Reaction device for preparing isosorbide through two-step dehydration continuous reaction of sorbide

Abstract

The utility model belongs to the field of chemistry and chemical engineering, and particularly relates to a reaction device for preparing isosorbide through two-step dehydration and continuous reaction of sorbide. The device comprises a first-stage dehydration reactor and a second-stage dehydration reactor which are communicated, the upper part of the first-stage dehydration reactor is connected with an inlet pipeline, an outlet of the inlet pipeline extends into the bottom of the reactor, and a discharge port of the first-stage dehydration reactor is connected with a feed port of the second-stage dehydration reactor through a downward inclined connecting pipeline. The outlet of the inlet pipeline of the secondary dehydration reactor extends into the bottom of the reactor; partition plates are arranged in the first-stage dehydration reactor and the second-stage dehydration reactor; each of the first-stage dehydration reactor and the second-stage dehydration reactor is provided with a stirring component; each stirring component comprises motors respectively arranged at the upper ends of the first-stage dehydration reactor and the second-stage dehydration reactor, and stirring paddles which are connected with the lower ends of the motors and extend into the inner cavities of the reactors. According to the utility model, two-step dehydration for preparing isosorbide from sorbitol can be continuously carried out, so that the reaction efficiency and the space-time yield are improved, and the reaction cost is saved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of chemistry and chemical industry, and particularly relates to a sorbitol two-step dehydration continuous reaction preparation isosorbide reaction device. BACKGROUND

[0002] Isosorbide is the only sugar diol that is industrially produced in large quantities, and is widely used in food, cosmetics, medicine, plastic and polymer fields as a new type of bio-based material. In addition, isosorbide can also be used as an intermediate for the synthesis of liquid crystal materials and is widely used in electronic and national defense fields.

[0003] Isosorbide can be prepared from sorbitol, which is dehydrated in two steps under the catalysis of acid to produce isosorbide. Cellulose can also be directly hydrogenated and dehydrated to synthesize isosorbide in one step under the action of a bifunctional catalyst or a composite multifunctional catalyst. At present, the one-step conversion method has low efficiency and low isosorbide yield compared with the two-step dehydration reaction of sorbitol. In addition, the one-step conversion method also has the problems of difficult product purification and short-term industrialization. In industry, concentrated sulfuric acid is mainly used as a catalyst, and a batch kettle reactor is used to prepare isosorbide by two-step dehydration of sorbitol. Liquid acid catalysts have high catalytic activity and good selectivity, but they have the disadvantages of easy corrosion of equipment, non-reusable catalysts and difficult continuous production. Therefore, it is urgent to improve the catalyst system and establish a continuous production process for isosorbide. In order to solve the technical problem, solid acid catalysts and the corresponding reaction process for preparing isosorbide by solid acid catalytic dehydration of sorbitol have been developed, but there is no continuous production reactor suitable for solid acid catalytic reaction. SUMMARY

[0004] In view of the problems and deficiencies in the prior art, the purpose of the utility model is to provide a sorbitol two-step dehydration continuous reaction preparation isosorbide reaction device.

[0005] Based on the above purpose, the utility model adopts the following technical scheme:

[0006] The utility model provides a kind of sorbitol two-step dehydration continuous reaction preparation isosorbide reaction device, including intercommunication's first dehydration reactor and secondary dehydration reactor, the first dehydration reactor upper portion is connected with import pipeline, import pipeline outlet extends into reactor bottom, the discharge outlet of the first dehydration reactor is connected with the feed inlet of secondary dehydration reactor by inclined downward connecting pipeline, the import pipeline outlet of secondary dehydration reactor extends into reactor bottom, the discharge outlet of the first dehydration reactor is higher than the feed inlet of secondary dehydration reactor;The first dehydration reactor and secondary dehydration reactor inside are each equipped with baffle;The first dehydration reactor and secondary dehydration reactor are each equipped with stirring member, and the stirring member includes motor respectively arranged in the upper end of the first dehydration reactor and secondary dehydration reactor, the lower end of the motor is connected with the stirring paddle that extends into the reactor inner chamber, and the stirring shaft passes the hole in the center of baffle;Auxiliary feed pipe orifice is set in the top of the dehydration reactor.

[0007] Further, the import pipeline of the first dehydration reactor and the outlet pipeline of secondary dehydration reactor enter dehydration reactor horizontally.

[0008] Further, the connecting pipeline connecting the discharge outlet of the first dehydration reactor and the feed inlet of secondary dehydration reactor is inclined downward by 10-15 degrees.

