Base-catalysed reduction of pyruvic acid in near-critical water

The reduction of pyruvic acid in near-critical water has successfully been conducted under conditions of various temperatures, pressures, reaction time and the presence of formic acid as the reducing agent. In this work, additives (K₂CO₃, KHCO₃, and sodium acetate) used in the reduction of pyruvic acid were also investigated. The results showed that by adding K₂CO₃ (25 mole %) a markedly higher lactic acid yield (70.7 %) was obtained than without additives (31.3 %) at 573.15 K, pressure of 8.59 MPa, 60 min, and in the presence of 2 mol L^?1 formic acid. As a base catalyst, K₂CO₃ definitely accelerated the reduction of pyruvic acid. The reaction rate constants, average apparent activation energy and pre-exponential factor were evaluated in accordance with the Arrhenius equation. The reaction mechanism of the reduction was proposed on the basis of the experimental results.