BR102016015522A2 - ENZYMATIC PROCESS FOR ETHYLENE TEREPHALATE POST CONSUMPTION VIA GLYCOLYSIS REACTION, POST-CONSUME POLY (ETHYLENE TEREPHALATE) RECYCLING PROCESS, AND RECYLENED ETHYLENE POLY - Google Patents

Abstract

The present invention relates to an enzymatic process of post consumer poly (ethylene terephthalate) depolymerization via glycolysis reaction. This invention also relates to a process for recycling post consumer polyethylene terephthalate and the recycled polyethylene terephthalate obtained by said process.

Description

(54) Title: ENZYMATIC PROCESS OF DEPOLIMERIZATION OF POLY (ETHYLENE TEREFTALATE) POST CONSUMPTION THROUGH GLYCOLYSIS REACTION, PROCESS FOR RECYCLING POLY (ETHYLENE TEREFTALATE) POST-CONSUMPTION, AND POLY (ETHYLATE TYLEFTALATE). C08J 11/10; C08J 11/24; C08G 63/88; B29B 17/04 (52) CPC: C08J 11/105, C08J 11/24, C08G 63/88, B29B 17/0412 (73) Owner (s): PETRÓLEO BRASILEIRO S.A.

-PETROBRAS (72) Inventor (s): ALINE MACHADO DE CASTRO; ADRIANO CARNIEL DE OLIVEIRA; ÉRIKA DE ARAÚJO VALONI; DANIELLE ALTOMARI TEIXEIRA; CÉSAR REZENDE DA MOTTA (57) Abstract: The present invention is related to an enzymatic process of depolymerization of poly (ethylene terephthalate) post-consumption via glycolysis reaction. This invention also relates to a process for recycling post-consumer poly (ethylene terephthalate) and the recycled poly (ethylene terephthalate) obtained by said process.

/ 12 “ENZYMATIC PROCESS OF DEPOLIMERIZATION OF POLY (ETHYLENE TEREFTALATE) POST-CONSUMPTION THROUGH GLYCOLYSIS REACTION, PROCESS FOR RECYCLING POLY (ETHYLENE TEREFTALATE) POST-CONSUMPTION, AND POLY (ETHYLENE TEREFTALATE)”

FIELD OF THE INVENTION [0001] The present invention relates to an enzymatic process of depolymerization of post-consumption poly (ethylene terephthalate) via glycolysis reaction, to a process for recycling post-consumption poly (ethylene terephthalate) and to poly ( resulting recycled ethylene terephthalate).

BACKGROUND OF THE INVENTION [0002] Poly (ethylene terephthalate), better known as PET, is a type of plastic widely used in the manufacture of containers that are part of the daily life of the majority of the population, since the PET container is commonly used to pack liquids, from medicines to drinks. In the case of beverages, especially carbonated drinks, PET bottles are usually used due to their reduced gas permeability, when compared to other polymers used in the manufacture of packaging. Poly (ethylene terephthalate) can also be found in other types of packaging and in other sectors of the industry, such as textiles, which use the material as a raw material for the manufacture of fabrics, [0003] From a chemical point of view, PET is a thermoplastic polymer formed by the reaction between terephthalic acid (TPA) and ethylene glycol. One of the great advantages of PET is that it can be reprocessed several times by the same or another transformation process, facilitating and favoring its recycling process and continuous use in the production chain.

[0004] For this reason, PET is one of the most recycled plastics in the world. Its recycling has numerous advantages over other packaging in the

2/12 point of view of the energy consumed, water consumption, environmental impact, social benefits, among others.

[0005] But, despite being a recyclable product and with low production cost, inadequate manufacture and disposal make the PET container a huge danger to the environment and human health. [0006] The impacts of post-consumption are caused by containers sent to landfills and mainly by those that are disposed of directly in nature. In the case of properly disposed containers, we have the impacts caused by the activity of collecting and transporting waste, mainly atmospheric emissions (CO ₂ ). In addition, landfills are increasingly distant from large cities and there is a chronic problem of lack of space to dispose of the waste produced. The cost of collecting and disposing of waste is increasingly high. In this way, several resources that could be invested in health, education, security, end up subsidizing this increase in expenses with the continuously generated waste.

