Environmental Engineering Reference
In-Depth Information
demonstrate that neither controlled regeneration in 2% O
2
nor that in air could ensure an
acceptable activity recovery in spite of the fact that the HDS and HYD activities were
determined using small molecules, such as thiophene and cyclohexene, respectively. It is
believed that if a heavy feed (comprising much larger size molecules) would be used for the
activity determination, the difference would be even more evident. It is, however, believed that
in a pulverized form, such solids could still be suitable catalysts for hydroprocessing of heavy
feeds conducted in the slurry bed reactors.
The effect of the amount of deposited metals (V+Ni) on catalyst activity was investigated by
Clark et al.
[414]
. The coke in spent catalysts was removed by oxidative burn-off. The results
in
Fig. 6.23
show that the activity of the decoked catalyst containing about 8 wt.% of the
Figure 6.23: Ramsbottom carbon (RBC) conversion and hydrodenitrogenation (HDN) activities
of fresh and decoked catalysts [From ref.
414
. Reprinted with permission].
