Chemical Recycling of Polyolefinic Waste to Light Olefins by Catalytic Pyrolysis

Netsch, Niklas; Vogt, Joachim; Richter, Frank; Straczewski, Grazyna; Mannebach, Gerd; Fraaije, Volker; Tavakkol, Salar; Mihan, Shahram; Stapf, Dieter

doi:10.1002/cite.202300078

Cited by 9 publications

(8 citation statements)

References 60 publications

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“…By using PE as a feedstock, the effectiveness of the ISOMET reaction can now be optimized based on controlling the amount of olefins and by-products produced. 21 Consequently, the developed smart pyrolysis of polyethylene at temperatures below 500 °C results in a mixture of saturated and unsaturated hydrocarbons. In detail, the pyrolysis of HDPE plastics was carried out in a 1250 cm 3 , electrically heated, stainless-steel batch reactor in the temperature range of 420-450 °C in nitrogen gas stream for 3 hours, yielding pyrolysis oil and small amounts of gaseous and solid by-products.…”

Section: Resultsmentioning

confidence: 99%

Chemical Open-Loop Recycling of Polyethylene

Farkas,

Albrecht,

Erdélyi

et al. 2024

Preprint

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The scientific challenge currently receiving much attention is the catalytic conversion of non-biodegradable polymers into versatile chemical platform molecules. As a model of a chemical upcycling process, we have developed a homogeneous catalytic system to break down persistent polyethylene waste into valuable chemical intermediates that could ultimately be used to produce important chemical products, including environmentally friendly, biodegradable plastics. In the first step, a smart pyrolysis of polyolefin waste yields oils, containing long-chain olefins as the major components. Then, for the next transformation step, tailored BICAAC-Ru olefin metathesis catalysts were used in combination with an alkene isomerization catalyst (RuHCl(CO)(PPh3)3) for the transformation of the pyrolysis oil to propylene via isomerization metathesis (ISOMET) reaction in ethylene atmosphere. Eventually, translation of the highly efficient single-metal catalyst system enabled ISOMET reaction to a 900 mL reactor setup and repetitive batch experiments could prove the long-term stability of the catalyst system and the highest turn over number (TON = 3800) reported so far for propylene using polyethylene municipal waste feedstock. Propylene content in the gas phase achieved the 20 vol%. Ultimately, these results pave the way for the large-scale applicability of this process as a relevant demonstration of the combined application of adapted catalyst design and chemical engineering optimization with the aim of establishing a multi-dimensional circular economy concept in the chemical industry.

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Section: Resultsmentioning

confidence: 99%

Chemical Open-Loop Recycling of Polyethylene

Farkas,

Albrecht,

Erdélyi

et al. 2024

Preprint

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“…The higher ED may result from the more complex composition incorporating heteroatom-containing polymers like PA6, PET, or PVC. For such thermoplastic blends, Netsch et al report significant polymer interactions during pyrolysis . These interactions lead to differing degradation mechanisms, which could explain the discrepancies between the model and experimentally determined ED.…”

Section: Resultsmentioning

confidence: 99%

“…Pilot-scale experiments were carried out using an electrically heated screw reactor. The experimental setup and procedure are described in detail by Zeller et al and Netsch et al for the pyrolysis of contaminated plastic waste and polyolefin-rich plastic mixtures. ,, The mass balance and ED were derived. The reactor temperature was set to 500 °C.…”

Section: Methodsmentioning

confidence: 99%

Energy Demand for Pyrolysis of Mixed Thermoplastics and Waste Plastics in Chemical Recycling: Model Prediction and Pilot-Scale Validation

Netsch,

Zeller,

Richter

et al. 2024

ACS Sustainable Resour. Manage.

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Pyrolysis of plastic waste is a key technology for closing the anthropogenic carbon cycle. The energy demand (ED) of this endothermic process is a crucial factor to evaluate its benefits compared to established recycling pathways. The pyrolysis ED can be determined experimentally. However, this is elaborate and limited in transferability. Existing models cover virgin plastics or hydrocarbon thermoplastic mixtures on a laboratory scale. Here, a model for calculating the ED of thermoplastic mixtures based on the superposition of virgin polymer data is developed. The material data, such as heat capacity, phase transition enthalpy, and reaction enthalpy, are determined using differential scanning calorimetry. Pilot-scale experiments are performed in a 1 kg/h screw reactor. These experimental data are compared to model calculations. The feedstock-specific ED for pyrolysis is plastic-type independent. It amounts to approximately 4−6% of the feedstocks' net calorific value. The validation shows excellent accordance for virgin plastics and hydrocarbon plastics mixtures. The modeled ED of mixtures including heteroatoms is systematically underestimated, which indicates changes in the degradation mechanism. The model allows for resolving several phenomena contributing to the pyrolysis ED. The simple calculation of the ED with in-depth information on occurring phenomena enables more reliable process design, optimization, and evaluation.

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“…17,18 In recent years, catalytic degradation has attracted increased attention as a viable process for the chemical recycling of polyolefin plastics under mild reaction conditions. 19,20 In previous studies, monofunctional catalysts such as ZSM-5 (ref. 21) and Hbeta 22 were employed for the cracking of polyolefin plastics, yielding substantial non-solid products.…”

Section: Introductionmentioning

confidence: 99%