Proceso de Hidrogenacion New

6
343 BIODEGRADATION OF NONIONIC SURFACTANTS TABLE IV Effect of Influent Concentration on Effluent Level Level in plant effluent Nonionic Influent: 5 mg/L Influent: 25 mg/L 7 EO 0.14 0.15 11 EO 0.15 0.10 15 EO 0.21 0.31 20 EO 0.34 0.62 Control plant (sewage only) 0.33 0.11 TABLE V Levels of Nonlo nic on A ctivated Sludge (Influent Concentration = 25 mg/L) Nonionic % Nonionic on dried solids 7 EO 0.28 11 EO 0.29 15 EO 0.24 20 EO 0.25 Control plant 0,29 TABLE VI Polyethylene Glycol Levels in Plant Effluents Influent "PEG" Effluent "PEG" Nonionic (nag/L) (mg/L) % Removal 11 EO 19.8 0.77 96.0 15 EO 20.9 2.61 88.0 20 EO 21.8 2.45 89.0 The above discussion refers only to the levels of primary biodegradation since, throughout, the analysis was made using the Wickbold method which only measures intact nonionic. To obtain some indication of the level of ultimate biodegradation, the polyglycol intermediates in the plant effluents were determined by the HBr fission method des- cribed by Tobin et al. (3). This technique determines the total -OCH2 "CH2- functional groups present in the sample. The results obtained are given in Table VI. The results clearly dem onstrate that a large proportion of the PEG-like intermediates are removed during treatment and show that alcohol ethoxylates undergo extensive ulti- mate biodegradation during sewage treatment. In contrast, Tobin et al. (3) found only ca. 25% ' PEG ' degradation when testing Dobanol 9E0 in the OECD con- firmatory test. The rather low activity of sludges grown on synthetic wastes compared with the highly active bio- mass produced from domestic sewage is the most probable explanation for the discrepancy. ACKNOWLEDGMENTS and J.T. Garrigan. T.R. Williams provided technical assistance. REFERENCES 1. Wickbold, R., Tenside Deterg. 9:173 (1972). 2. Birch, R.R., Presentation at the XIII Jornadas del Com ite Espanol de la Detergencia. 3. Tobin, R.S.F.I. Onuska, B.G. Brownlee, D.I[.I. Anthony and M.E. Comba, Water Res. t0:529 (1976). 4. Rich, L.G., Environmental Systems Engineering, McGraw Hill Inc., New York. Manufacture of Fatty Alcohols Based on Natural Fats and Oils UDO R. KREUTZER, Henkel KGaA, Postfach 1100, D-4000 Dusseldorf 1, West Germany ABSTRACT The present worldwide capacity of fatty alcohols is ca. 1.0 million metric tons per year. About 60% of this capacity is based on petro- chemical feedstocks, 40% on natural fats and oils. Three basic do- minating commercial-scale processes are used to manufacture fatty alcohols: the Ziegler process and the Oxo synthesis starting from petrochemical feedstocks, and the high-pressure hydrogenation of natural fatty acids and esters. Basically, the high-pressure hydro- genation can be used with triglycerides, fatty acids or fatty acid esters as feedstock. The direct hydrogenation of fats and oils has not been developed to a commercial-scale process, mainly because it was not possible to prevent decomposition of the valuable byproduct glycerol. Conversion of fatty acids into fatty alcohols by catalytic hydrogenation without preesterification requires corrosion-resistant materials of construction and acid-resistant catalysts. Required reaction temperatures are higher, resulting in a higher hydrocarbon content. The majority of fatty, alcohol plants based on natural fats and oils use methyl esters as feedstock. These can be made either by esterification of fatty acids or by-transesterification of triglycerides. For catalytic high-pressure hydrogenation of methyl esters to fatty alcohols, several process options have been developed. The bawic distinguishing feature is the catalyst application either in a fixed bed arrangement or suspended in the methyl ester feed. INTRODUCTION Fatty alcohols, particularly the detergent range C12 and higher alcohols, have become an important basic material for a host of derivatives and applications. Today, in the Western hemisphere, the commercial production of fatty alcohols is based on three different process alternatives: the high-pressure hydrogenation of fatty acids and esters, the Ziegler synthesis, and the Oxo synthesis. The Ziegler and Oxo processes start from petrochem- ical feedstocks producing synthetic alcohols, whereas natural fats and oils are the raw materials for the hydro- genation of fatty acids and esters to natural alcohols (1). The present world capacity of natural and synthetic fatty alcohols is ca. 1.0 million metric tons/year (Table I). A regional breakdown of the world capacity into natural and synthetic fatty alcohols shows that in the USA the bulk of fatty alcohols is of petrochemical origin, whereas in Europe more than 60% of the total volume is made from natural fats and oils. Worldwide, ca. 60% of the fatty alcohol capacity is based on petrochemical feedstocks and JAOCS, vol. 61, no. 2 (February 1984)

Transcript of Proceso de Hidrogenacion New

8/8/2019 Proceso de Hidrogenacion New

http://slidepdf.com/reader/full/proceso-de-hidrogenacion-new 1/6

343

B I O D E G R A D A T I O N O F N O N I O N IC S U R F A C T A N T S

T A B L E I V

E f f e c t o f I n f l u e n t C o n c e n t r a t i o n o n E f f l u e n t L e v e l

Lev e l in p lan t e f f lu en tN o n i o n i c I n f l u e nt : 5 m g / L I n f l u e n t : 2 5 m g / L

7 EO 0 .1 4 0 .1 5

11 EO 0.15 0 .1015 EO 0.21 0 .312 0 EO 0 .3 4 0 .6 2

Co n t ro l p lan t ( s ewag e o n ly ) 0 .3 3 0 .1 1

T A B L E V

Lev e ls o f No n lo n ic o n A c t iv a ted Slu d g e( I n f l u e n t C o n c e n t r a t i o n = 2 5 m g / L )

No n io n ic % No n io n ic o n d r ied so l id s

7 EO 0 .2 81 1 EO 0 .2 91 5 EO 0 .2 42 0 EO 0 .2 5

Co n t ro l p lan t 0 ,2 9

T A B L E V I

Po ly e th y len e Gly co l Lev e ls in P lan t E f f l u e n t s

I n f lu e n t " P E G " E f f lu e n t " P E G "No n io n ic (n ag /L) (mg /L) % Remo v a l

11 EO 19.8 0 . 7 7 96.015 EO 20.9 2 .61 88.02 0 EO 2 1 .8 2 .4 5 8 9 .0

T h e a b o v e d i s c u s s i o n r e f e r s o n l y t o t h e l e v e ls o f p r i m a r y

b i o d e g r a d a t i o n s i n ce , t h r o u g h o u t , t h e a n a ly s i s w a s m a d e

u s i ng t h e W i c k b o l d m e t h o d w h i c h o n l y m e a s u r es i n t a c t

n o n i o n i c . T o o b t a i n s o m e i n d i c a t io n o f t h e l ev e l o f u l t i m a t e

b i o d e g r a d a t i o n , t h e p o l y g l y c o l i n t e r m e d i a t e s i n t h e p l a n t

e f f l u e n ts w e r e d e t e r m i n e d b y t h e H B r f is s io n m e t h o d d e s-

c r i b e d b y T o b i n e t a l. ( 3) . T h i s t e c h n i q u e d e t e r m i n e s t h e

t o t a l - O C H 2 " C H 2 - f u n c t i o n a l g r o u p s p r e s e n t i n t h e s a m p l e .T h e r e s u lt s o b t a i n e d a r e g i v e n in T a b l e V I .

