Hydration of olefins on zeolite catalysts

216

KH. M. MI~AOm~v et al.

m e r i z e d in olefm on r h e n i u m oxide c a t a l y s t s to f o r m a n equilibrium m i x t u r e o f n - b u t e n e s which is t h e n s u b j e c t e d to d i s p r o p o r t i o n a t i o n . SUMMARY

1. I n the presence of a Re~O7 c a t a l y s t p r o p y l e n e is selectively t r a n s f o r m e d into a n e q u i m o l e c u l a r m i x t u r e of ethylene a n d n - b u t e n e s . 2. Owing to t h e high isomerization ability of t h e c a t a l y s t b u t - 1 - e n e f o r m s a n equilibrium m i x t u r e of n - b u t e n e s which undergoes d i s p r o p o r t i o n a t i o n t o p r o p y l e n e a n d pentenes. T h e l a t t e r are p a r t i a l l y p o l y m e r i z e d on t h e c a t a l y s t . 3. S a t u r a t i o n of a n a t u r a l carrier w i t h a r h e n i u m h e p t o x i d c solution in d i o x a n increases t h e a c t i v i t y , selectivity a n d s t a b i l i t y of t h e r h e n i u m o x i d e c a t a l y s t d u r i n g d i s p r o p o r t i o n a t i o n of olefms. REFERENCES

1. Yu. N. USOV, Ye. V. SKVORTSOVA, T. G. VAISTUB and E. V. PLETNEVA, Neftekhimiya 12, 223, 1972 2. Kh. M. MINACHEV, M. A. RYASHENTSEVA, G. V. ISAGULYANTS and N. N. ROZHDESTVENSKAYA, Izv. AN SSSR, ser. khim., 705, 1972 3. V. Sh. FEL'DBLYUM, T. I. BARANOVA, T. A. TSAILINGOL'D and V. A. PETRUSHANSKAYA, Zh. organ, khimii 9, 878, 1973 4. Brit. Patent 1.106.016, 1968; RZhKhim. 13P, 14P, 1968 5. Auth. Cert. U.S.S.R. 407572, 1973. Otkr. izobr., prom. obr. i toy. znaki No. 47, 1973 6. Brit. Patent 1.105.563, 1968, RZhKhim. llN, 10P, 1969 7. M. A. RYASHENTSEVA and Yu. A. AFANAS'YEVA, Zh. analit, khimii 16, 108, 1961 8. I. K. KUCHKAYEVA, Kand. dis. Saratovsk. gos. un-t (Post-Gra4uate Thesis, Saratov University). 1969 9. Yu. N. USOV, Ye. V. SKVORTSOVA and E. V. PLETNEVA, Neftekhimiya 14, 368, 1974 10. H. S. BRODBENT, J. Organ. Chem. 24, 1847, 1959

HYDRATION OF 0LEFINS ON ZEOLITE CATALYSTS* K ~ . M. MI~ACHEV, YE. S. MORTIKOV, A. A. MASLOBOYEV, N. F. K o x o I ~ o v a n d L. V. TOLKACHEVA N. D. Zclinskii Institute of Organic Chemistry, U.S.S.R. Academy of Sciences

(Received 24 May 1976) SII~CE olefins were h y d r a t e d for t h e first t i m e in t h e presence of s u l p h u r i e acid [1] m a n y c a t a l y s t s were p r o p o s e d for t h i s reaction, which is so i m p o r t a n t * Neftekhimiya 16, No. 6, 846-852, 1976.

i

Hydration of olefins on zeolite catalysts

217

from an industrial point of view. Phosphoric acid on a solid carrier [2], polytungsten compounds [2, 3] and wide-pore sulpho-cation resins [4] are among the most effective catalysts of direct hydration. H o w e v e r , the use of phosphoric and other acids causes corrosion of the apparatus, acid consumption during the process and the formation of waste water. Catalysts based on tungsten oxides, the same w a y as amorphous aluminosilicates [5], are characterized b y comparatively low olefm conversion under rigid process conditions (200260 °, 140-170 arm). Having low heat stability, cation-exchange resins do not enable the process to be intensified b y raising temperature, which impedes hydration of olefins with low reactivity, e.g. ethylene. Having cation-exchange properties, high surface acidity and heat stability, zeolites can be used successfully for olefin hydration. However, only a few papers have been published so far in connection with this problem [6-9]. Natural clinoptilolite and mordenite treated with ammonium chloride are proposed as catalysts in a patent previously described [7]. At 210 ° and 80 atm, with a molar ratio of ethylene : water of 55 : 1 ethanol concentration in the liquid catalysate reached 6.1 ~/o wt. Nitta [8] examined the relative activity of/k-type zeolites in ethylene hydration in a static system at 220-300 °. Activity was evaluated according to the reduction of pressure in the system from 610 mm to 355 mmHg. /k s t u d y is made in this paper of the possible use of synthetic Y type zeolite with cations of calcium, rare-earth elements (REE) and chromium as catalysts in hydration of ethylene, propylene and butenes [6]. EXPERIMENTAL

