用固体核磁共振研究Al/P>1的磷酸铝分子筛AlPO_4-5

Solid-state NMR Studies on AlPO_4-5 Molecular Sieve with Al/P>1

用固体高分辨核磁共振（NMR）方法对一系列Al／P＞1的新型磷酸铝分子筛AlPO4-5中磷和铝的结构状态及联结方式进行了研究，27Al和31PNMR都给出了在分子筛骨架中存在有Al－O－Al联结方式的实验证据，寓示着在该体系中P和Al的排布不再遵循Loewenstein规则．

Solid-state NMR spectroscopy was employed to investigate the coordination state of P and Al, as well as their linkages in a series of newly synthesized alunilnophosphate molecular sieye AlPO4-5 with Al/P>1. Both 31P and 27Al NMR provides evidence that Al-O-Al linkages are present in the framework of these molecular sieves, which implies that the ordering arrangement of P and Al does not obey the well-known Loewenstein rule. Apart from the usually observed NMR signals, a broad peak at ca. δ=10 is present in the 27Al MAS spectra of the calcined and dehydrated AlPO4-5 molecular sieves. Due to its large second-order quadrupole shift, an isotropic chendcal shift of ca. δ=38 was estimated. Hence, we attribute this signal to 4-coordinated alumin