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Engineering the interface between different components of heterogeneous catalysts at nanometer level can radically alter their performances. This is particularly true for ceria-based catalysts where the interactions are critical for obtaining materials with enhanced properties. Here we show that mechanical contact achieved by high-energy milling of CeO2–ZrO2 powders and carbon soot results in the formation of a core of oxide particles wrapped in a thin carbon envelope. This 2D nanoscale carbon arrangement greatly increases the number and quality of contact points between the oxide and carbon. Consequently, the temperatures of activation and transfer of the oxygen in ceria are shifted to exceptionally low temperatures and the soot combustion rate is boosted. The study confirms the importance of the redox behavior of ceria-zirconia particles in the mechanism of soot oxidation and shows that the organization of contact points at the nanoscale can significantly modify the reactivity resulting in unexpected properties and functionalities.

dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: the role of the interface periphery, Applied Catalysis B, Environmental http://dx.doi.org/10. 1016/j.apcatb.2015.07.027 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The catalytic tests in deN 2 O reaction revealed that the 10 wt.% of cobalt spinel in supported system is able to reproduce the activity of bare Co 3 O 4 catalyst. However, it was found that the catalyst with the lowest content of Co 3 O 4 equal to 1 wt.% exhibits the highest apparent reaction rate per mass of the spinel active phase. The observed activity was explained basing on the transmission electron microscopy analysis in terms of the dispersion of spinel phase over ceria support. A simple model that accounts for the observed strong dispersion effect is proposed. It consists in a two-step mechanism, where N 2 O is dissociated on the spinel nanograins and the resultant oxygen species are preferentially recombined at the Co 3 O 4 /CeO 2 interface periphery.

Please cite this article in press as: V. Rico-Pérez, et al., Synergic effect of Cu/Ce 0.5 Pr 0.5 O 2-␦ and Ce 0.5 Pr 0.5 O 2-␦ in soot combustion, Appl. Catal. B: Environ. (2016), http://dx. a b s t r a c tA series of 5%Cu/Ce 0.5 Pr 0.5 O 2-␦ and Ce 0.5 Pr 0.5 O 2-␦ mixed oxides have been prepared and combined in different ratios. The resulting catalysts have been characterized by N 2 adsorption, XRD, Raman spectroscopy and H 2 -TPR and tested for soot combustion by means of temperature-programmed experiments. The optimum catalyst for soot combustion in NO x /O 2 /N 2 atmosphere is the mixture containing 40% Cu/Ce 0.5 Pr 0.5 O 2-␦ and 60% Ce 0.5 Pr 0.5 O 2-␦ . This mixture is more active than a reference catalyst containing the same amount of copper distributed in the whole Ce-Pr mixed oxide support. The benefit of mixing Ce 0.5 Pr 0.5 O 2-␦ particles with and without copper in a single catalyst formulation is that the participation of the two soot combustion mechanisms based on active oxygen and NO 2 , respectively, is optimized. The particles with copper mainly promote the catalytic oxidation of NO to NO 2 (the NO x -assisted mechanism) while those without copper are more effective in promoting the active oxygen mechanism. If copper is loaded homogeneously in all the Ce 0.5 Pr 0.5 O 2-␦ particles, the positive effect of copper improving NO 2 production is offset by the lower efficiency of the active oxygen mechanism, due to a lack of active oxygen on the Ce 0.5 Pr 0.5 O 2-␦ support.

CuO supported on CeO2 and Ce0.9X0.1O2, where X is Zr, La, Tb or Pr, were synthesized using nitrate precursors, giving rise ceria based materials with a small particle size which interact with CuO species generating a high amount of interfacial sites. The incorporation of cations to the ceria framework modifies the CeO2 lattice parameter, improving the redox behavior of the catalytic system. The catalysts were characterized by X-ray Diffraction (XRD), High-resolution Transmission Electron Microscopy (HRTEM), Raman spectroscopy, thermoprogrammed reduction with H2 (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The catalysts were tested in the preferential oxidation of CO under a H2-rich stream (CO-PROX), reaching conversion values higher than 95% between 115-140 ºC and being the catalyst with 6 wt.% of Cu supported on Ce0.9Zr0.1O2 (sample 6CUZRCE) the most active catalyst. The influence of the presence of CO2 and H2O was also studied simulating a PROX unit, taking place a decreasing of the catalytic activity due to the inhibitor effect both CO2 and H2O.

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Simultaneous catalytic oxidation of carbon monoxide, hydrocarbons and soot with Ce-Zr-Nd mixed oxides in simulated Diesel exhaust conditions, Applied Catalysis B, Environmental (2014), http://dx.doi.org/10. 1016/j.apcatb.2014.07.013 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Diesel vehicles running with sulfur-free fuel, since it maintained significant 91 activity for soot combustion even in the presence of H 2 O and CO 2 . 92As far as we know, the simultaneous ceria-catalyzed combustion of soot, 93CO, and hydrocarbons has not been studied and reported in the literature, and 94 this is one of the goals of the current study. In addition, the positive effect of recorded between 10 and 80º (2θ) with a step of 0.025º. 124Raman spectra were recorded in a Bruker RFS 100/S Fourier Transform 125Raman Spectrometer with a variable power Nd-YAg laser source (1064 nm). 126The laser beam was focused on the sample in a 180º backscattering 127 configuration and 128 scans at 100 mW laser power were recorded. The BET specific surface area of the oxides was determined by physical respectively, of each gas pollutant (CO, propylene and benzene). 173Soot conversion was determined from CO 2 and CO evolved (both 174 followed by gas chromatography) after subtracting the stoichiometric amounts precursor, but this would be hindered Nd 3+ doping. 244Raman spectra included in Figure 3 also provided information about the 245 structure of the oxides, and supported some conclusions of the XRD analysis. 261The BET specific surface areas also showed important differences

Abstract:The effect of the calcination conditions on the catalytic activity for N2O decomposition of 2.5% RhOx/CeO2 catalysts has been investigated. Ramp and flash calcinations have been studied (starting calcinations at 25 or 250/350 °C, respectively) both for cerium nitrate and ceria-impregnated rhodium nitrate decomposition. The cerium nitrate calcination ramp has neither an effect on the physico-chemical properties of ceria, observed by XRD, Raman spectroscopy and N2 adsorption, nor an effect on the catalysts performance for N2O decomposition. On the contrary, flash calcination of rhodium nitrate improved the catalytic activity for N2O decomposition. This is attributed to the smaller size of RhOx nanoparticles obtained (smaller than 1 nm) which allow a higher rhodium oxide-ceria interface, favoring the reducibility of the ceria surface and stabilizing the RhOx species under reaction conditions.