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CuO/CeO2 catalysts were widely studied as an alternative to precious metal catalysts, and the Cu–Ce synergy was essential to improve the catalytic performance. In this paper, the effects of CuO loading on Cu–Ce synergy in CuO/CeO2 nanorod catalysts and their performance in toluene combustion were systematically investigated. It was found that non-equilibrium plasma facilitated the dispersion of CuO active species on the CeO2 surface. With the increase of the CuO loading from 1 wt% to 4 wt%, the Cu–Ce synergistic effect was gradually improved, which generated Cu+/Cu2+ and Ce3+/Ce4+ redox electron pairs. The highest oxygen vacancy concentration and Cu+ content of CuCe-4 (4 wt%) resulting from strong Cu–Ce synergy accelerated the activation of chemisorbed oxygen and consequently improved the efficiency of toluene catalytic combustion. [ABSTRACT FROM AUTHOR]

Plasma catalysis is recognized as a promising technology for the elimination of diluted volatile organic compounds (VOCs). In this study, a hybrid process was carried out using dielectric barrier discharge (DBD) and MCeZr/TiO2 (M = Cu, Mn, Ni, and Co) catalysts for the degradation of VOCs. The plasma-catalytic system demonstrated a substantial improvement in toluene conversion and CO2 selectivity compared to the plasma-only system owing to the synergistic effects of plasma and thermal catalysis on toluene degradation. The performance of toluene removal follows the sequence of CuCeZr/T > NiCeZr/T > CoCeZr/T > MnCeZr/T in plasma catalysis. The CuCeZr/T catalyst demonstrated the highest toluene conversion of 99.0% and a CO2 selectivity of 91.0% at a discharge power of 30 W. Energetic electrons and reactive species generated by plasma actively participate in toluene activation in the gas phase and facilitate adsorption on the catalyst surface. The redox properties between Ce4+/Ce3+ and Cu+/Cu2+ species dictated the reducibility of the CuCeZr/T catalyst, promoting oxygen cycling during toluene oxidation and leading to enhanced catalytic performance. The pathways of toluene destruction in the plasma-catalysis system are discussed based on the analysis results of GC–MS, optical emission spectroscopy and calculations of the electron-impact reactions. [ABSTRACT FROM AUTHOR]

Glucose-free and glucose-containing LaCoO3(-G), La0.9Sr0.1CoO3(-G), and La0.9Ce0.1CoO3(-G) perovskite catalysts were synthesized via the sol–gel method, over which the oxidation performance of high-concentration CO was investigated. The experimental results indicate that the catalytic activity can be improved by facilely adding glucose during the preparation where glucose creates a reducing atmosphere and takes away the oxygen atoms of perovskites to form more oxygen vacancies and Co3+. CO self-sustained combustion is favorably achieved and La0.9Ce0.1CoO3-G shows the best catalytic performance. Combining the XPS, H2-TPR, O2-TPD and CO-TPD results, the outstanding performance of La0.9Ce0.1CoO3-G is mainly ascribed to the relatively higher concentrations of Co3+, Ce3+ and oxygen vacancies. The reaction was found to follow the Langmuir–Hinshelwood (L–H) mechanism by in situ IR spectroscopy and kinetic results. Furthermore, La0.9Ce0.1CoO3-G exhibits good high-temperature durability with unchanged CO conversion of 100% at 760 °C. It is suggested that the addition of glucose and the impregnation of Sr or Ce in perovskites is a feasible strategy to design industrial catalysts for CO self-sustained combustion. [ABSTRACT FROM AUTHOR]

Controlling the wetting property of ceramics, which is characterized by their water contact angles (WCAs), is of great interest because of their better thermal and chemical robustness compared with polymer materials. Among many ceramics, rare earth oxides (REOs) have attracted attention because of their high WCA ( 115°). Although several non-wetting mechanisms of REOs have been proposed thus far, the intrinsic mechanism has not been clarified yet due to the lack of information on crystallographic orientation-surface energy (SE)- WCA relationships. Here we report the WCA of (001), (110), and (111) oriented REOepitaxial films, which have different surface energies.We found that the WCA of fresh REO epitaxial film surfaces, which were prepared using a pulsed laser deposition technique, strongly depends on the crystallographic orientations, WCA(111) > WCA(111) > WCA(111), which reflects the differences in surface energy; SE(111) < SE(111) < SE(001). Moreover, we found that the WCA on REOs increases rapidly and converges to about 80° upon exposure to ambient air, regardless of the crystallographic orientation, likely due to surface adsorption of airborne carbon species. The present finding of 'There is a strong correlation between the crystallographic orientation,wetting property and the surface energy' is of great importance for the understanding of the wetting properties of ceramics. [ABSTRACT FROM AUTHOR]

The Pd/sulfoxide--phosphine-catalyzed highly enantioselective allylic etherification and amination with a wide range of O- and N-nucleophiles have been developed (up to 97% yield, 98.5% ee). The products can also be conveniently transformed into biologically active chiral heterocycles. [ABSTRACT FROM AUTHOR]