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Additives Effects in the Selective Hydrogenation of Unsaturated Hydrocarbons
B. Imelik e t al. (Editors), Metal-Support and Metal-Additiue Effects in Catalysis - Printed in The Netherlands
355
0 1982 Elsevier Scientific Publishing Company, Amsterdam
ADDITIVES EFFECTS I N THE SELECTIVE HYDROGENATION OF UNSATURATED HYDROCARBONS
J.P.
BOITIAUX, J. COSYNS and G. MARTINO
I n s t i t u t F r a n q a i s du P B t r o l e , B . P .
311, 92506 Rueil-Malmaison CBdex, F r a n c e
ABSTRACT T h i s p a p e r g i v e s a s h o r t r e v i e w of a d d i t i v e s e f f e c t s i n s e l e c t i v e hydrogenat i o n of u n s a t u r a t e d h y d r o c a r b o n s . B e s i d e t h e e f f e c t of r e a c t i v e i t s e l f , w e examine t h e i n f l u e n c e on t h e c a t a l y s t ' s a c t i v i t y and s e l e c t i v i t y
of v a r i o u s
a d d i t i v e s l i k e c a r b o n monoxide, s u l f u r , n i t r o g e n and c h l o r i n e compounds p r e s e n t o r added i n t h e r e a c t i v e m i x t u r e . The mechanism of a c t i o n of s u c h a d d i t i v e s i s g e n e r a l l y v e r y complex b u t i n some case t h e o b t a i n e d r e s u l t s c a n b e i n t e r p r e t e d by an e l e c t r o n i c e f f e c t o r " l i g a n d e f f e c t " or " a n t i d o t e e f f e c t " . Research i n t h i s d i r e c t i o n seems t o b e o n e o f t h e m o s t i n t e r e s t i n g way f o r improving a c t i v i t y and s e l e c t i v i t y o f h y d r o g e n a t i o n c a t a l y s t s . RESUME
C e t t e p u b l i c a t i o n p r e s e n t e une r e v u e r a p i d e d e s effets d ' a d d i t i f s d a n s l ' h y -
d r o g e n a t i o n d e s h y d r o c a r b u r e s i n s a t u r e s . A c 6 t e d e l ' e f f e t d e s r e a c t i f s eux-
m & m e s , n o u s examinons 1 ' i n f l u e n c e s u r 1 ' a c t i v i t e e t l a s e l e c t i v i t e du c a t a l y s e u r d e d i f f e r e n t s a d d i t i f s t e l s q u e monoxide d e c a r b o n e , compos6s a z o t G s , s u l f u r e s
e t chlores p r e s e n t s ou a j o u t e s d a n s l e m i l i e u r e a c t i o n n e l . L e mecanisme d ' a c t i o n d e ces a d d i t i f s est g e n e r a l e m e n t tres complexe, m a i s d a n s c e r t a i n s cas, l e s
r e s u l t a t s o b t e n u s p e u v e n t s ' i n t e r p r 6 t e r par un effet e l e c t r o n i q u e que n o u s a v o n s a p p e l e "effet l i g a n d " ou "effet a n t i d o t e " . La r e c h e r c h e d a n s cette d i r e c t i o n semble b t r e l a voie l a p l u s i n t e r e s s a n t e p o u r 1 ' a m e l i o r a t i o n d e 1 ' a c t i v i t e e t d e l a s e l e c t i v i t 4 d e s c a t a l y s e u r s d'hydrogenation.
INTRODUCTION The p r o d u c t s of t h e c o n v e r s i o n p r o c e s s e s l i k e s t e a m c r a c k i n g , f l u i d c a t a l y t i c c r a c k i n g , v i s b r e a k i n g , coking
... a r e
g e n e r a l l y n o t v a l u a b l e a s such
i
their
i m p u r i t i e s c o n t e n t , m a i n l y h i g h l y u n s a t u r a t e d h y d r o c a r b o n s , i s above t h e accept e d l e v e l f o r downstream p r o c e s s e s l i k e p o l y m e r i z a t i o n f o r i n s t a n c e . Among t h e d i f f e r e n t p u r i f i c a t i o n p o s s i b i l i t i e s t h e s e l e c t i v e h y d r o g e n a t i o n i s one of t h e most a t t r a c t i v e .
I t s main a d v a n t a g e s a r e t h e l o w c a p i t a l c o s t of
t h e r e q u i r e d i n s t a l l a t i o n and t h e low e n e r g e t i c
d u t y of such a p r o c e s s .
356 The table 1 summarizes the types of hydrogenations used in the field of the hydrocarbons. TABLE 1 Industrial purification by hydrogenation Hydrocarbon feedstock
Impurity to hydrogenate
Requested product
Specification of product
cut Acetylene Ethylene 4 2 ppm cut Propyne t Propadiene Propylene C 10 ppm cut Vinylacetylene + Butadiene + 5 100 ppm (butadiene) Methylacetylene Butenes ,(lo ppm C4 cut (butenes) Butadiene Butenes Benzene Olefines + Benzene 6 20 PPm Diolefines Gazoline Diolefines High Octane Number Diolefine $ 0 . 3 9, W Gazoline High Oxygen Stability
c2 c c3
It is apparent from this table that the hydrogenations conversion must be high to meet the product specification. Nevertheless in such drastic conditions the yield in the requested product must be as high as possible. Besides this purification way of unsaturated hydrocarbons, the selective hydrogenations could be useful for the production of important petrochemical intermediate from parent more unsaturated pure hydrocarbons, for instance, cyclopentene, naphtalene, cyclooctane, cyclododecene, cyclohexene. The catalysts need to be active and very se1ective;parallelor successively to the main reaction, many ways can consume the requested compound decreasing the yield. A typical example is the alcynes hydrogenation
:
ALCYNE
OLIGOMERS Many selectivities must consequently be considered
:
- Selectivity of the hydrogenation itself
-
Selectivity of the hydrogenation versus isomerization Selectivity of the hydrogenation versus polymerization
In the litterature, the word "selectivity" covers different thinks
:
a
yield or a ratio of products concentrations. Consequently, this selectivity is a function of conversion and often makes the comparison of published results impossible. A good approach of the selectivity requests to take into account the
kinetic aspects.
351 Based on s i m p l e Langmuir Hinshelwood e q u a t i o n (1) t h e h y d r o g e n a t i o n r a t e of
a compound A t o B c a n be w r i t t e n a s f o l l o w
w i t h bA, b
B
:
a d s o r p t i o n c o e f f i c i e n t s and ( A ) ,
( B ) t h e c o n c e n t r a t i o n s of p r o d u c t s .
The d i f f e r e n t s e l e c t i v e h y d r o g e n a t i o n s p r e s e n t e d i n t h e t a b l e 1 c a n b e s c h e m a t i c a l l y w r i t t e n i n t h e most common c o n s e c u t i v e form
:
kg
kA
A-B-C
A p p l i c a t i o n of e q u a t i o n (1) t o b o t h s t e p s of t h i s h y d r o g e n a t i o n g i v e s a f t e r i n t e g r a t i o n t h e e q u a t i o n ( 2 ) . The c o n c e n t r a t i o n of t h e r e q u e s t e d p r o d u c t ( v ) v e r s u s t h e r e s i d u a l c o n c e n t r a t i o n of t h e i m p u r i t y t o b e h y d r o g e n a t e d ( u ) i s :
where K i s an i n t e g r a t i o n c o n s t a n t . For e a c h v a l u e of R
A.B
it i s p o s s i b l e t o draw a c u r v e v = f
( u ) . A network
of s u c h c u r v e s i s shown i n f i g u r e 1. R d o e s n o t change w i t h t h e c o n v e r s i o n and c a n b e c a l l e d " i n t r i n s i c A/B
s e l e c t i v i t y " . I t i s o n l y f u n c t i o n of two r a t i o s , t h e k /k r a t i o and t h e A B b /b r a t i o . A
B
I
I
I
I
Yo B
A, = 5.00
8,
I
91.00
Fig 1 THEORETICAL NETWORK B function of residual A
Fig 2
EUTYNE HYDROGENATION
JP BOITIAUX , J CDSYNS
, EVASUDEVAN (21
358 As a n i l l u s t r a t i o n , w e have r e p r o d u c e d ( f i g u r e 2) t h e e v o l u t i o n o f b u t y n e h y d r o g e n a t i o n v e r s u s t i m e (2). S i m i l a r r e s u l t s on a c e t y l e n e have been r e c e n t l y p u b l i s h e d by Kemball and c o l l . ( 3 ) . I n b o t h c a s e s , t h e a c e t y l e n i c h y d r o g e n a t e s f i r s t and t h e o l e f i n second. T h i s r e s u l t i n d i c a t e s t h a t t h e a c e t y l e n i c d i s p l a c e s t h e o l e f i n from t h e c a t a l y s t and t h e h y d r o g e n a t i o n of t h e l a t e s t i s p o s s i b l e o n l y when t h e a c e t y l e n i c h a s almostcompletelydisappeared. The a d s o r p t i o n c o e f f i c i e n t b i s t h u s higher f o r t h e acetylenic than f o r the olefine. I f w e c o n s i d e r t h e s l o p e of t h e consumption c u r v e s of t h e s e t y p e s of hydroc a r b o n s , it i s o b v i o u s t h a t t h e o l e f i n s h y d r o g e n a t e q u i c k e r t h a n t h e a c e t y l e n i c s : k /k A
B
< 1.
T h i s r e s u l t i s g e n e r a l and h a s been showed f o r o t h e r h y d r o c a r b o n s l i k e cyclopentadiene
( 4 ) . In conclusion, the s e l e c t i v i t y R
A/B
c o n t r o l l e d by t h e v a l u e of b /b A
w i l l e s s e n t i a l l y be
B'
The a d d i t i v e s c a n d e p r e s s s i m i l a r l y b o t h r a t e s a c c o r d i n g t o a s i m p l e Langmuir model. I n t h i s c a s e , o n e o b s e r v e s no change of RAIB,
the additive acts
l i k e a non s e l e c t i v e p o i s o n . The a d d i v i t e c a n change t h i s r a t i o t h r o u g h b o t h ways :
- change of t h e b / b A
-
change of t h e k /k A
B B
value value
Many a d d i t i v e s w i l l a c t f a v o r a b l y on t h e s e l e c t i v i t y of t h e c a t a l y s t by modifying b o t h terms and a d i s t i n c t i o n between b o t h a c t i o n s i s r a t h e r d i f f i c u l t .
