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Kinetics of Hydroformylation of Ethylene in a Homogeneous

Medium: Comparison in Organic and Aqueous Systems

Raj Madhukar Deshpande, Bhalchandra Mahadeo Bhanage,Sunil Sadashiv Divekar, Subbareddiar Kanagasabapathy, andRaghunath Vitthal Chaudhari*

Chemi cal E ngi neeri ng Di vi si on, Nat i onal Chemi cal Laborat ory, P une 411 008, I ndi a 

The kinetics of hydroformylation of ethylene was studied using HRh(CO)(PPh 3)3 an d [Rh(COD)-C I ]2/TP P TS cat a lyst in t oluene and w a ter media, r espectively. The ra tes w ere found to have afirst-order dependence on th e cat a lyst concentra tion. Simila r trends w ere observed wit h respectto part ial pressures of ethy lene and ca rbon monoxide, in both solvents. The difference in t helocation of the ma xima wit h r espect to pressure is due to the poor solubility of th e reacta nts inwa ter a s compar ed to toluene. The ma jor difference observed w a s a 1.5 order w ith hy drogen intoluene compa red with a f irst order in wa ter. Ra te models were proposed to represent t he dat aobserved.

Introduction

H y dro formy la t ion of olef ins is a n import a n t a n d

largest scale applicat ion of homogeneous catalysis inindustry, used for the man ufacture of C3-C 40 aldehydesan d alcohols. Hy droformy lat ion of ethylene is one suchexample leading to propionaldehyde and   n -propanol asmajor products having applicat ions such as solvent ,intermediates in the manufacture of pharmaceuticals,pesticides, and perfumery products.

I t is a lso an importa nt st ep in the new non-HC N routefor methyl metha crylat e ma nufacture (Schwa ar, 1991).While extensive work has been done on catalysis andproduct distribut ion/selectivity in hydroformyla tion re-

a c t io n s , t h e re is l imit e d p u blis h e d l i t e ra t u re o n t h ekinetic modeling of hydroformyla t ion of ethylene. Inthis paper investigat ions on the kinetic modeling ofhydroformylat ion of ethylene using a HRh(CO)(P P h 3)3

cata lyst in a n organic medium a nd a wa ter-soluble Rh/TP P TS (TP P TS  ) (triphenylphosphine)tr isulfona te so-dium salt) catalyst in an aqueous medium are reported.The lat ter case is important from the point of view ofs ep a ra t io n o f p rodu ct s a n d ca t a ly s t , du e t o t h e lo we rsolubility of propiona ldehyde in aq ueous medium. Thereaction involves simultaneous absorption of three gaseswith the cata lytic reaction in t he liquid phase to producea single liquid product . A knowledge of the int rinsickinetics is essentia l to at tempt a systemat ic an alysis ofthe role of mass tra nsfer in such a system. Such a study

not only is useful for the improvement of t he cata lyt icsystem but also provides t he basic informa tion for t hedesign and scale-up of suitable reactors.

The kinetics of hydroformylat ion of olefins using ahomogeneous H Rh(CO)(P P h 3)3   comp le x ca t a ly st h a sbeen st udied by ma ny investigators (Deshpan de et a l . ,1988; D ivekar et al . , 1993). For hydr oformylat ion ofe t h y le n e, h owe v er , t h e a v a i la ble in f orma t io n in t h eliterat ure is scan ty. A few reports describe the kinetics

of this reaction using a supported Rh complex catalyst(Ara i et al . , 1975; Taka ha shi et al . , 1992). However,on the industrial scale a homogeneous Rh complex is

used, and h ence it is more importa nt to investigat e thekinetics using a soluble Rh complex catalyst. Polievkaet al. (1980) have studied the kinetics of hydroformy-lat ion of ethy lene using homogeneous Rh(CO)Cl(PP h3)2

but in a very nar row ra nge of conditions. They observedt h a t t h e ra t e v ers u s e t h y len e p re s su re c u rve p a s s e sthrough a ma ximum. The present w ork deals with thestudy of the kinetics of hydr oformy lat ion of ethylene inan organic medium using a HRh(CO)(PPh 3)3   c a t a ly s tand in a queous medium using a [Rh(COD)Cl]2/TP P TScatalyst and developing rate equations.

