Effects of support on Ni-based catalysts for dry reforming of methane

Abstract

We report the development and evaluation of Ni-based catalysts supported on La₂O₃, ZrO₂, and Al₂O₃ for dry methane reformation. The catalysts were synthesized using the solution combustion synthesis (SCS) method, characterized using several cutting-edge analytical tools, and tested for CO₂ reformation of methane in a fixed bed plug-flow reactor. Catalytic activity and physicochemical properties of the studied catalysts varied considerably, indicating that the nature of support had a considerable impact. The Ni/Al₂O₃ nanocatalyst outperformed the Ni/La₂O₃ and Ni/ZrO₂ catalysts in terms of catalytic activity and stability during the DRM process. During T.O.S. stability tests, the Ni/La₂O₃ catalyst demonstrated higher initial CH₄ conversion (∼95.3 %) than the Ni/Al₂O₃ catalyst (∼88.7 %). However, after 50 h on stream, the Ni/La₂O₃ catalyst deactivated significantly, but the Ni/Al₂O₃ catalyst remained active. Amongst the catalysts tested, the zirconia-supported Ni catalyst had the least activity and demonstrated no activity at temperatures below 800 °C. The analysis of the TPR profile of the Ni/ZrO₂ catalyst demonstrated the presence of α-NiO species, indicating a weak metal to support contact, resulting in deactivation due to carbon deposition and aggregation of active sites. The thermogram of the Ni/La₂O₃ catalyst indicated a combination of two Ni species. The first reduction peak at 342.2 °C occurred by the reduction of α-NiO species. The second reduction peak at 695 °C was caused by the reduction of surface β-NiO species. The absence of δ-NiO species in the La₂O₃ crystals suggests that Ni²⁺ did not induce inside the lattice. In contrast, Ni/Al₂O₃ showed the presence of NiAl₂O₄ nanocrystallite (δ-NiO) spinel and NiO-Al₂O₃ solid solution, responsible for high activity and stability.