GB2591038A - Synthesis method and device for rapidly producing lactide at high yield - Google Patents
Synthesis method and device for rapidly producing lactide at high yield Download PDFInfo
- Publication number
- GB2591038A GB2591038A GB2102966.5A GB202102966A GB2591038A GB 2591038 A GB2591038 A GB 2591038A GB 202102966 A GB202102966 A GB 202102966A GB 2591038 A GB2591038 A GB 2591038A
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- United Kingdom
- Prior art keywords
- reactor
- lactide
- oligomer
- depolymerization
- purification
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- JJTUDXZGHPGLLC-UHFFFAOYSA-N lactide Chemical compound CC1OC(=O)C(C)OC1=O JJTUDXZGHPGLLC-UHFFFAOYSA-N 0.000 title claims abstract description 140
- 238000001308 synthesis method Methods 0.000 title claims abstract description 9
- 238000000746 purification Methods 0.000 claims abstract description 177
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims abstract description 128
- 238000011084 recovery Methods 0.000 claims abstract description 80
- JVTAAEKCZFNVCJ-REOHCLBHSA-N L-lactic acid Chemical compound C[C@H](O)C(O)=O JVTAAEKCZFNVCJ-REOHCLBHSA-N 0.000 claims abstract description 72
- 229960000448 lactic acid Drugs 0.000 claims abstract description 72
- 239000004310 lactic acid Substances 0.000 claims abstract description 63
- 235000014655 lactic acid Nutrition 0.000 claims abstract description 55
- 239000003054 catalyst Substances 0.000 claims abstract description 46
- 239000002253 acid Substances 0.000 claims abstract description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 28
- 238000002360 preparation method Methods 0.000 claims abstract description 17
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 15
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 15
- 229930182843 D-Lactic acid Natural products 0.000 claims abstract description 9
- JVTAAEKCZFNVCJ-UWTATZPHSA-N D-lactic acid Chemical compound C[C@@H](O)C(O)=O JVTAAEKCZFNVCJ-UWTATZPHSA-N 0.000 claims abstract description 9
- 229940022769 d- lactic acid Drugs 0.000 claims abstract description 9
- 238000006384 oligomerization reaction Methods 0.000 claims description 130
- 238000007599 discharging Methods 0.000 claims description 104
- 239000002994 raw material Substances 0.000 claims description 55
- 238000010992 reflux Methods 0.000 claims description 46
- 238000003860 storage Methods 0.000 claims description 43
- 239000007788 liquid Substances 0.000 claims description 40
- 239000000203 mixture Substances 0.000 claims description 38
- 239000000047 product Substances 0.000 claims description 27
- 238000006243 chemical reaction Methods 0.000 claims description 22
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 16
- 239000011552 falling film Substances 0.000 claims description 13
- 239000006227 byproduct Substances 0.000 claims description 12
- QHGNHLZPVBIIPX-UHFFFAOYSA-N tin(ii) oxide Chemical compound [Sn]=O QHGNHLZPVBIIPX-UHFFFAOYSA-N 0.000 claims description 12
- 238000001704 evaporation Methods 0.000 claims description 11
- 230000008020 evaporation Effects 0.000 claims description 11
- 239000010409 thin film Substances 0.000 claims description 11
- 238000012856 packing Methods 0.000 claims description 10
- KSBAEPSJVUENNK-UHFFFAOYSA-L tin(ii) 2-ethylhexanoate Chemical compound [Sn+2].CCCCC(CC)C([O-])=O.CCCCC(CC)C([O-])=O KSBAEPSJVUENNK-UHFFFAOYSA-L 0.000 claims description 8
- 239000011787 zinc oxide Substances 0.000 claims description 8
- 238000012680 polymerization synthesis reaction Methods 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 6
- 239000007795 chemical reaction product Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 claims description 5
- 239000004246 zinc acetate Substances 0.000 claims description 5
- CANRESZKMUPMAE-UHFFFAOYSA-L Zinc lactate Chemical compound [Zn+2].CC(O)C([O-])=O.CC(O)C([O-])=O CANRESZKMUPMAE-UHFFFAOYSA-L 0.000 claims description 4
- 229940050168 zinc lactate Drugs 0.000 claims description 4
- 239000011576 zinc lactate Substances 0.000 claims description 4
- 235000000193 zinc lactate Nutrition 0.000 claims description 4
- TXUICONDJPYNPY-UHFFFAOYSA-N (1,10,13-trimethyl-3-oxo-4,5,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-17-yl) heptanoate Chemical compound C1CC2CC(=O)C=C(C)C2(C)C2C1C1CCC(OC(=O)CCCCCC)C1(C)CC2 TXUICONDJPYNPY-UHFFFAOYSA-N 0.000 claims description 3
- 229910021626 Tin(II) chloride Inorganic materials 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 239000012264 purified product Substances 0.000 claims description 3
- 235000011150 stannous chloride Nutrition 0.000 claims description 3
- 239000001119 stannous chloride Substances 0.000 claims description 3
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 claims description 3
- ADJMNWKZSCQHPS-UHFFFAOYSA-L zinc;6-methylheptanoate Chemical compound [Zn+2].CC(C)CCCCC([O-])=O.CC(C)CCCCC([O-])=O ADJMNWKZSCQHPS-UHFFFAOYSA-L 0.000 claims description 3
- 241000237519 Bivalvia Species 0.000 claims 1
- 235000020639 clam Nutrition 0.000 claims 1
- 239000000243 solution Substances 0.000 description 19
- JJTUDXZGHPGLLC-IMJSIDKUSA-N 4511-42-6 Chemical compound C[C@@H]1OC(=O)[C@H](C)OC1=O JJTUDXZGHPGLLC-IMJSIDKUSA-N 0.000 description 15
- 239000000463 material Substances 0.000 description 15
- 230000018044 dehydration Effects 0.000 description 13
- 238000006297 dehydration reaction Methods 0.000 description 13
- 238000012691 depolymerization reaction Methods 0.000 description 13
- 239000000539 dimer Substances 0.000 description 13
- 229920000747 poly(lactic acid) Polymers 0.000 description 11
- 239000004626 polylactic acid Substances 0.000 description 11
- 238000000034 method Methods 0.000 description 10
- 239000012535 impurity Substances 0.000 description 6
- 230000008859 change Effects 0.000 description 3
- JJTUDXZGHPGLLC-ZXZARUISSA-N (3r,6s)-3,6-dimethyl-1,4-dioxane-2,5-dione Chemical compound C[C@H]1OC(=O)[C@H](C)OC1=O JJTUDXZGHPGLLC-ZXZARUISSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- -1 D-lactide Chemical compound 0.000 description 2
- AEMRFAOFKBGASW-UHFFFAOYSA-N Glycolic acid Chemical compound OCC(O)=O AEMRFAOFKBGASW-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 239000012974 tin catalyst Substances 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 229920006238 degradable plastic Polymers 0.000 description 1
- 239000007857 degradation product Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 230000004060 metabolic process Effects 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000010137 moulding (plastic) Methods 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000052 poly(p-xylylene) Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007151 ring opening polymerisation reaction Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D319/00—Heterocyclic compounds containing six-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D319/10—1,4-Dioxanes; Hydrogenated 1,4-dioxanes
- C07D319/12—1,4-Dioxanes; Hydrogenated 1,4-dioxanes not condensed with other rings
-
- 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
- B01J19/0006—Controlling or regulating processes
-
- 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
- B01J19/0006—Controlling or regulating processes
- B01J19/0013—Controlling the temperature of the process
-
- 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
- B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
- B01J3/006—Processes utilising sub-atmospheric pressure; Apparatus therefor
-
- 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
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/0015—Feeding of the particles in the reactor; Evacuation of the particles out of the reactor
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
- C08G63/08—Lactones or lactides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
- C08J11/12—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by dry-heat treatment only
-
- 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
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00106—Controlling the temperature by indirect heat exchange
- B01J2208/00115—Controlling the temperature by indirect heat exchange with heat exchange elements inside the bed of solid particles
- B01J2208/00132—Tubes
-
- 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
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00106—Controlling the temperature by indirect heat exchange
- B01J2208/00115—Controlling the temperature by indirect heat exchange with heat exchange elements inside the bed of solid particles
- B01J2208/0015—Plates; Cylinders
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Polyesters Or Polycarbonates (AREA)
- Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)
Abstract
A synthesis method for producing lactide comprising [1] using L-lactic acid, D-lactic acid or DL-lactic acid, and polymerising lactic acid at 100-180oC at pressure of 1-100 KPa to obtain oligolectic acid with a weight-average of 500-3,000 Da; [2] purifying the oligolectic acid to remove unreacted lactic acid and water; and [3] depolymerising the oligolectic acid using a catalyst at 200-260oC at pressure of 0.1-1 KPa, purifying and collecting the lactide. Also disclosed is a synthesis device 1 for producing the lactide, where I refers to oligomer preparation system, II refers to oligomer purification system, III refers to oligomer depolymerisation system, IV refers to lactide purification system and V refers to recovery system.
