CN112934148A - Reaction system and method for oligomerization of lactic acid - Google Patents
Reaction system and method for oligomerization of lactic acid Download PDFInfo
- Publication number
- CN112934148A CN112934148A CN201911172939.5A CN201911172939A CN112934148A CN 112934148 A CN112934148 A CN 112934148A CN 201911172939 A CN201911172939 A CN 201911172939A CN 112934148 A CN112934148 A CN 112934148A
- Authority
- CN
- China
- Prior art keywords
- reaction
- oligomerization
- lactic acid
- kettle
- tower
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/18—Stationary reactors having moving elements inside
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/322—Reboiler specifications
Abstract
The invention provides a reaction system and a method for oligomerization of lactic acid. The reaction system comprises: the lactic acid oligomerization reaction kettle and the reaction rectifying tower are connected in sequence; the reaction rectifying tower comprises a tower kettle reboiler, a rectifying section and a deep oligomerization dehydration reaction section, wherein the rectifying section and the deep oligomerization dehydration reaction section are arranged from top to bottom; a first feeding hole is formed in a tower section between the rectifying section and the deep oligomerization dehydration reaction section and is used for introducing a product of the lactic acid oligomerization reaction kettle into the reaction rectifying tower; and a tower kettle of the reaction rectifying tower is provided with a first discharge port, a product discharged from the first discharge port is heated by the tower kettle reboiler, one part of the product returns to the deep oligomerization dehydration reaction section again, and the other part of the product is directly collected. The reaction system provided by the invention integrates rectification and deep oligomerization dehydration reaction, optimizes the reaction route, improves the reaction separation efficiency, realizes the effect of timely removing water in the reaction system, and avoids the existence of water to dilute the reaction materials.
Description
Technical Field
The invention relates to the field of lactic acid oligomerization preparation, and particularly relates to a reaction system and a method for lactic acid oligomerization.
Background
The production and exploitation of lactide has gained increasing attention in recent years, mainly because the ring-opening polymerization of lactide is an efficient method for preparing high molecular weight polylactic acid. Polylactic acid is a biodegradable material with a great development prospect, and is an excellent medical high polymer material because the final products decomposed in the natural environment are carbon dioxide and water, so that the polylactic acid is nontoxic and harmless to the environment, and has the advantages of good biocompatibility and biodegradability, excellent mechanical property, easiness in processing and forming and the like. The ring-opening polymerization reaction of lactide is an effective method for preparing high-molecular-weight polylactic acid, and the molecular weight of the polylactic acid of a polymerization product can reach millions.
The existing lactide generation process comprises the following steps:
(1) oligomerization reaction: the lactic acid is subjected to multistage esterification reaction under certain temperature and pressure conditions, and is dehydrated and polycondensed into oligomer;
(oligomers are mixtures of components with a degree of polymerization of 1 to 30(P1-P30) with gradually increasing boiling points, in which the mixture is replaced by P15)
(2) And (3) synthesis reaction: under certain temperature and pressure conditions, the oligomer is thermally decomposed and broken to form lactide.
Wherein, the oligomerization reaction process of the first step is lactic acid intermolecular dehydration, and because the oligomerization reaction is a reversible reaction, the existence of water can dilute reaction materials and influence the reaction rate, thereby influencing the normal operation of the reaction process.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The first purpose of the invention is to provide a reaction system for oligomerization of lactic acid, which integrates rectification and deep oligomerization dehydration reaction, optimizes the reaction route, improves the reaction separation efficiency, realizes the effect of timely removing water in the reaction system, avoids the reaction material dilution caused by the presence of water to influence the reaction process, further improves the quality and yield of the oligomerization product, and plays the roles of saving the equipment cost and the floor area of the equipment, thereby achieving two purposes.
The second purpose of the invention is to provide a reaction method for carrying out lactic acid oligomerization by adopting the reaction system, and the lactic acid oligomer product obtained by the reaction has good quality and high yield.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
the invention provides a reaction system for oligomerization of lactic acid, which comprises: the lactic acid oligomerization reaction kettle and the reaction rectifying tower are connected in sequence;
the reaction rectifying tower comprises a tower kettle reboiler, a rectifying section and a deep oligomerization dehydration reaction section, wherein the rectifying section and the deep oligomerization dehydration reaction section are arranged from top to bottom;
a first feeding hole is formed in a tower section between the rectifying section and the deep oligomerization dehydration reaction section and is used for introducing a product of the lactic acid oligomerization reaction kettle into the reaction rectifying tower;
and a tower kettle of the reaction rectifying tower is provided with a first discharge port, and after a product discharged from the first discharge port is heated by the tower kettle reboiler, one part of the product returns to the deep oligomerization dehydration reaction section again, and the other part of the product is directly collected.
