Method for synthesizing furfuryl acetate through continuous reaction

Abstract

The invention belongs to the technical field of fine chemical synthesis, and particularly relates to a method for synthesizing furfuryl acetate through continuous reaction. The method is realized by utilizing a continuous reaction rectification system, and comprises the following steps of: reacting acetic acid and furfuryl alcohol serving as raw materials for a certain time in the presence of a catalyst, and then rectifying to obtain a furfuryl acetate product. According to the method for synthesizing the furfuryl acetate through the continuous reaction, the adopted device is a recyclable reactor, the whole device forms a closed loop in the aspect of acetic acid materials, and the whole device is energy-saving, high in automation degree, labor-saving, time-saving and labor-saving. The whole reaction is continuous, reactants are continuously input, products are continuously output, frequent charging, discharging and cleaning time in intermittent reaction are avoided, the production efficiency is remarkably improved, and the equipment utilization rate is high. And after the system is stable, the controllability of parameters such as temperature and concentration is high, the difference between batches is reduced, and the product quality is stable. The whole continuous reaction system is high in raw material utilization rate and few in side reaction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fine chemical synthesis, and particularly relates to a method for continuously synthesizing furfuryl acetate. BACKGROUND

[0002] Furfuryl acetate, also known as furfuryl acetate, is an important organic ester compound in the chemical industry. It can be used as fuel, resin, food flavor, perfume intermediate, solvent, etc. With its unique chemical properties and aroma characteristics, it has important applications in many industries. Furfuryl acetate has a sweet and sweet flavor similar to fruit or caramel, and is often used as a food additive to give candies, beverages, baked goods, etc. unique aroma. As a fragrance ingredient in personal care products such as perfumes, soaps, shampoos, etc., it provides a clean scent and enhances product appeal. Furfuryl acetate is often used in the paint, ink and resin industries as a solvent due to its high boiling point and good solubility, helping to dissolve cellulose derivatives or natural resins. Furfuryl acetate can be used as an important organic synthesis intermediate and pharmaceutical intermediate. Furfuryl acetate as a modifier of furfuryl alcohol resin improves the flexibility or corrosion resistance of the resin, and due to its origin from renewable resources, it has recently received extensive attention in the field of green chemistry, and can be used to develop biodegradable plastics or environmentally friendly adhesives. In addition, furfuryl acetate is explored as a cleaning agent or auxiliary film forming agent in semiconductor or photoresist technology. As a carrier solvent for pesticides or plant growth regulators, it helps to disperse active ingredients. With the rise of natural flavors and bio-based materials, the potential application of furfuryl acetate in the field of sustainable chemical industry is gradually being tapped.

[0003] The synthesis process of furfuryl acetate mainly includes traditional acid catalysis, acyl chloride method, solid superacid catalysis, etc. Different methods have differences in catalyst selection, reaction conditions and yield. The traditional acid catalytic esterification method has mature process and easy-to-get raw materials, but concentrated sulfuric acid corrodes equipment, has many side reactions, complex post-treatment and poor environmental protection. The acyl chloride method has high toxicity of raw materials, but has high requirements for reaction temperature, is suitable for laboratory scale, and has great difficulty in industrialization. The solid superacid catalyst method has a yield of 92%, and the catalyst can be reused for more than 6 times, but the solid superacid catalyst is relatively expensive, although it meets the trend of green chemistry, but it cannot be widely used in China at present.

[0004] Therefore, the inventors have researched and explored the synthesis process of furfuryl acetate, and proposed a process method for continuously synthesizing furfuryl acetate. By improving the synthesis process and adjusting the process parameters, the synthesis efficiency is improved, the environmental pollution is reduced, and the domestic blank in the continuous reaction synthesis of furfuryl acetate is filled, which has great market prospect and economic significance. SUMMARY

[0005] In view of the problems in the prior art, the application provides a method for continuously reacting and synthesizing furfuryl acetate, which utilizes a continuous reaction rectification system, adjusts process steps and process parameters, and improves the conversion rate and selectivity of raw materials in a circulating reaction mode, so that the synthesis efficiency is improved.