The o b s e r v e d s e l e c t i v i t y of c a t a l y t i c system c a n b e i n f l u e n c e d by s e v e r a l f a c t o r s . These p a r a m e t e r s a r e v e r y o f t e n t h e p r o p e r t i e s o f t h e c a t a l y s t i t s e l f . We c a n m e n t i o n f o r example t h e t y p e of t h e c a r r i e r , t h e n a t u r e of t h e m e t a l ( 5 ) , t h e q u a l i t y of t h e p r e p a r a t i o n
( m e t a l dispersion for instance
( 6 ) ) , the nature
of t h e p r e c u r s o r u s e d i n t h e i m p r e g n a t i o n ( s u l f a t e s , c h l o r i n e o r a l c a l i n e r e s i d u s ) o r a s o l i d a d d i t i v e ( d i f f e r e n t oxydes on t h e c a r r i e r o r a second m e t a l ) The r e a c t i o n m i x t u r e i s a l s o a s o u r c e of m o d i f i c a t o r s . The r e a c t a n t i t s e l f may change t h e c a t a l y t i c s p e c i e s , i t s t r a n s f o r m a t i o n t h r o u g h a p a r a l l e l way c a n produce a p o i s o n o u s p r o d u c t f o r t h e c a t a l y s t o r i t s simple a d s o r p t i o n can r e s t r u c t u r a t e t h e s u rfa ce. The f e e d s t o c k c o n t a i n s v e r y o f t e n i m p u r i t i e s i n s m a l l q u a n t i t y whose a c t i o n
i s s p e c i f i c f o r e a c h compound. A d i s t i n c t i o n i s g e n e r a l l y made between t h r e e t y p e s o f a c t i o n :
The i m p u r i t y p r o d u c e s a s i m p l e i n h i b i t i o n o f t h e a c t i v i t y and a change of s e l e c t i v i t y a s l o n g a s i t i s p r e s e n t i n t h e f e e d s t o c k . When i t s c o n t e n t i s again n u l l the action disappears.
0
The a c t i o n of t h e i m p u r i t y c o n t i n u e s a f t e r i t s d i s p a r i t i o n from t h e
f e e d s t o c k b u t a " r e a c t i v a t i o n " o r " r e g e n e r a t i o n " t r e a t m e n t restores t h e i n i t i a l properties. 0
The a c t i o n of t h e a d d i t i v e i s permanent and no t r e a t m e n t c a n s u p p r e s s
the modification. T h i s d i s t i n c t i o n i s v e r y i m p o r t a n t p r a c t i c a l l y b u t h a s no o b j e c t on a fundam e n t a l b a s i s where o n e h a s o n l y t o examine t h e m o d i f i c a t i n g a c t i o n on t h e a d s o r p t i o n and k i n e t i c c o n s t a n t s . I n t h e f o l l o w i n g t e x t , we w i l l s t u d y i n some d e t a i l s t h e a c t i o n o f c e r t a i n a d d i t i v e s on t h e s e l e c t i v i t y . We e x c l u d e from o u r s u b j e c t t h e r o l e of t h e n a t u r e o f t h e a c t i v e m e t a l and the a c t i o n of t h e support. W e a l s o i g n o r e t h e numerous c a s e s where t h e m o d i f i c a t i o n i s produced by t h e
a d j o n c t i o n o f a second metal t o t h e a c t i v e one.
EFFECTS O F ADDITIVES Rearrangement o f t h e c a t a l y s t by t h e r e a c t i v e The c a t a l y s i s b e i n g a c o n t a c t p r o c e s s , t h e r e a c t i o n needs a n a d s o r p t i o n o f t h e r e a c t i o n on t h e c a t a l y t i c s i t e s . One c o n s i d e r g e n e r a l l y t h a t t h e s i t e " a c t i v a t e s " t h e a d s o r b a t e by m o d i f y i n g i t s s t r u c t u r e o r i t s e n e r g y . I n a n o p p o s i t e d i r e c t i o n , t h e a d s o r b e d s p e c i e s c a n a l s o modify t h e s i t e and t h i s m o d i f i c a t i o n i s h i g h e r f o r t h e s u b s t r a t e more a d s o r b e d . A c o m p l e t e r e c o n s t r u c t i o n of
t h e c a t a l y t i c s u r f a c e h a s been d e m o n s t r a t e d i n
c e r t a i n c a s e s . F o r i n s t a n c e , Burwell and coworkers
( 7 ) show t h a t t h e a c t i v i t y
of p l a t i n u m o n a l u m i n a c a t a l y s t s i n c r e a s e s d u r i n g t h e h y d r o g e n a t i o n o f 3.hexyne.
T h e i r i n t e r p r e t a t i o n o f t h e phenomena i n v o k e s a " s e m i e x t r a c t i v e "
a d s o r p t i o n o f t h e hydrocarbon o n t h e p l a t i n u m . The p l a t i n u m atoms a r e l i f t e d above t h e s u r f a c e c r y s t a l p l a n e s and p r o d u c e h i g h e r a c t i v i t y s i t e s . T h i s e x t r a c t i v e p r o c e s s c a n b e so i n t e n s e t h a t t h e metal atoms a r e e x t r a c t e d by t h e h y d r o c a r b o n s . During t h e h y d r o g e n a t i o n of v i n y l a c e t y l e n e , t h e c a t a l y s t l o s s e s a n i m p o r t a n t p a r t of i t s m e t a l by c o m p l e x a t i o n . The phenomena of r e s t r u c t u r a t i o n i s v e r y d e m o n s t r a t i v e i n t h e b i m e t a l l i c c a t a l y s t s . The a d s o r p t i o n o f a n o r g a n i c s p e c i e s e n r i c h e s t h e s u r f a c e w i t h t h e
m e t a l whose a f f i n i t y f o r t h i s s p e c i e s i s t h e h i g h e s t . I t i s t h e c a s e of t h e Pt-Au,
Pd-Ag,
Pt-Ag a l l o y s . The c h i m i s o r p t i o n of CO i s i n f a v o u r of P t and
P d ( 8 , 9 , 10) a n d t h e c h i m i s o r p t i o n o f oxygen i n f a v o u r o f s i l v e r (11, 1 2 ) .
T h i s r e s t r u c t u r a t i o n of t h e c a t a l y t i c s u r f a c e by t h e r e a c t i v e o c c u r s a l s o i n t h e case o f t h e L i n d l a r c a t a l y s t , w i t h p a l l a d i u m and l e a d
(24). This c a t a l y s t
a f t e r r e d u c t i o n i s formed by a l e a d f i l m c o v e r i n g t h e p a l l a d i u m ( 1 4 ) and a good a c t i v i t y o f s u c h a c a t a l y s t r e q u i r e s a n i n d u c t i o n p e r i o d d u r i n g which t h e
360 acetylenic species extract the palladium atoms. In certains cases, the reaction produces poisons which accumulate on the catalyst and change the catalytic behaviour
:
on the fresh catalyst the reactives
have direct access to the catalytic site and the reaction is kinetically controlled by the diffusion. In this case, the selectivity S becomes
6
(15)
;
the influence of the poison
on selectivity due to the apparition of a diffusion control has been well explicited by de Aguirre (16) and colL and Hegedus and coll. (17). Additives in the reaction mixture The modification of the catalytic sites Can also be produced by foreign compounds present originaly in the feedstock or voluntary added. Many works have been made on CO, amines, sulfur addition and several additions are used industrially (18, 19, 20). Carbon monoxide The figure 3 is obtained from data published by Kemball andcoll. ( 3 ) with the formalism introduced before. The CO promotion of the selectivity is clear. The CO can also depress the isomerization activity of palladium as demonstrated by Furukawa and coll. (21) which have studied the hydrogenation of butadiene to 1.butene and its subsequent isomerization to 2.butenes.
1004
99. P = 1 Atrn
FEED
98.
'
97
FEED
:
9725 %CZH4 275 %CZHZ
d 1
01
-
0.01 % CZH2
Fig.3 INFLUENCE OF CO ON
ACETYLENE HYDROGENATION
361 Nitrogen compounds Selectivation of the catalysts by nitrogen containing compounds has been widely used (see table 2) and has been studied for a long time. One considers generally two ways of action of this aminogroup
:
asimple adsorption competi-
tion or a charge transfer from the free nitrogen doublet towards the metal whose electronic environment is modified. This interaction metal-additives has been examined for the homogeneous and heterogeneous catalysts by Boulinguiez (33). TABLE 2 Effect of nitrogen compounds
Catalyst Palladium
Additive
Quinoline, pyridine Acetylenics Pyridine
Nickel
Reaction
+
Pb(Ac0)
Reference
+ Ethylenics
22,23,24,25,26 27
2
Piperidine Piperidine
28
+
29
Pb (AcO) Palladium
Primary amine
Cyclodiene
+Cyclodecene
30
Nickel, Iron or cobalt arseniate or antimonate
NH OH, amines
Diolefins
+ Monoolefins
31,32
4
The table 3 extracted from his work emphasizes the additive effect on pyridine on the selectivity of hydrogenation of isoprene. The intermediate olefins are subsequently hydrogenated with a substantially decreased rate. This phenomena has been explained by the change of the retrodonation bonding induced by the modification of the electronic character of the metal (34). TABLE 3 Hydrogenation of isoprene - Product repartition
Products
2 M B2
Pyridine
-
+ 2 M B1
-
t
3
M
B1
I C 5
-
+
+
1 0 mn
40 36 30 40 0
20 30 4
25 mn 43 36,5 16 39 0
19 41 585
50 mn
75 mn 39,5 39 3,5 36
41 39 8 36,5
0
0
14
16,5 51 8
20 % isoprene/80 % cyclohexane Reaction : 20 Catalyst : homogeneous and supported nickel
57 11 OC
0.9 MPa
362 S i m i l a r e f f e c t s have been o b s e r v e d by Vasudevan and c o l l . i n t h e hydrogena-
( 3 5 ) . The a d d i t i o n of p i p e r i d i n e
t i o n of 1-butyne on p a l l a d i u m o v e r alumina
d e p r e s s e s t h e h y d r o g e n a t i o n r a t e o f 1 - b u t e n e b u t promotes t h e h y d r o g e n a t i o n of 1-butyne
( f i g u r e 4 ) . T h i s promotion e f f e c t c a n b e i n t e r p r e t e d a s a " l i g a n d
e f f e c t' I . T h i s promoting e f f e c t of t h e h y d r o g e n a t i o n r a t e h a s a l s o been shown on homogeneous n i c k e l and c o b a l t c a t a l y s t
(36) i n t h e h y d r o g e n a t i o n of c y c l o p e n t a d i e n e .