[0007] In the event that PET containers are not disposed of properly and are disposed of directly in nature, there is an even more serious problem. PET containers are usually destined for rivers, worsening water pollution and the problem of flooding. Plastic takes more than 100 years to decompose and can even cause biodiversity loss. Plastic fragments can be consumed by animals, leading them to death. The impact of incorrect disposal can be seen even in the oceans, where studies indicate that much of the water is already contaminated.

[0008] Thus, there are several studies carried out today aiming at recycling processes for the reuse of post-consumption PET container material for the synthesis of a new polymer. This reuse can represent great economic advantages for the companies that manufacture this polymer, reducing / 12 the dependence on new inputs of fossil origin.

[0009] WO 2014/079844, for example, describes a process of degradation of crushed PET bottles via hydrolysis reaction, employing a thermobifida cellulosilytica DSM44535 cutinase as a biocatalyst.

[00010] Kim and Song's article (Fibers and Polymers, 2006, vol. 7, p. 339343) evaluates different commercial lipases for the treatment of PET-based textile parts, via the hydrolysis process.

[00011] The article by Muller et al. (Macromolecules, 2009, vol. 42, p. 51285138) investigates different commercial lipases in hydrolysis processes of PET samples from bottles and in the form of pellets.

[00012] However, the aforementioned documents perform the depolymerization of PET via hydrolysis reaction, in which the main product is typically terephthalic acid (TPA) which, upon returning to the polymerization process, still needs to be esterified with ethylene glycol (esterification reactions ) in order to reach bishydroxyethylene terephthalate (BHET) in a next step and then proceed with the polymerization process for the synthesis of new PET.

[00013] As another drawback, when hydrolysis processes are adopted, depolymerization products need to be recovered from the liquid phase to then proceed to the repolymerization process, since the presence of water is undesirable in the esterification reactions.

[00014] In order to overcome these problems, studies were developed in an attempt to obtain optimized processes for the depolymerization reaction of PET containers.

[00015] In this sense, the Brazilian patent document Pl 0605201-0 teaches a method for obtaining PET oligomers, such as bishhydroxy-ethylene terephthalate (BHET) and bis-hydroxy-propylene terephthalate (BHPT), a from a chemical process through the PET glycolysis reaction, using acetate

4/12 zinc as a catalyst. The fact of carrying out a glycolysis reaction has advantages, in that the BHET obtained can be used in the repolymerization process for the synthesis of new PET at a more advanced stage of the process.

[00016] Another advantage lies in the fact that, in glycolysis reactions, ethylene glycol is the liquid phase, which can be directly used in the repolymerization process.

[00017] Similarly, WO 00/47659 discloses a process for depolymerizing and purifying contaminated post-consumer polyester via the glycolysis reaction. This document presents as suitable catalysts, known transesterification catalysts, such as salts of manganese, zinc, antimony, titanium, tin or germanium, which increase the rate of glycolysis. [00018] However, the chemical process employing metallic or alkaline catalysts described above is disadvantageous, since in addition to causing environmental impacts, such catalysts remain in the product mixture obtained, and may interfere with the repolymerization process.

[00019] Therefore, there is still a need to provide an optimized post-consumer PET depolymerization process that is safer, more economical and with less environmental impact.

[00020] As will be further detailed below, the present invention provides a practical and efficient solution to the problems of the prior art described above.

SUMMARY OF THE INVENTION [00021] The present invention relates to a post-consumption enzymatic process of depolymerization of poly (ethylene terephthate) via the glycolysis reaction. This invention also relates to a process for recycling post-consumer poly (ethylene terephthalate) and the recycled poly (ethylene terephthate) obtained by said process.

