Preparation of super-microporous WO3–SiO2 olefin metathesis catalysts by the aerosol-assisted sol–gel process

Well-dispersed sulfated mesoporous WO 3 /SiO 2 hybrid colloidal spheres: High-efficiency catalysts for the synthesis of fatty acid alkyl esters

“…S1) show two intense bands which are assigned to asymmetric (2925 cm À1 ) and symmetric (2853 cm À1 ) stretching vibrations of C-CH 2 in the methylene chains. The sharp bands in the region of 1400-1500 cm À1 are attributed to the deformation of -CH 2 -and -CH 3 of the incorporated surfactants [14]. The band in the region around 3010 cm À1 is clearly observed, which is assigned to C-CH 3 asymmetric stretching and N-CH 3 symmetric stretching vibrations of solid surfactant [15].…”

“…Among transition metal oxides, tungsten oxide in various nanostructure morphologies has afforded great potential in a wide range of applications, which include heterogeneous catalysts, chromogenic devices, solar-energy devices, and field electron emission [12][13][14][15][16]. Although various hierarchical WO 3 structures with different morphologies have been synthesized by a variety of methods in recent years [13][14][15][16][17][18], with regard to the synthesis of mesoporous multicomponent hybrid colloidal spheres composed of WO 3 and other oxides, however, the research is scarce.…”

“…Although various hierarchical WO 3 structures with different morphologies have been synthesized by a variety of methods in recent years [13][14][15][16][17][18], with regard to the synthesis of mesoporous multicomponent hybrid colloidal spheres composed of WO 3 and other oxides, however, the research is scarce. In this presentation, the WMWCSs were prepared with hexadecyltrimethyl ammonium phosphotungstic (W-6) as precursor and hexadecyltrimethyl ammonium bromide (CTAB) as template.…”

Innovative Sol‐Gel Routes for the Bottom‐Up Preparation of Heterogeneous Catalysts

“…In this context it appears interesting to prepare catalysts with a high dispersion of the active elements. Thus, MoO 3 ‐SiO 2 ‐Al 2 O 3 , WO 3 ‐SiO 2 and WO 3 ‐SiO 2 ‐Al 2 O 3 formulations have been prepared by the aerosol‐assisted sol‐gel process. Mo and W precursors could be either a heteropolyanion or the chloride.…”

Effects of calcination and pretreatment temperatures on the catalytic activity and stability of H2-treated WO3/SiO2 catalysts in metathesis of ethylene and 2-butene

“…Considering the dispersion of tungsten on the silica support (as conrmed by XRD and TEM results), it was found that the H 2 -treated non-calcined catalysts exhibited the activity higher than the H 2 -treated calcined catalysts, and the pretreatment temperature at 650 C of the H 2 -treated noncalcined catalyst showed the highest activity, indicating that better dispersion of tungsten on the silica support exhibited the high activity of metathesis of ethylene and 2-butene to produce propylene. 14,26,38 Moreover, the TEM mapping results also conrmed that the H 2 -treated calcined catalysts showed the more tungsten agglomerates dispersed on the surface silica support than the H 2 -treated non-calcined catalysts, indicating poor tungsten dispersion on the support. Additionally, the UVVis and Raman results indicated that the higher amount of isolated tetrahedral tungsten oxide was active species for metathesis reaction.…”