Mössbauer spectroscopic study of iron phosphate catalysts used in selective oxidation
Abstract
Three iron phosphate compounds FePO4, Fe2P2O7 and Fe7(PO4)6 have been synthesized and studied as catalysts for the oxidative dehydrogenation of isobutyric acid to methacrylic acid. Mössbauer spectroscopic characterization of the solids before and after catalytic reaction has allowed us to show that the starting phases were transformed in the conditions of reaction and that a new phase was formed. This new phase is a mixed Fe3+ and Fe2+ phosphate with a Fe3+/Fe2+ ratio of 1.8±0.2 with Mössbauer parameters: δ1=0.47 ± 0.05, Δ1=0.68± 0.02 mm.s-1 and δ2=1.20 ± 0.05, Δ2=2.73±0.02 mm.s-1. This new phase appears to be elective for methacrylic acid formation.
- Publication:
-
Hyperfine Interactions
- Pub Date:
- March 1989
- DOI:
- 10.1007/BF02398251
- Bibcode:
- 1989HyInt..46..619M
- Keywords:
-
- Oxidation;
- Iron;
- Phosphate;
- Thin Film;
- Acid Formation