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DETAILED DESCRIPTION OF THE INVENTION [00022] The present invention relates to a post-consumption enzymatic depolymerization process of poly (ethylene terephthalate) via the glycolysis reaction, in which the product stream obtained at the end of the process is enriched with bis terephthalate. -hydroxy-ethylene (BHET), which can be reused in a new PET repolymerization process.

[00023] This reuse represents surprising advantages since the main product obtained in PET depolymerization reactions is typically terephthalic acid which, returning to the polymerization process, needs to be further esterified with ethylene glycol (esterification reactions) to, in a next step, if you arrive at BHET.

[00024] In contrast, in the depolymerization process of the present invention, the final product stream obtained is already enriched in bishhydroxy-ethylene terephthalate (BHET), which can be reused in a more advanced stage of the process for recycling post-consumer PET. for the synthesis of a new PET, thus reducing energy costs, as well as dependence on p-xylene from third parties, which is used as an input for the synthesis of terephthalic acid.

[00025] The enzymatic PET depolymerization process proposed here is carried out in a stirred tank reactor, preferably being a batch process conducted in a CSTR type reactor, and optionally employs an initial pretreatment step.

[00026] When there is no pre-treatment, the reaction is conducted using crude poly (ethylene terephthalate), whereas when the optional pre-treatment step is used, the process is carried out using poly (terephthalate) fragments ethylene), which are subjected to washing or dressing. When washing, the PET fragments are washed with an aqueous solution containing a non-surfactant

6/12 ionic, such as tween-80, followed by washing with water. In the sauce, the PET fragments are exposed to the ethylene glycol solvent, or mixtures of this with other alcohols for a short period of 10 to 30 min at high temperatures ranging between 100 and 130 ° C, or for longer periods of 12 to 24 hours in milder temperatures varying between 20 and 80 ° C.

[00027] For the depolymerization reaction of poly (ethylene terephthalate) via glycolysis reaction, the crude poly (ethylene terephthalate) or pre-treated PET fragments are first added in the reactor, with ethylene glycol as solvent. Thereafter, the temperature is adjusted and stabilized at the value of interest, preferably from 20 to 100 ° C, and more preferably from 30 to 90 ° C, under atmospheric pressure and agitation at speeds preferably between 20 and 300 rpm. After adjusting these parameters, a catalyst load comprising one or more enzymes is added to the reactor and the glycolysis reaction begins.

[00028] Suitable enzyme catalysts include commercially available cutinases and lipases, preferably Novozym 51032®, from Novozymes, which corresponds to a cuticase of Humicola insolens expressed in Aspergillus, and Lipozyme CALB®, Candida antarctica lipase B. The catalyst load used can vary according to the type of enzyme (s) used and is preferably around 0.01 to 1.0 g / gPET, more preferably around 0.01 to 0, 5 g / gPET.

[00029] After the period of approximately 2 to 30 days has elapsed, preferably from 7 to 28 days, a final product stream comprising terephthalic acid (TPA), monohydroxyethylene terephthalate (MHET) and bishydroxy-terephthalate ethylene (BHET) is obtained, which is enriched with bis-hydroxyethylene terephthalate (BHET). A final product chain “enriched in BHET” means a final product chain comprising BHET in concentrations that vary

7/12 from 2 to 85 pmol / L, which represents a percentage of about 30 to 95% BHET of the total end products of the reaction. An esterification percentage above 70% is still verified at the end of that process.

[00030] The present invention is also directed to a process for recycling post-consumer poly (ethylene terephthalate) via glycolysis reaction which comprises, in addition to the steps described here for the enzymatic depolymerization process of poly (ethylene terephthalate) post -consumption, the additional step of using the final product chain obtained in said poly (ethylene terephthalate) depolymerization process in a more advanced step in the polymerization process of a recycled PET (repolymerization). This reuse provides not only energy gains, but also economic, environmental, health and safety.

[00031] The present invention also relates to the recycled poly (ethylene terephthalate) itself, obtained by the process described and claimed herein.

[00032] The following examples illustrate the various embodiments of the present invention.

