Continuous production device and method of high-purity isosorbide

Abstract

The invention belongs to the field of fine chemical engineering, and particularly relates to a continuous production device and method of high-purity isosorbide. The device comprises a reaction unit, a separation unit and a purification unit which are sequentially connected, the reaction unit comprises a preheater and a reactor, the separation unit comprises a settling tank, a filter, a dehydrating tower and a distillation tower, and the purification unit comprises a decolorizing tower, a rectifying tower and a crystallizing tower. A sorbitol raw material enters a preheater to be preheated, the preheated material enters a reactor to be subjected to a dehydration reaction, the reacted material flows out of a discharging port in the upper portion of the reactor to enter a shell pass of a dehydration tower to be subjected to heat exchange and cooling, the cooled material enters a settling tank to settle solid waste, supernate enters a filter to be filtered, and a liquid phase flows into the dehydration tower to be subjected to water removal and concentration; and distilling out crude isosorbide in a distillation tower, and purifying the isosorbide crude product through a decolorizing tower, a rectifying tower and a crystallizing tower to obtain the high-purity isosorbide. The method has the outstanding characteristics of continuous production, separation and purification, and continuous production of high-purity isosorbide can be realized.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and specifically relates to a continuous production device and method for high-purity isosorbide. Background Art

[0002] Isosorbide is a high value-added bio-based material that can be used to synthesize a series of high-performance polymers, additives, etc. for use in medicine, cosmetics, electronics and other fields. In industry, concentrated sulfuric acid is generally used to catalyze the dehydration of molten sorbitol to produce isosorbide. However, the concentrated sulfuric acid system has high operating risks, serious carbonization of reactants, violent side reactions, difficulty in continuous production and the inability to reuse catalysts. The resulting product has low purity, small production scale, and cannot form continuous production. Solid acid is a new type of green and efficient catalyst. Titanium sulfate, phosphate, aluminum silicate molecular sieve, sulfonic acid resin, heteropoly acid, etc. can efficiently catalyze the dehydration of sorbitol, and the yield of isosorbide even exceeds 90%. Patent CN201180071366.2 discloses a two-step dehydration reaction process for producing isosorbide using sulfuric acid and mixed acid to catalyze the dehydration of sorbitol. After the reaction, it is necessary to undergo alkali neutralization, decolorization, concentration, distillation and other processes to obtain isosorbide with a purity of more than 99%. At present, the preparation process of isosorbide is mainly based on intermittent process, and the reaction and purification process are difficult to operate continuously, resulting in low isosorbide yield and purity, poor repeatability and economy.

[0003] In view of the above problems, it is therefore urgent to develop a continuous production process for high-purity isosorbide. Summary of the invention

[0004] In view of the problems and deficiencies in the prior art, the purpose of the present invention is to provide a continuous production device and method for high-purity isosorbide. The present invention is divided into three parts: a reaction unit, a separation unit and a purification unit. The reaction unit and the separation unit are thermally coupled to improve the thermal efficiency of the process. The reaction unit consists of three parts: feeding, preheating and a continuous reactor, which mainly completes the continuous feeding and reaction process; the separation unit mainly includes four parts such as a sedimentation solid-liquid separation tank, a filter, a dehydration tower and a distillation tower. It is a crude product production process, and solid particles such as catalyst powder are removed by sedimentation and filtration, and then crude isosorbide is obtained by dehydration and distillation; the purification unit mainly includes decolorization, distillation and recrystallization processes to obtain >99% high-purity pharmaceutical grade or polymerization grade isosorbide. The material out of the reactor enters the sedimentation tank after heat exchange in the dehydration tower, which fully improves the thermal efficiency. The heavy components at the bottom of the distillation tower or the rectification tower are returned to the preheater for reuse after washing and decolorization, and continue to participate in the reaction, thereby improving the total yield of the product.

[0005] Based on the above purpose, the present invention adopts the following technical solution: The invention provides a continuous production device for high-purity isosorbide, comprising a reaction unit, a separation unit and a purification unit which are connected in sequence; the reaction unit comprises a preheater and a reactor; the separation unit comprises a sedimentation tank, a filter, a dehydration tower and a distillation tower; the purification unit comprises a decolorization tower, a distillation tower and a crystallization tower.

