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In this work, plasma-catalytic oxidation of low concentration ethyl acetate (100 ppm) over La 1-x Ce x CoO 3+δ (x = 0, 0.05, 0.1, 0.3 and 0.5) perovskite catalysts was carried out in a coaxial dielectric barrier discharge (DBD) reactor. The effects of Ce-doping on the removal of ethyl acetate and CO x (x = 1 and 2) selectivity in the plasma-catalytic oxidation process were investigated as a function of specific energy density (SED). Compared to the plasma reaction without a catalyst, the presence of the LaCoO 3 catalyst in the plasma enhanced the removal of ethyl acetate and CO x selectivity. The use of the Ce-doped catalysts further enhanced the performance of the plasma-catalytic oxidation process. The highest removal efficiency of ethyl acetate (100%) and CO x selectivity (91.8%) were achieved in the plasma-catalytic oxidation of ethyl acetate over the La 0.9 Ce 0.1 CoO 3+δ catalyst at a SED of 558 J L −1 . The interactions between Ce and LaCoO 3 resulted in an increased specific surface area (by 17.1%–68.6%) and a reduced crystallite size (by 13.5%–68.2%) of the Ce-doped LaCoO 3 catalysts compared to pure LaCoO 3 , which favours the oxidation of ethyl acetate in the plasma process. Compared to the LaCoO 3 catalyst, the Ce-doped perovskite catalysts showed higher content (maximum 54.9%) of surface adsorbed oxygen (O ads ) and better reducibility, both of which significantly contributed to the enhanced oxidation of ethyl acetate and intermediates in the plasma-assisted surface reactions. The coupling of plasma with the Ce-doped catalysts also reduced the formation of by-products including NO 2 and N 2 O. The possible reaction pathways involved in the plasma oxidation process have been discussed. [ABSTRACT FROM AUTHOR]

A series of V-Ce(SO 4 ) 2 /Ti catalysts for selective catalytic reduction (SCR) of NO with ammonia are prepared by impregnation method. Low temperature SCR activity and alkali resistance of the optimal V-0.5Ce(SO 4 ) 2 /Ti sample are found to be better than on the commercial V-W/Ti catalyst. Also, V-0.5Ce(SO 4 ) 2 /Ti shows an excellent durability in the presence of SO 2 and H 2 O, indicating to have prospects for the industrial application. Based on catalysts characterization and in-situ DRIFTS studies, a higher proportion of surface active oxygen generated by the introduction of Ce and a much faster H 2 reduction point out the improved redox properties of V-0.5Ce(SO 4 ) 2 /Ti, which results in a stronger NO oxidative activation and is confirmed by a more abundant formation of surface NO + and NO 3 − species. When exposed to SCR conditions where both NH 3 and NO are present, this enhanced NO activation can produce more reactive nitrite and/or NO + intermediates which then readily react with adsorbed NH 3 and decompose to N 2 and H 2 O, accounting for the improved SCR activity of V-0.5Ce(SO 4 ) 2 /Ti at low temperatures. The addition of Ce(SO 4 ) 2 also provides abundant reactive acid sites and adsorbed NH 3 species thus increase. Even after Na poisoning, adequate surface acidity and redox properties still remain. Furthermore, relatively higher contents of V-OH are preserved owing to the interaction between Na and O S O, acting as a protection for the active sites. These promotional effects contribute to the better alkali resistance of V-0.5Ce(SO 4 ) 2 /Ti. Therefore, all the results suggest that V-0.5Ce(SO 4 ) 2 /Ti is a promising candidate as a catalyst for NH 3 -SCR in coal-fired power plants, especially under high Na-content conditions. [ABSTRACT FROM AUTHOR]

A post-plasma catalysis system has been developed for the removal of methanol over Mn–Ce oxide catalysts with different Mn/Ce molar ratios at low temperatures. The Mn 50 Ce 50 oxide catalyst (Mn/Ce = 1:1) shows the best performance in terms of methanol removal efficiency and energy efficiency of the plasma-catalytic process. The maximum methanol removal efficiency of 95.4% can be achieved at a discharge power of 15 W and a gas flow rate of 1 L/min, while the highest energy efficiency of the plasma-catalytic process is 47.5 g/kW h at 1.9 W. The combination of plasma and Mn–Ce catalysts significantly reduces the formation of major by-products (methane, formaldehyde and formic acid) based on the Fourier transform infrared spectra. Possible reaction mechanisms and pathways of the post-plasma catalytic removal of methanol are also proposed. A three-layer back propagation artificial neural network (ANN) model has been developed to get a better understanding of the roles of different process parameters on methanol removal efficiency and energy efficiency in the post-plasma catalytic process. The predicted data from the ANN model show a good agreement with the experimental results. Catalyst composition (i.e. Mn/Ce ratio) is found to be the most important factor affecting methanol removal efficiency with a relative importance of 31.53%, while the discharge power is the most influential parameter for energy efficiency with a relative weight of 30.40%. These results indicate that the well-trained ANN model provides an alternative approach for accurate and fast prediction of the plasma-catalytic chemical reactions. [ABSTRACT FROM AUTHOR]

• DFT found defective sites on δ-MnO 2 displayed higher Hg0 removal potential. • Mo-adjusted δ-MnO 2 nanosheet achieved excellent Hg0 removal efficiency. • 1.25Mo2 Mn exhibited superior catalytic oxidation of Hg0 to Hg2+ performance. • Mo showed promotional defective and dispersive effect of δ-MnO 2 nanosheet. • Synergistic interactions between the MnO 2 nanosheet and MoO 3 were adjusted. The challenge of Hg0 emission control has necessitated the development of catalytic oxidation technology. Herein, a combination of experimental and computational approach to explore the potential over Mo-Mn catalysts was conducted. Series of catalysts were synthesized and characterized with varying Mn and Mo loading (1–10%). Among the various compositions, 1.25Mo2 Mn catalyst exhibited the best Hg0 removal performance with Hg0 removal efficiency > 98% (oxidation ratio > 50%, and better stability over 10 h period at 250 °C). Most importantly, the synergistic interaction between MoO 3 and defective δ-MnO 2 nanosheet was promoted by the adjusted activation energy, bond strength, Brønsted acidic sites and defects, which facilitated the catalytic oxidation of Hg0 to Hg2+. Furthermore, DFT calculations suggested that the role of Mo enabled the reduction in the energy barrier for the desorption step, which was defined as the rate-determining step for catalytic oxidation of Hg0 on Mn-based catalyst. [ABSTRACT FROM AUTHOR]