STUDY OF COBALT COMPLEXES AS CATALYSTS IN THE DECOMPOSITION OF HYDROGEN-PEROXIDE

The role of cobalt(II) and its complexes with 1-phenyl 1-hydrazonyl 2- oximinopropanedione (HPHOPD) as homogeneous and heterogeneous catalyst s in the decomposition of hydrogen peroxide has been investigated by m easuring evolution of oxygen at different time intervals in the temper ature range 35-60-degrees-C. Enhanced activity is observed with Co(PHO PD)2 used as heterogeneous catalyst and with cobalt:HPHOPD (1:1) compl ex heterogenized by adsorption on alumina, while in case of solutions of cobalt(II) chloride and cobalt: HPHOPD (1:1), used as homogeneous c atalysts, the activity is comparatively low and negligible respectivel y. The reaction rate, in general, is found to increase with increase i n temperature and quantity of the catalyst. Various thermodynamic para meters have been calculated. The adduct formation with a heterocyclic base like pyridine, 3-methyl pyridine, chloro pyridine or quinoline is found to inhibit the catalytic activity of Co(PHOPD)2. The probable r eaction mechanisms have been suggested for Co(PHOPD)2 and alumina-Co(I I)-HPHOPD as catalysts.