Preparation of catalyst precursors for selective oxidation of n-butane by exfoliation-reduction of VOPO4•2H2O in primary alcohol

A new method through intercalation and exfoliation of VOPO4.2H(2)O crystallites in primary alcohol (1-propanol or 1-butanol), followed by reduction with the alcohol, have been investigated for the preparation of catalyst precursor. Lamellar compounds, consisting of V4+, P5+ and alkyl group with thin film-like morphology, were formed and was characterized by means of XRD, IR, TG/DTA, and elemental analysis. The chemical formula of the precursor obtained by exfoliation-reduction in I-butanol was shown to be VO{(n-C4H9)(0.16)H-0.84}PO4.0.8H(2)O. On the other hand, a direct reduction of VOPO4.2H(2)O in the alcohol gave a mixed phase shown by (VOHPO4.0.5H(2)O)(0.3)(VO{(n-C4H9)(0.3)H-0.7}PO4.3H(2)O)(0.7) comprising plate-like microcrystallites. These precursors transformed to (VO)(2)P2O7 phase during an activation process at 703 K in the presence of a mixture of n-butane 1.5% and O-2 17% in He balance. The obtained (VO)(2)P2O7 through the exfoliation-reduction was well crystallized and consisted of thin flaky crystallites. It was found that (VO)(2)P2O7 thus prepared through the exfoliation-reduction was highly active and selective for oxidation of n-butane. (C) 2002 Elsevier Science B.V. All rights reserved.