Environmental Engineering Reference
In-Depth Information
Figure 7.9: Structures of organic agents used for catalyst rejuvenation.
chelating agents on the activity of regenerated catalysts were evident after sulfidation. This
method is discussed in the section on Reactivation.
7.1.1 Mechanism of Rejuvenation by Organic Agents
Ability of an organic agent to form a complex and/or a compound with contaminant metal ions
either in solution or in contact with a solid is an essential requirement to be an efficient
rejuvenation agent. The overwhelming information confirmed that this requirement is best
fulfilled by di-carboxylic acids (e.g., oxalic, citric, tartaric, etc.), while monocarboxylic acid
are less efficient, though more efficient than aldehydes and ketones. The structures of some
organic agents are shown in
Fig. 7.9
. The dissociation of an acid to anion and hydronium ion
precedes the formation of a complex with a metal in solution. For oxalic acid, this can be
depicted as follow:
{
7.1
}