T h e r e s u l t s c l e a r ly d e m o n s t r a t e t h a t a l a r ge p r o p o r t i o n

o f t h e P E G - li k e i n t e r m e d i a t e s a r e r e m o v e d d u r i n g t r e a t m e n t

a n d s h o w t h a t a l c o h o l e t h o x y l a t e s u n d e r g o e x t e n s i v e ul ti -m a t e b i o d e g r a d a t i o n d u r i n g s e w a g e t r e a t m e n t .

I n c o n t r a s t , T o b i n e t a l. ( 3) f o u n d o n l y c a . 25 % ' P E G '

d e g r a d a t i o n w h e n t e s t in g D o b a n o l 9 E 0 in t h e O E C D c o n -

f i r m a t o r y t e st . T h e r a t h e r l o w a c t i v i t y o f s l u d g es g r o w n

o n s y n t h e t i c w a s t e s c o m p a r e d w i t h t h e h i g h l y a c t i v e b i o -

m a s s p r o d u c e d f r o m d o m e s t i c s e w a g e is t h e m o s t p r o b a b l e

e x p l a n a t i o n f o r t h e d i s c r e p a n c y .

A C K N O W L E D G M E N T S

Th e an a ly s i s fo r n o n io n ic s in p lan t s amp le s was d o n e b y J . Wa te r san d J .T . Ga r r ig an. T .R . Wi l l i ams p ro v id ed tech n ica l a s s i s tan ce .

R E F E R E N C E S

1. Wickb old , R. , Tens ide Deterg . 9 :173 (19 72).2 . B i rch , R .R . , Pre sen ta t io n a t th e XI I I Jo rn ad as d e l Co m i te

Esp an o l d e l a De te rg en c ia .3 . To b in , R .S .F . I . On u sk a , B .G . Bro wn lee , D . I [ . I. An th o n y an d

M.E. Co mb a , Wa te r Res . t0 :5 2 9 (1 9 7 6 ) .4 . R ich , L .G . , En v i ro n men ta l Sy s tems E n g in ee rin g , McG raw Hi ll

In c . , New Yo rk .

Manufacture of Fat ty Alcohols

Based on Natural Fa ts and Oi ls

UDO R . KREU TZ ER , Henke l KGaA , Pos tfach 1100, D -4000 Dusse ldor f 1 , West Germany

A B S T R A C T

Th e p re sen t wo r ld wid e cap ac i ty o f f a t ty a lco h o ls i s c a . 1 .0 mi l l io nme t r ic to n s p e r y ea r . Ab o u t 6 0 % o f th i s c ap ac i ty i s b a sed o n p e t ro -

ch emica l f eed s to ck s , 4 0 % o n n a tu ra l f a t s an d o i l s . Th ree b as ic d o -min a t in g co mmerc ia l - sca le p ro cesse s a re u sed to man u fac tu re f a t tya lco h o ls : th e Zieg le r p ro cess an d th e Ox o sy n th es i s s ta r t in g f ro mp e t ro ch emica l f eed s to ck s , an d th e h ig h -p re s su re h y d ro g en a t io n o fnatural fa t ty acids and esters . Basically , the h igh-pressure hydro-g en a t io n can b e u sed wi th t r ig ly ce r ide s , f a t ty ac id s o r f a t ty ac ides te r s as f eed s to ck . Th e d i rec t h y d ro g en a t io n o f f a t s an d o i l s ha s n o tb een d ev e lo p ed to a co mmerc ia l - sca le p rocess , ma in ly b ecau se i t wasn o t p o ss ib le to p rev en t d eco mp o s i t io n o f th e v a lu ab le b y p ro d u c tg ly ce ro l . Co n v e rs io n o f f a t ty ac id s in to f a t ty a lco h o ls b y ca ta ly t ich y d ro g en a t io n wi th o u t p ree s te r i f i c a t io n req u i re s co r ro s io n - re s i s tan tma te r ia l s o f co n s t ru c t io n an d ac id - re s i s tan t c a ta ly s t s . Req u i redreac t io n temp era tu re s a re h ig h e r , r e su l t in g in a h ig h e r h y d ro ca rb o nco n ten t . Th e ma jo r i ty o f f a t ty , a lco h o l p lan t s b a sed o n n a tu ra lfa t s an d o i l s u se me th y l e s te r s a s f eed s to ck . Th ese can b e mad ee i th e r b y e s te r i f i c a t io n o f f a t ty ac id s o r b y - t ran se s te r if i c a t io n o ft r ig ly ce r id e s . Fo r ca ta ly t i c h ig h -p re s su re h y d ro g en a t io n o f me th y l

e s te rs to f a t ty a lco h o ls , sev era l p ro cess o p t io n s h av e b een d ev e lo p ed .Th e b awic d i s t in g u ish in g fea tu re i s th e ca ta ly s t ap p l ica t io n e i th e rin a f ix ed b ed a r ran g eme n t o r su sp en d ed in th e me th y l e s te r f eed .

I N T R O D U C T I O N

F a t t y a l c o h o l s , p a r t i c u l a r ly t h e d e t e r g e n t r a n g e C 12 a n d

h i g h e r a l c o h o l s, h a v e b e c o m e a n i m p o r t a n t b a s ic m a t e r i a l

f o r a h o s t o f d e r i v a t iv e s a n d a p p l i c a t i o n s .T o d a y , i n th e W e s t e rn h e m i s p h e r e , t h e c o m m e r c i a l

p r o d u c t i o n o f f a t t y a l c o h o l s is b a s e d o n t h r e e d i f f e r e n t

p r o c e s s a l t e r n a t iv e s : t h e h i g h - p re s s u r e h y d r o g e n a t i o n o f

f a t t y a c i d s an d e s t e r s, t h e Z i e g l e r s y n t h e s i s, a n d t h e O x o

s y n t h e s i s .

T h e Z i e g l e r a n d O x o p r o c e s s e s s t a r t f r o m p e t r o c h e m -

i c a l f e e d s t o c k s p r o d u c i n g s y n t h e t i c a l c o h o l s, w h e r e a s

n a t u r a l f a t s a n d o i ls a re t h e r a w m a t e r i a l s f o r t h e h y d r o -

g e n a t i o n o f f a t t y a c i d s a n d e s t e rs t o n a t u r a l a l c o h o l s ( 1 ).

T h e p r e s e n t w o r l d c a p a c i t y o f n a t u r a l a n d s y n t h e t i c

f a t t y a l c o h o l s is c a . 1 . 0 m i l l i o n m e t r i c t o n s / y e a r ( T a b l e I ).

