Design structure for CePr mixed oxide catalysts in soot combustion

Abstract

Four CePr mixed oxides with different structures were designed and synthesized using a solid-phase grinding method: a uniform solid solution of Ce and Pr (CePr-NN), Pr 6 O 11 -coated CeO 2 (CePr-NO), CeO 2 -coated Pr 6 O 11 (CePr-ON), and particle packing of CeO 2 and Pr 6 O 11 (CePr-OO) were obtained, and characterized by XRD, H 2 -TPR, TEM and TG. The results show that CePr-NN exhibits the best low temperature catalytic activity among the CePr catalysts. CeO 2 is the major active phase on the surface of the CePr catalysts, and the use of Pr 6 O 11 as the framework maintains the thermal stability of the CePr composite oxide. Moreover, both the oxygen storage capacity and mobility of the active oxygen of the catalyst were improved with the incorporation of Pr into CeO 2 , resulting in a higher combustion rate. The "molten state" which appeared during the preparation when nitrate was used as the precursor, plays a significant role in the migration of Ce and Pr, and is the premise of forming different structures of solid solution or coating structure.

Ce‐Pr Mixed Oxide Catalysts with a Fibrous Morphology for Low‐temperature PM Oxidation

“…This induced a sufficient and continuous supply of oxygen from the air to the reactant, which is crucial for catalytic activity. Furthermore, in contrast to the CeO 2 ‐NF sample, all the reduction peaks in the Ce X Pr 1−X O 2 ‐NF catalysts were within the range of the soot oxidation temperature (350–500 °C), which provides more available oxygen and thereby leads to a higher oxidation rate ,, . The TPR results confirmed that the incorporation of Pr into the ceria lattice (Ce X Pr 1−X O 2 ‐NF) improved the reducibility by oxygen and oxygen utilization in the samples.…”

“…The reduction of Ce X Pr 1−X O 2 ‐NF catalysts showed relatively large LT peaks and appeared at lower temperatures compared with the CeO 2 ‐NF sample. The increase in the LT peak area demonstrates improvement of the reducibility, which is useful for the oxidation reaction ,. In the soot oxidation reaction, reducibility at 300–500 °C is a significant factor, representing a well‐timed oxygen‐release capacity .…”

“…The increase in the LT peak area demonstrates improvement of the reducibility, which is useful for the oxidation reaction ,. In the soot oxidation reaction, reducibility at 300–500 °C is a significant factor, representing a well‐timed oxygen‐release capacity . From Figure , a quantitative comparison of the surface reducibility of samples was calculated by integrating the LT peak area based on the value of Ce 0.5 Pr 0.5 O 2 ‐NF; the data are presented in Table .…”

“…In the soot oxidation reaction, reducibility at 300–500 °C is a significant factor, representing a well‐timed oxygen‐release capacity . From Figure , a quantitative comparison of the surface reducibility of samples was calculated by integrating the LT peak area based on the value of Ce 0.5 Pr 0.5 O 2 ‐NF; the data are presented in Table . The Ce 0.5 Pr 0.5 O 2 ‐NF sample had the largest LT peak, which demonstrated the improvement of reducibility for the lower oxidation temperature, and the relative areas decreased in LT peaks as the contents of Pr in the ceria lattice decreased.…”

Improved Intrinsic Activity of Ce0.5Pr0.5O2 for Soot Combustion by Vacuum/Freeze-Drying

“…So far, coprecipitation (Katta et al, 2010;Kumar et al, 2012;Venkataswamy et al, 2014;Muroyama et al, 2015;Devaiah et al, 2016), hydrothermal (Nakagawa et al, 2015;Piumetti et al, 2015), sol-gel (Oliveira et al, 2012;Zhou et al, 2015;Alcalde-Santiago et al, 2019), microemulsion (Fan et al, 2017), and solid-phase grinding have been used to prepare CeO 2 -based oxides. However, the drying methods are scarcely discussed.…”