Continuous reaction apparatus for esterification and method for continuous synthesis of esters

Abstract

The present application relates to the technical field of process intensification, and discloses an esterification continuous reaction device and a continuous synthesis method of ester, which comprises an oil phase reaction module, a water phase module and an oil-water separation section, liquid phase raw materials are subjected to cyclone type high-efficiency mixing in the microchannel of the mixing area of the oil phase reaction module, high-efficiency reaction and separation are carried out in the oil phase reaction channel of the first reaction area and the second reaction area, and the target product can be obtained after mixing-reaction-separation, the reaction device provided by the present application realizes precise reaction between materials by using process intensification technology, greatly improves the atomic economy and space utilization of the process, and simultaneously develops a mixed reaction channel with a micro-grid mixing structure and a second reaction area with an in-situ oil-water separation function for a liquid-liquid heterogeneous reaction system, so that the high-efficiency mixing-reaction-separation efficiency and continuous production of high-purity products in the whole process can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of process intensification, in particular to an esterification continuous reaction device and a continuous synthesis method of ester. BACKGROUND

[0002] Methyl mercaptoacetate is an important fine chemical product, one of mercaptoacetic acid series derivatives, and an important intermediate for the synthesis of pesticides, medicines, tobacco flavorants and food flavorants. In the field of pesticides, methyl mercaptoacetate is an intermediate for the synthesis of pesticide thiophene sulfonate; in the field of medicine, methyl mercaptoacetate can be used for the synthesis of hydrochloric acid atikain and non-steroidal anti-inflammatory drug intermediate 5-chloro-2-carboxylic acid methyl ester-3-methylamine sulfonamide thiophene. Methyl mercaptoacetate can also be used to synthesize plastic heat stabilizers, such as PVC organic tin heat stabilizers, etc.

[0003] At present, the production and synthesis method of methyl mercaptoacetate mainly uses mercaptoacetic acid and methanol as raw materials, supplemented with catalysts to prepare. At present, concentrated sulfuric acid is usually used as a catalyst in industrial production, which is cheap and easy to obtain, and has high catalytic efficiency, but it has serious environmental pollution and safety hazards. In terms of methyl mercaptoacetate synthesis technology: China began to study the synthesis method of methyl mercaptoacetate and its derivatives in the 1970s, the research is relatively lagging behind, the production process is relatively backward, and the environmental pollution is serious. And the price of raw material mercaptoacetic acid is high, and part of it depends on import, resulting in high production cost. At present, most of the high-purity methyl mercaptoacetate in China depends on import, and the number of domestic production enterprises is small. The large-scale enterprises in the industry include Zhengzhou Yin Yue Chemical Co., Ltd., Shandong Xinchang Chemical Technology Co., Ltd., Qingdao Jiahua Chemical Co., Ltd., etc. In view of the defects in product yield, reaction raw material recovery and other aspects of the domestic methyl mercaptoacetate production process, the relevant enterprises in China have strengthened the research work in this field.

[0004] CN101580485 proposes a synthesis process of methyl mercaptoacetate, which uses p-toluenesulfonic acid as an activator to improve the catalytic efficiency, and realizes the improvement of product yield and purity. However, this method still has obvious shortcomings: first, it uses batch kettle process for production, and the product quality between batches is uncontrollable; second, the catalyst uses sulfuric acid, and the introduction of p-toluenesulfonic acid as an additive increases the safety hazard and environmental pollution of the system; finally, in order to obtain high-purity methyl mercaptoacetate product, a complex separation and purification process is needed, the process flow is long, and the equipment cost and operation cost are high. SUMMARY

[0005] In order to solve the problems of uncontrollable product quality, safety hazards and environmental pollution in the existing technology of methyl mercaptoacetate synthesis process, the present application provides an esterification continuous reaction device and a continuous synthesis method of ester, which can greatly improve the reaction efficiency and product quality and is green, environmentally friendly and safe in the whole process.

[0006] To achieve the above object, the first aspect of the present application provides an esterification continuous reaction device, which comprises: an oil phase reaction module, the oil phase reaction module has a mixing zone, a first reaction zone and a second reaction zone connected in series along the material flow direction, the second reaction zone is provided with an oil phase product outlet, the first reaction zone and the second reaction zone comprise an oil phase reaction channel in communication; a water phase module arranged below the oil phase reaction module, part of the water phase module has a water phase product groove and a water phase product outlet arranged at one end of the water phase product groove for leading out the water phase product; and a partition plate arranged between the oil phase reaction module and the water phase module, the partition plate comprises an oil-water separation section, the oil-water separation section is used for oil-water separation of the reaction material of the oil phase reaction channel of the second reaction zone, the separated water phase flows into the water phase product groove, and the oil phase flows out from the oil phase product outlet; the mixing zone has a mixing channel, the mixing channel is in communication with the oil phase reaction channel, and the oil phase reaction channel is connected with the oil phase product outlet, wherein the mixing channel comprises an organic alcohol raw material inlet and an organic acid raw material inlet arranged in parallel, so that the organic alcohol raw material and the organic acid raw material are mixed in the mixing zone and then enter the first reaction zone and the second reaction zone in sequence for esterification reaction.

