Plasma-catalytic cracking of polyethylene over Ni/Hβ zeolites to light hydrocarbon fuels and hydrogen without external heating

The rapid accumulation of plastic waste poses severe environmental challenges. Cold plasma-driven degradation offers a promising route to convert plastic waste into high-value chemicals. In this study, a single-stage plasma reactor coupling cold plasma (dielectric barrier discharge) with Hβ zeolites was developed for polyethylene degradation under relatively mild conditions, without external thermal input or participation of noble metals. The effects of zeolite pore structure and acidity toward product distribution were investigated, revealing that Hβ-25 exhibited the highest C₁–C₆ yield (76 wt %) and a space-time yield of 103.8 mmol·g_cat⁻¹·h⁻¹ compared to other zeolite catalysts during the plasma-catalytic process. Meanwhile, it was revealed that efficient pre-cracking initiated by plasma activation and the optimal structural compatibility between Hβ-zeolite pore channels and primary cracking products were the key factors enabling the selective conversion of polyethylene into C₁–C₆ hydrocarbons. Additionally, metal incorporation significantly enhanced C–H bond cleavage compared to Hβ-25 support. Especially, 10Ni/Hβ-25 exhibited the highest hydrogen yield (7.87 mmol·g_plastic⁻¹) under plasma-assisted mode, markedly surpassing its yield under thermal-cracking conditions, demonstrating the significant potential of plasma-catalytic degradation for hydrogen production from polyethylene.