In the prior art, the oligomerization reaction process is lactic acid intermolecular dehydration, the reaction is reversible, the reaction rate is influenced by the presence of water, reaction materials are diluted, and the reaction process is restricted because the water in the oligomerization reaction system cannot be removed in time; meanwhile, more residual water is left in the materials, so that the efficiency of the synthesis reaction kettle is reduced, and therefore, water in a reaction system needs to be quickly extracted, and the reaction equilibrium is carried out towards the polymerization direction.
In order to solve the technical problems, the deep oligomerization dehydration reaction section is specially arranged in the reaction rectifying tower, so that the problem of incomplete reaction of the lactic acid oligomerization reaction kettle is solved, water is timely removed through the rectifying section after oligomerization reaction in the reaction rectifying tower, the problem that reaction materials are diluted by water to influence the reaction process is avoided, and the quality and the yield of an oligomerization product are improved.
In the lactic acid oligomerization reaction process, the obtained product is oligomer with the polymerization degree of 1-30, the polymerization degree is an important index for measuring the molecular size of the polymer, and the average value of the number of the repeating units contained in the macromolecular chain of the polymer is based on the number of the repeating units, and the repeating units are lactic acid molecules.
For convenience of the present invention, the symbol P indicates that P1-P30 means a polymerization degree of 1-30, for example, P15 means a polymerization of 15 lactic acid molecules.
The bottoms of reactive distillation columns are mostly oligomers with high density such as P29 and P30 in polymerization degree, and a bottom reboiler is arranged in the bottoms to prevent solidification.
After being heated by a reboiler at the tower bottom, one part of products returns to the reaction rectifying tower for further rectifying reaction, and the other part of products is directly extracted as products and is directly used as raw materials for synthesizing lactide after certain post-treatment steps.
Preferably, as a further implementable scheme, the tower kettle reboiler is a falling film reboiler, a second feed inlet is formed in the top of the falling film reboiler, a second discharge outlet is formed in the bottom of the falling film reboiler, the second feed inlet is communicated with the first discharge outlet, one part of substances discharged from the second discharge outlet is introduced into the deep oligomerization and dehydration reaction section to continue oligomerization, the other part of the substances is directly collected, and the substances are further reacted and synthesized as the raw material of the lactide after subsequent post-treatment steps.
The reboiler in the tower kettle is selected as the falling film reboiler, and compared with the reboiler in the common type, the reboiler in the type has the advantages that the film is formed on the tube wall, the heat exchange efficiency is high, the residence time is short, the coking is not easy to occur, and the generation of byproducts due to the polymerization of substances in the tower kettle is avoided. And because of the falling film reboiler, the material needs to be fed from the top and discharged from the bottom of the reboiler to improve the evaporation efficiency.
Preferably, as a further implementable scheme, a raw material inlet and a reaction product outlet are arranged on the lactic acid oligomerization reaction kettle, the raw material inlet comprises a lactic acid inlet, and the reaction product outlet is arranged at the bottom of the lactic acid oligomerization reaction kettle;
and the reaction product outlet is communicated with the first feed inlet on the reaction rectifying tower.
The invention can realize the polymerization of lactic acid to form oligomer through the oligomerization reaction in the lactic acid oligomerization reaction kettle.
The generated oligomer is mainly gathered at the bottom of the lactic acid oligomerization reaction kettle with high density, so that the reaction product outlet is arranged at the bottom of the kettle, and the lactic acid inlet is arranged on the side wall of the kettle.
Preferably, as a further implementable scheme, a first conveying pump is arranged on a pipeline for communicating the second feeding hole with the first discharging hole so as to facilitate conveying.
Likewise, as a further practical solution, a second delivery pump is provided on the conduit where the reaction product outlet communicates with the first feed port, also for convenience of delivery.
