Structural investigation by multinuclear solid state NMR and X-ray diffraction of as-synthesized, dehydrated, and calcined AlPO4-SOD

AlPO4-SOD, a microporous aluminophosphate, was synthesized in a quasi-nonaq ueous medium using dimethylformamide as solvent and template. The as-synthe sized, dehydrated, calcined materials and the corresponding rehydrated phas es were investigated by various solid-state nuclear magnetic resonance (NMR ) and powder X-ray diffraction techniques. Structural data from the NMR stu dy are in a very good agreement with the as-synthesized AlPO4-SOD structure refined from powder synchrotron data. P-31 homonuclear correlation and P-3 1/Al-27 3QHETCOR experiments allowed the complete assignment of P-31 and (2 1)AI resonances to the corresponding crystallographic sites. P-31 and Al-27 NMR spectra are drastically modified after dehydration at 200 degreesC and calcination at 800 degreesC. A possible structural rearrangement of the te mplate molecules is proposed that explains NMR and XRD data of the dehydrat ed material. The structure of the calcined material solved by powder XRD is in agreement with the NMR data.