Enhanced Gas/Oil Production from Catalytic Fast Pyrolysis of Polyethylene over Cu/Ce Co-Modified ZSM-5

This work aims to investigate the thermal behavior and kinetic characteristics of polyethylene (PE) pyrolysis over Cu/Ce modified ZSM-5. The influences of metal types, particles size of active center and interaction of Cu–Ce species on products distribution are elucidated.

Metal-modified ZSM-5 catalysts were prepared by negative pressure impregnation method. Catalytic fast pyrolysis and thermogravimetric experiments were conducted using Py–GC/MS and TG/MS for the qualitative and quantitative analysis of pyrolysis products.

Morphology characterization indicated the interaction of Cu–Ce species facilitated the regulation of active center size into a nanoparticle scale. The final products were restricted to a carbon number of less than 9 over CuCe/ZSM-5. Cu–Ce modification increased the aliphatic content from 58.5 to 76.1%. Kinetic analysis revealed a remarkable reduction in activation energies during both the intermediate and final stages, where an average decrease of 30% was achieved.

The synergistic effects of Cu⁰ and CeO_x facilitated the formation of more short chain olefins by enhancing C–C bonds cleavage activity. Undesired polycyclic aromatic hydrocarbons (PAHs) were avoided by the optimal steric hindrance of CuCe/ZSM-5.