The specific type of the transfer pump is not limited, the vacuum pump can also meet the process requirements according to the specific requirements, the cost is low, and the occupied area is small.
Preferably, as a further implementable scheme, a pipeline connecting the reaction product outlet and the first feed inlet is further provided with a circulating pipeline for returning a part of substances discharged from the reaction product outlet to the lactic acid oligomerization reaction kettle, and the circulating pipeline is provided with a heat exchanger.
The heat exchanger is arranged on the circulating pipeline, the reaction temperature of the lactic acid oligomerization reaction kettle is controlled in a material circulation mode, the heating of materials can be realized by introducing steam when the temperature is lower, the cooling of the materials can be realized by introducing condensed water when the temperature is higher, the heat exchanger is arranged on the circulating pipeline, and the effect of controlling the reaction temperature in the kettle of the lactic acid oligomerization reaction kettle can be mainly played.
In the present invention, the type of the heat exchanger is not particularly limited, and may be a floating head type heat exchanger, a fixed tube-plate type heat exchanger, a U-shaped tube-plate type heat exchanger, a plate type heat exchanger, or the like.
The tubular heat exchanger is preferred, the material passes through a tube pass, and the heat exchange medium passes through a shell pass, because the structure of the heat exchanger is simpler and more compact, and the manufacturing cost is lower.
Preferably, as a further implementable aspect, the lactic acid oligomerization reaction kettle is a jacketed stirred reaction kettle. The temperature of the oligomerization reaction is about 140 ℃, so the reaction kettle needs to be heated by introducing steam into a jacket.
In addition, in order to enhance the progress of the oligomerization reaction, a stirrer may be disposed in the reaction vessel, and the stirrer may be a propeller stirrer, an anchor stirrer, a turbine stirrer, or the like, wherein the propeller stirrer has the simplest structure, and the propeller stirrer may be classified into a flat propeller stirrer and a slanted propeller stirrer according to the shape of the blades. The flat paddle type stirrer generates radial force, the inclined paddle type stirrer generates axial force, and the paddle type stirrer is suitable for stirring low-viscosity liquid, suspension liquid and dissolved liquid.
The paddle stirrer of the present invention is preferably a paddle stirrer with three flat paddles because the stirrer of this configuration is relatively uniform with respect to stirring.
Preferably, as a further practicable scheme, the top of the reactive distillation column is provided with an overhead condenser for refluxing condensation of water, lactic acid and oligomers distilled from the top of the column to enhance the distillation reaction operation.
The invention also provides a lactic acid oligomerization reaction method, which comprises the following steps:
(A) the lactic acid enters the lactic acid oligomerization reaction kettle to react to generate oligomer;
(B) and (4) feeding the oligomer into a reaction rectifying tower for deep dehydration and oligomerization, and rectifying to obtain a final product.
Preferably, as a further implementable scheme, in the step (A), the reaction temperature is between 100 ℃ and 200 ℃, preferably 130 ℃ and 150 ℃, more preferably the reaction temperature is 140 ℃, and the pressure is 0.05 MPa.
Preferably, as a further implementable scheme, in the step (B), the temperature of the rectification reaction is controlled between 100 and 200 ℃, more preferably between 130 and 170 ℃, preferably 150 ℃, and the pressure is negative pressure, and the specific degree of the negative pressure is not limited at all as long as the negative pressure is negative pressure.
The oligomer product prepared by the lactic acid oligomerization reaction method has good quality and high yield, avoids the influence of moisture on the oligomerization product, and fully realizes the quick discharge of the water generated in the reaction process.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the lactic acid oligomerization reaction system, rectification and oligomerization reaction are integrated uniformly, so that the reaction route is optimized, the reaction separation efficiency is improved, and the quality and yield of products are improved;
(2) the reaction system for oligomerization of lactic acid has the advantages of simple structure, less three wastes, realization of full recycling of raw materials and small occupied area;
(3) according to the invention, the circulating pipeline and the heat exchanger are arranged, so that the effect of controlling the reaction temperature in the lactic acid oligomerization reaction kettle is realized;
(4) the tower kettle reboiler is a falling film reboiler, so that the heat exchange efficiency is improved, and the by-product generation caused by the polymerization of the substances in the tower kettle is avoided;
(5) the reaction system provided by the invention realizes the effect of timely removing water in the reaction system, avoids the problem that the reaction process is influenced by dilution of reaction materials in the presence of water, and further improves the quality and yield of oligomeric products.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 is a schematic structural diagram of a reaction system for oligomerization of lactic acid according to an embodiment of the present invention.
