CHEMICAL RECYCLING OF POLYTETRAFLUOROETHYLENE BY PYROLYSIS

Production wastes of different polytetrafluoroethylene (PTFE) compound s (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 hex afluoropropene (HFP), which are important monomers for the production of fluoropolymers. At a pyrolysis temperature of 555 degrees C, yields of 76 wt% TFE, 7.1wt% :HFP and 5.2 wt% cyclo-per-fluorobutane (c-C4F8 ) based on the PTFE input were obtained. At a temperature of 600 degre es C, the compounds containing carbon black and glass fiber showed a s imilar product distribution. For the bronze compound the yields of TFE , HFP and c-C4F8 were significantly reduced at the same temperature. T he almost complete conversion of PTFE to gases by pyrolysis affords an excellent feedstock for a TFE production plant and can used to give m onomers for the production of fluoropolymers. (C) 1998 Published by El sevier Science Limited. All rights reserved.