Construction of high surface area perovskite-based catalysts by in situ interfacial reactions: Ni-doped LaAlO3 for dry reforming of methane as a case study

Abstract

Perovskite-based materials are widely studied in heterogeneous catalysis; however, their low surface area seriously limits their practical applications. Herein, this work proposes a strategy to prepare high surface area perovskites via in situ interfacial reactions between loaded metal ions and the support. Specifically, lanthanum and nickel ions are sequentially loaded onto the commercial alumina support to prepare Al₂O₃-supported Ni-doped LaAlO₃ for dry reforming of methane as a case study. The properties of the resultant Ni-doped LaAlO₃ strongly depend on the ratio of La to Al. Increasing La : Al from 0.1 to 1.0 led to a decrease in the specific surface area, but the sample with an La : Al ratio of 1.0 still delivered a high surface area of 32 m² g⁻¹. Such a high surface area rendered the catalyst with high robustness towards variation in space velocity and feed gas composition. The Ni nanoparticles exsoluted from the perovskite matrix are much smaller and displayed a higher dispersion compared with the La-free sample, contributing to a high capability towards CH₄ and CO₂ activation. The samples with La : Al ratios of 0.1 and 0.5 show only a ∼1% decrease in activity compared with a 3% decrease in the La-free sample. The sample with an La : Al ratio of 0.1 shows the highest activity and stability, CH₄ and CO₂ conversion and H₂/CO ratio of 92.3%, 88.1% and 0.91, respectively, at 800 °C and 120 000 mL (h⁻¹ g_cat⁻¹). The strategy proposed in this work is believed to spur the study on perovskite-based catalysts and thus promote their practical application. Furthermore, the strategy can be extended to prepare other types of complex catalysts, such as spinel and pyrochlore, of high surface area.