Caractérisation structural multiéchelle de catalyseurs industriels de type vanadophosphate

International audienc

Hydrates and polymorphs of lead squarate Pb(C4O4): Structural transformations studied by in situ X-ray powder diffraction and solid state NMR

International audienceConsidering the low dimensionality of the crystal structure of the known lead squarate tetrahydrate, Pb(C4O4)·4H2O, the thermal reactivity of the powdered compound and structural studies of lower hydrates have been investigated from X-ray single-crystal and powder diffraction data, solid state NMR and thermal analyses. It is shown that Pb(H2O)(C4O4) and two polymorphs of anhydrous PbC4O4 can be formed within different conditions. The departure of the water molecules leads to the condensation of initial inorganic chains into 2D or 3D-type crystal structures. The full decomposition of the squarate ligand provides successive lead oxides

Synthesis, crystal structure of the ammonium vanadyl oxalatophosphite and its controlled conversion into catalytic vanadyl phosphates

International audienc

Combining in situ XRPD and solid state NMR to study ω-VOPO4 among industrial vanadium phosphate catalysts

International audienc

Combined in-situ X-ray powder diffraction and solid-state NMR study of a new NaVOPO4 polymorph

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Combined NMR and X-ray diffraction study of structural aspects, dynamics and charge ordering mechanism in LixVOPO4.2H2O intercalation compounds

International audienceWe carried out a detailed investigation of the local ordering and dynamics of the lithium intercalation in paramagnetic LixVOPO4.2H2O (with 0 < x ≤ 1) materials. This question was addressed using a combination of X-ray diffraction, 31 P and 7 Li MAS NMR experiments. We first studied the structure of the fully ordered end-member of the series, Li1VOPO4.2H2O, revisiting the X-ray single crystal diffraction data on the basis of the information provided by 31 P MAS NMR. We then carried out 7 Li MAS and exchange NMR experiments and 31 P MAS experiments on the polycrystalline powders obtained after partial lithium insertion in VOPO4.2H2O phases. These experiments evidenced an unexpected ageing of the material related with lithium dynamics between the VOPO4 layers and a V 4+ /V 5+ charge ordering mechanism within the layers

31P and 51V NMR studies of VOPO4 catalysts: vanadium decoupling, CSA amplification and NMR parameter calculations

International audienc

31P NMR applied to vanadium phosphate catalysts: crucial influence of 51V decoupling strategies

International audienc

31P and 51V NMR studies of VOPO4 catalysts: vanadium decoupling, CSA amplification and NMR parameter calculations

International audienc

Etude in situ par DRX sur poudre et RMN du solide de catalyseurs industriels vanadophosphates : focus sur la phase ω-VOPO4

International audienc