanol is preferably the absorbent in the methanol absorption tower 4 of the present invention.

[0073] The MF separation column 5 of this invention has a top temperature of 0~15℃, preferably 5~10℃, and a bottom temperature of 100~130℃, preferably 110~120℃; the MF stripping column 6 has a bottom temperature of 65~95℃, preferably 75~90℃; the MF refining column 8 has a top temperature of 30~45℃, preferably 35~40℃, and a bottom temperature of 60~90℃, preferably 70~80℃; the DMO distillation column 7 has a top temperature of 40~60℃, preferably 45~55℃, and a bottom temperature of 140~200℃, preferably 160~185℃; the product stream from CO esterification to methyl formate is cooled to 65~90℃ and then separated; the DMO stripping column 3 has a top pressure of 0.3~0.7MPag, a top temperature of 90~130℃, and a bottom temperature of 180~220℃.

[0074] The refined methanol obtained from the methanol refining unit described in this invention can be returned to the methanol absorption tower 4 as an absorbent.

[0075] The function of the methanol absorption tower 4 described in this invention is to absorb the MF and DMO in the reaction products of CO esterification to methyl formate into methanol using an absorbent (preferably methanol).

[0076] The present invention discloses a method for separating and purifying methyl formate produced by CO esterification, wherein the methanol absorption tower 4 preferably has 3 streams as absorbent. Figure 1 The diagram shows three streams acting as absorbents. From top to bottom along the methanol absorption tower 4, these are fresh methanol, recovered methanol from within the unit, and a mixture containing methanol and DMO from the bottom of the MF separation tower 5.

[0077] The temperature range of each absorbent in the methanol absorption tower and the intermediate cooling temperature range of the absorption tower are 0~40℃. The preferred temperature range is 5~20℃.

[0078] The main function of the MF refining column 8 described in this invention is to refine MF to meet product requirements through distillation. The MF refining column 8 is typically a distillation column, with a reboiler at the bottom and a cooler and condenser / liquid separator at the top.

[0079] The main function of the DMO distillation column 7 described in this invention is to purify DMO to meet product requirements through distillation. The DMO distillation column 7 is typically a distillation column with a reboiler at the bottom and a cooler and a total condensate separator at the top.

[0080] This invention can be used for the separation and purification of methyl formate product logistics, and is mainly used for the separation and purification of methyl formate produced by CO esterification.

Claims

1. A product separation and purification apparatus for the production of methyl formate by the esterification of CO, characterized by: The product separation and purification device for preparing methyl formate by CO esterification comprises a reaction product separation tank, a DMO distillation column, a methanol absorption column, an MF separation column, an MF distillation column, an MF purification column and a DMO rectification column, an MF product feeding pipeline is connected with the inlet of the reaction product separation tank, the bottom outlet of the reaction product separation tank is connected with the upper inlet of the DMO distillation column, the top outlet of the reaction product separation tank is connected with the lower inlet of the methanol absorption column, the top outlet of the DMO distillation column is connected with the lower inlet of the methanol absorption column, one or more absorption agent inlets are arranged on the upper portion of the methanol absorption column, a circulating gas outlet is arranged on the top of the methanol absorption column, the bottom outlet of the methanol absorption column is connected with the middle inlet of the MF separation column, the top of the MF separation column is provided with an MF separation column gas outlet, the bottom outlet of the MF separation column is connected with the middle inlet of the DMO rectification column, or is connected with the inlet of the DMO rectification column and the upper absorption agent inlet of the methanol absorption column respectively, the upper portion of the MF separation column is provided with a side outlet, the side outlet is connected with the upper inlet of the MF distillation column, the top outlet of the MF distillation column is connected with the upper inlet of the MF separation column, the bottom outlet of the MF distillation column is connected with the middle-upper inlet of the MF purification column, the MF purification column is provided with an MF product outlet on the top and an MF purification column bottom outlet on the bottom, the DMO rectification column is provided with a DMO stream outlet on the bottom and a top outlet, and the upper inlet of the MF separation column is located above the side outlet of the upper portion of the MF separation column.

2. A product separation and purification apparatus for the production of methyl formate by CO esterification according to claim 1, characterized in that: The bottom outlet of the MF separation column is connected with the middle inlet of the DMO rectification column and the upper absorption agent inlet of the methanol absorption column respectively.

