The role of Zr in modulating the electronic and structural properties of supported Ni catalysts for catalytic decomposition of methane

Catalytic decomposition of methane, which produces high-purity hydrogen and high-value-added carbon nanomaterials, has shown considerable potential for development and is expected to yield significant economic benefits in the future. However, designing catalysts that simultaneously exhibit high activity and long-term stability remains a significant challenge. Tuning the catalyst’s structure and electronic properties is an effective strategy for enhancing the reaction performance. In this work, a series of NixZr/ZSM-5 catalysts were prepared using the incipient wetness impregnation method, and the effect of Zr loadings on catalyst properties and performance was systematically investigated. The calcined and reduced catalysts were characterized by low-temperature N2 adsorption-desorption, XRD, SEM, H2-TPR and XPS. The results showed that the addition of Zr significantly increased the specific surface area of the catalyst and reduced the metal particle size. Smaller NiO particles were found to enter the pores of the HZSM-5 support, and electronic interactions between NiO and ZrO2 markedly enhanced the metal-support interaction. The catalyst exhibited optimal catalytic performance at a Zr loading of 5%, achieving a maximum methane conversion of 68% at 625 °C, maintaining activity for 900 min, and delivering a carbon yield of 1927%. Further increasing the Zr loading yielded only limited improvements in catalytic performance. Characterization of the spent catalysts and carbon products via TEM, Raman spectroscopy, and TGA revealed that the introduction of ZrO2 reduced metal sintering and promoted a shift in carbon nanofibers growth mode from tip-growth to base-growth. The mechanism of base-growth enabled the catalyst to maintain reaction activity for an extended period.