ISSN:
1572-879X
Keywords:
Solid-state27Al NMR
;
cross-polarization
;
hydrotreating catalyst precursors
;
hydrated aluminum molybdates
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A previously unobserved octahedral27Al MAS NMR resonance has been detected in rehydrated calcined Mo/Al2O3 hydrotreating catalyst precursors. This resonance is attributed to the presence of hydrated forms of aluminum molybdate such as [Al(OH) n (H2O)6-n ] n (MoO4) (n = 1 or 2). The cross-polarization relaxation parameters, obtained from variable contact time experiments, yielded information on the relative sizes of the [Al(OH) n (H2O)6-n ] n (MoO4) domains in the catalysts with different molybdenum loadings. Analysis of the27A1 MAS NMR spectra of P-Mo(8)/Al2O3 and P-Mo(12)/Al2O3 (wt%P = 0.0–12.0) shows that a function of the phosphate in the 12 wt% Mo catalyst is to prevent the re-hydration of the molybdate phases on the calcined catalysts.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00771746
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