Chapter 7 Catalyst deactivation

Abstract

Publisher SummaryThis chapter describes catalyst deactivation in terms of the modifying effect of components of heavy feeds, as well as that of operating parameters on catalyst surface leading to the loss of activity. Among the latter, temperature, H2 pressure, and H2S/H2 ratio are the parameters that have pronounced effects on the structure of catalyst surface in relation to deactivation. The properties of catalysts influence deactivation patterns as well. The adverse effect may be further enhanced by the H2 pressure, provided a sufficient concentration of H2S is not maintained. In the case of heavy feeds, the deposition of coke and metals is the main reason for the loss of catalyst activity. For vacuum gas oil (VGO) feeds, catalyst deactivation is dominated by the poisoning, involving N-compounds and coke deposition. The contribution of metals to deactivation becomes evident beginning with deasphalted oil (DAO) and increases toward atmospheric residue (AR) and vacuum residue (VR). The relative contribution of coke and metals to catalyst deactivation depends on several factors, for example, the origin of feed, type of catalyst, operating conditions, type of reactor, and position of catalyst in the fixed bed.