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

Abstract

The perovskite-based materials are widely studied in heterogeneous catalysis; however, the low surface area seriously limits their practical application. Herein, this work proposes a strategy to prepare high surface area perovskite, by in-situ interfacial reaction between the 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 methane reforming 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 leads to decrease in specific surface area, the sample with La:Al of 1.0 still delivers high surface area of 32 m2/g. Such high surface area renders the catalysts high robustness towards variation in space velocity and feed gas composition. The Ni nanoparticles exsoluted from the perovskite matrix are much smaller and higher dispersion compared with the La-free sample, which contribute to the high capability towards CH4 and CO2 activation. The higher content of medium and strong basic sites substantially promotes the stability over 200 h. The samples with La:Al of 0.1 and 0.5 show only ~1% decreases in activity compared with 3% for La-free sample. The sample with La:Al of 0.1 shows the highest activity and stability, CH4 and CO2 conversion and H2/CO of 92.3%, 88.1% and 0.91, respectively, at 120,000 mL/(h·gcat). The strategy proposed in this work is believed to spur the study on the 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.