阅读说明：本技术 一种吡咯烷酮低共熔溶剂的制备及其高效催化多元醇醇解pet的方法 (Preparation of pyrrolidone eutectic solvent and method for efficiently catalyzing polyalcohol alcoholysis of PET (polyethylene terephthalate) by using pyrrolidone eutectic solvent ) 是由 周清 李菲 吕兴梅 晏冬霞 蒋志强 黄俊杰 鲍毅楠 徐俊丽 辛加余 张锁江 于 2021-10-09 设计创作，主要内容包括：本发明涉及一种吡咯烷酮低共熔溶剂的制备及其高效催化多元醇醇解PET的方法,其特征在于以吡咯烷酮及其衍生物与金属盐制备的低共熔溶剂为催化剂,以多元醇为醇解剂,在催化剂用量为PET质量的0.5％-5％,醇解剂用量为PET质量的2-6倍,反应温度为170℃-220℃,常压,反应时间为5min-60min的条件下醇解PET。该方法具有催化剂易于合成,反应时间短,PET降解率高、降解产物可循环利用,过程绿色可循环等优点。(The invention relates to a preparation method of pyrrolidone eutectic solvent and a method for efficiently catalyzing polyalcohol to alcoholyze PET (polyethylene terephthalate), which are characterized in that the eutectic solvent prepared from pyrrolidone and derivatives thereof and metal salt is used as a catalyst, polyalcohol is used as an alcoholysis agent, and PET is subjected to alcoholysis under the conditions that the dosage of the catalyst is 0.5-5% of the mass of PET, the dosage of the alcoholysis agent is 2-6 times of the mass of PET, the reaction temperature is 170-220 ℃, the reaction temperature is normal pressure, and the reaction time is 5-60 min. The method has the advantages of easy synthesis of the catalyst, short reaction time, high PET degradation rate, recyclable degradation products, green and recyclable process and the like.)

1. A method for preparing pyrrolidone eutectic solvent and efficiently catalyzing polyalcohol alcoholysis PET (polyethylene terephthalate) by using the pyrrolidone and derivatives thereof as hydrogen bond donors, using lead acetate, zinc acetate, manganese acetate and cobalt acetate as a catalyst for synthesizing the eutectic solvent of a hydrogen bond acceptor, using ethylene glycol, propylene glycol, butanediol and diethylene glycol as alcoholysis agents, and carrying out alcoholysis reaction at a certain temperature, reaction time and normal pressure according to different mass ratios of the catalyst, PET raw materials and the alcoholysis agents to respectively obtain degraded monomer products of ethylene glycol terephthalate (BHET), propylene glycol terephthalate (BHPT), butylene glycol terephthalate (BHBT), BHET and corresponding oligomer products. Wherein the pyrrolidone and derivatives thereof are 2-pyrrolidone, 1-ethyl-2-pyrrolidone and L-proline; the preparation method of the pyrrolidone eutectic solvent comprises the following steps: mixing and stirring pyrrolidone and derivatives thereof and acetate according to different molar ratios of 4:1-1:2 at the temperature of 80-110 ℃ for 1-3 h to synthesize a transparent and uniform stable phase with a certain viscosity at room temperature, namely the eutectic solvent.

2. The process according to claim 1, wherein the ratio by mass of polyol to PET is from 2:1 to 6: 1.

3. The process according to claim 1, characterized in that the amount of catalyst is 0.5% to 5% by mass of the starting PET.

4. The process of claim 1, wherein the reaction temperature is from 170 ℃ to 220 ℃.

5. The process according to claim 1, wherein the reaction time is from 5min to 60 min.

Technical Field

The invention relates to the technical field of green and clean catalysis, in particular to a novel method for catalyzing polyalcohol alcoholysis PET by using a eutectic solvent prepared from pyrrolidone and derivatives thereof and acetate as raw materials.