[0007] The second aspect of the present application provides a continuous synthesis method of ester, which is implemented by the esterification continuous reaction device of the present application, and the method comprises the following steps:

[0008] 1) The organic alcohol raw material flows into the whole device through the organic alcohol raw material inlet as a medium and raises the reaction environment in the device to a specified reaction temperature and pressure;

[0009] 2) The organic acid raw material enters the mixing channel from the organic acid raw material inlet according to the required proportion, is mixed with the organic alcohol raw material, and then enters the oil phase reaction channel of the first reaction zone to perform preliminary esterification reaction under the first reaction condition, and then enters the second reaction zone to perform deep esterification reaction under the second reaction condition, so as to obtain a mixed reaction product;

[0010] 3) The water phase product in the mixed reaction product of step 3) is separated in situ by the oil-water separation section, so as to promote the forward progress of the esterification reaction;

[0011] Wherein, the oil phase product remains in the oil phase reaction channel, the water phase product enters the water phase product groove, and the oil phase product and the water phase product are collected at the oil phase product outlet and the water phase product outlet respectively.

[0012] Compared with the prior art, the continuous channel reaction device provided by the application realizes the intensification of the mixing-reaction-separation process by coupling the microscale mixing structure with the nanoscale microfilm structure, realizes the precise control of the material mixing-reaction-separation by the microchannel technology and the membrane separation technology, and greatly improves the reaction efficiency and product quality.

[0013] The method for continuously synthesizing ester provided by the application realizes the continuous production of ester synthesized by using organic alcohol and organic acid as raw materials, guarantees the quality stability of the product, greatly reduces the traditional process flow, has high atom economy, is green and environmentally friendly in the whole process, and greatly reduces the equipment, environmental protection and safety costs.

[0014] In addition, the reaction device and method provided by the application are particularly suitable for the synthesis of methyl mercaptoacetate, have obvious advantages in energy consumption and material consumption compared with the prior art, and can greatly reduce the fixed investment and labor cost.

[0015] Other features and advantages of the application will be described in detail in the following specific embodiment part. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The figure is a schematic diagram of the overall structure of the esterification continuous reaction device of a preferred embodiment of the application.

[0017] Figure 2 The figure is a schematic diagram of the structure of the oil phase reaction module of a preferred embodiment of the application.

[0018] Figure 3 The figure is a schematic diagram of the structure of the water phase module of a preferred embodiment of the application.

[0019] Figure 4 The figure is a schematic diagram of the microgrid structure of a preferred embodiment of the application.

[0020] BRIEF DESCRIPTION OF DRAWINGS

[0021] 1 organic alcohol raw material inlet; 2 organic acid raw material inlet;

[0022] 3 oil phase reaction module; 4 partition plate;

[0023] 41 oil-water separation section; 5 water phase module;

[0024] 6 oil phase product outlet; 7 water phase product outlet;

[0025] 8 mixing channel; 9 oil phase reaction channel;

[0026] 10 mixing zone; 11 first reaction zone;

[0027] 12 second reaction zone; 13 microgrid;

[0028] 14 aqueous phase product groove. DETAILED DESCRIPTION

[0029] The specific embodiments of the present application will be described in detail in the following. Figures 1-4 It should be understood that the specific embodiments described herein are merely illustrative and explanatory in nature and are not restrictive to the present application.

[0030] In the present application, the orientation words such as "up, down, left, right" used without the contrary description are generally understood in connection with the orientation shown in the drawings and the actual application. "Inner, outer" refers to the inner and outer relative to the outline of each component itself. The hydraulic diameter in the present application refers to four times the ratio of the flow area to the circumference, which is commonly used in the calculation of pipe resistance in chemical equipment.

