Catalytic properties of transition metal carbides I. Preparation and physical characterization of bulk mixed carbides of molybdenum and tungsten

Production of Terephthalic Acid from Lignin-Based Phenolic Acids by a Cascade Fixed-Bed Process

“…As shown in Figure , the catalyst MoWBO x /AC exhibited carbide peaks at 228.6 and 231.6 eV for Mo 2 C and 31.3, 33.4 eV for W 2 C, respectively. The results are in good agreement with the binding energy of molybdenum and tungsten carbide species reported elsewhere. − The absorptions at 235.6 and 232.2 eV (Figure a) are assigned to MoO x (2 < x < 3) with a Mo 6+ dominant species in MoO x , according to the literature. − The corresponding atomic percentages of MoO x and Mo 2 C are 67.0% and 33.0%, respectively. The peaks at 37.2 and 35.2 eV (Figure b) are contributed from WO x (2 < x < 3), and the W 6+ species are the main component. − The atomic percentage of WO x and W 2 C are 63.2% and 36.8%, respectively.…”

“…The results are in good agreement with the binding energy of molybdenum and tungsten carbide species reported elsewhere. − The absorptions at 235.6 and 232.2 eV (Figure a) are assigned to MoO x (2 < x < 3) with a Mo 6+ dominant species in MoO x , according to the literature. − The corresponding atomic percentages of MoO x and Mo 2 C are 67.0% and 33.0%, respectively. The peaks at 37.2 and 35.2 eV (Figure b) are contributed from WO x (2 < x < 3), and the W 6+ species are the main component. − The atomic percentage of WO x and W 2 C are 63.2% and 36.8%, respectively. The presence of these oxidation states can be explained by partial oxidation of the carbide due to exposure to air during the course of sample preparation and transformation to the XPS equipment.…”

Kinetics and Mechanism of the Reaction between H2O2 and Tungsten Powder in Water

“…The W which binding energy corresponds to 32 eV may build either tungsten carbide or nonstoichiometric tungsten oxide. 52 Most probably that this phase is rather WO x than WC since apart from WO x , there were no traces of tungsten carbide observed in XRD diffraction pattern. WO 3 most probably forms thin amorphous layer on the W surface, since it was not possible to detect it by XRD measurements.…”

Tungsten Carbide Nanoparticles as Efficient Cocatalysts for Photocatalytic Overall Water Splitting

“…[21] For a-WC samples synthesized in the range of 1223-1373 K, the W 4f spectra show peaks at binding energies assigned to WC at 32.2 (W 4f 7/2 ) and 34.4 eV (W 4f 5/2 ), which closely agrees with reported values. [15,43,44] These a-WC samples showed signals emitted from the partially oxidized surface of the materials because of the O 2 passivation treatment and unavoidable exposure of the nanoparticles to the ambient conditions. The intensity of the W 4f signals assigned to the WO 3 species (35.8 and 38.0 eV) decreased with an increase in temperature, whereas the carbidic W 4f signal intensity (32.2 and 34.4 eV) increased with increasing temperature, which corresponds to the concrete formation of WC, as observed in the XRD patterns (Figure 2 B).…”