TRANSFORMATION OF DI,CYCLOPENTYL ON Pd-, Co-

AND Ni-ALUMINA CATALYSTS UNDER CATALYTIC

REFORMING CONDITIONS

(UDC 542.97+ 542.973)

N. I . S h u i k i n a n d I . I. V o z n e s e n s k a y a

N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences, USSR

Translated from Izvest iya Akademii Nauk SSSR, 8eriya Khimicheskaya, No. 12,

pp. 2200-2202, December , 1965

Original ar t ic le submitted April 5, 1965

A number of authors have shown that d icyc lopenty l on certain catalysts is capable of isomerizing to the deca l in

system, while hydrogenolysis of one or both of its cyclopentane rings occurs on other catalysts. The isomerizat ion of cyc lopenty lcyc lopentanol to t rans-decal in under the influence of hydriodic acid was observed by Zelinskii and co -

workers [1]. This same alcohol is isomerized to the octa l in system under the influence of zinc chloride [2] or phos- phoric acid [3]. Dicyclopentyl i tself is easi ly converted to deca l in in the presence of aluminum chloride [3]. Under

ca t a ly t i c reforming conditions, a s imi lar isomerizat ion of d icyclopentyl occurs on plat inized alumina, with a sub- sequent dehydrogenat ion of the formed deca l in to te t ra l in and naphthalene, which was shown by one of us [4]. The

hydrogenolysis of d ieyctopenty l under the influence of A1C13 under cracking conditions, with the formation of paraffin, pentamethylene and hexamethylene hydrocarbons (the lat ter were obtained as the result of isomerizat ion of the penta -

methylene hydrocarbons) was observed by Yur'ev and Levina [5]. Analogous results were obtained by Eventova on

pla t in ized carbon [6].

As had been shown by one of us [7], on skeletal N i -A1 catalyst only one f ive-membered ring in the d i cyc lo -

pentyl molecu le undergoes hydrogenolysis with the formation of various alkylcyclopentanes.

In this paper we studied the transformations of d icyclopenty l on 0.5% Pd/AIRO 3, 10% Co/A1203 and 10%o Ni/ A1203 catalysts under reforming conditions. In the presence of these catalyst , d icyclopentyl was isomerized to decalin, which then underwent dehydrogenation to te t ra l in and naphthalene. Besides isomerization, the dieyclopentyl mole -

cule undergoes hydrogenolysis on Co- and Ni-a lumina catalysts.

E X P E R I M E N T A L

20 1.4650; d~ ~ The starting d icyc lopenty l was synthesized by us as described in [8]. It had b. p. 78 ~ (20 mm); n D 2o 1.4648; d24 ~ 0.8669. The experiments were run in an apparatus 0.8656. Literature data [8]: b. p. 188 ~ (765 ram); n D

of the flow type [9] at 450 ~ and a hydrogen pressure of 30 atm, and also at atmospheric pressure in a hydrogen stream

in order to ascertain the effect of pressure on the yield of the transformation products, in the presence of 50 mI of 0.5% Pd/AlzOa, and 10% Co/AleO 3 or Ni/A1203. The d icyclopenty l was passed through the apparatus at a space ve l - oci ty of 0. 3 h -I, and a 5 : 1 molar rat io of hydrogen to hydrocarbon. The obtained ca ta lyzates were subjected to

fract ional d is t i l la t ion through a column with an eff iciency of 30 theoret ical plates. The fractions were investigated by the gas- l iquid chromatographic and spectral analysis methods. The chromatographic analysis was run using a 5- meter column, which was fi l led with d ia tomi te having a granule size of 0.25-0.5 ram, on which was deposited 20 wt. %o of poly(ethylene glycol adipate). The carrier gas was hel ium. The analyses were run at 118 ~ and 198 ~ and carr ier gas rates of 30 and 60 ml /min , respectively. The naphthalene formed during the react ion process was iso- lated from the ca ta lyzates by freezing and had m. p. 79.9% The yields of the cata lyzates , obtained on the various catalysts , and their composit ion are given in Table 1; the composit ion of the vent gases is given in Table 2.

[__/ N~__JRaney Ni

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TABLE 1. Amount of Hydrocarbons in Catalyzates, Weight %

Hydrocarbons

0,50; Pd/A!=o~ ! ,0% co/At~o~ [. a t m o s - 1

30atm pheric t 3oatm pheric I pressure t pressure I

I0% Ni/Al2Oa

t a tmos- 3e atm I pheric

Ipressure

yield of catalyzate based

Cyclopentane Methylcyclopentane Ethytcyclopentane Propylcyclopentane Benzene Toluene CIoHz2 hydrocarbons

