Lactic acid production from aqueous-phase selective oxidation of hydroxyacetone

• Heterogeneous catalytic synthesis of lactic acid from hydroxyacetone.
• Pt-based heterogeneous catalyst has to mandatorily operate under alkaline media.
• Lactic acid synthesis involves hydroxyl oxidation followed by Cannizzaro reaction.

Lactic acid is an important chemical with a wide range of application in food, pharmaceutical and chemical industries. Its worldwide demand has increased due to the ever-growing market of poly(lactic acid) – PLA. This present contribution aims at studying the catalytic transformation of hydroxyacetone toward lactic acid over heterogeneous systems. Commercial Pt/Al2O3 powder catalysts were used and their main features were analyzed as concerning their chemical composition (XRF), crystalline structure (XRD), morphology (TEM) and porosity (N2 physisorption). Catalytic performance was evaluated in aqueous phase and the results showed that the catalytic activity and selectivity to lactic acid depends on the pH of the reaction medium, being mandatory to operate under strong alkaline conditions. Such reaction conditions promote both the initial oxidation of hydroxyacetone and the intramolecular disproportionation of the obtained aldehyde, which are fundamental steps to lactic acid formation. More importantly, this contribution reports the feasibility of alternatively using heterogeneous catalysts to produce lactic acid with high selectivity (>96%).

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