- Email: [email protected]
Saturated and Unsaturated Ketones Manufactured by Heterogeneous Catalysis
M. Guisnet et al. (Editors), Heterogeneous Catalysis and Fine Chemicaki II @ 1991 Elsevier Science Publishers B.V., Amsterdam
487
SATURATED AND UNSATURATED KETONES MANUFACTURED BY HETEROGENEOUS CATALYSIS
W.
Reith’,
M. Dettnier’,
H. Widdecke‘,
B. F l e i s c h e r ‘
1 RWE-DEA Ah f u e r M i n e r a l o e l und i n e m i e , P.0.Box 1d1420, U ( k e s t tiemany) Technische U n i v e r s i t i t Braunschweig, Hans-Somner-Str. 10, 0 33U0 Braunschweig (West Lermany)
*
-
4130 Moers l
-
SUMMARY A c i d i c i o n exchange r e s i n s a r e used f o r m a n u f a c t u r i n g b o t h b u l k chemicals and f i n e chemicals. The p r e s e n t paper r e l a t e s t o d i f f e r e n t r o u t e s o f p r o d u c i n g methyl i s o b u t y l ketone ( P l I B K ) , methyl i s o p r o p y l k e t o n e (MIK) and methyl i s o propenyl k e t o n e ( M I P K ) u s i n g a palladium-doped i o n exchange r e s i n as a c a t a l y s t . A new process v a r i a n t f o r a l t e r n a t i v e l y m a n u f a c t u r i n g MIPK and MIK w i t h t n e same equipment i s d e l i n e a t e d . INTRODUCTION Since t h e m i d - f i t t i e s s u l f o n a t e d r e s i n s oased on s t y r e n e / d i v i n y l b e n z e n e copolyiners, i n i t i a l l y developed as i o n exchangers m a i n l y t o r w a t e r t r e a t m e n t , nave a l s o been used as s t r o n g l y a c i d i c s o l i d c a t a l y s t s . Witn few exceptions, i n d u s t r i a l a p p l i c a t i o n i n continuous processes i s l i m i t e d t o t h e manufacture o f b u l k chemicals, sucn as Disphenol A, ( m e t h ) d c r y l a t e s , m e t h y l e t h e r s o f brancned o l e f i n s (MTBE, TAME) and secondary a l c o h o l s (IPA, SBA). F o r i n s t a n c e , methyl t e r t - b u t y l e t h e r (MTdE) used w o r l d w i d e as an octane improver i n g a s o l i n e i s produced a t a s t i l l growing g l o b a l c a p a c i t y o f approx. 8 m i l l i o n mtlyr u s i n g s u l f o n a t e d r e s i n s as c a t a l y s t s ( r e f . I ) . HWE-DEA ( f o r m e r Ueutsche Texaco Ab) i s one o f t h e l e a d i n g companies i n t h e development ana commercial a p p l i c a t i o n o f processes u s i n g i o n excnange r e s i n s as a c i d i c c a t a l y s t s . Our e x p e r t i s e comprises p r o d u c t i o n o f b u l k chemicals, sucn as MTBE ( r e f s . 2-31,
i s o p r o p y l a l c o h o l ( r e f s . 2 , 4-5) and s e c - b u t y l
a l c o h o l ( r e f s . 2, 6-7) as w e l l a s manufacture o f low-volume chemicals s o l d a t n i g h e r p r i c e s , sucn as methyl i s o b u t y i ketone, methyl i s o p r o p e n y l Ketone and methyl i s o p r o p y l k e t o n e ( r e f s . 8 , Y-10):
488
fl
CH3-C-CH
Methyl i s o b u t y l ketone
0 CH
ZH
Methyl isopropenyl Ketone
II I
3
f
ZH 1 3 -CH-CH3
MIBK
3
MIPK Z
-C-Z=CH2 0 ctl. II I
3
MIK
CH3-C-CH-iH3
Methyl i s o p r o p y l ketone
1
3
MANUFACTURE OF MIBK MIBK
1,a
s o l v e n t f o r i n k s and lacquers, i s formed oy r e a c t i n g two equiv-
a l e n t s o f acetone ff. v i a i t s i n t e r m e d i a t e s diacetone a l c o h o l oxide
2.
!
2 CtlJ-C-CH3
II
CH3-C-LH
fl
utl
0
->
I
-C-CH 2 1 Ctij
-> CH -C-CH=C-CH 3
I 3 CHJ
5 and m e s i t y l
-> 1
5
4
This process can be performed i n d i f f e r e n t ways: Three-Step Process t o MIBK The c l a s s i c a l r o u t e uses t h r e e steps: p r o d u c t i o n o f
2 using
a s t r o n g base
6, and hydrogenation as a c a t a l y s t , denydration by a c i d i c c a t a l y s i s y i e l d i n g -
w i t h a noble-metal c a t a l y s t s e l e c t i v e l y y i e l d i n g
1.
