“…No diffraction peaks of any manganese oxides were detected, which may be because that the manganese has entered into the CeO 2 lattice and cerium manganese solid solution is formed, or because that the manganese oxides are highly dispersed on the surface of the cerium manganese solid solution and cannot be detected by XRD technique 23 – 25 . According to literature report 26 , the solubility of manganese in CeO 2 lattice in cerium manganese catalyst is smaller than 36%, so it can be inferred that most of the manganese species has entered into the CeO 2 lattice to form solid solution, with only a small proportion of manganese oxide dispersed on the surface of the cerium manganese solid solution. Figure 3 XRD patterns of cerium manganese catalysts: (1) CM-Na; (2) CM-NaC; (3) CM-NC; (4) CM-N; (5) CM-3.…”
Section: Resultsmentioning
confidence: 99%
“…It is well known that manganese oxides with high surface dispersion are difficult to be detected by XRD 23 – 25 . In our previous study 26 , we found that these surface manganese oxides could not only exhibit good reduction performance at low temperature, but also facilitate the contact between soot and catalyst. Therefore, if more surface manganese oxides can be provided, the catalytic combustion of soot is promoted.…”
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.
“…No diffraction peaks of any manganese oxides were detected, which may be because that the manganese has entered into the CeO 2 lattice and cerium manganese solid solution is formed, or because that the manganese oxides are highly dispersed on the surface of the cerium manganese solid solution and cannot be detected by XRD technique 23 – 25 . According to literature report 26 , the solubility of manganese in CeO 2 lattice in cerium manganese catalyst is smaller than 36%, so it can be inferred that most of the manganese species has entered into the CeO 2 lattice to form solid solution, with only a small proportion of manganese oxide dispersed on the surface of the cerium manganese solid solution. Figure 3 XRD patterns of cerium manganese catalysts: (1) CM-Na; (2) CM-NaC; (3) CM-NC; (4) CM-N; (5) CM-3.…”
Section: Resultsmentioning
confidence: 99%
“…It is well known that manganese oxides with high surface dispersion are difficult to be detected by XRD 23 – 25 . In our previous study 26 , we found that these surface manganese oxides could not only exhibit good reduction performance at low temperature, but also facilitate the contact between soot and catalyst. Therefore, if more surface manganese oxides can be provided, the catalytic combustion of soot is promoted.…”
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.
“…[11] CeÀ Mn oxide is a bimetallic catalyst considered a promising alternative for different reactions where catalytic oxidation is involved. Previous research indicates that this catalyst displayed excellent activity during the oxidation of soot, [12,13] formaldehyde, [14] and other air pollutants including NO X, CO, SO X , and toluene. [15] According to previous works, the catalytic activity of this bimetallic catalysts is affected by Ce concentration, support composition, active sites dispersion, shape, and size, among others.…”
Section: Introductionmentioning
confidence: 98%
“…Ce−Mn oxide is a bimetallic catalyst considered a promising alternative for different reactions where catalytic oxidation is involved. Previous research indicates that this catalyst displayed excellent activity during the oxidation of soot, [12,13] formaldehyde, [14] and other air pollutants including NO X, CO, SO X , and toluene. [ 15 ]…”
Volatile organic compounds (VOCs) are harmful to human health due to their carcinogenicity and toxicity. In addition, they are responsible for the generation of secondary atmospheric pollutants. Catalytic oxidation is an effective alternative for the reduction of these types of emissions. In this context, CeÀ Mn oxides have been reported as excellent catalyst because of their low cost, redox capacity, and oxygen mobility. To date, the best CeÀ Mn oxide catalysts have been produced using hydrothermal synthesis. In the present work, we propose a novel, facile, environmental-friendly, and low-cost sonochemical method for the synthesis of MnÀ Ce oxides with different Ce loadings. The new materials were characterized, and catalytic activity was measured in toluene oxidation reactions. Results demonstrated that, despite the low surface area of MnÀ Ce oxides prepared by sonochemical method, these samples showed a superior catalytic activity with T 90 values of 266 °C. This performance was the result of the higher Mn 4 + content, as well as improved reducibility and activation of O lat species as compared to that of hydrothermally synthesized catalysts. However, the interaction between Mn 2 O 3 and MnO 2 in the hydrothermally synthesized catalysts resulted in a greater stability in long-term oxidation reactions.
“…0.57Mn-CeO 2 catalyst has the highest Ce 3+ /(Ce 3+ + Ce 4+ ) ratio due to the appropriate amount of Mn doping. 23 The catalytic performance of 0.57Mn-CeO 2 may be related to the coexistence of Mn cation doped in different oxidation states of CeO 2 , and the catalyst containing the Mn 4+ cation with higher valence states is more suitable for the oxidation reaction. Multiple surface cation pairs of Ce 3+ , Ce 4+ , Mn 2+ , Mn 3+ , and Mn 4+ improve the electron transport inside the nanospheres, which is conducive to the production of reactive oxygen species for soot catalytic oxidation.…”
The aerosol pyrolysis method from nitrate precursors was used to prepare the Mn-CeO 2 catalyst containing Mn 2 O 3 , CeO 2 , and Mn-doped CeO 2 nanoparticles for catalyzing carbonous soot oxidation. The prepared Mn-CeO 2 catalysts have high specific surface areas, Ce 3+ ratio, and oxygen vacancy defects; these are a benefit for soot oxidation. The T 50 for soot oxidation on the 0.57Mn-CeO 2 catalyst is as low as 355 °C, which is 329 °C lower than that for soot oxidation without a catalyst. The catalysts were characterized using XRD, SEM-EDS, HRTEM, XPS, Raman spectroscopy, H 2 -TPR-MS, O 2 -TPD-MS, soot-TPR-MS, and operando DRIFTS-MS. The functions of Mn 2 O 3 , CeO 2 , and Mn-doped CeO 2 in the 0.57Mn-CeO 2 catalyst are unveiled. Mn-doped CeO 2 plays a key role and CeO 2 participates in soot oxidation, while Mn 2 O 3 is used to enhance higher ratios of Ce 3+ , via the reaction of Mn 3+ + Ce 4+ = Mn 4+ + Ce 3+ . The mechanism of soot oxidation on Mn-CeO 2 was proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
