Synthesis, characterization and structure of SAPO-56, a member of the ABC double-six-ring family of materials with stacking sequence AABBCCBB

✍ Scribed by Steve T Wilson; Robert W Broach; C.Scott Blackwell; Charles A Bateman; Nancy K McGuire; Richard M Kirchner

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 526 KB
• Volume: 28
• Category: Article
• ISSN: 1387-1811
• DOI: 10.1016/s1387-1811(98)00293-5

✦ Synopsis

SAPO-56, a silicon-containing aluminum phosphate molecular sieve, is characterized by electron microscopy, magicangle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and Rietveld refinement of synchrotron X-ray powder diffraction data. The trigonal space group is P3 :1c with a=b=13.7571(3) A ˚, c=19.9362(7) A ˚, a=b= 90°and c=120°. This member of the ABC six-ring-structure family contains double six-rings arranged to give gmelinite (gme) cages and another large cage (aft), which has only been observed before in AlPO-52. The stacking sequence of six-rings in SAPO-56 is AABBCCBB. This unique topology has been assigned structure-type code AFX. Analysis of X-ray peak widths reveals broadening due to slight faulting and silicon disorder. 29Si-NMR results indicate that the silicon is distributed between isolated framework T d sites, silicon islands and silica debris.