Description
SYNTHESIS METHOD AND DEVICE FOR RAPIDLY PRODUCING LACTIDE AT
HIGH YIELD
TECHNICAL FIELD
The present invention belongs to the field of synthesizing monomers from environmentally friendly/biomedical degradable materials, particularly relates to an efficient synthesis process of lactide, and specifically relates to a synthesis method and device for rapidly producing lactide at high yield.
BACKGROUND
With the development of times, non-degradable plastic based on petroleum is more and more widely used, which also brings many environmental pollution problems. Meanwhile, the demand for non-renewable petroleum resources of general plastic also affects a sustainable development problem. Polylactic acid is a green polymer material with wide application, which is suitable for extrusion, injection molding, and plastic molding, and after being discarded, the polylactic acid may be degraded into carbon dioxide and water in a natural environment, causing little environmental pollution, thus being one of the best choices to solve the "white pollution". The polylactic acid has a good mechanical strength, a chemical stability, a biocompatibility, and a bioabsorbability. Meanwhile, the polylactic acid is non-toxic and pollution-free, and a degradation product thereof may be used for human metabolism, so that the polylactic acid may be widely used in medical industry, agriculture, food packaging, daily necessities, and other fields.
At present, methods for synthesizing the polylactic acid mainly comprise a one-step method and a two-step method. According to the one-step method, lactic acid, glycolic acid, and derivatives thereof are used as raw materials to directly synthesize the polylactic acid, such as directly polycondensating the lactic acid into the polylactic acid in JP733861, JP599612, and CN198764C, which takes a long time, and has a low molecular weight and a low application value. According to the two-step method, the above raw materials are polycondensated and depolymerized to obtain lactide, and a refined and purified monomer is -t -subjected to ring-opening polymerization to obtain the polylactic acid, such as US5142023, EP261572, JP564688B, and W02009121830. The synthesized polylactic acid has a high relative molecular weight. At present, the two-step method is mainly used for synthesis in industry, and the preparation and purification of the lactide as a synthetic intermediate has become the focus of research. At present, the lactide has a long synthesis time, such as depolymerization for 40 minutes in ZL201510648014.9 and depolymerization for 1 hour to 4 hours in ZL201310146469.1, which may lead to a lovv efficiency and a high running cost after amplification.
SUMMARY
Objective of the invention: a synthesis method for rapidly producing lactide at high yield is provided to solve problems of a long residence time, a low efficiency, and a high cost in commercial lactide synthesis in the prior art, which shortens a residence time of a reactor, improves a yield, and provides a low-cost solution for industrial production of the lactide, In order to achieve the above objective, the technical solutions adopted in the present invention are as follows.
A synthesis method for rapidly producing lactide at high yield comprises the following steps of: (1) using L-lactic acid, D-lactic acid, or DL-lactic acid as a raw material, carrying out a polymerization synthesis reaction at 100°C to 180°C under an absolute pressure of of I KPa to 100 KPa, improving a yield by recovering lactic acid from a light component, and improving a molecular weight of oligolactic acid through reflux a heavy component, so as to obtain oligolactic acid with a weight-average molecular weight of 500 Da to 3,000 Da; (2) purifying the oligolactic acid obtained in step (1) to remove unreacted lactic acid and water; and (3) depolymerizing the oligolactic acid purified in step (2) under an action of a catalyst at 200°C to 260°C under an absolute pressure of 0.1 KPa to 1 KPa, purifying and collecting the light component to obtain a lactide product, and refluxing and depolymerizing the heavy component again.
Further, in step (1), the polymerization synthesis reaction may also be carried out in the presence of an oligomerization catalyst, and the oligomerization catalyst comprises but is not limited to zinc oxide, zinc lactate, zinc acetate, zinc isooctanoate, zinc stearate, stannous oxide, stannous oxide, stannous octoate, stannous chloride, and other zinc or tin catalysts The present invention further provides a synthesis device for rapidly producing lactide at high yield, which comprises: an oligomer preparation system used for carrying out a polymerization synthesis reaction with L-lactic acid, D-lactic acid, or DL-lactic acid as a raw material, so as to obtain oligolactic acid, and introducing a reaction product into an oligomer purification system, the oligomer purification system used for purifying the reaction product introduced from the oligomer preparation system, removing unreacted lactic acid and water, and introducing the purified oligolactic acid into an oligomer depolymerization system; the oligomer depolymerization system used for depolymerizing the purified oligolactic acid under an action of a catalyst, so as to obtain crude lactide, and introducing the crude lactide into a lactide purification system; the lactide purification system used for purifying the crude lactide, so as to obtain a lactide product and a by-product, and introducing the by-product into a recovery system, and the recovery system used for processing and utilizing the by-product.
Specifically, the oligomer preparation system comprises an oligomerization reactor, a raw material pump, an oligomerization catalyst feeding pump, a raw material mixer, an oligomerization discharging/circulating pump, a rectifying tower, and a condenser; wherein, a lactic acid raw material (85% to 90% lactic acid solution) and an oligomerization catalyst respectively enter the raw material mixer through the raw material pump and the oligomerization catalyst feeding pump for mixing at the same time, and then the mixture is fed from a side face of the oligomerization reactor; the oligomerization discharging/circulating pump is located on a discharging pipe at a bottom of the oligomerization reactor, and is connected with a feeding pipe of the oligomer purification system and a side line feeding port of the oligomerization reactor through a three-way valve, and a reflux ratio of an oligomer is controlled to be 20: 1 to 1,000: 1, preferably 30: 1 to 700: 1, and most preferably 50: 1 to 200: 1.
