Catalytic co-pyrolysis of wet-torrefied bamboo sawdust and plastic over the zeolite HY: Synergism and kinetics

Abstract

In this study, the catalytic co-pyrolysis (CCP) of wet-torrefied bamboo sawdust (TB) and linear low-density polyethylene (LLDPE) over zeolites was carried out using the thermogravimetric analyzer. The analysis was carried out at four different heating rates (5–40 °C min−1) and under an inert (Ar) atmosphere. Four degradation stages were observed in the CCP of TB and LLDPE blends, the first stage being moisture removal. The peak decomposition temperature of catalytic pyrolysis (CP) of LLDPE over FAU was reduced by 251 °C as compared to that over HZSM-5 and the enhancement can be attributed to the topology of HY. The activation energies were calculated using isoconversional models: Kissinger–Akahira–Sunose model (KAS), Ozawa–Flynn–Wall model (OFW), and Friedman model (FM). The average activation energies (Eα) of the blends TBL3:1, TBL1:1, and TBL1:3 (TBL: Blend of torrefied biomass and LLDPE) were 171, 128, and 117 kJ mol−1, respectively, using the KAS model. The Eα of the blends was much lower as compared to that of TB, indicating a clear synergism. A multistep mechanism was observed in both CP of individual samples and CCP of blends, as analyzed by Criado's master plot. For example, the CCP of TBL1:3 followed geometric (volume) contraction (R3) and first-order reaction models at low and high conversions, respectively.