Catalytic H2O and CO2 reforming of CH4 over perovskite-based La0.8Sr0.2Cr0.9Ni0.1O3: Effects of pre-treatment and co-reactant/CH4 on its reforming characteristics Original Research Article

The H2O and CO2 reformings of CH4 over perovskite-based La0.8Sr0.2Cr0.9Ni0.1O3 prepared by precipitation, sol–gel and surfactant-assisted methods (calcined with air, nitrogen and hydrogen) were studied under solid oxide fuel cell (SOFC) conditions. It was found that the catalyst prepared by the surfactant-assisted method and calcined with hydrogen provided the highest specific surface area and reforming reactivity. Under typical conditions (H2O/CH4 and CO2/CH4 of 1.0), the reforming reactivity of La0.8Sr0.2Cr0.9Ni0.1O3 was comparable to that of Ni/Al2O3 but relatively less than that of precious-metal Rh/Al2O3. Nevertheless, at specific condition (H2O/CH4 and CO2/CH4 of 0.5–0.7), its activity dramatically increased to the same level as that of Rh/Al2O3.According to the study on the kinetic dependencies of La0.8Sr0.2Cr0.9Ni0.1O3, the reforming rate was proportional to CH4 partial pressure with the reaction order increased from 0.50 (at co-reactant/CH4 ratio of 1.0–3.0) to 0.95 (at co-reactant/CH4 ratio of 0.5). In addition, the rate was inhibited by H2 addition at high inlet co-reactant/CH4 ratio; however the inhibitory effect becomes less pronounced at an inlet co-reactant/CH4 ratio less than 0.7. It is suggested that one of two reforming mechanisms occurred depending on the operating conditions applied. La0.8Sr0.2Cr0.9Ni0.1O3 behaves like an oxide-based catalyst at high co-reactant/CH4 ratio, whereas it tends to behave more like a metallic-based catalyst at low co-reactant/CH4 ratios resulting in the high reforming reactivity. The study has shown that high surface area perovskite-based La0.8Sr0.2Cr0.9Ni0.1O3 catalyst has great potential to be applied as a steam reforming catalyst since it requires low inlet steam content, which provides significant benefits in terms of minimizing the water management in reformer and SOFC systems.