The in situ autocombustion synthesis route is shown to be an easy and efficient way to produce nanoscaled nickel oxide containing lanthanum-doped mesoporous silica composite. Through this approach, ~3 nm NiO particles homogeneously dispersed in the pores of silica are obtained, while lanthanum is observed to cover the surface of the silica pore wall. Subsequent reduction of such composite precursors under hydrogen generates Ni(0) nanoparticles of a comparable size. Control over the size and size distribution of metallic nanoparticles clearly improved catalytic activity in the methane dry reforming reaction. In addition, these composite materials exhibit excellent stability under severe reaction conditions. This was achieved through the presence of LaOx species, which reduced active-site carbon poisoning, and the confinement effect of the mesoporous support, which reduced metallic particle sintering.

Ca 1-x La x NiAl 11 O 19-d (O B xB1) hexaaluminate oxydes were synthesized starting from nitrate salts of Ca, La, Ni and Al precipitated by citric acid. After calcination they were used as catalysts precursors in dry reforming of methane to synthesis gas at atmospheric pressure (600-800°C) with a mixture of CH 4 /CO 2 /Ar:1/1/3. The solids were characterized by X-ray diffraction (XRD), BET surface area, temperature programmed reaction and oxidation (TPO) and by X-ray photoelectron spectroscopy. XRD analysis shows a pure hexaluminate phase as soon as a part of calcium has been substituted by lanthanum. After H 2 reduction and after reactivity test, Ni metal characterized by XRD is responsible of the high activity (equilibrium conversion near 100% at 800°C). Ni hexaaluminate shows a remarkable high stability (more than 300 h test) probably due to the low formation of surface carbon (TPO).