Various characteristics of supported CoPc ON Al2O3, SiO2 and SiO2-Al2O3 as selective catalysts in the oxidative dehydrogenation of cyclohexene.

Various characteristics of CoPc supported on Al2O3, SiO2 and SiO2-Al2O3 of varying SiO2 mole ratio were investigated. Different pore systems were found to exist depending on the support permitting entrance of CoPc molecules (SiO2 and silica-rich samples) or not (Al2O3 and alumina-rich samples). The major fraction of CoPc appeared as combined with the support surface was much less in silica and silica-rich samples. From chemisorption stoichiometries, CoPc molecules are proposed to lie flat on alumina and alumina-rich surfaces and inclined-edge oriented on silica and silica-rich surfaces. The studied catalysts exhibited good selectivities in the oxidative dehydrogenation of cyclohexene toward benzene. A mechanism was suggested where the formation of an intermediate involving active oxygen species was considered the rate determining step.