Two-step Process t o MIBK
I n t h i s v a r i a n t an a c i d i c i o n exchange r e s i n c l i r e c t i y c a t a l y z e s t h e forina6 w i t h i n s i g n i f i c a n t formation o f tion of -
2.
Hydrogenation i s t h e same as i n
t h e three-step process. One-Step Process t o RlBK I n a one-step process a Pd-doped s u l f o n a t e d r e s i n (e.g.
a standard macro-
porous t y p e w i t h 0.1-5 % Pd) c a t a l y z e s o o t h t h e condensation o f ff y i e l d i n g
1
6
and t h e hydrogenation o f ! = t o i i n a s i n g l e r e a c t o r . RWE-DEA has been producing
1for
many y e a r s by t h i s process developed i n t h e i r l a b s and p i l o t p l a n t s .
MANUFACTURE OF MIPK AND M I K MIPK 2 and M I K
2 are
f i n e chemicals used as raw m a t e r i a l s i n t h e p r o d u c t i o n
of dyes, agrochemical s, pharmaceuticals, s p e c i a l t y polymers e t c . A t f i r s t s i g h t s i m i l a r processes as f o r t h e manufacture o f MIBK seem t o be a p p r o p r i a t e . Methyl e t h y l ketone (MLK) 7 r e a c t s w i t h an aqueous s o l u t i o n o f formaldehyde
489
-8 y i e l d i n g genation t o
t h e hydroxyketone
3.
2 that
can be dehydrated t o
H
0 II
CH -Z-CH + CH 0 - > CHJ-C-CH-CH2-OH 3 1 2 L I LH3 CH3 7 -
8 -
4
f o l l o w e d oy hydro-
-> 2 ->
3 -
9 -
One-Step Process t o M I P K / M I K Even triough t n e above r e a c t i o n e q u a t i o n suggests use o f t h e e l e g a n t s i n g l e s t e p process, t h i s v a r i a n t i s n o t a p p l i c a b l e i n t h e case o f t h e M I K s y n t h e s i s . Oue t o unavoidable s i d e r e a c t i o n s t h e c a t a l y s r l i f e t i m e would be v e r y s h o r t r e s u l t i n g i n an i n t o l e r a b l e c o s t i n c r e a s e . MEK
1 nas
f i v e hydrogen dtonis i n a l p n a p o s i t i o n t o t h e c a r b o n y l group. Each
o f them i s a b l e t o r e a c t w i t h formaldehyde t o f o r m n o t o n l y t h e d e s i r e d monon y a r o x y r w t h y l a t e d ltetone b u t a l s o d i - , tri-, t e t r a - and pentahydroxymethylated ketones. These hydroxyketones as w e l l as t h e c o r r e s p o n d i n g u n s a t u r a t e d ones form s o - c a l l e d ' k e t o n e r e s i n s ' oy polycondensation, p o l y a d d i t i o n and p o l y m e r i z a t i o n . Because o f t h e p o l a r i t y o f t h e i o n exchange r e s i n , t h e concent r d t i o n o f w a t e r and formaldehyde, r e f e r r i n g t o IUIEK, i s h i g h e r i n s i d e t h e oeads than i t i s o u t s i d e r e s u l t i n g i n an i n c r e a s e i n s i d e r e a c t i o n s . F u r t h e r more, t r a n s p o r t a t i o n o f t h e ' k e t o n e r e s i n s ' formed i n s i d e i s nindered. Conseq u e n t l y , t h e beads a r e d e s t r u c t e d ( s e e f i g s . 1 and 2 ) which r e s u l t s i n a n i n c r e a s e i n p r e s s u r e drop over t h e r e a c t o r .
E l e c t r o n Scan M i c r o s c o p i c Shot o f C a t a l y s t Beads F i g . I Used C a t a l y s t F i g . 2 Fresh C a t a l y s t
490
The problem i s enhanced during the r e a c t i o n as the i n i t i a l l y homogeneous l i q u i d mixture becomes heterogeneous. This i s i l l u s t r a t e d i n Fig. 3 showing the ternary phase diagram o f t h e feed components MEK/water/formal dehyde w i t h i t s m i s c i b i l i t y gap a t 105 "C/10 bar. The two s t r a i g h t l i n e s mark t h e hypot h e t i c a l mixtures o f 40 % f o r m a l i n w i t h t h e MEK/water azeotrope ( l i n e I ) and a molar 4 : l m i x t u r e o f MEK/formaldehyde w i t h water ( l i n e 11). The l i n e i n t e r section represents t h e composition o f the mixture a t t h e r e a c t o r i n l e t . During the r e a c t i o n t h e MEK concentration decreases s l i g h t l y , whereas the formaldehyde concentration approaches zero. The m i s c i b i l i t y gap widens due t o format i o n o f the nonpolar proaucts
2 and 3.