A feeding pipe of the rectifying tower is connected with a top of the oligomerization reactor, a discharging pipe at a top of the rectifying tower is connected with a condensate storage tank after passing through the condenser, and a side face of the condensate storage tank is connected with an oligomerization vacuum system; and a discharging pipe of the condensate storage tank is provided with a condensate circulating/discharging pump, which is connected to a side line feeding pipe of the rectifying tower through a three-way valve. An absolute pressure of the rectifying tower is controlled to be 1 KPa to 100 KPa, preferably 2 KPa to 50 KPa, and most preferably 5 KPa to 20 kPa by the oligomerization vacuum system; and a temperature of the rectifying tower is controlled to be 40°C to 80 °C, preferably 45°C to 75°C, and most preferably 50°C and 70°C.
Specifically, the oligomer purification system comprises an oligomer purification reactor, an oligomer discharging pump, and a purification condenser; a side line feeding port of the oligomer purification reactor is connected with a discharging pipe of the oligomer preparation system; a discharging pipe at a top of the oligomer purification reactor is connected with a purification system condensate storage tank after passing through the purification condenser, and a side face of the purification system condensate storage tank is connected with an oligomer purification vacuum system; a discharging pipe at a bottom of the purification system condensate storage tank is provided with a purification system condensate discharging pump; the oligomer discharging pump is located on a discharging pipe at a bottom of the oligomer purification reactor, and is connected with a feeding pipe of the oligomer depolymerization system; and The oligomer purification reactor is a packed rectifSiing tower; an absolute pressure of a tower top is controlled to be 1 KPa to 50 KPa, preferably 2 KPa to 30 KPa, and most preferably 3 KPa to 20 KPa by the oligomerization purification vacuum system; and a temperature of the tower top is controlled to be 20°C to 70°C, preferably 20°C to 50°C, and most preferably 20°C to 40°C, so as to reduce impurities such as acid, water, and a part of small molecule polymer.
Specifically, the oligomer depolymerization system comprises a depolymerization reactor, a depolymerization catalyst feeding pump, a depolymerization feed mixer, and a depolymerized heavy component discharging/circulating pump.
Wherein, the oligomerization catalyst comprises but is not limited to zinc oxide, zinc lactate, zinc acetate, zinc isooctanoate, zinc stearate, stannous oxide, stannous oxide, stannous octoate, stannous chloride, and other zinc or tin catalysts. The depolymerization catalyst may be the oligomerization catalyst added before, and may be supplemented later. The depolymerization catalyst and a purified product produced by the oligomer purification system enter the depolymerization feed mixer through the depolymerization catalyst feeding pump for mixing at the same time, and then the mixture is fed from a side face of the depolymerization reactor. A reaction temperature of the depolymerization feed mixer is controlled to be 200°C to 260°C, a residence time is 0.5 minute to 5 minutes, and an absolute pressure is 0.1 Kpa to 1 Kpa.
The depolymerized heavy component discharging/circulating pump is located on a discharging pipe at a bottom of the depolymerization reactor, and is connected to the depolymerization feed mixer through a three-way valve, a heavy component produced in the depolymerization reactor is returned to the depolymerization feed mixer to be mixed with a reaction raw material, and then the mixture enters the depolymerization reactor again for reaction; and a light component produced in the depolymerization reactor is connected with a feeding pipe of the lactide purification system through a discharging port above a side face of the depolymerization reactor to remove impurities such as lactic acid and water.
Specifically, the lactide purification system comprises a lactide purification reactor and a lactide storage tank; The lactide storage tank is connected with a discharging port at a bottom of the lactide purification reactor, and a lactide product is conveyed outwards through the lactide discharging pump. Impurities such as lactic acid and water are removed through the lactide purification reactor, so as to obtain a lactide product with a content of L-lactide, D-lactide, or DL-lactide content of 94% to 98%, and a content of meso-lactide is 0.5% to 5.5%.
Uncondensed steam in the lactide purification reactor is connected to a feeding pipe of the recovery system through a by-product discharging port at a top of the lactide purification reactor.
Specifically, the recovery system comprises a recovery system reactor, a recovery liquid storage tank, and a recovery liquid discharging pump; and A side face of the recovery liquid storage tank is connected with a depolymerization vacuum system, and a feeding port at a top of the recovery liquid storage tank is connected with a discharging port at a bottom of the recovery system reactor. Uncondensed steam in the lactide purification reactor is recovered through the recovery system reactor, so as to obtain L-lactic acid, D-lactic acid, or DL-lactic acid solution with a concentration of 65% to 80%. The recovery liquid storage tank discharges a recovery liquid outwards through the recovery liquid discharging pump on a discharging pipe at a bottom of the recovery liquid storage tank.
Specifically, the oligomerization reactor or the depolymerization reactor is any one of a falling-film reactor, a thin film evaporation reactor, a packing reactor, and a double falling-film reactor.
The lactide purification reactor or the recovery system reactor is any one of a shell-and-tube heat exchanger, a plate heat exchanger, a spiral plate heat exchanger, and a tubular heat exchanger.
Beneficial effects: 1. In the present invention, the lactic acid is used as the raw material for reaction, the oligomeric lactic aci d is synthesized by polymerization first, then the oligomeric lactic aci d is purified to remove unreacted lactic acid and water, and depolymerized under the action of the catalyst, so as to obtain the crude lactide, and finally, the crude lactide is purified to obtain the lactide product. The method is capable of effectively shortening a preparation time of the lactide and significantly improving a yield of the lactide.
2. In the present invention, a single component of lactic acid or the lactic acid is added into double components of a catalyst, the mixture passes through a mixer to enter the oligomer preparation system, a residence time is increased through bottom circulation, the oligomeric lactic acid is synthesized, and a gas-phase component passes through the rectification system to improve a yield of the oligomeric lactic acid; the oligomeric lactic acid passes through the purification device to remove unreacted lactic acid and water; and a catalyst is added into the refined oligomeric lactic acid, the mixture passes through a mixer, the mixture enters the depolymerization reactor to be depolymerized into lactide under certain absolute pressure and temperature conditions, the heavy component enters the depolymerization reactor again through reflux, so as to increase a yield of the lactide, and the light component passes through the purification and recovery system to obtain a lactide product. With the adoption of the device, the lactide is capable of being efficiently synthesized, crude lactide with a yield of 94% to 98% is capable of being obtained within a short residence time of 0.5 minute to 5 minutes, a molecular weight of the heavy-component pol yl acti c acid is slowly increased, and the heavy-component polylactic acid is capable of being returned for depolymerization; after the light component passes through the simple purification system, a content of L-lactide, D-lactide or DL-lactide in the lactide product is 94% to 98%, and a content of meso-lacti de is 0.5% to 5.5%, with a simple and rapid operation, a high yield, and easy industrialization.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is further described in detail with reference to the accompanying drawings and the specific embodiments, and the advantages of the above and/or other aspects of the present invention will become clearer.
FIG. 1 is a schematic structure diagram of a synthesis device for rapidly producing lactide at high yield according to the present invention.