Besides t h e h i g h e r s e l e c t i v i t y t o cyclopentene, t h e hydrogenation r a t e of cyclopentadiene i s s u b s t a n t i a l l y increased.
H2 consumption
T= 20'C
P= E M p o
Cola
. 0 3%
A)
No
PdlAlumino
pipendine
6 ) 0.8cc piperidine in lOcc butyne ILButyne
200
I
I
10
20
30
40 Time (rnn)
Fig 4 INFLUENCE OF PlPERlDlNE ON HYDROGENATION RATE OF 1-BUTYNE AND 1-BUTENE
S u l f u r compounds The name s u l f u r compounds c o v e r s a b i g v a r i e t y of p r o d u c t s a s H S , m e r c a p t a n s , 2 e l e m e n t a l s u l f u r , whose a c t i o n on t h e c a t a l y s t s w i l l be
thiophene, p o l y s u lfid e,
d i f f e r e n t . Only c e r t a i n a s p e c t s have been p r e s e n t e d h e r e . The s u l f u r a d d i t i v e s a r e v e r y o f t e n i m p u r i t i e s of t h e f e e d s t o c k s and i n d u s -
t r i a l c a t a l y s t s a r e d e s i g n e d and s e l e c t e d by t h e i r a b i l i t y t o keep a s u f f i c i e n t a c t i v i t y i n t h e i r presence. Many t i m e s , s u c h compounds a r e v o l u n t a r y added t o o b t a i n a b e t t e r s e l e c t i v i t y of p a r a l l e l o r c o n s e c u t i v e r e a c t i o n s . A s h o r t l i s t of s u c h m o d i f i c a t i o n s i s
g i v e n i n t a b l e 4.
363 TABLE 4 Effect of sulfur compounds
Catalyst
Additive
Reaction
Co and Ni (bulk) H S and thiophene
Ni/A1 0 2 3 Ni/Kieselguhr Ni/A1 S 2 3
Butadiene 'I4 2 Various S compounds Isoprene ?CS
2 Sulfided carrier
Reference
-
additio$ butene 2
37,38
methylbutenes
39
cycloolefin
40
Olefine 1,4 additio Isoprene ) mephylbutene 2
41
Cyclotriene Diene
Pd/A1203
Thiophene
Ni-NiO
Various Scompounds Octyne
Ni S 2 2
H S 2
-
Acetylene
42
octene
43
ethylene
44
The figures 5a and 5b show a very demonstrative example of the influence of thiophene on the hydrogenation selectivity of isoprene
:
decreasing of paraffin
formation and promotion of 1-4 addition. Again the sulfided molecules have two actions. A competition for the metal surface between sulfide and substrate, the adsorption of sulfided species can sometimes be a more or less complete sulfuration of the metal, and an electronic transfer between the sulfur doublet and the metal.
100
75
50
25
0
50
100
150
200
H2 consumption (%)
Fig 5a
Fig. 5a. Hydrogenation of isoprene on Raney nickel without thiophene. P = isopentane
2-1
=
2 methylbutene 1
2-2 = 2 methylbutene 2 3-1 = 3 methylbutene 1
364
75
Raney Nickel = 0.61q
50
25
0
50
100 H2 consumption(%I
Fig.5b
Fig. 5b. Hydrogenation of isoprene on Raney n i c k e l i n presence of thiophene.
0
Coreactif e f f e c t
Solvent e f f e c t s o n hydrogenation r a t e s a r e well known (33, 46) and have been evaluated k i n e t i c a l l y ( 4 7 ) . The a d d i t i v e e f f e c t examined h e r e above can be obtained with c o r e a c t i v e s . The t a b l e 5 p r e s e n t s t h e i n f l u e n c e of p i p e r i d i n e , isoprene and butadiene on t h e hydrogenation r a t e of I-butyne and t h e s e l e c t i v i t y t o butene ( 4 8 ) . TABLE 5
E f f e c t of a d d i t i v e and c o r e a c t i v e on butyne hydrogenation
n heptane Turn over (mol atg-1 S-1 ) 8
9.1
n heptane + 0.8ccpiperidine
isoprene
23.4
23.1
3.1
1.5
bu t a d i ene
20.5
butane formed a t 99 %
18
-
1-butyne conversion 0.3 % Pd/A1 0 Dispersion 60 % 2 3 P = 2 MPa T = 2 0 'C Operating c o n d i t i o n s : Catalyst
Feedstock
:
:
10 c c 1-butyne
+
90 c c s o l v e n t or c o r e a c t i v e
The a c t i o n of isoprene and butadiene i s very s i m i l a r t o t h e a c t i o n of p i p e r i d i n e . The a c t i v i t y of hydrogenation and t h e s e l e c t i v i t y a r e promoted. The Unsaturated hydrocarbons have h e r e t h e r o l e of a l i g a n d i n a s i m i l a r way
365 t o t h e p i p e r i d i n e . T h i s l i g a n d e f f e c t i s known i n homogeneous c a t a l y s i s a n d a p p l i c a t i o n of s u c h a d d i t i v e h a s been p a t e n t e d f o r s o l u b l e and s u p p o r t e d catal y s t s (49). a Other a d d i t i v e s A l o t of o t h e r o r g a n i c and i n o r g a n i c compounds have been u s e d f o r m o d i f i c a -
t i o n of c a t a l y s t s ( t a b l e 6 ) . TABLE 6
E f f e c t of miscallaneous a d d i t i v e s
Catalyst
Additives
Reaction
RU
Phosphorus a c i d / w a t e r
Aromatic
Pd/A1203
C12, N 2 0
Butadiene
RuCl
Reference _ j
cycloolefin
50
1- b u t e n e
21
3 Pd/A1203
B a s i c compound
Aromatic
N methylpyrrolidone
Butadiene p u r i f i c a t i o n
d cycloolefin
Ni
Phosphines
Isoprene
51 52
d methylbutenes
33
S i m i l a r e f f e c t s have been d e m o n s t r a t e d on s u p p o r t e d homogeneous c a t a l y s t s on non c o n v e n t i o n n a l s u p p o r t s ( l i k e n y l o n and r e s i n s , ( 3 4 ) )
.
A q u a n t i f i c a t i o n o f t h e a d d i t i v e s e f f e c t h a s n o t y e t been made e x c e p t b y a
few w o r k e r s l i k e Maurel and c o l l .
( 5 3 ) who d e f i n e a t m x i c i t y i n d e x of p o i s o n s
and examine t h e i r e f f e c t on t h e h y d r o g e n a t i o n and d e u t e r a t i o n o f benzene. 0
Combined e f f e c t s o f s e v e r a l a d d i t i v e s
S e v e r a l m o d i f i c a t i o n e f f e c t s among t h o s e shown h e r e above c a n b e combined on a same c a t a l y s t and g i v e a p o s s i b l e a c t i o n on t h e a c t i v i t y and s e l e c t i v i t y of t h e c a t a l y s t . For i n s t a n c e , t h e c o m p e t i t i v e h y d r o g e n a t i o n of t o l u e n e and benzene h a s been s t u d i e d w i t h s u l f u r , n i t r o g e n and c h l o r i n e compounds i n t h e feed (54). The t a b l e ? a shows t h e i n f l u e n c e of s u l f u r , of n i t r o g e n and o f m i x t u r e s of b o t h , on t h e s e l e c t i v i t y t o l u e n e / b e n z e n e
( R T B ) . The i n c r e a s i n g e f f e c t on t h i s
s e l e c t i v i t y o f 50 ppm of s u l f u r i n p r e s e n c e o f 950 ppm o f n i t r o g e n i s as import a n t as t h e e f f e c t o f 800 ppm of s u l f u r a l o n e . On t h e o t h e r hand,
1000 ppm
n i t r o g e n a l o n e g i v e t h e same RTB a s t h e p l a t i n u m w i t h o u t a d d i t i v e . The t a b l e l b i n d i c a t e s t h e i n f l u e n c e o f n i t r o g e n and c h l o r i n e combined w i t h s u l f u r on t h e a c t i v i t y of h y d r o g e n a t i o n o f t o l u e n e and benzene. The e f f e c t of n i t r o g e n and c h l o r i n e a r e o p p o s i t e when added w i t h s u l f u r . The nitrogen i n c r e a s e s t h e poisoning e f f e c t of s u l f u r while t h e c h l o r i n e has an "antidote" effect. T h e s e b e h a v i o u r s have been i n t e r p r e t e d by a v a r y i n g s u l f u r i z a t i o n e q u i l i b r i u m , t h e e l e c t r o d o n o r compound ( t h e n i t r o g e n ) r e i n f o r c i n g t h e m e t a l - s u l f u r bond and
366 the electroacceptor one (the chlorine) labilizing the same. TABLE ?a Relative reactivities of toluene/benzene on platinum/alumina (RTB) P = 4.5 MPa
T = 300 'C
WH = 8
0.6
0
0 f 1000
(1
50
1.25
50
f
950
1.74
200
1.53
200 +
000
1.83
500
1 .6a
500
f
500
2 .oo
800
1.77
aoo
t
200
2.10
-
1 .ao
1000
-
TABLE ?b Toluene
+
benzene hydrogenation activity on platinum/alumina P = 4.5 MPa
T = 300 'C
Additives
VVH = 8
Rate of hydrogenation toluene + benzene 2 mol./g-lh-' x 10
~
I
l o 0 0 ppm N
500 ppm
S i500
500 ppm
S
+
1
S
500 ppm
ppm N
500 ppm C1
0.14
1.8
CONCLUSION This short review has shown some examples of the numerous possibilities of additives for modifying the activity and selectivity of hydrogenation catalysts. It is obvious that their mechanism of action is a very complex matter. Likely, we may assume that several effects can be produced by a single additive . For example, active site blocking, surface restructuration and electronic effects could be obtained with sulfur on certain metals. We have also to take into account the surface heterogeneity of solid catalyst. Generally speaking, it would be very interesting to increase our knowledge in order to decide if one additive acts on the intrinsic activity or on the reactant adsorbtion or on both. Nevertheless, in some interesting cases,
367 e l e c t r o n i c e f f e c t s have t o b e invoked when b o t h a c t i v i t y and s e l e c t i v i t y a r e i n c r e a s e d a s i t c a n b e s e e n f o r example w i t h some n i t r o g e n compounds i n t h e h y d r o g e n a t i o n o f l . b u t y n e and c y c l o p e n t a d i e n e .