In this paper HRh(CO)(PPh 3)3  catalyzed hydroformy-lat ion of ethylene has been investigated in a tempera-t u r e r a n g e o f 333-373 K . Th e e ff ect s of ca t a l y st

concentra tion, part ial pressure of CO, H2, and ethyleneon the rat e of reaction have been studied using a stirr edpressure reactor. The kinetics of ethylene hydroformy-lat ion using a wa ter-soluble [Rh(COD)Cl]2/TP P TS cat a -lyst has also been investigated at 313 K, wherein theeffect of different process parameters on the activity ofthe cata lyst ha s been observed. The kinetics in thesesystems ha ve been compared.

Experimental Section

Th e re a c t ion s we re c a rr ie d o u t in a s t irred ba t c hreactor manufa ctured by Pa rr In strument C o. (Moline,I L ), h a v ing a ca p a c i t y o f 300 mL . Th e re a c t or wa sconnected to a pressure transducer-recorder system for

monitoring of the pressure drop in the reactor due tot h e r ea c t ion . Th e t e m p er a t u r e of t h e r ea c t or w a scontrolled by mea ns of a P ID controller and aut omaticcooling system. The ca ta lyst/ligan d wa s cha rged alongw i t h t h e s o l v e n t i n t o t h e r e a c t o r a n d h e a t e d t o t h edesired temperature. Et hylene wa s cha rged individu-a l ly in t o t h e re a c t or u p t o t h e de s ired p res s u re u n t i ls a t u ra t ion . Th is wa s f ol lowe d by CO a n d H 2  u n t i l t h er eq u ir ed p a r t ia l p re ss u re w a s a t t a i n ed . Th e w h ol eoperation wa s done at very low a gitat ion speed to ensuret h a t n o r ea c t ion t ook p la c e d u r i ng a d d i t ion of t h ereactant s. Following this, the agita t ion wa s increased

* To whom correspondence should be addressed. Fax:   +91212 333941. E -ma il: ihcu@ems.ncl.res.in.

C H 2dC H 2 + C O  + H 298 c a t a l y s t

C H 3-C H 2-C H O (1)

2391Ind. Eng. Chem. Res.  1998, 37 ,  2391-2396

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to 900 rpm a nd the recorder w as sw itched on. The dropin the pressure of the rea ctor w as measured for a f ixedt ime. Th e se da t a we re u s ed t o ca lc ula t e t h e ra t e s o f

reaction as follows:

wh e re V L  ) liquid volume in th e reactor (m3), V G  ) voidspace in the reactor (m 3),   Z   ) compressibility factor;   R 

) gas constant (MPa m 3 kmol-1 K-1);  T   ) temperatureof the gas in the reactor (K);   P  )   total pressure in thereactor at any t ime less vapor pressure (MPa), and   P 0)   init ial pressure in the reactor less vapor pressure(M P a ). Th e r a t e of r ea c t ion i s b a s e d on t h e 1: 1: 1stoichiometry a s shown in eq 1. A typical plot of thepressure drop with t ime is shown in Figure 1 for theeffect of  P C O on the ra te of reaction at 373 K in toluene.

The analysis of the product propionaldehyde was doneon GLC using a thermal conductivity detector (TCD).Only hydr oformylat ion products were observed in t hereaction crude. No hydrogena tion wa s observed. Hence,t h e ra t e s c a lc u la t e d by e q 2 we re t h e ra t e s o f h y dro -formylation only.

Using this m ethod t he effects of part ia l pressures ofethylene, CO, and H 2 an d cata lyst concentra t ion on therates of react ion in toluene and water were studied inthe range of conditions given in Table 1.