Trans-decalin Cis-decalin Tetralin Naphthalene Unchanged dicyclo-

penty'l

79,8 83,5

2,0 / I ,0

8,0 2,0 1 ,0 1 ,0

I2,0 6,0 45,0 7,0 32,0 83,0

on passed dicyclopentyl, % 73,8 1,0 5,0 3,0 7,0 1,0 2,0 7,0

6,0 3,0 2,0

12,0 5 1 , 0

90,0 50,0 62,0

t 2,0 1,0 - -

1 ,0 1 ,0 2,0 1,0 1,0 1,0

2,0 1,0 -- 2,0 3,0 2,0 6,0 1,0 2,0 3,0 2,0 2,0

86,0 87,0 N,0

TABLE 2. Composition of Vent Gases, %

Gases

H2 CH4

0,50,~ ed/Al:O2 i0% CotAhO~

atmos - I atmos - 30 atm pheric I 3oatm pheric

Ipressurel I pressur~

100 I 100 60 [ 97g - - - - 40

10% Ni/AI203

almos- 30 arm pheric

}ressnre

12 23 88 77

From the presented data it can be seen that the greatest isomerizing action is possessed by the palladium cata- lyst. It also possesses the greatest selectivity, since the transformation products consist of decalin, tetralin and naph-

thalene (the latter predominates), while the cleavage products of the five-membered rings constitute a total of only

i-2%. There was no cleavage of methane on this catalyst. A greater variety of transformation products is obtained

in the presence of the cobalt catalyst. Besides naphthalene, tetralin and decaiin, the catalyzate contained a sub-

stantial amount of alkylcyclopentanes and isodecane, which were formed as the result of the hydrogenolysis of one

of the two cyclopentane rings. In the given case, besides hydrogenolysis, demethylation of the formed alkylcyclo-

pentanes apparently also took place. Both the composition of the hydrogenolysis products and the presence of meth-

ane in the vent gas indicates this. In addition, the alkylcyclopentanes underwent isomerization with an expansion

of the ring and subsequent dehydrogenation, as a result of which benzene and toluene were obtained.

The nickel catalyst possessed the lowest isomerizing properties and ability to effect hydrogenolysis. In their

composition, the transformation products of dicyclopentyl on this catalyst were analogous to the products obtained

on the cobalt catalyst, but they were formed in a smaller amount. A somewhat greater amount of the cis-form of decalin was formed on the nickel catalyst, whereas the ~ans-form of decalin was obtained mainly on the palladium and cobalt catalysts. Intense methane cleavage occurred on the nickel catalyst. On comparing the results obtained in the experiments run under hydrogen pressure and at atmospheric pressure it can be seen that the yield of the trans- formation products was sharply reduced in the experiments run at atmospheric pressure. The dehydrogenation of the formed decalin went to a lesser degree. All of this indicates the important role played by pressure in the progress of the investigated transformations.

SUMMARY

1. A study was made of the transformations of dicyclopentyl on 0.5~ Pd/AizOs, 10% Co/AlzO a and 10% Ni/AlzO a catalysts under reforming conditions.

2. The principal transformation of dicyclopentyl under the adopted conditions (450 ~ space velocity 0.3 h -1) is its isomerization to the condensed decalin system, which is then dehydrogenated to tetralin and naphthalene. This direction is especially characteristic for the transformations proceeding under the influence of the Pd-alumina cata-

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lyst. The total amount of naphthalene, tetralin and decalin in the catatyzate, obtained in the transformations of dicyclopentyl on 0.5% Pd/A1203, is 66%

3. Besides isomerization, the Co/A1203 and Ni/AI203 catalysts effect hydrogenolysis of the f ive-membered rings of the dicyclopentyl molecule with the formation of alkyleyclopentanes.

1B

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8.

9,

L I T E R A T U R E C I T E D

N. D. Zelinskii, I. Tits, and L. Fateev, Bet., 59, 2580 (1926). N. I. Shuikin, Uchenye Zapiski Moskov. Gosudar. Univ., 3, 197 (1934). M. B. Turova-Polyak, I. E. Sosnina, and E. G. Treshchova, Zh. Obshch. Khimii, 23, 1111 (1953). N. I. Shuikin, M. I. Cherkashin, and G. K. Gaivoronskaya, Izv. AN SSSR, Otd. Khim. Nauk, 1958, 626. Yu. K. Yur'ev, P,. Ya. Levina, and M. I. Spektor, Zh. Obshch. Khimii, 7, 1581 (1937). M. S. Eventova, Uchenye Zapiski Moskov. Gosudar. Univ., 71, 21 (1941). N. I. Shuikin, M. I. Cherkashin, and I. P. Yakovlev, Izv. AN SSSR, Otd. Khim. Nauk, 1958, 1008. R. Ya. Levina, T. I. Tantsyreva, V. N. Vinogradova, and g. G. Treshchova, Dokl. AN SSSR, 8._.55, 107 (1952). N. I. Shuikin, N. F. Kononov, and L. K. Kashkovskaya, Zh. Obshch. Khimii, 29, 2230 (1959).

All abbreviations of periodicals in the above bibliography are letter-by-letter translitera- tions of the abbreviations as given in the original Russian journal. Some or all o f t h i s per i -

od i ca l l i t e ra ture m a y w e l l be a v a i l a b l e in E n g l i s h t rans la t ion . A complete list of the cover-to- cover English translations appears at the back of this issue.

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