A r e g i on a l b r e a k d o w n o f t h e w o r l d c a p a c i t y i n t o n a t u r a l

a n d s y n t h e t i c f a t t y a l c o h o l s s h o w s t h a t i n t h e U S A th e

b u l k o f f a t t y a l c o h o l s i s o f p e t r o c h e m i c a l o r ig i n , w h e r e a s

i n E u r o p e m o r e t h a n 6 0 % o f t h e t o t a l v o l u m e i s m a d ef r o m n a t u r a l f a t s a n d o i ls . W o r l d w i d e , c a . 60 % o f t h e f a t t y

a l c o h o l c a p a c i t y i s b a s e d o n p e t r o c h e m i c a l f e e d s t o c k s a n d

JAOCS, vol . 61, no. 2 (February 1984)

8/8/2019 Proceso de Hidrogenacion New

http://slidepdf.com/reader/full/proceso-de-hidrogenacion-new 2/6

344

U . R. K R E U T Z E R

T A B L E I

W o rld C a p a c i t y 1 9 8 3 - N a t u ra l a n d S y n t h e t i c F a t t y A l c o h o l s

Natura l Synthe t ic

(1 ,000 met r ic tons )

E u r o p e 2 2 0 1 3 0

U S A 1 3 0 4 0 0A s i a 6 0 5 0

T o t a l 4 1 0 5 8 0

c a . 4 0 % o n n a t u r a l f a t s a n d o i l s .

T h e a c t u a l p r o d u c t i o n v o l u m e i s e s t i m a t e d t o b e o f t h e

o r d e r o f 7 0 0 , 0 0 0 m e t r i c t o n s / y e a r , c o r r e s p o n d i n g t o a n

o v e r a l l c a p a c i t y u t i l i z a t i o n o f c a . 7 0 % .

Process Alternative s

T h e c o m m e r c i a l p r o d u c t i o n o f n a t u r a l f a t t y a l co h o l s

s t a r t e d a b o u t 5 0 y e a r s a g o , b u t c o n t i n u o u s t e c h n o l o g i c a l

d e v e l o p m e n t i m p r o v e d t h e e c o n o m y o f t h is p r o c e s s s ig n i-

f i c a n t l y .

T r e m e n d o u s p r o g r e s s h a s b e e n m a d e , p a r t i c u l a r l y t oi n c r e a s e t h e a c t i v i t y , s e l e c t i v i t y a n d l i f e o f t h e c a t a l y s t

s y s t e m s , t o r e d u c e t h e e n e rg y c o n s u m p t i o n , a n d t o in s t a ll

a u t o m a t i c c o m p u t e r s y s t e m s to r u n a t o p t i m u m e f f ic i e n c y

w i th a m i n i m u m o f m a n p o w e r .

A l l c o m m e r c i a l p r o c e s s v a r i a t i o n s f o r t h e m a n u f a c t u r e o f

n a t u r a l f a t t y a l c o h o l s s t a r t w i t h f a t t y t r i g l y c e ri d e s a s r a w

m a t e r i a l . P r i m a r y f e e d s t o c k s f o r t h e C 1 2- C1 4 r a n g e a r e

c o c o n u t a n d p a l m k e r n e l o i l , a n d f o r C 1 6 -C 1 8 a l c o h o l s

t e c h n i c = l g r a d e s o f t a l l o w a n d p a l m o i l a r e u s e d .A g r e a t v a r i e t y o f s p e c i a l a l c o h o l s is r e a d i l y a v a i l a b l e

b y s e l e c t i o n o f a p p r o p r i a t e s t a r t i n g o il s , e . g ., b e h e n y l

a n d e r u c y l a l c o h o l f r o m r a p e s e e d o i l , h y d r o x y - s t e a r y l

a l c o h o l f r o m c a s t o r o i l , a n d a b r o a d r an g e o f u n s a t u r a t e d

a l c o h o l s w i t h i o d i n e v a l u e s u p t o 1 7 0 f r o m l i n s e e d o il .

F i g u r e 1 s h o w s t h e v a r i o u s r o u t e s f r o m n a t u r a l f a t s

a n d o i l s t o f a t t y a l c o h o l s .T h e o r e t i c a l l y , t h e s i m p l e s t w a y t o c o n v e r t f a t s a n d o i l s to

f a t t y a l c o h o l s is t h e d i r e c t h y d r o g e n a t i o n o f t r i g ly c e r i d e s.

T h i s o n e - s t e p p r o c e s s w o u l d s av e t h e m a n u f a c t u r e o f in t e r -

m e d i a t e s l i k e f a t t y a c i d s o r m e t h y l e s te r s. T h e c a t a l y t i c

h y d r o g e n o l y s i s o f t r i g l y c e r i d e s i s b a s i c a l l y f e a s i b l e , b u t

h a s a m a j o r d r a w b a c k . T h e r e a c t i o n c o n d i t i o n s w h i c h h a ve

t o b e e m p l o y e d w i t h t h e c a t a l y s t s s o fa r k n o w n a r e s o

s e v e re t h a t t h e v a l u a b l e b y p r o d u c t g l y c e r i n e u n d e r g o e s

f u r t h e r h y d r o g e n a t i o n t o a m i x t u r e o f p r o p y l e n e g l y c o l s

a n d p r o p y l a l c o h o l . S i n c e s a v i n g s i n c a p i t a l i n v e s t m e n t

c a n n o t m a k e u p f o r h ig h e r h y d r o g e n a n d c a t a l y s t c o n s u m p -

t i o n a n d t h e l os s o f t h e v a l u a b l e b y p r o d u c t g l y c e r i n e , th i s

r o u t e i s n o t p r a c t i c e d o n a c o m m e r c i a l s c al e .

A n o t h e r o p t i o n i s th e s p l i t ti n g o f f a ts a n d o i ls i n t o f a t t y

a c i d s a n d g l y c e r i n e a n d s u b s e q u e n t h y d r o g e n a t i o n o f t h e

f a t t y a c i d s t o f a t t y a l c o h o ls . T h e d i r e c t h y d r o g e n a t i o n o f

f a t t y a c i d s i n t h e a b s e n c e o f a n a l c o h o l c o m p o n e n t f o r p r e -

e s t e r i f ic a t i o n is c o n n e c t e d w i t h s o m e s p e c if i c r e q u i r e m e n t s

d u e t o t h e a c i d i c m e d i u m . M o s t o f t h e e q u i p m e n t h a s t o b e

m a d e o f c o r r o s i o n - r e s i s t a n t m a t e r i a l ; t h e h i g h - p re s s u r e p a r t

h a s t o b e d e s i g n e d f o r a h ig h e r t e m p e r a t u r e a n d p r e s su r e

t h a n f o r t h e m e t h y l e s t e r ro u t e ; a n d t h e c a t a l y s t h a s t o b e

a c i d - r e s i s t a n t .

T h e h y d r o g e n a t i o n o f f a t t y a c i d s is b a s ic a l l y f e a s ib l e

w i t h a c o p p e r c h r o m i t e c a t a l y s t o f th e A d k i n s t y p e , b u t t h e

r e d u c t i o n o f th e c a r b o x y l g r o u p r e q u i r e s t e m p e r a t u r e s o f

c a . 3 0 0 C , i . e ., c a . 5 0 - 1 0 0 C h i g h e r t h a n n e c e s s a r y f o r t h e

h y d r o g e n a t i o n o f m e t h y l e s t e rs . T h e s e m o r e r i g o ro u sr e a c t i o n c o n d i t i o n s l e a d t o a c e rt a i n a m o u n t o f o v e r h y d r o -

g e n a t i o n o f t h e a l r e a d y f o r m e d f a t t y a l c o h o l , r e s u l t in g in

OIL R FAT

1 0 L Y C E R I N ~~ I I G " C E ~ N ~

C R U D R A T F ~A C , ~ S

; §ES]ERIFICATION FRACTIONATIONOISTILLAIN

lCRUDE E] HYL STERS

;

I RACTIONArION]DISTILLATION

I

§

I HYDROGENATION

FATTY LCOHOLS

J I RACIIONATIONDISTILLAIION

I YDROGENATION

F I G . 1 . Ma n u f a ct u r in g ro u t es o f f a t t y a lco h o l s f ro m n a t u ra l f a t sa n d o i l s .

a h i g h e r p e r c e n t a g e o f h y d r o c a r b o n s . T h i s i s p a r t i c u l a r l y

t h e c a s e w h e n a b r o a d c u t o f f a t t y a c i d s is u s e d a s f e e d -

s t o c k .T h e f o r m a t i o n o f h y d r o c a r b o n s m e a n s a d r o p i n o v e r al l

y i e l d , s i n c e th e y c a n n o t b e r e c y c l e d i n t o t h e p r o c e s s .

