Catalytic Degradation of Benzene over Nanocatalysts containing Cerium and Manganese

Abstract

A Ce–Mn composite oxide possessing a rod‐like morphology (with a fixed molar ratio of Ce/Mn=3:7) was synthesized through a hydrothermal method. Mn ions were doped into a CeO2 framework to replace Ce ions, thereby increasing the concentration of oxygen vacancies. The formation energies of O vacancies for the Ce–Mn composite oxide were calculated by applying density functional theory (DFT). The data showed that it was easier to form an O vacancy in the composite. The catalytic behavior of the Ce–Mn composite oxide for benzene degradation was researched in detail, which exhibited a higher activity than the pure phases. Based on this, the Ce–Mn composite oxide was chosen as a supporter to load PdO nanoparticles. The activity was enhanced further compared with that of the supporter alone (for the supporter, the reaction rate R 214 °C=0.68×10−4 mol gcat −1 s−1 and apparent activation energy E a=12.75 kJ mol−1; for the supporting catalyst, R 214 °C=1.46×10−4 mol gcat −1 s−1, E a=10.91 kJ mol−1). The corresponding catalytic mechanism was studied through in situ Raman and FTIR spectroscopy, which indicated that the process of benzene oxidation was related to different types of oxygen species existing at the surface of the catalysts.

Roles of Oxygen Vacancies of CeO2 and Mn-Doped CeO2 with the Same Morphology in Benzene Catalytic Oxidation

“…where E S_V O and E S are the total energies of the supercell with and without an oxygen vacancy, and E O 2 is the total energy of an O 2 molecule [49].…”

MnII/III and CeIII/IV Units Supported on an Octahedral Molecular Nanoparticle of CeO2

“…Mixed CeO 2 /MnO x materials make up an important class of heterogeneous catalysts because of their many applications in a wide range of industrial and environmental catalytic oxidation processes. Examples include oxidation of benzene , and other volatile organic compounds (VOCs) such as trichloroethylene, methyl tert -butyl ether, and chloroform and catalytic oxidation of CO, which is an important part of automobile exhaust emission control. , These oxides are also used in wastewater treatment via catalytic wet oxidation of dissolved organic pollutants such as chlorinated phenols and other chloro-organics, , ammonia, polyethylene glycol, , etc. They are often considered a useful alternative to noble metal catalysts, which suffer from limitations of high cost, low thermal stability, and catalyst poisoning.…”

Reactivity of Solid Rubrene with Potassium: Competition between Intercalation and Molecular Decomposition

“…KH-2-250 samples show only a very weak 1 H NMR signal for benzene compared to KH-2-210, suggesting a decomposition pathway in which benzene is not formed or the produced benzene was further degraded; it is reported that benzene can be decomposed even below 200 °C in the presence of metallic Ni or Ce 4+ /Mn 3+ ions. , Some impurity signals overlap with R 2– 1 H NMR signals inhibiting further NMR analysis (Figure S17a, SI). Apart from rubrene, the mass spectrum of KH-2-250 does show a species of mass 530.21(3) amu (Figure S18, SI), which is consistent with a dehydrogenated derivative of rubrene and is designated R* in Figure .…”