Synthesis, Characterization, and Activity Studies of Vanadia Supported on Zirconia and Phosphorus-Modified Zirconia

Abstract

A series of catalysts with vanadia contents varying between 1 and 14 wt % were prepared by the wet impregnation technique on zirconia and phosphorus-modified zirconia. The catalysts were characterized by employing X-ray diffraction (XRD), electron spin resonance (ESR) spectroscopy, 51V, 31P, and 1H solid-state magic angle spinning nuclear magnetic resonance (MAS NMR), Fourier transform Raman spectroscopy (FT-Raman), diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), and Brunauer−Emmett−Teller (BET) surface area measurements. The activities of the catalysts were determined by an ethanol partial oxidation reaction. 51V solid-state NMR studies of both series of catalysts indicated the presence of tetrahedral vanadate species at lower loadings, and octahedrally coordinated vanadium species at higher concentrations. DRIFTS studies of the catalysts were in conformity with NMR studies as the vibrations corresponding to tetrahedral vanadate species were observed at low V2O5 loadings and at higher vanadia contents the vibrations corresponding to polymeric decavanadate species were seen. All of the XRD, ESR, 51V solid-state NMR, FT-Raman, and DRIFTS results indicated weaker interaction of vanadia with zirconia support upon phosphate modification. Activity studies were in agreement with spectroscopic data, as reflected in higher ethanol partial oxidation activities of the V2O5/ZrO2 catalysts.

Determining the Structure of Silica-Supported Monomeric Vanadium Oxide Catalysts Based on Synthesis Method and Spectral Data from Theoretical Calculations

“…The molecular structure of these supported vanadium oxide species has been studied by a wide variety of spectroscopic techniques, including Raman, 51 V NMR, UV-vis-near-infrared, extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge spectroscopy, electron spin resonance, and X-ray photoelectron spectroscopy. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] Several review papers, which describe the current understanding of these catalytic systems, [18][19][20][21] can be found in the literature.…”

Efficient oxidative dehydrogenation of ethanol by VOx@MIL-101: On par with VOx/ZrO2 and much better than MIL-47(V)

“…Vanadium based catalysts belong to the most investigated and promising catalytic systems for the ODH of ethanol. Previous studies demonstrated that catalytic activity of the catalyst depend on nature of the support and speciation of vanadium complexes [50][51][52][53][54]. Regarding the activity and selectivity pair of parameters, the tetrahedral oligomeric vanadate species seems to be the most appropriate catalytic entities [50,52,55,56].…”

Spectroscopic Study of V2O5 Supported on Zirconia and Modified with WO3

“…Vanadium oxides are widely used as catalysts in oxidation reactions, for example, the oxidation of sulfur dioxide, carbon monoxide, and hydrocarbons. − These systems have also been found to be effective catalysts for the oxidation of methanol to methylformate , and for the selective catalytic reduction of nitrogen oxide. , Much research has been done to understand the nature of active sites, the surface structure of catalysts, and the role played by the promoter of the supported catalysts, using infrared (IR), X-ray diffraction (XRD), electron spin resonance (ESR), and Raman spectroscopy. ,− So far, silica, titania, zirconia, and alumina − have been commonly employed as the vanadium oxide supports.…”