Chemical recycling: A critical assessment of potential process approaches

Abstract

Increased media coverage of plastic pollution in the environment and import bans on plastic waste in several countries have resulted in plastic waste becoming one of the most discussed waste streams in recent years. In the European Union (EU), only about one-third of the post-consumer plastic waste is recycled; the rest goes to energy recovery and landfilling in equal parts. In connection to the necessary increase in efforts to achieve the ambitious EU recycling targets, chemical recycling is currently receiving more and more attention. The assumption is that chemical recycling processes could open up new waste streams for recycling and generate valuable raw materials for the chemical industry. Although there exists no legal definition for chemical recycling, there is more or less agreement that it covers the conversion of plastic polymers into their monomers or chemical building blocks. Techniques such as gasification, pyrolysis and liquefaction as well as solvolysis can be used for chemical recycling. So far, only few large-scale plants for chemical recycling exist worldwide. This article presents the different processes by means of examples from (formerly) running installations and their suitability for plastics recycling is assessed. However, to date, only few chemical recycling plants are in continuous operation, and further scientific evidence for the ecological and economic benefits is still necessary for final evaluation.

The environmental performance of plastic packaging waste management in Germany: Current and future key factors

“…The effect of implementing these technologies on environmental impacts of PPWM is widely discussed (Benavides et al., 2017; Civancik‐Uslu et al., 2021; Meys et al., 2020; Möck et al., 2022; Volk et al., 2021). So far, comprehensive LCAs of chemical recycling technologies are missing due to a lack of data on operating plants and their operating conditions (Quicker et al., 2022).…”

Monomer Recycling as Complementary Technology in a Circular Economy

“…In order to integrate a BMR process into a given new network of recycling technologies, its environmental advantage must be demonstrated [31]. While mechanical recycling shows a specific energy consumption and involves the use of additives to maintain physical properties of the recyclates, chemical recycling methods on top also require reactants in the depolymerization reaction, leading to an increased economic as well as ecological effort [12,36]. However, the latter also offers the opportunity to apply established measures to reduce the specific energy consumption by utilizing the released heat of depolymerization reaction for the preheating of the reactants.…”

Upcycling of thermosetting polymers into high-value materials

“…Pyrolysis refers to the thermal degradation of thermoset waste in the range of 300-800 1C. [11][12][13] The objective is to achieve gaseous or liquid small-molecule products to be used as fuels. While tar (a mixture of aromatic hydrocarbons with greater molecular weight greater than benzene) and carbon are also produced, the obtained fuels are often of low value.…”