Description of the drawings:
a 100-lactic acid oligomerization reaction kettle; a 110-lactic acid inlet;
130-a reaction product outlet; 140-a second delivery pump;
150-a circulation conduit; 160-heat exchanger.
200-a reactive distillation column; 210-a rectification section;
220-deep oligomerization dehydration reaction section; 230-a first feed port;
240-first discharge hole; 250-column kettle reboiler;
251-a second feed port; 252-a second discharge port;
260-a first delivery pump;
270-overhead condenser.
Detailed Description
The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and the detailed description, but those skilled in the art will understand that the following described embodiments are some, not all, of the embodiments of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In order to more clearly illustrate the technical solution of the present invention, the following description is made in the form of specific embodiments.
Examples
Referring to fig. 1, the reaction system for oligomerization of lactic acid according to the embodiment of the present invention includes two main apparatus bodies, namely, a lactic acid oligomerization reaction kettle 100 and a reaction rectification column 200, which are connected in sequence, wherein the reaction rectification column 200 includes a column kettle reboiler 250, a column top condenser 270, and a rectification section 210 and a deep oligomerization dehydration reaction section 220 arranged from top to bottom;
wherein, the lactic acid oligomerization reaction kettle 100 is provided with a raw material inlet and a reaction product outlet 130, and the raw material inlet is a lactic acid inlet 110.
The first material outlet 240 is arranged at the bottom of the reaction rectifying tower 200, and the first material inlet 230 is arranged on the tower sections of the rectifying section 210 and the deep oligomerization dehydration reaction section 220.
The reaction product outlet 130 on the lactic acid oligomerization reaction kettle 100 is communicated with the first feed inlet 230 on the reactive distillation column 200, and for the convenience of transportation, a second transfer pump 140 is further disposed on the communicated pipeline for providing power to transport oligomers generated by the lactic acid oligomerization reaction kettle 100 to the reactive distillation column 200 for further reaction and separation.
In addition, a branch of a circulation pipeline 150 is connected to a pipeline through which the reaction product outlet 130 on the lactic acid oligomerization reaction kettle 100 is communicated with the first feed inlet 230, a heat exchanger 160 is arranged on the circulation pipeline 150, the heat exchanger 160 is a tube type heat exchanger, the material passes through a tube pass, a heat exchange medium passes through a shell pass, and the material after heat exchange is introduced into the lactic acid oligomerization reaction kettle again through the arrangement of the circulation pipeline 150 and the heat exchanger 160, so as to realize temperature control of the lactic acid oligomerization reaction kettle.
In short, a part of the oligomers generated from the lactic acid oligomerization reaction kettle 100 is returned to the kettle again through the circulation pipeline 150, and the other part enters the reactive distillation column 200 for further reactive distillation.
The lactic acid oligomerization reaction kettle 100 is a stirring reaction kettle with a jacket, steam is introduced into the jacket to control the reaction temperature to be 140 ℃, the pressure to be 0.05MPa, and a paddle type stirrer with three flat paddles is selected as the stirrer to improve the stirring force of the reaction.
In addition, the still reboiler 250 included in the other main equipment reaction rectification column 200 is a falling film reboiler, which has high efficiency and avoids the generation of byproducts. The top of the falling film reboiler is provided with a second feed inlet 251, the bottom of the falling film reboiler is provided with a second discharge outlet 252, and the second feed inlet 251 is communicated with the first discharge outlet 240 on the reaction rectifying tower, so that a part of the product discharged from the first discharge outlet 240 is returned to the deep oligomerization and dehydration reaction section 220 after being heated by the tower kettle reboiler 250, and the other part is directly collected.
A first delivery pump 260 is further disposed on a pipeline connecting the second feed opening 251 and the first discharge opening 240 for convenient transportation.
The material from the reactive distillation column 200 mainly contains oligomers, unreacted raw materials, water, etc., and after entering the reactive distillation column, volatile components of water, lactic acid and a small amount of oligomers gradually accumulate at the top of the column, while the bottom is oligomers having a relatively high density of P1 to P30.
