3DOM Mn-Based Perovskite Catalysts Modified by Potassium: Facile Synthesis and Excellent Catalytic Performance for Simultaneous Catalytic Elimination of Soot and NO_x 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 NO x . Nowadays, the design and preparation of catalysts with excellent catalytic activity for simultaneous removal of soot and NO x is a great challenge in the field of diesel exhaust abatement. In this work, a series of three-dimensional ordered macroporous (3DOM) La1–x K x MnO3 catalysts with high activity for the simultaneous elimination of soot and NO x 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 (T 10 = 336 °C, T 50 = 365 °C, and T 90 = 406 °C) and 50–60% NO conversion in the temperature range of 140–260 °C. Meanwhile, the reaction mechanism of 3DOM La1–x K x MnO3 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.

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

“…The peak at 529.2 eV was related to the lattice oxygen (O 2À ), whereas the peaks at 531.01 eV and 532.5 eV were correlated with the adsorbed oxygen (O À , O 2 À ). 38 In addition, the signal peak located at approximately 532 eV was assigned to NO 3 À in 15K/ LM-2h and 15K/LM samples, 33 which confirmed the presence of KNO 3 on both their surfaces. The adsorbed oxygen (O 2…”

“…This indicates the possibility of K ions replacing the La site of perovskite. 38 However, when the K loading exceeded 10%, the (110) diffraction peak moved to higher diffraction, which was related to the formation of new crystal phases. 39 In addition, the grain sizes of the catalysts were calculated by the Scherrer formula, and the values are displayed in Table 1.…”

Manganese Oxide-Based Catalysts for Soot Oxidation: A Review on the Recent Advances and Future Directions

“…Barium could effectively inhibit the sintering of oxide crystallites, which enabled the Ba/Mn−Ce (thermal aging) catalyst to maintain a high activity for NO oxidation and good thermal stability for soot oxidation (T 50 only slightly shifted from 405 to 429 °C after aging). Li et al 100 designed a series of 3DOM (La 1−x K x MnO 3 with x = 0, 0.05− 0.35) by a colloidal template technique for simultaneously oxidizing NO x and soot. In terms of catalytic activity, La 0.75 K 0.25 MnO 3 (3DOM) had high catalytic activity (90% soot conversion was achieved at 406 °C) due to the very high oxidization of B-site ions and the abundance of acid sites and active oxygen species, as well as the 3DOM structure.…”

Cadmium Sulfide 3D Photonic Crystal with Hierarchically Ordered Macropores for Highly Efficient Photocatalytic Hydrogen Generation

“…The three-dimensional ordered macroporous (3DOM) structure has been applied in various fields and confirmed to be promising in the direction of photocatalysis . The reasons why the 3DOM structure can develop fast are as follows: − The open interconnected hierarchical macroporous structure greatly enhances the efficiency of the species in transport and diffusion processes to the point of enhancing the photocatalytic ability. Then, the periodically ordered structure of 3DOM causes it to produce photon band gaps and slow photon effect of photonic crystals, which can effectively excite more photoinduced carriers and improve the photocatalytic activity.…”