Stabilization of low nickel content catalysts with lanthanum and by citric acid assisted preparation to suppress deactivation in dry reforming of methane

Methane dry reforming (DRM) was studied over Ni catalysts with low active metal content (2.5 wt%) supported on MgO-Al2O3. The aim was to develop catalysts that are stable against different deactivation effects and achieve outstanding DRM reactivity at severe conditions. The solids were characterized using N-2 physisorption, X-ray diffraction, temperature-programmed reduction, UV-vis diffuse reflectance spectroscopy, and scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy. The results show that the low Ni content catalysts may not only suffer from rapid carbon deposition and particle growth but also Ni re-oxidation. La addition and citric acid complexation during the Ni catalyst preparation not only stabilizes Ni dispersion but also limits the Ni re-oxidation as well as the coking rate during the reaction. The most effective Ni catalyst shows high and stable DRM reactivity over 160 h with an exceptionally high productivity of syngas. Furthermore, catalysts of such type were evaluated in DRM with CH4-rich feed to mimic the direct conversion of some biogases or specific natural gases. Even at such harsh conditions the spent catalysts exposed remarkably low carbon deposition. Those results are promising for Ni catalyst development for industrial scale DRM.