Wherein, the reference numerals are respectively represented as follows: I refers to oligomer preparation system; II refers to oligomer purification system; Ill refers to oligomer depolymerization system; IV refers to lactide purification system; V refers to recovery system; 1 refers to lactic acid raw material; 2 refers to raw material pump; 3 refers to oligomerization catalyst; 4 refers to oligomerization catalyst feeding pump; 5 refers to raw material mixer; 6 refers to oligomerization reactor; 7 refers to oligomerization discharging/circulating pump; 8 refers to oligomeric circulating material; 9 refers to oligomer; 10 refers to gas-phase component; 11 refers to rectifying tower; 12 refers to condenser, 13 refers to oligomerization vacuum system; 14 refers to condensate storage tank; 15 refers to condensate circulating/discharging pump; 16 refers to circulating condensate; 17 refers to oligomerization condensate; 18 refers to oligomer purification reactor; 19 refers to oligomer discharging pump; 20 refers to depolymerization catalyst; 21 refers to depolymerization catalyst feeding pump; 22 refers to purified oligomer; 23 refers to oligomer light component; 24 refers to purification condenser, 25 refers to oligomerization purification vacuum system; 26 refers to purification system condensate storage tank; 27 refers to purification system condensate discharging pump, 28 refers to purification system condensate, 29 refers to depolymerization feed mixer, 30 refers to depolymerization reactor, 31 refers to depolymerized heavy component discharging/circulating pump; 32 refers to circulated and depolymerized heavy component; 33 refers to depolymerized heavy component, 34 refers to depolymerized light component; 35 refers to lactide purification reactor; 36 refers to lactide storage tank; 37 refers to lactide discharging pump; 38 refers to lactide product; 39 refers to uncondensed steam; 40 refers to recovery system reactor, 41 refers to depolymerization vacuum system, 42 refers to recovery liquid storage tank; 43 refers to recovery liquid discharging pump; and 44 refers to recovery liquid.
DETAILED DESCRIPTION
The present invention can be better understood according to the following embodiments. The structure, scale, size, etc. shown in the accompanying drawings of the specification are only used to match with the contents disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the executable limiting conditions of the present invention, thus having no technical substantive significance. Any structural modification, change of scale relationship, or adjustment of size shall still fall within the scope covered by the technical contents disclosed in the present invention without affecting the effect and the goal achieved by the present invention. Meanwhile, the terms such as "upper", "lower", "front", "rear", and "middle" cited in the specification are only for convenience of description and clarity, and are not used to limit the implementable scope of the present invention. The change or adjustment of the relative relationship shall be regarded as the implementable scope of the present invention without substantial change of technical content.
In the following embodiments, lactide is prepared by using a device shown in FIG. I. The -8 -device mainly comprises an oligomer preparation system 1, an oligomer purification system II, an oligomer depolymerization system III, a lactide purification system IV, and a recovery system V The oligomer preparation system I is used for carrying out a polymerization synthesis reaction with L-lactic acid, D-lactic acid, or DL-lactic acid as a raw material, so as to obtain oligolactic acid, and a reaction product is introduced into the oligomer purification system II. The oligomer purification system II is used for purifying the reaction product introduced from the oligomer preparation system I to remove unreacted lactic acid and water, and the purified oligolactic acid is introduced into the oligomer depolymerization system III. The oligomer depolymerization system In is used for depolymerizing the purified oligolactic acid under an action of a catalyst, so as to obtain crude lactide, and the obtained crude lactide is introduced into the lactide purification system IV The lactide purification system IV is used for purifying the crude lactide, so as to obtain a lactide product and a by-product, and the byproduct is introduced into the recovery system V The recovery system V is used for processing and utilizing the by-product.
The oligomer preparation system I comprises an oligomerization reactor 6, a raw material pump 2, an oligomerization catalyst feeding pump 4, a raw material mixer 5, an oligomerization discharging/circulating pump 7, a rectifying tower 11, and a condenser 12. A lactic acid raw material 1 and an oligomerization catalyst 3 respectively enter the raw material mixer 5 through the raw material pump 2 and the oligomerization catalyst feeding pump 4 for mixing at the same time, and then the mixture is fed from a side face of the oligomerization reactor 6. The oligomerization discharging/circulating pump 7 is located on a discharging pipe at a bottom of the oligomerization reactor 6, and is connected with a feeding pipe of the oligomer purification reactor 18 and a side line feeding port of the oligomerization reactor 6 through a three-way valve, and a reflux ratio of an oligomer is controlled to be 20: 1 to 1,000: 1. A feeding pipe of the rectifying tower 11 is connected with a top of the oligomerization reactor 6, a discharging pipe at a top of the rectifying tower 11 is connected with a condensate storage tank 14 after passing through a condenser 12, and a side face of the condensate storage tank 14 is connected with an oligomerization vacuum system 13. A discharging pipe of the condensate storage tank 14 is provided with a condensate circulating/discharging pump 15, and is connected to a side line feeding pipe of the rectifying tower 11 through a three-way valve. An absolute pressure of the rectifying tower 11 is controlled to be 1 KPa to 100 KPa by the oligomerization vacuum system 13, and a temperature of the rectifying tower is controlled to be 40°C to 80°C.
The oligomer purification system II comprises an oligomer purification reactor 18, an oligomer discharging pump 19, and a purification condenser 24. A side line feeding port of the oligomer purification reactor 18 is connected with a discharging pipe of the oligomerization reactor 6. A discharging pipe at a top of the oligomer purification reactor 18 is connected with the purification system condensate storage tank 26 after passing through the purification condenser 24, and a side face of the purification system condensate storage tank 26 is connected with the oligomer purification vacuum system 25. A discharging pipe at a bottom of the purification system condensate storage tank 26 is provided with a purification system condensate discharging pump 27. The oligomer discharging pump 19 is located on a discharging pipe at a bottom of the oligomer purification reactor 18, and is connected with a feeding pipe of the depolymerization reactor 30. The oligomer purification reactor 18 is a packed rectifying tower. An absolute pressure of a tower top is controlled to be 1 KPa to 50 KPa by the oligomerization purification vacuum system 25, and a temperature of the tower top is controlled to be 20°C to 70°C, so as to reduce impurities such as acid, water, and a part of small molecular polymer.
The oligomer depolymerization system II comprises a depolymerization reactor 30, a depolymerization catalyst feeding pump 21, a depolymerization feed mixer 29, and a depolymerized heavy component discharge/circulation pump 31. The depolymerization catalyst 20 and a purified product produced by the oligomer purification reactor 18 enter the depolymerization feed mixer 29 through the depolymerization catalyst feeding pump 21 for mixing at the same time, and then the mixture is fed from a side face of the depolymerization reactor 30. A reaction temperature of the depolymerization feed mixer 29 is controlled to be 200°C to 260°C, a residence time is 0.5 minute to 5 minutes, and an absolute pressure is 0.1 Kpa to 1 Kpa. The depolymerized heavy component discharging/circulating pump 31 is located on a discharging pipe at a bottom of the depolymerization reactor 30, and is connected -10 -to the depolymerization feed mixer 29 through a three-way valve, a heavy component produced in the depolymerization reactor 30 is returned to the depolymerization feed mixer 29 to be mixed with a reaction raw material, and then the mixture enters the depolymerization reactor 30 again for reaction. Alight component produced in the depolymerization reactor 30 is connected with a feeding pipe of the lactide purification reactor 35 through a discharging port above a side face of the depolymerization reactor 30 to remove impurities such as lactic acid and water.