[0006] In order to achieve the above object, the application adopts the following technical scheme: The method for continuously reacting and synthesizing furfuryl acetate is realized by utilizing a continuous reaction rectification system, and comprises the following steps of: taking acetic acid and furfuryl alcohol as raw materials, reacting under the condition of a catalyst for a certain time, and then rectifying to obtain a furfuryl acetate product.

[0007] Specifically, the continuous reaction rectification system comprises a heating device, a three-necked flask, a lower-end rectification column, an intermediate conversion joint, an upper-end rectification column, a rectification head, a rectification receiving bottle (i.e., an acetic acid receiving bottle), an acetic acid feeding tank, an acetic acid feeding pump, and furfuryl alcohol feeding tank.

[0008] Specifically, the heating device is arranged at the bottom end of the three-necked flask, and is used for heating the three-necked flask, promoting the reaction, and rectifying the acetic acid and the furfuryl alcohol, and the heating device can be an oil bath pot.

[0009] Specifically, the acetic acid feeding tank is connected to one feeding pipe of the three-necked flask through an acetic acid feeding pipe, and the acetic acid feeding pump is arranged on the acetic acid feeding pipe.

[0010] Specifically, the rectification head is a U-shaped elbow structure with the opening downward, and comprises a bending part and left and right vertical parts. The bottom end of the lower-end rectification column is connected to one feeding pipe of the three-necked flask, the upper end of the lower-end rectification column is connected to the inlet end of the bottom part of the intermediate conversion joint, the outlet end of the top part of the intermediate conversion joint is connected to the inlet end of the bottom part of the upper-end rectification column, the outlet end of the top part of the upper-end rectification column is connected to the inlet end of the left vertical part of the rectification head, and the outlet end of the right vertical part of the rectification head is connected to the inlet end of the top part of the rectification receiving bottle.

[0011] Specifically, the right vertical part of the rectification head is provided with a first valve at the connection with the rectification receiving bottle.

[0012] Specifically, the outlet end of the bottom part of the rectification receiving bottle (i.e., the acetic acid receiving bottle) is connected to an acetic acid sampling pipe, the acetic acid sampling pipe is provided with two outlets, i.e., a qualified acetic acid outlet at the bottom and an acetic acid sampling port at the right side, the qualified acetic acid outlet of the acetic acid sampling pipe is provided with a second valve, and the acetic acid sampling port (i.e., an unqualified acetic acid outlet) of the acetic acid sampling pipe is provided with a third valve.

[0013] Specifically, the other pipe opening of the three-necked flask is a product sampling pipe port, and the product sampling pipe port is provided with a fifth valve and a product outlet pump.

[0014] Specifically, the intermediate conversion joint is sleeved with a thermometer sleeve, and a temperature sensor is arranged in the intermediate conversion joint, so that the temperature in the intermediate conversion joint can be measured.

[0015] Specifically, the intermediate conversion joint is sleeved with a thermometer sleeve, and a temperature sensor is arranged in the intermediate conversion joint, so that the temperature in the intermediate conversion joint can be measured.

[0016] Specifically, the qualified acetic acid outlet of the acetic acid sampling pipe is also connected with the acetic acid feeding tank through a pipeline.

[0017] Further, the continuous reaction distillation system is a two-stage distillation device, comprising a lower end distillation column and an upper end distillation column; the length of the upper end distillation column is 1-5 times the length of the lower end distillation column, preferably, the length of the upper end distillation column is 1-3 times the length of the lower end distillation column.

[0018] Further, the lower end distillation column is provided with packing (for example, glass spring packing) and catalyst, and the catalyst is a solid particle catalyst, which is mixed with the packing and then filled.

