Engineering surface-exposed LaCoO3 perovskite nanotubular catalysts for catalytic combustion of toluene through acid etching†

Resistance to SO₂ poisoning is a major technical challenge faced by catalysts in VOC oxidation. In this study, we prepared a series of nanotubular perovskite-based catalysts using electrostatic spinning technique. The catalytic activity of the prepared LaCoO₃ (LCO) catalyst could be significantly enhanced by doping with a small amount of Ce. Furthermore, acid treatment significantly enhanced the adsorption of VOC molecules on the catalyst surface, thus leading to the exposure of more Co³⁺ on the catalyst surface. Owing to the protective effects of CeO₂ and Co₃O₄, the acid etched Ce-doped LaCoO₃ catalyst exhibited outstanding catalytic performance towards toluene, even in the presence of water vapor and SO₂. The reason was that Ce addition increased the content of Co³⁺ and active oxygen species, and the acid treatment led to a further increase in the exposed Co³⁺ species on the catalyst surface. Meanwhile, Ce acted as a sacrificial site to protect Co³⁺ from being poisoned by SO₂. The synergistic effect of Ce doping and acid etching significantly improved the catalyst's resistance to SO₂. In situ FTIR confirmed that toluene primarily underwent a synergistic interaction of MvK and L–H mechanisms over the LCCO-2 catalyst. The possible reaction pathway is as follows: gaseous toluene → adsorbed toluene → benzyl alcohol → benzaldehyde → benzoate → anhydride → CO₂ and H₂O. Thus, this work provides innovative ideas for designing VOC catalytic combustion catalysts with excellent SO₂ resistance in the future.