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Bull. SOC. Chin. Belg. vo1.96/n0 11-12/1987
0037-9646/87/ $ 2.00 + 0.00
8 1987 C d t 6 van Behser van hst Bulletin V.L.Y.
THIRD WORKSHOP MEETING ON HYDROTBEATINC CATALYSTS
Louvain-lo-Neuve, 16
18 November, 1987
-
COMPARATIVE
HYDRODESUIXURIZATION OF
OVER
Ni-Mo
AND
ATHABASCA O I L SANDS
CO-Mo
CATALYSTS
COKER
GAS
OIL
Z a c h a r i a Wathew George and P e t e r Mohammed
5 t h S t r e e t , Nisku, A l b e r t a , TOC ZGO, CANADA
A l b e r t a Research C o u n c i l , 1 9 0 1
-
ARC C o n t r i b u t i o n No.
1479
ABSTRACT
The h y d r o d e s u l f u r i z a t i o n of AthabASCa o i l s a n d s c o k e r g a s o i l h a s been
comgared over N i - M o and Co-Mo c a t a l y s t s on t h e b a s i s of r a t e c o n s t a n t s a t
400 C, 10. 3 ma (H ) and a t a n LHSV o f 1 2 . 0 h - l .
Both c a t a l y s t s were c y l i n d r i cal e x t r u d a t e s o f 3 . 5 mm x 1.6 mm. A B e r t y Continuous S t i r r e d Tank Reactor
(CSTR) uaa uaed f o r t h e h y d r o p r o c e s s i n g . Although t h e N i - M o c a t a l y s t had higher a c t i v i t y per gram of c a t a l y s t , on t h e b a s i s of t h e r a t e w n s t a n t p e r gram
o f molybdenum, t h e Co-Mo c a t a l y s t w a s s l i g h t l y more a c t i v e w i t h lower a c t i v a t i o n energy t h a n t h e N i - M o c a t a l y s t f o r HDS.
INTRODUCTION
Athabaaca o i l s a n d s bitumen, which c o n t a i n s a p p r o x i m a t e l y 5 w t % a u l f u r
and 15-20 w t % a s p h a l t e n e s and o v e r 50 0 p i t c h ( f r a c t i o n d i s t i l l i n g above
525OC) is s e p a r a t e d from the o i l s a n d s by C l a r k ' s h o t w a t e r p r o c e s s (1) and
upgraded t o s y n t h e t i c c r u d e by t h e r m a l c r a c k i n g ( c o k i n g ) . Two cornmarcia1 o i l
s a n d s p l a n t s are i n o p e r a t i o n i n A l b e r t a w i t h a combined p r o d u c t i o n of o v e r
250,000 b a r r e l s of s y n t h e t i c c r u d e p e r day.
A t t h e Suncor p l a n t a t F o r t
McMurray, A l b e r t a , t h e primary upgrading is accomplished by d e l a y e d c o k i n g
which i s a b a t c h o p e r a t i o n . A t t h e Syncrude Canada Ltd. p l a n t a t Mildred Lake,
A l b e r t a , f l u i d coking ( c o n t i n u o u s ) is employed.
The c o k e r g a s o i l c o n t a i n s a b o u t 4.5 w t 0 s u l f u r and must b e reduced t o
l e s a t h a n 0.1 w t 0 t o meet s y n t h e t i c c r u d e r p e c i f i c a t i o n s . T h i s i s accompliahed by a h i g h t e m p e r a t u r e and h i g h p r e s s u r e h y d r o g e n a t i o n ( h y d r o p r o c e s a i n g )
o v e r a n e f f i c i e n t c a t a l y s t . The c a t a l y s t s ' u s e d i n t h e h y d r o p r o c e s s i n g o f t h e
c o k e r g a s o i l are N i - M o or Co-Mo c a t a l y s t s s u p p o r t e d on gamma alumina.
I t is
g e n e r a l l y a c c e p t e d t h a t N i - M o i s a n e f f i c i e n t HDN c a t a l y s t and t h a t Co-Mo i s
a n a t t r a c t i v e HDS c a t a l y s t f o r t h e c o k e r g a s o i l . The p r e r e q u i s i t e s f o r a n
e f f i c i e n t h y d r o p r o c e s s i n g c a t a l y s t s are a c i d i c and h y d r o g e n a t i o n f u n c t i o n s ,
e f f e c t i v e s u r f a c e a r e a , an e f f i c i e n t pore volume and pore size d i s t r i b u t i o n .
