Selective Conversion of Glucose into Lactic Acid with Transition Metal Ions in Diluted Aqueous NaOH Solution

Abstract

An efficient process for the selective conversion of glucose to lactic acid with transition metal ions in diluted aqueous NaOH solution under alkaline hydrothermal conditions was investigated. As a result, Ni2+ was found to be efficient in the production of lactic acid from glucose and decreased simultaneously the NaOH concentration. The highest yield of 25% for lactic acid was achieved with 0.01 M Ni2+, 0.01 M NaOH, and 35% water filling at 300 °C for 1 min. In addition, our results suggest that the role of Ni2+ acts as not only as a catalyst but also as an oxidant for the conversion of glucose into lactic acid and differs from CuO as an oxidant in the conversion of cellulose or glucose into carboxylic acids in previous works. Also, the NaOH concentration in this process is remarkably reduced and gives almost the same yield compared to 2.5 M NaOH as reported previously. The mechanistic studies for lactic acid formation from glucose showed that the glyceraldehyde might act as an intermediate with Ni2+ und...