The lactide purification system IV comprises a lactide purification reactor 35 and a lactide storage tank 36. The lactide storage tank 36 is connected with a discharging port at a bottom of the lactide purification reactor 35, and the lactide product 38 is conveyed outwards through the lactide discharging pump 37. Impurities such as lactic acid and water are removed through the lactide purification reactor 35, so as to obtain a lactide product with a content of L-lactide, D-lactide, or DL-lactide content of 94% to 98%, and a content of meso-lactide is 0.5% to 5.5%. Uncondensed steam in the lactide purification reactor 35 is connected to a feeding pipe of the recovery system reactor 40 through a by-product discharging port at a top of the lactide purification reactor.
The recovery system V comprises a recovery system reactor 40, a recovery liquid storage tank 42, and a recovery liquid discharging pump 43. A side face of the recovery liquid storage tank 42 is connected with a depolymerization vacuum system 41, and a feeding port at a top of the recovery liquid storage tank is connected with a discharging port at a bottom of the recovery system reactor 40. Uncondensed steam in the lactide purification reactor 35 is recovered through the recovery system reactor 40, so as to obtain L-lactic acid, D-lactic acid, or DL-lactic acid solution with a concentration of 65% to 80%. The recovery liquid storage tank 42 discharges a recovery liquid 44 outwards through the recovery liquid discharging pump 43 on a discharging pipe at a bottom of the recovery liquid storage tank.
Embodiment 1 90% [-lactic acid raw material 1 entered an oligomeri zation reactor 6 at a flow rate of 10 g/h through a raw material pump 2. The oligomerization reactor 6 was a TLNS falling-film -11 -reactor, and the reactor was operated at 80°C under an absolute pressure of 1 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 1,000: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 40°C through reflux. A molecular weight of an oligomer 9 was 500 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a REIL packed rectifying tower with side line feeding, and was operated under an absolute pressure 10 of 1 KPa, and a temperature of a tower top was 20°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst zinc acetate 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor 30 for depolymerization reaction under 0.1 KPa at 220°C. The depolymerization reactor 30 was a WEF thin film evaporation reactor, a residence time was controlled to be 2 minutes, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 2: 1 by a depolymerized heavy component discharging/circulating pump 31. After a refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system.
The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common shell-and-tube heat exchanger of 0.1 m2, and a heat exchange temperature was controlled to be 20°C. After purification, 6.775 Wh lactide product was obtained, with a yield of 94.1%, and a content of L-lactide was 98.1%.
Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a plate heat exchanger of 0.1 m2, and a temperature of the heat exchanger was controlled to be 10°C. A recovery liquid was 0.1 g/h lactic acid solution, a concentration of the L-lactic acid was 70%, and the L-lactic acid was reused after purification.
Embodiment 2 -12 - 90% L-lactic acid raw material 1 was mixed with a catalyst zinc oxide 3 at a flow rate of 20g/h through a raw material pump 2, and then the mixture entered an oligomerization reactor 6. The oligomerization reactor 6 was a TLNS falling-film reactor, and the reactor was operated at 120°C under an absolute pressure of 1 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 300: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the ol igomerizati on reactor 6, and a temperature of a tower top was controlled to be 60°C through reflux. A molecular weight of an oligomer 9 was 1,100 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 20 KPa, and a temperature of a tower top was 25°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 entered a depolymerization reactor 30 for depolymerization reaction under 0.2 KPa at 240°C. The depolymerization reactor 30 was a RFYL packing reactor, a residence time was controlled to be 1.5 minutes, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 2: 1 by a depolymerized heavy component discharging/circulating pump 31. After a refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system.
The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common plate heat exchanger of 0.1 m2, and a heat exchange temperature was controlled to be 60°C. After purification, 14.778 Wh lactide product was obtained, with a weight yield of 94.9%, and a content of L-lactide was 96.9%.
Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a spiral plate heat exchanger of 0.1 m2, and a temperature of the heat exchanger was controlled to be 5°C. A recovery liquid was 0.2 g/h lactic acid solution, a concentration of the [-lactic acid was 65%, and the [-lactic acid was reused after purification. -13-
Embodiment 3 90% [-lactic acid raw material I was mixed with a catalyst zinc acetate 3 at a flow rate of 50 g/h through a raw material pump 2, and then the mixture entered an oligomerization reactor 6. The oligomerization reactor 6 was a WEF thin film evaporation reactor, and the reactor was operated at 180°C under an absolute pressure of 100 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 20: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction.
Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 70°C through reflux. A molecular of an oligomer 9 was 800 Da The oligomer 9 entered an oligomer purification reactor 18, the reactor was a REJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 40 KPa, and a temperature of a tower top was 40°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 entered a depolymerization reactor 30 for depolymerization reaction under 1 KPa at 260°C. The depolymerization reactor 30 was a TLNS falling-film reactor, a residence time was controlled to be I minute, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0.5: 1 by a depolymerized heavy component discharging/circulating pump 31. After a refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system.
The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common spiral plate heat exchanger of 0.2 m2, and a heat exchange temperature was controlled to be 20°C. After purification, 36.639 g/h lactide product was obtained, with a weight yield of 94.1%, and a content of L-lactide was 95.1%. Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a tubular heat exchanger of 0.2 m2, and a temperature of the heat -14 -exchanger was controlled to be 25°C. A recovery liquid was 0.4 g/h lactic acid solution, a concentration of the L-lactic acid was 80%, and the L-lactic acid was reused after purification.
Embodiment 4 90% L-lactic acid raw material 1 entered an oligomerization reactor 6 at a flow rate of 50 g/h through a raw material pump 2. The oligomerization reactor 6 was a WEF thin film evaporation reactor, and the reactor was operated at 170°C under an absolute pressure of 50 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 50: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 80°C through reflux. A molecular of an oligomer 9 was 1,200 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 50 KPa, and a temperature of a tower top was 70°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst stannous octoate 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor 30 for depolymerization reaction under 0.1 KPa at 230°C. The depolymerization reactor 30 was a WEF thin film evaporation reactor, a residence time was controlled to be 0.5 minute, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 1: 1 by a depolymerized heavy component discharging/circulating pump 31. After a refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system.
The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common tubular heat exchanger of 0.2 m2, and a heat exchange temperature was controlled to be 50°C. After purification, 36.879 g/h lacti de product was obtained, with a weight yield of 94.1%, and a content of L-lactide was 97.8%.
-15 -Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a shell-and-tube heat exchanger of 0.2 m2, and a temperature of the heat exchanger was controlled to be 20°C. A recovery liquid was 0.45 g/h lactic acid solution, a concentration of the L-lactic acid was 75%, and the L-lactic acid was reused after purification.
