Stabilizing single-atom Ni on an Al2O3/N-C composite for efficient H2 production from polypropylene via pyrolysis-catalytic reforming

Converting plastic waste into hydrogen provides a promising route to simultaneously address environmental pollution and clean energy production. This study developed a Ni single-atom catalyst stabilized on an Al 2 O 3 /N-C composite support (Ni@Al 2 O 3 /N-C) for H 2 production from polypropylene (PP) via pyrolysis-catalytic reforming. The composite support integrates the high-temperature structural stability of Al 2 O 3 with the strong anchoring capability of N-doped carbon, enabling the formation of stable C-N-Ni active sites and effectively suppressing Ni aggregation under harsh reforming conditions. Under the optimal conditions (catalyst/PP = 1.25:1, water feed = 6 mL h −1 ), the catalyst achieved a gas yield of 127.59 mmol g −1 PP, a hydrogen yield of 84.14 mmol g −1 PP, and a hydrogen selectivity of 65.96%. The catalyst maintained good cyclic performance over 10 consecutive runs, with the H 2 yield decreasing from 84.14 to 69.39 mmol g −1 PP while the H 2 selectivity remained at 64.49% in the 10th cycle. XPS, HAADF-STEM, XRD, Raman, SEM, and TEM analyses confirmed that Ni remained atomically dispersed on the support after reaction, with no obvious nanoparticle agglomeration and only limited carbon nanotube formation. This work provides an effective support-engineering strategy for designing thermally stable single-atom catalysts for plastic reforming and other high-temperature catalytic processes.