as a standalone is able to achieve 104.9% of volume swell compared to 104.6% for its fresh while reach- ing the 10 ppmwt product sulphur range. The stacked bed configura - tion loaded with 70% fresh NiMo and 30% Excel CoMo exhibits the lower volume swell, namely 104.1% for the 10 ppmwt product sulphur range. This can be easily explained by the fact that CoMo catalysts are typically less active for HDN and aromatic saturation than NiMo catalysts. The term volume swell refers to the increase of liquid volume when the product density and boiling range are lowered by hydrotreating. This is induced by different reac - tions, such as HDS and HDN, but, more importantly, the saturation of poly-aromatics and mono-aromat- ics. In Figure 6 , the volume swell has been quantified by comparing the liquid product density with the feed density. As per Figure 7 , Excel rejuvenated catalyst and its stacked options exhibited a similar C 5 + yield compared to fresh for the 10 ppmwt product sulphur range. Hydrogen consumption Figure 8 shows hydrogen con- sumption and compares Excel or stacked configurations with fresh. Excel rejuvenated NiMo as a stan- dalone exhibited better hydro - genation activities (HDS, HDN, and HDA activities) than its parent fresh, leading to a slightly higher hydrogen consumption. Excel reju- venated NiMo catalyst as a stan- dalone achieved about 1000 scf/bbl (or 178 Nm 3 /m 3 ), whereas its par- ent fresh consumed about 900 scf/ bbl (or 160 Nm³/m³), corresponding to an increase of 10.1% in terms of hydrogen consumption. Experience has shown that stacked beds con- taining both CoMo and NiMo cat- alysts can be designed to provide high HDS performance while mini- mising hydrogen consumption. For instance, the stacked bed configu - ration, including 70% rejuvenated NiMo and 30% rejuvenated CoMo, is able to reduce hydrogen con- sumption by 50 scf/bbl (or 9 Nm³/ m³) while maintaining equal prod- uct sulphur concentration compared with 100% rejuvenated catalyst.
40
Feed Fresh NiMo Excel NiMo
30
30% Excel NiMo / 70% Fresh NiMo 70% Fresh NiMo / 30% Excel CoMo 70% Excel NiMo / 30% Excel CoMo
20
10
0
Mono-aromatics
Di-aromatics
Tri+-aromatics
Figure 4 Aromatics content in feed and products for condition 6
mono-aromatics content compared to fresh as a standalone and, there- fore, a similar volume swell. Both stacked bed Excel CoMo versions loaded with either Excel NiMo or fresh resulted in slightly lower mono-aromatics content. This can be explained by the fact that CoMo catalysts provided lower HDN and aromatic saturation compared to NiMo catalysts. Figure 6 shows volume swell efficiencies and compares Excel or stacked configurations to fresh cat - alyst. Excel rejuvenated catalyst
10 ppmwt product sulphur range. For condition 9, mono-aromatics are saturated the most, resulting in more volume swell and lower residual content of mono-aromat- ics. Excel rejuvenated catalyst as a standalone has even showed enhanced performance in terms of aromatic saturation in compar- ison with its parent fresh, since it exhibited 30 wt% as mono-aromat- ics compared to 31.9 wt%. It can be noticed that the stacked bed ver- sions loading with Excel NiMo and fresh catalysts exhibited similar
40
Feed Fresh NiMo Excel NiMo
30
30% Excel NiMo / 70% Fresh NiMo 70% Fresh NiMo / 30% Excel CoMo 70% Excel NiMo / 30% Excel CoMo
20
10
0
Mono-aromatics
Di-aromatics
Tri+-aromatics
Figure 5 Aromatics content in feed and products for condition 9
52 PTQQ 2 2022
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