The r e a c t i o n mixture i n the r e a c t o r
thus r a p i d l y separates i n t o a formaldehyde-poor organic phase and a formaldehyde-rich aqueous phase. The d e s i r e d molar MEK excess thus i s o f f s e t i n the aqueous phase. Since the c a t a l y s t s t i l l has a higher a f f i n i t y f o r t h e aqueous phase, formation o f ketone r e s i n s increases i n s i d e t h e beads. As a r e s u l t o f t h i s unavoidable f o u l i n g the c a t a l y s t l i f e time decreases r a p i d l y . This may be acceptable f o r a cheap c a t a l y s t , b u t i s h i g n l y uneconomic f o r an expensive noble metal doped c a t a l y s t . Iormaldahyda
,7;/5do
0.0
MEK
Fig. 3
line II
0.1
0.3
0.5
0.7
0.9
Phase Diagram (Mass F r a c t i o n ) o f t h e Ternary Feed w i t h M i s c i b i l i t y Gap a t 105 "C/10 bar
Two-step Acid-Catalyzed Process t o MIPK/MIK Since a Pd-doped r e s i n would be t o o expensive even i f the palladium was recovered f o r reloading, a two-step process using an inexpensive r e s i n and subsequent hydrogenation w i t h a comnon c a t a l y s t i s s u i t a b l e f o r t h e rnanufact u r e o f M I K and M I P K (Fig. 4 ) . A molar excess o f MEK (approx. 4 : l ) i s f e d together w i t h an aqueous s o l u t i o n of formaldehyde (approx. 40 X ) t o t h e f i r s t r e a c t o r R-1 c o n t a i n i n g a nondoped r e s i n . Here the same f o u l i n g problem occurs
49 1
besides the desired condensation and dehydration, b u t the c a t a l y s t i s f a r l e s s expensive and can be replaced occasionally. The heterogeneous e f f l u e n t obt a i n e d a f t e r the r e a c t i o n i s separated and the almost formaldehyde-free aqueous phase i s freed from organic compounds i n column C-1. A t t h i s p o i n t o f the process there are two options: t o feed t h e organic phase d i r e c t l y t o the d i s t i l l a t i o n section f i n a l l y y i e l d i n g pure MIPK o r t o l e a d i t t o hydrogenat i o n i n a second reactor R-2 using a comnon Pd c a t a l y s t (e.g.
0.5
-
5 X Pd on
A1203) y i e l d i n g pure MIK. The p u r i f i c a t i o n o f the two crude products i s b a s i c a l l y the same. Surplus MEK i s recovered and i s recycled as an azeotropic mixture w i t h water t o column C-2, while h i g h - b o i l i n g by-products are separated i n column C-3.
hydrogen 7
c-2
waste water
Fig. 4
Two-step Process t o MIPK/MIK
The cheapest c a t a l y s t f o r the f i r s t reactor i s a gel-type sulfonated r e s i n (e.g. Amberlite@IR 12U, Kohm and Haas). The k i n e t i c s i s c o n t r o l l e d by pore d i f f u s i o n as i l l u s t r a t e d i n Fig. 5 showing t h a t the r e a c t i o n r a t e decreases as the c a t a l y s t g r a i n size increases. l.lE-4 c
I a Ec
-E
9.OE-5.-
\8
.-.-
._ E
'a 5
I
7.OE-5.
5.OE-5-
*\*
0-0:
*-*:
loOOC 105OC
A-A:
110%
---•-*-------.
o'o\o__o
+.o -.3.OE-5,::
Fig. 5
-
: . . : : : .
0 :
:
: : : : : . :
~.
.
~
i0
Reaction Rate as a Function o f C a t a l y s t Grain Size
492
Using macroporous i o n exchange r e s i n s t h e e f f i c i e n c y o f t h e a c t i v e s u l f o n i c a c i d groups i s s l i g h t l y improved. When comparing a comnercial g e l - t y p e i o n exchange r e s i n and a macroporous one (Lewatit@SPC 1U8, Bayer) manufactured w i t h t h e same amount of divinylbenzene, t h e r e a c t i o n r a t e , r e f e r r i n g t o t h e amount o f acid, i s h i g h e r w i t h a macroporous r e s i n ( c f . Table 1 ) . The s t a r t i n g mater i a l s may d i f f u s e unhindered through t h e permanent pores and t h e t r a n s p o r t a t i o n d i s t a n c e through t h e gel phase i s s h o r t e r . A t a h i g h e r c r o s s l i n k i n g degree t h e r e a c t i o n i n t h e gel phases i s repressed. Therefore, Lewatit@SPC 118 and A m t ~ e r l y s t @ l Sa t t a i n o n l y slow r a t e s . Using a surface-sulfonated i o n exchange r e s i n ( r e f s . 11-12],
optimum acces-
