Glycerol oxidation in liquid phase: Highly stable Pt catalysts supported on ion exchange resins

Abstract

The glycerol oxidation reaction in liquid phase was studied using platinum supported on ion exchange resin as catalysts, with the objective of obtaining glyceric acid. In particular, the effect of the competitor anion, which is the ion used during the support pre-treatment, was addressed. It was found that the competitor ion affects the radial distribution of the active metal in the resin sphere. As the adsorption equilibrium constant of the competitor ion increases, the penetration of platinum in the resin particle also increases. Nevertheless, this difference did not affect the catalytic performance. However, the presence of iodide as competitor ion affected the platinum chemical environment, thus modifying the platinum active sites in this catalyst. Such effect was not observed when chloride or citrate ions were used for the resin pretreatment. Therefore, the competitor ion effect on the platinum catalysts performance is related with the ion nature more than with its affinity for the resin exchange sites. Iodide is adsorbed by platinum, and consequently, it affects its electronic state improving the selectivity. These catalysts showed very good activity, and what is also very important, very good stability, being possible to maintain the conversion and selectivity for many reaction cycles.