[0009] Further, the number of baffles of the first dehydration reactor is 3-5, and the number of baffles of secondary dehydration reactor is 4-7;Square holes are uniformly arranged on the baffles;The stirring paddle is placed between two layers of baffles.

[0010] Further, the design form of the stirring paddle is a blade type paddle.

[0011] Further, the ratio of the aperture diameter of the stirring paddle of the first dehydration reactor to the reactor diameter is 0.15-0.35, and the ratio of the aperture diameter of the stirring paddle of secondary dehydration reactor to the reactor diameter is 0.1-0.3.

[0012] Further, the height-diameter ratio of the first dehydration reactor is 1.5-3, and the height-diameter ratio of secondary dehydration reactor is 2-4.

[0013] Further, the opening rate of the baffle of the first dehydration reactor is 28%-33%, and the opening rate of the baffle of secondary dehydration reactor is 18%-23%.

[0014] Further, the square hole of the baffle is close to the inner side wall side of the first dehydration reactor and secondary dehydration reactor.

[0015] Further, the dehydration reactor top is also provided with inlet and outlet valves and vacuum valves.

[0016] The use process of the reaction device is as follows: sorbitol enters the first-stage dehydration reactor through the inlet pipeline, and, under the action of the stirring paddle driven by the motor, the sorbitol completes the first-stage dehydration and then enters the second-stage dehydration reactor through the reactor connecting pipeline, and, under the action of the stirring paddle driven by the motor, the isosorbide generated after the completion of the second-stage dehydration is discharged from the reaction device through the outlet pipeline.

[0017] The temperature of the first-stage dehydration reactor is 120-150 o C, the pressure is -0.01 to -0.05 MPa, and the residence time is 3-4 h; the temperature of the second-stage dehydration reactor is 150-190 o C, the pressure is -0.05 to -0.1 MPa, and the residence time is 2-3 h.

[0018] Compared with the prior art, the reaction device has the following beneficial effects:

[0019] (1) The reaction device can continuously perform the two-stage dehydration of sorbitol to isosorbide, fully reacts under the action of the stirring paddle, realizes continuous feeding and discharging, improves the reaction efficiency and the space-time yield, and saves the reaction cost.

[0020] (2) Compared with the batch reactor and the kettle type continuous reactor, the reaction device has the best comprehensive conversion rate in the comprehensive conversion rate, and the comprehensive conversion rate can reach 100%; and the yield of the reaction device is the highest in the isosorbide yield, and the yield is 85%.

[0021] (3) The reaction device can be used for continuous production, and has the advantages of the batch reactor and the kettle type continuous reactor. The reaction device is superior to the other two reactors in the comprehensive conversion rate and the yield, and improves the reaction efficiency and the product yield. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structure schematic view of the reaction device for preparing isosorbide through two-stage dehydration of sorbitol according to the utility model;

[0023] Figure 2 is a top view structure schematic view of the reaction device for preparing isosorbide through two-stage dehydration of sorbitol according to the utility model.

[0024] In the drawing: 1 - first-stage dehydration reactor; 2 - baffle; 3 - stirring paddle; 4 - inlet pipeline; 5 - outlet pipeline; 6 - motor; 7 - square hole; 8 - feed pipe perforation; 9 - second-stage dehydration reactor. DETAILED DESCRIPTION

[0025] The utility model will be explained below in detail, and the technical solutions in the embodiments of the utility model will be clearly and completely described. Obviously, the described embodiments are only some of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the utility model.

[0026] Embodiment 1

[0027] A sorbitol two-step dehydration continuous reaction preparation isosorbide reaction device, the schematic diagram is as shown in Figure 1 And Figure 2 The first dehydration reactor 1 is connected with the inlet pipeline 4 at the upper portion, the outlet of the inlet pipeline 4 extends into the bottom of the reactor, the outlet of the first dehydration reactor 1 is connected with the inlet of the second dehydration reactor 9 through the connecting pipeline inclined downward by 10-15 degrees, the inlet pipeline outlet of the second dehydration reactor 9 extends into the bottom of the reactor, and the outlet of the first dehydration reactor 1 is higher than the inlet of the second dehydration reactor 9.

