Ni/LaBO3 (B = Al, Cr, Fe) Catalysts for Steam Reforming of Methane (SRM): On the Interaction Between Ni and LaBO3 Perovskites with Differed Fine Structures

With the target to fabricate more feasible catalysts for SRM to produce hydrogen, the interaction between Ni and LaBO₃ (B = Al, Cr and Fe) perovskite supports with different B-sites has been explored. To avoid the formation of big Ni grains, the Ni loading is intentionally set as low as 2 wt%. XRD and Raman results revealed that the three LaBO₃ supports are composed of pure perovskite phase, but have differed fine crystal structures. While LaFeO₃ and LaCrO₃ can be indexed to the orthorhombic perovskite phase, LaAlO₃ can be indexed to the hexagonal phase. H₂-TPR and XPS results have validated that NiO has varied interfacial interactions with the LaBO₃ supports through partial electron transfer from the supports to Ni. As a consequence, the active metallic Ni surface areas are in the order of 2%Ni/LaAlO₃ > 2%Ni/LaCrO₃ > 2%Ni/LaFeO₃, well consistent with the reaction performance. Furthermore, by varying the B-site element, the abundance of the active surface oxygen species (mainly O₂²⁻) is varied, obeying the sequence of 2%Ni/LaCrO₃ > 2%Ni/LaAlO₃ > 2%Ni/LaFeO₃, well consistent with the anti-coking ability of the catalysts. It is discovered that the change of the fine crystal structure of LaBO₃ supports can influence the SRM performance of the 2%Ni/LaBO₃ catalysts evidently. The reaction performance of the catalysts is mainly determined by the active Ni surface area, but the anti-coking ability is majorly decided by the amount of active oxygen species.