[0019] Further, the catalyst is a supported catalyst, specifically K2CO3-Al2O3 (trade name: LBW-547), CsCO3-Al2O3 (trade name: RFH-534), Na2CO3-Al2O3, quaternary ammonium salt type anion resin (model: A-8XMP) and Fe3O 4@ SiO2-Mg (trade name: RB969TT) and the like.

[0020] Further, the catalyst loading amount in the lower end distillation column is 10g-100g, preferably 50g.

[0021] Further, the method for continuously synthesizing furfuryl acetate according to the present application comprises the following steps: (1) First, according to the foregoing, the continuous reaction distillation system is built; Before the reaction, the fourth valve, the fifth valve, the second valve, the third valve are closed, and the first valve is opened. During the reaction, acetic acid is first pumped into the three-necked flask through the acetic acid feed tank, the acetic acid feed pipe and the acetic acid feed pump, and then the heating device oil bath is used to heat to 160-180℃, so that the acetic acid is heated to boil to form steam. The acetic acid steam passes through the lower end rectification column, the intermediate conversion joint, the upper end rectification column and the rectification head in turn. When acetic acid distillate appears in the rectification head, the reflux ratio is adjusted. At this time, the acetic acid entering the rectification receiving bottle is acetic acid with a water content (mass fraction) of less than 1%. The second valve is opened, and the three-necked flask, the lower end rectification column, the intermediate conversion joint, the upper end rectification column, the rectification head, the rectification receiving bottle and the acetic acid sampling pipe are connected with the acetic acid feed tank to form an acetic acid circulation system, so that the acetic acid raw material flow can be returned to the acetic acid feed tank for reuse. (2) After the system is stable, the furfuryl alcohol is pumped from the furfuryl alcohol feed tank into the intermediate conversion joint through the intermediate feed port by using the furfuryl alcohol feed pump. After the system is stable, the acetic acid steam in the ascending process of heating rectification reacts with the furfuryl alcohol entering the intermediate conversion joint under the action of the catalyst to generate furfuryl acetate. The reaction liquid and the refluxing acetic acid flow into the three-necked flask, and the furfuryl acetate is collected in the three-necked flask. After 0.5-2h of reaction, the fifth valve is opened, and the reaction liquid is pumped out by the product discharge pump to obtain the reaction product (furfuryl acetate).

[0022] Further, in the method, the discharge rate of the final reaction liquid is in a certain proportion to the feeding rate of acetic acid, and the feeding rate of furfuryl alcohol is in a certain proportion to the feeding rate of acetic acid.

[0023] Further, in step (1), the pump speed when the acetic acid is first added is 8-12ml / min.

[0024] Further, in step (1), the amount of acetic acid pumped into the three-necked flask is 1 / 10-1 / 2 of the volume of the three-necked flask; preferably, the amount of acetic acid pumped is 1 / 5-1 / 2 of the volume of the three-necked flask.

[0025] Further, in step (1), the reflux ratio during the rectification is 3:1-10:1; preferably, the rectification reflux ratio is 5:1-10:1.

[0026] Further, in step (1), when acetic acid distillate appears in the rectification head, the pump speed of the acetic acid feed pump is adjusted to 3-8ml / min.

[0027] Further, in step (1), when the water content (mass fraction) of acetic acid entering the rectification receiving bottle exceeds 1%, the 3A molecular sieve is dried at 350 DEG C for 2-4 h, then cooled to room temperature, and sealed for storage. A dehydration column 40 cm high is built, and the acetic acid with water content exceeding 1% is flowed through the dehydration column at a flow rate of 5 ml / min, and the dried molecular sieve is used for dehydration treatment. After the water content is qualified, the acetic acid is reused.

[0028] Further, in step (2), the furfuryl alcohol is fed from the furfuryl alcohol feed tank into the intermediate conversion joint through the intermediate feed port by using a furfuryl alcohol feed pump, and the pump speed is 1-2 ml / min.

[0029] Further, in step (2), the reaction temperature is 100-110 DEG C; preferably, the temperature is 105-110 DEG C.

[0030] Further preferably, in step (2), the reaction time is 1-1.5 h.

