Environmental Engineering Reference
In-Depth Information
7.5 Non-Leaching Methods for Contaminant Metals Removal
Hettinger
[510]
concluded that there is a potential of the magnetic separation method for
removing contaminant metals, such as V, Ni, and Fe from spent cracking catalysts. Similarly,
this technique may be applied to hydroprocessing catalysts, although so far no experimental
results could be found in the literature.
A well-established fact that contaminant metals accumulate predominantly on the external
surfaces of catalyst particles (
Figs 7.11 and 7.19
) suggests that abrasion/attrition method may
be suitable for rejuvenation of spent catalysts. A reference to this method was made by Trimm
[345]
in his review article. Assuming that abrasion/attrition removes the outermost layers of
the catalyst particles, the attrited material should have a high content of V and Fe. However,
the removal of metals from pores would require a prolonged attrition. It is not certain whether
the strength of catalyst particles can be maintained under such conditions. Apparently, this
method may have only limited applications in rejuvenation of spent hydroprocessing catalysts.
It is believed that this method is more suitable for rejuvenation of the spent fluid catalytic
cracking (FCC) catalysts.