T h e h y d r o g e n a t i o n c a t a l y s t h a s t o b e a b s o l u t e l y a c id -

r e s i s t a n t s in c e o th e r w i s e s o a p f o r m a t i o n w o u l d t a k e p l a c e ,

e n t a i l i n g a h i g h e r c a t a l y s t c o n s u m p t i o n a n d a d d i t i o n a lp u r i f i c a t i o n a n d r e w o r k s t e p s . T h e a c i d - r e s i s t a n t c o p p e r

c h r o m i t e t y p e i s r a t h e r e x p e n s i v e a n d s u s c e p t i b l e to p o i s o n -

i n g . T h u s i t h a s a s h o r t u s e f u l l i f e, a n d - a m a j o r d r a w b a c k

- a l l o w s o n l y c o m p a r a t i v e l y l o w t h r o u g h p u t r a t e s . T h i s

l o w s p a c e - t i m e y i e l d r e q u i r e s s i g n i f i c a n t l y l a r g e r r e a c t o r

v o l u m e s t h a n t h e m e t h y l e s t e r h y d r o g e n a t i o n .

L a s t n o t l e a st , t h e r e a r e so m e o p e n q u e s t i o n s r e g a r d in g

t h e l o n g - t e r m b e h a v i o r a n d c o r r o s i o n - r e s i s ta n c e o f s ta i n le s s

s t e e l t y p e s c o n t i n u o u s l y e x p o s e d t o f a t t y a c i d s a t a t e m -

p e r a t u r e o f c a . 3 0 0 C . T o m y k n o w l e d g e , i t i s b e c a u s e o f

t h e s e d i s a d v a n t a g e s t h a t t h e d i r e c t h y d r o g e n a t i o n o f f a t t y

a c i d s is n o t u s e d o n a l a r g e c o m m e r c i a l s c a l e .

L u r g i ( 2 ) h a s d e v e l o p e d a h y d r o g e n a t i o n p r o c e s s w h i c h

a l l o w s th e u s e o f f a t t y a c i d s a s f e e d s t o c k w i t h o u t p r e v i o u s

e s t e r i f i c a t i o n i n a s e p a r a t e u n i t . L u r g i c h a r a c t e r i z e s t h i s

s u s p e n s i o n p r o c e s s i n t h i s w a y : t h a t b y r e c i r c u l a t in g f a t t y

a l c o h o l i n a f i r s t s t e p , a n " i n s i t u " e s t e r i f i c a t i o n t a k e s

p l a c e t o c o n v e r t t h e f a t t y a c i d i n t o a w a x e s t e r . T h e s e c o n d

s t e p - t h e h y d r o g e n a t i o n o f t h is w a x e s t e r - o c c u r s s i m u l -

t a n e o u s l y i n th e s a m e r e a c t o r . T h i s m e a n s t h a t t h e p r o c e s sa c t u a l l y i s n o t a d i r e c t h y d r o g e n a t i o n o f a f a t t y a c id , b u t

t h e h y d r o g e n o l y s i s o f a n e s te r .

Methyl Ester Preparation

A s a r e s u lt o f t h e p r o b l e m s e n c o u n t e r e d i n th e d i r e c t

h y d r o g e n a t i o n o f f a t t y a c i d s , l o w - m o l e c u l a r - w e i g h t e s t er s

o f f a t t y a c id s , p r e f e r a b l y m e t h y l e s t e r s, h a v e b e c o m e t h e

p r i m a r y f e e d s t o c k . T o d a y t h e b u l k o f n a t u r a l f a t t y a l c o h o l s

i s m a n u f a c t u r e d v i a t h e m e t h y l e s t e r r o u t e . M e t h y l e s t er s o ff a t t y a c i d s ca n b e m a d e e i t h e r b y e s t e r if i c a t i o n o f f a t t y

a c i d s o r t r a n s e s t e r i f i c a t i o n o f f a t t r i g l y c e r i d e s .

JAOCS, vo l . 61 , no . 2 (F ebrua ry 1984)

8/8/2019 Proceso de Hidrogenacion New

http://slidepdf.com/reader/full/proceso-de-hidrogenacion-new 3/6

345

MANUFACTURE OF FATTY ALCOHOLS

The esterification can be done batchwise under pressure

at temper ature s of ca. 200-250 C. Since the esterifica tion is

an equilibrium reaction, the reaction water has to be

removed co ntinuo usly to obtai n a high ester yield.

A favorable process op tion is the con tin uou s esterifica-

tion in a countercurrent reaction column. Henkel has

developed a process technol ogy based on the principle of

an esterification reaction with a simultaneous absorption ofsuperheated methano l vapor and desorption of the reaction

water (Fig. 2) (3). The principle of this process is an esteri-

fication reaction with a simultaneous absorption of super-

heated methanol vapor and desorption of the reaction

wa te r .

Preheated fatt y acid cont aini ng an alkaline catalyst is

fed into a double bubble plate distillation column from the

top, countercurrent to methanol that enters the column

from the bottom. The reaction is carried out at a pressure of

ca. 10 bar and a temperature of 240 C. Excess methanol

can be ke pt significantly lower th an in the batch esteri-

fication. The batch process under pressure requires a

molar ratio of methanol to fatty acid of 3-4:1, whereas

for the con tin uou s process a molar ratio of 1.5:1 is suf-

ficient. The excess methanol leaves the column at the toptogether with water formed during the reaction (methanol /

water = 50:50 weight %), the methyl ester is taken off at

the bot tom and, afte r passing a flash vessel to remove

traces of methanol , enters a distillation unit. The methy l

ester leaving the flash vessel has an acid value of down to

0.5 and does no t require a refining step. The methy l ester

is separated from the catalyst cont aining residue by topping

off u nder vacuum. The metha nol is purified by rectification

and is reused as starting material.

The esterification is a preferential method for esters

from specific fatty acids, which no lo nger repre sent the

original composition of a natural fat, e.g., by separation

into an olein and a stearin fraction. The con tinuou s esteri-

fication process in a reaction column is superior to the

batch process, in that the same high yield can be obtained

in a muc h shorter dwell time and with a substanti ally lower

excess of methanol.