The a c i d i t y i s d e r i v e d from the s u p p o r t (alumina) and t h e h y d r o g e n a t i o n sites
o r i g i n a t e i n t h e metal a u l f i d e a .
I n a d d i t i o n , t h e m e t a l s must be f i n e l y d i s peraed o v e r the s u p p o r t . The commercial c a t a l y s t s are e x p e n s i v e , c o s t i n g as
much a s $ 15.OO/kg depending p r i m a r i l y upon t h e m e t a l l o a d i n g s .
One of t h e major reactions o c c u r r i n g d u r i n g h y d r o p r o c e s s i n g i s t h e rupt u r e of t h e c a r b o n - s u l f u r bond of t h e o r g a n i c molecules.
The c o k e r g a s oil
c o n t a i n s a m i x t u r e of a u l f u r compounds and it is g e n e r a l l y r e c o g n i z e d t h a t t h e
ease o f HDS i s dependent upon the t y p e o f s u l f u r compound, and the lower b o i l i n g f r a c t i o n s are d e s u l f u r i z e d more e a s i l y t h a n t h e h i g h e r b o i l i n g f r a c t i o n s .
A s c a n b e s e e n i n T a b l e s 1 a n d 3, t h e s u l f u r d i s t r i b u t i o n i n t h e c o k e r g a s o i l f r a c -
-
045
-
t i o n s do n o t v a r y t h a t s i g n i f i c a n t l y compared t o the n i t r o g e n . HDS r e a c t i o n
m y involve l a r g e consumption o f hydrogen; f o r example, t h e HDS o f t h i o p h e n e
nuy require 4 moles of hydrogen f o r a mole of HIS :
TABLE 1
Properties of Syncrude Coker Gas Oil
D e n s i t y a t 23'C
Sulfur content
Nitrogen content
Naphtha f r a c t i o n (b.p. < 1 7 7 O C )
L i g h t G a s Oil (b.p. 177 t o 343'C)
= 0.9830 g/cm
4.31 w t 9
0.31 w t 0
= Nil
25.4 w t 9
= 74.6 w t 0
370
31 e
--
Heavy G a s Oil ( b . p . >343'C)
Average molecular weight
Aromatic c o n t e n t
3
13c NMR
The o b j e c t i v e of t h i s i n v e s t i g a t i o n was t o e v a l u a t e t h e comparative HDS
a c t i v i t i e m o f Co-Mo and N i - M o c a t ~ l y s t mf o r h y d r o p r o c e s s i n g coker gas o i l u s i n g
a l a b o r a t o r y c o n t i n u o u s s t i r r e d t a n k r e a c t o r (CSTR)
.
EXPERIMENTAL
Materials
- SbalY.21
These are commercial e x t r u d a t e s of Co-n0 and N i - M o c a t a l y s t s s u p p o r t e d on grmma
alumina. T h e i r p r o p e r t i e s are summarized i n T a b l e 2 and FIG. 1. Both catal y s t r were c y l i n d r i c a l e x t r u d a t e s o f nominal 3.5 nun l e n g t h and 1.6 m d i a m e t e r .
TABLE 2
Composition and P r o p e r t i e s of Extruded C a t a l y s t s 3.5 nun (1) x 1.6
Composition ( w t 0 )
A1203
I
COO
1
N 10
co-Mo
Ni-HO
82.1
15.0
66.2
27.0
-
2.9
-
Proper ties
S u r f a c e Area
151
6.7
220
(m2 g-')
Pore V o l u m e
( m l . g-')
0.48
-
046
-
0.39
mm ( d )
FIG. 1.
*
P o r e V o l u m e D i s t r i b u t i o n f o r Ni-MD and
co-MOc a t a l y s t s .
co~er~ca~~oALlsccol
~~~
T h i s was o b t a i n e d by t h e f l u i d coking o f Athabasca o i l s a n d s bitumen by SynI t s p r o p e r t i e s are summarized i n T a b l e s 1, 3 and 4 .
c r u d e Canada Ltd.
