INCORPORATION OF IRON(III) AND CHROMIUM(III) IN SAPO-37

Incorporation of iron(III) and chromium(III) in the SAPO-37 framework was investigated. Pure faujasite structures were obtained using a mola r composition of 0.95 Al2O3:1.0 P2O5:0.50 SiO2:0.05 Me:1.0 (TPA)(2)O:0 .05 (TMA)(2)O:120 H2O (Me = Fe or Cr) in the synthesis gel and a cryst allization temperature of 180 degrees C. Iron replaces tetrahedrally c oordinated aluminum in the structure, whereas chromium is preferential ly coordinated to the oxygen atoms of the lattice, probably in structu ral defects, and only a minor amount is in an isomorphous position. A major part of the tetrapropylammonium ions, located in the supercages, can be exchanged by sodium ions in methanolic solution without a sign ificant loss of crystallinity of the samples. FeAPSO-37 and CrAPSO-37 are active catalysts in the liquid-phase oxidation of benzene and cycl ohexane. (C) Elsevier Science Inc. 1997.