技术领域Technical field
本发明属于无金属绿色催化、生物可降解塑料化学回收领域；尤其涉及一种醋酸双环胍盐催化废弃聚乳酸醇解的方法。The invention belongs to the field of metal-free green catalysis and chemical recycling of biodegradable plastics; in particular, it relates to a method for the alcoholysis of waste polylactic acid catalyzed by bicyclic guanidine acetate.
背景技术Background technique
聚乳酸(PLA)由于具有良好的生物可降解性、易加工性和生物可相容性，在一次性包装材料、药物缓释、血管支架等领域被广泛应用。近些年来，聚乳酸的废弃量急剧上升，寻找合适的方法回收废弃PLA已经成为现阶段的研究热点。通过化学方法将废弃PLA降解成高附加值化学品是目前废弃PLA资源化利用的有效途径。PLA的化学回收主要包括水解法、光解法、热解法以及醇解法等。其中，醇解法具有反应条件温和，利于工业化操作等优点，并且可将废弃聚乳酸降解为对应的乳酸酯，以增加回收废弃聚乳酸的经济效益。乳酸酯是一类重要的化学品，在涂料、香料合成、树脂、黏结剂、精密电子元件清洗剂的生产以及精细化工品加工等行业被广泛应用。Polylactic acid (PLA) is widely used in disposable packaging materials, drug sustained release, vascular stents and other fields due to its good biodegradability, easy processability and biocompatibility. In recent years, the amount of discarded polylactic acid has increased sharply, and finding suitable methods to recycle discarded PLA has become a research hotspot at this stage. Degrading waste PLA into high value-added chemicals through chemical methods is currently an effective way to utilize waste PLA resources. The chemical recycling of PLA mainly includes hydrolysis, photolysis, pyrolysis and alcoholysis. Among them, the alcoholysis method has the advantages of mild reaction conditions and is conducive to industrial operations, and can degrade waste polylactic acid into the corresponding lactic acid ester to increase the economic benefits of recycling waste polylactic acid. Lactic acid ester is an important class of chemicals that is widely used in industries such as coatings, perfume synthesis, resins, adhesives, precision electronic component cleaning agents, and fine chemical processing.
目前，PLA醇解工艺常用催化剂为金属催化剂及其络合物、离子液体等含金属的化合物，在使用过程中存在金属残留的问题，增加了产物乳酸酯的提纯难度，并且限制了乳酸酯在一些精细化工品行业中的应用。无金属催化剂以其环保、低毒等优点，在催化PLA醇解的应用中得到了越来越多的关注，但也存在着催化剂活性低、稳定性差等问题。At present, the commonly used catalysts in the PLA alcoholysis process are metal catalysts and their complexes, ionic liquids and other metal-containing compounds. There are problems with metal residues during use, which increases the difficulty of purifying the product lactic acid ester and limits the lactic acid ester. The application of esters in some fine chemical industries. Metal-free catalysts have received more and more attention in the application of catalyzing the alcoholysis of PLA due to their environmental protection and low toxicity. However, there are also problems such as low catalyst activity and poor stability.
发明内容Contents of the invention
发明目的：针对现有技术中废弃聚乳酸醇解过程存在的反应速率低、乳酸酯产率低、产物中金属残留等问题，设计开发了醋酸双环胍盐催化废弃聚乳酸醇解的方法，以提高反应速率和改善反应条件。Purpose of the invention: In view of the problems existing in the existing technology in the alcoholysis process of waste polylactic acid, such as low reaction rate, low lactate ester yield, and metal residues in the product, a method for the alcoholysis of waste polylactic acid catalyzed by bicyclic guanidine acetate was designed and developed. To increase the reaction rate and improve reaction conditions.
为达成上述目的，提供的具体技术方案如下：To achieve the above goals, the specific technical solutions provided are as follows:
一种醋酸双环胍盐催化聚乳酸醇解的方法，涉及醋酸双环胍盐在醇解废弃聚乳酸中的应用。A method for the alcoholysis of polylactic acid catalyzed by bicyclic guanidine acetate, involving the application of bicyclic guanidine acetate in the alcoholysis of waste polylactic acid.