%?GY -ISST1-R%!cloLAs5!embl_Y
The reactor assembly wao purchased from Autoclave E n g i n e e r s , E r i e , P e n n s y l v a n i a ,
T h i s is ahown i n FIG. 2 and c o n s i s t s of :
USA.
Syncrude Coker G a s O i l W a s mounted on a b a l a n c e and
a m e t e r i n g pump [Milton Roy Diaphragm Pump Model 5K
High p r e s s u r e hydrogen was i n t r o d u c e d (1.50
g/h)j.
of t h e reactor. The f e e d wao t h o r o u g h l y mixed by a
r e d t h e c a t a l y t i c reactor from t h e bottom.
pumped i n t o t h e reactor by
H 5MG, ( r a n g e 2 5 . 0 t o 2 5 0 . 0
&in
STP) a t t h e bottom
Magnadrive b e f o r e it e n t e -
G e n e r a l l y 8 . 0 g o f t h e c a t a l y s t was
The a u t o c l a v e had a volume of 6 1 2 m l .
sandwiched between two l a y e r s o f alumina s u p p o r t i n s i d e t h e c a t a l y s t b a s k e t .
Above the b a s k e t i s p l a c e d a c y l i n d r i c a l s t a i n l e s s steel p l u g w i t h a double
concave cross s e c t i o n on i t s bottom f a c e , FIG. 3 . T h i s i n s e r t s e r v e s t w o functions.
F i r s t l y , i t f i l l s up space w i t h i n t h e r e a c t o r and r e d u c e s h o l d up volu-
FIG. 2.
Berty (CSTR) Assembly.
-
847
-
TABLE 3
S p i n n i n g Band D i m t i l l a t i o n "
(SCGO)
B.P. Range
of cut, O C
-
Avg. B.P.
of c u t ,
Nitrogen Content
S u l f u r Content
Wt
OC
wt e
wt e
0.047
~250
(250
3.80
3.00
250-300
275
8.79
3.80
0.095
300-350
325
16.16
3.86
0.122
350-400
375
21.45
4.30
0.223
400-450
425
20.11
4.38
0.326
>450
>450
29.69
4.88
0.480
TABLE 4
Elemental A n a l y s i s of Syncrude Coker Gas O i l "
I
Element
Saturate.
Aromatics
( w t 8)
Polar I
P o l a r 11
p o l a t 111
C
05.56
84.63
83.93
03.65
79.35
H
13.65
10.56
7.94
7.92
8.50
0
0.61
0.78
1.21
0.72
5.53
N
0.08
0.04
0.01
0.40
2.21
S
0.10
3.99
6.91
7.23
4.41
FIG.
3.
C o n f i g u r a t i o n of B e r t y Reactor.
-
040
-
I
m e (100 m l ) ; necondly i t n n p e c i a l l y deaigned f a c e r e d i r e c t s t h e r e a c t a n t s
through the c a t a l y n t bed. Theme unique d e s i g n feature. t o g e t h e r w i t h h i g h
mixing n p e d (1000 rpm) ennure e f f i c i e n t i n t e r n a l r e c i r c u l a t i o n r e s u l t i n g i n
a CSTR o p e r a t i o n . The r a a a t o r in equipped w i t h automatic pranaure reducing
valvon. Liquid sample can be c o l l e c t e d i n t h e accumulator d u r i n g the r e a c t i o n
or can be nunpled continuously. The equipment is provided w i t h s a f e t y f e a t u r e s
t h a t i n c l u d e automatic equipment a h u t down i f t h e temperature o r p r e a s u r e exceedn a p r e n e t l i m i t or the metering pump h a s been blocked.
