プロパン酸化脱水素触媒マグネシウムピロおよびオルトバナデートの51V MAS NMRおよびXAFSから観測したレッドクス挙動(<特集>希土類系物質の精密合成,形態制御および機能物性)

概要

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To evaluate the redox nature of magnesium vanadates during the oxidative dehydrogenation of propane, magnesium pyro- and othro-vanadates (Mg_2V_2O_7 and Mg_3V_2O_8, respectively) used for the conversion of propane with and without gaseous oxygen were analyzed by XRD, solid state ^<51>V MAS NMR and XAFS. After the propane conversion without oxygen, complete conversion of those magnesium vanadates to the corresponding vanadate containing V^<4+> or V^<3+> species together with MgO was observed by XRD, while the reduction of V^<5+> was detected by ^<51>V MAS NMR and V K-edge XAFS from those catalysts. However XRD and ^<51>V MAS NMR revealed that re-oxidation of the reduced Mg_3V_2O_8 resulted in the regeneration of the original phase together with that of a V^<5+> species, while the re-oxidation of the reduced Mg_2V_2O_7 afforded a phase (triclinic system) different from the original one (monoclinic system), but, in which the V^<5+> species was regenerated from the reduced vanadium.
社団法人日本セラミックス協会の論文
2007-10-01