[0006] Furthermore, the lower discharge port of the preheater is connected to the lower feed port of the reactor; the upper discharge port of the reactor is connected to the upper shell side feed port of the dehydration tower, the lower shell side discharge port of the dehydration tower is connected to the upper feed port of the settling tank, the lower discharge port of the settling tank is connected to the upper feed port of the filter, the lower discharge port of the filter is connected to the lower feed port of the dehydration tower, and the upper discharge port of the dehydration tower is connected to the lower feed port of the distillation tower; the upper discharge port of the distillation tower is connected to the upper feed port of the bleaching tower, the lower discharge port of the bleaching tower is connected to the middle feed port of the distillation tower, and the upper discharge port of the distillation tower is connected to the upper feed port of the crystallization tower; the lower discharge port of the distillation tower and the lower discharge port of the distillation tower are both connected to the upper feed port of the preheater.

[0007] Furthermore, a catalyst feed port is provided at the upper portion of the reactor, a waste catalyst discharge port is provided at the lower portion of the reactor, and a solid waste discharge port is provided at the lower portion of the filter.

[0008] The present invention also provides a method for continuously producing isosorbide using the above device, comprising the following steps: (1) Reaction: The sorbitol raw material enters the preheater for preheating. The preheated material enters the reactor for dehydration reaction at 120-200 °C under the action of a catalyst. The reacted material flows out from the discharge port at the top of the reactor. (2) Separation: The reacted material enters the shell side of the dehydration tower for heat exchange and cooling. After cooling, it enters the sedimentation tank to settle the solid waste. The supernatant enters the filter for filtration. The liquid phase flows into the dehydration tower for dehydration and concentration at a temperature of 60 to 130 °C and a vacuum degree of -0.1 to -0.3 MPa. It then enters the distillation tower for distillation at a temperature of 150 to 250 °C and a vacuum degree of -0.1 to -0.3 MPa to obtain crude isosorbide. (3) Purification: The crude isosorbide is purified by a decolorization tower, a distillation tower and a crystallization tower to obtain high-purity isosorbide.

[0009] Furthermore, the sorbitol raw material is pure sorbitol or sorbitol solution melted at high temperature; the sorbitol solution is an industrial-grade 30% to 70% sorbitol solution.

[0010] Furthermore, when the sorbitol raw material is pure sorbitol melted at high temperature, the preheating temperature is 100-130°C; when the sorbitol raw material is sorbitol solution, the preheating temperature is 30-80°C.

[0011] Preferably, the preheating temperature is 80-120°C.

[0012] Preferably, the operating temperature of the distillation tower is 180 to 210° C., and the vacuum degree is -0.1 to -0.08 MPa.

[0013] Furthermore, in step (3), the temperature of the distillation tower kettle is 150-250° C.; and the mass ratio of crude isosorbide to crystallization solvent in the crystallization tower is 1:2.5-7.

[0014] Furthermore, before the sorbitol raw material in step (1) enters the reactor, the reactor needs to be purged with N2 to remove water, vacuum to remove water, or directly not to remove water.

[0015] Furthermore, the filter adopts pressure filtration, pressure reduction filtration or centrifugal filtration.

[0016] Preferably, the filtering method is centrifugal filtration.

[0017] Furthermore, the decolorizing agent in the decolorizing tower is any one of activated carbon, kaolin or resin.

[0018] Preferably, the decolorizing agent is activated carbon.

[0019] Furthermore, the crystallization solvent is any one of ethyl acetate, methanol, ethanol and ethylene glycol.

[0020] Furthermore, the catalyst is any one of polymeric ionic liquid, niobium oxide, niobium phosphate, and molecular sieve.

