Reduction of a Ni/Spinel Catalyst for Methane Reforming

A nickel/spinel (Ni/MgAl_2O_4) catalyst, w(Ni) = 22 wt %, was investigated in situ during reduction with wide-angle X-ray scattering (WAXS) in a laboratory setup and with anomalous small-angle X-ray scattering (ASAXS) at a synchrotron source. Complementary high-resolution transmission electron microscopy (HRTEM) was performed on the fresh catalyst sample. The Ni particles in the fresh catalyst sample were observed to exhibit a Ni/NiO core-shell structure. A decrease of the Ni lattice parameter is observed during the reduction in a temperature interval from 413 to 453 K, which can be related to the reduction of the NiO shell, whereby stress due to the lattice mismatch of Ni and NiO is relieved