[0031] Further, in step (2), the intermediate conversion joint is provided with a heating belt, which can heat or control the temperature of the intermediate conversion joint. After the reaction in the intermediate conversion joint is stable, the fluctuation of the reaction temperature is only 2 DEG C, which is within the error range and can meet the experimental conditions.

[0032] Further, in step (2), the pump-out rate of the reaction liquid is 2-8 ml / min.

[0033] Further, in step (2), the ratio of the discharge rate of the reaction liquid to the feeding rate of acetic acid is 1:1.2-1:1.5, and the ratio of the feeding rate of acetic acid to the feeding rate of furfuryl alcohol is 1:1-20:1; preferably, the ratio of the feeding rate of acetic acid to the feeding rate of furfuryl alcohol is 5:1-10:1.

[0034] The continuous reaction rectification system of the application does not need to add toluene or benzene as an azeotropic solvent, and acetic acid as a raw material can also serve as an azeotropic solvent, so that the generation of impurities can be avoided.

[0035] Compared with the prior art, the application has the following advantages: 1. The continuous reaction and synthesis method of acetic acid furfuryl ester of the application uses a recyclable reactor, and the whole device forms a closed loop in terms of acetic acid material, so that the device is energy-saving, highly automated, labor-saving and time-saving. The whole reaction is a continuous reaction, the reactants are continuously input, and the products are continuously output, so that the frequent charging, discharging and cleaning time in the batch reaction is avoided, the production efficiency is significantly improved, the equipment utilization rate is high, the temperature, concentration and other parameters are controllable after the system is stabilized, the batch differences are reduced, the product quality is stable, the raw material utilization rate is high, the side reactions are few, the opportunities of personnel contact with dangerous in the operation process are reduced, and the accident risk is reduced.

[0036] 2、The continuous reaction rectification system provided by the application has no azeotrope agent, and acetic acid, by virtue of its low boiling point, participates in the reaction and promotes the forward reaction by carrying water through its steam, thereby improving the conversion rate and selectivity of the product, saving cost and reducing the difficulty of process separation without introducing new substances.

[0037] 3、The synthesis method provided by the application has higher selectivity and conversion rate than the selectivity and conversion rate of the current acetic acid furfuryl ester synthesis process. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The figure is a structural schematic diagram of the continuous reaction rectification system described in the application. DETAILED DESCRIPTION

[0039] In order to make the technical objects, technical solutions and beneficial effects of the application clearer, the technical solutions of the application will be further described below in combination with specific examples, but the examples are intended to explain the application and cannot be understood as limiting the application, and the specific technologies or conditions not mentioned in the examples are performed according to the technologies or conditions described in the literature in the field or according to the product instructions.

[0040] In the following examples, room temperature or normal temperature refers to 25±5℃.

[0041] In the following examples, the product acetic acid furfuryl ester is determined by gas chromatography, specifically as follows: 1.1 Gas chromatograph (GC8860) provided with a hydrogen flame ionization detector and a chromatographic data workstation, the sensitivity and stability of which should meet GB / T 97222-2006; 1.2 Chromatographic column: HP-5, inner diameter 0.32mm, column length 30m, film thickness 0.25μm; 1.3 Microsyringe: 10μL; 1.4 Nitrogen: purity greater than 99.999%; 1.5 Hydrogen: purity greater than 99.999%; 1.6 Purified air.

[0042] 2. Chromatographic separation conditions Injection volume: 0.2 μL; Carrier gas flow rate: 1.0 mL / min; Injector temperature: 280 °C; Detector temperature: 300 °C; Split ratio: 40:1; Hydrogen flow rate: 40 mL / min; Air flow rate: 400 mL / min. HP-5 capillary column; Oven temperature: 50 °C for 5 min, ramped up to 240 °C at 10 °C / min, held for 1 min, ramped up to 280 °C at 20 °C / min, held for 30 min. Elution order: Acetic acid: 3.5 min; Furfuryl alcohol: 8.0 min; Furfuryl acetate: 11.9 min.