Results and Discussion

(a) Studies in a Toluene Medium Using a HRh-(CO)(PPh3)3 Catalyst.   The effect of agitation speed

wa s f irs t in v e s t ig a t e d a t t h e h ig h e s t t e mp e ra t u re o fs t u dy ( 373 K ) u n de r s t a n da rd con dit ion s , a n d i t wa s

o bs e rv e d t h a t t h e ra t e wa s in de p e n de n t o f a g i t a t io nbeyond 600 rpm. All reactions w ere hence conducteda t 900 rp m t o e n s ure t h a t t h e re a c t ion occu rs in t h ekinetic regime. The effect of cata lyst concentra tion onthe ra te of hydroformylat ion of ethylene wa s studied atethylene, CO, and H 2  partial pressures of 0.689, 1.378,and 1.378 MPa, respectively, in a temperature range of333-373 K. The results a re shown in Figure 2, whichindica te a first-order dependence on cat alyst concentra-t ion. This is expected a s enhan cement in t he cata lystconcentration increases the concentration of the activecatalyt ic species and hence the rate.

Effect of thePartial Pressure of Hydrogen.   Theeffect of the part ial pressure of hydrogen was studiedat ethylene and CO pa rtia l pressures of 0.689 an d 1.378

MPa , respectively, in a tempera ture ra nge of 333-373K a nd a t cat alyst concentra t ion of 1.0  × 10-3 km ol/m 3.The results a re shown in Figure 3. I t is observed tha tthe rate has a strong positive dependence on hydrogenpressure of the order of 1.5. Simila r tr ends were ear lierreported by Deshpande et al. (1988) for hydroformyla-tion of 1-hexene. At lower   P H 2   formation of dimericspecies is possible as shown by (Evans et al. , 1968)

The formation of such species will lead to a reductionin the concentration of active catalytic species which willbe more p ron ou n ce d a t lowe r h y drog e n p res s u res .

Table 1. Range of Conditions Investigated for the Kinetic Study

descr ipt ion t oluen e w a t er

concentrat ion of cata lyst , kmol m-3 (0.5-4.0) × 10-3 (0.2-1.0) × 10-3

pa r t ia l pr essur e of et h y len e, MP a 0.414-2.756 0.414-2.067pa r t ia l pr essur e of h y dr ogen , MP a 0.414-2.756 0.414-2.067pa r t ia l pr essur e of C O, MP a 0.414-2.756 0.414-2.067t em per a t ur e, K 333-373 313reaction volume, m 3 10 × 4 2.5 × 10-5

Figure 1.   Ty p ic a l a b s or p t ion d a t a f or r e a ct ion in a t olu e n emedium. React ion condit ions:   P H 2

, 1 . 3 7 8 , M P a ;   P ethylene, 0.689MPa ; concentrat ion of cat alyst , 1  × 10-3 kmol m-3; temperature,373 K.

Figure 2.   Effect of cata lyst concentrat ion on th e rat e of react ionin a toluene medium. React ion condit ions:   P ethylene, 0.689 MPa;P CO , 1.378 MPa ;   P H 2

, 1.378 MP a.

R  )[(1 - P /P 0)P 0]V G

3Z R T V  L(2)

2HRh(CO)(PPh3)3 T  [Rh(CO)(PPH 3)2]2 + H 2   (3)

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B e s id es t h is , a s s h ow n i n F i gu r e 4 , t h e ox id a t i veaddit ion of H 2   to acyl species is the rate-determiningstep in this r eact ion. A combined effect of these twosteps could give an order of reaction higher than unity.

