CO2 dry-reforming of methane over La0.8Sr0.2Ni0.8M0.2O3 perovskite (M = Bi, Co, Cr, Cu, Fe): Roles of lattice oxygen on C–H activation and carbon suppression

La0.8Sr0.2Ni0.8M0.2O3 (LSNMO) (where M = Bi, Co, Cr, Cu and Fe) perovskite catalyst precursors have been successfully developed for CO2 dry-reforming of methane (DRM). Among all the catalysts, Cu-substituted Ni catalyst precursor showed the highest initial catalytic activity due to the highest amount of accessible Ni and the presence of mobile lattice oxygen species which can activate C–H bond, resulting in a significant improvement of catalytic activity even at the initial stage of reaction. However, these Ni particles can agglomerate to form bigger Ni particle size, thereby causing lower catalytic stability. As compared to Cu-substituted Ni catalyst, Fe-substituted Ni catalyst has low initial activity due to the lower reducibility of Ni–Fe and the less mobility of lattice oxygen species. However, Fe-substituted Ni catalyst showed the highest catalytic stability due to: (1) strong metal–support interaction which hinders thermal agglomeration of the Ni particles; and (2) the presence of the abundant lattice oxygen species which are not very active for C–H bond activation but active to react with CO2 to form La2O2CO3, hence minimizing carbon formation by reacting with surface carbon to form CO.