Engineering surface Mn-enriched species and regulating active oxygen species over LaMnO3 catalysts by synergistic modification of acid etching and potassium support for soot removal

Abstract

Herein, a series of highly active K species-supported synergistically modified LaMnO₃ (LM) catalysts were prepared by acid etching for soot oxidation. As shown in XRD, TEM and XPS results, appropriate etching hours could remove La atoms on A-sites and produce A-site defects without destroying the whole perovskite structure, which created more B-sites on terminated perovskite surfaces and promoted the activation of oxygen molecules through Mn⁴⁺/Mn³⁺ redox cycles, thus improving the catalytic activity for soot combustion. Based on this, further modification of the LM catalyst by introducing K could enhance the lower temperature reducibility of the catalyst, and promote more active oxygen species production through the interaction between potassium and LM support, thereby leading to a further improvement in catalytic performance, as confirmed according to XPS O 1s and H₂-TPR results. Among all the as-prepared catalysts, the 15K/LM-2h catalyst exhibited favorable catalytic performance and stability, where the T₉₀ values were 416 °C and 327 °C under loose and tight contact, respectively, and the E_a value was 64.2 kJ mol⁻¹. This study provides a universal strategy for the development of high-performance catalysts for soot combustion with promising industrial application prospects.