Evaluation of HZSM-5 Zeolite as Cracking Catalyst for Upgrading the Vapours Generated in the Pyrolysis of an Epoxy-Carbon Fibre Waste Composite

Abstract

In this paper the performance of HZSM-5 zeolite in the thermo-catalytic treatment of the vapours and gases evolved from the pyrolysis of a carbon fibre-epoxy waste composite has been evaluated. The experiments have been carried out in a laboratory-scale installation consisting in a 3.5 L tank reactor, where pyrolysis of the waste happens, and a 0.5 m long tubular reactor placed in series, where the thermo-catalytic treatment of the gases and vapours coming from the tank reactor takes place. The catalytic activity of the zeolite has been studied at 700 and 900 °C, in two different placement configurations and in presence and absence of carrier gas. HZSM-5 zeolite is capable of cracking the organic compounds of the liquid phase, generating a liquid fraction with high proportion of water. In the presence of carrier gas, this catalyst also increases the proportion of H2 in gases. In general terms the effect of the catalyst is not very noteworthy, probably due to the large molecules that are involved in the process and due to problems of poisoning and deactivation with coke, sulphur and nitrogen compounds. In any case, it has been demonstrated that it is possible to produce a gas fraction with more than 50 vol.% of H2 in all experiments in which the treatment of gases and vapours is applied.