The rectifying section 210 and the deep oligomerization and dehydration reaction section 220 of the reactive rectifying tower 200 are mainly composed of trays and fillers, and the types of the fillers can be Raschig rings, pall rings, step rings and the like. The deep oligomerization reaction section 220 is mainly composed of trays, and may not be added with a filler.
Although the pressure drop of the packing per se is relatively low, the packing has the defect of easy fouling, so that the tower section which is easy to foul is preferably in a tower plate mode.
The top of the reactive distillation column 200 is provided with a top condenser, the components of the top of the column mainly comprise water, lactic acid and a small amount of oligomers, one part of the components flows back to the reactive distillation column 200 through the top condenser 270, and the other part of the components flows out from the top condenser 270 and is recycled.
The distillation reaction temperature in the reactive distillation column 200 is 150 ℃ and the pressure is negative pressure.
In the above-described embodiment, the type of the heat exchanger 160 may also be a floating head heat exchanger, a fixed tube-plate heat exchanger, a U-shaped tube-plate heat exchanger, a plate heat exchanger, or the like.
In the above embodiment, the heating manner of the lactic acid oligomerization reaction kettle 100 may also be a manner of arranging heating pipes on the outer wall of the reaction kettle instead of the jacket, and the type of the stirrer is not limited to three flat paddles, and may be a single flat paddle, two flat paddles, etc., and the type of the stirrer may also be a propeller stirrer, an anchor stirrer, a turbine stirrer, etc.
In the above embodiment, the number of the pump bodies is not specifically required, and the pump bodies may be arranged at corresponding positions as required.
In the above embodiment, the rectifying section 210 and the deep oligomerization and dehydration reaction section 220 of the reactive rectifying tower 200 are only a preferable configuration, and may be increased or decreased according to the actual rectifying effect, for example, it is also feasible to additionally add some rectifying sections.
In the above embodiment, the reaction temperature in the lactic acid oligomerization reaction vessel 100 may be 130 ℃, 135 ℃, 145 ℃, 150 ℃ or the like, and the reaction pressure may be 0.03MPa, 0.04MPa, 0.06MPa, 0.07MPa or the like.
Similarly, the temperature in the reactive distillation column 200 may be 130 ℃, 135 ℃, 145 ℃, 150 ℃ or the like.
In addition, the height, diameter, number of plates, and division of the column section of the reactive distillation column 200 can be adjusted according to actual needs.
The operation and principle of the reaction system for lactic acid oligomerization according to the present invention are briefly described as follows:
firstly, after nitrogen purges pipelines of the lactic acid oligomerization reaction kettle 100, the reaction rectifying tower 200 and the interior of the reaction kettle, lactic acid raw materials are introduced into the lactic acid oligomerization reaction kettle 100 according to a proportion, stirring is carried out while a stirring device of the lactic acid oligomerization reaction kettle is started, the reaction temperature is controlled at 140 ℃, the reaction pressure is 0.05MPa, and oligomers are gradually gathered at the bottom of the kettle along with the progress of the reaction.
One part of the oligomers generated at the bottom of the reaction kettle is conveyed into the reaction rectifying tower 200 through a pipeline, the other part of the oligomers is circulated through a circulating pipeline 150, a heat exchanger 160 is arranged on the circulating pipeline 150, and the reaction temperature in the lactic acid oligomerization reaction kettle is controlled by heating and cooling the oligomers flowing through the circulating pipeline 150.
The generated oligomer and unreacted raw materials enter the deep oligomerization dehydration reaction section 220 from the middle section of the reaction rectifying tower 200 through a pipeline to carry out deep oligomerization dehydration reaction. The operation pressure of the reactive distillation column 200 is negative pressure, and the temperature at the bottom of the column is about 150 ℃.
After deep oligomerization and dehydration reaction, the generated oligomers P1-P30 with high boiling point gradually gather at the bottom of the tower, volatile components of lactic acid, a small amount of oligomers and water are separated to the top of the tower through a rectifying section 210, one part of the volatile components of lactic acid, a small amount of oligomers and water are refluxed through a top condenser 270, the other part of the volatile components of lactic acid, a small amount of oligomers and water are discharged through the top condenser 270, and the volatile components of lactic acid, the.
