produces an additional feedstock apart from the crude unit, such as a delayed coking
unit, FCC unit, and the like. Oxygen and halides are not always present. The
hydrotreating reactions proceed in the following order: metal removal, olefin
saturation, sulfur removal, nitrogen removal, oxygen removal, halide removal,
Hydrotreating
Hydrocracking
Reaction Classes
Hydrocracking Reactions
Remove:
Sulfar
H 2
H 2
Reaction Classes
Hydrodesulfurization
Hydrodenitrogenation
Aromatics Saturation
PNA Formation
Paraffin Isomerization
Paraffin Cracking
Cyclization
Nitrogen
Oxygen
Halides
Metals
Saturate
Olefins
Aromatics
Polycyclic Aromatics
Fig. 8 Summary of hydroprocessing reaction classes in the sections of the hydrotreating and
hydrocracking reactors
Molecular Evolution in the Hydrotreating Reactor
Aromatics
Sulfur
Nitrogen
R2
R1
R2
R1
R2
R1
NH 2
N
N
NH
S-S
S
SH
S
S
S
S
N
NH
R1
R1
R2
R1
R2
R1
R2
R1
NH 3 H 2 S
NH 3 H 2 S
NH 3 H 2 S
Fig. 9 Evolution of the reactions in the hydrotreating reactor
332
M. Bricker et al.