Typical Experiment
The reactor is heated to the r e a c t i o n temperature and simultaneously t h e
feed (SCGO and H2) i a t u r n e d on. General o p e r a t i n g c o n d i t i o n s were :
A
H 2 Prennure :
Temperature :
H2 Feed Rate I
LHSP :
Magnadrive :
Catalyat :
10.3 MPa
35O-41O0C
1.5 1 (STP)/min
12.0, h-l
1000 rpm
8.0 g, c y l i n d r i c a l e x t r u d a t e s
Analytical
ax up as
A f t e r t : nteadv a t a t e c o n d i t i o n s w e r e a t t a i n e d (-6 h r s fmm
v e r i f i e d by product a e n n i t y and s u l f u r c o n t e n t as a f u n c t i o n of t i m e on stream),
l i q u i d product sample i a c o l l e c t e d f o r 2-4 h r s i n t h e accumulator and analyzed
f o r a u l f u r (Leco SC-32). Helium wan bubbled through t h e l i q u i d sample t o remove diaaolved ganen. Trace q u a n t i t i e n o f a u l f u r are determined by Dorhman
a n a l y z e r . A t t h e end of t h e o p e r a t i o n ( a f t e r c o o l i n g o v e r n i g h t ) a sample of
t h e l i q u i d product from t h e hold up volume w a n a l s o analyzed. Generally, t h e
s t e a d y n t a t e nample a n a l y s i s was close t o t h a t from t h e hold-up volume in t e r m n
of d e n s i t y and s u l f u r c o n t e n t . Gas aamples were analyzed d u r i n g t h e experiment
f o r H 2 , hydrocarbons (Cl-C6) and HIS on a c a l i b r a t e d Thermal Conductivity detector.
C a t a l y s t a c t i v a t i o n ( h e a t i n g i n a flow of n i t r o g e n t o 4OOOC o v e r n i g h t ) and
p r e n u l f i d a t i o n of t h e c a t a l y n t w i t h hydrogen c o n t a i n i n g 10 v o l 0 H S d i d not
have b e n e f i c i a l e f f e c t . under our experimental c o n d i t i o n s . I t i a l i k e l y t h a t
t h e p a r t i a l p r e s s u r e o f H2S was s u f f i c i e n t l y high d u r i n g t h e hydroprocessing
such t h a t t h e working c a t a l y s t ramainn i n t h e e u l f i d e d s t a t e .
CSTR o p e r a t i o n of t h e Berty r e a c t o r wan i n v e s t i g a t e d by pumping g a s oil
c o n t a i n i n g 5.0 v o l 8 benzene i n the gan oil over t h e c a t a l y s t a t r o o m temperature and a n a l y z i n g f o r benzene i n t h e "product" stream a s a f u n c t i o n of t i m e .
I n a d d i t i o n t h e e f f e c t . o f mixing apeed, of hydrogen p r e s s u r e , of LHSV and t h e
e x t e n t of homogeneous r e a c t i o n on HDS were e v a l u a t e d .
RESULTS AND DISCUSSION
n i x i n g Speed
HDS a c t i v i t y increaned with mixing speed ( 4 O O O C and 10.3 HPa H2) and lev e l l e d o f f a t 1000 rpm. Consequently, t h e magnadrive wan set a t t h i a npeed.
Extent of Homogeneous Reaction
S i n c e the measured rate o f the c a t a l y t i c r e a c t i o n w i l l have c o n t r i b u t i o n n
from t h e a t a i n l e n s a t e e l n u r f a c e as w e l l a s from t h e alumina s u p p o r t (30 g f o r
most e x p e r i m e n t s ) , w e have i n v e s t i g a t e d t h e e x t e n t of HDS under t h e following
experimental condition. :
Temp. : 400°C
P ( H 2 ) : 10.3 MPa
F e e d r a t e : 0.5 g/min
-
049
-
These experiments ahowed t h a t a t an LHSV of 4 . 1 h'l, the moaaured HDS was
Under t h e a a m c o n d i t i o n s , the homogeneous r e a c t i o n amounted t o 3.0 0 .
92.7 0.
Ra8idence T h e D i s t r i b u t i o n
CSTR o p e r a t i o n was achieved i n about 4 . 5 hours a t room temperature.
Although i t is d e s i r a b l e t o confirm CSTR o p e r a t i o n under t h e hydroprocessing cond i t i o n s I ~ 4 O O 0 C , 1 0 . 3 MPa ( H Z ) , LHSV of 12.0 h'll due to t h e high conversion
l e v e l r , marker c o n c e n t r a t i o n i n t h e product stream w i l l be d i f f i c u l t t o i n t e r p r e t . Product q u a l i t y ( d e n s i t y and s u l f u r ) determined up to 16 hours showed
t h a t a f t e r 6 hours of o p e r a t i o n , t h e v a r i a t i o n i n product q u a l i t y was minimal
under the above experimental c o n d i t i o n s .
