Reactivity of MoO3: effect of molybdenum with Al2O3 precursor and the presence of water vapour on the dispersion of the surface phases

摘要

MoO3/Al2O3 systems have been prepared by calcining at 770 K alumina impregnated with ammonium heptamolybdate (aq), or by calcining molybdena/alumina mixtures at 770 K. Surface polymolybdates have been observed by laser Raman spectroscopy in samples prepared by impregnation: for calcined MoO3/Al2O3 mixtures, X-ray diffraction indicates MoO3 readily spreading over the alumina surface in the presence of water vapour, and this being almost complete after calcination for 2 h. © 1992 Chapman & Hall.