Highly Active Doped Mesoporous KIT-6 Catalysts for Metathesis of 1-Butene and Ethene to Propene: The Influence of Neighboring Environment of W Species

Abstract

Tungsten-doped mesoporous KIT-6 (W-KIT-6), mesoporous silica supported WO 3 /KIT-6, and traditional silica supported WO 3 /SiO 2 catalysts have been successfully synthesized and tested for catalytic metathesis of 1-butene and ethene to propene. The resultant materials were comprehensively characterized by XRD, BET, TEM, UV−DRS, IR, XPS, H 2 -TPR, and TGA. For W-KIT-6 catalysts, high concentration of W 5+ species by XPS and the difficulty of reduction of W species by TPR suggested the incorporation of W species into the KIT-6 framework. The studies of smallangle XRD, BET, and TEM illustrated that the 3D ordered mesoporous structure and their high surface area of KIT-6 were maintained in W-KIT-6. The doped W-KIT-6 illustrated superior catalytic performance to the supported WO 3 /KIT-6 and WO 3 /SiO 2 catalysts. The origin of catalytic performance enhancement for W-KIT-6 was preliminarily discussed and was assigned to the incorporation of W species into KIT-6 framework. This study demonstrated the influence of neighboring environment of active components on catalytic performance and was helpful to design metathesis catalysts.

Metathesis of Ethylene and Trans-2-Butene over MgO Admixed WO3/SiO2 Catalysts

“…Nevertheless, the surface and bulk structures of the WO3/SiO2 catalysts in the present work were not altered when physically mixed with the MgO catalysts and tested in the metathesis of ethylene and 2-butene as confirmed in our previous work by the XRD, Raman, and UV-Vis spectroscopy [21]. Hu et al also studied the metathesis of 1-butene and ethylene to propylene on the W-contained catalysts mixed with MgO [22]. It was confirmed that MgO did not catalyze the reaction of 2-butene and ethylene for propylene.…”

Efficient NH3-SCR removal of NOx with highly ordered mesoporous WO3(χ)-CeO2 at low temperatures

“…6d. With increasing tungsten content, the peak position of these five catalysts had no significant change, suggesting that neighboring environment of the W 6+ cations stayed the same to a certain extent [22,23]. However, it’s worth noting that peak intensities enhanced gradually with the increasing of WO 3 concentration.…”

“…In order to prepare the highly ordered mesoporous WO 3 (1)-CeO 2 , 3D mesoporous KIT-6 silica was used as a hard template [23]. Typically, 1.2 g of (NH 4 ) 6 W 7 O 24 ·6H 2 O, 1.2 g of oxalic acid and 1.8 g of Ce(NO 3 ) 2 ·6H 2 O were dissolved in 30 mL deionized water, and then 1.0 g of KIT-6 was added to the above mixture.…”

Modification Effects of B2O3 on The Structure and Catalytic Activity of WO3-UiO-66 Catalyst

“…All of the spectra were obtained by deducting the spectrum of the support UiO-66. For comparison, the UV–vis DRS spectrum of bulk WO 3 is also presented, exhibiting a strong absorption band at 450 nm with a weak shoulder at 360 nm, accompanied by relatively weaker bands at 230 and 280 nm (Figure 5a), and these bands are attributed to crystalline WO 3 [5,46], isolated WO 4 tetrahedral species [47], and isolated or low condensed oligomeric tungsten oxide species in octahedral coordination [48], respectively. When compared to bulk WO 3 , different WO 3 /UiO-66 samples absorbed at 230, 280, and 310 nm (Figure 5b–e), which was ascribed to the absorption of isolated or low condensed oligomeric tungsten oxide species.…”