These e f f e c t s are observed
e i t h e r on homogeneous o r s o l i d C a t a l y s t s . They c a n b e e x p l a i n e d b y t h e t o o s t r o n g c o m p l e x a t i o n o f t h e h i g h l y u n s a t u r a t e d h y d r o c a r b o n s . I n t h i s case, t h e e f f e c t of t h e a d d i t i v e , which c a n b e c a l l e d " l i g a n d e f f e c t " i s t o d e c r e a s e t h i s c o m p l e x a t i o n s t r e n g t h and c o n s e q u e n t l y t o enhance a c t i v i t y and s e l e c t i v i t y . The d e c r e a s e of s u l f u r p o i s o n i n g by a d d i n g a second " a n t i d o t e a d d i t i v e " l i k e c h l o r i n e compounds may a l s o b e e x p l a i n e d by a d e c r e a s e o f s u l f u r bounding t o t h e metal. T h i s k i n d of e l e c t r o n i c e f f e c t seems t o u s t h e most p r o m i s i n g d i r e c t i o n t o b e choosen f o r q u a n t i t a t i v e s t u d y of a d d i t i v e s a c t i o n .
I t w i l l p r o v i d e u s one
of t h e most u s e f u l t o o l f o r improving a c t i v i t y and s e l e c t i v i t y o f h y d r o g e n a t i o n catalysts.
REFERENCES J u n g e r s and c o l l . , C i n e t i q u e chimique a p p l i q u & e , Technip Ed., Q980) p . 409. B o i t i a u x , J. Cosyns and S. Vasudevan, s u b m i t t e d f o r p u b l i c a t i o n i n iq p p l i e d C a t a l y s i s . 3 IY.T. Mac Gown, C . Kemball, D. Whan and M.S. S c u r e l l , T r a n s . F a r a d a y S O C . ,
1 J.C. 2 J.P.
73 (1977) 632. 4 Ij. B o u l i n g u i e z , t h e s i s P a r i s , Technip Ed. ( 1 9 7 6 ) . 5 f;.C. Bond, C a t a l y s i s by m e t a l s , Academic P r e s s (1962) P . 2926 J.P. B o i t i a u x , J . Cosyns and S . Vasudevan, T h i r d I n t . Symposium f o r t h e ? r e p a r a t i o n of h e t e r o g e n e o u s c a t a l y s t s , Louvain-la-Neuve ( 1 9 8 2 ) . 98:18 (1976) 5603. 7 3 . H . Kung, R . J . P e l l e t and R . L . Burwell J r , J.A.C.S., S a c h t l e r a n d P . Van d e r P l a n c k , S u r f . S c i . 18 (1969) 62. 8 Y.M.H. 9 i . Bowman, G . J . M . L i p p e t s and W . H . M . S a c h t l e r , J . C a t a . 25 (1972) 360. 10 R. Bowman and W.H.M. S a c h t l e r , J. C a t a . 19 (1970) 127. 11 R.L. Moss and D . H . Thomas, J. C a t a . 8 (1967) 151. 12 R.L. Moss and D . H . Thomas, J. C a t a . 8 (1967) 162. 13 I . d e A g u i r r 6 a n d B. Duque, P r o c e e d i n g s o f t h e I n t . Symposium on t h e r e l a t i o n s between homogeneous and h e t e r o g e n e o u s c a t a l y t i c phenomena, B r u x e l l e s
(1974) 26. 14 H . L i n d l a r , Helv. Chim., Acta 35 (1952) 446, Org. S y n t h . 46 (1966) 89. 15 J . F . Le Page, C a t a l y s e d e c o n t a c t , T e c h n i p Ed. 43. 16 I . d e A g u i r r 6 and B. Duque, P r o c e e d i n g s of t h e I n t . Symposium on t h e r e l a t i o n s between h e t e r o g e n e o u s and homogeneous c a t a l y t i c phenomena, B r u x e l l e s
(1974) 12. 17 18 19 20 21 22 23 24 25 26 27
L o u i s Heqedus and R o b e r t W. Mc Cabe, C a t a l . Rev. S c i . Eng. 23 (1981) 377. Maruzen O i l Company, U.S. P a t e n t 3,674,886. DOW Chemical Company, Dutch P a t e n t 7,115,019. Dow Chemical Company, U . S . P a t e n t 3,634,536. Y a s u h i r o Furukawa, A k i r a Yokogawa, T a k a s h i Yokomizo and Y o u j i Komatsu, B u l l e t i n of t h e J a p a n P e t r o l e u m I n s t i t u t e , 15 (1973) 56. 0. I s l e r , W. Huber, A . Ronco and M. K e f l e r , Helv. Chim., A c t a 30 (1947) 1911. E.N. Marvell and T. L i , S y n t h e s i s 8 (1973) 457. E.N. M a r v e l l , T. Gosink and P . C h u r c h l e y , J. Org. Chem. 37 (1972) 2989. S o k o l " s k a y a , K i n e t . K a t a l . 12 (1971) 525. D . V . S o k o l ' s k i i and P . Gadenov, J z v . Akad. Nauk. S e r . Khim. 20 (1970) 62. H . L i n d l a r , Helv. Chim. A c t a 35 (1952) 446, Org. S y n t h e s i s 46 (1966) 8 9 . L.
368 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
W. O r o s h n i k and A . D . Mebane, J . Amer. Chem. SOC. 76 (1954) 5719. W. O r o s h n i k , G. K a r m a s and A . D . Mebane, J . Amer. CQem. SOC. 74 (1952) 3807. U.O.P. U.S. P a t e n t 3 , 4 3 3 , 8 4 2 . P h i l l i p p s P e t r o l e u m , U.S. P a t e n t 3 , 6 3 7 , 8 7 7 . P h i l l i p p s Petroleum, U . S . P a t e n t 3,636,175. D. B o u l i n g u i e z , T h e s i s P a r i s , T e c h n i p Ed. ( 1 9 7 6 ) . D. Commereuc and G . M a r t i n o , Rev. I n s t . Franr;. du P e t r o l e , 3 0 (1975) 8 9 . J . P . B o i t i a u x , J . Cosyns and S. Vasudevan, t o be p u b l i s h e d . D. Durand, T h e s i s P a r i s ( 1 9 7 4 ) . Y . Okamoto, K. F u k i n o , T. Imanaka and S . T e r a n i s h i , J . C a t a l . 74 (1982) 173. M. George, R . B . Moyes, D. Ramanarov and P . B . W e l l s , J . C a t a l . 52 (1978) 486. K . H . Bourne, P.D. Holmes and R . C . P i t k e t h l y , T h i r d I n t . Cong. on C a t a l y s i s , Amsterdam (1964) P r e p r i n t s P a p e r N o 11, 16. A q u i t a i n e O r g a n i c o , U.S. P a t e n t 3 , 5 7 6 , 8 9 4 . S h e l l O i l , U.S. P a t e n t 4 , 0 7 8 , 0 1 1 . J . Cosyns and J . P . B o i t i a u x , u n p u b l i s h e d r e s u l t s . A . Koppova, V. Z a p l e t a l , V. Ruzicka and J . Sonkup, C o l l e c t . C z e c h o s l . Chem. Commun. 38 (1973) 2466. R . E . R e i t m e i e v and H.W. F l e m i n g , Chem. Eng. P r o g . 54 (1958) 4 8 . J. V e r b o i s , T h e s i s Louvain ( 1 9 7 0 ) . L . Cerveny, A . P r o c h a z k a and V . R u z i c k a , C o l l . C z e c h o s l o v . Chem. Commun. 39 (1974) 2463. A . Lozowski, T h e s i s Louvain ( 1 9 7 3 ) . J . Cosyns, N . T a g u i z a d e h and S . Vasudevan, t o b e p u b l i s h e d . I . F . P . , U.S. P a t e n t 3 , 9 2 2 , 3 1 8 . Toray I n d u s t r i e s , U.S. P a t e n t 4 , 1 9 7 , 4 1 5 . E . I . Dupont d e Nemours, B e l g i s h P a t e n t 782,721. K. Volkamer, K . J . S c h n e i d e r , A . L i n d n e r a n d and D . Bender, E r d o e l und Kohle, E r d g a s - P e t r o c h e m i e v e r e i n i g t m i t Brennstoff-Chemie 34 (1981) 344. R. Maurel and J . B a r b i e r , J . d e c h i m i e p h y s i q u e , 73 (1976) 9 9 5 , 75 (1978) 410. J . Cosyns, J . P . F r a n c k and 2 . Marin G i l , C . R . Acad. S c . P a r i s 287 (1978) 8 5 , 288 (1979) 25.
