Results from the catalytic activity evaluation and from the
HRTEM characterization of the sulfided NiMo/TNT(x) catalysts
(fMo) were used to calculate the TOF values shown in Table 3.
These values represent a number of DBT molecules reacted per second
per Mo atom located on the catalytically active surface of MoS2
crystallites. The TOF values obtained for the NiMo/TNT(x) catalysts
with different sodium content varied between 1.0 103 and
1.5 103 s1 (Table 3). In general, the TOF values obtained in the present work are similar to those reported by us previously for
HDS of dibenzothiophene over NiMo catalysts supported on
SBA-15 [40] and other materials (SBA-15, ZrSBA-15, ZrO2, and
c-Al2O3) without sodium [42]. However, in the present work a relationship
was observed between the TOF value and the support’s Na
content. This is probably because in the presence of NiMo catalysts
the elimination of the sulfur atom from the DBT molecule occurs
quicker through the HYD pathway than through the DDS route,
or because of the abovementioned increase in the amount and
mobility of spillover hydrogen with decreasing sodium content in
the support.