In addition, unreacted raw materials and other substances are still in the oligomer at the bottom of the tower after the deep oligomerization dehydration reaction, and after part of the oligomer passes through a tower kettle reboiler 250 of the tower kettle, the oligomer is subjected to cyclic deep reaction rectification at the tower kettle, and the other part of oligomer is extracted and post-treated to be used as a subsequent synthetic raw material of lactide.
The tower reboiler 250 is a falling film reboiler, and the material enters from the top of the tower reboiler 250 and returns to the reactive distillation column 200 from the bottom of the tower reboiler 250 after being evaporated.
For the convenience of control, a valve is correspondingly arranged on a pipeline of the reaction process system, the type of the valve can be a ball valve, a butterfly valve and the like, and an electromagnetic valve can also be adopted as an important control point.
The above steps are repeated circularly to make the whole reaction system run smoothly.
By adopting the lactic acid oligomerization reaction mode, the conversion rate of raw materials is increased by 10-20% compared with the prior art, the yield of oligomers is correspondingly improved compared with the prior art, and the effects of reducing energy consumption and improving the conversion rate of the raw materials and the yield of products can be achieved.
Compared with the lactic acid oligomerization reaction system in the prior art, the reaction system has the advantages of fewer equipment components, small occupied area, low energy consumption, low cost, controllable reaction and high raw material conversion rate, provides a lactic acid oligomerization reaction system with stronger operability for the subsequent preparation of lactide, and is worthy of wide popularization and application.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A reaction system for oligomerization of lactic acid, comprising: the lactic acid oligomerization reaction kettle and the reaction rectifying tower are connected in sequence;
the reaction rectifying tower comprises a tower kettle reboiler, a rectifying section and a deep oligomerization dehydration reaction section, wherein the rectifying section and the deep oligomerization dehydration reaction section are arranged from top to bottom;
a first feeding hole is formed in a tower section between the rectifying section and the deep oligomerization dehydration reaction section and is used for introducing a product of the lactic acid oligomerization reaction kettle into the reaction rectifying tower;
and a tower kettle of the reaction rectifying tower is provided with a first discharge port, and after a product discharged from the first discharge port is heated by the tower kettle reboiler, one part of the product returns to the deep oligomerization dehydration reaction section again, and the other part of the product is directly collected.
2. The reaction system of claim 1, wherein the tower reboiler is a falling film reboiler, the top of the falling film reboiler is provided with a second inlet, the bottom of the falling film reboiler is provided with a second outlet, the second inlet is communicated with the first outlet, and a part of the substances from the second outlet is introduced into the deep oligomerization and dehydration reaction section, and the other part is directly collected.
3. The reaction system of claim 2, wherein a first transfer pump is disposed on a pipe where the second feed port communicates with the first discharge port.
4. The reaction system of claim 1, wherein a raw material inlet and a reaction product outlet are arranged on the lactic acid oligomerization reaction kettle, the raw material inlet comprises a lactic acid inlet, and the reaction product outlet is arranged at the bottom of the lactic acid oligomerization reaction kettle;
and the reaction product outlet is communicated with the first feed inlet on the reaction rectifying tower.
5. The reaction system of claim 4 wherein a second transfer pump is provided in the conduit communicating the reaction product outlet with the first feed inlet.
6. The reaction system as claimed in claim 5, wherein a circulation pipeline is further disposed on the pipeline connecting the reaction product outlet and the first feeding hole, for returning a part of the substance from the reaction product outlet to the lactic acid oligomerization reaction kettle, and a heat exchanger is disposed on the circulation pipeline.
7. The reaction system of any one of claims 1 to 6, wherein the lactic acid oligomerization reaction kettle is a jacketed stirred reaction kettle.
8. The reaction system according to any one of claims 1 to 6, wherein an overhead condenser is provided at the top of the reactive distillation column for condensing and refluxing water, lactic acid and oligomers distilled from the top of the column.
9. A lactic acid oligomerization reaction method using the reaction system according to any one of claims 1 to 8, characterized by comprising the steps of:
(A) the lactic acid enters the lactic acid oligomerization reaction kettle to react to generate oligomer;
(B) and (4) feeding the oligomer into a reaction rectifying tower for deep dehydration and oligomerization, and rectifying to obtain a final product.
