Chemical recycling of polytetrafluoroethylene by pyrolysis

Abstract

Production wastes of different polytetrafluoroethylene (PTFE) compounds (containing carbon black, glass fibers and bronze) were pyrolysed in a fluidized-bed reactor to gain fluorocarbons. The process parameters were varied to give high amounts of tetrafluoroethylene (TFE) and hexafluoropropene (HFP), which are important monomers for the production of fluoropolymers. At a pyrolysis temperature of 555 °C, yields of 76 wt% TFE, 7.1 wt% HFP and 5.2 wt% cyclo-perfluorobutane (c-C 4F 8) based on the PTFE input were obtained. At a temperature of 600 °C, the compounds containing carbon black and glass fiber showed a similar product distribution. For the bronze compound the yields of TFE, HFP and c-C 4F 8 were significantly reduced at the same temperature. The almost complete conversion of PTFE to gases by pyrolysis affords an excellent feedstock for a TFE production plant and can used to give monomers for the production of fluoropolymers.