Effect of the Partial Pressure of Ethylene.   Theeffect of the partial pressure of ethylene was studied atH 2   and CO part ial pressures of 1.378 MPa each, in at e mp e ra t u re ra n g e o f 333-3 7 3 K a n d a t a c a t a l y s tconcentration of 1.0   ×  10-3 km ol/m 3. Th e res u lt s a res h ow n i n F i g ur e 5 . I t i s ob se rv ed t h a t t h e r a t e i sinversely proportional to the ethylene concentration andshows a typical substra te inhibit ion. The forma tion ofalkyl olefinic complexes like C 2H 5Rh(CO)3C 2H 4   in h y -droformylation of ethylene with a Rh 4(CO)12 cata lyst hasbeen r eported by King et a l . (1980). In the present

work, formation of similar species is possible at highethylene concentra tions, resulting in a lowered concen-tra tion of active cata lytic species an d hence a reductionin the r at e of react ion, as seen in Figure 4.

Effect of the Partial Pressure of Carbon Mon-oxide.   The effect of the part ia l pressure of carbonm on ox id e w a s s t u di ed a t e t hy l en e a n d H 2   p a r t ia lpressures of 0.689 and 1.378 MPa, respectively, in at e mp e ra t u re ra n g e o f 333-3 7 3 K a n d a t a c a t a l y s tconcentra tion of 1.0 × 10-3 km ol/m 3. The results showni n F i g u r e 6 i nd ica t e a ca s e of a t y pi ca l s u bs t r a t e -in h ibi t ed k ine t ics wh ich is v ery we ll e s t a bl ish e d inhydroformyla t ion react ions. This t rend is observed

Figure 3.   E ffect of the part ia l pressure of hydrogen on the ra teof react ion in a toluene medium. React ion condit ions:   P ethylene,0.689, MPa;   P CO , 1.378,MPa ; concentrat ion of catalyst , 1  × 10-3,kmol m-3.

Figure 4.   Mechanism of hydroformylat ion using a HRh(CO)-( P P h 3)3  c a t a ly s t .

Figure 5.   Effect of the part ia l pressure of ethylene on th e rat e ofreact ion in a toluene medium. R eact ion condit ions:   P H 2

, 1.378

M P a ;   P CO , 1.378 MPa; concentrat ion of catalyst , 1   ×   10-3 kmolm-3.

Figure 6.   Ef f e c t of t h e p a r t ia l p r e s s u r e of CO on t h e r a t e ofreaction in a toluene medium. Reaction conditions:   P ethylene, 0.689M P a ;   P H 2

, 1.378 MPa; concentrat ion of catalyst , 1   ×   10-3 kmolm-3.

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s in ce , a t h ig h   P C O, in a c t iv e di- a n d t r ic a rbo n y la c y l-rhodium species are formed, leading to a sharp drop in

a c t ivi t y . At lo we r   P C O   a posit ive dependence is ob-s erv ed, p ert a in in g t o e n h a n ce d f orma t io n of a c t ivecatalytic species HRh(CO)2( P P h 3)2  (Figure 4).

(b) Reactions in an Aqueous Medium Using a[Rh(COD)Cl]2/TPPTS Catalyst System.  The kineticsof hydroformylat ion of ethylene w as also studied usinga [Rh(COD)Cl]2/TP PTS cata lyst system. The a ct ivecata lyst here is ana logous to tha t in a toluene medium.The main objective of this study was to investigate andcompare the hydroformyla t ion kinetics in toluene a ndin a reactive medium like w a ter. This is importa nt sincewa ter-soluble cata lyst is being commercially a pplied forhydroformyla t ion of propylene to   n -butyra ldehyde byHoechst (Corn ils a nd Wiebus, 1995, 1996). The effects

of catalyst concentrat ion and part ial pressures of eth-ylene, CO, and H 2  on the ra te of react ion w ere studiedat a temperature of 313 K and 1000 rpm (to ensure akinetic regime).

