A Decrease in NiO‐MgO Phase Through Its Solid Solution Equilibrium with Tetragonal (La1−zSrz) 2Ni1−yMgyO4−δ: Effect on Catalytic Partial Oxidation of Methane

Abstract

Calcination of an oxide mixture consisting of 0.4 La2O3, 0.2 SrCO3, (1 − x)NiO, and xMgO at 800∘C results in an equilibrium between tetragonal phase and NiO‐MgO phase. Forming rock‐salt NiO‐MgO facilitates the NiO to join the tetragonal phase. The size of the NiO‐MgO phase in the resulting composite is reduced with the increase in MgO (the x value). The composite thus obtained is used to catalyze partial oxidation of methane, and the maximum methane conversion of ca. 93% is achieved when x = 0.2. A further rise in x value results in a monotonic decrease in the methane conversion. X‐ray diffraction, electron microscopy, and chemosorption all confirm a decrease in both size and amount of the supported Ni0 clusters with the increase in MgO dosage. The reduction in size promotes the dispersion of Ni0 sites and gives rise to both high activity and strong coking resistance.