A layout of the apparatus is shown in the Figure. Distilled water was supplied b y plunger pump 2. Olefms were supplied at constant rate with transmitter 5, the lower cylinder of which was filled with oil using pump 3. /k second transmitter was provided for the continuous feed of olefin. The reaction took place in isothermal continuous reactor 7, 1.5 m high and 20 mm in internal diameter, the upper part being used for preheating the raw material. Part of the experiments was carried out in apparatus 8 with an operating volume of 300 cm 3 with a stirrer and dispersed catalyst. 100 cm 3 or 70 g catalyst was placed into the reactor. Pressure in the reactor and transmitter was maintained automatically using regulators 6. The catalyst was regenerated after every experiment b y passing through air at 500 ° , the waste gases containing CO2, in order to examine coke formation. The catalysate obtained as a result of hydration and initial and unreacted gases were analysed using an LKhM-8M chromatograph with a flame-ionization detector and capillary column 65 m long with triethylene glycol dibutyrate as stationary phase and nitrogen as carrier gas. Alcohols were analysed at 85 ° and a pressure of 3 arm, gases at 20 ° and 2 arm. The amount of alcohol in the catalysate was determined b y the "internal standard" method using

218

KH. M. MII'CACHEVet a/.

acetone. The alcohols were identified by the addition of a pure standard sample and from I R spectra of the product separated. Alcohols were separated by rectification of the upper organic layer obtained on adding potash to the eatalysate. A Khrom-3 chromatograph with a preparatory column 5 m long was used in some cases for the separation of alcohols. Ethylene of 99% purity, propylene of 95.5% purity containing about 5~o propane, ethane and other hydrocarbons were used for the experiments.

lq

Layout of apparatus used for direct hydration of olefins on zeolite catalysts. /--Water container; 2--water pump; 3--oil pump; 4--oil container, 5--transmitters for olefin feed; 6--pressure regulators; 7--reactor for the stationary catalyst layer; 8--reactor with a mixing equipment; 9---filters; 10--separator; 11--gas meter; 12--blower; 13--system for the purification of air and nitrogen; 14--cylinder for the initial olefin. n-Butenes and isobutene of 96 and 99% purity, respectively were obtained by dehydration of corresponding alcohols on alumina. The butane-butylene fraction was not purified from sulphur compounds. The composition of fractions (%) was as follows: 20-6 isobutene and 20-9 n-butenes, 31.9 isobutane and 15.7 n-butane, the remainder being propane, propylene and isopentane: H~S content was 0.2 mg/100 cm 3 gas. NaY zeolite in granules without a binder with a ratio of SiO2 : A120a of 3"6 and powdered zeolite with a ratio of Si02 :Al~08 of 4.7 were used for preparing the catalysts. Powdered zeolite was treated with aluminium hydroxide and chromic hydroxide by a method previously described [10]. Cation

Hydration of olefins on zeolite catalysts

219

exchange was carried out b y the t r e a t m e n t of zeolite with t h e solution o f a corresponding salt, followed b y washing, d r y i n g a n d calcination [11]. T h e a c i d i t y of samples was d e t e r m i n e d b y t i t r a t i o n with b u t y l a m i n e . Characteristics of catalyst samples are given in Table 1. T A B L E l . C H A R A C T E R I S T I C S OF ZEOLITE CATALYSTS

No.

of sample 1 2 3* 4* 5 6* 6 7 8 9 10

Zeolite

CaY CaY ] CaREEY CaREEY ! CaREEY CaREEY CaREECrY ii CaREECrY CaCrY CaY CaY

11

CaREECrY

12 •

NaY

Binder, %

30 AliO8 w.b. 30 A1203 30 A1208 16 Ai203 w.b. 30 A12Os w.b. 16 A1208 30 CrtOs 20 Cr20,/ 10 AlsOsJ 10 Cr~Os/ 20 Al~Osj 30 Cr~Os

