Synthesis and structural characterization of AlPO4-18 and Magnesium and Zinc substituted AlPO4-18

Abstract

AlPO4-18, MgAlPO4-18 and ZnAlPO4-18 have been synthesized by using N, N-diisopropyl ethylamine as the structure directing agent. The powder XRD data of the metal substituted samples show significant changes in the patterns as an effect of metal loading. The metal loaded samples show broader peaks (smaller crystallite size) and lower crystallinity as compared to the AlPO4-18. Indexing the powder patterns revealed that AEI sample has the space group C2/c. The MAPO-18 samples showed lowering of symmetry with a change in the space group to P21. An increase in the lattice parameters of the Zn and Mg substituted samples is observed which indicates isomorphous substitution of metals in the aluminophosphate framework. The solid state 27Al NMR data confirmed substitution of the metal atoms in the Al site, preferentially at the Al-1 site. The 31P NMR data indicate formation of one more crystallographically different P atom as an effect of metal loading.