1 research outputs found
On the role of triethylene glycol in the preparation of highly active Ni-Mo/Al2O3 hydrodesulfurization catalysts: A spectroscopic study
The interaction of triethylene glycol (TEG) with alumina and its role in preparing improved NiMo/Al2O3
hydrodesulfurization catalysts was investigated by spectroscopic methods. The FT-IR study shows that
TEG is mainly adsorbed on the corners and edges of the alumina microcrystals where the strongest
Lewis sites and the higher OH frequency hydroxyl groups are mainly located. It is also observed that
the Mo O stretching vibration of surface molybdenyl groups in the oxide catalyst precursor is shifted
down in the presence of TEG, indicating a lower interaction with the alumina surface. The IR spectra of
CO adsorbed on the reduced/sulfided NiMo/Al2O3 catalysts confirm that the amount of promoted phase
(NiMoS sites) increases in the samples prepared with TEG. Accordingly, the activity measurements in the
HDS of 4,6-dimethyldibenzothiophene show that the catalyst prepared with TEG is more active than the
one prepared without it. It is proposed that TEG and its decomposition products, formed upon heating
(mainly acetates) occupy preferably the strongly interacting edge and corner sites of the alumina crystals,
forcing the Mo and Ni species to migrate mainly to the less reactive plane faces. This weakens the metalsupport
interaction allowing a better sulfidation and, at the same time, favoring the Ni\u2013Mo interaction
and the formation of the promoted NiMoS phase