It may be noted that the catalyst concentrat ion usedi n t h i s c a s e i s h a l f t h a t u s e d i n t h e c a s e o f t o l u e n em a i n l y b e c a u s e t h e r e a c t i o n w a s f o u n d t o b e m a s stransfer controlled at a catalyst concentrat ion of 1   ×

10-3 km ol/m 3; a lso, the pressures of CO, ethylene, a ndhydr ogen used for this stu dy ar e 0.689 MP a ea ch. Thecata lyst w as prepar ed in situ using [RhCl(COD)]2  a n dTPPTS in the ratio of 1:6.

The main objective was also to establish the trendsin a n a q u e ou s me diu m a n d c omp a re wit h t h o se in a norg a n ic mediu m. H e n ce , t h e da t a we re obs erv ed a t asingle temperat ure of 313 K.

A first-order dependence is observed w ith respect tothe cata lyst concentra t ion as shown in Figure 7. Thistrend is similar to tha t observed in t he case of toluenea s t h e r e a c t ion m ed iu m . Th e e f fe ct of t h e p a r t i a lpressure of hydrogen also shows a f irst-order depen-dence (see Figure 8). This result is ma rkedly differentfrom the 1.5 order observed in toluene. Wa ter being apolar solvent, the format ion of dimeric species (eq 3) isnot facilita ted. B esides, the formation of such specieswill also depend on the concentrations of other reactantsl ik e C O a n d et h yl en e. I t i s w el l-k now n t h a t t h esolubilit ies of all three of these gases are much lowerin water as compared to toluene (see Table 2).

The ra te versus CO pa rt ia l pressure passes througha m a x im u m a s s h ow n i n F i gu r e 9. I n c on t r a s t , i n atoluene solvent , only a negative order dependence isobserved with   P C O, in the same pressure range (0.4-2.76 MPa ). Although, the ma xima with   P CO  have beenwell documented in hydroformylat ion chemistry, thedifference in the trends observed in water versus thosei n t ol ue ne i s d u e t o t h e p oor s ol ub il it y of ca r b onmonoxide in wa ter a s compared to tha t in toluene. Theconcentration of CO at low pressures is too low to givethe format ion of di-a nd tr icarbonylacylrhodium species(see Figure 4), giving a positive order dependence wit hrespect to CO in this ra nge. The inhibition observed at

Figure 7.   Ef f e c t of t h e c a t a ly s t c on c e n t r a t ion on t h e r a t e ofreact ion in an aqueous medium. React ion condit ions:   P ethylene,0.689 MPa;  P CO , 0.689 MPa;  P H 2

, 0.689 MPa; temperature, 313 K.

Figure 8.   E ffect of the part ia l pressure of hydrogen on the rat eof react ion in an aq ueous medium. Rea ct ion condit ions:   P ethylene,0.689 MPa ;   P CO , 0.689 MPa; concentrat ion of catalyst , 5   ×  1 0-4

kmol m-3; Rh /TP P TS, 1:6; tempera tur e, 313 K.

Table 2. Solubility of Ethylene, CO, and H2 in Tolueneand Water

solubility, MP a m 3 kmol-1

solv en t t em per a tu re, K et hy len e h yd rog en C O

w a t er 313 40.33 191.06 211.04t oluen e 333 1.904 61.69 18.51t oluen e 353 2.791 90.69 23.02t oluen e 373 9.209 153.02 29.62

Figure 9.   Ef f e c t of t h e p a r t ia l p r e s s u r e of CO on t h e r a t e ofreact ion in an aqueous medium. React ion condit ions:   P ethylene,0.689 MPa ;   P H 2

, 0.689 MPa; concentrat ion of catalyst , 5   ×   10-4

kmol m-3; Rh/TP P TS, 1:6; tempera tur e: 313 K.

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higher pressures is mainly due to the forma tion of theseina ctive species.