Background

Polyethylene terephthalate (PET for short) is a very important plastic material as the most important variety of thermoplastic polyester, and because the bottle made of it has many advantages of no toxicity, anti-seepage, light weight, high production efficiency, etc., it is widely used in beverage packaging. According to published data, the consumption of worldwide PET bottles in 2019 is 2411 ten thousand tons. In China, the consumption of PET in 2020 is nearly one million tons in the major countries consuming polyester plastics. Under the vision of carbon neutralization, the recycling of PET plastics has become a global scientific proposition as one of the most effective ways to reduce carbon emission.

The recycling technology of PET is developed by overlapping methods such as physical circulation, chemical degradation, biological enzymolysis and the like. Among them, the chemical degradation method is favored by the industry in recent years, and most researches are carried out by using the polyol alcoholysis method, and the method can degrade waste PET into oligomers or monomers, and further synthesize regenerated PET or other new polyester materials again, thereby realizing the recycling of resources. According to the American society for Plastic recovery (APR), the emission of carbon dioxide is about 2.23 kg for the production of 1 kg virgin PET plastic, while the emission of carbon dioxide is only 0.91 kg for the production of 1 kg recycled PET plastic. Taking 949 million tons of PET bottle consumption in China in 2020 as an example, if 949 million tons of waste PET bottles can be recycled and used for manufacturing regenerated textiles in theory, 1253 million tons of carbon emission can be reduced compared with textiles produced by using original PET, which is equivalent to one year of carbon emission of 240 million vehicles. Therefore, the chemical method is expected to solve the economic utilization problem of atoms fundamentally and is an effective way for realizing carbon emission reduction. However, the market competition from virgin plastics and the economic constraint of the virgin plastics are bottleneck problems which must be overcome in the process of promoting the industrialization of chemical recovery technology, so that the recycling of waste PET into high value-added products by adopting a simple and efficient method is an important way for realizing the feasibility and the economy of PET chemical recovery.

The method for degrading PET by using polyalcohol not only can prepare monomer ethylene terephthalate (BHET) for synthesizing regenerated PET, but also can produce monomer or oligomer products with specific functional groups by changing the structure of the polyalcohol. The degraded monomer and oligomer obtained by the PET method through the alcoholysis of the polyol can realize the full component utilization, can be used as a plasticizer, a cross-linking agent, a corrosion inhibitor and the like, and have wide application prospects in the production of high-value products such as unsaturated polyester resin, polyurethane, epoxy resin, vinyl ester and the like. Therefore, the polyol alcoholysis of PET is the key to the high-value recycling of PET. However, the technology of the polyol alcoholysis of PET at home and abroad is still imperfect at present. For example, japan, as a representative of environmental protection pioneers, has done much work on the aspect of the innovation of the PET degradation technology, and the chemical recycling PET technology that has been commonly agreed by japan environmental design and two days still adopts the conventional single glycolysis process to selectively extract the intermediate BHET recycled PET resin from PET of polyester fiber or plastic bottle raw material, and does not take into consideration the high-valued PET recycling technology such as other polyol alcoholysis PET process. The reason is that the alcoholysis catalysis efficiency of the catalyst is not high, and long-time high-temperature reaction is needed, so that the energy consumption is increased. Compared with ethylene glycol, the reaction activity of other polyols is lower, so that the design and research of a more efficient polyol degradation catalyst become a core problem of the technology for recycling PET through polyol alcoholysis.

The eutectic solvent is generally a eutectic mixture formed by hydrogen bond donor and hydrogen bond acceptor through hydrogen bond interaction, and has been widely used in recent years due to the advantages of low price, wide sources, biodegradability and the like. At present, a partial eutectic solvent is used as a catalyst for catalyzing alcoholysis reaction of ethylene glycol and achieves higher efficiency, but the problem of low reaction activity of catalyzing other polyols to degrade PET still exists. The efficient and universal eutectic solvent catalyst is developed, the further development of the waste PET high-valued recycling industry can be effectively promoted, the powerful energy is provided for the packaging industry, and the contribution is made to the realization of a rich and sustainable decarburization society.

