Impact of oxygenated additive on polyethylene catalytic cracking over HY and HZSM-5 zeolite

The catalytic conversion of plastic waste is often complicated by additives. This study systematically investigates the influence of nonylphenol, a common oxygenated additive, on the catalytic performance of HY (FAU-type) and HZSM-5 (MFI-type) zeolites using high-density polyethylene (HDPE) and n -octane. The research revealed that nonylphenol exhibits a dual role: it provides an initial activity enhancement via bimolecular hydride transfer but more significantly acts as a potent coke precursor, driving rapid deactivation through pore-mouth blockage. Although nonylphenol accelerated deactivation, it did not alter the fundamental cracking pathway of n -octane on either zeolite. There are significant differences in deactivation behavior and selectivity trends between HDPE raw materials and n -octane model compounds. This discrepancy reveals the limitations of using n -octane as models to predict catalyst behavior in polyethylene catalytic cracking.