Plastic fraction represents around 30% of the total Waste Electric and Electronic Equipment (WEEE) and is composed by a great variety of polymers (ABS, PS, HIPS, PE/PP, PC, etc..) and additives. Among the latter Bromine Flame Retardants (BFR) are substances of great environmental and health concern that require to be safely disposed.
Mechanical recycling processes are focused on recovering the majority of polymers with a suitable quality to be used directly for market applications, reducing the production volume of new virgin polymers. These recycling processes also produce waste in the different stages of the sorting, classification and purification scheme, having a highly heterogeneous chemical composition that prevents its use as raw material for the recovery of polymers through new recycling processes, such as CreaSolv® or EXTRUCLEAN that are being developed in the NONTOX project.
Accordingly, the plastic wastes from sorting and classification processes together with residues from CreaSolv® represent a significant volume of plastic waste that, in the absence of recycling alternatives, has incineration or landfilling as the only current alternatives for use or disposal.
NONTOX project includes a dedicated Work Package (WP3) to develop a thermochemical process (TRL5) able to convert the mentioned waste plastic fraction into halogen-free components and with a suitable composition for being used as petrochemical feedstocks, industrial solvents or advanced fuels.
Figure 1. Schematic flow diagram of the experimental setup used for the plastics pyrolysis experiments (both thermal and catalytic).
The results obtained during the first half (June 2019 – November 2020) of the project were focused on the catalytic pyrolysis process (Fig.1) and have confirmed their potential to quantitatively convert these plastics into liquids with an important reduction in the halogen content compared to the plastics fed to the process. Some of these results are illustrated in figure 2:
Figure 2. Oil Br content vs oil mass yield (wt.%, referred to the raw plastic sample in ash free basis), in thermal (550ºC) and catalytic (450ºC) pyrolysis (catalyst/waste plastic = 0.4 g/g).
The second half of the project will be dedicated to the final upgrading of the oil obtained from the catalytic pyrolysis using a hydrodehalogenation process with new developed catalysts as well as the safe disposal of the removed halogens in the gas and solid phases produced in the whole thermochemical process.