E f f e c t of Hydrogen Preaaure
Figure 4 shows t h a t HDS a c t i v i t y i n c r e a a e e with tho p a r t i a l p r e s s u r e of
hydrogen and above 6 . 6 MPa, t h e i n c r e a s e i n HDS a c t i v i t y is marginal. Although
c o n s i d e r a b l e HDS a c t i v i t y is observed a t 5 MPa ( H 2 ) , t h e HDN a c t i v i t y is q u i t e
low making i t n o t p r a c t i c a l . For t h e working c a t a l y s t , t h e k i n e t i c o r d e r w i t h
r e s p e c t t o hydrogen (over 6.6 MPa) was determined to be 0.23.
Yui and Sanford
observed a k i n e t i c o r d e r o f 0 . 8 f o r hydrogen ( 3 ) i n a t u b u l a r r e a c t o r i n t h e i r
H D 3 StUdie8 Of BCGO.
400%
LHSV-120.h-1
9
FIG.
4.
E f f e c t Of MPa ( H Z ) on HDS.
Nann e t a l . ( 5 ) assumed f i r s t o r d e r dependence f o r t h e HDS f o r t h e i r experiments i n a t u b u l a r reactor; however, t h e i r d a t a d i d n o t f i t t h o f i r s t o r d e r
p l o t . T h i s discrepancy has b w n explained on the b a s i s t h a t the i n t e r c e p t ref l e c t e d t h e e x t e n t of thermal r e a c t i o n d u r i n g HDS c a t a l y s i s . Yui and Sanford
( 3 ) observed a similar t r e n d f o r HDN of SCCO. They introduced a power term f o r
the LHSV t o account f o r t h e uneven w e t t i n g o f t h e c a t a l y s t i n t h e t u b u l a r
( t r i c k l e bed) reactor and t h e d a t a f i t t e d t h e f i r s t o r d e r p l o t . O u r d a t a p l o t t e d i n Figure 7 a l s o do n o t f i t t h e f i r s t o r d e r p l o t . Reaction o r d e r of up t o
t w o ha8 been proposed f o r HDS ( 7 ) . The developaent of simple g e n e r a l i z e d kinet i c d a t a f o r t h e HDS of d i f f e r e n t petroleum f e e d s t o c k s is complicated by t h e
f a c t t h a t t h e r e are a l a r g e number of a u l f u r compounds i n t h e petroleum and
theme may have d i f f e r e n t r e a c t i o n rates because of t h e i r s t r u c t u r a l d i f f e r e n c e s
-
850
-
as w e l l as d i f f e r e n c e s i n m o l e c u l a r weight. A d d i t i o n a l l y , t h o s e s u l f u r compounds may c a u s e changes i n t h e c a t a l y s t d u r i n g t h e reaction and t h i s c o u l d
also be r e f l e c t e d upon t h e o b s e r v e d rate.
I n f l u e n c e o f Pore D i f f u s i o n
Examination of FIG. 5 shows t h a t t h e HDS c o n v e r s i o n wer t h e 3.5 mm x
1.6 ma c a t a l y s t (Co-MO) may have been somewhat i n f l u e n c e d by pore d i f f u s i o n .
Such d e t a i l e d e x p e r i m e n t a t i o n was n o t u n d e r t a k e n f o r t h e N i - M o c a t a l y s t .
A c t i v a t i o n Energy
Data summarized i n FIG. 6 show t h a t t h e a c t i v a t i o n e n e r g y f o r t h e Co-MO
( 6 5 . 0 kJ/mole) i s lower t h a n t h a t f o r t h e Ni-Mo ( 9 3 . 4 k J / m o l e ) .
Activation
e n e r g y o f 07 kJ/mole h a been r e p o r t e d f o r HDS over a N i - N o c a t a l y s t ( 4 ) .
FIG. 5.
E f f e c t of C a t a l y s t P a r t i c l e Size (Co-Mo) on HDS.
I n f l u e n c e o f LHSV on HDS
Although t h e l e v e l of HDS i n c r e a s e d w i t h l/LHSV, and t h e d a t a f a l l on a
s t r a i g h t l i n e (FIG. 7 1 , i t does n o t p a s s t h r o u g h t h e o r i g i n ( t e s t f o r f i r s t
o r d e r r e a c t i o n ) . S i m i l a r r e s u l t s were o b t a i n e d by Mann e t a l . ( 5 ) i n a t u b u l a r
reactor.
