Pyrolysis is a process that heats plastic waste to high temperatures, typically 400 to 600 degrees Celsius, in the absence of oxygen. Instead of burning, the long polymer chains break apart into pyrolysis oil, gas and a solid residue called char.
It is the most widely used form of chemical recycling. The oil can be refined and used as feedstock for new plastic, with the recycled share allocated by mass balance, or it can be used as fuel. Only the first route counts as recycling; burning the oil is energy recovery. Pyrolysis can take mixed polyolefins and multilayer plastic that are hard to recycle mechanically, but it needs more energy, tolerates little PVC or PET, and yields less material than mechanical recycling.
