Effect of calcination/rehydration treatments on the environment of V in beta zeolite

A dealuminated zeolite beta has been contacted with solutions of ammonium m etavanadate to incorporate vanadium as tetrahedral V species which are not removed under treatment with aqueous solution of ammonium acetate. The effe cts of calcination and rehydration on the environment of the V species have been studied by diffuse reflectance UV-visible and V-51 NMR. The reducibil ity of the V species has been followed by TPR and ESR. The dehydroxylation/ rehydroxylation process occurring in the beta framework upon dehydration/re hydration has been monitored by Si-29 MAS NMR and FT-IR spectroscopy.