具体地，以醇为溶剂，将醋酸双环胍盐催化剂与废弃聚乳酸进行降解反应，得到对应的乳酸酯。Specifically, using alcohol as a solvent, the bicyclic guanidine acetate catalyst and waste polylactic acid are degraded to obtain the corresponding lactic acid ester.
反应方程式如下：The reaction equation is as follows:
其中，所述的醇为甲醇、乙醇、丙醇、丁醇、异戊醇、异辛醇、正十二醇或苯甲醇中的任意一种。Wherein, the alcohol is any one of methanol, ethanol, propanol, butanol, isoamyl alcohol, isooctyl alcohol, n-dodecanol or benzyl alcohol.
其中，所述聚乳酸包括但不限于废弃聚乳酸，所述废弃聚乳酸为废弃聚乳酸包装袋、废弃聚乳酸吸管和废弃聚乳酸3D打印材料中的任意一种或者几种的组合。Wherein, the polylactic acid includes but is not limited to waste polylactic acid, which is any one or a combination of waste polylactic acid packaging bags, waste polylactic acid straws and waste polylactic acid 3D printing materials.
其中，所述的醋酸双环胍盐由1,5,7-三叠氮双环(4.4.0)癸-5-烯(有机碱TBD)与醋酸按照摩尔比为1:1反应得到。Wherein, the bicyclic guanidine acetate salt is obtained by reacting 1,5,7-triazidobicyclo(4.4.0)dec-5-ene (organic base TBD) and acetic acid at a molar ratio of 1:1.
其中，所述醋酸双环胍盐催化剂质量与PLA质量比为1:40～1:10，优选为1:20～3:40。Wherein, the mass ratio of the bicyclic guanidine acetate catalyst to the mass of PLA is 1:40 to 1:10, preferably 1:20 to 3:40.
其中，所述醇的质量与废弃聚乳酸质量比为5:1～12.5:1，优选为7.5:1～10:1。Wherein, the mass ratio of the alcohol to the waste polylactic acid is 5:1 to 12.5:1, preferably 7.5:1 to 10:1.
其中，所述降解反应的条件为常压，反应温度为140℃～200℃，优选为160℃～200℃。Wherein, the conditions of the degradation reaction are normal pressure, and the reaction temperature is 140°C to 200°C, preferably 160°C to 200°C.
其中，所述降解反应时间为0.5h～3h，优选为2h～3h。Wherein, the degradation reaction time is 0.5h-3h, preferably 2h-3h.
其中，所述的降解反应结束后，进行催化剂回收处理。所述的催化剂回收处理，将降解反应液减压抽滤、萃取，滤液经水萃取，萃取液为含有醋酸双环胍盐的溶液，蒸发去除水分，回收得到醋酸双环胍盐或醋酸双环胍盐的醇溶液；萃余液为含有乳酸酯的醇溶液。Wherein, after the degradation reaction is completed, the catalyst is recovered. In the described catalyst recovery process, the degradation reaction liquid is filtered and extracted under reduced pressure. The filtrate is extracted with water. The extract is a solution containing bicyclic guanidine acetate salt. The water is evaporated to remove the water, and the bicyclic guanidine acetate salt or bicyclic guanidine acetate salt is recovered. Alcohol solution; the raffinate is an alcohol solution containing lactic acid ester.
所述的回收得到醋酸双环胍盐或醋酸双环胍盐的醇溶液作为催化剂循环使用，具有优越的循环使用性能，重复使用5次后，催化活性没有明显降低。The bicyclic guanidine acetate or the alcohol solution of the bicyclic guanidine acetate salt obtained through the recovery is recycled as a catalyst and has excellent recycling performance. After repeated use 5 times, the catalytic activity does not decrease significantly.
其中，PLA的转化率和乳酸酯的产率分别按公式(1)(2)计算Among them, the conversion rate of PLA and the yield of lactic acid ester are calculated according to formulas (1) (2) respectively.