The predominant process for the manufacture of methyl

esters is the transesterification of fats and oils with meth-

anol. The ester intercha nge, i.e., the repl aceme nt of the

alcohol component glycerine by methanol takes place

METHANOL

AQUEOUSMETHANOL

4

I CATA L TETNANO:

VACUUM

METHYL ESTER

, ~

/ ~ FATTYACID

REACTION- FL A SH DISTILLATIONCOLUMN

FIG. 2. Manufacture of fatty acid meth yl esters by esterif ication.

RESIDUE

METHANOL01L CATALYST GLYCERNE

MEHYLESTERi

RESIDUE

, >

TRANSESTERIFICATION METHANOL/GLYCERINESEPARATION

METHYL ESTER

DISTILLATION

FIG. 3. Manufacture of fatty acid methyl esters by transesterification.

JA OCS , vo l . 6 1 , n o . 2 (F e b r u a ry 1 9 8 4 )

8/8/2019 Proceso de Hidrogenacion New

http://slidepdf.com/reader/full/proceso-de-hidrogenacion-new 4/6

3 4 6

U . R . K R E U T Z E R

q u i t e e a s i l y a t l o w t e m p e r a t u r e s o f c a . 5 0 - 7 0 C a n d u n d e r

a t m o s p h e r i c p r e s s u r e w i t h a n e x c e s s o f m e t h a n o l a n d i n

t h e p r e s e n c e o f a l k a l in e c a t a ly s t . A f t e r t h e r e a c t i o n m i x t u r e

h a s b e e n a l l o w e d t o s e t t l e , t h e l o w e r g l y c e r i n e l a y e r is

s e p a r a t e d a n d t h e r e m a i n i n g m e t h y l e s t e r c a n b e f u r t h e r

p r o c e s s e d .T h e s e m i l d r e a c t i o n c o n d i t i o n s , h o w e v e r , r e q u i r e a pr e -

n e u t r a l i z a t i o n o f t h e f a t b y m e a n s o f e .g . , a l k a l i r e f i n i n g ,

s t e a m d i s t i l la t i o n o f p r e e s t e r i f i c a t i o n o f f r e e f a t t y a c id s .

T h e r e m o v a l o f fr e e f a t t y a c i d s ( F F A ) i s n o t r e q u i r e d i f

t h e t r a n s e s t e r i f i c a t i o n i s c a r r ie d o u t u n d e r p r e s s u r e , e .g . ,a t 9 0 b a r a n d a t a h i g h e r t e m p e r a t u r e , e . g . , a t 2 4 0 C . U n d e r

t h e s e c o n d i t i o n s , e v e n i n f e r i o r g r a d e s o f f a t s a n d o i l s w i t h

a h ig h F F A c o n t e n t c a n b e c o n v e r t e d i n t o m e t h y l e s t e r s

w i t h o u t p r e n e u t r a l i z a t i o n , s i n c e a s i m u l t a n e o u s e s t e r i f i c a -

t i o n t a k e s p l a c e .

F i g u r e 3 s h o w s t h e p r o c e s s f l o w d i a g r a m o f a c o n t i n u o u s

t r a n s e s t e r i fi c a t i o n u n i t d e s i g n ed f o r h i g h e r p r e ss u r e a n d

t e m p e r a t u r e . U n r e f i n e d o i l, m e t h a n o l - i n an e x c e ss o f

s e v e r a l m o l e s - a n d a n a l k a l i n e c a t a l y s t a r e p r e h e a t e d t o

2 4 0 C a n d a r e f e d i n p a r a l le l f l o w i n t o t h e b o t t o m o f th e

r e a c t o r b y m e t e r i n g p u m p s . A f t e r fl a s h in g o f f th e b u l k o f

t h e e x c e s s m e t h a n o l , t h e r e a c t i o n m i x t u r e e n t e r s a se p a r a -t o r , i n w h i c h s e t t l in g in t o a n u p p e r l a y e r c o n t a i n i n g t h e

m e t h y l e s t e r a n d a l o w e r l a y e r c o n s is t i n g o f t h e g l y c e r i n e is

a l l o w e d . I n a b u b b l e t r a y c o l u m n w i t h r e f lu x , p u r e m e t h -

a n o l i s t o p p e d o f f a n d t h e n r e c y c l e d i n t o t h e t r a n s e st e r i -

f i c a t i o n st e p . T h e b o t t o m c o n t a i n i n g m e t h y l e s t e r a n d

g l y c e r i n e is c o m b i n e d w i t h t h e m a t e r i a l i n t h e s e p a r a t o r .

T h e g l y c e r i n e w i t h a p u r i t y o f m o r e t h a n 9 0 % is r e m o v e d

f r o m t h e e s t e r p r o c e s s , a n d t h e m e t h y l e s t e r is t r a n s f e r r e d

t o a s u b s e q u e n t v a c u u m d i s t i ll a t i o n . A c c o r d i n g t o f a t t y

a l c o h o l c h a i n d i s t r i b u t i o n r e q u i r e m e n t s , a s i m p l e o v e r h e a d

d i s t i l l a t i o n o r a r e c t i f i c a t i o n i n t o s p e c i a l c u t s m a y b e

a p p l i e d .

T h e t r a n s e s t e r i fi c a t i o n r e a c t i o n u n d e r a t m o s p h e r i c

p r e s s u r e d o e s n o t r e q u i r e p r e s s u r e v e ss e l s, r e s u l t in g i n lo w e r

c a p i t a l i n v e s tm e n t , a n d t h e e x c e s s o f m e t h a n o l c a n b ek e p t l o w e r t h a n i n t h e p r e s s u r e p r o ce s s .

T h e a m o u n t o f a q ue o u s m e t h a n o l t o b e r e w o r k e d f o r

r e c y c l i n g h as a s ig n i f i c a n t i m p a c t o n t h e e c o n o m i c s b e c a u s e

o f e n e r g y c o s t s . O n t h e o t h e r h a n d , a r e m o v a l o f f r e e f a t t y

a c i d s is m a n d a t o r y f o r t he p r o c e s s u n d e r a t m o s p h e r i c

p r e s s u r e , w h e r e a s t h e t r a n s e s t e r i f i c a t i o n u n d e r p r e s s u r e

a l l o w s t h e u s e o f i n f e r i o r g r a d e s o f o i l w i t h a h i g h F F Ac o n t e n t w i t h o u t p r e v io u s t r ea t m e n t .

High-Pressure Hyd rogen ation

F a t t y a c i d s o r t h e i r e s t e r s a re c o n v e r t e d i n t o f a t t y a l c o h o l s

b y h i g h - p r e s s u re h y d r o g e n a t i o n i n t h e p r e se n c e o f h e t e r o -

g e n e o u s c a t a l y s ts . T h e r e a r e s e v e ra l a p p r o a c h e s t o c l a s s i f y

t h e v a r i o u s p r o c e s s a l te r n a t i v e s, d e p e n d i n g o n w h i c h

f e a t u r e o n e w a n t s t o e m p h a s i z e . D e p e n d i n g o n t h e f o r m

a n d a p p l i c a t io n o f t h e c a t a ly s t , t h e h y d r o g e n a t i o n m e t h o d s

c a n b e d i v i d e d i n t o s u s p e n s i o n a n d f i x e d b e d p r o c e s s e s .