[0021] Furthermore, the solid waste settled in the sedimentation tank is a pulverized catalyst.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a method for continuous production of high-purity isosorbide, which uses sorbitol or a sorbitol solution as a reaction material, firstly obtains isosorbide through preheating and reaction, then separates the solid waste in the reaction system through sedimentation and filtration, and then obtains crude isosorbide through dehydration and distillation processes, and finally obtains a high-purity isosorbide product through decolorization, rectification and recrystallization processes. Compared with the traditional intermittent production process, the outstanding feature of this process is continuous production and separation and purification, which can realize the continuous production of high-purity isosorbide. Among them, (1) The process of preparing isosorbide from sorbitol is a dehydration reaction. Usually, the reaction materials need to be pre-dehydrated before entering the reactor. However, in the present invention, the materials entering the reactor do not need to be pre-dehydrated. Direct liquid feeding greatly simplifies the process flow and reduces the process cost. On the other hand, it ensures the fluidity of the materials, making the feeding process system simpler and facilitating the realization of continuous pump-type feeding. (2) The reactor can be purged with N2 to remove water, vacuum to remove water, or directly react without removing water. Direct reaction is preferred, as the process is simpler and the operation and maintenance costs are lower. (3) The process includes sedimentation and filtration to remove impurities, which prevents catalyst powder and coking polymers from entering the distillation and purification process, which is beneficial to improving the yield and purity of isosorbide; (4) The outstanding feature of the present invention is that the reaction stage does not remove water, the dehydration stage is moved back, the process integration is higher, and at the same time, the thermal coupling of the reaction and dehydration processes is achieved, which greatly improves the thermal efficiency of the process; (5) The total yield of the product is increased by recycling the heavy components in the distillation tower and the rectification tower; (6) The feed of the present invention does not require solvent addition, the process is greener, and the waste liquid is only the aqueous phase without solvent.

[0023] The raw material of the present invention has wider applicability, and is applicable to both pure sorbitol and sorbitol aqueous solution feed. The reaction conditions are mild, and continuous operation of the reaction, separation and purification processes can be realized to obtain isosorbide with a purity of >99%, which greatly promotes the industrialization of continuous polymerization-grade or pharmaceutical-grade isosorbide. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of a continuous production device for high-purity isosorbide of the present invention; Figure 2 The present invention is a preparation flow chart for the continuous production of high-purity isosorbide.

[0025] In the figure: 1-preheater; 2-reactor; 3-sedimentation tank; 4-filter; 5-dehydration tower; 6-distillation tower; 7-decolorization tower; 8-rectification tower; 9-crystallization tower. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through embodiments in combination with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Example 1 This embodiment provides a continuous production device for high-purity isosorbide, the schematic diagram of which is shown in FIG. Figure 1 As shown, it includes a reaction unit, a separation unit and a purification unit connected in sequence; the reaction unit includes a preheater 1 and a reactor 2; the separation unit includes a sedimentation tank 3, a filter 4, a dehydration tower 5 and a distillation tower 6; the purification unit includes a decolorization tower 7, a distillation tower 8 and a crystallization tower 9.

[0028] The lower discharge port of the preheater 1 is connected to the lower feed port of the reactor 2; the upper discharge port of the reactor 2 is connected to the upper shell side feed port of the dehydration tower 5, the lower shell side discharge port of the dehydration tower 5 is connected to the upper feed port of the settling tank 3, the lower discharge port of the settling tank 3 is connected to the upper feed port of the filter 4, the lower discharge port of the filter 4 is connected to the lower feed port of the dehydration tower 5, the upper discharge port of the dehydration tower 5 is connected to the lower feed port of the distillation tower 6; the upper discharge port of the distillation tower 6 is connected to the upper feed port of the decolorization tower 7, the lower discharge port of the decolorization tower 7 is connected to the middle feed port of the distillation tower 8, and the upper discharge port of the distillation tower 8 is connected to the upper feed port of the crystallization tower 9; the lower discharge port of the distillation tower 6 and the lower discharge port of the distillation tower 8 are both connected to the upper feed port of the preheater. The reactor 2 is also provided with a catalyst feed port at the top, and a waste catalyst discharge port at the bottom; the filter 4 is provided with a solid waste discharge port at the bottom.