[0031] As shown in Figures 1-4 The first aspect of the present application provides an esterification continuous reaction device, which comprises: an oil phase reaction module 3, the oil phase reaction module 3 has a mixing zone 10, a first reaction zone 11 and a second reaction zone 12 connected in series along the material flow direction, the second reaction zone 12 is provided with an oil phase product outlet 6, and the first reaction zone 11 and the second reaction zone 12 comprise an oil phase reaction channel 9 in communication; a water phase module 5 arranged below the oil phase reaction module 3, part of the water phase module 5 has an aqueous phase product groove 14 and a water phase product outlet 7 arranged at one end of the aqueous phase product groove 14 for leading out the aqueous phase product; and a partition plate 4 arranged between the oil phase reaction module 3 and the water phase module 5, the partition plate 4 comprises an oil-water separation section 41 for separating the reaction material of the oil phase reaction channel 9 of the second reaction zone 12 into oil phase and water phase, the separated aqueous phase flows into the aqueous phase product groove 14, and the oil phase flows out from the oil phase product outlet 6; the mixing zone 10 has a mixing channel 8 in communication with the oil phase reaction channel 9, and the oil phase reaction channel 9 is connected with the oil phase product outlet 6;

[0032] The mixing channel 8 comprises an organic alcohol raw material inlet 1 and an organic acid raw material inlet 2 arranged in parallel, so that the organic alcohol raw material and the organic acid raw material are mixed in the mixing zone 10 and then enter the first reaction zone 11 and the second reaction zone 12 in sequence for esterification reaction, wherein preliminary esterification is carried out in the first reaction zone 11, deep esterification and continuous phase separation of the aqueous phase product generated during the reaction are carried out in the second reaction zone 12.

[0033] In the present application, the oil phase reaction module 3, the partition plate 4 and the water phase module 5 are three plates stacked in the height direction, wherein the mixing channel 8 and the oil phase reaction channel 9 are in communication to form a continuous channel.

[0034] The present application can use perfluorinated rubber rings to seal the interfaces of each unit or component, which is a well-known technology in the art and will not be described in detail herein.

[0035] According to a preferred embodiment of the present application, the oil phase reaction channel 9 in the second reaction zone 12 has a radial opening corresponding to the water phase product groove 14, and the oil-water separation section 41 is formed in the partition region between the oil phase channel 9 and the opening of the water phase product groove 14.

[0036] According to a preferred embodiment of the present application, the hydrodynamic diameters of the organic acid raw material inlet 2 and the organic alcohol raw material inlet 1 are 500-2000 μm, preferably 800-1000 μm.

[0037] According to a preferred embodiment of the present application, the thicknesses of the oil phase reaction module 3 and the water phase module 5 are each 1-5 cm.

[0038] According to a preferred embodiment of the present application, the thicknesses of the oil phase reaction module 3 and the water phase module 5 are the same.

[0039] According to a preferred embodiment of the present application, the thickness of the partition 4 is 0.1-1 cm.

[0040] According to a preferred embodiment of the present application, the oil phase reaction channel 9 of the second reaction zone 12 is consistent in shape with the water phase product groove 14, so that the oil-water two-phase is separated in situ and the esterification reaction in the oil phase reaction channel 9 is promoted to proceed in the forward direction, and the present application uses process intensification technology to realize precise reaction between materials, ensure continuous production of high-purity products, and greatly improve the atom economy and space utilization of the process.

[0041] According to a preferred embodiment of the present application, as shown in Figure 1 The micro-grid 13 has a slit, and a plurality of micro-grids 13 are arrayed along the material flow direction to form a micro-grid mixing structure, so that the liquid-liquid heterogeneous reaction system can be subjected to high-efficiency mixing in the form of cyclone.

[0042] According to a preferred embodiment of the present application, preferably, the slit width of the micro-grid 13 is 10-100 μm, more preferably 40-60 μm.

[0043] According to a preferred embodiment of the present application, preferably, the slit spacing of the micro-grid 13 is 10-100 μm, more preferably 40-60 μm.

[0044] According to a preferred embodiment of the present application, as shown in Figure 4As shown, the distance between two adjacent micro-grids 13 is 1-5 cm, preferably the projection of the slits of two adjacent micro-grids 13 in the direction of the material flow has an included angle, preferably the included angle is 10-60°, more preferably 20-50°.

[0045] According to the preferred embodiment of the present application, as Figure 2 As shown, the mixing channel 8 and / or the oil phase reaction channel 9 is arranged in a "se" shape in the oil phase reaction module 3.

[0046] According to the preferred embodiment of the present application, preferably, the hydraulic diameter of the mixing channel 8 is the same as the hydraulic diameter of the oil phase reaction channel 9, more preferably the hydraulic diameter is 100-2000 μm, further preferably 300-1500 μm.

[0047] According to the preferred embodiment of the present application, the hydraulic diameter of the aqueous phase product groove 14 is 100-5000 μm, preferably 200-3000 μm.

[0048] According to the preferred embodiment of the present application, the liquid holdup of the mixing zone 10 is 5-50 ml, preferably 10-40 ml.