355
0 1982 Elsevier Scientific Publishing Company, Amsterdam
ADDITIVES EFFECTS I N THE SELECTIVE HYDROGENATION OF UNSATURATED HYDROCARBONS
J.P.
BOITIAUX, J. COSYNS and G. MARTINO
I n s t i t u t F r a n q a i s du P B t r o l e , B . P .
311, 92506 Rueil-Malmaison CBdex, F r a n c e
ABSTRACT T h i s p a p e r g i v e s a s h o r t r e v i e w of a d d i t i v e s e f f e c t s i n s e l e c t i v e hydrogenat i o n of u n s a t u r a t e d h y d r o c a r b o n s . B e s i d e t h e e f f e c t of r e a c t i v e i t s e l f , w e examine t h e i n f l u e n c e on t h e c a t a l y s t ' s a c t i v i t y and s e l e c t i v i t y
of v a r i o u s
a d d i t i v e s l i k e c a r b o n monoxide, s u l f u r , n i t r o g e n and c h l o r i n e compounds p r e s e n t o r added i n t h e r e a c t i v e m i x t u r e . The mechanism of a c t i o n of s u c h a d d i t i v e s i s g e n e r a l l y v e r y complex b u t i n some case t h e o b t a i n e d r e s u l t s c a n b e i n t e r p r e t e d by an e l e c t r o n i c e f f e c t o r " l i g a n d e f f e c t " or " a n t i d o t e e f f e c t " . Research i n t h i s d i r e c t i o n seems t o b e o n e o f t h e m o s t i n t e r e s t i n g way f o r improving a c t i v i t y and s e l e c t i v i t y o f h y d r o g e n a t i o n c a t a l y s t s . RESUME
C e t t e p u b l i c a t i o n p r e s e n t e une r e v u e r a p i d e d e s effets d ' a d d i t i f s d a n s l ' h y -
d r o g e n a t i o n d e s h y d r o c a r b u r e s i n s a t u r e s . A c 6 t e d e l ' e f f e t d e s r e a c t i f s eux-
m & m e s , n o u s examinons 1 ' i n f l u e n c e s u r 1 ' a c t i v i t e e t l a s e l e c t i v i t e du c a t a l y s e u r d e d i f f e r e n t s a d d i t i f s t e l s q u e monoxide d e c a r b o n e , compos6s a z o t G s , s u l f u r e s
e t chlores p r e s e n t s ou a j o u t e s d a n s l e m i l i e u r e a c t i o n n e l . L e mecanisme d ' a c t i o n d e ces a d d i t i f s est g e n e r a l e m e n t tres complexe, m a i s d a n s c e r t a i n s cas, l e s
r e s u l t a t s o b t e n u s p e u v e n t s ' i n t e r p r 6 t e r par un effet e l e c t r o n i q u e que n o u s a v o n s a p p e l e "effet l i g a n d " ou "effet a n t i d o t e " . La r e c h e r c h e d a n s cette d i r e c t i o n semble b t r e l a voie l a p l u s i n t e r e s s a n t e p o u r 1 ' a m e l i o r a t i o n d e 1 ' a c t i v i t e e t d e l a s e l e c t i v i t 4 d e s c a t a l y s e u r s d'hydrogenation.
INTRODUCTION The p r o d u c t s of t h e c o n v e r s i o n p r o c e s s e s l i k e s t e a m c r a c k i n g , f l u i d c a t a l y t i c c r a c k i n g , v i s b r e a k i n g , coking
... a r e
g e n e r a l l y n o t v a l u a b l e a s such
i
their
i m p u r i t i e s c o n t e n t , m a i n l y h i g h l y u n s a t u r a t e d h y d r o c a r b o n s , i s above t h e accept e d l e v e l f o r downstream p r o c e s s e s l i k e p o l y m e r i z a t i o n f o r i n s t a n c e . Among t h e d i f f e r e n t p u r i f i c a t i o n p o s s i b i l i t i e s t h e s e l e c t i v e h y d r o g e n a t i o n i s one of t h e most a t t r a c t i v e .
I t s main a d v a n t a g e s a r e t h e l o w c a p i t a l c o s t of
t h e r e q u i r e d i n s t a l l a t i o n and t h e low e n e r g e t i c
d u t y of such a p r o c e s s .
356 The table 1 summarizes the types of hydrogenations used in the field of the hydrocarbons. TABLE 1 Industrial purification by hydrogenation Hydrocarbon feedstock
Impurity to hydrogenate
Requested product
Specification of product
cut Acetylene Ethylene 4 2 ppm cut Propyne t Propadiene Propylene C 10 ppm cut Vinylacetylene + Butadiene + 5 100 ppm (butadiene) Methylacetylene Butenes ,(lo ppm C4 cut (butenes) Butadiene Butenes Benzene Olefines + Benzene 6 20 PPm Diolefines Gazoline Diolefines High Octane Number Diolefine $ 0 . 3 9, W Gazoline High Oxygen Stability
c2 c c3
It is apparent from this table that the hydrogenations conversion must be high to meet the product specification. Nevertheless in such drastic conditions the yield in the requested product must be as high as possible. Besides this purification way of unsaturated hydrocarbons, the selective hydrogenations could be useful for the production of important petrochemical intermediate from parent more unsaturated pure hydrocarbons, for instance, cyclopentene, naphtalene, cyclooctane, cyclododecene, cyclohexene. The catalysts need to be active and very se1ective;parallelor successively to the main reaction, many ways can consume the requested compound decreasing the yield. A typical example is the alcynes hydrogenation
:
ALCYNE
OLIGOMERS Many selectivities must consequently be considered
:
- Selectivity of the hydrogenation itself
-
Selectivity of the hydrogenation versus isomerization Selectivity of the hydrogenation versus polymerization
In the litterature, the word "selectivity" covers different thinks
:
a
yield or a ratio of products concentrations. Consequently, this selectivity is a function of conversion and often makes the comparison of published results impossible. A good approach of the selectivity requests to take into account the
kinetic aspects.
351 Based on s i m p l e Langmuir Hinshelwood e q u a t i o n (1) t h e h y d r o g e n a t i o n r a t e of
a compound A t o B c a n be w r i t t e n a s f o l l o w
w i t h bA, b
B
:
a d s o r p t i o n c o e f f i c i e n t s and ( A ) ,
( B ) t h e c o n c e n t r a t i o n s of p r o d u c t s .
The d i f f e r e n t s e l e c t i v e h y d r o g e n a t i o n s p r e s e n t e d i n t h e t a b l e 1 c a n b e s c h e m a t i c a l l y w r i t t e n i n t h e most common c o n s e c u t i v e form
:
kg
kA
A-B-C
A p p l i c a t i o n of e q u a t i o n (1) t o b o t h s t e p s of t h i s h y d r o g e n a t i o n g i v e s a f t e r i n t e g r a t i o n t h e e q u a t i o n ( 2 ) . The c o n c e n t r a t i o n of t h e r e q u e s t e d p r o d u c t ( v ) v e r s u s t h e r e s i d u a l c o n c e n t r a t i o n of t h e i m p u r i t y t o b e h y d r o g e n a t e d ( u ) i s :
where K i s an i n t e g r a t i o n c o n s t a n t . For e a c h v a l u e of R
A.B
it i s p o s s i b l e t o draw a c u r v e v = f
( u ) . A network
of s u c h c u r v e s i s shown i n f i g u r e 1. R d o e s n o t change w i t h t h e c o n v e r s i o n and c a n b e c a l l e d " i n t r i n s i c A/B
s e l e c t i v i t y " . I t i s o n l y f u n c t i o n of two r a t i o s , t h e k /k r a t i o and t h e A B b /b r a t i o . A
B
I
I
I
I
Yo B
A, = 5.00
8,
I
91.00
Fig 1 THEORETICAL NETWORK B function of residual A
Fig 2
EUTYNE HYDROGENATION
JP BOITIAUX , J CDSYNS
, EVASUDEVAN (21
358 As a n i l l u s t r a t i o n , w e have r e p r o d u c e d ( f i g u r e 2) t h e e v o l u t i o n o f b u t y n e h y d r o g e n a t i o n v e r s u s t i m e (2). S i m i l a r r e s u l t s on a c e t y l e n e have been r e c e n t l y p u b l i s h e d by Kemball and c o l l . ( 3 ) . I n b o t h c a s e s , t h e a c e t y l e n i c h y d r o g e n a t e s f i r s t and t h e o l e f i n second. T h i s r e s u l t i n d i c a t e s t h a t t h e a c e t y l e n i c d i s p l a c e s t h e o l e f i n from t h e c a t a l y s t and t h e h y d r o g e n a t i o n of t h e l a t e s t i s p o s s i b l e o n l y when t h e a c e t y l e n i c h a s almostcompletelydisappeared. The a d s o r p t i o n c o e f f i c i e n t b i s t h u s higher f o r t h e acetylenic than f o r the olefine. I f w e c o n s i d e r t h e s l o p e of t h e consumption c u r v e s of t h e s e t y p e s of hydroc a r b o n s , it i s o b v i o u s t h a t t h e o l e f i n s h y d r o g e n a t e q u i c k e r t h a n t h e a c e t y l e n i c s : k /k A
B
< 1.
T h i s r e s u l t i s g e n e r a l and h a s been showed f o r o t h e r h y d r o c a r b o n s l i k e cyclopentadiene
( 4 ) . In conclusion, the s e l e c t i v i t y R
A/B
c o n t r o l l e d by t h e v a l u e of b /b A
w i l l e s s e n t i a l l y be
B'
The a d d i t i v e s c a n d e p r e s s s i m i l a r l y b o t h r a t e s a c c o r d i n g t o a s i m p l e Langmuir model. I n t h i s c a s e , o n e o b s e r v e s no change of RAIB,
the additive acts
l i k e a non s e l e c t i v e p o i s o n . The a d d i v i t e c a n change t h i s r a t i o t h r o u g h b o t h ways :
- change of t h e b / b A
-
change of t h e k /k A
B B
value value
Many a d d i t i v e s w i l l a c t f a v o r a b l y on t h e s e l e c t i v i t y of t h e c a t a l y s t by modifying b o t h terms and a d i s t i n c t i o n between b o t h a c t i o n s i s r a t h e r d i f f i c u l t .
