Abstract:

 The novel bifunctional catalysts for mercaptan autoxidation have been prepared by supporting a mixture of cobalt phthalocyanine tetrasodium sulphonate CoPc(SO3Na) 4 (CPTS) and Cobalt phthalocyanine tetra(trimethylammonium) iodide CoPc[N(CH 3) 3I] 4 (CPTI) on mixed MgAl oxide ( Mg(A1)O ) derived from thermal decomposition of Mg Al hydrotalcite. The resulting catalysts were examined by the autoxidation reaction of 1-octanethiol. The catalyst shows an increase in reaction rate for the 1-octanethiol autoxidation as compared with an equal amount of catalyst containing CPTS or CPTI alone, and the highest activitiy and stability was achieved when the catalyst containing equimolar amount of CPTS and CPTI was used. This is the result of the matching of positive charge of CPTI and negative charge of CPTS, which prevents the aggregation of Co 2+ centers and the formation of less active peroxo complex: -Co(Ⅲ)-O-O-Co(Ⅲ) to a certain degree. The autoxidation reaction catalyzed by these bifunctional catalysts follows two substrate Michaelis Menten kinetics with respect to both of 1-octanethiol and oxygen and the apparent activation energy is 50.4 kJ•mol -1 .
 

Key words: Hydrotalcite, Solid base, Cobaltphthalocyanines, Autoxidation of mercaptans, Bifunctional catalyst