MERCAPTAN ADSORPTION CAPACITY AND CATALYTIC-OXIDATION ACTIVITY OF SILICA-SUPPORTED PHTHALOCYANINES

Adsorption capacities of 2-mercaptoethanol at silica-supported phthalocyanatocobalt(II) (CoPc) and (2,9,16,23-tetranitrophthalocyanato)cobalt(II) (CoPc(NO2)4) are determined by a thermal desorption technique. The adsorption capacities correlate with the turnover frequencies for catalytic mercaptan oxidation. The thermal desorption spectra reveal two states of adsorption for thiol as well as for dioxygen at the CoPc(NO2)4-derived sample, but one state only at the CoPc-derived one. Estimated activation energies of desorption depend on the type of phthalocyanine but not on the degree of disperson. The catalytically active sites of a defined supported phthalocyanine are energetically uniform.