[0028] The first dehydration reactor 1 and the second dehydration reactor 9 are internally provided with the baffle 2, the baffle 2 is also called the flow baffle, and the back mixing and penetration are reduced; the first dehydration reactor 1 and the second dehydration reactor 9 are provided with the stirring member, the stirring member comprises the motor 6 arranged at the upper end of the first dehydration reactor 1 and the second dehydration reactor 9 respectively, the lower end of the motor 6 is connected with the stirring paddle 3 extending into the cavity of the reactor, the stirring shaft passes through the hole in the center of the baffle 2, and the stirring paddle 3 is arranged between the two layers of baffles 2; the dehydration reactor is provided with the auxiliary inlet pipe and the inlet pipe perforation 8 at the top portion, and the dehydration reactor is further provided with the inlet and outlet valves and the vacuum valve.

[0029] The first dehydration reactor 1 is provided with 3-5 baffles 2, and the second dehydration reactor 9 is provided with 4-7 baffles 2. The square holes 7 are uniformly arranged on the baffles 2, and the square holes 7 of the baffles 2 are close to the inner side walls of the first dehydration reactor 1 and the second dehydration reactor 9. The opening rate (area ratio) of the baffles 2 of the first dehydration reactor 1 is 28%-33%, and the opening rate (area ratio) of the baffles 2 of the second dehydration reactor 9 is 18%-23%. The ratio of the opening diameter of the stirring paddle 3 of the first dehydration reactor 1 to the diameter of the reactor is 0.15-0.35, and the ratio of the opening diameter of the stirring paddle 3 of the second dehydration reactor 9 to the diameter of the reactor is 0.1-0.3.

[0030] In production, sorbitol solution and catalyst are introduced into the first dehydration reactor 1 through the inlet pipe 4, and the first dehydration reaction is carried out under the action of the stirring paddle 3 driven by the motor 6. The temperature of the first dehydration reactor 1 is controlled at 135 o C, the pressure is -0.03 MPa, and the residence time is 3.5 h. After the completion of the first dehydration reaction of sorbitol, the sorbitol is introduced into the second dehydration reactor 9 through the reactor connecting pipe. The second dehydration reaction is carried out under the action of the stirring paddle 3 driven by the motor 6. The temperature of the second dehydration reactor 9 is controlled at 170 o C, the pressure is -0.07 MPa, and the residence time is 2.5 h. After the completion of the second dehydration reaction, the isosorbide generated is discharged from the reaction device through the outlet pipe 5. The conversion rate of sorbitol and the yield of isosorbide are calculated, and the results are shown in Table 1.

[0031] Comparative Example 1

[0032] A batch reactor for preparing isosorbide is used in production. Sorbitol and catalyst are loaded into the reactor. The first step of dehydration is carried out in the reactor. Sorbitol is dehydrated by the first reaction at 150°C to obtain a first product, which includes 1,4-anhydrosorbitol and isosorbide. Then the second step of dehydration is carried out. The temperature is kept at 150°C, and 1,4-anhydrosorbitol is dehydrated by the second reaction to generate isosorbide, and a gaseous mixture of isosorbide and water is simultaneously evaporated. Isosorbide is separated from the gaseous mixture. The gaseous mixture is introduced into a condensation system, and the liquid product after condensation is collected in a container. Then the product is purified to improve the purity of isosorbide. The conversion rate of sorbitol and the yield of isosorbide are calculated, and the results are shown in Table 1.

[0033] Comparative Example 2

[0034] A kettle-type continuous reactor (without internal components) for preparing isosorbide is used in production. Sorbitol solution and catalyst are mixed, and the material is melted by heating in a stirred kettle to 80°C. After the reactor is preheated to 150°C, the material enters the reactor, and the reaction is carried out at 160°C and 10 kpa. After the reaction, the material enters a separation unit, and the crude isosorbide is separated at 150°C and 30 kpa. The crude isosorbide is condensed by a condenser and enters a crystallization separator. After filtration and drying, isosorbide with high purity is obtained. The whole process can realize continuous and rapid separation of catalyst and product, and improve the yield and purity of isosorbide. The conversion rate of sorbitol and the yield of isosorbide are calculated, and the results are shown in Table 1.

[0035] Table 1 Conversion rate of sorbitol and yield of isosorbide in different solid acid catalytic reactor types

[0036]

[0037] Note: Conversion rate, yield: conversion rate and yield under continuous operation conditions after recycling of unreacted raw materials

[0038] From Table 1, in terms of single-pass conversion rate, the batch reactor has the highest conversion rate, reaching 99%. The single-pass conversion rate of the reactor of the present application is between 67% and 69%, while the single-pass conversion rate of the tank continuous reactor is between 54% and 56%. In terms of comprehensive conversion rate, the reactor of the present application performs best, reaching 100%, followed by the batch reactor and the tank continuous reactor, which are 99% and 99%, respectively. In terms of isosorbide yield, the reactor of the present application has the highest yield, which is 85%, followed by the batch reactor, which is 80%, while the comprehensive yield of the tank continuous reactor is 73%.