[0049] According to the preferred embodiment of the present application, the liquid holdup of the first reaction zone 11 is 10-100 ml, preferably 30-60 ml.

[0050] According to the preferred embodiment of the present application, the liquid holdup of the second reaction 12 is 50-200 ml, preferably 80-150 ml.

[0051] According to the preferred embodiment of the present application, the hydraulic diameter of the oil phase product outlet 6 is 1-10 mm, and the hydraulic diameter of the aqueous phase product outlet 7 is 1-10 mm.

[0052] According to the preferred embodiment of the present application, the oil-water separation section 4 comprises a separation membrane selected from one of an organic membrane, an inorganic membrane or a composite membrane.

[0053] According to the preferred embodiment of the present application, preferably, the membrane pore diameter of the separation membrane is 100-1000 nm.

[0054] The present application provides a continuous synthesis method of ester, which is implemented by the esterification continuous reaction device of the present application, comprising the following steps:

[0055] 1) flowing the organic alcohol raw material into the whole device as a medium from the organic alcohol raw material inlet 1 and raising the reaction environment in the device to the specified reaction temperature and pressure;

[0056] 2) The organic acid raw material is mixed with the organic alcohol raw material at the mixing channel 8 according to the required proportion, and then enters the oil phase reaction channel 9 of the first reaction zone 11 to perform a preliminary esterification reaction under the first reaction condition, and then enters the second reaction zone 12 to perform a deep esterification reaction under the second reaction condition, to obtain a mixed reaction product;

[0057] 3) The water phase product in the mixed reaction product in step 3) is separated in situ by the oil-water separation section 13, to promote the forward progress of the esterification reaction;

[0058] Wherein, the oil phase product remains in the oil phase reaction channel 9, and the water phase product enters the water phase product groove 14, and the oil phase product and the water phase product are collected at the oil phase product outlet 6 and the water phase product outlet 7 respectively. It should be noted that the oil-water separation section 41 adopts a ceramic membrane, uses a ceramic porous material as a substrate, and is subjected to a hydrophilic and oleophobic surface treatment, so that it can realize high-efficiency in-situ oil-water separation.

[0059] According to the preferred embodiment of the present application, the organic alcohol is one or more of methanol, ethanol, isopropyl alcohol and n-propyl alcohol.

[0060] According to the preferred embodiment of the present application, the organic acid is one or more of formic acid, acetic acid, mercaptoacetic acid and propionic acid.

[0061] According to the preferred embodiment of the present application, the preliminary esterification reaction in the first reaction zone 11 is ended when the conversion rate of the organic acid reaches 10-40%;

[0062] The first reaction condition of the preliminary esterification in the first reaction zone 11 includes: reaction temperature 40-60℃, residence time 5-10min.

[0063] The second reaction condition of the deep esterification in the second reaction zone 12 includes: reaction temperature 50-80℃, residence time 10-20min.

[0064] The device and method of the present application are further illustrated by the following examples and comparative examples, but the device and method of the present application are not limited to this.

[0065] The device and method of the present application are further illustrated by the following examples.

[0066] Example 1

[0067] (1) The device is built according to the following figure: Figures 1-3

[0068] ​The oil phase reaction module 3, the water phase module 5 and the partition 4 are made of stainless steel 316L, wherein the thickness of the oil phase reaction module 3 and the water phase module 5 is 2 cm, the thickness of the partition 4 is 0.5 cm, the three are laminated and compacted, the interfaces are sealed by using perfluorinated rubber rings, and the mixed channel 8 and the oil phase reaction channel 9 are connected to form a continuous channel reactor after being fastened.

[0069] The hydraulic diameters of the organic alcohol raw material inlet 1 and the organic acid raw material inlet 2 in the oil phase reaction module 3 are both set to 1000 μm, the holdup of the mixing zone 10 is 15 ml, the hydraulic diameter of the mixed channel 8 is 800 μm, the holdups of the first reaction zone 11 and the second reaction zone 12 are 50 ml and 100 ml respectively, the hydraulic diameter of the oil phase reaction channel 9 is 800 μm, the hydraulic diameter of the oil phase product outlet 6 is 5 mm, the hydraulic diameter of the water phase product outlet 7 is 5 mm, and the hydraulic diameter of the water phase product groove 14 is 1000 μm.

[0070] The mixed channel 8 is embedded with a micro-grid mixing structure formed by a plurality of micro-grids 13, the micro-grid mixing structure is composed of a slit array precisely processed by laser, the slit width is 50 μm, the slit pitch is 100 μm, the projection angle of the slits of adjacent two micro-grids 13 in the material flow direction is 45°, and the pitch between adjacent two micro-grids 13 is 2 cm.

