Synthesis of porous and acidic complex metal oxide catalyst based on group 5 and 6 elements

Multielement Crystalline and Pseudocrystalline Oxides as Efficient Catalysts for the Direct Transformation of Glycerol into Acrylic Acid

“…Figure 1 shows the XRD patterns of catalysts prepared by heat treatment at 600 8C in nitrogen. These patterns are similar to those reported for molybdenum-and tungsten-based mixed oxides by Murayama et al [23] According to these authors, samples with higher molybdenum contents were characterized by two peaks at 2q = 22 and 468 that could be attributed to the (0 0 1) and (0 0 2) planes of a bronze-type frame, which suggested that these materials had a layer-type crystal structure. Interestingly, crystallinity is considerably improved for the sample containing a higher amount of vanadium (WMoV-2); this emphasizes the conclusion formerly drawn by our group that vanadium has a stabilizing effect on the HTB structure.…”

“…[14] By keeping the W/V ratio constant and increasing the amount of molybdenum (i.e., WMoV-3 and WMoV-4), the XRD patterns are dominated by two diffraction maxima at 2q % 22 and 468, whereas broad diffraction maxima appear at 2q % 27, 32, 50, and 558 ( Figure 1 c and d). These patterns are similar to those reported for molybdenum-and tungsten-based mixed oxides by Murayama et al [23] According to these authors, samples with higher molybdenum contents were characterized by two peaks at 2q = 22 and 468 that could be attributed to the (0 0 1) and (0 0 2) planes of a bronze-type frame, which suggested that these materials had a layer-type crystal structure. These diffraction maxima can correspond to the (0 0 1) and (0 0 2) d spacing of any structure based on the corner-sharing octahedral ReO 3like framework with a basic cell parameter of about 3.8 .…”

Hydrothermal synthesis of octahedra-based layered niobium oxide and its catalytic activity as a solid acid

“…26,27 A metal oxide complex that possesses a similar layered structure in the c-direction by corner-sharing of MO 6 (M = Mo, W, V, Ta, Nb) octahedra has been synthesized by a hydrothermal method. [28][29][30] These catalysts were found to function as solid acids, the property of which was understood from a structural point of view.…”

NH3-efficient ammoxidation of toluene by hydrothermally synthesized layered tungsten-vanadium complex metal oxides

“…Briefly, the results showed three structural features: (i) layered-type structure along c-axis direction characterized by diffraction peaks at 2θ = 23° and 46° (XRD), (ii) long rod-shaped crystal morphology due to stacking of the layers along the c-axis by sharing the apex oxygen (STEM), (iii) the presence of micropore (N 2 -adsorption). Considering the structural model that we have proposed for the similar binary metal oxides consisted of group 5 and 6 elements [17][18][19][20][21][22][23], the structural model of W-V-O is proposed in Fig. 1.…”

“…The single phase Mo-V-P catalyst with similar structure also catalyzed the ammoxidation of propane [19]. Recently, we have extended the hydrothermal synthetic methodology to metal oxides consisted of various group 5 and 6 elements [20][21][22][23], and prepared a series of binary metal oxides (such as W-Ta-O [20,23], W-Nb-O [21] and W-V-O complex oxides [22]) with similar microporous and layered structure as the orthorhombic Mo 3 VO x [18]. Considering the fact that WOx is an well known acidic co-catalyst of V-based catalysts [24][25][26][27], we have hypothesized that the W-V-O oxides act as effective catalysts for the ammoxidation.…”