Elucidating the Support Effects of Perovskite Oxides for the Rational Design of Sinter-Resistant Catalysts

The rational design of thermally-stable heterogeneous catalysts is one of the most difficult and crucial parameters to control. The ability to develop a comprehensive strategy to decrease the occurrence of catalyst deactivation while maintaining the selectivity and activity is an important challenge. Sintering, or growth of the catalyst nanoparticle, is associated with a loss of surface area and activity. There are two processes that control the rate of sintering, either particle migration or Ostwald ripening. Particle migration usually occurs at lower temperatures while Ostwald ripening mechanism is relevant at higher temperatures. Strategies to mitigate sintering of catalyst nanoparticles should work to staunch either or both of these mechanisms. In this work, we report a strategy to limit particle migration and Ostwald ripening of Ni using so-called smart or perovskite oxide supports. The catalysts are synthesized in a manner that affixes or sockets nanoparticles to the surface of the perovskite support, in this case LaFeO₃. The socketing seems to constrain particle migration at low temperatures. Ostwald ripening effects still occur at elevated temperatures but is limited due to the strong interaction of the catalyst metal with the support. The methane dry reforming or CO oxidation activity and stability will be demonstrated. The materials were characterized using X-ray diffraction (XRD), H₂ pulse chemisorption, Scanning electron microscopy (SEM), Catalytic testing in a fixed-bed reactor, X-ray absorption spectroscopy (XAS) and Temperature-programmed surface reaction experiments (TPSR) and CO₂ temperature programmed desorption (TPD). This work contributes to the development of next generation supported catalysts that will go beyond the current limitations of predecessors and exhibit superior traits such as improved thermal stability and resistance to coking. The results of the perovskite oxide support shows promise for the rational design of economical catalysts (Ni and Fe) for DRM.