Reclamation of carbon fibers and added-value gases in a pyrolysis-based composites recycling process

Abstract Carbon fibers reclamation from waste composites by pyrolysis is developing fast. Pyrolysis allows the reclamation of the fibers by thermal decomposition of the polymeric resin, but the material value of these resins is not yet recovered. In this research work, the possibility of obtaining high-value gaseous fractions by treating the vapors generated in the decomposition of a poly(benzoxazine) containing carbon fiber waste composite has been studied. The experiments have been carried out in a lab-scale facility consisting of two reactors in series. In the first reactor, the pyrolysis of the waste is carried out at 500 °C, while in the second reactor the vapors coming from the first reactor are treated at 900 °C. Such treatment enables to triple the amount of gas in comparison to conventional pyrolysis. Besides, this gas contains 56% by volume of H2, which means the recovery of approximately 60% of the hydrogen contained in the resin. On the other hand, clean carbon fibers with mechanical properties within commercial values have been also obtained.