Plasma-enhanced steam reforming of different model tar compounds over Ni-based fusion catalysts

Highlights: • A hybrid DBD plasma-catalysis system is developed for reforming various model tars. • Ni/ZSM-5 shows higher performance than Ni/SiO₂ prepared by thermal fusion method. • Single-ring aromatic hydrocarbons and oxygenates exhibit higher reactivity than PAHs. • Performances of catalysis-alone, plasma-alone and in plasma-catalysis are compared. • Obvious synergy of plasma and catalyst is observed in plasma-catalysis system. -- Abstract: Tar formation during biomass gasification is undesirable due to the decreased energy efficiency and increased costs for maintaining downstream equipment. The hybrid non-thermal plasma-catalysis method is considered to be a promising alternative, since it overcomes the disadvantages arising from both catalyst deactivation during catalytic reforming and the formation of undesirable liquid by-products in plasma reforming. SiO₂- and ZSM-5-supported Ni-based catalysts with different Ni loadings (0.5, 1, 3, and 5 wt%) were prepared by thermal fusion and applied to the steam reforming of toluene. Different characterizations of fresh and spent catalysts including XRD, H₂-TPR, N₂ adsorption-desorption, SEM, TEM, XPS and TGA were conducted to show the properties of catalysts. The results indicated that Ni/ZSM-5 exhibited better performance than Ni/SiO₂, due to the increased dispersion of Ni particles and the stronger metal-support interaction of Ni/ZSM-5, which was confirmed by the TEM and H₂-TPR results. In addition, the performances of the catalysis-only (CatO), plasma-only (PlO), and in-plasma-catalysis (IPC) systems in steam reforming of different model tar compounds including benzene, toluene, furfural, naphthalene, fluorene and pyrene were compared using Ni(5 wt%)/ZSM-5. Obvious synergistic effects between DBD plasma and Ni(5 wt%)/ZSM-5 was observed for syngas production in the IPC system.