s i b i l i t y o f t h e a c t i v e groups which a r e almost e x c l u s i v e l y l o c a t e d a t t h e i n n e r surface o f t h e m i c r o p a r t i c l e s i s a t t a i n e d . The measured r e a c t i o n r a t e (see Table 1 ) i s about ten times h i g h e r than t h a t o f t h e i d e n t i c a l l y cross1 inked Lewati t @ S P C 118. However, when u t i l i z e d on a cormnercial scale, p r i m a r i l y t h e r e a c t i o n r a t e s , r e f e r r i n g t o c a t a l y s t q u a n t i t y o r b u l k volume, a r e i m p o r t a n t because they determine r e a c t o r s i z e and amount o f c a t a l y s t r e q u i r e d . R e f e r r i n g t h e r e a c t i o n r a t e i n t a b l e 1 t o one gram o f r e s i n , t h e s u r f a c e - s u l f o n a t e d i o n exchange r e s i n F 027 i s t h e l e a s t e f f i c i e n t because t h e g e l areas do n o t c o n t a i n any s u l f o n i c a c i d groups. The o t h e r f o u r r e s i n s , however, a r e q u i t e s i m i l a r : they a r e homogeneous and almost completely s u l f o n a t e d . Macroporous and surfaces u l f o n a t e d r e s i n s a r e h i g h e r p r i c e d , b u t n o t more e f f i c i e n t i n comnercial application. TABLE 1 Keaction r a t e s a t t a i n e d w i t h d i f f e r e n t r e s i n s
( T = 105 "C; MEK:HCHO = 4 : l ; F o r m a l i n 20 wt.%) Resin
D i v i n y l benzene
u u a n t i ty
m o l h i n meq
'HCHO
molhin g
120
8
b.3 X
3.1
SPZ 108
8
7.0
3.5
SPC 118
18
3.7
1.6
Amberlyst 15
20
2.8
1.4
F 027
18
IR
38.7 x
1.0
w4
493
New Base-Catalyzed Two-step Process t o M I P K / M I K Besides c a t a l y s t f o u l i n g , t n e g r e a t e s t disadvantage when u t i l i z i n g t h e two processes d e s c r i b e d b e f o r e i s t h e energy-consuming r e c o v e r y o f u n r e a c t e d MEK f r o m M I P K o r ivlIK t h e b o i l i n g p o i n t s o f which a r e c l o s e t o t h a t o f MEK. To overcome b o t h c a t a l y s t f o u l i n g and s e p a r a t i o n d i f f i c u l t i e s a new two-step process has been developed ( c f . F i g . 6 ) : i n r e a c t o r R-1
2,
NaOH as a homogeneous c a t a l y s t y i e l d i n g
L
reacts with
wnich excess 7 can e a s i l y be removed by d i s t i l l a t i o n i n tower C-1. second s t e p
2
2
using
a h i g h - b o i l i n g interiliediate from I n the
i s f e d t o a second r e a c t o r (K-2) c o n t a i n i n g t h e same Pd-doped
a c i d i c exchange r e s i n used i n t h e one-step process f o r h I B K manufacture. Depending on m a r k e t requirements, t h e o u t p u t o f
2 and 3 can
be v a r i e d by
opening o r c l o s i n g t h e hydrogen v a l v e on t h e second r e a c t o r .
I
I
hydrogen
New Base-Catalyzed Two-step Process t o rvlIPK/ivllK
Fig. o
dust-in-time production i s essential, p a r t i c u l a r l y f o r t n e unsaturated ketone
2,
because d u r i n g s t o r a g e a t 2U
OL
the content o f
2 in
the finished
p r o d u c t decreases by (1.4 % p e r day due t o CyClOdimeriZatlOn as shown i n f i g .
0
MIP
0
DMIP
2 -
Fig. 7
10 -
Z y c l o d i m e r i z a t i o n o t IbIIPK
7.
494
Hydroxymethylation o f
I
to
2 in
t h e f i r s t r e a c t o r i s very f a s t a t 40 "C.
In
p r i n c i p l e , a s t r o n g l y b a s i c i o n exchange r e s i n may be used as a s o l i d catal y s t , b u t as expected t h e c a t a l y s t f a i l e d i n t e s t r u n s due t o i n a c t i v a t i o n by f o r m i c a c i d produced by Cannizarro r e a c t i o n . 2 CH20
-> CH30H + HCOOH
CONCLUSION The b e s t way t o a l t e r n a t i v e l y manufacture MIPK and M I K i n t h e same equipment i s the combination o f a hanogeneous and a heterogeneous c a t a l y t i c step.
No c a t a l y s t f o u l i n g occurs, MEK recovery i s easy and cheap and p l a n t f l e x i b i l i t y i s high. REFERENCES 1 2 3 4 5
6 7 8
9
10 11 12
D. Rohe, Chemische I n d u s t r i e 4 (1990) bU-63 M. P r e z e l j , Hydrocarbon Processing 9 (1987) 68-70 Deutsche Texaco AG, DE 3322753 Deutsche Texaco AG, DE 2233967
Petrochemical Handbook '89, Hydrocarbon Processing 11 (1989) 111 Deutsche Texaco AG, DE 3040997 M. P r e z e l j , W. Koog, M. Dettmer, Hydrocarbon Processing 11 (1988) 75-78 Rheinpreussen AG, UE 1260454 Rheinpreussen AG, DE 1193931 Rheinpreussen AG, DE 1198814 U. Haupt, PhD Thesis, Technical U n i v e r s i t y o f Braunschweig (198b) 6 . Halim, MS Thesis, Technical U n i v e r s i t y o f Braunschweig (1988)
487
SATURATED AND UNSATURATED KETONES MANUFACTURED BY HETEROGENEOUS CATALYSIS
W.