[0029] Example 2 This embodiment provides a method for continuously producing isosorbide using the apparatus of embodiment 1. The preparation process is as follows: Figure 2 As shown, the following steps are included: (1) Reaction: Pure sorbitol melted at high temperature enters preheater 1 for preheating at 100°C; the preheated reaction materials enter reactor 2 for dehydration reaction at 160°C under the action of niobium oxide catalyst, and the reacted materials continuously flow out from the upper part of reactor 2, and the isosorbide yield is 86%; (2) Separation: The material from the reactor 1 flows into the shell side of the dehydration tower 5 and exchanges heat with the liquid material after solid impurities are removed in the process to cool it down. After cooling, it enters the sedimentation tank 3. After the solid waste such as the pulverized catalyst is settled in the sedimentation tank 3, the liquid product enters the filter 4 and is filtered under reduced pressure to remove insoluble impurities. The filtrate enters the dehydration tower 5 and is dehydrated and concentrated at 110°C and a vacuum degree of -0.1 to -0.3 MPa. The anhydrous concentrate enters the distillation tower 6 and is heated to 170°C and a vacuum degree of -0.1 MPa to distill out the crude isosorbide. (3) Purification: The crude isosorbide is decolorized in a decolorization tower 7, where the decolorizing agent is activated carbon; after decolorization, it enters a distillation tower 8 for distillation and purification at a bottom temperature of 250°C to obtain isosorbide with a light component as colorless and transparent; the isosorbide enters a crystallization tower 9, where it is recrystallized through ethyl acetate and filtered to obtain high-purity isosorbide colorless crystals with a purity of 99.3%.

[0030] Example 3 This embodiment provides a method for continuously producing isosorbide using the device of embodiment 1, comprising the following steps: (1) Reaction: Pure sorbitol melted at high temperature enters preheater 1 for preheating at 110°C; the preheated reaction materials enter reactor 2 for dehydration reaction at 170°C under the action of niobium oxide catalyst, and the reacted materials continuously flow out from the upper part of reactor 2, and the yield of isosorbide is 91%; (2) Separation: The material from the reactor 1 flows into the shell side of the dehydration tower 5 and exchanges heat with the liquid material after solid impurities are removed in the process to cool it down. After cooling, it enters the sedimentation tank 3. After the solid waste such as the pulverized catalyst is settled in the sedimentation tank 3, the liquid product enters the filter 4 and is filtered under reduced pressure to remove insoluble impurities. The filtrate enters the dehydration tower 5 and is dehydrated and concentrated at 110°C and a vacuum degree of -0.1 to -0.3 MPa. The anhydrous concentrate enters the distillation tower 6 and is heated to 170°C and a vacuum degree of -0.1 MPa to distill out the crude isosorbide. (3) Purification: The crude isosorbide is decolorized in a decolorization tower 7, where the decolorizing agent is activated carbon; after decolorization, it enters a distillation tower 8 for distillation and purification at a bottom temperature of 250°C to obtain isosorbide with a light component as colorless and transparent; the isosorbide enters a crystallization tower 9, where it is recrystallized through ethyl acetate and filtered to obtain high-purity isosorbide colorless crystals with a purity of 99.5%.

[0031] Example 4 This embodiment provides a method for continuously producing isosorbide using the device of embodiment 1, comprising the following steps: (1) Reaction: Pure sorbitol melted at high temperature enters preheater 1 for preheating at 120°C; the preheated reaction materials enter reactor 2 for dehydration reaction at 180°C under the action of niobium oxide catalyst, and the reacted materials continuously flow out from the upper part of reactor 2, and the yield of isosorbide is 96%; (2) Separation: The material from the reactor 1 flows into the shell side of the dehydration tower 5 and exchanges heat with the liquid material after solid impurities are removed in the process to cool it down. After cooling, it enters the sedimentation tank 3. After the solid waste such as the pulverized catalyst is settled in the sedimentation tank 3, the liquid product enters the filter 4 and is filtered under reduced pressure to remove insoluble impurities. The filtrate enters the dehydration tower 5 and is dehydrated and concentrated at 120°C and a vacuum degree of -0.1 to -0.3 MPa. The anhydrous concentrate enters the distillation tower 6 and is heated to 170°C and a vacuum degree of -0.1 MPa to distill out the crude isosorbide. (3) Purification: The crude isosorbide is decolorized in a decolorization tower 7, where the decolorizing agent is activated carbon; after decolorization, it enters a distillation tower 8 for distillation and purification at a bottom temperature of 230°C to obtain isosorbide with a light component as colorless and transparent; the isosorbide enters a crystallization tower 9, where it is recrystallized through ethyl acetate and filtered to obtain high-purity isosorbide colorless crystals with a purity of 99.9%.