Examples

1. Glycolysis of crude PET bottle [00033] Under stirring at 150 rpm at 37 ° C, the enzyme Novozym51032® (NZ) or the lipase B enzyme from Candida antarctica (CALB) was placed in contact with PET fragments from chopped bottles, having ethylene glycol as the solvent. By adding a catalyst load of 0.1 g / gPET, after 7 and 14 days, BHET concentrations of 2.75 and 7.08 pmol / L were obtained, respectively. The molar fractions of the main products (TPA, BHET and MHET), for two loads of catalyst and enzymes are shown in Table 1, and compared with the results of hydrolysis reaction, conducted under the same conditions. It is possible to observe that the conduction of the glycolysis reaction in particular with the NZ enzyme led to an enrichment of

8/12 final solution in BHET, so that this became the main product of the reaction, with a load of 0.1 g / gPET. The table also shows that the conduction of the glycolysis stage, instead of hydrolysis, reduced the molar fractions of the compound MHET, which is an intermediary for depolymerization, between BHET and TPA.

Table 1: Molar fractions of the main products of the reactions of glycolysis and hydrolysis.

Enzyme and charge (g / g) Time (days) Glycolysis Hydrolysis TPA BHET MHET TPA BHET MHET NZ-0.1 7 0.677 0.323 0.000 0.475 0.053 0.472 14 0.386 0.614 0.000 0.454 0.161 0.384 NZ-0.5 7 0.649 0.140 0.212 0.539 0.031 0.429 14 0.312 0.417 0.271 0.620 0.032 0.348 CALB-0.1 7 0.631 0.369 0.000 0.752 0.214 0.035 14 0.394 0.315 0.290 0.661 0.306 0.033 CALB-0.5 7 0.409 0.248 0.343 0.613 0.202 0.185 14 0.293 0.311 0.396 0.575 0.249 0.176

2. Glycolysis of PET pre-treated bottle A [00034] PET fragments from bottles were subjected to the following pretreatment:

A. Washing with aqueous solution containing 2% tween-80 for 1h at 50 ° C, followed by washing with water for 1h and drying for 24h.

[00035] Under agitation of 150 rpm at 37 ° C, the enzyme Novozym51032® (NZ) or the enzyme lipase B of Candida antarctica (CALB) was placed in contact with PET fragments from chopped and pre-treated bottles, with ethylene glycol as solvent and catalyst load of 0.1 g / gPET. When pre-treated PET A was used, after 14 days, a BHET concentration of 24.71 pmol / L was obtained and after 28 days, the esterification percentage of the mixture was 87.8%, with the NZ enzyme, The molar fractions of the main products (TPA, BHET and MHET), for two loads of catalyst and enzymes are shown in Table 2. Note that in this case BHET reached 83.3% of the main reaction products, when PET pre -Treated A was put in contact with the NZ enzyme.

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Table 2: Molar fractions and concentrations of the main products of the glycolysis reactions with pre-treated PET A.

Enzyme Time (days) Concentrations i tpmo / L) Frac molar reactions TPA BHET MHET TPA BHET MHET NZ 7 18.66 14.95 0.45 0.548 0.439 0.013 14 6.65 24.71 0.79 0.207 0.769 0.025 21 2.58 18.57 1.93 0.112 0.805 0.084 22 3.14 17.91 1.44 0.140 0.796 0.064 28 1.65 17.61 1.88 0.078 0.833 0.089 CALB 7 9.99 7.87 1.02 0.529 0.417 0.054 14 3.71 9.45 0.00 0.282 0.718 0.000 21 4.32 5.92 1.14 0.380 0.520 0.100 22 2.07 6.29 1.23 0.216 0.656 0.128 28 1.46 5.59 1.48 0.171 0.656 0.174

3. Glycolysis of PET pretreated bottle B [00036] PET fragments from bottles were subjected to the following pretreatment:

B: Sauce in ethylene glycol (proportion 1g PET to 25mL ethylene glycol) for 22 hours at 37 ° C.