Overall I Dim- I SiO, : degree ension Bulk AI,Oa of ex- I of I denmole/ change, granu- [ sity, /mole equiv.% les, mm g/cm3

Acidity, mequiv./ Strength,

/g

kg/mm'

4-7 3.6 4"7 4.7 4.7 3"6 3.6 3.6 4.7 4.7 4.7

90 80 87 90 87 78 3. 6 80 90 90 87

4X5 5X6 4X5 4X5 4X4 5X6 4×5 5X6 4X4 4X5 4X5

0"68 0"60 0"65 0"68 0"70 0"60 0"65 0"60 0"70 0"65 0'68

0-48 0"40 0"76 0"86 0"85 0"82 0"82 0"72 0"50

0.5 1.8 0-5 0.5 0.3 1.2 0.5 1.2 0.2 0.1 0.1

4"7

87

4×5

0"68

0.56

0.3

4x5

0.70

0.2

0.1

4.7

* Degree of exchange to R E E is a p p r o x i m a t e l y 50 equiv.%. * Degree of exchange to R E E is approximately 80 equiv.%

E q u i l i b r i u m concentrations were calculated for t h e h y d r a t i o n o f e t h y l e n e , p r o p y l e n e and b u t e n e s using constants proposed b y Vvedenskii [12]. RESULTS

Zeolite w i t h a sodium cation was completely inactive in h y d r a t i o n e v e n a t a pressure o f 200 arm. Samples with calcium cations (Nos. 1 a n d 2, Table 1) a p p e a r e d to be of low activity. I n p r o p y l e n e h y d r a t i o n the yield o f isopropyl alcohol was n o t more t h a n a fraction o f 1 per cent. More reactive isobutylene u n d e r strict conditions (120 arm, 200 °) a n d a molar ratio o f w a t e r :olefin o f 6 : 1 was t r a n s f o r m e d into t e r t - b u t a n o l to the e x t e n t o f a p p r o x i m a t e l y 1%. CaY zeolite w i t h a ratio o f Si02 : AlcOa o f 4.7 (sample No. 2) a p p e a r e d t o be s o m e w h a t more active t h a n with a ratio o f 3.6 (sample No. 1). The a c t i v i t y o f zeolite catalysts increased suddenly on exchanging Na cations b y R E E . I n t h e m e a n t i m e the zeolite o b t a i n e d d i r e c t l y b y the exchange o f N a Y zeolite has become irreversibly inactive during the experiment. Samples l~os. 3 - 6 containing calcium a n d R E E cations at t h e same t i m e h a d a higher stability.

K~. M. MrsAcm~v e$ a/.

220

The ratio of SiOs : A1,Os in the range of 3.6-4.7 in R E E zeolites had practically no effect on tert-butanol yield, which was 15-17% for both samples with a degree of exchange by R E E of 50% at 90 a t m and 200 ° with an efficiency of 0.070 g/hr., cm a. With an increase of the degree of exchange b y R E E of up to 80°/0 and with a ratio of water : isobutene of 5 : 1, alcohol yield increased to 20% with an efficiency of up to 0.075 g/hr. cm 3, which corresponds to 40% of the equilibrium value. Alcohol yield in ethylene and propylene hydration at 280 ° and 80 atm is 6-10°//o (less t h a n 3 0 o of equilibrium values). During hydration of olefins on a zeolite catalyst there is always a " m a , turing" period, which depends on process conditions and the type of catalyst and normally lasts for 2-3 hr. Using isobutene, which is the most reactive of the olefins tested, it can be seen t h a t the activity of zeolite with R E E (Table 2) T~LE 2.

EFFECT

OF T E M P E R A T U R E , PRESSURE AND RE.~GENT RATIO O1~~ HYDRATIOlq

CaRREY CATALYST Sample No. 4, average value in 6 hr

OF I S O B U T E N E ON A

T,

°C

200

Pressure, arm 120

Alcohol Water : olecontent fin, in catalysate, mole/mole %wt, 1 :

3: 6: 9: 200

90

9:

6:

200 100 150 250 300

60 30 120

6:1

Output, g/hr. cms

Alcohol yield, wt. ~o

12'5 11.4 9"2 9.4

0.072 0-071 0.068 0.068

12.5 16.6 20.5 26.7

8.3 10.3

0.058 0.067

24"4 22"9

7.3 4.5

0,040 0.032 Traces 0.048 0.052 0.036

16"2 10"4

6:1 6.0 8.1 4.2

13"3 18"0 12"9

only begins to show at 150 ° and a pressure of at least 30 atm and tert-butanol yield reaches 10% in this case. For sample No. 4 the optimum values are 90 arm and 200 °. I t is inadvisable to increase temperature and pressure above these limits. A variation of the water : olefin ratio has only a slight effect on alcohol concentration in the catalysate. Maximum reaction rates vary little with a change in the amount of olefin, being in the range of 0.068 to 0.072 g / h r . c m 3. This effect is, apparently, due to the limitation of the stage of olefm adsorption, e. g. on R E E cations. I t could therefore be expected t h a t catalysts containing chromium charac-

