The role of butylbenzene carbenium ions in the acid catalyzed cracking of polystyrene. Transformation of n-butylbenzene, sec-butylbenzene, iso-butylbenzene, tert-butylbenzene, 4-phenyl-1-butene, n-propylbenzene and n-hexylbenzene over silicaalumina and alumina acid catalysts . It is proposed that phenylbutenyl carbenium ion obtained due to dealkylation reaction converts into coke by the successive elimination of H ? and Hions, which in turn take part in hydrogen transfer reactions resulting in the hydrogenation of styrene dimers to diphenylbutane. The dealkylation of this compound leads to active c-butylbenzene carbenium ion which is a key intermediate for the formation of indane and naphthalene derivatives.