[00037] Under stirring at 150 rpm at 37 ° C, the enzyme Novozym51032® (NZ) or the enzyme lipase B of Candida antarctica (CALB) was placed in contact with PET fragments from chopped and pre-treated bottles, with ethylene glycol as solvent and catalyst load of 0.1 g / gPET. When pre-treated PET B was used, after 14 days, BHET concentration of 84.42pmol / L was obtained with the CALB enzyme and after 22 days, 87.6% esterification percentage with the enzyme

NZ. The molar fractions of the main products (TPA, BHET and MHET), for the two enzyme loads are shown in Table 3. Note that in this case BHET reached 81.3% of the main products of the reaction, when the Pre-treated PET B was placed in contact with the NZ enzyme.

Table 3: Molar fractions and concentrations of the main products of the glycolysis reactions with pretreated PET B.

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Enzyme Time (days) Concentrations (pmol / L) Fra ( molar ions TPA BHET MHET TPA BHET MHET NZ 7 12.28 8.65 0.64 0.569 0.401 0.030 14 6.50 10.97 0.00 0.372 0.628 0.000 21 2.76 6.60 1.12 0.263 0.630 0.107 22 0.52 6.84 1.05 0.062 0.813 0.124 28 1.99 6.52 1.83 0.192 0.631 0.177 CALB 7 15.89 31.47 2.15 0.321 0.636 0.043 14 124.22 84.42 8.58 0.572 0.389 0.040 21 4.21 56.80 17.62 0.054 0.722 0.224 22 4.33 60.53 20.66 0.051 0.708 0.242 28 3.88 74.03 32.99 0.035 0.668 0.297

4. Glycolysis of pre-treated PET bottle C [00038] PET fragments from bottles were subjected to the following pretreatment:

C: Sauce in a mixture of ethylene glycol (proportion 1g PET to 25mL ethylene glycol) for 22h at 70 ° C.

[00039] Under stirring at 150 rpm at 37 ° C, the enzyme Novozym51032® (NZ) or Candida antarctica lipase B (CALB) was placed in contact with PET fragments from chopped and pre-treated bottles, with ethylene glycol as solvent and NZ catalyst load of 0.1g / g _PE T · When pre-treated PET C was used, after 14 days, BHET concentration of 15.51pmol / L and 84.3% mixture esterification percentage were obtained , with the NZ enzyme. The concentrations and molar fractions of the main products (TPA, BHET and MHET), for the two enzymes are shown in Table 4. It is noted that in this case BHET reached 80.3% of the main reaction products, when the Pre-treated PET C was placed in contact with the NZ enzyme.

Table 4: Molar fractions and concentrations of the main products of the glycolysis reactions with pre-treated PET C.

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Enzyme Time (days) Concenl tractions (pmol / L) Fra ( molar reactions I TPA BHET MHET TPA BHET MHET NZ 7 1.04 4.78 0.47 0.164 0.762 0.074 14 1.41 9.79 0.99 0.116 0.803 0.081 21 20.81 15.51 2.14 0.395 0.531 0.075 CALB 7 1.31 2.53 1.38 0.255 0.479 0.266 14 1.06 3.67 1.45 0.177 0.593 0.229 21 1.07 4.56 1.82 0.143 0.612 0.245

5. Glycolysis of pre-treated PET bottle D [00040] PET fragments from bottles were subjected to the following pretreatment:

D: Sauce in ethylene glycol solution (proportion 1g PET to 25mL ethylene glycol) for 20 min at 121 ° C.

[00041] Under stirring at 150 rpm at 37 ° C, Novozym51032® (NZ) or Candida antarctica lipase B (CALB) was placed in contact with PET fragments from chopped and pre-treated bottles, with ethylene glycol as solvent and NZ catalyst load of 0.1g / g _PE T · When pre-treated PET D was used, after 14 days, BHET concentration of 35.08ymol / L was obtained and after 21 days, percentage of esterification of the mixture of 85.1%, with the NZ enzyme. The molar fractions of the main products (TPA, BHET and MHET), for the two enzymes are shown in Table 5. Note that in this case, BHET corresponded to 75.4% of the main reaction products, when PET pre -treatment D was placed in contact with the NZ enzyme.