10. The reaction process as claimed in claim 9, wherein the temperature of the rectification reaction in step (B) is controlled to be between 100 ℃ and 200 ℃, preferably between 130 ℃ and 170 ℃, and more preferably 150 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911172939.5A CN112934148A (en) | 2019-11-26 | 2019-11-26 | Reaction system and method for oligomerization of lactic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911172939.5A CN112934148A (en) | 2019-11-26 | 2019-11-26 | Reaction system and method for oligomerization of lactic acid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112934148A true CN112934148A (en) | 2021-06-11 |
Family
ID=76224913
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911172939.5A Pending CN112934148A (en) | 2019-11-26 | 2019-11-26 | Reaction system and method for oligomerization of lactic acid |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112934148A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113461915A (en) * | 2021-07-01 | 2021-10-01 | 江苏科富恺机械设备有限公司 | Lactic acid oligomer synthesis system and method capable of regulating polymerization degree |
| CN114748884A (en) * | 2022-05-07 | 2022-07-15 | 天津大学 | Lactate reaction rectification apparatus for producing |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5142023A (en) * | 1992-01-24 | 1992-08-25 | Cargill, Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
-
2019
- 2019-11-26 CN CN201911172939.5A patent/CN112934148A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5142023A (en) * | 1992-01-24 | 1992-08-25 | Cargill, Incorporated | Continuous process for manufacture of lactide polymers with controlled optical purity |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113461915A (en) * | 2021-07-01 | 2021-10-01 | 江苏科富恺机械设备有限公司 | Lactic acid oligomer synthesis system and method capable of regulating polymerization degree |
| CN113461915B (en) * | 2021-07-01 | 2022-12-06 | 江苏科富恺机械设备有限公司 | Lactic acid oligomer synthesis system and method capable of regulating polymerization degree |
| CN114748884A (en) * | 2022-05-07 | 2022-07-15 | 天津大学 | Lactate reaction rectification apparatus for producing |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN211384958U (en) | Intelligent reaction system for preparing lactide from lactic acid | |
| CN211384959U (en) | Reaction system for preparing lactide from lactic acid | |
| CN211383846U (en) | Reaction system for preparing lactide from oligomer | |
| RU2411990C2 (en) | Method of continuous production of polyethers with high molecular weight by etherification of dicarboxylic acids and/or trans-etherification of dicarboxylic acid ethers by divalent alcohols and/or their mixes, and installation to this end | |
| CN101553309B (en) | Polyester production system employing horizontally elongated esterification vessel | |
| RU2465045C2 (en) | System for production of polyester with reactor of esterification without mixing | |
| US7431893B1 (en) | Process and apparatus for continuous polycondensation | |
| CN112934148A (en) | Reaction system and method for oligomerization of lactic acid | |
| CN211190194U (en) | Reaction system for lactic acid oligomerization | |
| CN111423570A (en) | Process method and device for continuously producing degradable polyester | |
| TWI404565B (en) | Polyester production system employing recirculation of hot alcohol to esterification zone | |
| CN112851628A (en) | Reaction system and method for preparing lactide from lactic acid | |
| CN102020628B (en) | Improved method of preparation process of polylactic acid midbody lactide | |
| CN113234056A (en) | Preparation method and preparation device of crude lactide and prepared crude lactide | |
| RU2474472C2 (en) | Multilevel reactor with internal flute | |
| CA2690721C (en) | Multi-level tubular reactor with vertically spaced segments | |
| CN209752881U (en) | PBT esterification reaction system | |
| US20080139780A1 (en) | Polyester production system employing short residence time esterification | |
| CN112843762A (en) | Reaction system and method for preparing lactide from oligomer | |
| CN112844262A (en) | Intelligent reaction system and method for preparing lactide from lactic acid | |
| CN211486557U (en) | Organic solvent and water continuous removal recovery system in macromolecular compound production | |
| WO2009009036A1 (en) | Multi-level tubular reactor with oppositely extending segments | |
| CN101665564B (en) | Membrane-type dehydration-type lactic acid polycondensation reaction device | |
| JPH11217425A (en) | Method and apparatus for continuous preparation of lactide | |
| CN113842657B (en) | Equipment for circularly preparing lactide |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |