Affiliation: | (1) Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, 113 Tokyo, Japan;(2) Present address: Graduate School of Environmental Earth Science, Hokkaido University, 060 Sapporo, Japan |
Abstract: | Anisotropic oxidation of crystallites of vanadyl pyrophosphate ((VO)2P2O7) has been demonstrated by Raman spectroscopy with samples having different microstructures. Oxidation of these samples by O2 produced X1 phase,- and-VOPO4 phases. The relative peak intensity of the X1 phase to the other phases correlated well with the ratio of the (100) plane to the side planes (surface area-basis). This correlation showed that the (100) plane was oxidized to X1 phase and the side planes to- and-VOPO4. For example, thin plate-like (VO)2P2O7, of which the (100) fraction is 98%, was oxidized almost exclusively to X1 phase. But when it was fractured into small plates to increase the side planes and then oxidized,- and-VOPO4 were detected in addition to the X1 phase. These results are consistent with our previous conclusion that the (100) plane of (VO)2P2O7 is selective, but side planes are non-selective for catalytic oxidation ofn-butane. |