Carbon dioxide reforming of methane over La2NiO4 as catalyst precursor—Characterization of carbon deposition

La2NiO4-type perovskites were prepared by the “self-combustion” method and were used as catalyst precursor for the CO2 reforming of CH4 reaction at 700 °C. The catalysts were used in reduced and non-reduced form. High CH4 and CO2 conversions were obtained with a H2/CO ratio lower than 1. This result was explained by the occurrence of the RWGS (reverse water gas shift) reaction. The reduction of the perovskite La2NiO4 leads to the formation of small nickel particles (average diameter: 7 nm), consequently the catalytic activity is higher than that obtained with 5% Ni/La2O3 (average diameter: 11 nm). The use of the perovskite La2NiO4 without reductive treatment prior to the reaction shows that the catalyst is composed of a mixture of Ni, La2O2CO3 and La2NiO4 during the first hours of the reaction. The catalytic activity is thus lower than that obtained with the reduced perovskite. The reaction performed using the non-reduced perovskite is accompanied by carbon deposition. TEM and Raman analysis showed that multiwalled carbon nanotubes are formed under those experimental conditions.