Plastic recycling is one of the main challenges of the energy transition. Plastics are widely used in many fields (packaging, building and construction, consumer products, …) and generate a huge quantity of waste [1]. They are based on various polymer resins (PE, PP, PVC, …) to which organic and/or inorganic additives (fillers, plasticizers, flame retardants, ....) are added. As mechanical recycling often results in degraded plastic properties, chemical recycling (dissolution, depolymerization or conversion) is a viable alternative to develop a circular economy. Nevertheless, contaminants are still an issue during these processes, and their characterization at trace levels is a great challenge.

Pyrolysis is a promising solution for mixed plastic waste recycling. However, the plastic pyrolysis oil (PPO) must be upgraded before chemical processes due to a significant amount of N, O, Cl, Fe, Na and Si [2]. Chlorine, mainly originated from chlorine-containing polymers (polyvinyl chloride, PVC) or from a variety of additives, can generate HCl, which is corrosive to processing installations. A second example is silicon, who is known to be a severe poison for downstream catalysts and need to be eliminated during upgrading. In the first part of this work, we propose a strategy using gas chromatography (GC) coupled to ICP-MS/MS with a H2 mass shift mode to identify and quantify Cl [3] and Si [4] species in approximatively 10 PPO feedstocks and effluents after upgrading. GCxGC-TOF/MS was also used to identify the remaining unknown species.

Another approach for chemical recycling is the dissolution of polymers (such as PVC). However, the presence of now banned additives as phthalates or P based flame retardants must be identified and quantified to meet the future specifications. To overcome this challenge, a novel non-targeted approach based on two-dimensional liquid chromatography (2D-LC) coupled to electrospray high resolution mass spectrometry (ESI-HRMS) and to ICP-MS/MS was applied to 8 post-consumer PVC from various waste recycling plants. Numerous organophosphate flame retardants and their degradation products were respectively identified and quantified with a very good mass balance comparing to the P total content.