Reith’,
M. Dettnier’,
H. Widdecke‘,
B. F l e i s c h e r ‘
1 RWE-DEA Ah f u e r M i n e r a l o e l und i n e m i e , P.0.Box 1d1420, U ( k e s t tiemany) Technische U n i v e r s i t i t Braunschweig, Hans-Somner-Str. 10, 0 33U0 Braunschweig (West Lermany)
*
-
4130 Moers l
-
SUMMARY A c i d i c i o n exchange r e s i n s a r e used f o r m a n u f a c t u r i n g b o t h b u l k chemicals and f i n e chemicals. The p r e s e n t paper r e l a t e s t o d i f f e r e n t r o u t e s o f p r o d u c i n g methyl i s o b u t y l ketone ( P l I B K ) , methyl i s o p r o p y l k e t o n e (MIK) and methyl i s o propenyl k e t o n e ( M I P K ) u s i n g a palladium-doped i o n exchange r e s i n as a c a t a l y s t . A new process v a r i a n t f o r a l t e r n a t i v e l y m a n u f a c t u r i n g MIPK and MIK w i t h t n e same equipment i s d e l i n e a t e d . INTRODUCTION Since t h e m i d - f i t t i e s s u l f o n a t e d r e s i n s oased on s t y r e n e / d i v i n y l b e n z e n e copolyiners, i n i t i a l l y developed as i o n exchangers m a i n l y t o r w a t e r t r e a t m e n t , nave a l s o been used as s t r o n g l y a c i d i c s o l i d c a t a l y s t s . Witn few exceptions, i n d u s t r i a l a p p l i c a t i o n i n continuous processes i s l i m i t e d t o t h e manufacture o f b u l k chemicals, sucn as Disphenol A, ( m e t h ) d c r y l a t e s , m e t h y l e t h e r s o f brancned o l e f i n s (MTBE, TAME) and secondary a l c o h o l s (IPA, SBA). F o r i n s t a n c e , methyl t e r t - b u t y l e t h e r (MTdE) used w o r l d w i d e as an octane improver i n g a s o l i n e i s produced a t a s t i l l growing g l o b a l c a p a c i t y o f approx. 8 m i l l i o n mtlyr u s i n g s u l f o n a t e d r e s i n s as c a t a l y s t s ( r e f . I ) . HWE-DEA ( f o r m e r Ueutsche Texaco Ab) i s one o f t h e l e a d i n g companies i n t h e development ana commercial a p p l i c a t i o n o f processes u s i n g i o n excnange r e s i n s as a c i d i c c a t a l y s t s . Our e x p e r t i s e comprises p r o d u c t i o n o f b u l k chemicals, sucn as MTBE ( r e f s . 2-31,
i s o p r o p y l a l c o h o l ( r e f s . 2 , 4-5) and s e c - b u t y l
a l c o h o l ( r e f s . 2, 6-7) as w e l l a s manufacture o f low-volume chemicals s o l d a t n i g h e r p r i c e s , sucn as methyl i s o b u t y i ketone, methyl i s o p r o p e n y l Ketone and methyl i s o p r o p y l k e t o n e ( r e f s . 8 , Y-10):
488
fl
CH3-C-CH
Methyl i s o b u t y l ketone
0 CH
ZH
Methyl isopropenyl Ketone
II I
3
f
ZH 1 3 -CH-CH3
MIBK
3
MIPK Z
-C-Z=CH2 0 ctl. II I
3
MIK
CH3-C-CH-iH3
Methyl i s o p r o p y l ketone
1
3
MANUFACTURE OF MIBK MIBK
1,a
s o l v e n t f o r i n k s and lacquers, i s formed oy r e a c t i n g two equiv-
a l e n t s o f acetone ff. v i a i t s i n t e r m e d i a t e s diacetone a l c o h o l oxide
2.
!
2 CtlJ-C-CH3
II
CH3-C-LH
fl
utl
0
->
I
-C-CH 2 1 Ctij
-> CH -C-CH=C-CH 3
I 3 CHJ
5 and m e s i t y l
-> 1
5
4
This process can be performed i n d i f f e r e n t ways: Three-Step Process t o MIBK The c l a s s i c a l r o u t e uses t h r e e steps: p r o d u c t i o n o f
2 using
a s t r o n g base
6, and hydrogenation as a c a t a l y s t , denydration by a c i d i c c a t a l y s i s y i e l d i n g -
w i t h a noble-metal c a t a l y s t s e l e c t i v e l y y i e l d i n g
1.
Two-step Process t o MIBK
I n t h i s v a r i a n t an a c i d i c i o n exchange r e s i n c l i r e c t i y c a t a l y z e s t h e forina6 w i t h i n s i g n i f i c a n t formation o f tion of -
2.
