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

摘要

The obtained results show that styrene dimers, which are the primary transition products of PS cracking undergo consecutive reactions over acid centers of high acid strength (SiO2-Al2O3(45 %); -10.8 < H-O aecurrency sign -7.9) as well as centers of low acid strength (gamma-Al2O3; H-O > -3.3) at sufficiently high reaction temperatures (723-773 K). It is proposed that phenylbutenyl carbenium ion obtained due to dealkylation reaction converts into coke by the successive elimination of H+ and H- ions, 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 gamma-butylbenzene carbenium ion which is a key intermediate for the formation of indane and naphthalene derivatives.