Effect of Fe and Mn Substitution in LaNiO₃ on Exsolution, Activity, and Stability for Methane Dry Reforming

• Main Authors: Eswaravara Prasadarao Komarala, Ilia Komissarov, Brian A. Rosen
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Catalysts
• Subjects: smart catalysts; regenerating catalysts; perovskites; solid-phase crystallization
• Online Access: https://www.mdpi.com/2073-4344/10/1/27

Perovskites LaNi_0.8Fe_0.2O₃ and LaNi_0.8Mn_0.2O₃ were synthesized using the co-precipitation method by substituting 20 mol.% of the Ni-site with Fe and Mn, respectively. Temperature programmed reduction (TPR) showed that the exsolution process in the Fe- and Mn-substituted perovskites followed a two-step and three-step reduction pathway, respectively. Once exsolved, the catalysts were found to be able to regenerate the original perovskite when exposed to an oxygen environment but with different crystallographic properties. The catalytic activity for both materials after exsolution was measured for the methane dry reforming (DRM) reaction at 650 °C and 800 °C. Catalyst resistance against nickel agglomeration, unwanted phase changes, and carbon accumulation during DRM were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The presence Fe alloying in the catalyst particles after exsolution from LaNi_0.8F_e0.2O₃ led to a lower methane conversion compared to the catalyst derived from LaNi_0.8Mn_0.2O₃ where no alloying occurred.