Figure 10 shows the effect of the par t ial pressure ofethylene on the ra te of react ion. The trend is similarto tha t observed w ith car bon m onoxide. A first-orderdependence is observed up to a n ethylene pressure ofalmost 1 MPa , whereas in the case of toluene even a t apressure of 0.4 MPa , a nega tive order is observed. Thei nh i bi t ion w i t h a n i n cr ea s e i n t h e e t hy le ne p a r t ia lpressure is mainly due to the formation of diolefinicspecies, as mentioned ea rlier. At lower ethylene pa rtia lpressure, in a n a queous medium, t he concentra t ion ofethylene is too low to generate inhibitory species an d,hence, a first -order dependence is observed. This canbe at t ributed to the increased format ion of act ive alkylrhodium species (Figure 4) and, hence, rate.

Kinetic Model.   I n o r d e r t o e n s u r e t h a t t h e d a t aob se rv ed a r e i n t h e k in et i c r e gi m e, t h e r a t e s w e r ec o mp a re d wit h t h e ma x imu m ra t e s o f ma s s t ra n s f e rpossible under react ion condit ions (k LaA * ). F o r t h is

purpose, the value of   k La  was obtained as discussed inthe literature, for stirred dead-end reactors of the sametype as used in this work (Chaudhari et al. , 1987). Thek La  w as found to be 0.1 s-1. The solubilities of ethylene,

CO , a n d H 2 in toluene and w at er were measured usinga pressure absorption method, and the values are givenin Ta ble 2. The values of   R 1,   R 2, a n d   R 3   as defined byChaudhari and Doraiswamy (1974) were calculated.

These were found to be less than 0.12, even for thehighest ra tes observed. This confirms t he a bsence ofmass-transfer limitations and, hence, the kinetic regime.For the purpose of kinetic modeling t he dat a at consta ntcata lyst concentra t ion were used in either case.

A n u mber of e mpirica l mode ls we re e xa min e d t or ep re se nt t h e ob se rv ed d a t a . Th e b es t m od el w a sselected on the basis of the criteria of least average errorbe t we e n t h e p re dic t e d a n d e x p e rime n t a l ra t e s (φmi n)defined a s

and the results are presented in Table 3 for the studiesin toluene medium. The values of the consta nts w eree v a lu a t e d u s in g a n o p t imiza t io n ro u t in e ( M a rq u a rdtme t h od). F or t h is p u rp os e in i t ia l g u e s s v a lu es we reobta ined by the gra phical f it t ing of the rate da ta to there sp ect iv e mo de ls . Th e se v a lu es we re u s e d a s t h estart ing values for the optimizat ion program.

The model 5 could not be considered because it givesa negative value for para meter K E . Also the trend withk  is not a ccording to tha t dictat ed by thermodynamics.Similarly models 3, 4, and 6 have inconsistent trendsi n t h e p a r a m e t e r s   K B   a nd   K E   a n d h e n c e w e r e n o tconsidered. B etween the models 1 an d 2, the φmin  valueswere higher for model 2.

Table 3. Models Examined To Fit the Data on Ethylene Hydroformylation

m odel r a t e m odel   T , K   K B   × 10-2 K E   k    φmi na 

1 k (A *)1.5

B *E *

(1 + K B B *)2

(1 + K E E *)

333 1.116 15.01 8.202 × 102 3.95 × 10-11

353 1.268 23.97 8.873 × 103 2.12 × 10-10

373 1.490 26.74 3.007 × 104 1.00 × 10-9

2   k (A *)B *E *

(1 + K B B *)2

(1 + K E E *)2

333 1.000 26.47 2.920 × 102 2.350 × 10-10

353 1.530 28.56 2.208 × 103 3.904 × 10-9

373 1.820 58.84 1.520 × 104 7.140 × 10-9

3 k (A *)1.5

B *E *

(1 + K B

B *)2

(1 + K E

E *)

333 0.944 27.69 1.490 × 102 3.830 × 10-10

353 1.290 48.86 2.410 × 103 3.790 × 10-9

373 1.780 43.45 1.704 × 104

2.350 × 10-8

4 k (A *)1.5

B *E *

(1 + K B B *)(1 + K E E *)2

333 1.380 26.50 2.640 × 102 1.430 × 10-9

353 1.010 47.71 2.830 × 103 3.180 × 10-9

373 0.153 27.99 4.718 × 103 8.180 × 10-6

5 k (A *)1.5

B *E *

(1 + K B B *)3

(1 + K E E *)