[0043] 3. Sample determination After the chromatograph is started with carrier gas, the chromatographic conditions are set and the temperature is increased. When all components of the chromatograph (injector, detector, column temperature) reach the set values, hydrogen and air are introduced, the detector is ignited, and after the instrument baseline stabilizes, a clean and dry microsyringe is used to measure the sample and inject it into the injection port. After all components have eluted, the analysis ends. The chromatographic workstation provides the area of ​​each peak and uses the area normalization method to give the percentage content of each component.

[0044] Example 1 A method for the continuous reaction synthesis of furfuryl acetate, specifically implemented using a continuous reactive distillation system, such as... Figure 1 As shown, the continuous reactive distillation system includes a heating device 1, a three-necked flask 2, a lower distillation column 3 (filled with packing material (glass spring packing) and K2CO3-Al2O3 catalyst (catalyst loading amount is 50g)), an intermediate conversion connector 4, an upper distillation column 5, a distillation head 6, a distillation receiving flask 7 (i.e., acetic acid receiving flask), an acetic acid feed tank 9, an acetic acid feed pump (not shown in the figure), and a furfuryl alcohol feed tank 8; Heating device 1 (specifically a DF-101S type oil bath) is set at the bottom of the three-necked flask 2 to heat the three-necked flask 2, promote the reaction, and distill acetic acid and furfuryl alcohol. Heating device 1 adopts equipment commonly used in the prior art, and its structure and principle are not the inventive point of this invention, so they will not be described in detail. Acetic acid feed tank 9 is connected to one of the feed pipes of three-necked flask 2 via acetic acid feed pipe (specifically...) Figure 1 The rightmost feed pipe 21 is connected to the acetic acid feed pipe; the acetic acid feed pump is installed on the acetic acid feed pipe; The distillation head 6 is a U-shaped bend with a downward U-shaped opening, including a middle bend, a left vertical section, and a right vertical section; The bottom end of the lower distillation column 3 is connected to one of the feed pipes of the three-necked flask 2 (specifically...) Figure 1The middle feed pipe is connected to the upper end of the lower distillation column 3, the upper end of the middle conversion joint 4 is connected to the bottom inlet end of the middle conversion joint 4, the top outlet end of the middle conversion joint 4 is connected to the bottom inlet end of the upper distillation column 5, the top outlet end of the upper distillation column 5 is connected to the left vertical part inlet end of the distillation head 6, and the right vertical part outlet end of the distillation head 6 is connected to the top inlet end of the distillation receiving bottle 7. A first valve is provided at the connection between the right vertical part of the distillation head 6 and the distillation receiving bottle 7; An acetic acid sampling tube is connected to the outlet end of the bottom of the distillation receiving flask 7 (i.e., the acetic acid receiving flask). The acetic acid sampling tube has two outlets: the qualified acetic acid outlet 71 at the bottom and the acetic acid sampling outlet 72 on the right side. A second valve is provided at the qualified acetic acid outlet of the acetic acid sampling tube, and a third valve is provided at the acetic acid sampling outlet 72 (i.e., the unqualified acetic acid outlet). The other opening of the pipe in the three-necked flask 2 (specifically...) Figure 1 The leftmost pipe opening (23) is the product sampling port, where a fifth valve and a product discharge pump (not shown in the figure) are located. The intermediate adapter 4 is fitted with a thermometer sleeve, and a temperature sensor (not shown in the figure) is installed inside the intermediate adapter 4, which can measure the temperature inside the intermediate adapter 4; The intermediate conversion joint 4 has an intermediate feed port 41. The furfuryl alcohol feed tank 8 is connected to the intermediate feed port 41 through a pipeline. A fourth valve is provided on the pipeline connecting the furfuryl alcohol feed tank 8 and the intermediate feed port 41. By adjusting the fourth valve, the feed of furfuryl alcohol feed tank 8 can be controlled. A furfuryl alcohol feed pump (not shown in the figure) is also provided on the pipeline connecting the furfuryl alcohol feed tank 8 and the intermediate feed port 41. In this embodiment, the three-necked flask 2 has a capacity of 100 mL.

