Nickel-doped La_0.2Sr_0.7Ti_1-xNi_xO_3-δ catalysts containing abundant oxygen vacancies as an optimized bifunctional catalyst for dry reforming of methane

The exsolution of metal nanoparticles from a perovskite oxide combined with concomitant oxygen vacancy creation can enhance the catalytic performance of the parent perovskite for the dry reforming of methane (DRM). Herein, a series of the Ni-substituted La_0.2Sr_0.7Ti_1-xNi_xO_3-δ (LSTN_x, x = 0.1, 0.2, 0.3, 0.4, 0.5) perovskite oxides were synthesized and comparatively characterized for their application in DRM. The multiphase oxide Ni–La₂NiO₄/LSTN_x was formed through the “doping-precipitation” strategy. The results showed that Ni nanoparticles and La₂NiO₄ nanoparticles were loaded on the surface of LSTN_x perovskite, accompanied by the generation of oxygen vacancies. Among them, Ni sites promoted the adsorption and dissociation of CH₄, while oxygen vacancies and La₂NiO₄ nanoparticles enhanced the activation of CO₂ and the migration ability of oxygen species. The synergistic effect of these three components achieved a balance in the activation of CH₄ and CO₂. The LSTN_0.4 catalyst maintained a stable CH₄ conversion of 82 % after time-on-stream experiments at 750 °C for 100 h. The reaction mechanism was further studied in combination with CH₄-TPSR and in-situ DRIFTS characterization.