Development of a continuous PET depolymerization process as a basis for a back-to-monomer recycling method

Biermann, Lars; Brepohl, Esther; Eichert, Carsten; Paschetag, Mandy; Watts, Marcus; Scholl, Stephan

doi:10.1515/gps-2021-0036

Cited by 28 publications

(30 citation statements)

References 39 publications

(49 reference statements)

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“…To avoid degradation and reduce the influence of contamination, plastic materials can be treated by chemolysis. The RevolPET technology is able to recover the monomer materials [ethylene glycol (EG) and the corresponding salt of terephthalic acid (TA)] in an extrusion process from PET (Biermann et al, 2021). For other polymers and their combinations, pyrolysis offers one possibility to reduce the polymers to olefins and aromates which can be reutilized for the generation of new plastic materials by pyrolysis (Costa et al, 2021).…”

Section: Materials Processing In Usermafasmentioning

confidence: 99%

Increasing resilience of material supply by decentral urban factories and secondary raw materials

Meyer¹,

Görgens²,

Juraschek³

et al. 2023

Front. Manuf. Technol.

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Current production processes are frequently dependent on global supply chains for raw materials and prefabricated inputs. With rising political and global risks, these supply networks are threatened, which leads to a reduction of supply chain resilience. At the same time, urban areas are currently one of the main consumers of products and waste material generators. The raw material sourcing for this consumption commonly takes place in globally connected supply chains due to economy of scale effects. Therefore, cities are especially vulnerable to supply chain disruptions. A recent development which could reduce this vulnerability is the installation of urban factories among other urban production concepts, which can be symbiotically embedded into the urban metabolism to utilize the locally available (waste) materials. This, however, is hampered by the smaller production scale of decentralized urban production facilities, limited knowledge and challenges about the urban material flows and their characteristics. Against this background, we introduce a new factory type which is placed between the primary and secondary industrial sector: An urban secondary raw material factory which utilizes local waste material and other urban material flows for the extraction and refinement of secondary raw materials to supply production sites in its surrounding environment. To enable this small-to medium-scale factory type, the application of new production technologies plays a crucial role. Therefore, this paper proposes an approach for matching relevant potential waste streams to different technologies for waste-to-resource refinement. The applicability of the method for identification and evaluation of suitable technologies regarding their potential to be located in urban environments is demonstrated for plastic and metallic materials. Subsequently, key challenges and characteristics of the new factory type are summarized. With the introduction of this new factory type, the lack of scale effects in urban symbiotic networks is expected to be reduced. In conclusion, challenges such as the data-based management of symbiotic relationships among manufacturing companies are highlighted as still relevant in decentral value chains.

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Section: Materials Processing In Usermafasmentioning

confidence: 99%

Increasing resilience of material supply by decentral urban factories and secondary raw materials

Meyer¹,

Görgens²,

Juraschek³

et al. 2023

Front. Manuf. Technol.

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“…Chemical depolymerization uses chemicals and catalysts to influence the breakdown of PET into its monomers, BHET, MHET, TPA, and EG obtained from glycolysis, DMT from methanolysis, and TPA derivatives from aminolysis. Chemical depolymerization methods include alcoholysis (methanolysis), aminolysis, hydrolysis (steam, mineral acids, water, and alkalis), and glycolysis [ 31 ]. Inorganic catalysts, organocatalysts, and ionic liquids have been used to accelerate depolymerization.…”

Section: Chemical Depolymerizationmentioning

confidence: 99%

Recent Advances in the Chemobiological Upcycling of Polyethylene Terephthalate (PET) into Value-Added Chemicals

Mudondo

Lee

Jeong

et al. 2022

J. Microbiol. Biotechnol.

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Polyethylene terephthalate (PET) is a plastic material commonly applied to beverage packaging used in everyday life. Owing to PET’s versatility and ease of use, its consumption has continuously increased, resulting in considerable waste generation. Several physical and chemical recycling processes have been developed to address this problem. Recently, biological upcycling is being actively studied and has come to be regarded as a powerful technology for overcoming the economic issues associated with conventional recycling methods. For upcycling, PET should be degraded into small molecules, such as terephthalic acid and ethylene glycol, which are utilized as substrates for bioconversion, through various degradation processes, including gasification, pyrolysis, and chemical/biological depolymerization. Furthermore, biological upcycling methods have been applied to biosynthesize value-added chemicals, such as adipic acid, muconic acid, catechol, vanillin, and glycolic acid. In this review, we introduce and discuss various degradation methods that yield substrates for bioconversion and biological upcycling processes to produce value-added biochemicals. These technologies encourage a circular economy, which reduces the amount of waste released into the environment.

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“…They used a twin-screw extruder for reacting solid PET mono-and multilayer flakes with sodium hydroxide pellets to reach degrees of depolymerization up to 97% with an average residence time of 60 s. While polyethylene layers remained intact, the PET depolymerized into disodium terephthalate (DST) and EG. 12 All of these studies on PET saponification represent the growing attention on alkaline hydrolysis of PET. With regard to subsequent TA recovery, these studies usually precipitate TA from its alkaline salt by protonation with the help of a strong acid.…”

Section: Introductionmentioning

confidence: 99%

“…A different approach is reported by Biermann and Brepohl et al. They used a twin-screw extruder for reacting solid PET mono- and multilayer flakes with sodium hydroxide pellets to reach degrees of depolymerization up to 97% with an average residence time of 60 s. While polyethylene layers remained intact, the PET depolymerized into disodium terephthalate (DST) and EG …”

Section: Introductionmentioning

confidence: 99%

Precipitation of Terephthalic Acid from Alkaline Solution: Influence of Temperature and Precipitation Acid

Müller

Heck

Stephan

et al. 2023

Ind. Eng. Chem. Res.

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Back-to-monomer recycling offers a perspective for yet unrecyclable polyethylene terephthalate (PET) waste like textile fibers, multilayer food trays, or brittle bottles. In this context, depolymerization by alkaline hydrolysis is a promising method which demands for consecutive acidic or electrochemical precipitation to recover terephthalic acid (TA). This study investigates the influence of temperatures up to 90 °C and acidification agents on precipitation of TA from aqueous disodium terephthalate solution. The experiments were conducted with a model reactant prepared from purified TA dissolved in sodium hydroxide. The influence on the TA crystal size and morphology affecting further processing, such as filterability and flowability, are discussed. In comparison to commonly used bulk chemical sulfuric acid, experiments with acetic acid were conducted. An enhanced solubility by diluted acetic acid and elevated precipitation temperature lead to significantly larger crystals. Likewise, filtration times for sulfuric acid can be shortened by more than 80% upon increasing the precipitation temperature from 36.5 to 90 °C. The comparison of yield in dependence of pH for different precipitation acids (phosphoric, hydrochloric, oxalic, citric) emphasizes the effect of solid product removal since even weaker acids than TA lead to a reasonable yield of up to 78% for acetic acid. These results offer a perspective and show the necessity for optimizing precipitation with respect to product quality and processability.

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Development of a continuous PET depolymerization process as a basis for a back-to-monomer recycling method

Cited by 28 publications

References 39 publications

Increasing resilience of material supply by decentral urban factories and secondary raw materials

Increasing resilience of material supply by decentral urban factories and secondary raw materials

Recent Advances in the Chemobiological Upcycling of Polyethylene Terephthalate (PET) into Value-Added Chemicals

Precipitation of Terephthalic Acid from Alkaline Solution: Influence of Temperature and Precipitation Acid

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