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 molar 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 crystallization temperature of 180 degrees C. Iron replaces tetrahedrally coordinated aluminum in the structure, whereas chromium is preferentially coordinated to the oxygen atoms of the lattice, probably in structural 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 significant loss of crystallinity of the samples. FeAPSO-37 and CrAPSO-37 are active catalysts in the liquid-phase oxidation of benzene and cyclohexane. (C) Elsevier Science Inc. 1997.