Disclosure of Invention

Aiming at the problems of low degradation efficiency, deepened product chromaticity, complex byproducts and the like caused by long time in the polyol alcoholysis PET process in the prior art, the invention provides a method for efficiently catalyzing polyol alcoholysis PET by applying a pyrrolidone eutectic solvent. The pyrrolidone and the derivatives thereof are used as hydrogen bond donors and are mixed with the metal salt as a hydrogen bond acceptor, and the synthesized eutectic solvent is used for the PET alcoholysis reaction together with the ethylene glycol, the propylene glycol, the butanediol and the diethylene glycol. The catalyst has high activity when used in the alcoholysis reaction of the PET polyhydric alcohol, and has stable performance and uniform components.

The method for catalyzing the alcoholysis of PET (polyethylene terephthalate) by using the eutectic solvent synthesized by pyrrolidone and derivatives thereof and zinc acetate as raw materials is characterized in that the eutectic solvent synthesized by the pyrrolidone and the derivatives thereof and metal salts such as zinc, manganese and the like is used as a catalyst, the polyol is used as an alcoholysis agent, and the PET is subjected to alcoholysis.

The molar ratio of the pyrrolidone and the derivatives thereof to the eutectic solvent synthesized by taking the metal salt as the raw material is 1:4-2:1, the synthesis temperature is 80-110 ℃, the reaction time is 1-3 h, and the eutectic solvent is obtained until a transparent and uniform phase stable substance with certain viscosity at room temperature appears.

The dosage of the catalyst in the alcoholysis reaction is 0.5-5% of the mass of the PET raw material.

The reaction temperature of the alcoholysis reaction is 170-220 ℃.

The reaction time of catalyzing and depolymerizing PET by taking the pyrrolidone and the derivatives thereof and the metal salt eutectic solvent as the catalyst is 5-60 min.

After the reaction is finished, the degradation rate of PET and the selectivity of the monomer and oligomer products are respectively calculated according to the formulas (1), (2) and (3)

Where A represents the original mass of the added PET and B represents the mass of the undegraded PET.

Compared with the prior art, the method has the following advantages:

1. the addition of the eutectic solvent can greatly accelerate the reaction rate while ensuring mild reaction conditions of the polyol alcoholysis PET process, obviously shorten the reaction time compared with other PET alcoholysis processes, and reduce the process energy consumption;

2. the product has simple composition, the monomer and oligomer ratio is 1:1-9:1, and when the all components are reused for preparing the regenerated polyester product, the energy consumption of repolymerization can be obviously reduced, thereby providing a technical basis for the recycling and high-valued reutilization of the waste PET.

Detailed Description

The present invention is described by the following examples, but the present invention is not limited to the following examples, and variations and implementations are included in the technical scope of the present invention without departing from the spirit of the invention.

The catalysts used in the following examples were synthesized under the conditions shown in the table below until a homogeneous, stable, clear phase was formed.

Example 1

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst a are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is subjected to condensation reflux for 20min under normal pressure. Under these conditions, the degradation rate of PET was 97.0% and the yield of BHBT was 60.7%.

Example 2

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst b are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is condensed and refluxed for 20min under normal pressure. Under these conditions, the degradation rate of PET was 100.0% and the yield of BHBT was 62.7%.

Example 3

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst c are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is condensed and refluxed for 20min under normal pressure. Under these conditions, the degradation rate of PET was 100.0% and the yield of BHBT was 63.9%.

Example 4

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 170 ℃, and the mixture is condensed and refluxed for 30min under normal pressure. Under these conditions, the degradation rate of PET was 17.6% and the yield of BHBT was 15.0%.