F i g u r e 4 s h o w s a s i m p l i f i e d p r o c e s s f l o w d i a g r a m o f a

s u s p e n s i o n h y d r o g e n a t i o n . F a t t y a c i d m e t h y l e s t e r a n d

h y d r o g e n a r e p r e h e a t e d s e p a r a t e l y a n d f e d i n t o t h e r e a c t o r

f r o m t h e b o t t o m . T h e c a t a l y s t , at l e a s t 2 % c o p p e r c h r o -

m i t e p o w d e r s u s p e n d e d i n m e t h y l e s t er , is a d d e d b y a

m e t e r i n g p u m p . T h e v e r t ic a l re a c t o r i s t u b u l a r a n d c o n -

t a i n s n o p a c k i n g . T h e h y d r o g e n a t i o n is a c c o m p l i s h e d a t c a .

2 5 0 - 3 0 0 b a r a n d 2 5 0 - 3 0 0 C . T h e e s te r t h r o u g h p u t p e r h o u r

i s i n t h e o r d e r o f m a g n i t u d e o f t h e r e a c t o r v o l u m e . C a . 2 0

m o l e s o f h y d r o g e n p e r m o l e o f e s t e r ar e f e d in t o t h e r e a c t o r

s e r vi n g n o t o n l y a s r e d u c i n g a g e n t b u t a l s o a s m e a n s o f

a g i t a t io n . T h e i n l e t t e m p e r a t u r e d e p e n d s u p o n t h e d e g re e

o f u n s a t u r a t i o n o f t h e f a t t y c a r b o n c h a in . S in c e t h e h y d r o -

g e n a t i o n b o t h o f t h e c a r b o n y l g r o u p a n d t h e c a r b o n d o u b l eb o n d s i s e x o t h e r m i c , t h e r e a c t i o n o f h i g h e r u n s a t u r a t e d

e s t e r s i s s t a r t e d a t t h e l o w e r e n d o f t h e a b o v e m e n t i o n e d

t e m p e r a t u r e r a n g e, f o r , w i th i n c r e a s i n g t e m p e r a t u r e , u n -

d e s i r e d s i d e r e a c t i o n s l ik e f o r m a t i o n o f h y d r o c a r b o n s a r e

f a v o r e d .

T h e r e a c t i o n m i x t u r e i s c o o l e d a n d s e p a r a t e d in t o l iq u i d

a n d g a s e o u s p h a s e s. T h e g a s , m a i n l y h y d r o g e n , i s r e c y c l e d

a n d t h e f a t t y a l c o h o l / m e t h a n o l m i x t u r e i s e x p a n d e d i n t o

a m e t h a n o l s t r i p p i n g u n it . A f t e r r e m o v a l o f t h e m e t h a n o l

t h e c a t a l y s t is f i l t e r e d o f f . T h e c r u d e f a t t y a l c o h o l s t i ll

c o n t a i n s 2 - 5 % e s t e r w h i c h c a n b e r e m o v e d b y a d d i t i o n o f

a l k a li t o f o r m s o a p w h i c h r e m a i n s i n t h e b o t t o m o f t h e

s u b s e q u e n t d i s t i ll a t i o n . D u e t o o v e r h y d r o g e n a t i o n o f t h e

f a t t y a l c o h o l , u p t o 2 - 3% h y d r o c a r b o n s a r e f o r m e d , l o w e r -

i n g t h e o v e r a l l y i e l d s i g n i f i c a n t l y . E v e n w i t h r e c y c l i n g , t h ec a t a l y s t c o n s u m p t i o n i s i n t h e r a n g e o f 0 . 5 -0 . 7 % .

S i n c e w i t h t h e u s e o f c o p p e r c h r o m i t e a s c a t a l y s t ,

c a r b o n d o u b l e b o n d s a l so a r e h y d r o g e n a t e d , o n l y s a t u r a t e d

f a t t y a l c o h o l s c a n b e o b t a i n e d , n o m a t t e r w h i c h m e t h y l

e s t e r i s u s e d a s f e e d s t o c k .

B a s i c a l l y , t h e s u s p e n s i o n p r o c e s s i s a l s o a p p l i c a b l e t o

t h e h y d r o g e n a t i o n o f f a t t y a c id s t o f a t t y a l c o h o ls , p r o v i d e d

t h a t t h e e q u i p m e n t i n t o u c h w i t h t h e f a t t y a c i d is m a d e

CATALYST~ = ~

FATTYCI DMETHYL STER

FATTYACDMETHYLESTER

i ACTORSEPARATORS

RECYCLEAS

HYDROGEN~ ,

I MET~

METHANOLSEPARATON

R I L T R A T 0 ~ ~

CRUDERATTY LCOHOLS

F I G . 4 . H igh -p ressu re h yd rogen at ion o f f a t t y a c i d m e t h y l e s t e rs - - suspension process.

JAOCS, vo l . 61 , no . 2 (February 1984)

8/8/2019 Proceso de Hidrogenacion New

http://slidepdf.com/reader/full/proceso-de-hidrogenacion-new 5/6

347

M A N U F A C T U RE O F F A T T Y A L C O H O L S

o f s t a i n l e s s s t e e l , a n d t h e c a t a l y s t u s e d i s a c i d - r e s i s t a n t ,

s u c h a s t h e A d k i n s - t y p e c o p p e r c h r o m i t e .

S i g n i f i c a n t ly d i f f e r e n t f r o m t h e s u s p e n s i o n t e c h n o l o g y

a r e p r o c e s s m o d i f i c a t i o n s b a s e d o n a f i x e d b e d c a t a l y s t

s y s t e m . D e p e n d i n g o n w h e t h e r t h e o r g a n i c fe e d p a s s e s

t h r o u g h t h e c a t a l y s t b e d m a i n l y v a p o r i z e d o r i n a li q u i d

s t a t e , t h e t e r m s v a p o r p h a s e o r t r ic k l e h y d r o g e n a t i o n a r e

i n u s e .S i n c e t h e s t a t e o f a g g r e g a ti o n o f t h e r e a c t i o n m i x t u r e

d e p e n d s o n a v a r i e t y o f p a r a m e t e r s s u c h a s t h e c a r b o n

c h a i n l e n g t h d i s t r i b u t i o n o f t h e o r g a n i c f e e d , t h e a m o u n t

o f r e c y c l e g a s, t e m p e r a t u r e a n d p r e s su r e c o n d i t i o n s , a n d

t h e o p t i o n a l a d d i t i o n o f s u b st a n c e s t o a i d i n v a p o r i z a t i o n ,

t h i s d i f f e r e n t i a t i o n i s n o t v e r y c l e a r l y d e f in e d . P r e f e r a b l y ,

o n e d i s t i n g u i s h e s b e tw e e n t h e f i x e d b e d p r o c e s s es b y t h e

k i n d o f c a t a l y s t u s e d , e i t h e r c o m p a c t p e l l e t i z e d o r s u p -

p o r t e d c a t a l y s t s o n a c a r r i e r. I n t h e p r o c e s s i n w h i c h a

m a s s i v e c a t a l y s t is e m p l o y e d ( F i g . 5 ) , a p a r t o f t h e o r g a n i c

f e e d i s v a p o r i z e d i n a n e x c e s s o f 2 0 - 5 0 m o l e s o f h y d r o g e n ,

a n d p a s s e d o v e r t h e f i x e d b e d c a t a l y s t . T h e h y d r o g e n a t i o n

i s a c c o m p l i s h e d a t a p r e s s u re o f 2 0 0 - 3 0 0 b a r a n d a t e m -

p e r a t u r e o f 2 0 0 - 2 5 0 C . T h e m e t h y l e s t e r i s m i x e d w i t h

f r e sh a n d r e c y c l e d h i g h - p re s s u r e h y d r o g e n a n d h e a t e d u p b yh e a t i n t e rc h a n g e w i t h t h e r e a c t i o n m i x t u r e l e a vi n g t h e

r e a c t o r . T h e f e e d is b r o u g h t u p t o p r o c e s s t e m p e r a t u r e b y a

p e a k h e a t e r a n d e n t e r s o n e o r s e v er a l r e a c t o r s f r o m t h e t o p .

