Dopant-driven tuning of toluene oxidation and sulfur resistance at the B-site of LaCo1−xMxO3 (M = Fe, Cr, Cu) perovskites

Abstract

The objective of this work was to investigate and contrast the mechanism of different B-site dopants for catalytic activity and sulfur resistance under equivalent conditions. LaCo_1−xM_xO₃ (M = Fe, Cr, Cu) perovskite-type catalysts were synthesized by a sol–gel method, and the optimized samples were tested for toluene oxidation before and after sulfur aging. The properties of the catalysts were investigated in detail by XRD, FT-IR, N₂ adsorption–desorption, H₂-TPR, XPS and in situ DRIFTS to elucidate the inner mechanisms of the catalytic reaction and poisoning processes. The results indicated that introducing specific metal cations with a suitable ratio into the B-site of perovskite could improve the catalytic activity and weaken the negative effect of SO₂ poisoning. The reasons for the improvement of catalytic activity on different doped catalysts are similar and mainly lie in the change of reduction property, oxidation state of the B-site, and content of oxygen vacancies. However, the mechanism of sulfur resistance caused by different dopants is not identical. The introduction of different metal cations will cause certain differences in some factors such as reducibility, lattice stability, sulfur adsorption and sulfate content, thus leading to the differentiation of sulfur tolerance for doped perovskite catalysts. In this study, the optimization effect of Fe dopant is better than that of Cr and Cu dopants, illustrating that the high stability of the perovskite lattice and the insensitivity to sulfur species are the key factors for its outstanding sulfur resistance. The results provide insights into guiding the practical composition and life cycle optimization of perovskite-type catalysts in the industrial application of removing sulfur-containing VOCs.