333 0.413 20.10 9.410 × 102 7.720 × 10-11

353 0.375   -48.61 9.780 × 103 2.020 × 10-9

373 0.009 42.20 2.880 × 103 2.210 × 10-8

6 k (A *)1.5

B *E *

(1 + K B B *)3

(1 + K E E *)

333 0.924 16.98 5.630 × 102 1.260 × 10-9

353 1.268 23.97 8.870 × 103 1.090 × 10-8

373 0.023 645.79 2.190 × 104 2.020 × 10-8

a  φmi n   is minimized sum of t he squa res of the difference between observed an d predicted ra tes.

Figure 10.  E ffect of the part ia l pressure of ethylene on th e rateof reaction in an a queous medium. Reaction conditions:   P H 2

, 0.689M P a ;   P CO , 0.689 MPa; concentrat ion of catalyst , 5   ×   10-4 kmolm-3; Rh /TP P TS, 1:6; t emperat ure, 313 K.

R 1 )  R 

k 1aA *  (4)

R 2 )  R 

k LaB *  (5)

R 3 )  R 

k LaE *  (6)

φmi n  )∑i )1

n 

(R pred  - R obs )2

(7)

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The model chosen on the basis of   φmi n  w a s

Th is mo del w a s f ou n d t o p re dict t h e ra t e da t a wit h inan error of   (8%, w hich is w ithin t he ra nge of experi-mental error. This wa s found to be in excellent a gree-ment w ith th e predicted ra tes, as is clear from t he low φmi n   value. The values of  k ,  K B , a n d   K E  were evalua ted

for a ll three tempera tures a nd a re given in Table 3. Theactivat ion energy wa s calculated a s 9.4  × 104 kJ /km ol.

A similar exercise was undertaken for arriving at ara te model for reaction in a n aq ueous medium. The rat edat a obta ined were found to be w ell represented by thefollowing form of rat e equat ion.

In this case the model similar to model 2 (Table 3)wa s found to best f it the observed ra te dat a. A modelsimilar to model 1 (1.5 order with respect to   A *) couldnot predict the rate part icularly for hydrogen depen-dence.

Conclusions

The kinetics of hy droformylat ion of ethylene wa ss t u died in t o lu en e a n d wa t e r me dia u s in g H R h (CO )-(PPh 3)3 and [Rh(COD)Cl]2/TP P TS cat a lyst , respectiv ely.The rates were found to have a first-order dependencewith respect to cat alyst concentra t ion. Similar tr endswere observed with respect to the part ial pressure ofethylene and carbon monoxide, in both solvents. Thedifference in the locat ion of the ma xima w as at tributedt o t h e p oor s ol ub il it y of t h e r e a c t a n t s i n w a t e r a scompa red to toluene. The ma jor difference observed wa sa 1.5 order w ith hyd rogen in t oluene versus a first orderin wa t e r .

The following ra te model were found t o represent t hedata in toluene at 333-373 K:

The following ra te model represented th e dat a in a naqueous system at 313 K:

within 8%error.

Nomenclature

A *   )   concentration of H 2   i n t o l u e n e o r w a t e r a t a g a s-liquid int erfa ce, kmol/m 3

B *   )   concent ra t ion of CO in t oluene or w a t er a t a ga s-liquid int erfa ce, kmol/m 3

E *   )   concent ra t ion of et hylene in t oluene or w a t er a t aga s-liquid int erfa ce, kmol/m 3

k   )  rea ct ion ra t e cons t a nt in eq 8, m7.5 kmol-2.5 s-1

K B   ) cons t a nt in eq 8, m 3 kmol-1

K E   ) cons t a nt in eq 8, m 3 kmol-1

P  ) t ot a l pres s ure in t he rea ct or a t a ny t ime minus va porpressure, MPa

