Insight into the effect of catalytic reactions on correlations of soot oxidation activity and microspatial structures

A catalyst is usually coated on Diesel particulate filter (DPF) for assisted regeneration. In this paper, the oxidation activity and pore structure evolutions of soot under the effect of CeO₂ are explored. CeO₂ effectively increases the oxidation activity of soot and reduces the initial activation energy; in the meantime, the addition of CeO₂ changes the soot oxidation mode. Pure soot particles tend to produce the porous structure in the oxidation process. Mesopores promote the diffusion of oxygen, and macropores contribute to reduce the agglomeration of soot particles. Additionally, CeO₂ provides the active oxygen for soot oxidation and promotes the multi-point oxidation at the beginning of soot oxidation. With the oxidation proceeding, catalysis causes the collapsion of soot microspatial structures, in the meantime, the macropores caused by the catalytic oxidation are filled by CeO₂. It results in the tight contact between soot and catalyst, further promoting the formation of the available active oxygen for soot oxidation. This paper is meaningful to analyze the oxidation mechanism of soot under catalysis, which lays a foundation for improving the regeneration efficiency of DPF and reducing the particle emission.

Potassium promoted macro-mesoporous Co3O4-La0.88Sr0.12CoO3-δ nanotubes with large surface area: A high-performance catalyst for soot removal

The construction of porous perovskite nanotubular materials with a good intrinsic activity, as well as a greater dispersion of the active sites is an effective strategy to obtain a high-performance catalyst used in soot removal. Thence, macro-mesoporous Co₃O₄-La_0.88Sr_0.12CoO_3-δ nanotubes with large specific surface area (154.4 m²·g^-1) from the acid etching of the porous La_0.6Sr_0.4CoO_3-δ nanotubes, are supported by 5% K through bubbling method following calcination for soot combustion. The relationship between the specific surface area and K dispersion and their effect on the activity are studied by a series of isothermal kinetic measurements combined with the characterizations and activity evaluation results. It can be found that the greater the amount is of K⁺ incorporated into perovskite lattice, the better the dispersion of K, as well as the La₂O₂CO₃ formed on the catalyst surface, thus leading to the enhanced performance in the soot catalytic combustion. As a result, the 5% K supported macro-mesoporous Co₃O₄-La_0.88Sr_0.12CoO_3-δ nanotubes after acid etching show good activity and stability, where the T₅₀ is 338 °C (5% O₂ + 500 ppm NO + 6% H₂O) with a good CO₂ selectivity (above 99%), the activate energy is 78.1 kJ·mol^-1, and the turnover frequency is 5.14 × 10^-4 s^-1.

Three-dimensionally ordered macroporous K0.5MnCeOx/SiO2 catalysts: facile preparation and worthwhile catalytic performances for soot combustion

A series of novel catalysts with three-dimensionally ordered macroporous structures and active-component nanoparticles, exhibiting excellent catalytic performance for soot combustion, were fabricated.

Construction of a hollow structure in La0.9K0.1CoO3−δ nanofibers via grain size control by Sr substitution with an enhanced catalytic performance for soot removal

The hollow structure is formed by Sr²⁺ doping in La_0.9K_0.1CoO_3−δ nanofibers for decreasing the grain size, which can improve the contact efficiency of soot–catalyst–gas as well as the intrinsic activity, responsible for the enhancement in activity.

PrOx catalysts for the combustion of soot generated in diesel engines: effect of CuO and 3DOM structures

PrO_x and CuO/PrO_x catalysts have been prepared with conventional (Ref) and three dimensionally ordered macroporous (3DOM) structures, and the effect of the structure on soot combustion has been studied.

Self-templating construction of mesopores on three-dimensionally ordered macroporous La0.5Sr0.5MnO3 perovskite with enhanced performance for soot combustion

A three-dimensionally ordered macroporous (3DOM) La_0.5Sr_0.5MnO₃ perovskite was prepared by a colloidal crystal templating method, with extra mesopores created by selective dissolution method performed successively.

Synthesis and applications of nanoporous perovskite metal oxides

Perovskite-type metal oxides have been widely investigated and applied in various fields in the past several decades due to their extraordinary variability of compositions and structures with targeted physical and chemical properties (e.g., redox behaviour, oxygen mobility, electronic and ionic conductivity). Recently, nanoporous perovskite metal oxides have attracted extensive attention because of their special morphology and properties, as well as superior performance. This minireview aims at summarizing and reviewing the different synthesis methods of nanoporous perovskite metal oxides and their various applications comprehensively. The correlations between the nanoporous structures and the specific performance of perovskite oxides are summarized and highlighted. The future research directions of nanoporous perovskite metal oxides are also prospected.

Carboxyl-modified colloidal crystal templates for the synthesis of three-dimensionally ordered macroporous SMMN2O5 mullite and its application in NOx-assisted soot combustion

Schematic illustration of NO_x-assisted soot combustion.

Facile synthesis of three-dimensional ordered macroporous Sr1−xKxTiO3 perovskites with enhanced catalytic activity for soot combustion

The appropriate incorporation of potassium into 3DOM SrTiO₃ perovskites effectively improved the catalytic performance for soot combustion.