The o b s e r v e d s e l e c t i v i t y of c a t a l y t i c system c a n b e i n f l u e n c e d by s e v e r a l f a c t o r s . These p a r a m e t e r s a r e v e r y o f t e n t h e p r o p e r t i e s o f t h e c a t a l y s t i t s e l f . We c a n m e n t i o n f o r example t h e t y p e of t h e c a r r i e r , t h e n a t u r e of t h e m e t a l ( 5 ) , t h e q u a l i t y of t h e p r e p a r a t i o n
( m e t a l dispersion for instance
( 6 ) ) , the nature
of t h e p r e c u r s o r u s e d i n t h e i m p r e g n a t i o n ( s u l f a t e s , c h l o r i n e o r a l c a l i n e r e s i d u s ) o r a s o l i d a d d i t i v e ( d i f f e r e n t oxydes on t h e c a r r i e r o r a second m e t a l ) The r e a c t i o n m i x t u r e i s a l s o a s o u r c e of m o d i f i c a t o r s . The r e a c t a n t i t s e l f may change t h e c a t a l y t i c s p e c i e s , i t s t r a n s f o r m a t i o n t h r o u g h a p a r a l l e l way c a n produce a p o i s o n o u s p r o d u c t f o r t h e c a t a l y s t o r i t s simple a d s o r p t i o n can r e s t r u c t u r a t e t h e s u rfa ce. The f e e d s t o c k c o n t a i n s v e r y o f t e n i m p u r i t i e s i n s m a l l q u a n t i t y whose a c t i o n
i s s p e c i f i c f o r e a c h compound. A d i s t i n c t i o n i s g e n e r a l l y made between t h r e e t y p e s o f a c t i o n :
The i m p u r i t y p r o d u c e s a s i m p l e i n h i b i t i o n o f t h e a c t i v i t y and a change of s e l e c t i v i t y a s l o n g a s i t i s p r e s e n t i n t h e f e e d s t o c k . When i t s c o n t e n t i s again n u l l the action disappears.
0
The a c t i o n of t h e i m p u r i t y c o n t i n u e s a f t e r i t s d i s p a r i t i o n from t h e
f e e d s t o c k b u t a " r e a c t i v a t i o n " o r " r e g e n e r a t i o n " t r e a t m e n t restores t h e i n i t i a l properties. 0
The a c t i o n of t h e a d d i t i v e i s permanent and no t r e a t m e n t c a n s u p p r e s s
the modification. T h i s d i s t i n c t i o n i s v e r y i m p o r t a n t p r a c t i c a l l y b u t h a s no o b j e c t on a fundam e n t a l b a s i s where o n e h a s o n l y t o examine t h e m o d i f i c a t i n g a c t i o n on t h e a d s o r p t i o n and k i n e t i c c o n s t a n t s . I n t h e f o l l o w i n g t e x t , we w i l l s t u d y i n some d e t a i l s t h e a c t i o n o f c e r t a i n a d d i t i v e s on t h e s e l e c t i v i t y . We e x c l u d e from o u r s u b j e c t t h e r o l e of t h e n a t u r e o f t h e a c t i v e m e t a l and the a c t i o n of t h e support. W e a l s o i g n o r e t h e numerous c a s e s where t h e m o d i f i c a t i o n i s produced by t h e
a d j o n c t i o n o f a second metal t o t h e a c t i v e one.
EFFECTS O F ADDITIVES Rearrangement o f t h e c a t a l y s t by t h e r e a c t i v e The c a t a l y s i s b e i n g a c o n t a c t p r o c e s s , t h e r e a c t i o n needs a n a d s o r p t i o n o f t h e r e a c t i o n on t h e c a t a l y t i c s i t e s . One c o n s i d e r g e n e r a l l y t h a t t h e s i t e " a c t i v a t e s " t h e a d s o r b a t e by m o d i f y i n g i t s s t r u c t u r e o r i t s e n e r g y . I n a n o p p o s i t e d i r e c t i o n , t h e a d s o r b e d s p e c i e s c a n a l s o modify t h e s i t e and t h i s m o d i f i c a t i o n i s h i g h e r f o r t h e s u b s t r a t e more a d s o r b e d . A c o m p l e t e r e c o n s t r u c t i o n of
t h e c a t a l y t i c s u r f a c e h a s been d e m o n s t r a t e d i n
c e r t a i n c a s e s . F o r i n s t a n c e , Burwell and coworkers
( 7 ) show t h a t t h e a c t i v i t y
of p l a t i n u m o n a l u m i n a c a t a l y s t s i n c r e a s e s d u r i n g t h e h y d r o g e n a t i o n o f 3.hexyne.
T h e i r i n t e r p r e t a t i o n o f t h e phenomena i n v o k e s a " s e m i e x t r a c t i v e "
a d s o r p t i o n o f t h e hydrocarbon o n t h e p l a t i n u m . The p l a t i n u m atoms a r e l i f t e d above t h e s u r f a c e c r y s t a l p l a n e s and p r o d u c e h i g h e r a c t i v i t y s i t e s . T h i s e x t r a c t i v e p r o c e s s c a n b e so i n t e n s e t h a t t h e metal atoms a r e e x t r a c t e d by t h e h y d r o c a r b o n s . During t h e h y d r o g e n a t i o n of v i n y l a c e t y l e n e , t h e c a t a l y s t l o s s e s a n i m p o r t a n t p a r t of i t s m e t a l by c o m p l e x a t i o n . The phenomena of r e s t r u c t u r a t i o n i s v e r y d e m o n s t r a t i v e i n t h e b i m e t a l l i c c a t a l y s t s . The a d s o r p t i o n o f a n o r g a n i c s p e c i e s e n r i c h e s t h e s u r f a c e w i t h t h e
m e t a l whose a f f i n i t y f o r t h i s s p e c i e s i s t h e h i g h e s t . I t i s t h e c a s e of t h e Pt-Au,
Pd-Ag,
Pt-Ag a l l o y s . The c h i m i s o r p t i o n of CO i s i n f a v o u r of P t and
P d ( 8 , 9 , 10) a n d t h e c h i m i s o r p t i o n o f oxygen i n f a v o u r o f s i l v e r (11, 1 2 ) .
T h i s r e s t r u c t u r a t i o n of t h e c a t a l y t i c s u r f a c e by t h e r e a c t i v e o c c u r s a l s o i n t h e case o f t h e L i n d l a r c a t a l y s t , w i t h p a l l a d i u m and l e a d
(24). This c a t a l y s t
a f t e r r e d u c t i o n i s formed by a l e a d f i l m c o v e r i n g t h e p a l l a d i u m ( 1 4 ) and a good a c t i v i t y o f s u c h a c a t a l y s t r e q u i r e s a n i n d u c t i o n p e r i o d d u r i n g which t h e
360 acetylenic species extract the palladium atoms. In certains cases, the reaction produces poisons which accumulate on the catalyst and change the catalytic behaviour
:
on the fresh catalyst the reactives
have direct access to the catalytic site and the reaction is kinetically controlled by the diffusion. In this case, the selectivity S becomes
6
(15)
;
the influence of the poison
on selectivity due to the apparition of a diffusion control has been well explicited by de Aguirre (16) and colL and Hegedus and coll. (17). Additives in the reaction mixture The modification of the catalytic sites Can also be produced by foreign compounds present originaly in the feedstock or voluntary added. Many works have been made on CO, amines, sulfur addition and several additions are used industrially (18, 19, 20). Carbon monoxide The figure 3 is obtained from data published by Kemball andcoll. ( 3 ) with the formalism introduced before. The CO promotion of the selectivity is clear. The CO can also depress the isomerization activity of palladium as demonstrated by Furukawa and coll. (21) which have studied the hydrogenation of butadiene to 1.butene and its subsequent isomerization to 2.butenes.
1004
99. P = 1 Atrn
FEED
98.
'
97
FEED
:
9725 %CZH4 275 %CZHZ
d 1
01
-
0.01 % CZH2
Fig.3 INFLUENCE OF CO ON
ACETYLENE HYDROGENATION
361 Nitrogen compounds Selectivation of the catalysts by nitrogen containing compounds has been widely used (see table 2) and has been studied for a long time. One considers generally two ways of action of this aminogroup
:
asimple adsorption competi-
tion or a charge transfer from the free nitrogen doublet towards the metal whose electronic environment is modified. This interaction metal-additives has been examined for the homogeneous and heterogeneous catalysts by Boulinguiez (33). TABLE 2 Effect of nitrogen compounds
Catalyst Palladium
Additive
Quinoline, pyridine Acetylenics Pyridine
Nickel
Reaction
+
Pb(Ac0)
Reference
+ Ethylenics
22,23,24,25,26 27
2
Piperidine Piperidine
28
+
29
Pb (AcO) Palladium
Primary amine
Cyclodiene
+Cyclodecene
30
Nickel, Iron or cobalt arseniate or antimonate
NH OH, amines
Diolefins
+ Monoolefins
31,32
4
The table 3 extracted from his work emphasizes the additive effect on pyridine on the selectivity of hydrogenation of isoprene. The intermediate olefins are subsequently hydrogenated with a substantially decreased rate. This phenomena has been explained by the change of the retrodonation bonding induced by the modification of the electronic character of the metal (34). TABLE 3 Hydrogenation of isoprene - Product repartition
Products
2 M B2
Pyridine
-
+ 2 M B1
-
t
3
M
B1
I C 5
-
+
+
1 0 mn
40 36 30 40 0
20 30 4
25 mn 43 36,5 16 39 0
19 41 585
50 mn
75 mn 39,5 39 3,5 36
41 39 8 36,5
0
0
14
16,5 51 8
20 % isoprene/80 % cyclohexane Reaction : 20 Catalyst : homogeneous and supported nickel
57 11 OC
0.9 MPa
362 S i m i l a r e f f e c t s have been o b s e r v e d by Vasudevan and c o l l . i n t h e hydrogena-
( 3 5 ) . The a d d i t i o n of p i p e r i d i n e
t i o n of 1-butyne on p a l l a d i u m o v e r alumina
d e p r e s s e s t h e h y d r o g e n a t i o n r a t e o f 1 - b u t e n e b u t promotes t h e h y d r o g e n a t i o n of 1-butyne
( f i g u r e 4 ) . T h i s promotion e f f e c t c a n b e i n t e r p r e t e d a s a " l i g a n d
e f f e c t' I . T h i s promoting e f f e c t of t h e h y d r o g e n a t i o n r a t e h a s a l s o been shown on homogeneous n i c k e l and c o b a l t c a t a l y s t
(36) i n t h e h y d r o g e n a t i o n of c y c l o p e n t a d i e n e .