Hydration of oleflns on zeolite oatalysts

221

terized b y a high heat of adsorption of olefm, will have i n c r e s ~ l activity in relation to hydration, as observed during polymerization of ethylene [13]. Samples Nos. 6-12 (Table 1), characterized b y the presence of trivalent chromium both in the cationic form and as hydroxide (Table 3) were therefore tested under the conditions selected. All samples containing chromium appeared to be much more active t h a n samples free from chromium. Chromium catalysts were already fairly active T~sLE

3. A C T I V I T Y OF Z E O L I T E CATALYSTS C O N T A I N I N G CHROMIUM AT 2 0 0 °

Space velocity 1 hr-1; H t O : isobutene=6 : 1; pressurre 30--60 atm. Average value in 6 hr No. of Concen sample Pres - tration, Output, Yield, (accordsure~ g/hr × Type oi" zeolite of ing to arm BuOH, %wt. X cmt %wt. Table 1)

10 11

CaREECrY+ 30% AlsOa CaREECrY, w.b. CaCrY+ 16% AlIO= CaY+ 30% CrOs CaY+20% CrtOs+ 10% AltO s CaREECrY+ 10% CrsOs+20% g-l=Os

12

NaY+ 30% Cr,Os

6

7 8 9

60 50 60 90 60 60 60 30* 90

12"4 14.7 7.2 2-3 2"7 20"8 17.0 13.7 0.3

27.5 32.6 15"9

5"1 6"0 46.1 37.7 30"4 0"7

0,070 0.073 0-032 0.010 0.012 0.090 0.082 0.071 0.001

• Temperature 150 o.

at 30-60 arm instead of 90-200 arm required for rare-earth zeolites. The presence of chromium in cationic form somewhat increased alcohol yield, compared with the oxide form: b y 15.9% for sample No. 8 and 5.1% for sample No. 9, respectively. Catalysts obtained b y simply mixing chromic hydroxide in a proportion of 30% (samples Nos. 9 and 12) with zeolite were characterized b y low mechanical strength and were therefore unsuitable for prolonged use. The addition of 10-20% aluminium hydroxide, as well as chromic hydroxide, considerably improves the strength of the catalyst (samples Nos. l0 and 11). B y increasing surface acidity, cations of R E E ensured higher activity than calcium cations in samples containing chromium. Sample No. 11, containing c h r o m i u m in cationic form and as oxide, as well as cations of calcium and R E E , showed particularly high activity. The concentration of tert-butanol in the eatalysate reached 17% at 30 arm and 20.8% at 60 atm, which is fairly close to the equilibrium value (25%). Tert-butanol yield under these conditions was 46-1% of theory and output was up to 0.09 g/hr.cm 8. Ethanol concentration in the catalysate reached 6% wt. with a yield of 17.6% on this catalyst at 80 arm and 250 ° and with a water : ethylene ratio of 6 : 1. This value was 44% of the equilibrium value. On reducing temperature to 150-200 ° alcohol concentration was reduced to 1%, however, approximately the same a m o u n t

222

KH.

M.

MINACHEV

et al.

of sec-butanol formed apparently by dimerization of ethylene, followed by the hydration of the n-butene formed. Activity variation on various catalyst samples m a y be explained if we assume t h a t hydration takes place by a two-stage mechanism with olefin adsorption on cations, particularly chromium cations, followed by hydration on a c i d centres of the zeolite lattice. This is confirmed by a higher activity of zeolites containing chromium contributing to olefin adsorption together with acid forms of R E E Y type zeolite and low activity of the NaY sample with chromic oxide without sufficient acid, i.e. hydrating action. Hydration on zeolites may be used to separate isobutene from n-butenes b y selective hydration of isobutene. During hydration of a butane-butylene fraction containing about 20% n-butenes and the same amount of isobutene, selectivity in relation to tert-butanol decreases on zeolites with R E E with an increase of temperature and is about 700/o at 250 ° and 200 arm. The catalyst containing chromium ensured 100~/o selectivity in the entire temperature range of 150-200 ° and pressure range of 60-200 arm and m a y therefore be used for selective isolation of isobutene (Table 4). Hydration on zeolite TABLE 4. HYDRATION OF A BUTANE-BUTYLENE FRACTION ON CATALYSTS