有益效果：Beneficial effects:
本发明以醋酸双环胍盐为催化剂，醇解废弃聚乳酸生成乳酸酯。所用催化剂催化活性高、热稳定性高，在一定条件下可得较高产率的乳酸酯；醋酸双环胍盐不含金属、稳定性高，可以有效解决产物中的金属残留问题，且催化剂可循环使用，为废弃PLA的醇解回收利用提供了一种新工艺方法，具有优异的工业化应用前景。The invention uses bicyclic guanidine acetate as a catalyst to alcoholyze waste polylactic acid to generate lactic acid ester. The catalyst used has high catalytic activity and high thermal stability, and can obtain lactate ester with a higher yield under certain conditions; the bicyclic guanidine acetate salt does not contain metal and has high stability, which can effectively solve the problem of metal residues in the product, and the catalyst can Recycling provides a new process method for the alcoholysis recycling of waste PLA and has excellent industrial application prospects.
附图说明Description of the drawings
下面结合附图和具体实施方式对本发明做更进一步的具体说明，本发明的上述和/或其他方面的优点将会变得更加清楚。The above and/or other advantages of the present invention will become more clear when the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.
图1为本发明中的催化剂醋酸双环胍盐(HTBD-OAc)和TBD的DSC加热曲线(a)和TGA曲线(b)的对比。Figure 1 is a comparison of the DSC heating curve (a) and the TGA curve (b) of the catalyst bicyclic guanidine acetate (HTBD-OAc) and TBD in the present invention.
图2为以苯甲醇为溶剂，生成的产物乳酸苄酯的核磁共振氢谱图。Figure 2 shows the hydrogen nuclear magnetic resonance spectrum of the product benzyl lactate using benzyl alcohol as the solvent.
图3为乳酸苄酯标样与以苯甲醇为溶剂，醋酸双环胍盐催化聚乳酸生成的主要产物的气相色谱(a)和质谱(b)对比图。Figure 3 is a comparison of the gas chromatography (a) and mass spectrum (b) of the benzyl lactate standard sample and the main product produced by polylactic acid catalyzed by bicyclic guanidine acetate using benzyl alcohol as the solvent.
具体实施方式Detailed ways
下面以具体的实施例对本发明进行说明。The present invention will be described below with specific examples.
下列实施例中所述的气相色谱分析方法为：The gas chromatography analysis method described in the following examples is:
采用岛津(上海)商贸有限公司GC 2010plus气相色谱分析仪，对PLA反应产物的产率进行测定。其柱温为100℃，以10℃/min的速率升温至280℃，N2作为保护气氛，载气流量为3ml/min分流进样，进样量为1μL。The yield of PLA reaction product was measured using Shimadzu (Shanghai) Trading Co., Ltd. GC 2010plus gas chromatography analyzer. The column temperature is 100°C and is heated to 280°C at a rate of 10°C/min.N2 is used as a protective atmosphere. The carrier gas flow is 3ml/min for split injection and the injection volume is 1μL.
实施例1Example 1
将5g有机碱1,5,7-三叠氮双环(4.4.0)癸-5-烯(TBD)溶解在去离子水中，随后通过恒压滴液漏斗往TBD水溶液中滴加浓度为4％的醋酸水溶液，控制TBD与醋酸的摩尔比为1:1，30℃搅拌反应12h后得到目标产物。旋转蒸发去除溶液中的水后，将固体产品置入真空干燥箱中干燥48h，得到白色固体产品即为醋酸双环胍盐，称量得重量6.8g，产率为95.1％。对醋酸双环胍盐(HTBD-OAc)和有机碱(TBD)进行差示扫描量热法(DSC)分析和热重分析(TGA)。Dissolve 5g of the organic base 1,5,7-triazidobicyclo(4.4.0)dec-5-ene (TBD) in deionized water, and then add dropwise to the TBD aqueous solution through a constant pressure dropping funnel at a concentration of 4% Acetic acid aqueous solution, control the molar ratio of TBD to acetic acid to 1:1, stir and react at 30°C for 12 hours to obtain the target product. After the water in the solution was removed by rotary evaporation, the solid product was placed in a vacuum drying oven and dried for 48 hours to obtain a white solid product, which is bicyclic guanidine acetate. The weight was 6.8g, and the yield was 95.1%. Differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA) were performed on bicyclic guanidine acetate (HTBD-OAc) and organic base (TBD).
