Properties and phase composition of Ni–MgO–La2O3 systems submitted to different thermal treatments

Abstract

This work investigated the properties and phase composition of nickel-based systems supported on mixed oxides of lanthanum and magnesium (in different proportions) that were submitted to different thermal treatments. Catalysts were obtained by co-precipitation and were characterised using different techniques. The diffractograms of the nickel and lanthanum oxide catalysts show more intense peaks associated with a perovskite-type phase. The presence of magnesium leads to a decrease in the intensity of the peaks that correspond to the perovskite phase. The mixed system showed a higher specific surface area compared with that of the system formed by nickel and lanthanum oxides. The specific surface area of the mixed system was proportional to the magnesium content. The reduction profiles showed interactions in these systems. Metallic nickel is formed at temperatures greater than 873 K after reduction with hydrogen. The La2O2CO3 phase is formed under hydrogen-production reaction conditions. In conclusion, the systems formed by nickel, lanthanum and magnesium exhibit properties that render them suitable for application in hydrogen production reactions.