[0071] The separation membrane in the oil-water separation section 41 adopts a ceramic membrane, uses a ceramic porous material as a substrate, and is subjected to hydrophilic and oleophobic surface treatment, so that it can realize efficient in-situ oil-water separation, wherein the membrane hole diameter of the ceramic membrane is 500 nm.

[0072] (2) Synthesis of methyl mercaptoacetate:

[0073] Methanol raw material is input from the organic alcohol raw material inlet 1 and fills the entire device, the reaction environment in the device is raised to the specified reaction temperature and pressure, and the methanol circulates between the zones and is controlled to the required flow by a mass flow meter. Methyl mercaptoacetate containing 0.5% p-toluenesulfonic acid is input from the organic acid raw material inlet 2 into the oil phase reaction module 3, is subjected to efficient mixing by the micro-grid mixing structure, is subjected to preliminary esterification reaction in the oil phase reaction channel 9 of the first reaction zone 11, then enters the second reaction zone 12 to promote the esterification reaction in the oil phase reaction channel 9, and the generated water phase product enters the water phase product groove 14 through the oil-water separation section 41, finally the products are collected from the water phase product outlet 7 and the oil phase product outlet 6 respectively, and methyl mercaptoacetate is the main component of the oil phase product. According to liquid chromatography analysis, the yield of methyl mercaptoacetate is 95.1% and the selectivity of methyl mercaptoacetate is greater than 98.7% during the reaction.

[0074] When the conversion rate of the organic acid reaches 31.3%, the preliminary esterification reaction in the first reaction zone 11 is terminated.

[0075] The first reaction conditions for the preliminary esterification in the first reaction zone 11 include: a reaction temperature of 60°C and a residence time of 5 min;

[0076] The second reaction conditions for deep esterification in the second reaction zone 12 include: a reaction temperature of 80°C and a residence time of 10 min.

[0077] Example 2

[0078] (1) According to Figures 1-3 The device is set up as shown:

[0079] The oil phase reaction module 3, the water phase module 5, and the partition plate 4 are made of 316L stainless steel. The oil phase reaction module 3 and the water phase module 5 are 2cm thick, and the partition plate 4 is 0.5cm thick. The three are stacked and compacted, and the interfaces are sealed with perfluororubber rings. After tightening, the mixing channel 8 and the oil phase reaction channel 9 are connected to form a continuous channel reactor.

[0080] In the oil phase reaction module 3, the hydraulic diameters of the organic alcohol raw material inlet 1 and the organic acid raw material inlet 2 are both set to 1000 μm. The liquid holding capacity of the mixing zone 10 is 15 ml, and the hydraulic diameter of the mixing channel 8 is 1200 μm. The liquid holding capacities of the first reaction zone 11 and the second reaction zone 12 are 50 ml and 100 ml, respectively. The hydraulic diameter of the oil phase reaction channel 9 is 1200 μm. The hydraulic diameter of the oil phase product outlet 6 is 5 mm, the hydraulic diameter of the aqueous phase product outlet 7 is 5 mm, and the hydraulic diameter of the aqueous phase product groove 14 is 1000 μm.

[0081] The mixing channel 8 is embedded with a micro-grid mixing structure formed by multiple micro-grids 13. The micro-grid mixing structure is composed of a laser-precision-machined slit array with a slit width of 50μm, a slit spacing of 100μm, a projection angle of 45° between the slits of two adjacent micro-grids 13 in the material flow direction, and a spacing of 2cm between two adjacent micro-grids 13.

[0082] The separation membrane in the oil-water separation section 41 is a ceramic membrane. It uses a porous ceramic material as a substrate and has undergone hydrophilic and oleophobic surface treatment to enable efficient in-situ oil-water separation. The pore diameter of the ceramic membrane is 500 nm.

[0083] (2) Synthesis of methyl mercaptoacetate:

[0084] The methanol raw material is input as a medium from the organic alcohol raw material inlet 1 and fills the entire device, the reaction environment in the device is raised to the specified reaction temperature and pressure, the methanol circulates between the zones and the flow is controlled to the required flow by the mass flow meter. The mercaptoacetic acid containing 0.5% p-toluene sulfonic acid is input into the oil phase reaction module 3 from the organic acid raw material inlet 2, high-efficiency mixing is performed by the micro-grid mixing structure, and then the preliminary esterification reaction is performed in the oil phase reaction channel 9 of the first reaction zone 11. The generated water phase product enters the water phase product groove 14 through the oil-water separation section 41, and finally the products are collected from the water phase product outlet 7 and the oil phase product outlet 6 respectively, and the methyl mercaptoacetate is the main component of the oil phase product. Through liquid chromatography analysis, the yield of methyl mercaptoacetate is 93.1% and the selectivity of methyl mercaptoacetate is 98.9% during the reaction process.