所述的DSC方法为：使用型号为DSC Q20(TA Instruments,USA)，在氮气氛围中采取两次升温。第一次升温以10℃/min的速度从40℃加热至220℃，高温停留1min，再以10℃/min的速度从220℃降温至40℃，低温停留1min，第二次升温以10℃/min的速度从40℃加热至220℃，高温停留1min。The DSC method is as follows: using model DSC Q20 (TA Instruments, USA), and raising the temperature twice in a nitrogen atmosphere. The first temperature rise is from 40°C to 220°C at a rate of 10°C/min, the high temperature stays for 1 minute, and then the temperature is lowered from 220°C to 40°C at a rate of 10°C/min, and the low temperature stays for 1 minute. The second temperature increase is at 10°C. Heating from 40℃ to 220℃ at a speed of /min, and staying at high temperature for 1 minute.
所述的TGA方法为：热重分析用于测定催化剂的热分解情况，使用型号是TGAQ550，在氮气氛围中，样品以10℃/min的速率从25℃加热至600℃。The TGA method is: thermogravimetric analysis is used to measure the thermal decomposition of the catalyst. The model used is TGAQ550. In a nitrogen atmosphere, the sample is heated from 25°C to 600°C at a rate of 10°C/min.
醋酸双环胍盐(HTBD-OAc)和有机碱(TBD)的DSC加热曲线(a)和TGA曲线(b)如图1所示。DSC结果表明，与TBD相比，HTBD-OAc的熔点提升到了155℃。TGA曲线表明，与TBD相比，HTBD-OAc的热稳定性更好，大约在200℃时才开始明显失重，说明HTBD-OAc可以稳定存在于醇解反应中。The DSC heating curve (a) and TGA curve (b) of bicyclic guanidine acetate (HTBD-OAc) and organic base (TBD) are shown in Figure 1. DSC results show that compared with TBD, the melting point of HTBD-OAc is increased to 155°C. The TGA curve shows that compared with TBD, HTBD-OAc has better thermal stability and only starts to lose weight obviously at about 200°C, indicating that HTBD-OAc can stably exist in the alcoholysis reaction.
实施例2Example 2
向50mL磁力搅拌高压反应釜中加入1g PLA，7.5g甲醇，50mg醋酸双环胍盐(实例1制备)。以160℃的温度反应2h，反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸甲酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸甲酯的产率为95.6％。Add 1g PLA, 7.5g methanol, and 50mg bicyclic guanidine acetate (prepared in Example 1) into a 50mL magnetically stirred high-pressure reaction kettle. React at 160°C for 2 hours. After the reaction is completed, the reaction solution is cooled to room temperature and filtered under reduced pressure. The unreacted PLA residue is separated and dried in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product methyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of methyl lactate was analyzed to be 95.6%.
实施例3Example 3
向50mL磁力搅拌高压反应釜中加入1g PLA，7.5g乙醇，50mg醋酸双环胍盐(实例1制备)。以160℃的温度反应2h，反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸乙酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸乙酯的产率为94.4％。Add 1g PLA, 7.5g ethanol, and 50mg bicyclic guanidine acetate (prepared in Example 1) into a 50mL magnetically stirred high-pressure reaction kettle. React at 160°C for 2 hours. After the reaction is completed, the reaction solution is cooled to room temperature and filtered under reduced pressure. The unreacted PLA residue is separated and dried in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product ethyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of ethyl lactate was analyzed to be 94.4%.
实施例4Example 4
向50mL磁力搅拌高压反应釜中加入1g PLA，7.5g丙醇，50mg醋酸双环胍盐(实例1制备)。以160℃的温度反应2h，反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸丙酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸丙酯的产率为93.1％。Add 1g PLA, 7.5g propanol, and 50mg bicyclic guanidine acetate (prepared in Example 1) into a 50mL magnetically stirred high-pressure reaction kettle. React at 160°C for 2 hours. After the reaction is completed, the reaction solution is cooled to room temperature and filtered under reduced pressure. The unreacted PLA residue is separated and dried in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product propyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of propyl lactate was analyzed to be 93.1%.
实施例5Example 5
向50mL磁力搅拌高压反应釜中加入1g PLA，7.5g丁醇，50mg醋酸双环胍盐(实例1制备)。以160℃的温度反应2h，反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸丁酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸丁酯的产率为92.9％。Add 1g PLA, 7.5g butanol, and 50mg bicyclic guanidine acetate (prepared in Example 1) into a 50mL magnetically stirred high-pressure reaction kettle. React at 160°C for 2 hours. After the reaction is completed, the reaction solution is cooled to room temperature and filtered under reduced pressure. The unreacted PLA residue is separated and dried in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product butyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of butyl lactate was analyzed to be 92.9%.
