Mossbauer emission studies of Co-Mo/Al/sub 2/O/sub 3/ hydrodesulfurization catalysts: effects of reduction and sulfidation treatments

The effect of the sulfiding temperature on the catalytic and structural properties of Co-Mo/Al/sub 2/O/sub 3/ catalysts is studied by taking into account the after-effects arising from 57-Co in the alumina. The catalytic activity is shown to be correlated to both MoS/sub 2/ or CoMoS and Co/sub 9/S/sub 8/ phases.Anglai

X-ray induced surface modification of aluminovanadate oxide

Aluminovanadate oxide, ‘‘V–Al–O’’, has been studied by X-ray photoelectron spectroscopy (XPS) with the emphasis to reveal chemical modifications as a function of the X-irradiation time. Considerable damage was found for V–Al–O and less so for vanadium pentoxide, V2O5, and sapphire, a-Al2O3, both serving as reference samples. Modifications in V–Al–O were seen even at low radiation doses. Absolute and relative shifts in binding energies along with changes of peak intensities and widths demonstrate that an appreciable amount of V5+ is reduced to lower oxidation states. X-ray induced chemical modifications extend at least to the depth sampled by the V3p electrons. It is suggested that the damage is caused by electron-hole pair generation and Auger decay. Al–O–H in V–Al–O is also affected by X-rays. This causes O2 and water desorption as followed by mass spectrometry of the residual gas.info:eu-repo/semantics/publishe