Summary of study involving the use of hydrodesulfurization of diesel fuel with the industrial most commonly used catalyst - zeolite

1. CATALYST IN OIL AND GAS
INDUSTRY
CHUNG KEN VUI
A98753
KB/4
Zeolite in Hydrodesulphurization

2. ZEOLITES AS CATALYST
 Crystalline, hydrated,
microporous aluminosilicate
mineral
 Network of tetrahedral of
aluminate and silicate ions,
linked by sharing oxygen atoms
 Contains alkaline earth metals
and water trapped in the cavities
 High boiling point, largely
insoluble in water or inorganic
solvent, non-flammable and non-
oxidize in air
 Used vastly in petrochemical
processes:
 Fluid catalytic cracking
 Hydrodesulphurization
 Isomerization
Molecular structure of ZSM-5
Source: Clements et al. 2010

3. Structures of four selected zeolites (from top to bottom: faujasite or zeolites X,
Y; zeolite ZSM-12; zeolite ZSM-5 or silicalite-1; zeolite Theta-1 or ZSM-22) and
their micropore systems and dimensions
Source: Weitkamp 2000

4. HYDRODESULPHURIZATION (HDS)
• Desulfurization can be performed via two parallel pathways:
 Direct desulfurization pathway (DDS)
 Hydrogenization pathway (HYD)
• Compounds containing sulphur undergo a catalytic reaction
with hydrogen to form the corresponding hydrocarbon and
hydrogen sulphide (El Kady et al. 2010)
Two distinctive HDS process pathways of 4,6-dimethyldibenzothiophene
Source: Oyama et al. 2012

5. HYDRODESULPHURIZATION (HDS)
 HDS helps to eliminate sulphur to achieve desirable low-sulphur diesel
fuel
 Commercial HDS catalyst: Mo or W supported on γ-alumina, promoted
by either Co or Ni
1. El Kady et al. investigate the use of CoMo/γ-alumina on HDS
 The differences between equilibrium deposition filtration (EDF)
and incipient wetness impregnation (IWI)
Temperature
(°C)
kS (h-1) kA (h-1)
EDF IWI EDF IWI
340 2.480 2.050 0.874 0.570
360 3.230 2.500 1.180 0.777
380 3.800 3.190 1.360 1.000
400 4.500 4.180 1.280 0.860
Rate constants for HDS and hydrodearomatization (HAD) of HGO at various
reaction temperatures at P = 50 bar and LHSV = 1.5 h-1
Source: El Kady et al. 2010

6.  While alumina catalyst alone can demonstrate high activity for
hydrogenation, HDS and hydrodenitrogenation (HDN), the acidity
property is insufficient to promote hydrocracking and isomerisation.
2. Nakano et al. suggested the combination of USY-zeolite with γ-
alumina
 Physical mix of zeolite and γ-alumina may be unfavoured due to
over-cracking and coke formation
 Coating of alumina on zeolite particle
HYDRODESULPHURIZATION (HDS)
T (°C) CZ-1 CZ-5 AZ LX6
kS
(h-1)
S (ppm) kS
(h-1)
S (ppm) kS
(h-1)
S (ppm) kS
(h-1)
S (ppm)
330 25.8 113.3 17.4 228.3 24.7 122.0 14.9 300.5
345 71.0 16.7 46.9 37.0 63.8 20.5 37.9 55.4
360 144.0 4.2 94.9 9.5 131.8 5.0 93.4 9.8
Table 2 Performances of catalysts in dual-bed configuration for HDS of HGO at
different temperatures under operating conditions of P = 6 MPa and LHSV = 1.0 h-1
Source: Nakano et al. 2013