[0085] When the conversion rate of the organic acid reaches 29.8%, the preliminary esterification reaction in the first reaction zone 11 is ended;

[0086] The first reaction conditions of the preliminary esterification in the first reaction zone 11 include: reaction temperature 60℃, residence time 5min;

[0087] The second reaction conditions of the deep esterification in the second reaction zone 12 include: reaction temperature 80℃, residence time 10min.

[0088] Example 3

[0089] (1) The device is built as shown in the following figure: Figures 1-3

[0090] The oil phase reaction module 3, the water phase module 5 and the partition 4 are made of stainless steel 316L, the thickness of the oil phase reaction module 3 and the water phase module 5 is 2cm, the thickness of the partition 4 is 0.5cm, the three are overlapped and compacted, the interfaces are sealed by the perfluorinated rubber ring, and the mixed channel 8 and the oil phase reaction channel 9 are connected to form a continuous channel reactor after fastening.

[0091] The hydraulic diameters of the organic alcohol raw material inlet 1 and the organic acid raw material inlet 2 in the oil phase reaction module 3 are both set to 1000μm, the holdup of the mixing zone 10 is 15ml, the hydraulic diameter of the mixed channel 8 is 500μm; the holdups of the first reaction zone 11 and the second reaction zone 12 are 50ml and 100ml respectively, the hydraulic diameter of the oil phase reaction channel 9 is 500μm; the hydraulic diameter of the oil phase product outlet 6 is 5mm, the hydraulic diameter of the water phase product outlet 7 is 5mm, and the hydraulic diameter of the water phase product groove 14 is 1000μm.

[0092] ​The mixing channel 8 is embedded with a micro-grid mixing structure formed by a plurality of micro-grids 13, which is composed of a slit array precisely processed by laser, with a slit width of 50 μm, a slit pitch of 100 μm, and a projection angle of 45° between the slits of two adjacent micro-grids 13 in the material flow direction, and a pitch of 2 cm between the two adjacent micro-grids 13.

[0093] The separation membrane in the oil-water separation section 41 is a ceramic membrane, which uses a ceramic porous material as a substrate and is subjected to hydrophilic and oleophobic surface treatment, so that it can realize efficient in-situ oil-water separation, and the membrane hole diameter of the ceramic membrane is 500 nm.

[0094] (2) Synthesis of methyl mercaptoacetate:

[0095] Methanol raw material is input from the organic alcohol raw material inlet 1 as a medium to fill the entire device, and the reaction environment in the device is raised to the specified reaction temperature and pressure, and the methanol is circulated between the zones and the flow is controlled to the required flow by the mass flow meter. Mercaptoacetic acid containing 0.5% p-toluenesulfonic acid is input from the organic acid raw material inlet 2 into the oil phase reaction module 3, and after high-efficiency mixing by the micro-grid mixing structure, preliminary esterification reaction is carried out in the oil phase reaction channel 9 of the first reaction zone 11, and then enters the second reaction zone 12 for oil-water two-phase in-situ separation and promotes the esterification reaction in the oil phase reaction channel 9 to proceed in the positive direction, and the generated water phase product enters the water phase product groove 14 through the oil-water separation section 41, and finally the products are collected from the water phase product outlet 7 and the oil phase product outlet 6 respectively, and methyl mercaptoacetate is the main component of the oil phase product. Through liquid chromatography analysis, the yield of methyl mercaptoacetate is 95.4% and the selectivity of methyl mercaptoacetate is 98.4% during the reaction process.

[0096] When the conversion rate of the organic acid reaches 31.8%, the preliminary esterification reaction in the first reaction zone 11 is ended;

[0097] The first reaction conditions of the preliminary esterification in the first reaction zone 11 include a reaction temperature of 60°C and a residence time of 5 min;

[0098] The second reaction conditions of the deep esterification in the second reaction zone 12 include a reaction temperature of 80°C and a residence time of 10 min.

[0099] Example 4

[0100] In this embodiment, the liquid holdup of the first reaction zone 11 and the second reaction zone 12 is 30 ml and 100 ml respectively, and the product analysis results show that the yield of methyl mercaptoacetate is 90.4% and the selectivity of methyl mercaptoacetate is 98.9% during the reaction process.

[0101] Example 5

[0102] The steps in this example are basically the same as those in Example 1, except that the liquid holdup of the first reaction zone 11 and the second reaction zone 12 in this example are 50 ml and 80 ml respectively. The product analysis results show that the yield of methyl mercaptoacetate is 85.4% and the selectivity of methyl mercaptoacetate is 99.3% during the reaction process.

