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A series of nanocrystalline copper–manganese oxides (denoted as Cu3−xMnx, x = 0, 1, 1.5, 2, 2.5, 3, where x means the molar ratio of Cu and Mn) were successfully prepared by a facile citric acid sol–gel method. The combination of Cu2+ and Mn3+ is intensified and enhanced interface effects generated, which is beneficial for the catalytic oxidation of benzene. A series of analyses, such as X-Ray Diffraction (XRD), N2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS), and hydrogen temperature programmed reduction (H2-TPR), were employed to further investigate the structural properties of the catalysts. An optimal Mn/Cu ratio of 2 forms CuMn2O4 spinels. CuMn2 with CuMn2O4 spinel structure presents a larger specific surface area, smaller pore diameter as well as more lattice oxygen species, exhibiting remarkable activity and stability for the catalytic oxidation of benzene. On account of these factors, CuMn2 possesses better low temperature reducibility and shows the best catalytic performance with 90% benzene conversion at 186 °C. The enhanced catalytic activity of CuMn2 is attributed to the stabilization of CuMn2O4 active phases and the intensive synergistic effect between Cu–Mn oxides. To prove the effect of CuMn2O4 spinel structure on catalytic performance, a CuO/Mn2O3 mixed catalyst (molar ratio 1 : 1) was prepared and applied to benzene oxidation (T90% = 198 °C), which indicates that the spinel structure has an encouraging effect on benzene catalysis. The catalytic properties of single copper oxide and manganese trioxide were also tested, the results show that CuMn2O4 has a crucial role in facilitating electronic transmission and mobility of the lattice oxygen. [ABSTRACT FROM AUTHOR]

Novel hierarchical ZnO hollow cubes are constructed using the interpenetrated 0D nanoparticles through directly decomposing the Zn-based metal–organic frameworks (Zn-MOF, ZIF-8). After decomposition at 450 °C for 1 h, the as-prepared ZnO well maintains the original ZIF-8 shape with relatively high surface area (45 m2 g−1), thereby realizing fast surface reaction kinetics of benzene molecules. In contrast to singular 0D ZnO nanoscale counterparts, the unique ZnO nanostructure assembly renders the well exposed surfaces and defect states, enhancing significantly chemical sensitivity towards gaseous benzene. The present work provides a facile and versatile approach for designing the high-performance chemical sensing materials. [ABSTRACT FROM AUTHOR]

CeO-MnO composites possessing rod-like morphology (fixed mole proportion of Ce/Mn) were synthesized through hydrothermal method and chosen as supporters to load PdO nanoparticles (PdO/CeMn). The size of loaded PdO nanoparticles is about 2 nm. The catalytic behaviors of supported catalysts were examined through the complete catalytic oxidation of benzene. The results illustrated that the activities of supported catalysts were enhanced greatly as compared to unsupported, and the completely conversion temperature of benzene was reduced to ca. 250 °C. The effect of noble metal species (PdO) addition on the catalytic property and crystal structure of composites was researched in detail. The data revealed that the interaction between PdO and supporter, and intrinsic properties of supporter resulted in the enhancement of catalytic abilities. [ABSTRACT FROM AUTHOR]

Porous ceramic membranes (PCMs) are considered as an efficient hot gas filtration material in industrial systems. Functionalization of the PCMs with high-efficiency catalysts for the abatement of volatile organic compounds (VOCs) during dust elimination is a promising way to purify the industrial exhaust gases. In this work, we prepared PCMs (porosity: 70%) in a facile sintering process and integrated Cu-doped Mn–Ce oxides into the PCMs as monolithic catalysts by the sol–gel method for benzene oxidation. Through this method, the catalysts are dispersed evenly throughout the PCMs with excellent adhesion, and the catalytic PCMs provided more active sites for the reactant gases during the catalytic reaction process compared to the powder catalysts. The physicochemical properties of PCMs and catalytic PCMs were characterized systematically, and the catalytic activities were measured in total oxidation of benzene. As a result, all the prepared catalytic PCMs exhibited high catalytic activity for benzene oxidation. Significantly, the monolithic catalyst of Cu0.2Mn0.6Ce0.2/PCMs obtained the lowest temperature for benzene conversion efficiency of 90% (T90) at 212 °C with a high gaseous hourly space velocity of 5000 h−1 and showed strong resistance to high humidity (90 vol.%, 20 °C) with long-term stability in continuous benzene stream, which is caused by abundant active adsorbed oxygen, more surficial oxygen vacancy, and lower-temperature reducibility. [ABSTRACT FROM AUTHOR]

Abstract: A series of CeO2–MnO x composite oxides were synthesized through hydrothermal method and the complete catalytic oxidation of benzene were examined. The effects of the Ceat/Mnat atomic ratio on the features of catalyst structure and catalytic behavior were researched. The results exhibited that the catalytic properties of CeO2–MnO x composite oxides were higher than pure CeO2 or MnO x . When the Ceat/Mnat ratio was 3:7, the catalytic activity reached the best. By means of testing, the data revealed that the synergistic effects existed in the composite oxides, which resulted in the enhancement of catalytic abilities. In the main phase, MnO x provided available oxygen species and CeO2 enhanced oxygen mobility. In addition, the nature of oxygen vacancy of catalysts was also studied through positron annihilation spectrum. The results showed that the concentration of oxygen vacancy for CeO2–MnO x composite oxides changed comparing with pure CeO2 or MnO x , which also caused the activity differences over benzene. [Copyright &y& Elsevier]