Hydroprocessing A c t i v i t y
G e n e r a l l y two types o f r e a c t o r s are employed f o r s t u d y i n g t h e h i g h p r e s sure, h i g h t e m p e r a t u r e h y d r o p r o c e s s i n g , t u b u l a r and CSTR. I n t h e t u b u l a r reactor, t h e r e a c t a n t s (hydrogen and g a s oil) are c o n t a c t e d w i t h t h e c a t a l y s t
e i t h e r i n a c o - c u r r e n t or a c o u n t e r - c u r r e n t mode. I n t h i s complex t h r e e phase
r e a c t o r system ( g a s , s o l i d and l i q u i d ) , uniform c a t a l y s t w e t t i n g c a n n o t be ass u r e d . T h i s may be r e f l e c t e d i n t h e measured rate. However, t h e d a t a from
t h e t u b u l a r r e a c t o r may bo e x t r a p o l a t e d to commercial h y d r o p r o c e s s i n g r e a c t o r s .
I n t h e CSTR, on t h e o t h e r hand, because of t h e minimal g r a d i e n t s i n t e m p e r a t u r e
and c o n c e n t r a t i o n ( d u e to a h i g h d e g r e e o f i n t e r n a l r e c y c l i n g ) ,
determined w i t h a h i g h d e g r e e o f r e l i a b i l i t y .
Internal recycle
d e s i g n e d so that t h e r e l a t i v e v e l o c i t y between t h e c a t a l y s t and
can b e i n c r e a s e d w i t h o u t i n c r e a s i n g t h e o v e r a l l f e e d and o u t l e t
-
851
-
rates can be
reactors are
f l u i d phases
flow r a t e s .
a
H
!
FIG. 6.
Temperature C o e f f i c i e n t ofthe Rate Constant k for Co-Mo and
N i - M o Catalyato.
FIG. 7.
P l o t of In l/l-x va 1/LHSV f o r the Co-Mo c a t a l y s t .
-
852
-
T h i s f a c i l i t a t e s the i n t e r p h a s e h e a t and mass t r a n s f e r rates. T h i s t y p e of
reactor, b e c a m e o f t h e e x t e n s i v e r e c y c l i n g and t h e r e s u l t a n t minimum g r a d i e n t 8
of t e m p e r a t u r e and c o n c e n t r a t i o n w i t h i n t h e r e a c t o r , is i d e a l l y s u i t e d f o r 1ab o r a t o r y k i n e t i c s t u d i e r . The rate c o n s t a n t k may be e v a l u a t e d d i r e c t l y by
u s i n g the e q u a t i o n
s u g g e s t e d by Rangawala e t a 1 ( 4 1 , where :
ki : Rate c o n s t a n t f o r t h e ith s p e c i e s , s u l f u r f o r example.
Q e and Qo a P r o d u c t and f e e d flow rates measured a t roan t e m p e r a t u r e .
xi
I
T
: R e c i p r o c a l of s p a c e v e l o c i t y .
F r a c t i o n a l c o n v e r s i o n o f t h e ith s p e c i e s .
T h i s must be compared t o t h e i n t e g r a l e q u a t i o n ( 6 ) f o r r a t e d e t e r m i n a t i o n :
W/F
-
Idx/rp
(3)
where,
W
F
x
rp
:
Mass of c a t a l y s t
: Feedrate of r e a c t a n t
: Concentration of r e a c t a n t
: Global r a t e
per u n i t mass o f c a t a l y s t .
The N i - H o c a t a l y s t i n s p i t e o f i t s smaller pore d i a m e t e r ( a v e r a g e ) does
n o t a p p e a r to be l i m i t e d by pore d i f f u s i o n a s e v i d e n c e d by t h e a c t i v a t i o n
energy o f 93.4 kJ/mole determined f o r t h i s c a t a l y s t . T h i s is d i f f e r e n t from
t h e a c t i v a t i o n e n e r g y of 1 2 4 kJ/mole r e p o r t e d f o r c o k e r g a s oil HDS f o r t h e
p i l o t p l a n t d a t a ( 3 ) . I t is l i k e l y t h a t t h e measured a c t i v a t i o n e n e r g y depends
upon f a c t o r s s u c h as c a t a l y s t t y p e , r e a c t o r system and t h e n a t u r e o f t h e f e e d stock.
