In situ sulphated CuOx/ZrO2 and CuOx/sulphated-ZrO2 as catalysts for the reduction of NOx with NH3 in the presence of excess O2

Sulphated catalysts containing the same amount of sulphates (2.6 SO4 nm2) and a different amount of copper (0.3–3.9 Cu atoms nm2), Cu/SZ, were prepared by impregnation of sulphated-ZrO2 with toluene solutions of Cu(acetylacetonate)2. Sulphated catalysts containing the same amount of copper (0.3 or 2.5 atoms nm2) and a different amount of sulphates (up to 4.9 SO2 nm2), Cu/ZSg, were prepared by sulphation of CuOx/ZrO2 (Cu/Z) via the gas-phase. Samples were characterised by Fourier transformed IR spectroscopy. The selective catalytic reduction of NO with NH3 in the presence of excess O2 (SCR reaction), the NH3 + O2 and the NO + O2 reactions were studied in a flow apparatus. Activity and selectivity did not depend on the sulphation method used for catalyst preparation but depended on the amount of copper and sulphate, particularly on the sulphate/copper ratio. As on Cu/Z, on Cu/SZ CuII was active for both SCR and NH3 + O2 reactions. The presence of covalent sulphates caused lower reducibility of CuII to CuI and higher Lewis acid strength of CuI in Cu/SZ than in Cu/Z. For (i) SCR, (ii) NH3 + O2 and (iii) NO + O2, Cu/ZSg were less active than the parent Cu/Z. As the sulphate content in Cu/ZSg increased, the NO yield in the NH3 + O2 reaction markedly decreased, thus accounting for the increased selectivity in the SCR reaction. In CuOx/ sulphated-ZrO2 copper ions were less prone reversibly to undergo the redox process CuII/CuI. These findings provide new information on the role of copper and sulphate in determining the activity and selectivity for the SCR with NH

MCM-41 Supported Co-based Bimetallic Catalysts for Aqueous Phase Transformation of Glucose in Biochemicals

The transformation of glucose into valuable biochemicals was carried out on different MCM-41-supported metallic and bimetallic (Co, Co-Fe, Co-Mn, Co-Mo) catalysts and under different reaction conditions (150 °C, 3 h; 200 °C, 0.5 h; 250 °C, 0.5 h). All catalysts were characterized using N2 physisorption, Temperature Programmed Reduction (TPR), Raman, X-ray Diffraction (XRD) and Temperature Programmed Desorption (TPD) techniques. According to the N2-physisorption results, a high surface area and mesoporous structure of the support were appropriate for metal dispersion, reactant diffusion and the formation of bioproducts. Reaction conditions, bimetals synergetic effects and the amount and strength of catalyst acid sites were the key factors affecting the catalytic activity and biochemical selectivity. Sever reaction conditions including high temperature and high catalyst acidity led to the formation mainly of solid humins. The NH3-TPD results demonstrated the alteration of acidity in different bimetallic catalysts. The 10Fe10CoSiO2 catalyst (MCM-41 supported 10 wt.þ, 10 wt.%Co) possessing weak acid sites displayed the best catalytic activity with the highest carbon balance and desired product selectivity in mild reaction condition. Valuable biochemicals such as fructose, levulinic acid, ethanol and hydroxyacetone were formed over this catalyst

MCM-41 supported co-based bimetallic catalysts for aqueous phase transformation of glucose to biochemicals

The transformation of glucose into valuable biochemicals was carried out on different MCM-41-supported metallic and bimetallic (Co, Co-Fe, Co-Mn, Co-Mo) catalysts and under different reaction conditions (150 °C, 3 h; 200 °C, 0.5 h; 250 °C, 0.5 h). All catalysts were characterized using N2 physisorption, Temperature Programmed Reduction (TPR), Raman, X-ray Diffraction (XRD) and Temperature Programmed Desorption (TPD) techniques. According to the N2-physisorption results, a high surface area and mesoporous structure of the support were appropriate for metal dispersion, reactant diffusion and the formation of bioproducts. Reaction conditions, bimetals synergetic effects and the amount and strength of catalyst acid sites were the key factors affecting the catalytic activity and biochemical selectivity. Sever reaction conditions including high temperature and high catalyst acidity led to the formation mainly of solid humins. The NH3-TPD results demonstrated the alteration of acidity in different bimetallic catalysts. The 10Fe10CoSiO2 catalyst (MCM-41 supported 10 wt. þ, 10 wt. %Co) possessing weak acid sites displayed the best catalytic activity with the highest carbon balance and desired product selectivity in mild reaction condition. Valuable biochemicals such as fructose, levulinic acid, ethanol and hydroxyacetone were formed over this catalyst

Experimental investigation on the flow field and performances of a Savonius-Darrieus wind turbine

In this paper, measurements performed on a vertical axis wind turbine (VAWT) model are reported. The turbine is a combination of Savonius and Darrieus rotors to optimize performances in medium-low wind regimes. To this end, the turbine is positioned into a wind-tunnel to derive instantaneous and averaged velocity fields by means of Particle Image Velocimetry (PIV). PIV data allow to derive specific fluid flow phenomena on each single and on combined geometrical configurations. These results are also compared with electrical measurements to determine performances, efficiency and the best working conditions

HYBRI – A combined Savonius-Darrieus wind turbine: Performances and flow fields

In this paper, wind tunnel measurements on a model of a vertical axis wind turbine (VAWT) are reported. The turbine is a novel hybrid Savonius-Darrieus combined rotor which aims optimizing performances in medium-low wind regimes, by using a careful design of the shape, size and relative positions of Savonius and Darrieus blades. To this end, a dynamically scaled turbine model is tested in wind tunnel to derive instantaneous and averaged velocity fields by means of Particle Image Velocimetry (PIV), which allows deriving wakes and specific fluid flow phenomena on each single configuration (Savonius or Darrieus) and interactions on the combined geometry. These results are coupled with electrical measurements to determine global performances, efficiency and best working conditions for each separate turbine and for the combined turbine. Data are also compared with results obtained by other authors in previously reported combined hybrid configurations. The proposed system is able to work with good performances (power coefficient equal or slightly lower than 0.2), on an extended range of operative conditions, covering those of each component alone, i.e. for tip speed ratios between 0.5 and 4, in comparison to the ranges 0.5 ÷ 1 and 1.7 ÷ 4 of the used Savonius and Darrieus components. Motivations for the increased performances and working ranges reached by the proposed combined turbine, especially in the low tip speed ratio regime, are given as derived from detailed PIV velocity measurements

Decomposition of nitrous oxide on CoOx/ZrO2, CuOx/ZrO2 and FeOx/ZrO2 catalysts

CuOx/ZrO2, CoOx/ZrO2 and FeOx/ZrO2 catalysts were characterized and studied for the decomposition of nitrous oxid

Catalytic partial oxidation of methane on Ni/ZrO2 system for syngas production

Monoclinic ZrO2-supported Ni catalysts (Ni/Z) were much more active than unsupported Ni particles for the CH4 catalytic partial oxidation, Ni0 particles in the two systems being equal in size. A strong promoting effect of metal-support interaction on activity was thus apparent. Ni/Z catalysts obtained by different preparation procedures showed similar high catalytic activity and stability despite of markedly different Ni particle size distributions. Activation treatments apparently influenced the catalytic behaviour of the Ni particles; an oxidative+reductive activation treatment of the Ni/Z catalysts determined high activity and stability, whereas, omitting the oxidative step, oscillating activity occurred