HOMOGENEOUS AND HETEROGENEOUS CATALYTIC DECOMPOSITION OF HYDROGEN-PEROXIDE BY METALLOPORPHYRIN CARBON-BLACK IN ACID-SOLUTION

The kinetics of hydrogen peroxide decomposition by heat-treated Co-tet ramethoxylphenyl-porphyrin(Co-TMPP)/ carbon black and Fe-tetraphenyl-p orphyrin(Fe-TPP)/carbon black has been studied by a gasometric method in sulphuric acid. In the former case, the reaction order is 1.26 +/- 0.11, indicating that a combined homogeneous and heterogeneous mechani sm is involved. In the latter case, the reaction order is 1.02 +/- 0.1 1, indicating that a heterogeneous mechanism is involved. The nature o f the dissolved species from the heat-treated sample has been studied using UV-visible spectroscopy.