Hydrogenation i s t h e same as i n
t h e three-step process. One-Step Process t o RlBK I n a one-step process a Pd-doped s u l f o n a t e d r e s i n (e.g.
a standard macro-
porous t y p e w i t h 0.1-5 % Pd) c a t a l y z e s o o t h t h e condensation o f ff y i e l d i n g
1
6
and t h e hydrogenation o f ! = t o i i n a s i n g l e r e a c t o r . RWE-DEA has been producing
1for
many y e a r s by t h i s process developed i n t h e i r l a b s and p i l o t p l a n t s .
MANUFACTURE OF MIPK AND M I K MIPK 2 and M I K
2 are
f i n e chemicals used as raw m a t e r i a l s i n t h e p r o d u c t i o n
of dyes, agrochemical s, pharmaceuticals, s p e c i a l t y polymers e t c . A t f i r s t s i g h t s i m i l a r processes as f o r t h e manufacture o f MIBK seem t o be a p p r o p r i a t e . Methyl e t h y l ketone (MLK) 7 r e a c t s w i t h an aqueous s o l u t i o n o f formaldehyde
489
-8 y i e l d i n g genation t o
t h e hydroxyketone
3.
2 that
can be dehydrated t o
H
0 II
CH -Z-CH + CH 0 - > CHJ-C-CH-CH2-OH 3 1 2 L I LH3 CH3 7 -
8 -
4
f o l l o w e d oy hydro-
-> 2 ->
3 -
9 -
One-Step Process t o M I P K / M I K Even triough t n e above r e a c t i o n e q u a t i o n suggests use o f t h e e l e g a n t s i n g l e s t e p process, t h i s v a r i a n t i s n o t a p p l i c a b l e i n t h e case o f t h e M I K s y n t h e s i s . Oue t o unavoidable s i d e r e a c t i o n s t h e c a t a l y s r l i f e t i m e would be v e r y s h o r t r e s u l t i n g i n an i n t o l e r a b l e c o s t i n c r e a s e . MEK
1 nas
f i v e hydrogen dtonis i n a l p n a p o s i t i o n t o t h e c a r b o n y l group. Each
o f them i s a b l e t o r e a c t w i t h formaldehyde t o f o r m n o t o n l y t h e d e s i r e d monon y a r o x y r w t h y l a t e d ltetone b u t a l s o d i - , tri-, t e t r a - and pentahydroxymethylated ketones. These hydroxyketones as w e l l as t h e c o r r e s p o n d i n g u n s a t u r a t e d ones form s o - c a l l e d ' k e t o n e r e s i n s ' oy polycondensation, p o l y a d d i t i o n and p o l y m e r i z a t i o n . Because o f t h e p o l a r i t y o f t h e i o n exchange r e s i n , t h e concent r d t i o n o f w a t e r and formaldehyde, r e f e r r i n g t o IUIEK, i s h i g h e r i n s i d e t h e oeads than i t i s o u t s i d e r e s u l t i n g i n an i n c r e a s e i n s i d e r e a c t i o n s . F u r t h e r more, t r a n s p o r t a t i o n o f t h e ' k e t o n e r e s i n s ' formed i n s i d e i s nindered. Conseq u e n t l y , t h e beads a r e d e s t r u c t e d ( s e e f i g s . 1 and 2 ) which r e s u l t s i n a n i n c r e a s e i n p r e s s u r e drop over t h e r e a c t o r .
E l e c t r o n Scan M i c r o s c o p i c Shot o f C a t a l y s t Beads F i g . I Used C a t a l y s t F i g . 2 Fresh C a t a l y s t
490
The problem i s enhanced during the r e a c t i o n as the i n i t i a l l y homogeneous l i q u i d mixture becomes heterogeneous. This i s i l l u s t r a t e d i n Fig. 3 showing the ternary phase diagram o f t h e feed components MEK/water/formal dehyde w i t h i t s m i s c i b i l i t y gap a t 105 "C/10 bar. The two s t r a i g h t l i n e s mark t h e hypot h e t i c a l mixtures o f 40 % f o r m a l i n w i t h t h e MEK/water azeotrope ( l i n e I ) and a molar 4 : l m i x t u r e o f MEK/formaldehyde w i t h water ( l i n e 11). The l i n e i n t e r section represents t h e composition o f the mixture a t t h e r e a c t o r i n l e t . During the r e a c t i o n t h e MEK concentration decreases s l i g h t l y , whereas the formaldehyde concentration approaches zero. The m i s c i b i l i t y gap widens due t o format i o n o f the nonpolar proaucts
2 and 3.
