Environmental Engineering Reference
In-Depth Information
Figure 3.7: Effect of particle shape and relative volume activity on reactor pressure drop
[From ref. 91 . Reprinted with permission].
Remarkable improvements have been made in recent years in the performance of catalysts
used in distillate and residual oil hydroprocessing units [27,92-95] . Development of improved
hydrotreating catalysts has been possible through a clear understanding of the key properties,
namely, nature of the active sites and their structure, and the textural characteristics of
supports, more specifically pore size, that have significant influence on the catalysts
performance [53,96-102] . The scientific basis for the high activity of the new generation
hydrotreating catalysts have been presented in many reviews and in some recent papers
[53,102-108] . Haldor Topsoe has introduced a number of catalysts, such as TK-573, TK-574,
TK-911, and TK-915, which not only significantly improved HDS activity, but also tackled
density and aromatics reduction.
Recently, Topsoe et al. [108,109] have developed a new catalyst preparation technology, giving
highly active hydroprocessing catalysts. This new proprietary BRIM technology not only
optimizes the brim site HYD functionally, but also increases the type II activity sites for direct
desulfurization [109] . The first two commercial catalysts based on the brim technology were
Topsoe's TK u 558 BRIM (CoMo) and TK u 559 BRIM (NiMo) for FCC pretreatment service.
This was followed by a new series of high performance TK u 576 BRIM (CoMo), TK u 575
BRIM (NiMo) and TK u 605 BRIM catalysts for ultra low sulfur diesel production and for
hydrocracker feed pretreatment. Akzo Nobel (now Albemarle) came up with the STARS (KF
757, KF 767, KF 848, etc.) catalysts series [110,111] , which almost doubled the HDS activity.
More recently, the company started to market a new catalyst, the NEBULA, which is
considered a breakthrough in hydrotreating catalysis [93] . The new catalyst is almost four
times as active as the conventional CoMo/Al 2 O 3 catalyst as used for the hydroprocessing of
gas oil [113] . This is indicated in Fig. 3.8 [114] by a significantly decreased weight average
 
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