P 0 ) initial pressure in the reactor minus vapor pressure,MP a

R   ) g a s c on s t a n t , M P a m 3 kmol-1 K-1

T   )  t empera t ure of t he ga s in t he r ea ct or , K

V L  )  liquid volume in the reactor, m 3

V G   )  void space in the reactor, m 3

Z   ) compressibility factor

Literature Cited

Ar a i , H . ; K a n e k o, T. ; K u n u g i , T. Ca t a ly t ic v a p or p h a s e h y d r o-formylation of olefins over polymer immobilized rhodium com-plexes.   Chem. Lett.  1975, 265-268.

Chaudhari, R. V.; Doraiswamy, L. K. Simultaneous absorption andreaction of tw o gases in a liquid/format ion of ethyl chloride fromethylene an d hydr ogen chloride. Chem. Eng. Sci. 1974,  2 9 , 349-

354.Ch a u d h a r i , R . V . ; G h ola p , R . V . ; Em ig , E. ; H of f m a n n , H . G a s-

liquid mass tra nsfer in “Dead-End” a utoclave reactors.  Ca n . J .

Chem. Eng.  1987,   65 , 744-751.

Cornils , B. ; Wiebus, E. Aqueous catalyst for organic react ions.C H E M T E C H    1995,   25 , 33-38.

Cor n ils , B . ; Wieb u s E. Vir t u a l ly n o e n v ir on m e n t a l im pa c t : t h ebiphasic oxo process.   Re cl . T r a v . Ch i m . P a y s- B a s    1996,   115 ,211-215.

Deshpande, R. M.; Ch audha ri, R. V. Kinetics of hydroformylat ionof l-hexene using HRh(CO)(PPh 3)3  complex cata lyst .  I n d . E n g .

Chem. Res.  1988, 27,  1996-2002.

D iv ek a r , S . S . ; D e s h pa n d e , R . M . ; C h a u d h a r i , R . V . K in et ics ofhydroformylat ion of 1-decene using homogeneous HRh(CO)-( P P h 3)3 catalyst : A molecular level approach.  Catal. Lett. 1993,21 , 191-200.

Eva ns, D.; Osborne, J . ; Wilkinson, G. Hy droformylat ion of alkenesby use of rhodium complex catalysts .   J . Ch e m. S o c . A   1968,3133-3142.

King, R. B .; King, A. D.; J r., Iqba l, M. Z.; Tana ka, K. In termediat esin the rhodium catalysed hydroformylation of olefins.  A n n . N. Y .

Acad. Sci.  1980,   333 , 74-79.

Polievka, M.; Uhla r, L. ; Ma cho, V. Hydroformylat ion of ethylenecatalyzed by rhodium complexes.   Petrochimia   1980,   20 , 33-41.

Schwaar, R. H. SRI-PEP Report 11DS, 1991.

Taka hashi, N.; Takeyama , T.; Yana gibashi, T.; Taka da, Y. Com-parison of penta n-3-one formation w ith propionaldehyde forma-tion during ethylene hydr oformyla t ion over rhodium/activecarbon catalyst .   J . C a t a l .  1992,   531 , 1936-1938.

Received for review   J uly 11, 1997Revised ma nu scri pt received   February 12, 1998

Accepted    February 12, 1998

IE970497U

R  )  k A *1.5

B *E *

(1 + K B B *)2(1 + K E E *)2  (8)

R  )  34550A *B *E *

(1 + 278B *)2(1 + 3829E *)2  (9)

R  )  k A *

1.5B *E *

(1 + K B B *)2(1 + K E E *)

2

R  )  34550A *B *E *

(1 + 278B *)2(1 + 3829E *)

2

2396   Ind. E ng. C hem. Res. , Vol. 37, No. 6, 1998