II International Symposium on Carbon for Catalysis ABSTRACTS

OP-I-22
AS in the catalysts examined are identical and that the support has an effect only on their
concentration.
Comparing of Al 2 O 3 modification by P- and F-addtives
The investigation of Al 2 O 3 modification by P- and F-additives has shown that the
introduction of the additives leads to the formation of new reduced sites (so-called “empty
sites” - ES). The correlation between the growth of the support acidity and the number of the
ES has been established. Modification effects by P and F are different: P-modification of
Al 2 O 3 -support does not change the AS productivities of the AS related to Mo- and Co-sites
but changes their ratio. F-modification leads to AS productivity decrease. F-adding results in
decrease of both the number of the AS in CoMoS phase and their productivities. F affects the
sites belonging to Co to a greater extent than the sites belonging to Mo.
Modifying of the Al 2 O 3 by P or F results in changes of the nature of the active sites
responsible for hydrodesulfurization and in the formation of new “empty sites” (ES)
facilitating hydrogenation of aromatics.
Conclusions
1. The C-supported catalysts contain more mobile sulfur than the Al 2 O 3 -supported catalysts
because of the smaller particle size of the active phase.
2. The nature of the support and the amount of active phase do not affect the reactivity of
the active sites but affect their number. The dynamic properties of the active sites in the
NiMo and CoMo catalyst are similar.
4. The hydrogenation of butenes that have resulted from thiophene hydrogenolysis takes
place on sites that are associated with Mo and responsible for desulfurization.
5. Replacement of Al 2 O 3 by activated carbon in supported catalysts leads to enlarging of the
number of the active sites without any changes in their nature whereas modifying of
Al 2 O 3 by P- or F-additives may result in changes of the nature of the active sites and in
formation of new sites.
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