Catalytic Oxidation of Soot on a Novel Active Ca-Co Dually-Doped Lanthanum Tin Pyrochlore Oxide

Abstract

A novel active Ca-Co dually-doping pyrochlore oxide La2−xCaxSn2−yCoyO7 catalyst was synthesized by the sol-gel method for catalytic oxidation of soot particulates. The microstructure, atomic valence, reduction, and adsorption performance were investigated by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), H2-TPR (temperature-programmed reduction), and in situ diffuse reflection infrared Fourier transformed (DRIFTS) techniques. Temperature programmed oxidation (TPO) tests were performed with the mixture of soot-catalyst under tight contact conditions to evaluate the catalytic activity for soot combustion. Synergetic effect between Ca and Co improved the structure and redox properties of the solids, increased the surface oxygen vacancies, and provided a suitable electropositivity for oxide, directly resulting in the decreased ignition temperature for catalyzed soot oxidation as low as 317 °C. The presence of NO in O2 further promoted soot oxidation over the catalysts with the ignition temperature decreased to about 300 °C. The DRIFTS results reveal that decomposition of less stable surface nitrites may account for NO2 formation in the ignition period of soot combustion, which thus participate in the auxiliary combustion process.

Monitoring intermediate species formation by DRIFT during the simultaneous removal of soot and NOx over LaAgMnO3 catalyst

“…Zhu et al [20], confirmed that bridged bidentate nitrites were the main adsorbed species over CeO2 and transition-doped ceria (M0.1Ce0.9O2) catalysts, since the bridged bidentate nitrates were scarcely observed. Ait et al [21], also evidenced the formation of chelating nitrites, bidentate and monodentate nitrates on La2Sn2-yCoy catalyst. Bin et al [15], on the other hand, presented information not only of the type of nitrates formed in the catalyst surfaces but also on the soot particle surfaces, as evidence of the interaction of the three components of the system (soot/O2/NOx).…”

High Performance of Mn-Doped MgAlOx Mixed Oxides for Low Temperature NOx Storage and Release

“…However, Mn15 catalyst showed a spherical shape nanoclusters structure. Small pores formed by the accumulation of elementary particles were observed on all oxides, which was in favor of the gaseous reaction in the catalytic process [38].…”

Studies on the structure, optical, ac conduction mechanism by OLPT model and impedance spectroscopy of La-doped Ba2SnO4 Ruddlesden Popper Oxide

“…It is noticed that with increasing the concentration of La at the Ba site above x=0.04, a weak XRD peak belongs to phase La2Sn2O7 is appeared in XRD pattern. However, the vibrational band associated with La2Sn2O7 is observed within the wavenumber range 550 to 680 cm -1 [37]. So, the identification of the pyrochlore phase present in the sample can't be done using this analysis.…”