Table 5: Molar fractions and concentrations of the main products of the glycolysis reactions with pre-treated PET D.

Enzyme Time (days) Concenl tractions (pmol / L) Fra < molar breads TPA BHET MHET TPA BHET MHET NZ 7 2.85 22.34 4.35 0.097 0.756 0.147 14 1.84 23.74 5.96 0.059 0.754 0.188 21 1.58 35.08 11.06 0.034 0.742 0.224 CALB 7 1.17 15.86 6.48 0.050 0.675 0.275 14 1.26 12.63 5.80 0.067 0.690 0.243 21 1.60 12.65 12.50 0.060 0.473 0.467

12/12 [00042] As can be seen from the examples above, the enzymatic process of depolymerization of post-consumer PET via the glycolysis reaction is extremely advantageous, since the product stream obtained at the end is enriched in BHET, the which can be reused in the repolymerization process for the synthesis of new PET at a more advanced stage of the process, thus reducing energy costs and making it more economically viable.

[00043] In addition, the dependence on third party inputs, such as p-xylene, necessary for the synthesis of terephthalic acid, which is the raw material in the process of synthesis of polyester (ethylene terephthalate), is reduced . From an environmental and health point of view, the enzymatic process for the depolymerization of PET is safer, since the biocatalyst (enzymes) used is renewable, non-corrosive and biodegradable, and is conducted under milder temperatures and atmospheric pressure. This fact guarantees additional operational security to the unit that will use it on a large scale.

[00044] Numerous variations affecting the scope of protection of this application are permitted. Thus, it reinforces the fact that the present invention is not limited to the particular configurations / embodiments described above.

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Claims (8)

1. Enzymatic depolymerization process of post-consumption poly (ethylene terephthalate) via glycolysis reaction, characterized by understanding the steps of: a) add poly (ethylene terephthalate) and ethylene glycol in a stirred tank reactor; b) adjust the temperature to a value between 20 and 100 ° C and agitation at a speed between 20 and 300 rpm, under atmospheric pressure; and c) add a catalyst charge between 0.01 to 1.0 g / gPET comprising one or more enzymes of the type cutinase, esterase or lipase, in which, after the period of 2 to 30 days, a final stream comprising terephthalic acid (TPA) monohydroxyethylene terephthalate (MHET) and bishydroxyethylene terephthalate (BHET) is obtained, which comprises 30 to 95% BHET of the total reaction products. Process according to claim 1, characterized in that said process is conducted in batch mode in a CSTR type reactor. 3. Post-consumer poly (ethylene terephthalate) depolymerization process according to claim 1 or 2, characterized in that it further comprises, before step a), a pre-treatment step. 4. Post-consumption poly (ethylene terephthalate) depolymerization process according to claim 3, characterized in that said pre-treatment step comprises washing with non-ionic surfactant or sauce with ethylene glycol, or mixtures thereof with other alcohols. Post-consumer poly (ethylene terephthalate) depolymerization process according to any one of claims 1 to 4, characterized in that the temperature set in step b) is between 30 and 90 ° C. 6. Post-consumer poly (ethylene terephthalate) depolymerization process according to any one of claims 1 to 5, characterized by said one or more 4 «· 2/2 more cutinase, esterase and lipase-type enzymes are selected from a Huminase insolens cutinase expressed in Aspergillus; and CALB, Candida antarctica lipase B, respectively. 7. Process for recycling post-consumer poly (ethylene terephthalate), characterized by comprising d) use the final stream comprising 30 to 95% bishydroxyethylene terephthalate (BHET) obtained in step c) of the enzymatic PET depolymerization process, as defined in any one of claims 1 to 6, in the repolymerization of a recycled poly (ethylene terephthalate). 8. Recycled poly (ethylene terephthalate), characterized by being obtained by the process as defined in claim 7. 4 * ·· » 1/1