Sorry, old message that I'm just responding to now. PETE and many other plastics contain elemental oxygen. For PETE, that's about 1/3 oxygen. Oxygen plagues pyrolysis since it leads to the formation of acids, ketones and a number of other hard-to-remove contaminants.
You don't appear to understand or know that refineries handle feeds with oxygen. This is not a problem. They have not build a common pyrolysis machine.