Facile synthesis of catalytically active CeO₂ for soot combustion

Abstract

Pure ceria catalysts were prepared by a facile modified homogeneous co-precipitation method, and their catalytic performance was evaluated in the soot oxidation reaction. The structure and textural properties of the synthesized catalysts were characterized via XRD, N 2 adsorption/desorption, TG-DSC-MS, H 2 -TPR, FE-SEM, HR-TEM and XPS techniques. It is shown that CeO 2 samples prepared by the improved co-precipitation method exhibit obviously better catalytic activity than those prepared by the conventional co-precipitation method. The CeO 2 -CP4-F sample shows the best activity, for which the peak temperature, T p , values of soot combustion are about 465°C in O 2 stream gas and 430°C in a NO/O 2 stream under soot/catalyst "loose contact" conditions. Moreover, after high temperature aging, the activity of CeO 2 -CP4-A becomes even better, for which the T p value of soot combustion is lowered to 445°C in O 2 air gas. The catalytic activity is not well associated with the physicochemical properties of BET surface area, particle size and reducibility at low temperatures. The number of lattice oxygen and its mobility in the series of CeO 2 may be the crucial factor to decide the overall catalytic performance. According to the HRTEM result, the excellent migration of lattice oxygen may result from the preferential exposure of more-reactive planes, which may be the essential reason to explain the good performance of CeO 2 catalysts in soot oxidation.

Synthesis and application of rare-earth elements (Gd, Sm, and Nd) doped ceria-based solid solutions for methyl mercaptan catalytic decomposition

“…The presence of all these peaks clearly indicate the coexistence of Ce 4+ and Ce 3+ ions on the surface of all samples. More importantly, it is reported that the existence of Ce 3+ in doped ceria based catalysts is generally associated with the formation of oxygen vacancies, and higher concentration of Ce 3+ implies larger amounts of oxygen vacancies [31]. The relative Ce 3+ concentration can be determined by the ratio: Ce 3+ /(Ce 4+ + Ce 3+ ), where Ce 4+ and Ce 3+ represent the sums of the spectral peak areas related to the Ce 4+ and Ce 3+ , respectively [32].…”

Effect of Surface Copper Species on NO + CO Reaction over xCuO-Ce0.9Zr0.1O2 Catalysts: In Situ DRIFTS Studies

“…Here, three kinds of surface oxygen species were identified. The peak with binding energy at 531.1-531.3 eV can be attributed to the defect oxide or the surface oxygen ions with low coordination and weakly-bonded oxygen species (O ads ) adsorbed on oxygen vacancies, and the peak with binding energy at 532.3-532.7 eV is assigned to adsorbed oxygen species from hydroxyl and adsorbed water species (O w ) on the surface [38,40]. The peak with binding energy at 529.1-529.5 eV was ascribed to lattice oxygen (O latt ) [23].…”

Ag/CeO2 Composites for Catalytic Abatement of CO, Soot and VOCs

“…In Ref. [90] the catalytic activity of pure ceria prepared by co-precipitation method was described. Precipitation of aqueous solution of HNO 3 and Ce(NO 3 ) 3 was carried out using the 0.4 M NaOH solution and 0.4 M Na 2 CO 3 .…”