Example 5

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst e are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is condensed and refluxed for 20min under normal pressure. Under these conditions, the degradation rate of PET was 99.8% and the yield of BHBT was 47.0%.

Example 6

PET is used as a raw material, 5.0g of PET, 10.0g of butanediol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is subjected to condensation reflux for 15min under normal pressure. Under these conditions, the degradation rate of PET was 92.8% and the yield of BHBT was 45.6%.

Example 7

PET is used as a raw material, 5.0g of PET, 30.0g of butanediol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is subjected to condensation reflux for 15min under normal pressure. Under these conditions, the degradation rate of PET was 100.0% and the yield of BHBT was 67.2%.

Example 8

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is condensed and refluxed for 5min under normal pressure. Under these conditions, the degradation rate of PET was 46.9% and the yield of BHBT was 34.5%.

Example 9

PET is used as a raw material, 5.0g of PET, 25.0g of ethylene glycol and 0.25g (5 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled to be 190 ℃, the normal pressure is realized, and the condensation reflux is carried out for 60 min. Under these conditions, the degradation rate of PET was 100.0% and the yield of BHET was 87.3%.

Example 10

PET is used as a raw material, 5.0g of PET, 25.0g of diethylene glycol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, the normal pressure is realized, and condensation reflux is carried out for 45 min. Under these conditions, the degradation rate of PET was 100.0% and the yield of BHET was 59.1%.

Example 11

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled to be 220 ℃, the normal pressure is realized, and the condensation reflux is carried out for 10 min. Under these conditions, the degradation rate of PET was 100.0% and the yield of BHBT was 62.3%.

Example 12

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.025g (0.5 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, the normal pressure is realized, and the condensation reflux is carried out for 15 min. Under these conditions, the degradation rate of PET was 97.6% and the yield of BHBT was 55.5%.

Example 13

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled to be 180 ℃, the normal pressure is realized, and the condensation reflux is carried out for 30 min. Under these conditions, the degradation rate of PET was 31.3% and the yield of BHBT was 25.8%.

Example 14

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled to be 190 ℃, normal pressure is realized, and condensation reflux is carried out for 30 min. Under these conditions, the degradation rate of PET was 48.4% and the yield of BHBT was 35.0%.

Example 15

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled to be 200 ℃, and the condensation reflux is carried out for 30min under normal pressure. Under these conditions, the degradation rate of PET was 94.9%, and the yield of BHBT was 62.9%.

Example 16

PET is used as a raw material, 5.0g of PET, 25.0g of propylene glycol and 0.20g (1% wt) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 185 ℃, and the condensation reflux is carried out for 60min under normal pressure. Under these conditions, the degradation rate of PET was 98.8% and the yield of BHPT was 68.4%.

Example 17

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.20g (4 wt%) of catalyst d are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is subjected to condensation reflux for 15min under normal pressure. Under these conditions, the degradation rate of PET was 100% and the yield of BHBT was 64.5%.

Example 18

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst f are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is condensed and refluxed for 20min under normal pressure. Under these conditions, the degradation rate of PET was 97.5% and the yield of BHBT was 48.1%.

Example 19

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst are sequentially added into a 50ml three-neck flask, the alcoholysis reaction temperature is controlled at 210 ℃, and the mixture is condensed and refluxed for 20min under normal pressure. Under these conditions, the degradation rate of PET was 100% and the yield of BHBT was 63.0%.

Example 20

PET is used as a raw material, 5.0g of PET, 25.0g of butanediol and 0.10g (2 wt%) of catalyst are sequentially added into a 50ml three-neck flask, the reaction temperature is controlled at 210 ℃, and the mixture is condensed and refluxed for 20min under normal pressure. Under these conditions, the degradation rate of PET was 100.0% and the yield of BHBT was 54.5%.

The above embodiments are illustrative of the present invention, and any simple modification, replacement, combination, or simplification is effective and alternative without departing from the core of the present invention, and is included in the protection scope of the present invention.