Oxidation of limonene over carbon anchored cobalt acetylacetonate catalysts. Effect of the carbon support aging

摘要

The oxidation of limonene with t-butylhydroperoxide, at room temperature and atmospheric pressure, was carried out in the presence of cobalt acetylacetonate [Co(acac)2] anchored on activated carbon, using diamines as linking agents. Different catalysts were prepared by use of diamines of different chain length. The catalyst samples so obtained were characterized by nitrogen adsorption, mass titration and DRIFT. The catalyitc activity of the anchored catalysts was compared to that of a impregnated carbon with Co(acac)2. When fresh catalysts are used, the only reaction product is a polymer, being observed that the type of catalyst has effect over the polymer average molecular weight. Particularly, the lowest molecular weight is obtained with the impregnated catalyst. For the anchored catalysts, the length chain of the diamine used as linking agent has also effect over the polymer average molecular weight, which is higher for the catalyst prepared with hexamethilenediamine. When the oxidation of limonene is carried out with catalyst samples one year aged, the main reaction product is carvone and no polymer is formed.