All sulfided NiMo/TNT(x) catalysts showed the presence of
well-dispersed MoS2 particles. However, some differences in the
morphology (slab length and stacking degree) were detected with
the change in the support’s sodium content (Table 3). A decrease in
the sodium content from 7.1 to 0.1 wt.% resulted in a decrease in
the average length of the catalytically active MoS2 particles from
3.7 to 2.3 nm and an increase in their average stacking degree from
1.1 to 1.6. The above changes produced a 1.5 times increase in the
fMo value (Table 3), representing the fraction of Mo atoms located
on the catalytically active surface of MoS2 crystallites. The above
increase in dispersion of the MoS2 phase with a decrease in the
TNT sodium content can explain an increase in the overall catalytic
activity. On the other hand, an increase in the hydrogenation ability
of the NiMo/TNT(x) catalysts with a decrease in the support’s
Na content can be related to the increasing stacking degree of
the MoS2 particles, leading to a less hampered planar adsorption
geometry of the reactants on multilayered MoS2. Therefore,
the changes in the morphological characteristics of the MoS2 active
phase with variation in the support’s sodium content can be partially
responsible for the HDS activity and selectivity trends of
the NiMo/TNT(x) catalysts.