[0103] Example 6

[0104] The steps in this example are basically the same as those in Example 1, except that the slit width of the micro-grid mixed structure in this example is 1000 μm and the slit spacing is 150 μm. The product analysis results show that the yield of methyl mercaptoacetate is 92.3% and the selectivity of methyl mercaptoacetate is 98.1% during the reaction process.

[0105] Example 7

[0106] The steps in this example are basically the same as those in Example 1, except that the slit width of the micro-grid mixed structure in this example is 30 μm and the slit spacing is 70 μm. The product analysis results show that the yield of methyl mercaptoacetate is 96.1% and the selectivity of methyl mercaptoacetate is 98.8% during the reaction process.

[0107] Example 8

[0108] The steps in this example are basically the same as those in Example 1, except that the membrane hole diameter of the ceramic membrane in this example is 1000 nm. The product analysis results show that the yield of methyl mercaptoacetate is 94.6% and the selectivity of methyl mercaptoacetate is 97.7% during the reaction process.

[0109] Comparative Example 1

[0110] 200 g of mercaptoacetic acid and 100 g of methanol were added to a 2 L reaction kettle, 1.5 g of p-toluenesulfonic acid was added as a catalyst, and after reaction at 50 °C for 4 h, 1.0 g of p-toluenesulfonic acid was added to supplement the catalyst, and the reaction was continued for 3 h. The product was separated by oil-water separation and distilled to obtain methyl mercaptoacetate product. The liquid chromatography analysis shows that the yield of methyl mercaptoacetate is 85.2% and the selectivity of methyl mercaptoacetate is 92.3%.

[0111] The above results can show that the prior art has significant advantages in process efficiency and reaction time compared with the traditional batch synthesis process.

[0112] The preferred embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0113] It should also be noted that any technically feasible combination of the various technical features described in the above embodiments is possible, provided that there is no contradiction. In order to avoid unnecessary repetition, the present application will not describe the various possible combinations again.

[0114] Furthermore, any combination of the various embodiments of the present application is possible, provided that there is no contradiction with the idea of the present application, and should be considered as disclosed by the present application.

Claims

1. An esterification continuous reaction apparatus characterized by comprising: The device comprises: an oil phase reaction module (3) having a mixing zone (10), a first reaction zone (11) and a second reaction zone (12) connected in series along the material flow direction, the second reaction zone (12) being provided with an oil phase product outlet (6), the first reaction zone (11) and the second reaction zone (12) comprising an oil phase reaction channel (9) in communication; a water phase module (5) disposed below the oil phase reaction module (3), a part of the water phase module (5) being provided with a water phase product groove (14) and a water phase product outlet (7) disposed at one end of the water phase product groove (14) for leading out the water phase product; and a partition plate (4) disposed between the oil phase reaction module (3) and the water phase module (5), the partition plate (4) comprising an oil-water separation section (41) for separating the reaction material in the oil phase reaction channel (9) of the second reaction zone (12) into an oil phase and a water phase, the separated water phase flowing into the water phase product groove (14) and the oil phase flowing out from the oil phase product outlet (6); the mixing zone (10) is provided with a mixing channel (8) in communication with the oil phase reaction channel (9) connected to the oil phase product outlet (6), wherein the mixing channel (8) comprises an organic alcohol raw material inlet (1) and an organic acid raw material inlet (2) disposed in parallel, so that the organic alcohol raw material and the organic acid raw material are mixed in the mixing zone (10) and then enter the first reaction zone (11) and the second reaction zone (12) in sequence for esterification reaction; the oil phase reaction channel (9) in the second reaction zone (12) has a radial opening corresponding to the water phase product groove (14), and the oil-water separation section (41) is formed in the partition plate region between the oil phase reaction channel (9) and the opening of the water phase product groove (14); the mixing channel (8) is provided with a plurality of micro-grids (13) along the material flow direction.

2. The device according to claim 1, wherein, the hydraulic diameter of the organic acid raw material inlet (2) and the organic alcohol raw material inlet (1) is 500-2000 μm; and / or the thickness of the oil phase reaction module (3) and the water phase module (5) is 1-5 cm respectively; and / or the thickness of the partition plate (4) is 0.1-1 cm.

3. The device according to claim 2, wherein, the hydraulic diameter of the organic acid raw material inlet (2) and the organic alcohol raw material inlet (1) is 800-1000 μm.

4. The apparatus of claim 2, wherein, the thickness of the oil phase reaction module (3) and the water phase module (5) is the same.