Embodiment 5 90% L-lactic acid raw material 1 entered an oligomerization reactor 6 at a flow rate of 50 gill through a raw material pump 2. The oligomerization reactor 6 was a WEF thin film evaporation reactor, and the reactor was operated at 160°C under an absolute pressure of 20 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 100: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 60°C through reflux. A molecular of an oligomer 9 was 1,500 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 20 KPa, and a temperature of a tower top was 40°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst stannous octoate 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor 30 for depolymerization reaction under 0.1 KPa at 250°C. The depolymerization reactor 30 was a RFJL packing reactor, a residence time was controlled to be 0.7 minute, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0.1: 1 by a depolymerized heavy component discharging/circulating pump 31. After a refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system. The depolymerized light component 34 entered alactide purification reactor 35 after heat tracing transportation, the reactor was a common shell-and-tube heat exchanger of 0.2 m2, and -16 -a heat exchange temperature was controlled to be 60°C. After purification, 37.121 g/h lactide product was obtained, with a weight yield of 95.4%, and a content of L-lactide was 96.2%. Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a plate heat exchanger of 0.2 m2, and a temperature of the heat exchanger was controlled to be 40°C. A recovery liquid was 0.3 g/h lactic acid solution, a concentration of the L-lactic acid was 85%, and the L-lactic acid was reused after purification.
Embodiment 6 90% L-lactic acid raw material 1 was mixed with a catalyst stannous octoate 3 at a flow rate of 50 g/h through a raw material pump 2, and then the mixture entered an oligomerization reactor 6. The oligomerization reactor 6 was a WEF thin film evaporation reactor, and the reactor was operated at 160°C under an absolute pressure of 20 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 100: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction.
Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 60°C through reflux. A molecular of an oligomer 9 was 1,500 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 20 K Pa, and a temperature of a tower top was 40°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 entered a depolymerization reactor 30 for depolymerization reaction under 0.2 KPa at 260°C. The depolymerization reactor 30 was a TLNS double-falling-film reactor, a residence time was controlled to be 0.5 minute, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0: 1 by a depolymerized heavy component discharging/circulating pump 31. After the refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again and a depolymerized light component 34 entered a subsequent purification system.
-17 -The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common plate heat exchanger of 0.2 m2, and a heat exchange temperature was controlled to be 50°C. After purification, 37.297 g/h lactide product was obtained, with a weight yield of 95.9%, and a content of L-lactide was 95.2%.
Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a spiral plate heat exchanger of 0.2 m2, and a temperature of the heat exchanger was controlled to be -20°C. A recovery liquid was 0.32 g/h lactic acid solution, a concentration of the L-lactic acid was 50 and the [-lactic acid was reused after purification.
Embodiment 7 90% [-lactic acid raw material 1 entered an oligomerization reactor 6 at a flow rate of 30 g/h through a raw material pump 2. The oligomerization reactor 6 was a RFJL packing reactor, and the reactor was operated at 170°C under an absolute pressure of 50 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 80: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 60°C through reflux. A molecular of an oligomer 9 was 1,600 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFIL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 15 KPa, and a temperature of a tower top was 35°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst zinc lactate 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor for depolymerization reaction under 0.1 KPa at 260°C. The depolymerization reactor 30 was a TLNS falling-film reactor, a residence time was controlled to be 1.0 minute, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0: 1 by a depolymerized heavy component discharging/circulating pump 31. After the refluxed heavy component was -18 -mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system.
The depolymerized light component 34 entered alactide purification reactor 35 after heat tracing transportation, the reactor was a common spiral plate heat exchanger of 0.2 m2, and a heat exchange temperature was controlled to be 60°C. After purification, 22.877 g/h lactide product was obtained, with a weight yield of 98.0%, and a content of L-lactide was 96.4%. Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a tubular heat exchanger of 0.2 n-12, and a temperature of the heat exchanger was controlled to be 10°C. A recovery liquid was 0.11 g/h lactic acid solution, a concentration of the L-lactic acid was 75%, and the L-lactic acid was reused after purification.
Embodiment 8 90% L-lactic acid raw material 1 entered an oligomerization reactor 6 at a flow rate of 30 g/h through a raw material pump 2. The oligomerization reactor 6 was a RFJL packing reactor, and the reactor was operated at 160°C under an absolute pressure of 50 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 200: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 60°C through reflux. A molecular of an oligomer 9 was 3,000 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a REJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 15 KPa, and a temperature of a tower top was 35°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst stannous octoate 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor 30 for depolymerization reaction under 0.1 KPa at 250°C. The depolymerization reactor 30 was a WEF thin film evaporation reactor, a residence time was controlled to be 1.5 -19 -minutes, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 1: 1 by a depolymerized heavy component discharging/circulating pump 31. After the refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system.
The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common tubular heat exchanger of 0.15 m2, and a heat exchange temperature was controlled to be 60°C. After purification, 22.195 g/h lactide product was obtained, with a weight yield of 95.2%, and a content of L-lactide was 96.8%.
Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a shell-and-tube heat exchanger of 0.15 m2, and a temperature of the heat exchanger was controlled to be 10°C. A recovery liquid was 0.2 g/h lactic acid solution, a concentration of the L-lactic acid was 80%, and the L-lactic acid was reused after purification.
Embodiment 9 90% L-lactic acid raw material 1 entered an oligomerization reactor 6 at a flow rate of 60 g/h through a raw material pump 2. The oligomerization reactor 6 was a RFJL packing reactor, and the reactor was operated at 170°C under an absolute pressure of 50 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 100: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 60°C through reflux. A molecular of an oligomer 9 was 1,500 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 20 KPa, and a temperature of a tower top was 30°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerizati on catalyst zinc oxide 20 were mixed evenly -20 -by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor 30 for depolymerization reaction under 0.1 KPa at 260°C. The depolymerization reactor 30 was a TLNS falling-film reactor, a residence time was controlled to be 1.0 minute, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0.2: 1 by a depolymerized heavy component discharging/circulating pump 31. After the refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system The depolymerized light component 34 entered alacti de purification reactor 35 after heat tracing transportation, the reactor was a common shell-and-tube heat exchanger of 0.25 m2, and a heat exchange temperature was controlled to be 60°C. After purification, 42.851 g/h lactide product was obtained, with a weight yield of 97.2%, and a content of L-lactide was 95.1%.
Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a plate heat exchanger of 0.25 m2, and a temperature of the heat exchanger was controlled to be 10°C. A recovery liquid was 0.4 g/h lactic acid solution, a concentration of the L-lactic acid was 78%, and the L-I acti c acid was reused after purification.
Embodiment 10 85% [-lactic acid raw material 1 entered an oligomerization reactor 6 at a flow rate of 50 g/h through a raw material pump 2. The oligomerization reactor 6 was a RFJL packing reactor, and the reactor was operated at 160°C under an absolute pressure of 50 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 150: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction.
Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 60°C through reflux. A molecular of an oligomer 9 was 2,500 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFJL packed rectifying tower with side line feeding, and was operated under an absolute pressure -21 -of 15 KPa, and a temperature of a tower top was 35°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst zinc oxide 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor 30 for depolymerization reaction under 0.2 KPa at 250°C. The depolymerization reactor 30 was a double-falling-film reactor, a residence time was controlled to be 1.0 minute, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0: 1 by a depolymerized heavy component discharging/circulating pump 3L After the refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system.
The depolymerized light component 34 entered alacti de purification reactor 35 after heat tracing transportation, the reactor was a common plate heat exchanger of 0.2 m2, and a heat exchange temperature was controlled to be 60°C. After purification, 36.644 g/h lactide product was obtained, with a weight yield of 94.3%, and a content of [-lactide was 96.7%.
Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a spiral plate exchanger of 0.2 m2, and a temperature of the heat exchanger was controlled to be 10°C. A recovery liquid was 0.24 g/h lactic acid solution, a concentration of the L-lactic acid was 75%, and the L-lactic acid was reused after purification.
