Looking inside a Ni-Fe/MgAl2O4 catalyst for methane dry reforming via Mössbauer spectroscopy and in situ QXAS

The evolution of the constituents an 8 wt%Ni-5 wt%Fe/MgAl2O4 catalyst for dry reforming methane (DRM) is monitored by in situ quick X-ray absorption spectroscopy (QXAS) and 57Fe Mössbauer spectroscopy. In as prepared state, Fe present NiFe2O4 at surface MgFe3+xAl2?xO4 within support, whereas Ni mainly NiO. During H2-TPR, NiO form alloy from 500 °C on partially reduced to MgFe2+xAl2?xO4, such that Ni-Fe alloy, MgFe2+xAl2?xO4 are prevalent phases catalyst. DRM, dominantly oxidizing environments (CH4/CO2 = 1/2, 1/1.5) lead formation FeOx nanoparticles thereby affecting DRM activity, possibly some reincorporation into support. For CH4/CO2 1/1, no significant changes occur catalyst’s activated a consequence reduction CH4 dissociation species counteracting oxidation CO2. However, analysis detects continued extraction sustaining ongoing alloying.