[0045] The length of the upper distillation column 5 is 1 to 3 times the length of the lower distillation column 3.

[0046] The equipment in the continuous reactive distillation system described in this invention all use conventional equipment in the prior art, and are not the inventive point of this invention, so they will not be described in detail here. The method comprises the following specific steps: (1) First, based on the foregoing content, construct the continuous reactive distillation system; Before the reaction, close the fourth, fifth, second, and third valves, and open the first valve. During the reaction, add 30g of acetic acid to the 100mL three-necked flask 2 through the acetic acid feed tank 9, acetic acid feed pipe, and acetic acid feed pump (the pump speed at the beginning of adding acetic acid is 10ml / min). Then, use the heating device 1 to heat the oil bath to 165℃ to heat the acetic acid to boiling and form steam. The acetic acid steam rises and passes through the lower distillation column 3, the intermediate conversion connector 4, the upper distillation column 5, and the distillation head 6 in sequence. When acetic acid fraction appears in the distillation head 6, adjust the reflux ratio to 5:1 and set the acetic acid feed pump speed to 6 ml / min. At this time, the acetic acid entering the distillation receiving flask 7 is acetic acid with a water content (mass fraction) of less than 1%. Connect the qualified acetic acid outlet of the acetic acid sampling tube to the acetic acid feed tank 9 through a pipeline. Open the second valve and connect the three-necked flask 2, the lower distillation column 3, the intermediate conversion connector 4, the upper distillation column 5, the distillation head 6, the distillation receiving flask 7, the acetic acid sampling tube, and the acetic acid feed tank 9 to form an acetic acid circulation system.

[0047] (2) After the system stabilizes, furfuryl alcohol is fed from furfuryl alcohol feed tank 8 through intermediate feed port 41 into intermediate conversion joint 4 using furfuryl alcohol feed pump. The pump speed is 1 ml / min. After the system stabilizes, acetic acid vapor reacts with furfuryl alcohol entering intermediate conversion joint 4 under the action of catalyst during the rising process of heating distillation to generate furfuryl acetate. The reaction temperature is 105℃ (the intermediate conversion joint 4 is equipped with a heating belt, which can keep the intermediate conversion joint 4 warm or control the temperature. After the reaction in the intermediate conversion joint 4 stabilizes, the reaction temperature fluctuates by only 2℃, which is within the error range and can meet the experimental conditions; specifically, the heating belt adopts the conventional setting in the prior art. Its structure and the setting method with intermediate conversion joint 4 are conventional means and are not the inventive point of this invention, so they will not be described in detail). Continue to maintain the evaporation rate of acetic acid in three-necked flask 2. The acetic acid vapor carries away the water from the reaction process, allowing the reaction to proceed further towards the direction of furfuryl acetate. The reaction solution and refluxed acetic acid were placed in a three-necked flask 2. Furfural acetate was collected in the three-necked flask 2. After reacting for 1 hour, the fifth valve was opened, and the reaction solution was pumped out through the product discharge pump to obtain the reaction product (furfural acetate). The pumping rate of the reaction solution was 5 ml / min.

[0048] Throughout the reaction, the conversion rate was 86% and the selectivity was 92% (detected by gas chromatography).

[0049] The entire reaction process is a continuous reaction with a catalyst lifetime of 3000 h. The feed rate of furfuryl alcohol is 60 ml per hour, and the feed rate of acetic acid is 360 ml. The acetic acid and furfuryl alcohol remaining in the collected reaction solution can be separated by distillation. Acetic acid and unreacted furfuryl alcohol are recycled back to the system to continue the reaction.

[0050] The catalyst K2CO3-Al2O3 mentioned in Example 1 is specifically the commercial brand name: LBW-547.