Besides t h e h i g h e r s e l e c t i v i t y t o cyclopentene, t h e hydrogenation r a t e of cyclopentadiene i s s u b s t a n t i a l l y increased.
H2 consumption
T= 20'C
P= E M p o
Cola
. 0 3%
A)
No
PdlAlumino
pipendine
6 ) 0.8cc piperidine in lOcc butyne ILButyne
200
I
I
10
20
30
40 Time (rnn)
Fig 4 INFLUENCE OF PlPERlDlNE ON HYDROGENATION RATE OF 1-BUTYNE AND 1-BUTENE
S u l f u r compounds The name s u l f u r compounds c o v e r s a b i g v a r i e t y of p r o d u c t s a s H S , m e r c a p t a n s , 2 e l e m e n t a l s u l f u r , whose a c t i o n on t h e c a t a l y s t s w i l l be
thiophene, p o l y s u lfid e,
d i f f e r e n t . Only c e r t a i n a s p e c t s have been p r e s e n t e d h e r e . The s u l f u r a d d i t i v e s a r e v e r y o f t e n i m p u r i t i e s of t h e f e e d s t o c k s and i n d u s -
t r i a l c a t a l y s t s a r e d e s i g n e d and s e l e c t e d by t h e i r a b i l i t y t o keep a s u f f i c i e n t a c t i v i t y i n t h e i r presence. Many t i m e s , s u c h compounds a r e v o l u n t a r y added t o o b t a i n a b e t t e r s e l e c t i v i t y of p a r a l l e l o r c o n s e c u t i v e r e a c t i o n s . A s h o r t l i s t of s u c h m o d i f i c a t i o n s i s
g i v e n i n t a b l e 4.
363 TABLE 4 Effect of sulfur compounds
Catalyst
Additive
Reaction
Co and Ni (bulk) H S and thiophene
Ni/A1 0 2 3 Ni/Kieselguhr Ni/A1 S 2 3
Butadiene 'I4 2 Various S compounds Isoprene ?CS
2 Sulfided carrier
Reference
-
additio$ butene 2
37,38
methylbutenes
39
cycloolefin
40
Olefine 1,4 additio Isoprene ) mephylbutene 2
41
Cyclotriene Diene
Pd/A1203
Thiophene
Ni-NiO
Various Scompounds Octyne
Ni S 2 2
H S 2
-
Acetylene
42
octene
43
ethylene
44
The figures 5a and 5b show a very demonstrative example of the influence of thiophene on the hydrogenation selectivity of isoprene
:
decreasing of paraffin
formation and promotion of 1-4 addition. Again the sulfided molecules have two actions. A competition for the metal surface between sulfide and substrate, the adsorption of sulfided species can sometimes be a more or less complete sulfuration of the metal, and an electronic transfer between the sulfur doublet and the metal.
100
75
50
25
0
50
100
150
200
H2 consumption (%)
Fig 5a
Fig. 5a. Hydrogenation of isoprene on Raney nickel without thiophene. P = isopentane
2-1
=
2 methylbutene 1
2-2 = 2 methylbutene 2 3-1 = 3 methylbutene 1
364
75
Raney Nickel = 0.61q
50
25
0
50
100 H2 consumption(%I
Fig.5b
Fig. 5b. Hydrogenation of isoprene on Raney n i c k e l i n presence of thiophene.
0
Coreactif e f f e c t
Solvent e f f e c t s o n hydrogenation r a t e s a r e well known (33, 46) and have been evaluated k i n e t i c a l l y ( 4 7 ) . The a d d i t i v e e f f e c t examined h e r e above can be obtained with c o r e a c t i v e s . The t a b l e 5 p r e s e n t s t h e i n f l u e n c e of p i p e r i d i n e , isoprene and butadiene on t h e hydrogenation r a t e of I-butyne and t h e s e l e c t i v i t y t o butene ( 4 8 ) . TABLE 5
E f f e c t of a d d i t i v e and c o r e a c t i v e on butyne hydrogenation
n heptane Turn over (mol atg-1 S-1 ) 8
9.1
n heptane + 0.8ccpiperidine
isoprene
23.4
23.1
3.1
1.5
bu t a d i ene
20.5
butane formed a t 99 %
18
-
1-butyne conversion 0.3 % Pd/A1 0 Dispersion 60 % 2 3 P = 2 MPa T = 2 0 'C Operating c o n d i t i o n s : Catalyst
Feedstock
:
:
10 c c 1-butyne
+
90 c c s o l v e n t or c o r e a c t i v e
The a c t i o n of isoprene and butadiene i s very s i m i l a r t o t h e a c t i o n of p i p e r i d i n e . The a c t i v i t y of hydrogenation and t h e s e l e c t i v i t y a r e promoted. The Unsaturated hydrocarbons have h e r e t h e r o l e of a l i g a n d i n a s i m i l a r way
365 t o t h e p i p e r i d i n e . T h i s l i g a n d e f f e c t i s known i n homogeneous c a t a l y s i s a n d a p p l i c a t i o n of s u c h a d d i t i v e h a s been p a t e n t e d f o r s o l u b l e and s u p p o r t e d catal y s t s (49). a Other a d d i t i v e s A l o t of o t h e r o r g a n i c and i n o r g a n i c compounds have been u s e d f o r m o d i f i c a -
t i o n of c a t a l y s t s ( t a b l e 6 ) . TABLE 6
E f f e c t of miscallaneous a d d i t i v e s
Catalyst
Additives
Reaction
RU
Phosphorus a c i d / w a t e r
Aromatic
Pd/A1203
C12, N 2 0
Butadiene
RuCl
Reference _ j
cycloolefin
50
1- b u t e n e
21
3 Pd/A1203
B a s i c compound
Aromatic
N methylpyrrolidone
Butadiene p u r i f i c a t i o n
d cycloolefin
Ni
Phosphines
Isoprene
51 52
d methylbutenes
33
S i m i l a r e f f e c t s have been d e m o n s t r a t e d on s u p p o r t e d homogeneous c a t a l y s t s on non c o n v e n t i o n n a l s u p p o r t s ( l i k e n y l o n and r e s i n s , ( 3 4 ) )
.
A q u a n t i f i c a t i o n o f t h e a d d i t i v e s e f f e c t h a s n o t y e t been made e x c e p t b y a
few w o r k e r s l i k e Maurel and c o l l .
( 5 3 ) who d e f i n e a t m x i c i t y i n d e x of p o i s o n s
and examine t h e i r e f f e c t on t h e h y d r o g e n a t i o n and d e u t e r a t i o n o f benzene. 0
Combined e f f e c t s o f s e v e r a l a d d i t i v e s
S e v e r a l m o d i f i c a t i o n e f f e c t s among t h o s e shown h e r e above c a n b e combined on a same c a t a l y s t and g i v e a p o s s i b l e a c t i o n on t h e a c t i v i t y and s e l e c t i v i t y of t h e c a t a l y s t . For i n s t a n c e , t h e c o m p e t i t i v e h y d r o g e n a t i o n of t o l u e n e and benzene h a s been s t u d i e d w i t h s u l f u r , n i t r o g e n and c h l o r i n e compounds i n t h e feed (54). The t a b l e ? a shows t h e i n f l u e n c e of s u l f u r , of n i t r o g e n and o f m i x t u r e s of b o t h , on t h e s e l e c t i v i t y t o l u e n e / b e n z e n e
( R T B ) . The i n c r e a s i n g e f f e c t on t h i s
s e l e c t i v i t y o f 50 ppm of s u l f u r i n p r e s e n c e o f 950 ppm o f n i t r o g e n i s as import a n t as t h e e f f e c t o f 800 ppm of s u l f u r a l o n e . On t h e o t h e r hand,
1000 ppm
n i t r o g e n a l o n e g i v e t h e same RTB a s t h e p l a t i n u m w i t h o u t a d d i t i v e . The t a b l e l b i n d i c a t e s t h e i n f l u e n c e o f n i t r o g e n and c h l o r i n e combined w i t h s u l f u r on t h e a c t i v i t y of h y d r o g e n a t i o n o f t o l u e n e and benzene. The e f f e c t of n i t r o g e n and c h l o r i n e a r e o p p o s i t e when added w i t h s u l f u r . The nitrogen i n c r e a s e s t h e poisoning e f f e c t of s u l f u r while t h e c h l o r i n e has an "antidote" effect. T h e s e b e h a v i o u r s have been i n t e r p r e t e d by a v a r y i n g s u l f u r i z a t i o n e q u i l i b r i u m , t h e e l e c t r o d o n o r compound ( t h e n i t r o g e n ) r e i n f o r c i n g t h e m e t a l - s u l f u r bond and
366 the electroacceptor one (the chlorine) labilizing the same. TABLE ?a Relative reactivities of toluene/benzene on platinum/alumina (RTB) P = 4.5 MPa
T = 300 'C
WH = 8
0.6
0
0 f 1000
(1
50
1.25
50
f
950
1.74
200
1.53
200 +
000
1.83
500
1 .6a
500
f
500
2 .oo
800
1.77
aoo
t
200
2.10
-
1 .ao
1000
-
TABLE ?b Toluene
+
benzene hydrogenation activity on platinum/alumina P = 4.5 MPa
T = 300 'C
Additives
VVH = 8
Rate of hydrogenation toluene + benzene 2 mol./g-lh-' x 10
~
I
l o 0 0 ppm N
500 ppm
S i500
500 ppm
S
+
1
S
500 ppm
ppm N
500 ppm C1
0.14
1.8
CONCLUSION This short review has shown some examples of the numerous possibilities of additives for modifying the activity and selectivity of hydrogenation catalysts. It is obvious that their mechanism of action is a very complex matter. Likely, we may assume that several effects can be produced by a single additive . For example, active site blocking, surface restructuration and electronic effects could be obtained with sulfur on certain metals. We have also to take into account the surface heterogeneity of solid catalyst. Generally speaking, it would be very interesting to increase our knowledge in order to decide if one additive acts on the intrinsic activity or on the reactant adsorbtion or on both. Nevertheless, in some interesting cases,
367 e l e c t r o n i c e f f e c t s have t o b e invoked when b o t h a c t i v i t y and s e l e c t i v i t y a r e i n c r e a s e d a s i t c a n b e s e e n f o r example w i t h some n i t r o g e n compounds i n t h e h y d r o g e n a t i o n o f l . b u t y n e and c y c l o p e n t a d i e n e .
