Kinetic modelling and measurement of catalyst deactivation for the catalytic co-pyrolysis of PP and PET with HZSM-5

The catalytic pyrolysis and co-pyrolysis of PP and PET with HZSM-5 zeolite catalyst was conducted for various catalyst to feedstock (CF) ratios, PP to PET ratios, and heating rates using a thermogravimetric analyzer (TGA). The Flynn-Wall-Ozawa (FWO) isoconversional approach was used to determine apparent activation energies for the non-catalytic and catalytic pyrolysis of PP and PET. An n^th-order reaction scheme was used to model the pyrolysis at various operating conditions through the optimization of the associated kinetic parameters. Additional TGA experiments were conducted with used catalysts to gain insight into catalyst deactivation, and it was found that the inclusion of PET led to more severe deactivation. Collidine temperature programmed desorption (TPD) indicated the loss of external acid sites for catalysts coked by PET pyrolysis, explaining the severe deactivation. Catalyst deactivation was incorporated into the kinetic modelling approach, so that degradation profiles could be predicted for experiments with the used catalysts.