实施例6Example 6
向50mL磁力搅拌高压反应釜中加入1g PLA，7.5g异戊醇，50mg醋酸双环胍盐(实例1制备)。以160℃的温度反应3h，反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸异戊酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸异戊酯的产率为92.3％。Add 1g PLA, 7.5g isoamyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) into a 50mL magnetically stirred high-pressure reaction kettle. React at 160°C for 3 hours. After the reaction is completed, the reaction solution is cooled to room temperature and filtered under reduced pressure. The unreacted PLA residue is separated and dried in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product isoamyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of isoamyl lactate was 92.3%.
实施例7Example 7
向50mL单口烧瓶中加入1g PLA，7.5g异辛醇，50mg醋酸双环胍盐(实例1制备)，并置于160℃的油浴中持续搅拌反应3h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸异辛酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸异辛酯的产率为91.8％。Add 1g PLA, 7.5g isooctyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 160°C and continue stirring for 3 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product, isooctyl lactate, was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of isooctyl lactate was 91.8%.
实施例8Example 8
向50mL单口烧瓶中加入1g PLA，7.5g正十二醇，50mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸月桂醇酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸月桂醇酯的产率为93.2％。Add 1g PLA, 7.5g n-dodecanol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product lauryl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of lauryl lactate was 93.2%.
实施例9Example 9
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为94.4％。乳酸苄酯的核磁共振氢谱图如图2所示，气相色谱图如图3(a)所示，质谱图如图3(b)所示。Add 1g PLA, 7.5g benzyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 94.4%. The proton nuclear magnetic resonance spectrum of benzyl lactate is shown in Figure 2, the gas chromatogram is shown in Figure 3(a), and the mass spectrum is shown in Figure 3(b).
实施例10Example 10
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于140℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为71.2％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为57.8％。Add 1g PLA, 7.5g benzyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 140°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA was 71.2%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 57.8%.
实施例11Example 11
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于160℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为93.4％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为90.6％。Add 1g PLA, 7.5g benzyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 160°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA was 93.4%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 90.6%.
实施例12Example 12
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于200℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为91.4％。Add 1g PLA, 7.5g benzyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 200°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 91.4%.
实施例13Example 13
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应0.5h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为68.7％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为62.5％。Add 1g PLA, 7.5g benzyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 0.5h. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA was 68.7%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 62.5%.
实施例14Example 14
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应1h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为88.4％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为85.2％。Add 1g PLA, 7.5g benzyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 1 hour. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA was 88.4%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 85.2%.
实施例15Example 15
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应3h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为92.8％。Add 1g PLA, 7.5g benzyl alcohol, and 50 mg bicyclic guanidine acetate (prepared in Example 1) to a 50 mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 3 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 92.8%.
实施例16Example 16
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，25mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为85.5％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为79.1％。Add 1g PLA, 7.5g benzyl alcohol, and 25mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA was 85.5%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 79.1%.
实施例17Example 17
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，75mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为92.9％。Add 1g PLA, 7.5g benzyl alcohol, and 75mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 92.9%.
实施例18Example 18
向50mL单口烧瓶中加入1g PLA，7.5g苯甲醇，100mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为92.6％。Add 1g PLA, 7.5g benzyl alcohol, and 100mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 92.6%.
实施例19Example 19
向50mL单口烧瓶中加入1g PLA，5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为93.6％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为89.4％。Add 1g PLA, 5g benzyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA was 93.6%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 89.4%.
实施例20Example 20
向50mL单口烧瓶中加入1g PLA，10g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为93.1％。Add 1g PLA, 10g benzyl alcohol, and 50 mg bicyclic guanidine acetate (prepared in Example 1) to a 50 mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 93.1%.
