Effects of the support in Fe2O3-MoO3/Al2O3 catalysts

Abstract Diffuse reflectance, ESR and Mossbauer measurements were carried out on Fe 2 O 3 and Fe 2 O 3 · 4(MoO 3 ) supported on α- and γ-alumina before and after their interaction with methanol. These data were compared with the catalytic behaviour in the oxidation of methanol to formaldehyde in a fluidized bed reactor. For α-Al 2 O 3 -supported catalysts, Fe 2 (MoO 4 ) 3 and Fe(III) dissolved within the lattice were detected. Also for γ-Al 2 O 3 -supported catalysts, two Fe(III)-containing compounds were found, namely, Fe(III) dissolved within the carrier and another FeMo-containing compound which was considered to be either a surface Fe-Mo bilayer or a surface FeAlMo heteromolybdate. This latter compound is active only in dimethyl ether formation.