The r e a c t i o n mixture i n the r e a c t o r
thus r a p i d l y separates i n t o a formaldehyde-poor organic phase and a formaldehyde-rich aqueous phase. The d e s i r e d molar MEK excess thus i s o f f s e t i n the aqueous phase. Since the c a t a l y s t s t i l l has a higher a f f i n i t y f o r t h e aqueous phase, formation o f ketone r e s i n s increases i n s i d e t h e beads. As a r e s u l t o f t h i s unavoidable f o u l i n g the c a t a l y s t l i f e time decreases r a p i d l y . This may be acceptable f o r a cheap c a t a l y s t , b u t i s h i g n l y uneconomic f o r an expensive noble metal doped c a t a l y s t . Iormaldahyda
,7;/5do
0.0
MEK
Fig. 3
line II
0.1
0.3
0.5
0.7
0.9
Phase Diagram (Mass F r a c t i o n ) o f t h e Ternary Feed w i t h M i s c i b i l i t y Gap a t 105 "C/10 bar
Two-step Acid-Catalyzed Process t o MIPK/MIK Since a Pd-doped r e s i n would be t o o expensive even i f the palladium was recovered f o r reloading, a two-step process using an inexpensive r e s i n and subsequent hydrogenation w i t h a comnon c a t a l y s t i s s u i t a b l e f o r t h e rnanufact u r e o f M I K and M I P K (Fig. 4 ) . A molar excess o f MEK (approx. 4 : l ) i s f e d together w i t h an aqueous s o l u t i o n of formaldehyde (approx. 40 X ) t o t h e f i r s t r e a c t o r R-1 c o n t a i n i n g a nondoped r e s i n . Here the same f o u l i n g problem occurs
49 1
besides the desired condensation and dehydration, b u t the c a t a l y s t i s f a r l e s s expensive and can be replaced occasionally. The heterogeneous e f f l u e n t obt a i n e d a f t e r the r e a c t i o n i s separated and the almost formaldehyde-free aqueous phase i s freed from organic compounds i n column C-1. A t t h i s p o i n t o f the process there are two options: t o feed t h e organic phase d i r e c t l y t o the d i s t i l l a t i o n section f i n a l l y y i e l d i n g pure MIPK o r t o l e a d i t t o hydrogenat i o n i n a second reactor R-2 using a comnon Pd c a t a l y s t (e.g.
0.5
-
5 X Pd on
A1203) y i e l d i n g pure MIK. The p u r i f i c a t i o n o f the two crude products i s b a s i c a l l y the same. Surplus MEK i s recovered and i s recycled as an azeotropic mixture w i t h water t o column C-2, while h i g h - b o i l i n g by-products are separated i n column C-3.
hydrogen 7
c-2
waste water
Fig. 4
Two-step Process t o MIPK/MIK
The cheapest c a t a l y s t f o r the f i r s t reactor i s a gel-type sulfonated r e s i n (e.g. Amberlite@IR 12U, Kohm and Haas). The k i n e t i c s i s c o n t r o l l e d by pore d i f f u s i o n as i l l u s t r a t e d i n Fig. 5 showing t h a t the r e a c t i o n r a t e decreases as the c a t a l y s t g r a i n size increases. l.lE-4 c
I a Ec
-E
9.OE-5.-
\8
.-.-
._ E
'a 5
I
7.OE-5.
5.OE-5-
*\*
0-0:
*-*:
loOOC 105OC
A-A:
110%
---•-*-------.
o'o\o__o
+.o -.3.OE-5,::
Fig. 5
-
: . . : : : .
0 :
:
: : : : : . :
~.
.
~
i0
Reaction Rate as a Function o f C a t a l y s t Grain Size
492
Using macroporous i o n exchange r e s i n s t h e e f f i c i e n c y o f t h e a c t i v e s u l f o n i c a c i d groups i s s l i g h t l y improved. When comparing a comnercial g e l - t y p e i o n exchange r e s i n and a macroporous one (Lewatit@SPC 1U8, Bayer) manufactured w i t h t h e same amount of divinylbenzene, t h e r e a c t i o n r a t e , r e f e r r i n g t o t h e amount o f acid, i s h i g h e r w i t h a macroporous r e s i n ( c f . Table 1 ) . The s t a r t i n g mater i a l s may d i f f u s e unhindered through t h e permanent pores and t h e t r a n s p o r t a t i o n d i s t a n c e through t h e gel phase i s s h o r t e r . A t a h i g h e r c r o s s l i n k i n g degree t h e r e a c t i o n i n t h e gel phases i s repressed. Therefore, Lewatit@SPC 118 and A m t ~ e r l y s t @ l Sa t t a i n o n l y slow r a t e s . Using a surface-sulfonated i o n exchange r e s i n ( r e f s . 11-12],
optimum acces-