CaREEY AND CaCrREEY

60-200 arm; 150-300 °C; water : butenes=5 : 1

T, °C

l:~ressure~

atrn

150 200 200 250 300 350

200 100 200 200 200 200

Butanol yield

Selectiv ity,

sec- I tert-

%

CaREEY -10.5 0.9 9.4 1.5 9.9 5.1 13.3 6.5 9.6 2.2 4.3

100 91 89 72 60 62

OutI Presput, oC sure g/hr. T, • arm • em3

see- I tert-

~o

"cma

60 50 90 120 200

CaCrREEY 11.5 27.4 18.8 27.8 17.5

100 100 100 100 100

0.012 0.028 0.022 0.030 0.018

0.01211 0.01411 0.01211 0.01611

150 200 200 200

0.012] 200 0.005

Butanol yield

Sele- Outctiv- p u t , ity, g/hr.

catalysts is combined with the simultaneous desulphurization of the butane-butylene fraction. I t m a y be assumed t h a t dissolving olefin in water under the conditions studied is not a limiting stage. This is confirmed by special experiments cartied out in a reactor with a stationary catalyst layer and in a reactor with mixing, producing about the same results. Similar results were also obtained when adding acetone as solvent, in which both water and olefin dissolves. With prolonged operation at high pressure, the mechanical strength of zeolites with cations of calcium of R E E increases several times, which formed ~he basis for developing the process of increasing the mechanical strength of catalysts and adsorbents [14].

Hydration of olefins on zeolite catalysts

223

SUMMARY 1. A s t u d y was m a d e of direct h y d r a t i o n of C~-C4 olefins on zeolite c a t a lysts c o n t a i n i n g calcium, r a r e - e a r t h elements a n d c h r o m i u m in cationic f o r m a n d c h r o m i u m a n d a l u m i n i u m in t h e f o r m of h y d r o x i d e in the t e m p e r a t u r e range of 150-300 ° a n d pressure range of 30-200 arm. 2. I t was shown t h a t zeolites c o n t a i n i n g c h r o m i u m t o g e t h e r with r a r e - e a r t h elements are h i g h l y active, alcohol yield a t 200 ° a n d 60 a r m reaching 461~/o REFERENCES

1. A. M. BUTLEROV, Izbr. raboty po organ, khimii. (Selected Studies of Organic Chemistry). Izd. AN SSSR, Moscow, 1951 2. F. AZINGER, Khimiya i tekhnologiya monoolefmov (Chemistry and Technology of Mono-olefins). Gostoptekhizdat, Moscow, 1960 3. A. SUMIO, Chem. Engng. 80, 56, 1973 4. A. T. MENYAILO, Sintez spirtov i organ, produktov iz heft. uglevodorodov (Synthesis of Alcohols and Organic Products from Petroleum Hydrocarbons). Tr. l~lIISa, 2, Goskhimizdat, Moscow, 1960 5. U.S.A. Patent 3 548 013, 15.12.1970. Chem. Abstr. 73, 87368, 1971 6. Auth. Cert. U.S.S.R., 405, 321, 05.05.1971 7. Japanese Patent 72045323, 15.11.1972; Chem. Abstrs 15, 57738 m, 1973 8. M. NITTA, K. TANABE and H. HATTORI, J. Petrol. Inst. Japan 15, 113, 1972 9. Patent of the German Democratic Republic, 113 344, 01.08.1974 10. Auth. Cert. U.S.S.R., 254 488, 01.03.1968; Otkr. isobr, prom. obr. i toy. znaki, No. 32, 20, 1969 11. Auth. Cert. U.S.S.R. 303 095, 18.08.1969; Otkr., izobr., prom. obr. i toy. znaki, No. 16, 28, 1971 12. Termodinamicheskiye raschety neftekhimicheskikh protsessov (Thermodynamic Calculations Related to Petrochemical Processes). Gostoptekhizdat, Leningrad, 1960 13. Kh. M. MINACHEV, Ye. S. MORTIKOV, A. A. MASLOBOYEV, A. A. LEONT'YEV, N. F. KONONOV and N. V. MIRZABEKOVA, Izv. AN SSSR, ser. khim., 1785, 1976 14. U.S.A. Patent 3 764 563, 30.03.1972