Abstract

Thiophene (C₄H₄S) is among the most important five membered unsaturated heterocyclic compounds along with furan and pyrrole. Thiophenes are usually found in coal tar and petroleum. They are also present in small amounts as impurities in benzene. Because of its poisoning effect to catalysts, the adsorption of thiophene has been studied extensively on various metal, metal sulfide, and metal oxide catalysts.Many different adsorption mechanisms and adsorbed species have been proposed for thiophene on the basis of such studies. The nature of adsorbed species of thiophene appears to be complicated and depends on the nature of the investigated solid, the applied surface treatment, and the conditions under which the adsorption occurs. Little research has been conducted to investigate the adsorption of thiophene on clay minerals. Clay such as montmorillonites can be used as cheap catalysts or adsorbers of impurities. Hidalgo <i>et al.</i> found only physisorption of thiophene on Mg- and Ca-montmorillonites on the basis of their infrared data. Cloos <i>et al.</i> proposed that pi-complex formation occurs between thiophene molecules and Cu-ions when Cu-montmorillonite was treated with thiophene at higher temperatures. This note presents the results of infrared spectra-structure investigation for thiophene adsorbed on <i>H</i>-montmorillonite at room temperature and at higher temperatures where polymerization apparently occurs.

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