Phthalocyanines on mineral carriers, 4. Low‐molecular‐weight and polymeric phthalocyanines on SiO₂, γ‐Al₂O₃ and active charcoal as catalysts for the oxidation of 2‐mercaptoethanol

Abstract

Abstract Low‐molecular‐weight phthalocyaninatocobalt compounds 2a – d and polymeric phthalocyaninatocobalt derivatives 4 , 6a , b were prepared on the surface of the inorganic carriers SiO 2 or γ‐Al 2 O 3 and of active charcoal, the range of loading being 11,9 – 0,2 wt.‐%. The oxidation of 2‐mercaptoethanol in an aqueous solution at pH 9 was used as a model reaction for demercaptizations of petroleum fractions with phthalocyanines on carriers as heterogeneous catalysts. The catalytic activity, related to the phthalocyanine content, was found to increase with increasing dispersion of the complex on the carrier. The influence of the type of support on the activity is given by the following order: SiO 2 < γ‐Al 2 O 3 < Norit charcoal. Polymeric phthalocyanines exhibit a higher catalytic activity as compared with low‐molecular‐weight phthalocyanines. The mechanism of the oxidation of the thiol is discussed.