Dry-reforming of methane over bimetallic Ni–M/La2O3 (M = Co, Fe): The effect of the rate of La2O2CO3 formation and phase stability on the catalytic activity and stability

Abstract

Previous reports, albeit being partially contradictory, have indicated that the alloying of Ni with inexpensive transition metals, e.g. Co or Fe can affect the activity and stability of Ni-based catalysts under dry reforming conditions. In this work we critically assess the catalytic performance of Ni-based bi-metallic catalysts derived via the reduction of perovskite precursors, i.e. LaNi0.8M0.2O3 (M=Ni, Co and Fe). In-situ XRD and energy dispersive X-ray spectroscopy techniques were employed to probe metal–metal and metal–support interactions and phase transformations under reactive conditions. Ni–Co was found to be the most active catalyst, whereas Ni–Fe showed no activity. We observed that the addition of Co increases the rate of La2O2CO3 formation, which in turn enhances the removal of carbonaceous deposits from neighbouring active sites, thus, leading to a catalyst with an increased stability and activity. The poor activity of Ni–Fe was explained by the encapsulation of active Ni particle by LaFeO3.