T h e m a i n l y v a p o r i z e d m a t e r i a l p a ss e s o v e r th e f i x e d c a t a l y s t

b e d .

I n t h e c a se o f m a n u f a c t u r i n g s a t u r a t e d f a t t y a l c o h o l s ,

t h e c o m p a c t p e l l e t i z e d c a t a l y s t c o n s is t s o f a b l e n d o f m e t a l

o x i d e s c o n t a i n i n g c o p p e r , e . g ., c o p p e r / z i n c o x i d e . S i nc e t h e

r e d u c e d f o r m o f t h is c a t a l y s t i s p y r o p h o r i c , t h e a c t i v a t i o n

b y r e d u c t i o n i s u s u a l l y p e r f o r m e d i n t h e r e a c t o r. T h e

c o p p e r / z i n c c a t a l y s t i s n o t a c i d - r e s is t a n t a n d c o n s e q u e n t l y

n o t s u i t a b l e f o r t h e h y d r o g e n a t i o n o f f a t t y a c i d s.

I f a s p e c ia l c a t a l y s t c o n t a i n i n g z i n c i s u s e d a t s o m e w h a th i g h e r t e m p e r a t u r e s , t h e c a r b o n d o u b l e b o n d s o f u n s a t u r a t e d

f a t t y a c i d m e t h y l e s t e r s r e m a i n u n c h a n g e d , i . e ., u n s a t u r a t e de s t e rs c a n b e c o n v e r t e d i n t o u n s a t u r a t e d f a t t y a l c o h o l s .

T h e r e e x i s t c a t a l y s t s o f s u c h h i g h s e l e c t i v i t y t h a t , d e p e n -d i n g o n t h e d e g r e e o f u n s a t u r a t i o n o f t h e e s te r , e v e n h i g h l y

u n s a t u r a t e d f a t t y a l c o h o l s w i t h i o d i n e v a l u e s u p t o 1 7 0

c a n b e m a n u f a c t u r e d .

A f t e r l e a v in g t h e r e a c t o r , t h e r e a c t i o n m i x t u r e i s c o o l e d

a n d i s s e p a r a t e d i n t o l i q u i d a n d g a s e o u s p h a s e s i n a s e p a r a -

t o r . T h e g a s e o u s p h a s e c o n s i s t i n g m a i n l y o f e x ce s s h y d r o -

g e n i s r e c y c l e d a n d t h e l i q u i d p r o d u c t s t r e a m i s e x p a n d e d

i n t o a f la s h t a n k i n w h i c h m e t h a n o l i s s t r i p p e d f r o m t h e

f a t t y a l c o h o l . T h e f a t t y a l c o h o l s d o n o t r e q u i r e f u r t h e r

p u r i f i c a t i o n . I f , h o w e v e r , n a r r o w c u t s a r e d e s ir e d , a n d a

f r a c t i o n a t io n h a s n o t a l r ea d y b e e n m a d e w i t h t h e m e t h y l

e s t e rs , t h e f a t t y a l c o h o l s m a y b e f r a c t i o n a t e d i n a n a p p r o -

p r i a t e r e c t i f i c a t i o n u n i t .

T h e v a p o r p h a s e p r o c e s s c o n d i t i o n s a r e c o m p a r a t i v e l y

m i l d . T h e h i g h a m o u n t o f r e c i r c u l a t e d ga s p r o v i d e s f a s t

r e m o v a l o f t h e h e a t o f r e a c t io n , k e e p i n g s i de r e a c t i o n s

s u c h a s h y d r o c a r b o n f o r m a t i o n a t a v e r y lo w l ev e l . T h eo v e r a l l y i e l d o f f a t t y a l c o h o l is c a . 9 9% , w i t h a c o n t e n t o f

h y d r o c a r b o n s a n d n o n h y d r o g e n a t e d e s te r n o t e x c ee d i n g

1 .0 % . T h e c a t a l y s t c o n s u m p t i o n i s b e l o w 0 . 3 % .

T h e f i x e d b e d p r o c e s s in w h i c h a s u p p o r t e d c a t a l y s t is

e m p l o y e d i s b a s i c a ll y c a r r i ed o u t i n a b o u t t h e s a m e u n i t

a s u s e d f o r m a s s i v e c a ta l y s t s . A l s o , t h e r e a c t i o n c o n d i t i o n s

a r e si m i l a r t o t h o s e f o r c o m p a c t c a t a l y s t s.

T h e m o s t d i s t i n g u i s h i n g f e a t u r e i s t h a t t h e o r g a n i c f e e d

t r i c k l e s d o w n o v e r t h e f i x e d c a t a l y s t b e d i n a l i q u i d s ta t e .

T h e m o l a r e x ce s s o f h y d r o g e n a n d t h e r e w i th t h e a m o u n t

o f r e c y c l e d g a s i s c o n s i d e r a b l y l o w e r t h a n i n t h e p r o c e s s

w i t h c o m p a c t c a t a l y st s . B e c a u s e o f t h e l iq u i d s t a te o f th e

f e e d , t h e c a t a l y s t h as t o b e o f a h ig h m e c h a n i c a l s t a b i l i t y ;

t h e r e f o r e , s u p p o r t e d c a t a l y s t s l i k e 2 0 - 4 0% c o p p e r c h r o m i t e

o n a s i l i c a g e l c a r r i e r a r e u s e d . T h i s h i g h m e c h a n i c a l s t a b i -l i t y o f t h e s u p p o r t e d c a t a l y s t a ll o w s a l so th e h y d r o g e n a t i o n

o f m a t e r i a l s n o t e a s i l y v o l a t i l i z e d , l i k e w a x e s t e r s .

T h e f a t t y a l c o h o l s f r o m t h i s p ro c e s s a r e o f th e s a m e

h i g h q u a l i t y a s a c h i e v e d w i t h m a s s i v e c a t a l y s t s , p a r t i c u l a r l y

w i t h r e g a r d t o t h e l o w h y d r o c a r b o n c o n t e n t . T h e s p e c i fi c

c a t a l y s t c o n s u m p t i o n c a n b e k e p t d o w n t o ca . 0. 3 % .

S i n c e t h e s p e c i f i c t h r o u g h p u t r a t e , i . e ., t h e s p a c e -

t i m e y i e l d , i s h i g h e r w i t h m a s s i v e c a t a l y s t s , p l a n t s u s i n g

c a r r i e r c a t a l y s t s r e q u i r e l a r g e r h i g h p r e s s u r e r e a c t o r s f o r t h e

s a m e t h r o u g h p u t . O n t h e o t h e r h a n d , t h e a m o u n t o f

r e c y c l e g a s c a n b e k e p t l o w e r , w h i c h a l l o w s r e d u c t i o n si n o t h e r e q u i p m e n t , s u c h a s g a s r e c i r c u l a t i o n p u m p s , a n dp i p i n g d i m e n s i o n s .

