Plastic pollution has become one of the most pressing environmental issues. Chemical recycling of plastic waste into pyrolysis oils, followed by steam cracking into platform molecules, overcomes the limitations of current recycling processes and is expected to become one of the main routes to boost circularity. However, plastic waste contains large amounts of contaminants, a.o. halogens, heteroatoms (N, S, O, P), and metals. Steam crackers have strict limitations on their maximal concentrations to protect the cracker and product quality. Hence, the contaminants’ concentrations in the pyrolysis oils must be tracked. Waste sorting and pyrolysis processes strongly influence those concentrations, but a detailed model describing their influence and interactions is missing. This project will fill this gap by characterizing several plastic waste feeds, facilitating the upgrading of a waste sorting model. Experimental data on the pyrolysis of identified contaminants and complete waste streams will be gathered in two unique setups fitted with the most advanced characterization techniques. This will allow the development of kinetic models for identified halogen- and heteroatom-containing polymers’ pyrolysis. The models will be combined to describe real-life waste pyrolysis and validated against the experimental data. Finally, combining all models will allow describing the chemical recycling value chain, opening pathways for its optimization, and benefiting involved industries.