[0032] Example 5 This embodiment provides a method for continuously producing isosorbide using the device of embodiment 1, comprising the following steps: (1) Reaction: Pure sorbitol melted at high temperature enters preheater 1 for preheating at 120°C; the preheated reaction materials enter reactor 2 for dehydration reaction at 180°C under the action of catalyst metal phosphoric acid (niobium phosphate), and the reacted materials continuously flow out from the upper part of reactor 2, and the yield of isosorbide is 83%; (2) Separation: The material from the reactor 1 flows into the shell side of the dehydration tower 5 and exchanges heat with the liquid material after solid impurities are removed in the process to cool it down. After cooling, it enters the sedimentation tank 3. After the solid waste such as the pulverized catalyst is settled in the sedimentation tank 3, the liquid product enters the filter 4 and is filtered under reduced pressure to remove insoluble impurities. The filtrate enters the dehydration tower 5 and is dehydrated and concentrated at 120°C and a vacuum degree of -0.1 to -0.3 MPa. The anhydrous concentrate enters the distillation tower 6 and is heated to 170°C and a vacuum degree of -0.1 MPa to distill out the crude isosorbide. (3) Purification: The crude isosorbide is decolorized in a decolorization tower 7, where the decolorizing agent is activated carbon; after decolorization, it enters a distillation tower 8 for distillation and purification at a bottom temperature of 230°C to obtain isosorbide with a light component as colorless and transparent; the isosorbide enters a crystallization tower 9, where it is recrystallized through ethyl acetate and filtered to obtain high-purity isosorbide colorless crystals with a purity of 99.1%.

[0033] It can be seen from Examples 2 to 5 that as the reaction temperature increases, the catalyst efficiency increases and the catalyst resists coking. The increase in reaction temperature is more conducive to the second step dehydration reaction of sorbitol, and the yield of isosorbide increases accordingly.

[0034] Example 6 This embodiment provides a method for continuously producing isosorbide using the device of embodiment 1, comprising the following steps: (1) Reaction: Pure sorbitol melted at high temperature enters preheater 1 for preheating at 120°C; the preheated reaction materials enter reactor 2 for dehydration reaction at 180°C under the action of catalyst polymerized ionic liquid, and the reacted materials continuously flow out from the upper part of reactor 2, and the isosorbide yield is 94%; (2) Separation: The material from the reactor 1 flows into the shell side of the dehydration tower 5 and exchanges heat with the liquid material after solid impurities are removed in the process to cool down. After cooling down, it enters the sedimentation tank 3. After the solid waste such as the pulverized catalyst is settled in the sedimentation tank 3, the liquid product enters the filter 4 and is filtered under reduced pressure to remove insoluble impurities. The filtrate enters the dehydration tower 5 and is dehydrated and concentrated at 120°C and a vacuum degree of -0.1 to -0.3 MPa. The anhydrous concentrate enters the distillation tower 6 and is heated to 170°C and a vacuum degree of -0.1 MPa to distill out the crude isosorbide. (3) Purification: The crude isosorbide is decolorized in a decolorization tower 7, where the decolorizing agent is activated carbon; after decolorization, it enters a distillation tower 8 for distillation and purification at a bottom temperature of 230°C to obtain isosorbide with a light component being colorless and transparent; the isosorbide enters a crystallization tower 9, where it is recrystallized through ethyl acetate and filtered to obtain high-purity isosorbide colorless crystals with a purity of 99.8%.

[0035] Example 7 This embodiment provides a method for continuously producing isosorbide using the device of embodiment 1, comprising the following steps: (1) Reaction: Pure sorbitol melted at high temperature enters preheater 1 for preheating at 120°C; the preheated reaction materials enter reactor 2 for dehydration reaction at 180°C under the action of catalyst molecular sieve, and the reacted materials continuously flow out from the upper part of reactor 2, and the isosorbide yield is 88.2%; (2) Separation: The material from the reactor 1 flows into the shell side of the dehydration tower 5 and exchanges heat with the liquid material after solid impurities are removed in the process to cool down. After cooling down, it enters the sedimentation tank 3. After the solid waste such as the pulverized catalyst is settled in the sedimentation tank 3, the liquid product enters the filter 4 and is filtered under reduced pressure to remove insoluble impurities. The filtrate enters the dehydration tower 5 and is dehydrated and concentrated at 120°C and a vacuum degree of -0.1 to -0.3 MPa. The anhydrous concentrate enters the distillation tower 6 and is heated to 170°C and a vacuum degree of -0.1 MPa to distill out the crude isosorbide. (3) Purification: The crude isosorbide is decolorized in a decolorization tower 7, where the decolorizer is activated carbon; after decolorization, it enters a distillation tower 8 for distillation and purification at a bottom temperature of 230°C to obtain isosorbide with a light component being colorless and transparent; the isosorbide enters a crystallization tower 9, where it is recrystallized through ethyl acetate and filtered to obtain high-purity isosorbide colorless crystals with a purity of 99.5%.

