A structural explanation for the polymorphism of the α form of anhydrous vanadyl phosphate

Catalytic Properties of Silver Vanadium Phosphates in n‐Butane Oxidation – Considerations on the Impact of the [VxOy] Substructure

“…The highly active and selective (VO) 2 P 2 O 7 catalyst has the optical basicity K = 0.49 [33]. Since Ag + ions (K = 1.25 for [20,22,36,38,39].…”

Transient studies of low temperature catalysts for methane conversion. Final report, [September 1992--March 1996]

“…An irreversible phase change from al-VOP04 to a11-VOP04 has been reported to take place at 993 K (9). These two phases are very similar and there are only small differences in the relative positions of the V and P atoms in the structure (18,19). It is likely that either the VPO-u sample has undergone the phase change at lower temperature than reported, or that the spectra of the VPO sample showed in figure 4 represents a state in which a partial phase change has occurred.…”

“…The aj-VOP04 can be described as VOPO4 layers lying in the ab plane as well, but the VO6 octahedra are also sharing the axial 0 atoms with other V atoms forming chains of octahedra running along the c axis (18)(19)(20). aI-VOPO, is thermally stable until around 993 K, where it undergoes an irreversible transformation to the aI1 phase, which has basically the same layered structure as the aI-phase, but it differs in the relative position of the vanadyl group (V=O) as compared to the tetrahedra.…”

The Mechanism of Alkane Selective Oxidation by the M1 Phase of Mo–V–Nb–Te Mixed Metal Oxides: Suggestions for Improved Catalysts

“…[18,19] This opens the possibility that the V +5 sites responsible for alkane and furan activation may come from the small amounts of VOPO4. [20] As a result, we considered three phases of VOPO4: αΙ, [21] αΙΙ, [22] and the proposed X1-phase. [23,24] We found that…”