实施例21Example 21
向50mL单口烧瓶中加入1g PLA，12.5g苯甲醇，50mg醋酸双环胍盐(实例1制备)，并置于180℃的油浴中持续搅拌反应2h。反应结束后将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，PLA的转化率为100％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出乳酸苄酯的产率为92.4％。Add 1g PLA, 12.5g benzyl alcohol, and 50mg bicyclic guanidine acetate (prepared in Example 1) to a 50mL one-neck flask, and place it in an oil bath at 180°C and continue stirring for 2 hours. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rate of PLA is 100%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatograph using an external standard method, and the yield of benzyl lactate was analyzed to be 92.4%.
实施例22Example 22
通过催化剂循环实验评估该催化剂的再生性能，具体操作为将降解反应液减压抽滤分离出PLA残留物，加入去离子水萃取，取上清液蒸干水分，并在60℃的真空烘箱中干燥12h，得到醋酸双环胍盐的苯甲醇溶液。补充新鲜的苯甲醇溶液，使其质量达到实施例9所需苯甲醇和醋酸双环胍盐的总质量，再加入1g PLA颗粒进行实验。醋酸双环胍盐重复此操作使用5次后，仍保持较高活性，乳酸苄酯的产率为92％。The regeneration performance of the catalyst was evaluated through a catalyst circulation experiment. The specific operation was to separate the PLA residue from the degradation reaction solution under reduced pressure, add deionized water for extraction, evaporate the supernatant to dryness, and place it in a vacuum oven at 60°C. After drying for 12 hours, a benzyl alcohol solution of bicyclic guanidine acetate salt was obtained. Supplement fresh benzyl alcohol solution so that its mass reaches the total mass of benzyl alcohol and bicyclic guanidine acetate required in Example 9, and then add 1 g of PLA particles to conduct the experiment. After repeating this operation for 5 times, bicyclic guanidine acetate still maintained high activity, and the yield of benzyl lactate was 92%.
对比例1Comparative example 1
分别在2个50mL单口烧瓶中加入相同摩尔的醋酸双环胍盐和有机碱TBD，并以实施例9的反应条件，反应2h。反应结束后分别将反应液冷却至室温并减压抽滤，分离出未反应的PLA残留物，并在真空干燥箱中干燥至恒重。在此条件下，醋酸双环胍盐和有机碱TBD催化PLA苯甲醇醇解的转化率均为100％。反应产物乳酸苄酯采用外标法在气相色谱分析仪中进行定量分析，分析出醋酸双环胍盐催化PLA醇解，乳酸苄酯产率为94.1％，有机碱TBD催化乳酸苄酯产率为86.2％。由此看出，醋酸双环胍盐的催化活性更高。The same moles of bicyclic guanidine acetate and organic base TBD were added to two 50 mL single-necked flasks respectively, and the reaction was carried out for 2 hours under the reaction conditions of Example 9. After the reaction, the reaction solution was cooled to room temperature and filtered under reduced pressure to separate the unreacted PLA residue and dry it in a vacuum drying oven to constant weight. Under these conditions, the conversion rates of benzyl alcoholysis of PLA catalyzed by bicyclic guanidine acetate and organic base TBD were both 100%. The reaction product benzyl lactate was quantitatively analyzed in a gas chromatography analyzer using the external standard method. The analysis showed that bicyclic guanidine acetate catalyzed the alcoholysis of PLA. The yield of benzyl lactate was 94.1%, and the yield of benzyl lactate catalyzed by organic base TBD was 86.2. %. It can be seen that the catalytic activity of bicyclic guanidine acetate is higher.
本发明提供了一种醋酸双环胍盐催化废弃聚乳酸醇解的方法。具体实现该技术方案的途径有很多，以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下,还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。本实施例中未明确的各组成部分均可用现有技术加以实现。The invention provides a method for the alcoholysis of waste polylactic acid catalyzed by bicyclic guanidine acetate. There are many ways to specifically implement this technical solution. The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in this technical field, without departing from the principles of the present invention, they can also make Several improvements and modifications, these improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented using existing technologies.
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| CN202311493592.0ACN117550969A (en) | 2023-11-10 | 2023-11-10 | A method for metal-free bicyclic guanidine acetate to catalyze the alcoholysis of waste polylactic acid |
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| CN202311493592.0ACN117550969A (en) | 2023-11-10 | 2023-11-10 | A method for metal-free bicyclic guanidine acetate to catalyze the alcoholysis of waste polylactic acid |
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