[0039] The batch reactor performs best in terms of single-pass conversion rate, but the reactor of the present application performs better in terms of comprehensive conversion rate and yield, showing higher efficiency and yield. Although the tank continuous reactor has a lower single-pass conversion rate, its comprehensive conversion rate and yield can also reach a high level in terms of conversion rate and yield under continuous operation conditions, indicating that it has certain advantages in continuous production. The reactor of the present application can be continuously produced, combining the advantages of the batch reactor and the tank continuous reactor, and performs better than the other two reactors in terms of comprehensive conversion rate and yield, improving the reaction efficiency and product yield.

[0040] Although the description of the present application is made in combination with the above specific embodiments, it is obvious for those skilled in the art to make many substitutions, modifications and changes according to the above content. Therefore, all such substitutions, improvements and changes should belong to the protection scope of the claims of the present application.

Claims

1. An apparatus for the two-step dehydration and continuous reaction of sorbitol to prepare isosorbitol, characterized in that, The device comprises a communication first-stage dewatering reactor and a second-stage dewatering reactor, the first-stage dewatering reactor is connected with an inlet pipeline at the upper part, the outlet of the inlet pipeline extends into the bottom of the reactor, the outlet of the first-stage dewatering reactor is connected with the inlet of the second-stage dewatering reactor through an inclined downward connecting pipeline, the inlet pipeline of the second-stage dewatering reactor extends into the bottom of the reactor, the outlet of the first-stage dewatering reactor is higher than the inlet of the second-stage dewatering reactor; the first-stage dewatering reactor and the second-stage dewatering reactor are both internally provided with a baffle; the first-stage dewatering reactor and the second-stage dewatering reactor are both provided with a stirring member, the stirring member comprises a motor arranged at the upper end of the first-stage dewatering reactor and the second-stage dewatering reactor respectively, the lower end of the motor is connected with a stirring paddle extending into the inner cavity of the reactor, and the stirring shaft passes through the hole in the center of the baffle; the top of the dewatering reactor is provided with an auxiliary feeding pipe.

2. The reaction device for the two-step continuous reaction of sorbitol dehydration to prepare isosorbide according to claim 1, characterized in that, The connecting pipeline connecting the outlet of the first-stage dewatering reactor with the inlet of the second-stage dewatering reactor is inclined downward by 10-15 degrees.

3. The reaction device for the two-step continuous reaction of sorbitol dehydration to prepare isosorbide according to claim 1, characterized in that, The number of baffles of the first-stage dewatering reactor is 3-5, and the number of baffles of the second-stage dewatering reactor is 4-7; the baffles are uniformly arranged with square holes; the stirring paddle is arranged between two layers of baffles.

4. The reaction device for the two-step continuous reaction of sorbitol dehydration to prepare isosorbide according to claim 1, characterized in that, The ratio of the opening diameter of the stirring paddle of the first-stage dewatering reactor to the diameter of the reactor is 0.15-0.35, and the ratio of the opening diameter of the stirring paddle of the second-stage dewatering reactor to the diameter of the reactor is 0.1-0.

3.

5. The reaction device for the two-step continuous reaction of sorbitol dehydration to produce isosorbide according to claim 1, characterized in that, The height-diameter ratio of the first-stage dewatering reactor is 1.5-3, and the height-diameter ratio of the second-stage dewatering reactor is 2-4.

6. The sorbitol two-step dehydrating continuous reaction reaction device for preparing isosorbide according to claim 3, characterized in that, The opening rate of the baffle of the first-stage dewatering reactor is 28%-33%, and the opening rate of the baffle of the second-stage dewatering reactor is 18%-23%.

7. The sorbitol two-step dehydrating continuous reaction reaction device for preparing isosorbide according to claim 6, characterized in that, The square holes of the baffles are close to the inner side wall of the first-stage dewatering reactor and the second-stage dewatering reactor.

8. The reaction device for the two-step continuous reaction of sorbitol dehydration to prepare isosorbide according to claim 1, characterized in that, The top of the dewatering reactor is further provided with an air inlet and outlet valve and a vacuum valve.

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