Unveiling the catalytic behaviour of LaNiO3 and La2NiO4 for dry reforming of methane

Abstract

Comprehending the physicochemical characteristics of catalysts is essential for establishing the “structure-activity/property” correlations, making it crucial for catalyst advancement and the elucidation of reaction mechanisms. Here, we investigated combustion-synthesized perovskite LaNiO3 and layered perovskite La2NiO4, with mechanistic in situ FTIR studies for the first time in the context of sustainable syngas synthesis via dry reforming of methane. Time-on-stream experiments revealed that the as-synthesized LaNiO3 outperformed La2NiO4 initially, however, the used La2NiO4 exhibited improved catalytic activity with conversion of CH4 and CO2 to 63 and 82 %, respectively. Thermogravimetric analysis demonstrated insignificant coke formation over LaNiO3 with a rate of 1 × 10−3 mgc/gcat. h. Detailed compositional and species analysis unveiled the in-situ formation of metallic Ni0 during the reactions, which significantly influenced catalytic activity. H2-TPR studies indicated a higher reducibility of LaNiO3 with a total H2-uptake of 69.18 μ mol g−1 in contrast to 33.48 μ mol g−1 over La2NiO4. In situ FTIR and CO2-TPD studies revealed the higher basicity of LaNiO3 compared to La2NiO4, enhancing CO2 adsorption to a greater extent. This difference in reducibility, stemming from structural properties and availability of active basic sites, contributes to the distinct catalytic behaviours of both LaNiO3 and La2NiO4.