Surface acid etching for efficient anchoring of potassium on 3DOM La0.8Sr0.2MnO3 catalyst: An integration strategy for boosting soot and NOx simultaneous elimination

Highlights: • 3DOM La_0.8Sr_0.2MnO₃ perovskite was prepared by colloidal crystal templates method. • Citric acid treatment facilitated the dispersion of potassium. • Much more active oxygen species were generated after treated by citric acid. • The uniformly dispersed potassium could adsorb and anchor abundant NOx. • HKLSM showed high soot combustion activity and NOx to N₂ yield. The emission of soot and NOx is one of the most severe environmental issues, and the key factor is the development of catalysts in after-treatment systems. In this study, an innovative non-noble metal catalyst, named HKLSM, was fabricated by etching 3DOM La_0.8Sr_0.2MnO₃ with citric acid and synchronously anchoring potassium salt, for soot and NOx simultaneous removal. The citric acid could not only slightly erode the 3DOM skeleton, thereby beneficial to the dispersion of potassium, but also react with high-valence state Mn to generate abundant coordination unsaturated Mn³⁺ sites, which could produce more active oxygen species. Moreover, HKLSM showed a higher NOx adsorption capability than the samples that were not subjected to acid etching. This adsorbed NOx could be stored as NO₃⁻ species, which could facilitate soot combustion. Among all the as-prepared catalysts, HKLSM demonstrated a competitive soot combustion activity with a T₅₀ value of 368 °C, a TOF value of 3.24 × 10⁻⁴ s⁻¹, a reaction rate of 1.87 × 10⁻⁷ mol g⁻¹ s⁻¹, a total NOx to N₂ yield of 42.0% and favorable reusability and water-resistance. This integration strategy can rationalize an alternative protocol to soot and NOx simultaneous elimination or even other catalysis systems.