Effect of oxygen vacancy and highly dispersed MnOx on soot combustion in cerium manganese catalyst

Abstract

Cerium manganese bimetallic catalysts have become the focus of current research because of their excellent catalytic performance for soot combustion. Two series of cerium manganese catalysts (Na-free catalysts and Na-containing catalysts) were prepared by coprecipitation method and characterized using XRD, N2 adsorption–desorption, SEM, Raman, XPS, H2-TPR, O2-TPD, Soot-TPR-MS and in situ IR. The effects of abundant oxygen vacancies and surface highly dispersed MnOx on soot catalytic combustion of cerium manganese catalysts prepared by different precipitants were analyzed. The activity test results show that the active oxygen species released by a large number of oxygen vacancies in the cerium manganese catalyst are more favorable to the soot catalytic combustion than MnOx which is highly dispersed on the surface of the catalyst and has good redox performance at low temperature. Because the catalytic effect of MnOx on the surface of Na-free catalysts is more dependent on the contact condition between the catalyst and the soot, this phenomenon can be observed more easily under the loose contact condition than under the tight contact condition. The activity cycle test results show that these two series of catalysts show good stability and repeated use will hardly cause any deactivation of the catalysts.

Dual-Emission Carbon Dots for Fluorescent Sensing of Permanganate

“…Conversely, the peak area increased such as the C–O/C–N at 285.8 eV and the O–CO at 288.4 eV of C 1s, and the C–O/C–O–C at 535.6 eV, strongly proving the enhancement of oxygen-containing groups by oxidation, including hydroxyl and carboxyl functional groups (Figure b,f,j) . The peak area of unsaturated pyridine-like N reduced from 18.6% to 8.7%, and the peak position shifted toward lower binding energy, possibly owing to the charge transfer and coordination interaction between the D-CDs and MnO 4 – (Figure c,g,k). ,, Satisfactorily, the oxidation state of Mn on the D-CD surface was estimated to be +2, as the distance between the twin peaks in the Mn 3s spectra (Δ E ) was approximately 5.8 or 5.9 eV (Figure h,l). , The reduction from Mn­(VII) to Mn­(II) further implies the oxidation reaction between the unsaturated groups and MnO 4 – .…”

“…32,39,40 Satisfactorily, the oxidation state of Mn on the D-CD surface was estimated to be +2, as the distance between the twin peaks in the Mn 3s spectra (ΔE) was approximately 5.8 or 5.9 eV (Figure 4h,l). 41,42 The reduction from Mn(VII) to Mn(II) further implies the oxidation reaction between the unsaturated groups and MnO 4…”

Cerium Doping Effect in 3DOM Perovskite-Type La2−xCexCoNiO6 Catalysts for Boosting Soot Oxidation

“…To date, researchers have effectively developed an array of diverse, highly efficient catalysts for deep catalytic soot oxidation at lower temperatures, encompassing noble metals [12][13][14][15], transition metal oxides [16][17][18][19], perovskite-type oxides [20][21][22][23][24], spinel-type oxides [25][26][27], rare-earth-based materials [28][29][30], and various other materials. Noble metal catalysts, characterized by their abundant unoccupied d-orbitals, demonstrate exceptional catalytic performance and have been commercially preferred for a long time [31,32].…”