[0051] The instruments and equipment used in the reaction process include heating device 1, three-necked flask 2, lower distillation column 3, intermediate conversion connector 4, temperature sensor, upper distillation column 5, distillation head 6, distillation receiving flask 7, acetic acid feed tank 9, acetic acid feed pump, furfuryl alcohol feed tank 8, etc., which are all common equipment in the prior art. The specific usage methods adopt the conventional usage methods in the prior art and are not the inventive point of this invention, so they will not be described in detail.

[0052] Example 2 A method for the continuous reaction synthesis of furfuryl acetate, Example 2 differs from Example 1 in that: The lower distillation column 3 is filled with packing material and CsCO3-Al2O3 catalyst (catalyst loading amount is 50g).

[0053] Throughout the reaction, the conversion rate was 88% and the selectivity was 95% (detected by gas chromatography).

[0054] The catalyst CsCO3-Al2O3 described in Example 2 is specifically the commercial brand name: RFH-534.

[0055] Example 3 A method for the continuous reaction synthesis of furfuryl acetate, Example 3 differs from Example 1 in that: The lower distillation column 3 is filled with packing material and Na2CO3-Al2O3 catalyst (catalyst loading amount is 50g).

[0056] Throughout the reaction, the conversion rate was 86% and the selectivity was 93% (detected by gas chromatography).

[0057] The Na2CO3-Al2O3 catalyst described in Example 3.

[0058] Example 4 A method for the continuous reaction synthesis of furfuryl acetate, Example 4 differs from Example 1 in that: The lower distillation column 3 is packed with packing material and Fe3O4. 4@ SiO2-Mg catalyst (catalyst loading amount is 50g).

[0059] Throughout the reaction, the conversion rate was 90% and the selectivity was 95% (detected by gas chromatography).

[0060] The catalyst Fe3O described in Example 4 4@ The specific brand name of SiO2-Mg is RB969TT.

[0061] Example 5 A method for the continuous reaction synthesis of furfuryl acetate, Example 5 differs from Example 1 in that: The lower distillation column 3 is filled with packing material and quaternary ammonium salt anion exchange resin catalyst (catalyst loading amount is 50g).

[0062] Throughout the reaction, the conversion rate was 89% and the selectivity was 97% (detected by gas chromatography).

[0063] The catalyst described in Example 5 is a quaternary ammonium salt anion exchange resin catalyst, specifically model A-8XMP.

[0064] The specific data for each embodiment of the present invention are shown in Table 1 below.

[0065] Table 1 It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for the continuous reaction synthesis of furfuryl acetate, characterized in that, The process is achieved using a continuous reactive distillation system, which includes a heating device, a three-necked flask, a lower distillation column, an intermediate conversion connector, an upper distillation column, a distillation head, a distillation receiving flask, an acetic acid feed tank, an acetic acid feed pump, and a furfuryl alcohol feed tank. The heating device is located at the bottom of the three-necked flask and is used to heat the three-necked flask. The acetic acid feed tank is connected to one of the feed pipes of a three-necked flask via an acetic acid feed pipe; the acetic acid feed pump is installed on the acetic acid feed pipe; The distillation head is a U-shaped bend structure with a U-shaped opening facing downwards, including a bend, a left vertical section, and a right vertical section; The bottom end of the lower distillation column is connected to a feed pipe of a three-necked flask, the top end of the lower distillation column is connected to the inlet end of the bottom of the intermediate conversion connector, the outlet end of the top of the intermediate conversion connector is connected to the inlet end of the bottom of the upper distillation column, the outlet end of the top of the upper distillation column is connected to the inlet end of the left vertical part of the distillation head, and the outlet end of the right vertical part of the distillation head is connected to the inlet end of the top of the distillation receiving bottle. An acetic acid sampling tube is connected to the outlet end at the bottom of the distillation receiving flask. The acetic acid sampling tube has two outlets: a qualified acetic acid outlet at the bottom and an acetic acid sampling outlet on the right side. A second valve is provided at the qualified acetic acid outlet of the acetic acid sampling tube, and a third valve is provided at the acetic acid sampling outlet of the acetic acid sampling tube. The intermediate conversion joint has an intermediate feed port. The furfuryl alcohol feed tank is connected to the intermediate feed port through a pipeline. A fourth valve is installed on the pipeline connecting the furfuryl alcohol feed tank and the intermediate feed port. By adjusting the fourth valve, the feed of furfuryl alcohol into the feed tank can be controlled. A furfuryl alcohol feed pump is also installed on the pipeline connecting the furfuryl alcohol feed tank and the intermediate feed port.

