Synergetic Effect of K Sites and Pt Nanoclusters in an Ordered Hierarchical Porous Pt-KMnO_x/Ce_0.25Zr_0.75O₂ Catalyst for Boosting Soot Oxidation

Abstract

We have designed and elaborately fabricated the ordered hierarchical macro-meso-microporous catalysts of Ce0.25Zr0.75O2-supported Pt-embedded KMnO x nanoparticles (OMMM Pt-KMnO x /Ce0.25Zr0.75O2). Three dimensionally ordered macro-mesoporous (3DOMM) Ce0.25Zr0.75O2 oxide was synthesized by the combined methods of evaporation-induced interfacial self-assembly (EISA) and colloidal crystal templates (CCT). KMnO x nanoparticles (NPs) possess the natural microporous nanostructure of an octahedral molecular sieve (OMS) with an average size of 0.46 nm. Pt nanoclusters were anchored in situ at the microporous structure of KMnO x NPs and formed Pt-KMnO x active sites. For the OMMM Pt-KMnO x /Ce0.25Zr0.75O2 catalyst, a 3D ordered macroporous (250 nm) structure can enhance contact efficiency between soot and catalysts, and a high specific surface area with contributions from ordered mesopores (5 nm) is beneficial for dispersion of KMnO x NPs and activation of gaseous reactants (O2 and NO). Meanwhile, a microporous (0.46 nm) structure can anchor K sites and ultrafine Pt nanoclusters. The synergetic effect of ternary K-Mn-Pt components can transform gas reactants to the effective intermediate species and thereafter oxidize the well-dispersed soot particles. The OMMM Pt-KMnO x /Ce0.25Zr0.75O2 catalyst possesses high catalytic activity and stability for soot oxidation under the conditions of loose contact: i.e., its TOF value is 2.10 h–1 at 290 °C, which is more than a 4-fold increase over the 3DOMM Ce0.25Zr0.75O2 support (0.47 h–1). The architected hierarchical porous structure rationalizes an alternative protocol to improve solid–solid contact and the resulting activity, which can be further applied to other catalysis systems with different catalysts and reactants.

Metal–Support Interactions on Ag/Co3O4 Nanowire Monolithic Catalysts Promoting Catalytic Soot Combustion

“…In addition, soot is a type of particulate with a diameter of 25-100 nm, which makes touching the inner surface of mesopores and micropores in traditional powder catalysts difficult during a reaction, resulting in low soot-catalyst contact efficiency and unsatisfactory catalytic performance [29]. To solve this problem, Zhao's research group [12,30,31] developed a series of three-dimensional ordered macroporous catalysts using the colloidal crystal template method for catalytic soot elimination, which can greatly improve the contact efficiency and catalytic soot oxidation performance. Zhang's group [32,33] focused on multiple strategies to decrease the ignition temperature of soot combustion.…”

Promotion of A-Site Ag-Doped Perovskites for the Catalytic Oxidation of Soot: Synergistic Catalytic Effect of Dual Active Sites

“…We speculate that there were at least two types of active sites on the surface of the LA 2.5 C catalyst, including Co 3+ and oxygen vacancies . NO oxidation on LA 2.5 C mainly follows the MVK mechanism, which promotes the oxidation of soot …”

“…26 NO oxidation on LA 2.5 C mainly follows the MVK mechanism, which promotes the oxidation of soot. 51 3.3. DFT Results.…”

Facilitating Catalytic Purification of Auto-Exhaust Carbon Particles via the Fe2O3{113} Facet-dependent Effect in Pt/Fe2O3 Catalysts

“…The carbon particulate matter (mainly soot particles) with adsorbed toxicants derived from vehicle exhaust is an important source of urban atmospheric fine particles, which can seriously endanger physical health and environment. − In the after-treatment system of vehicle exhaust, the particulate filter combined with the catalysts is widely regarded as one of the most efficient methods to eliminate them, and the catalysts are crucial to the removal efficiency of soot particles. − In recent years, a great number of high-efficient catalysts reported by the scientists are able to achieve catalytic soot purification at low temperatures, whose compositions involve noble metals, − transition-metal oxides, − alkaline metal oxides, , perovskite-like type oxides, − and rare earth oxides. − The primary active component in the commercial catalysts for soot purification is noble metal (Pt and Pd) elements, and the usage amount of the Pt element in the field of automobile exhaust purification exceeds 30% of the total usage amount in the Pgm market report (May 2021) of Johnson Matthey. Thus, the key issue is to decrease the usage amount of the Pt element in the catalysts for vehicle exhaust purification. , However, the role and mechanism of the Pt element and metal oxide support in improving the removal efficiency of soot particles are still unclear, and it is still a challenge to obtain high-efficient Pt-based catalysts for the removal of soot particles.…”