Waste carpet recycling by selective pyrolysis

The disposal of the growing volume of mixed polymers in post-consumer waste presents a national challenge. Typical methods of disposal by landfilling and mass burning have some environmental concerns which necessitate the development of cost-effective recycling technologies and recovery of the maximum value from plastic wastes. Included in the plastic waste which currently ends up in landfills is nearly 3 billion pounds of carpet per year. The high value of the nylon-6, nylon-6/6, and polyester terephthalate (PET) face fiber material makes landfilling a very unattractive option as well, beyond the obvious environmental issues. However, the nature of the carpet construction, face fiber woven into a mixed polymer and inorganic backing material, makes typical recycling methods such as regrind and remelt impractical and uneconomical. To address this problem, NREL has been developing a process for the production of high-value chemicals from mixtures of waste plastics by using selective pyrolysis.