Structural evolution and catalytic performance of DuPont V-P-O/SiO2 materials designed for fluidized bed applications

Structure–Reactivity Correlations in Vanadium‐Containing Catalysts for One‐Pot Glycerol Oxidehydration to Acrylic Acid

“…Hence, it can be concluded that vanadium is mainly present in VO-WO x as extra-framework species, either deposited on the externals urface or inside the hexagonal channels. [27] Raman spectroscopy was used to improvet he understanding on the structure of the various catalytic systemsp repared, particularly to shed light on the nature of the vanadium speciesi nt he HTB-like materials. For both CoAPO and VCoAPO catalysts,n oc hanges are observed in the diffraction patterns, which confirms the insertion of cobalt and vanadium in the oxide framework as tetrahedral units.…”

“…[14] Untreated WO x and WV,t hat is, fresh samples still containing ammonium ions in the hexagonal channels, were used as the starting materials for ion exchange. [27] Particularly,w eu sed its calcined form. [58] Precisely,W O x was exchanged with VO 2 + ions (sample VO-WO x ).…”

“…[22,23] Interestingly,t he commonp oint of all these catalytic systemsi st he presence of vanadium as one of the main (or only) redoxe lements;h owever,d espite this leitmotif, the catalytic behavioro ft hese mixed oxides is fairly different. [27] Remarkable structure-reactivity correlations werer evealed for the one-pot oxidehydration of glycerolt hat shed light on the different behaviors of vanadium as af unction of the physicala nd chemical features of the oxide in which it was present.V -free parentm aterials were also studied as reference materials for both characterization and catalytic tests purposes. The environment that characterizes the vanadium contour in the differentc atalytic systems makes it possible to forge its properties, weakening some of them in favor of others.…”

Glycerol oxidehydration to acrylic acid on complex mixed-metal oxides

“…Generally speaking, all the K-containing catalysts present a lower BET area than WV-3, which indicates that K-ions block the channels running along the c-direction of HTBs and/or form additional species on the catalyst surface that have low specific surface area. The VPP catalyst used is an industrial sample commercialized by DuPont, whose properties were extensively studied and reported in literature [119,120]; particularly, we used the calcined oxide. This sample is made by micrometric spheres with a core of VPP-phase (ca.…”

“…So as to better examine these peculiar results, selected mixed oxides where used as reference materials: (i) W-V-oxides with HTB structure, (ii) Vcontaining Al-P-(Co)-oxides, (iii) commercial Vanadyl Pyrophosphate -VPP-(DuPont, calcined [119]) and (iv) a V-exchanged hexagonal-tungsten oxide. The results obtained clearly highlight that an important structure-reactivity correlation exists and governs the redox features of vanadium along the oxidation step.…”