Embodiment 11 90% [-lactic acid raw material I entered an oligomerization reactor 6 at a flow rate of 50 g/h through a raw material pump 2. The oligomerization reactor 6 was a double-falling-film reactor, and the reactor was operated at 160°C under an absolute pressure of 50 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 120: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 60°C through reflux. A molecular of an oligomer 9 was 2,000 Da.
-22 -The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFIL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 15 KPa, and a temperature of a tower top was 35°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst zinc oxide 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor 30 for depolymerization reaction under 0.2 KPa at 250°C. The depolymerization reactor 30 was a WEE thin film evaporation reactor, a residence time was controlled to be LO minute, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0: 1 by a depolymerized heavy component discharging/circulating pump 31. After the refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system. The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common spiral plate heat exchanger of 0.2 m2, and a heat exchange temperature was controlled to be 60°C. After purification, 36.828 g/h lactide product was obtained, with a weight yield of 94.7%, and a content of L-lactide was 97.3%. Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a tubular heat exchanger of 0.2 m2, and a temperature of the heat exchanger was controlled to be 5°C. A recovery liquid was 0.3 g/h lactic acid solution, a concentration of the L-lactic acid was 75%, and the L-lactic acid was reused after purification.
Embodiment 12 90% D-lactic acid raw material I entered an oligomerization reactor 6 at a flow rate of 50 g/h through a raw material pump 2. The oligomerization reactor 6 was a double-falling-film reactor, and the reactor was operated at 160°C under an absolute pressure of 20 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 100: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the -23 -oligomerization reactor 6, and a temperature of a tower top was controlled to be 50°C through reflux. A molecular of an oligomer 9 was 1,400 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 15 KPa, and a temperature of a tower top was 30°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst stannous octoate 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor 30 for depolymerization reaction under 0.2 KPa at 250°C. The depolymerization reactor 30 was a RFJL packing reactor, a residence time was controlled to be 1.5 minutes, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0: 1 by a depolymerized heavy component discharging/circulating pump 31. After the refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor 30 again, and a depolymerized light component 34 entered a subsequent purification system.
The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common tubular heat exchanger of 0.2 m2, and a heat exchange temperature was controlled to be 60°C. After purification, 36.759 g/h lactide product was obtained, with a weight yield of 94.5%, and a content of L-lactide was 96.1%.
Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a tubular heat exchanger of 0.2 m2, and a temperature of the heat exchanger was controlled to be 8°C. A recovery liquid was 0.5 g/h lactic acid solution, a concentration of the L-lactic acid was 70%, and the L-lactic acid was reused after purification.
Embodiment 13 90% DL-lactic acid raw material 1 entered an oligomerization reactor 6 at a flow rate of g/h through a raw material pump 2. The oligomerization reactor 6 was a RFJL packing reactor, and the reactor was operated at 170'0 under an absolute pressure of 20 KPa for dehydration and oligomerization. A reflux ratio of a dehydrated oligomer was controlled to be 80: 1 by an oligomerization discharging/circulation pump 7, and then the dehydrated oligomer -24 -was refluxed to a side line feeding port of the oligomerization reactor 6 for continuous reaction. Lactic acid was refluxed through a rectifying tower 11 at a top of the oligomerization reactor 6, and a temperature of a tower top was controlled to be 50C through reflux. A molecular of an oligomer 9 was 1,600 Da.
The oligomer 9 entered an oligomer purification reactor 18, the reactor was a RFJL packed rectifying tower with side line feeding, and was operated under an absolute pressure of 10 KPa, and a temperature of a tower top was 25°C. Removed acid, water, and dimer were purified and reused.
A purified oligomer 22 and a depolymerization catalyst zinc oxide 20 were mixed evenly by a depolymerization feed mixer 29, and then the mixture entered a depolymerization reactor for depolymerization reaction under 0.1 KPa at 250'C. The depolymerization reactor 30 was a WEF thin film evaporation reactor, a residence time was controlled to be 1.5 minutes, and a reflux ratio of a depolymerized heavy component 33 was controlled to be 0: 1 by a depolymerized heavy component discharging/circulating pump 3L After the refluxed heavy component was mixed with a new material, the mixture entered the depolymerization reactor again, and a depolymerized light component 34 entered a subsequent purification system. The depolymerized light component 34 entered a lactide purification reactor 35 after heat tracing transportation, the reactor was a common tubular heat exchanger of 0.2 m2, and a heat exchange temperature was controlled to be 60°C. After purification, 36.81 gill lactide product 20 was obtained, with a weight yield of 94.6%, and a content of L-lactide was 97.7%.
Uncondensed steam 39 in a lactide purification reactor 35 entered a recovery system reactor 40, the reactor was a shell-and-tube heat exchanger of 0.2 m2, and a temperature of the heat exchanger was controlled to be 8C. A recovery liquid was 0.54 g/h lactic acid solution, a concentration of the L-lactic acid was 72%, and the L-lactic acid was reused after purification.
The present invention provides an idea and a method for a synthesis method and device for rapidly producing lactide at high yield, with many methods and ways to realize the technical solution specifically. Those described above are merely the preferred embodiments of the present invention, and it shall be pointed out that those of ordinary skills in the art may -25 -further make improvements and decorations without departing from the principle of the present invention, and these improvements and decorations shall also be regarded as the scope of protection of the present invention. All unspecified components in the embodiments can be implemented in the prior art -26 -
Claims (10)
- CLAMS: 1. A synthesis method for rapidly producing lactide at high yield, comprising the following steps of: (1) using L-lactic acid, D-lactic acid, or DL-lactic acid as a raw material, carrying out a polymerization synthesis reaction at 100°C to 180°C under an absolute pressure of 1 KPa to KPa, improving a yield by recovering lactic acid from a light component, and improving a molecular weight of oligolactic acid through reflux a heavy component, so as to obtain oligolactic acid with a weight-average molecular weight of 500 Da to 3,000 Da; (2) purifying the oligolactic acid obtained in step (1) to remove unreacted lactic acid and water; and (3) depolymerizing the oligolactic acid purified in step (2) under an action of a catalyst at 200°C to 260°C under an absolute pressure of 0.1 KPa to 1 KPa, purifying and collecting the light component to obtain a lactide product, and refluxing and depolymerizing the heavy component again.
- 2. The synthesis method for rapidly producing lactide at high yield according to claim 1, wherein in step (1), the polymerization synthesis reaction is carried out in the presence of an oligomerization catalyst, and the oligomerization catalyst is any one of zinc oxide, zinc lactate, zinc acetate, zinc isooctanoate, zinc stearate, stannous oxide, stannous oxide, stannous octoate, or stannous chloride.
