Pedro Yustos

Disproportionation of rosin on an industrial Pd/C catalyst: Reaction pathway and kinetic model discrimination

In this work, a phenomenological study of the isomerisation and disproportionation of rosin acids using an industrial 5% Pd on charcoal catalyst from 200 to 240°C is carried out. Medium composition is determined by elemental microanalysis, GC-MS and GC-FID. Dehydrogenated and hydrogenated acid species molar amounts in the final product show that dehydrogenation is the main reaction. Moreover, both hydrogen and non-hydrogen concentration considering kinetic models are fitted to experimental data using a multivariable non-linear technique. Statistical discrimination among the proposed kinetic models lead to the conclusion hydrogen considering models fit much better to experimental results. The final kinetic model involves first-order isomerisation reactions of neoabietic and palustric acids to abietic acid, first-order dehydrogenation and hydrogenation of this latter acid, and hydrogenation of pimaric acids. Hydrogenation reactions are partial first-order regarding the acid and hydrogen.

Influence of temperature and catalyst loading on the aqueous-phase catalytic oxidation of phenol

Abstract The oxidation of phenol over a copper oxide-copper chromite catalyst has been studied in a basket stirred tank reactor in the temperature range 127-180°C, with a catalyst loading range of 0-120 g/L and using an initial pH of 3.5 and 10. The phenol conversion and its mineralization to carbon dioxide have been measured. A higher oxidation rate of phenol was found when the initial pH was acid. At the lower temperatures studied (127 and 140°C) an increase of both the phenol oxidation rate and the CO 2 /phenol conversion ratio was observed when the catalyst loading was increased. At the highest temperatures used (160 and 180°C) the homogeneous mechanism is the main contribution to the phenol oxidation rate.