5. The device according to claim 4, wherein, the slit width of the micro-grid (13) is 10-100 μm; and / or the slit spacing of the micro-grid (13) is 10-100 μm; and / or the spacing between two adjacent micro-grids (13) is 1-5 cm.

6. The device according to claim 5, wherein, the slit width of the micro-grid (13) is 40-60 μm; and / or the slit spacing of the micro-grid (13) is 40-60 μm; and / or The projection of the slits of two adjacent micro-grids (13) in the direction of the material flow has an included angle.

7. The apparatus of claim 6, wherein, The included angle is 10-60°.

8. The apparatus of claim 6, wherein, The included angle is 20-50°.

9. The apparatus of claim 1, wherein, The mixing channel (8) and / or the oil phase reaction channel (9) are arranged in a "Chinese character" shape in the oil phase reaction module (3).

10. The apparatus of claim 9, wherein, The hydraulic diameter of the mixing channel (8) is the same as the hydraulic diameter of the oil phase reaction channel (9).

11. The apparatus of claim 9, wherein, The hydraulic diameter of the mixing channel (8) and the hydraulic diameter of the oil phase reaction channel (9) are each 100-2000 μm.

12. The apparatus of claim 9, wherein, The hydraulic diameter of the mixing channel (8) and the hydraulic diameter of the oil phase reaction channel (9) are each 300-1500 μm.

13. The device of claim 1, wherein, The hydraulic diameter of the water phase product groove (14) is 100-5000 μm; and / or The liquid holdup of the mixing zone (10) is 5-50 ml; and / or The liquid holdup of the first reaction zone (11) is 10-100 ml; and / or The liquid holdup of the second reaction zone (12) is 50-200 ml; and / or The hydraulic diameter of the oil phase product outlet (6) is 1-10 mm, and the hydraulic diameter of the water phase product outlet (7) is 1-10 mm.

14. The device of claim 13, wherein, The hydraulic diameter of the water phase product groove (14) is 200-3000 μm; and / or The liquid holdup of the mixing zone (10) is 10-40 ml; and / or The liquid holdup of the first reaction zone (11) is 30-60 ml; and / or The liquid holdup of the second reaction zone (12) is 80-150 ml.

15. The apparatus of claim 1, wherein, The oil-water separation section (41) comprises a separation membrane selected from one of an organic membrane, an inorganic membrane or a composite membrane.

16. The apparatus of claim 15, wherein, The membrane pore diameter of the separation membrane is 100-1000 nm.

17. The device of any one of claims 1-16, wherein, The forming material of the oil phase reaction module (3) and / or the forming material of the water phase module (5) is selected from one or more of glass, metal and ceramic.

18. The apparatus of claim 17, wherein, The forming material of the oil phase reaction module (3) and / or the forming material of the water phase module (5) is selected from one or more of stainless steel 316L and Hastelloy C.

19. A method for the continuous synthesis of esters, characterized in that, The method is implemented by the esterification continuous reaction device of any one of claims 1-18, and the method comprises the following steps: 1) flowing the organic alcohol raw material into the entire device as a medium through the organic alcohol raw material inlet (1) and raising the reaction environment in the device to a specified reaction temperature and pressure; 2) mixing the organic acid raw material in the required proportion through the organic acid raw material inlet (2) with the organic alcohol raw material in the mixing channel (8), then entering the oil phase reaction channel (9) of the first reaction zone (11) to perform a preliminary esterification reaction under first reaction conditions, then entering the second reaction zone (12) to perform a deep esterification reaction under second reaction conditions, and obtaining a mixed reaction product; ​ 3) separating the aqueous phase product in the mixed reaction product of step 3) in-situ through the oil-water separation section (41) to promote the forward progress of the esterification reaction; wherein the oil phase product remains in the oil phase reaction channel (9) and the aqueous phase product enters the aqueous phase product groove (14), and the oil phase product and the aqueous phase product are collected at the oil phase product outlet (6) and the aqueous phase product outlet (7) respectively.

20. The method of claim 19, wherein, the organic alcohol is one or more of methanol, ethanol, isopropanol and n-propanol; and / or the organic acid is one or more of formic acid, acetic acid, mercaptoacetic acid and propionic acid.

21. The method of claim 19 or 20, wherein, the preliminary esterification reaction in the first reaction zone (11) is ended when the conversion rate of the organic acid reaches 10-40%; the first reaction conditions of the preliminary esterification in the first reaction zone (11) include a reaction temperature of 40-60°C and a residence time of 5-10 min; the second reaction conditions of the deep esterification in the second reaction zone (12) include a reaction temperature of 50-80°C and a residence time of 10-20 min.

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