Although t h e geometry of t h e two c a t a l y s t s t h a t w e examined a s w e l l a s
r e a c t i o n c o n d i t i o n s were s i m i l a r , comparison of t h e c a t a l y s t s is d i f f i c u l t p r i m a r i l y due t o m e t a l l o a d i n g s ( i . e . 1 5 . 0 w t 8 Mooj and 2 . 9 8 COO compared t o
2 7 . 0 8 Moo3 and 6 . 7 8 N i O ) .
I n a d d i t i o n , t h e BET s u r f a c e area and t h e pore
s i z e d i s t r i b u t i o n s were also d i f f e r e n t .
However, s i n c e t h e s e t y p e of C a t a l y s t s
a r e used f o r t h e h y d r o p r o c e s s i n g c o k e r g a s oil and similar f e e d s t o c k s , it is
s t i l l i n f o r m a t i v e t o compare t h e two c a t a l y s t s .
I t can b e s e e n from FIG. 6 ,
t h a t a l t h o u g h t h e Co-Mo c a t a l y s t h a s h i g h e r a c t i v i t y a t low t e m p e r a t u r e s (below 35OoC), t h e Ni-Mo c a t a l y s t h a s b e t t e r a c t i v i t y a t h i g h e r t e m p e r a t u r e s .
However, comparing t h e rate c o n s t a n t per g o f molybdenum a t 4OO0C, t h e Co-Mo
a p p e a r s t o be s l i g h t l y more e f f i c i e n t w i t h a lower a c t i v a t i o n e n e r g y f o r HDS
t h a n t h e N i - N o c a t a l y s t . Based o n u n i t s u r f a c e area, b o t h c a t a l y s t s have simil a r HDS a c t i v i t y . I t would be v a l u a b l e t o e v a l u a t e t h e r o l e of promoters i n
t h e s e c a t a l y t i c r e a c t i o n s . Even though t h e Ni-Mo is a n a t t r a c t i v e hydroproces-
-
053
-
s i n g c a t a l y s t it s u f f e r s from poor mechanical s t r e n g t h which may be a t t r i b u t e d
to t h e h i g h metal l o a d i n g s ( 2 7 . 0 w t 0 Moo3 and 6 . 7 % NiO). I n s e l e c t i n g a cat a l y s t f o r t h e commercial h y d r o p r o c e s s i n g t h e f o l l o w i n g f a c t o r s are t a k e n i n t o
a c c o u n t : c o s t , s u s t a i n e d h i g h a c t i v i t y f o r HDS, HDN, heavy g a s oil c o n v e r s i o n ,
hydrogen consumption and r e g e n e r a b i l i t y .
ACKNOWLEDGEMENT
V a l u a b l e d i s c u s s i o n s w i t h D r . A. Hardin are a p p r e c i a t e d . Funding was prov i d e d by A l b e r t a Oil Sands Technology and Research A u t h o r i t y (AOSTPA) and ARC.
REFERENCES
1. C l a r k , K.A.;
Canadian Oil Gas Ind. 1950, 3 ( 9 ) , 1946.
2 . Fmngawala, H.A., D a l l a Lana, I . G . ,
O t t o , F.D. and Wanke, S.E. i n : C a t a l y s i s
on the Energy s c e n e , Editors : S. Kaliaguine and A. Mahay, Department d e
Genie chimique, U n i v e r s i t 6 h v a l , Quebec, Canada ( P r o c . 9 t h Can. Symp. o n
C a t a l y e i s , 1984).
3. Yui, S.M. and Sanford, E.L. P r e p r i n t s I 1 0 t h Can. Symp. on C a t a l y s i s ,
Xingston, Ontario, 1986.
4. Rangawala, H.A. e t al. Preprintm : 10th Can. Symp. o n C a t a l y s i s , Kingston,
Ontario , 1986.
5. m n n , R.S., S m b i , I.S. and Khulbe, K.C. P r e p r i n t s : 35th Can. Chem. Eng.
Conference, C a l g a r y , 1985.
6 . Whoney, J . A . ,
J. C a t a l . 32, 2 4 7 ( 7 4 ) .
7. Hydrocracking and H y d r o t r G t i n g , American Chemiaal S o c i e t y Symposium S e r i e s
2 0 , 1975, R.F. Gould, E d i t o r .
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