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A monometallic Ni and a bimetallic Ni-Fe catalyst were used in the aqueous phase hydrogenation of xylose in batch conditions (T = 50 -150 °C, PH2 = 10 -30 bar, xylose mass fraction in water = 3.7 -11.0 wt.%) to evidence the benefits of promoting Ni by Fe. The activity of the catalysts increased with temperature, but a temperature of 80 °C allowed minimizing nickel leaching at full conversion. The presence of reduced Fe at the surface of the bimetallic nanoparticles increased both the first-order apparent rate constant and the adsorption constant of xylose. The catalytic activity of Ni/SiO2 strongly declined and no deactivation was found for the Ni-Fe catalyst. A restructuring of the bimetallic nanoparticles took place, as the size of the metal particles and the Fe proportion in the surface layers increased, suggesting a flattening and coalescing of the particles over the silica surface.

Grafting of [W(2)(NMe(2))(6)] onto dehydroxylated silica affords the well-defined surface species [([triple bond, length as m-dash]Si-O)W(2)(NMe(2))(5)], characterized by elemental analysis, and infrared, Raman and NMR spectroscopies, and the catalytic reactivity of this supported tungsten(III) d(3)-d(3) dimer and of its alkoxide derivatives towards alkynes has been probed.

Active phase of a catalyst: Using the 3D structural characterization of the environment around Mo atoms provided by X‐ray absorption near‐edge structure spectroscopy (left; spectrum of the MoK edge) and DFT calculations, the molecular‐scale structure of a TiO2‐supported molybdenum oxide catalyst was defined. The structure consists of Mo octahedra arranged in a six‐membered ring.

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perovskites for HCHO oxidation: the role of oxygen species on the catalytic mechanism, Applied Catalysis B:

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Mn-or Cu-substituted LaFeO 3 -based three-way catalysts: Highlighting different catalytically operating modes of La 0.67 Fe 0.8 M 0.2 O 3 (M=Cu, Mn)