2. The method according to claim 1, characterized in that, A first valve is provided at the connection between the right vertical part of the distillation head and the distillation receiving bottle; The other pipe opening of the three-necked flask is the product sampling port, which is equipped with a fifth valve and a product discharge pump. The intermediate conversion connector is fitted with a thermometer sleeve, and a temperature sensor is installed inside the intermediate conversion connector.

3. The method according to claim 1, characterized in that, The qualified acetic acid outlet of the acetic acid sampling tube is also connected to the acetic acid feed tank via a pipeline.

4. The method according to claim 1, characterized in that, The length of the upper distillation column is 1 to 5 times the length of the lower distillation column.

5. The method according to claim 1, characterized in that, The lower distillation column is filled with packing material and catalyst. The catalyst is a solid particulate catalyst, which is mixed evenly with the packing material before being loaded. The catalyst is a supported catalyst, specifically K2CO3-Al2O3, CsCO3-Al2O3, Na2CO3-Al2O3, quaternary ammonium salt anion exchange resin, and Fe3O4. 4@ One or more of SiO2-Mg.

6. The method according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) First, the continuous reactive distillation system is constructed; Before the reaction, close the fourth, fifth, second, and third valves, and open the first valve. During the reaction, acetic acid is first pumped into the three-necked flask through the acetic acid feed tank, acetic acid feed pipe, and acetic acid feed pump. Then, the acetic acid is heated to 160-180°C using an oil bath heating device to boil and form steam. The acetic acid steam rises and passes sequentially through the lower distillation column, the intermediate conversion connector, the upper distillation column, and the distillation head. When acetic acid fraction appears in the distillation head, adjust the reflux ratio. At this point, the acetic acid entering the distillation receiving flask has a water content of less than 1%. Open the second valve to connect the three-necked flask, the lower distillation column, the intermediate conversion connector, the upper distillation column, the distillation head, the distillation receiving flask, the acetic acid sampling tube, and the acetic acid feed tank to form an acetic acid circulation system. The acetic acid raw material can be returned to the acetic acid feed tank for reuse. (2) After the system stabilizes, use the furfuryl alcohol feed pump to feed furfuryl alcohol from the furfuryl alcohol feed tank through the intermediate feed port to the intermediate conversion joint; after the system stabilizes, the acetic acid vapor reacts with the furfuryl alcohol that enters at the intermediate conversion joint under the action of the catalyst during the rising process of heating distillation to generate furfuryl acetate. The reaction liquid and the refluxed acetic acid are placed in a three-necked flask. The furfuryl acetate is collected in the three-necked flask. After the reaction is carried out for 0.5 to 2 hours, the fifth valve is opened and the reaction liquid is pumped out through the product discharge pump to obtain the reaction product.

7. The method according to claim 6, characterized in that, In step (1), acetic acid with a volume of 1 / 10 to 1 / 2 of the three-necked flask is pumped into the three-necked flask.

8. The method according to claim 6, characterized in that, In step (1), the reflux ratio during distillation is 3:1 to 10:

1.

9. The method according to claim 6, characterized in that, In step (2), the reaction temperature is 100~110℃.

10. The method according to claim 6, characterized in that, In step (2), the ratio of the discharge rate of the reaction solution to the feed rate of acetic acid is 1:1.2 to 1:1.5, and the ratio of the feed rate of acetic acid to the feed rate of furfuryl alcohol is 1:1 to 20:1.

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