s i b i l i t y o f t h e a c t i v e groups which a r e almost e x c l u s i v e l y l o c a t e d a t t h e i n n e r surface o f t h e m i c r o p a r t i c l e s i s a t t a i n e d . The measured r e a c t i o n r a t e (see Table 1 ) i s about ten times h i g h e r than t h a t o f t h e i d e n t i c a l l y cross1 inked Lewati t @ S P C 118. However, when u t i l i z e d on a cormnercial scale, p r i m a r i l y t h e r e a c t i o n r a t e s , r e f e r r i n g t o c a t a l y s t q u a n t i t y o r b u l k volume, a r e i m p o r t a n t because they determine r e a c t o r s i z e and amount o f c a t a l y s t r e q u i r e d . R e f e r r i n g t h e r e a c t i o n r a t e i n t a b l e 1 t o one gram o f r e s i n , t h e s u r f a c e - s u l f o n a t e d i o n exchange r e s i n F 027 i s t h e l e a s t e f f i c i e n t because t h e g e l areas do n o t c o n t a i n any s u l f o n i c a c i d groups. The o t h e r f o u r r e s i n s , however, a r e q u i t e s i m i l a r : they a r e homogeneous and almost completely s u l f o n a t e d . Macroporous and surfaces u l f o n a t e d r e s i n s a r e h i g h e r p r i c e d , b u t n o t more e f f i c i e n t i n comnercial application. TABLE 1 Keaction r a t e s a t t a i n e d w i t h d i f f e r e n t r e s i n s
( T = 105 "C; MEK:HCHO = 4 : l ; F o r m a l i n 20 wt.%) Resin
D i v i n y l benzene
u u a n t i ty
m o l h i n meq
'HCHO
molhin g
120
8
b.3 X
3.1
SPZ 108
8
7.0
3.5
SPC 118
18
3.7
1.6
Amberlyst 15
20
2.8
1.4
F 027
18
IR
38.7 x
1.0
w4
493
New Base-Catalyzed Two-step Process t o M I P K / M I K Besides c a t a l y s t f o u l i n g , t n e g r e a t e s t disadvantage when u t i l i z i n g t h e two processes d e s c r i b e d b e f o r e i s t h e energy-consuming r e c o v e r y o f u n r e a c t e d MEK f r o m M I P K o r ivlIK t h e b o i l i n g p o i n t s o f which a r e c l o s e t o t h a t o f MEK. To overcome b o t h c a t a l y s t f o u l i n g and s e p a r a t i o n d i f f i c u l t i e s a new two-step process has been developed ( c f . F i g . 6 ) : i n r e a c t o r R-1
2,
NaOH as a homogeneous c a t a l y s t y i e l d i n g
L
reacts with
wnich excess 7 can e a s i l y be removed by d i s t i l l a t i o n i n tower C-1. second s t e p
2
2
using
a h i g h - b o i l i n g interiliediate from I n the
i s f e d t o a second r e a c t o r (K-2) c o n t a i n i n g t h e same Pd-doped
a c i d i c exchange r e s i n used i n t h e one-step process f o r h I B K manufacture. Depending on m a r k e t requirements, t h e o u t p u t o f
2 and 3 can
be v a r i e d by
opening o r c l o s i n g t h e hydrogen v a l v e on t h e second r e a c t o r .
I
I
hydrogen
New Base-Catalyzed Two-step Process t o rvlIPK/ivllK
Fig. o
dust-in-time production i s essential, p a r t i c u l a r l y f o r t n e unsaturated ketone
2,
because d u r i n g s t o r a g e a t 2U
OL
the content o f
2 in
the finished
p r o d u c t decreases by (1.4 % p e r day due t o CyClOdimeriZatlOn as shown i n f i g .
0
MIP
0
DMIP
2 -
Fig. 7
10 -
Z y c l o d i m e r i z a t i o n o t IbIIPK
7.
494
Hydroxymethylation o f
I
to
2 in
t h e f i r s t r e a c t o r i s very f a s t a t 40 "C.
In
p r i n c i p l e , a s t r o n g l y b a s i c i o n exchange r e s i n may be used as a s o l i d catal y s t , b u t as expected t h e c a t a l y s t f a i l e d i n t e s t r u n s due t o i n a c t i v a t i o n by f o r m i c a c i d produced by Cannizarro r e a c t i o n . 2 CH20
-> CH30H + HCOOH
CONCLUSION The b e s t way t o a l t e r n a t i v e l y manufacture MIPK and M I K i n t h e same equipment i s the combination o f a hanogeneous and a heterogeneous c a t a l y t i c step.
No c a t a l y s t f o u l i n g occurs, MEK recovery i s easy and cheap and p l a n t f l e x i b i l i t y i s high. REFERENCES 1 2 3 4 5
6 7 8
9
10 11 12
D. Rohe, Chemische I n d u s t r i e 4 (1990) bU-63 M. P r e z e l j , Hydrocarbon Processing 9 (1987) 68-70 Deutsche Texaco AG, DE 3322753 Deutsche Texaco AG, DE 2233967
Petrochemical Handbook '89, Hydrocarbon Processing 11 (1989) 111 Deutsche Texaco AG, DE 3040997 M. P r e z e l j , W. Koog, M. Dettmer, Hydrocarbon Processing 11 (1988) 75-78 Rheinpreussen AG, UE 1260454 Rheinpreussen AG, DE 1193931 Rheinpreussen AG, DE 1198814 U. Haupt, PhD Thesis, Technical U n i v e r s i t y o f Braunschweig (198b) 6 . Halim, MS Thesis, Technical U n i v e r s i t y o f Braunschweig (1988)