S o m e p r o s a n d c o n s o f t h e s u s p e n s i o n v e r s u s t h e f i x e d

b e d h y d r o g e n a t i o n p r o c e s s a r e a s f o l l o w s . T h e c a p i t a l

i n v e s t m e n t r e q u i r e d f o r t h e s u s p e n s i o n p r o c e s s i s e s t i m a t e d

t o b e s o m e w h a t l o w e r t h a n t h a t f o r t h e f i x e d b e d p r o c e s s.

C o s t s o f a d d i t i o n a l e q u i p m e n t f o r t h e s e p a r a t i o n o f t h e

s u s p e n d e d c a t a l y s t , t h e d i s t i l l a ti o n o f t h e c r u d e f a t t y

a l c o h o l , a n d r e w o r k o f t h e u n r e a c t e d m e t h y l e s t e r is m o r e

t h a n c o m p e n s a t e d b y l a r g er r e a c t i o n v e s se ls , g a s r e c i rc u l a -

t i o n p u m p s , a n d p i p e w o r k i n t h e h i g h p r e s s u r e p a r t o f t h e

f i x e d b e d p l a n t .

A s f a r a s t h e c o n s u m p t i o n o f r a w m a t e r i a l i s c o n c e r n e d ,

t h e f i x e d b e d p r o c e s s h a s a n a d v a n t a g e b e c a u s e th e c o n v e r-

s i o n o f t h e e s t e r i n t o f a t t y a l c o h o l i s a l m o s t q u a n t i t a t i v e

FATTY ACiD

METHYL ESTER

HYDROGEN, > - -

P R E H E ~ Ir c o J

I

RECYCLINGAS

GASOMETER

F L A S H A N K

F AT T Y LC OH OL

FIG. 5 . High-pressurehydrogenationof fa t ty ac id methy l es te r s - f ixed bed process .

JAOCS, vo l . 61 , no . 2 (February 1984)

8/8/2019 Proceso de Hidrogenacion New

http://slidepdf.com/reader/full/proceso-de-hidrogenacion-new 6/6

348

U.R. KREUTZER

with a very low formation of hydrocarbons. The catalyst

consumption of the suspension process, which is in the

range of 0.4-0.7%, is considerably higher than in the fixed

bed process (0.2-0.3%). Energy consu mpt ion is estima ted

to be in the same order of magnitude, the suspension pro-

cess requiring higher temperatures, and the fixed bed process

having a larger power insta1Ied for bigger recircuIation

pumps and compressors.The qualit y of the crude fatty alcohols resulting from

the fixed bed process is better, with a lower hydrocarbon

cont ent and lower saponification values. The fatty alcohol

of the suspension process can be brought up to the same

quality level; however, this requires an additional purifica-tion step.

REFERENCES

1. Schdtt, H., UIImanns Encyklopi~die der Techn. Chemic, 4th

edn., Vol. 11, 1976, p. 427.2. Buchold, H., Chem. Eng. 90:42 (1983).3. Jeromin, L ., et al., Fette, Seifen, Anstrichm. 83:493 (1981).

W est European Household D etergent Trends

E. SO LL EV EL D, S hel l International Chem ical Co. Ltd., Shel l Centre, London SE1 7PG,United Kingdom

A B S T R A C T

It is estimated that there wil l continue to be a relatively stronggrowth in demand for alcohol derivatives, ca. 3 times as high asthat for the product sector as a whole. Detergent alkylate growthwill be somewhat lower, but it will remain the staple diet of theindustry and by far the single largest volume detergent intermediate.

Household detergents - both the heavy-duty product s

used for the domestic laundry and the light-duty washing-

up liquids - const itut e the single largest segment of various

detergent market sectors. In terms of active matter, it

represents some 60% of a total annua l West Europ ean

demand currently r unning at ca. 1,200,000 metric tons.

The household market is tending towards maturity and

its growth has now declined to levels below expectedaverage West European GNP growth rates. Although the

future detergent product growth rates may be modest in

comparison with those of the 1950s and 1960s, the growth

in demand for particular types of active matter is expected

to be considerably higher. Within an overall modest growth

rate for the product as sold to the consumer and assuming

no change in average active matter content, a high relative

growth rate for particular types of active matter can be

achieved if products are reformulated.

The driving forces for the expected reformulation -

particularl y of the heavy-du ty produc ts - are provided by

both environmen tal requirements and the need to mainta in

the pro ducts as new and innovative in the consu mer's

mind. Thus, even in depressed economic conditions, one

would expect change to occur, and, particularly if this iscoupled with improved cost performance of the product,

change becomes inevitable.

It is necessary for a company like my own, a major

supplier of detergent intermediates (the chemical deriva-

tives of which find their way into the products sold to the

consumer) to understand these formulatory trends if we

are going to con tin ue to be successful in providing produ cts

in the right volumes at the right times in response to mar ketrequirements.

L I G H T - D U T Y L I Q U I D S

Former growth rates of 7-8% per ann um have declined and

are expected to be of the order of 1-2% per annum until the

end of the decade. The historical usage and expected futuredemand is shown in Table I.

The higher growth rate in the latter part of the decade is

JAOC S, vol. 61, no. 2 (February 1984)

caused by some count ries changing from powd ers to liquids.Formulation of light-duty liquids has changed over the

last 10 years principally as a result of the introduction of

paraffin sulfonates. Further changes are expected as alpha

olefin sulfonate s (AOS) be come increasingly available and

afford the formulator the opportunity to improve the

mildness of the product while mainta ining detergency. The

expected changes in demand for active matter are shown in

Table 1.

H E A V Y - D U T Y S E C T O R

The heaw-duty product sector is by far the largest of the

household product market, as shown in Table lI. It is in

this sector that environmental constraints have, and will

continue for some time to have, a strong influence on theformu lati on of these products. Signific ant parameters inthis context are:

-t re nd towards lower phosphate levels from 30-40%

to ca. 20% backed by legislation in some countrie s;

-energy conservation lowering average wash tempera-

tures from 60 C to 40 C;

-further slight increase of the synthetic component in

the textile mix; and

- product cost/performance.

Although 2-3 years ago we expected the industry res-

ponse to these requirements to be both higher active matter

levels and increased usage of alcohol long-chain etho xylat es

(nonionics), matters developed differently. Currently there

are four separate trend s or comb inat ions of these: high

nonionic based formulations, high bleach levels, use ofbleach activators, and zeolite/phosphate combinations.

The basic expectation that usage of nonionics would

increase was correct. It is relevant to point out th at the

reason for the use of long-chain ethox ylates was their

lower sensitivity to hard water - compared to alkyl benz ene

sulfonat e - and their efficiency in cleaning, particularl y of

synthetic s. The use of these prod ucts also permit ted the

cost/performance of the product to the enhanced: washing

efficiency was improved and the expensive phosphate

compo nent reduced. Additionail y, heavy-duty Iiquids were

introduced into German y and France - two of the major

detergent markets in West Europe -- the majority of these

liquids contain no phosphate; to compensate for this, they

contain nearly 3 times as much active matter as powders

per unit weight of product.Although we expect that, for the reasons already cited,

long-chain ethoxylates will continue to increase it is also