Tuning aromatic selectivity in catalytic pyrolysis of epoxy resin over Nb/Ga-modified ZSM-5: porosity engineering and kinetic elucidation

For the high-value resource recovery of waste epoxy resin, this study prepared Nb and Ga modified ZSM-5 zeolite catalysts and systematically evaluated their performance in the catalytic pyrolysis of epoxy resin for aromatic hydrocarbon production. The results indicate that the bimetallic catalyst 8Nb4Ga (with 8% Nb and 4% Ga loading) exhibited the optimal catalytic activity, achieving the highest aromatic hydrocarbon yield of 68.6% under the conditions of 650 °C and a feedstock-to-catalyst mass ratio of 1:1. Characterization analyses confirmed that the metal species were well-dispersed on the ZSM-5 support without destroying the zeolite framework structure, though they induced changes in the pore structure. The introduction of Ga contributed to the formation of more mesoporous structures. Kinetic analysis revealed that the 8Nb4Ga catalyst significantly increased the apparent activation energy of the pyrolysis process, indicating that it guides the reactants through a higher-energy-barrier yet more selective pathway for aromatic hydrocarbon formation. This research provides theoretical support for the targeted catalytic conversion of waste epoxy resins into high-value aromatics. • Novel Nb-Ga/ZSM-5 bimetal catalyst for epoxy resin catalytic pyrolysis. • Aromatic hydrocarbons yield of 68.6% was achieved over catalyst 8Nb4Ga/ZSM-5. • Ga incorporation engineered the mesoporous structure, beneficial for mass transfer. • Kinetic studies elucidated a unique high-activation-energy pathway for selectivity. • Highly dispersed Nb/Ga species and intact zeolite framework were confirmed.