- 3. A synthesis device for rapidly producing lactide at high yield, comprising: an oligomer preparation system (I) used for carrying out a polymerization synthesis reaction with L-lactic acid, D-lactic acid, or DL-lactic acid as a raw material, so as to obtain oligolactic acid, and introducing a reaction product into an oligomer purification system (II); the oligomer purification system (II) used for purifying the reaction product introduced from the oligomer preparation system (I), removing unreacted lactic acid and water, and introducing the purified oligolactic acid into an oligomer depolymerization system (III); the oligomer depolymerization system (III) used for depolymerizing the purified oligolactic acid under an action of a catalyst, so as to obtain crude lactide, and introducing the crude lactide into a lactide purification system (IV); -27 -the lactide purification system (IV) used for purifying the crude lactide, so as to obtain a lactide product and a by-product, and introducing the by-product into a recovery system (V); and the recovery system (V) used for processing and utilizing the by-product
- 4. The synthesis device for rapidly producing lactide at high yield according to claim 3, wherein the oligomer preparation system (I) comprises an oligomerization reactor (6), a raw material pump (2), an oligomerization catalyst feeding pump (4), a raw material mixer (5), an oligomerization discharging/circulating pump (7), a rectifying tower (11), and a condenser (12), wherein, a lactic acid raw material (1) and an oligomerization catalyst (3) respectively enter the raw material mixer (5) through the raw material pump (2) and the oligomerization catalyst feeding pump (4) for mixing at the same time, and then the mixture is fed from a side face of the oligomerization reactor (6), the oligomerization discharging/circulating pump (7) is located on a discharging pipe at a bottom of the oligomerization reactor (6), and is connected with a feeding pipe of the oligomer purification system (II) and a side line feeding port of the oligomerization reactor (6) through a three-way valve; a feeding pipe of the rectifying tower (11) is connected with a top of the oligomerization reactor (6), a discharging pipe at a top of the rectifying tower (11) is connected with a condensate storage tank (14) after passing through the condenser (12), and a side face of the condensate storage tank (14) is connected with an oligomerization vacuum system (13); and a discharging pipe of the condensate storage tank (14) is provided with a condensate circulating/discharging pump (15), which is connected to a side line feeding pipe of the rectifying tower (11) through a three-way valve
- 5. The synthesis device for rapidly producing lactide at high yield according to claim 3, wherein the oligomer purification system (II) comprises an oligomer purification reactor (18), an oligomer discharging pump (19), and a purification condenser (24); a side line feeding port of the oligomer purification reactor (18) is connected with a discharging pipe of the oligomer preparation system (I); a discharging pipe at a top of the -28 -oligomer purification reactor (18) is connected with a purification system condensate storage tank (26) after passing through the purification condenser (24), and a side face of the purification system condensate storage tank (26) is connected with an oligomer purification vacuum system (25), a discharging pipe at a bottom of the purification system condensate storage tank (26) is provided with a purification system condensate discharging pump (27), the oligomer discharging pump (19) is located on a discharging pipe at a bottom of the oligomer purification reactor (18), and is connected with a feeding pipe of the oligomer depolymerizati on system (III) and the oligomer purification reactor (18) is a packed rectifying tower.
- 6. The synthesis device for rapidly producing lactide at high yield according to claim 3, wherein the oligomer depolymerization system (III) comprises a depolymerization reactor (30), a depolymerization catalyst feeding pump (21), a depolymerization feed mixer (29), and a depolymerized heavy component discharging/circulating pump (31), wherein, the depolymerization catalyst (20) and the purified product produced by the oligomer purification system (II) enter the depolymerization feed mixer (29) through the depolymerization catalyst feeding pump (21) for mixing at the same time, and then the mixture is fed from a side face of the depolymerization reactor (30); the depolymerized heavy component discharging/circulating pump (31) is located on a discharging pipe at a bottom of the depolymerization reactor (30), and is connected to the depolymerization feed mixer (29) through a three-way valve, a heavy component produced in the depolymerization reactor (30) is returned to the depolymerization feed mixer (29) to be mixed with a reaction raw material, and then the mixture enters the depolymerization reactor (30) again for reaction; and a light component produced in the depolymerization reactor (30) is connected with a feeding pipe of the lactide purification system (IV) through a discharging port above a side face of the depolymerization reactor (30).
- 7. The synthesis device for rapidly producing lactide at high yield according to claim 3, wherein the lactide purification system (IV) comprises a lactide purification reactor (35) and a lactide storage tank (36); the lactide storage tank (36) is connected with a discharging port at a bottom of the lactide -29 -purification reactor (35), and a lactide product (38) is conveyed outwards through a lactide discharging pump (37); and a by-product discharging port at a top of the lactide purification reactor (35) is connected to a feeding pipe of the recovery system (V).
- 8. The synthesis device for rapidly producing lactide at high yield according to claim 3, wherein the recovery system (V) comprises a recovery system reactor (40), a recovery liquid storage tank (42), and a recovery liquid discharging pump (43); and a side face of the recovery liquid storage tank (42) is connected with a depolymerization vacuum system (41), and a feeding port at a top of the recovery liquid storage tank is connected with a discharging port at a bottom of the recovery system reactor (40); and the recovery liquid storage tank (42) discharges a recovery liquid (44) outwards through the recovery liquid discharging pump (43) on a discharging pipe at a bottom of the recovery liquid storage tank.
- 9. The synthesis device for rapidly producing lactide at high yield according to claim 4 or 6, wherein the oligomerization reactor (6) or the depolymerization reactor (30) is any one of a falling-film reactor, a thin film evaporation reactor, a packing reactor, and a double falling-film reactor.
- 10. The synthesis device for rapidly producing lactide at high yield according to claim 7 or 8, wherein the lactide purification reactor (35) or the recovery system reactor (40) is any one of a shell-and-tube heat exchanger, a plate heat exchanger, a spiral plate heat exchanger, and a tubular heat exchanger.-30 -
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| CN112480063A (en) * | 2020-11-28 | 2021-03-12 | 万华化学(四川)有限公司 | Reaction process for preparing low-acid-content lactide |
| CN112480064A (en) * | 2020-12-21 | 2021-03-12 | 天津科技大学 | Method for synthesizing lactide through back-pack type continuous rectification |
| CN112679464B (en) * | 2021-01-18 | 2023-05-30 | 万华化学(四川)有限公司 | Method for preparing lactide in high yield |
| WO2022155762A1 (en) * | 2021-01-19 | 2022-07-28 | 万华化学(四川)有限公司 | Preparation method for lactide and reaction device |
| CN112876453A (en) * | 2021-01-29 | 2021-06-01 | 南京华基塔业有限公司 | Reaction system and method for preparing lactide from lactic acid |
| CN112933630A (en) * | 2021-01-29 | 2021-06-11 | 南京华基塔业有限公司 | Intelligent micro-interface reaction system and method for preparing lactide from lactic acid |
| CN114160064B (en) * | 2021-01-29 | 2024-01-26 | 安徽丰原生物技术股份有限公司 | Device and method for industrially preparing L-lactide |
| CN113651794B (en) * | 2021-09-15 | 2022-08-02 | 珠海格力新材料有限公司 | Lactide synthesis method |
| CN116063271B (en) * | 2021-10-31 | 2024-05-31 | 中国石油化工股份有限公司 | Method for preparing lactide from high molecular weight lactic acid oligomer |
| CN116063270A (en) | 2021-10-31 | 2023-05-05 | 中国石油化工股份有限公司 | Method and system for continuously preparing lactide through step control |
| CN114471438B (en) * | 2022-02-18 | 2023-08-25 | 华陆工程科技有限责任公司 | Reaction device and method for industrially preparing lactide |
| CN115677649B (en) * | 2022-11-16 | 2024-02-13 | 寿光金远东变性淀粉有限公司 | Method for efficiently preparing and purifying lactide |
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