Claims

1. A continuous production device for high-purity isosorbide, characterized in that: It comprises a reaction unit, a separation unit and a purification unit connected in sequence; the reaction unit comprises a preheater and a reactor; the separation unit comprises a sedimentation tank, a filter, a dehydration tower and a distillation tower; the purification unit comprises a decolorization tower, a distillation tower and a crystallization tower.

2. The continuous production device of high-purity isosorbide according to claim 1, characterized in that: The lower discharge port of the preheater is connected to the lower feed port of the reactor; the upper discharge port of the reactor is connected to the upper shell feed port of the dehydration tower, the lower shell feed port of the dehydration tower is connected to the upper feed port of the settling tank, the lower discharge port of the settling tank is connected to the upper feed port of the filter, the lower discharge port of the filter is connected to the lower feed port of the dehydration tower, and the upper discharge port of the dehydration tower is connected to the lower feed port of the distillation tower; the upper discharge port of the distillation tower is connected to the upper feed port of the bleaching tower, the lower discharge port of the bleaching tower is connected to the middle feed port of the distillation tower, and the upper discharge port of the distillation tower is connected to the upper feed port of the crystallization tower; the lower discharge port of the distillation tower and the lower discharge port of the distillation tower are both connected to the upper feed port of the preheater.

3. The continuous production device of high-purity isosorbide according to claim 2, characterized in that: The upper part of the reactor is also provided with a catalyst feed port, the lower part of the reactor is also provided with a waste catalyst discharge port; the lower part of the filter is provided with a solid waste discharge port.

4. A method for continuously producing isosorbide using the device according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Reaction: The sorbitol raw material enters the preheater for preheating. The preheated material enters the reactor for dehydration reaction at 120-200 °C under the action of a catalyst. The reacted material flows out from the discharge port at the top of the reactor. (2) Separation: The reacted material enters the shell side of the dehydration tower for heat exchange and cooling. After cooling, it enters the sedimentation tank to settle the solid waste. The supernatant enters the filter for filtration. The liquid phase flows into the dehydration tower for dehydration and concentration at a temperature of 60 to 130 °C and a vacuum degree of -0.1 to -0.3 MPa. It then enters the distillation tower at a temperature of 150 to 250 °C and a vacuum degree of -0.1 to -0.3 MPa to distill out the crude isosorbide. (3) Purification: The crude isosorbide is purified by a decolorization tower, a distillation tower and a crystallization tower to obtain high-purity isosorbide.

5. The method for continuous production of high-purity isosorbide according to claim 4, characterized in that: The sorbitol raw material is pure sorbitol or sorbitol solution melted at high temperature; the sorbitol solution is an industrial-grade sorbitol solution with a concentration of 30% to 70%.

6. The method for continuous production of high-purity isosorbide according to claim 4 or 5, characterized in that: When the sorbitol raw material is pure sorbitol melted at high temperature, the preheating temperature is 100-130°C; when the sorbitol raw material is sorbitol solution, the preheating temperature is 30-80°C.

7. The method for continuous production of high-purity isosorbide according to claim 4, characterized in that: The temperature of the distillation tower kettle in step (3) is 150-250° C.; the mass ratio of crude isosorbide to crystallization solvent in the crystallization tower is 1:2.5-7.

8. The method for continuous production of high-purity isosorbide according to claim 4, characterized in that: The filter adopts pressure filtration, pressure reduction filtration or centrifugal filtration.

9. The method for continuous production of high-purity isosorbide according to claim 4, characterized in that: The decolorizing agent in the decolorizing tower is activated carbon, clay or resin.

10. The method for continuous production of high-purity isosorbide according to claim 4 or 7, characterized in that: The catalyst is any one of polymerized ionic liquid, niobium oxide, niobium phosphate and molecular sieve, and the crystallization solvent is any one of ethyl acetate, methanol, ethanol and ethylene glycol.

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