Chemistry of Heterocyclic Compounds, Vol. 37, No. 5, 2001
CATALYTIC HYDROGENATION
OF THIOPHENE TO THIOLANE
IN THE GAS PHASE
A. V. Mashkina and L. G. Salakhtueva
The hydrogenation of thiophene in the gas phase in the presence of palladium-sulfide catalyst leads to
the production of thiolane and hydrogenolysis products (butane and hydrogen sulfide), which are
formed during the decomposition of the thiophene and thiolane. The hydrogenation rate of thiophene
increases with increase of its content in the reaction mixture and also with increase of the hydrogen
pressure and is reduced by thiolane. The yield of thiolane calculated on the reacted thiophene is
70-90% with 30-60% conversion of the thiophene.
Keywords: thiophene, catalytic hydrogenation.
The selective catalytic reduction of thiophenes to the practically useful thiolanes has been investigated
quite thoroughly in the liquid phase. The most active, selective, and stable catalysts of this process are the
sulfides of metals of group 8 and rhenium [1-3]. In the liquid-phase hydrogenation of thiophene there are
hindrances related to the separation of catalyst and products from the reaction mixture. It was therefore
interesting to develop a method free from this disadvantage for the hydrogenation of thiophenes in the gas phase.
Most publications on the gas-phase hydrogenation of thiophenes as model compounds in the
hydropurification of petroleum products at Mo, W, Ni, and Co catalysts indicate that hydrogenolysis mostly
occurs during the hydrogenation of thiophene with the release of hydrocarbons and hydrogen sulfide and that
thiolane is only formed in small amounts under certain conditions [1, 2, 4, 5]. Nickel-zeolite catalysts are more
active in the production of thiolane, but they are quickly deactivated in the hydrogenation process [6, 7].
In the present work we investigated the relationships governing the hydrogenation of thiophene in the
gas phase in the presence of palladium-sulfide catalyst.
Experiments on the effect of the conditions on the direction of transformation of thiophene and the
hydrogenation rate were conducted at 200-260°C, hydrogen pressure 0.2-3.1 MPa, initial thiophene
) 0.9-4.9 vol. %, and various contact times (τ). In addition to unreacted thiophene, the
concentrations (C0
reaction products contained thiolane, hydrogen sulfide, and butane. Some of the results are presented in Table 1.
As seen, at constant temperature, hydrogen pressure, and initial thiophene concentration the conversion of the
thiophene (X) and yield (Y) of the hydrogenolysis product H2S* increase with increase in the contact time, while
the yield of thiolane calculated on the initial thiophene increases up to a certain limit and then decreases. The
catalyst does not change its initial activity for at least 70 h. (Longer experiments were not undertaken.)
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* Here and subsequently the yield of one of the hydrogenolysis products H2S is given, since in all the
experiments the yields of H2S and butane coincided within the experimental accuracy limits.
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G. K. Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk,
Russia; e-mail: root@catalysis.nsk.su. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5,
pp. 598-601, May, 2001. Original article submitted July 8, 1999.
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0009-3122/01/3705-0546$25.00©2001 Plenum Publishing Corporation