Enhancement of soot oxidation activity of manganese oxide (Mn₂O₃) through doping by the formation of Mn_1.9M_0.1O_3–δ (M = Co, Cu, and Ni)

Abstract

The current work describes the catalytic soot oxidation activity of metal‐doped manganese oxide (Mn1.9M0.1O3–δ; M = Co, Cu, and Ni) materials, synthesized by coprecipitation method. All the fabricated materials were characterized using X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller surface area analysis, and X‐ray photoelectron spectroscopy (XPS). XRD analysis confirmed the formation of solid solution Mn1.9M0.1O3–δ (M = Co, Cu, and Ni). M‐doped samples exhibited different morphology when compared with pure Mn2O3 as evidenced by FESEM analysis, and Co‐doped Mn2O3 possessed the highest specific surface area. XPS analysis revealed the presence of multiple oxidation states of Mn (+4, +3, and +2) and Co (+2 and +3). Soot oxidation activity tests, performed using thermogravimetric analysis, showed that Mn1.9Co0.1O3–δ exhibited better catalytic performance (T50 = 390°C) when compared with pure Mn2O3 (T50 = 490°C). The incorporation of dopants greatly enhanced the oxygen vacancies and redox properties of Mn2O3.

Unveiling the Surface Chemical Reactions during Multi-Phase Catalytic Oxidation of Soot on Nanoengineering/Interfacing/Doping-Prepared Mn-CeO2 Catalysts Using TG-MS and Operando DRIFTS-MS

“…Figure B shows the Mn 2p XPS spectra, which are separated into three peaks locating at 643.6, 642.6, and 641.3 eV, which correspond to Mn 4+ , Mn 3+ , and Mn 2+ , respectively. ,, Mn 4+ /(Mn 2+ + Mn 3+ + Mn 4+ ) ratios are in the order of 0.249 (0.57Mn-CeO 2 ) > 0.230 (0.33Mn-CeO 2 ) > 0.222 (0.67Mn-CeO 2 ) > 0.219 (Mn 2 O 3 ). The higher Mn 4+ /(Mn 2+ + Mn 3+ + Mn 4+ ) ratio on the surface of the 0.57Mn-CeO 2 catalyst may indicate that more active sites are generated.…”

Manganese Oxide-Based Catalysts for Soot Oxidation: A Review on the Recent Advances and Future Directions

“…In particular, the codoping of Cu and Co into α-MnO 2 nanowires significantly improved the soot oxidation performance, having a value of T 50 (50% soot conversion) at 279 and 431 °C under the tested tight and loose contact conditions, respectively. Neelapala et al 89 investigated the catalytic soot oxidation activity of manganese oxide materials that contained doped metals (Mn 1.9 M* 0.1 O 3−δ , where M* = Co, Cu, and Ni). According to XRD spectra, M*doped specimens revealed different morphology structures than pure Mn 2 O 3 .…”

Enhanced Catalytic Soot Oxidation by Ce-Based MOF-Derived Ceria Nano-Bar with Promoted Oxygen Vacancy

“…Up to date, several transition metal oxides, including Ce, Co, Mn, Fe, Cu, V, and Mo [6][7][8][9][10][11][12][13][14][15], have been demonstrated as catalysts to decompose soot. Ce, especially CeO 2 , has become a particularly attractive catalyst for soot oxidation as CeO 2 exhibits a relatively high oxygen storage capacity via the redox cycle between Ce 4+ and Ce 3+ for reversibly adding/removing oxygen, making CeO 2 possess high catalytic activities [1,16].…”

“…Consequently, catalytic decomposition of soot has been regarded as a key step for eliminating soot [2][3][4][5], and catalysts for soot oxidation at lower temperatures and higher reaction rates are then highly crucial [2]. Up to date, several transition metal oxides, including Ce, Co, Mn, Fe, Cu, V, and Mo [6][7][8][9][10][11][12][13][14][15], have been demonstrated as catalysts to decompose soot. Ce, especially CeO2, has become a particularly attractive catalyst for soot oxidation as CeO2 exhibits a relatively high oxygen storage capacity via the redox cycle between Ce 4+ and Ce 3+ for reversibly adding/removing oxygen, making CeO2 possess high catalytic activities [1,16].…”