3DOM Mn-Based Perovskite Catalysts Modified by Potassium: Facile Synthesis and Excellent Catalytic Performance for Simultaneous Catalytic Elimination of Soot and NO_<i>x</i> from Diesel Engines

Abstract

Diesel engines have been widely applied, while the pollutants emitted from diesel engines have caused serious environmental pollution and human health hazards, especially for soot and NOx. Nowadays, the design and preparation of catalysts with excellent catalytic activity for simultaneous removal of soot and NOx is a great challenge in the field of diesel exhaust abatement. In this work, a series of three-dimensional ordered macroporous (3DOM) La1–xKxMnO3 catalysts with high activity for the simultaneous elimination of soot and NOx were synthesized by the colloidal crystal template method. The physicochemical properties of the as-prepared catalysts were characterized via XRD, Raman, FT-IR, SEM, TEM, N2 adsorption–desorption, XPS, H2-TPR, O2-TPD, NH3-TPD, NO-TPD, NO-TPO, and so on. The results of catalytic performance illustrated that 3DOM La0.75K0.25MnO3 exhibited highest catalytic activity with a maximum concentration of CO2 at 357 °C (T10 = 336 °C, T50 = 365 °C, and T90 = 406 °C) and 50–60% NO conversion in the temperature range of 140–260 °C. Meanwhile, the reaction mechanism of 3DOM La1–xKxMnO3 catalysts was also proposed based on the characterization results and DFT calculation. The reasons for high catalytic activity are related to the strong oxidizability of high-valence B-site ions, the abundance of active oxygen species and suitable acid sites, good reducibility, and the 3DOM structure.