Influence of Phase Composition of Bulk Tungsten Vanadium Oxides on the Aerobic Transformation of Methanol and Glycerol

Abstract

A series of W-V-O catalysts with different m-WO 3 and h-WO 3 phase contents were hydrothermally synthesized by employing different tungsten, vanadium, and ammonium precursors and characterized by powder XRD, N 2 adsorption, SEM, X-ray energy-dispersive spectroscopy, thermogravimetric analysis, Raman and FTIR spectroscopy, NH 3 temperature programmed desorption, H 2 temperature-programmed reduction, and XPS. Finally, the acid/redox properties were analyzed by using aerobic transformation of methanol as a characterization reaction. A correlation between phase composition as well as acid and redox properties was observed, which were correlated to the catalytic performance of the title materials in a one-pot [a]

Tungsten-titanium mixed oxide bronzes: Synthesis, characterization and catalytic behavior in methanol transformation

“…Thereby, redox sites lead to the oxidative dehydrogenation of methanol or partial oxidation of DME, yielding formaldehyde. On the other hand, acid sites (Lewis and/or Brönsted) lead to methanol dehydration to yield dimethyl ether [32,56]. This association between the reaction product and the type of active sites is more suitable when working at low methanol conversion.…”

“…1A and Fig. 1B respectively [28,32], which is present as the major phase in both as-prepared and heat-treated materials (Fig. 1).…”

“…For instance, they have been applied in the partial oxidation of propene [26] or the catalytic abatement of trichloroethylene [27]. Among all tungsten-containing oxide bronze systems with well-defined structures, tetragonal (TTBs) [26,27] and hexagonal tungsten bronzes (HTBs) [28][29][30][31][32][33], have been the most studied systems for catalytic applications. In the case of HTB-based materials (formed by an array of corner-sharing octahedra, presenting hexagonal 6-member channels along c crystallographic direction), they have found more diversified catalytic applications, like glycerol dehydration and oxidehydration [28][29][30], ethanol and methanol dehydration and oxidation [31][32], benzyl alcohol/toluene alkylation [33], or as electrocatalysts [34].…”

Preguntas orientadoras para la síntesis de catalizadores y su uso en reacciones de oxidación catalítica selectiva

“…Para este caso y con base en las sustancias intermedias formadas, los diferentes productos de reacción se verán afectados por el tipo de reacción que ocurra. Así, dependiendo de los centros activos pueden ocurrir reacciones tipo ácido base o reacciones de oxidación-reducción [41]. En cuanto a las condiciones de reacción (cuarta pregunta orientadora) para reacciones en fase gaseosa, los aspectos que influyen directamente en la activación de los reactivos son la temperatura y la presión.…”

Reflux-synthesized bulk and diluted W-Nb-O mixed oxide bronzes for the valorization of short-chain oxygenates aqueous mixtures

“…Among the examples of tungsten oxide bronzes with interesting catalytic properties we can point out hydrothermally synthesized tetragonal tungsten bronzes for the partial oxidation of propylene [9] and the catalytic abatement of trichloroethylene [10], or hexagonal tungsten bronze materials (prepared either by hydrothermal or reflux methods) for the aerobic transformation of glycerol into acrolein and acrylic acid [11][12][13]. Also they have been applied in alkylation reactions [14] or as electrocatalysts [15].…”