These e f f e c t s are observed
e i t h e r on homogeneous o r s o l i d C a t a l y s t s . They c a n b e e x p l a i n e d b y t h e t o o s t r o n g c o m p l e x a t i o n o f t h e h i g h l y u n s a t u r a t e d h y d r o c a r b o n s . I n t h i s case, t h e e f f e c t of t h e a d d i t i v e , which c a n b e c a l l e d " l i g a n d e f f e c t " i s t o d e c r e a s e t h i s c o m p l e x a t i o n s t r e n g t h and c o n s e q u e n t l y t o enhance a c t i v i t y and s e l e c t i v i t y . The d e c r e a s e of s u l f u r p o i s o n i n g by a d d i n g a second " a n t i d o t e a d d i t i v e " l i k e c h l o r i n e compounds may a l s o b e e x p l a i n e d by a d e c r e a s e o f s u l f u r bounding t o t h e metal. T h i s k i n d of e l e c t r o n i c e f f e c t seems t o u s t h e most p r o m i s i n g d i r e c t i o n t o b e choosen f o r q u a n t i t a t i v e s t u d y of a d d i t i v e s a c t i o n .
I t w i l l p r o v i d e u s one
of t h e most u s e f u l t o o l f o r improving a c t i v i t y and s e l e c t i v i t y o f h y d r o g e n a t i o n catalysts.
REFERENCES J u n g e r s and c o l l . , C i n e t i q u e chimique a p p l i q u & e , Technip Ed., Q980) p . 409. B o i t i a u x , J. Cosyns and S. Vasudevan, s u b m i t t e d f o r p u b l i c a t i o n i n iq p p l i e d C a t a l y s i s . 3 IY.T. Mac Gown, C . Kemball, D. Whan and M.S. S c u r e l l , T r a n s . F a r a d a y S O C . ,
1 J.C. 2 J.P.
73 (1977) 632. 4 Ij. B o u l i n g u i e z , t h e s i s P a r i s , Technip Ed. ( 1 9 7 6 ) . 5 f;.C. Bond, C a t a l y s i s by m e t a l s , Academic P r e s s (1962) P . 2926 J.P. B o i t i a u x , J . Cosyns and S . Vasudevan, T h i r d I n t . Symposium f o r t h e ? r e p a r a t i o n of h e t e r o g e n e o u s c a t a l y s t s , Louvain-la-Neuve ( 1 9 8 2 ) . 98:18 (1976) 5603. 7 3 . H . Kung, R . J . P e l l e t and R . L . Burwell J r , J.A.C.S., S a c h t l e r a n d P . Van d e r P l a n c k , S u r f . S c i . 18 (1969) 62. 8 Y.M.H. 9 i . Bowman, G . J . M . L i p p e t s and W . H . M . S a c h t l e r , J . C a t a . 25 (1972) 360. 10 R. Bowman and W.H.M. S a c h t l e r , J. C a t a . 19 (1970) 127. 11 R.L. Moss and D . H . Thomas, J. C a t a . 8 (1967) 151. 12 R.L. Moss and D . H . Thomas, J. C a t a . 8 (1967) 162. 13 I . d e A g u i r r 6 a n d B. Duque, P r o c e e d i n g s o f t h e I n t . Symposium on t h e r e l a t i o n s between homogeneous and h e t e r o g e n e o u s c a t a l y t i c phenomena, B r u x e l l e s
(1974) 26. 14 H . L i n d l a r , Helv. Chim., Acta 35 (1952) 446, Org. S y n t h . 46 (1966) 89. 15 J . F . Le Page, C a t a l y s e d e c o n t a c t , T e c h n i p Ed. 43. 16 I . d e A g u i r r 6 and B. Duque, P r o c e e d i n g s of t h e I n t . Symposium on t h e r e l a t i o n s between h e t e r o g e n e o u s and homogeneous c a t a l y t i c phenomena, B r u x e l l e s
(1974) 12. 17 18 19 20 21 22 23 24 25 26 27
L o u i s Heqedus and R o b e r t W. Mc Cabe, C a t a l . Rev. S c i . Eng. 23 (1981) 377. Maruzen O i l Company, U.S. P a t e n t 3,674,886. DOW Chemical Company, Dutch P a t e n t 7,115,019. Dow Chemical Company, U . S . P a t e n t 3,634,536. Y a s u h i r o Furukawa, A k i r a Yokogawa, T a k a s h i Yokomizo and Y o u j i Komatsu, B u l l e t i n of t h e J a p a n P e t r o l e u m I n s t i t u t e , 15 (1973) 56. 0. I s l e r , W. Huber, A . Ronco and M. K e f l e r , Helv. Chim., A c t a 30 (1947) 1911. E.N. Marvell and T. L i , S y n t h e s i s 8 (1973) 457. E.N. M a r v e l l , T. Gosink and P . C h u r c h l e y , J. Org. Chem. 37 (1972) 2989. S o k o l " s k a y a , K i n e t . K a t a l . 12 (1971) 525. D . V . S o k o l ' s k i i and P . Gadenov, J z v . Akad. Nauk. S e r . Khim. 20 (1970) 62. H . L i n d l a r , Helv. Chim. A c t a 35 (1952) 446, Org. S y n t h e s i s 46 (1966) 8 9 . L.
368 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
W. O r o s h n i k and A . D . Mebane, J . Amer. Chem. SOC. 76 (1954) 5719. W. O r o s h n i k , G. K a r m a s and A . D . Mebane, J . Amer. CQem. SOC. 74 (1952) 3807. U.O.P. U.S. P a t e n t 3 , 4 3 3 , 8 4 2 . P h i l l i p p s P e t r o l e u m , U.S. P a t e n t 3 , 6 3 7 , 8 7 7 . P h i l l i p p s Petroleum, U . S . P a t e n t 3,636,175. D. B o u l i n g u i e z , T h e s i s P a r i s , T e c h n i p Ed. ( 1 9 7 6 ) . D. Commereuc and G . M a r t i n o , Rev. I n s t . Franr;. du P e t r o l e , 3 0 (1975) 8 9 . J . P . B o i t i a u x , J . Cosyns and S. Vasudevan, t o be p u b l i s h e d . D. Durand, T h e s i s P a r i s ( 1 9 7 4 ) . Y . Okamoto, K. F u k i n o , T. Imanaka and S . T e r a n i s h i , J . C a t a l . 74 (1982) 173. M. George, R . B . Moyes, D. Ramanarov and P . B . W e l l s , J . C a t a l . 52 (1978) 486. K . H . Bourne, P.D. Holmes and R . C . P i t k e t h l y , T h i r d I n t . Cong. on C a t a l y s i s , Amsterdam (1964) P r e p r i n t s P a p e r N o 11, 16. A q u i t a i n e O r g a n i c o , U.S. P a t e n t 3 , 5 7 6 , 8 9 4 . S h e l l O i l , U.S. P a t e n t 4 , 0 7 8 , 0 1 1 . J . Cosyns and J . P . B o i t i a u x , u n p u b l i s h e d r e s u l t s . A . Koppova, V. Z a p l e t a l , V. Ruzicka and J . Sonkup, C o l l e c t . C z e c h o s l . Chem. Commun. 38 (1973) 2466. R . E . R e i t m e i e v and H.W. F l e m i n g , Chem. Eng. P r o g . 54 (1958) 4 8 . J. V e r b o i s , T h e s i s Louvain ( 1 9 7 0 ) . L . Cerveny, A . P r o c h a z k a and V . R u z i c k a , C o l l . C z e c h o s l o v . Chem. Commun. 39 (1974) 2463. A . Lozowski, T h e s i s Louvain ( 1 9 7 3 ) . J . Cosyns, N . T a g u i z a d e h and S . Vasudevan, t o b e p u b l i s h e d . I . F . P . , U.S. P a t e n t 3 , 9 2 2 , 3 1 8 . Toray I n d u s t r i e s , U.S. P a t e n t 4 , 1 9 7 , 4 1 5 . E . I . Dupont d e Nemours, B e l g i s h P a t e n t 782,721. K. Volkamer, K . J . S c h n e i d e r , A . L i n d n e r a n d and D . Bender, E r d o e l und Kohle, E r d g a s - P e t r o c h e m i e v e r e i n i g t m i t Brennstoff-Chemie 34 (1981) 344. R. Maurel and J . B a r b i e r , J . d e c h i m i e p h y s i q u e , 73 (1976) 9 9 5 , 75 (1978) 410. J . Cosyns, J . P . F r a n c k and 2 . Marin G i l , C . R . Acad. S c . P a r i s 287 (1978) 8 5 , 288 (1979) 25.