Hydroprocessing of Petroleum - Spent Hydroprocessing Catalysts - page 30

Figure 3.3: Effect of feed origin on loss of surface area and porosity of catalysts. A. Kuwait
atmospheric residues (AR). B. Boscan feed [From ref. 89 . Reprinted with permission].
be established to achieve a high catalyst performance. This would suggest that the feed was not
heavy enough to observe the importance of macroporosity.
The above discussion suggests that there is an optimal combination of the surface area and
porosity giving the highest catalyst activity [88] . The optimum may be different for different
feeds and catalysts. This is evident from the results in Fig. 3.3 [89] showing the effect of feed
origin on the loss of porosity and surface area of catalysts. Naturally, one would expect such
effects when the properties of the relatively light Kuwait residue are compared with the Boscan
feed. However, the optimal combination of surface area and pore size distribution was also
crucial for achieving a high activity during the HDS of several gas oil of variable boiling range
[77] . Another example of the effect of the feed origin is shown in Fig. 3.4 [90] . In this case, for
HGO, the steady catalyst performance was maintained for an extended period, whereas a
continuous catalyst deactivation was observed during hydroprocessing of the atmospheric
residue. For the latter, the catalyst was deactivated both by coke and metal deposits.