Characterization of the sulfided NiMo/TNT(x) catalysts by FT-IR
spectroscopy of CO adsorbed at low temperature (173 C)
showed that in addition to the changes in the morphology of the MoS2 particles, the number of CUS sites and their acid strength
were also strongly affected by the content of sodium in the samples
(Fig. 7). Thus, sulfided NiMo/TNT(7.1) and NiMo/TNT(3.2) catalysts
showed the presence of well-promoted MoS2 phases with a
large number of CUS sites; the NiMo/TNT(0.1) catalyst contains
mainly a fully sulfided NiMoS phase with a small number of S
vacancies. In addition, the NiMo/TNT(7.1) sample had a lower acid
strength of the vacant sites than other catalysts with lower Na
loading, which was attributed to electron donation by sodium
leading to an increase in the electronic density on the Mo atoms.
According to work, the acid strength of the CO adsorption sites
is related to the hydrogenation activity of the catalyst, increasing
with the acidity of the support and decreasing with the increase
in the basicity. Therefore, the change in the acid strength of the catalytic
sites with the support’s sodium content can be another reason
for the modification of the hydrogenation/hydrogenolysis
abilities of the NiMo/TNT(x) catalysts.