3. A product separation and purification apparatus for the production of methyl formate by CO esterification according to claim 1, characterized in that: Three absorption agent inlets are sequentially arranged on the upper portion of the methanol absorption column from top to bottom.

4. A product separation and purification apparatus for the production of methyl formate by CO esterification according to claim 1, characterized in that: The methanol absorption column, the MF separation column, the MF distillation column, the MF purification column and the DMO rectification column are all packed columns, or plate columns, or packed and plate composite columns.

5. A product separation and purification apparatus for the production of methyl formate by CO esterification according to claim 4, characterized in that: The methanol absorption column is provided with 10-40 theoretical plates, the MF separation column is provided with 30-70 theoretical plates, the side outlet of the MF separation column is located at the third to fifteenth theoretical plate from the top of the column, the MF distillation column is provided with 8-25 theoretical plates, the MF purification column is provided with 40-80 theoretical plates, and the DMO rectification column is provided with 8-25 theoretical plates.

6. A product separation and purification apparatus for the production of methyl formate by CO esterification according to claim 5, characterized in that: The methanol absorption column is provided with 15-25 theoretical plates, the MF separation column is provided with 50-60 theoretical plates, the side outlet of the MF separation column is located at the fifth to tenth plate from the top of the column, the MF distillation column is provided with 10-20 theoretical plates, the MF purification column is provided with 50-65 theoretical plates, and the DMO rectification column is provided with 12-20 theoretical plates.

7. The process for the separation and purification of the products of the methoxylation of CO according to claim 1, characterized in that The method comprises the following steps: 1) a product stream prepared by CO esterification is cooled and condensed, then separated, the liquid phase obtained by separation is sent to a DMO distillation column for further separation, the gas phase obtained by separation is sent to the lower portion of a methanol absorption column, the DMO distillation column separates a gas phase and a liquid phase containing a DMO stream, the liquid phase containing the DMO stream is sent to a hydrolysis unit, and the gas phase separated by the DMO distillation column is sent to the lower portion of the methanol absorption column; 2) in the methanol absorption tower, the gas phase stream of step 1) is absorbed by countercurrently contacting with one or more absorption agents entering the upper part of the methanol absorption tower, the rich absorption liquid at the bottom of the methanol absorption tower is separated in the MF separation tower, the light component at the top of the MF separation tower is mixed with the gas at the top of the methanol absorption tower and used as the circulating gas, the solution containing DMO and methanol at the bottom of the MF separation tower is directly introduced into the DMO rectification tower to obtain the DMO product and the methanol stream, or the solution containing DMO and methanol is divided into two parts, one part is returned to the methanol absorption tower as the absorption agent, and the other part is introduced into the DMO rectification tower to obtain the DMO product and the methanol stream.

8. The method of claim 7, wherein: The solution containing DMO and methanol is divided into two parts, one part is returned to the upper part of the methanol absorption tower as the absorption agent, and the other part is rectified to obtain the DMO product and the methanol stream.

9. The method of claim 7, wherein: The top temperature of the MF separation tower is 0-15℃, and the bottom temperature is 100-130℃; the bottom temperature of the MF stripping tower is 65-95℃; the top temperature of the MF refining tower is 30-45℃, and the bottom temperature is 60-90℃; the top temperature of the DMO rectification tower is 40-60℃, and the bottom temperature is 140-200℃; the top pressure of the DMO stripping tower is 0.3-0.7 MPag, and the top temperature is 90-130℃.

10. The method of claim 9, wherein: The top temperature of the MF separation tower is 5-10℃, and the bottom temperature is 110-120℃; the bottom temperature of the MF stripping tower is 75-90℃; the top temperature of the MF refining tower is 35-40℃, and the bottom temperature is 70-80℃; the top temperature of the DMO rectification tower is 45-55℃, and the bottom temperature is 160-185℃.

11. The method of claim 7, wherein: The product stream of the CO esterification to prepare methyl formate is cooled to 65-90℃ and then separated.

12. The method of claim 7, wherein: Three absorption agents are introduced into the upper part of the methanol absorption tower.

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