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+ under alkaline hydrothermal conditions.

Chemocatalytic Production of Lactates from Biomass-Derived Sugars

“…e hydrothermal process, one of the most potential approaches, is used in the conversion of biomass into valuable resources, since water can serve as a reaction medium bearing special properties when treated in the high temperature and pressure [26]. With respect to the issue of catalytic transformation of biomass into LA with the hydrothermal process using alkaline catalysts, Jin research group made many valuable contributions to this research theme [26][27][28][29][30][31][32][33][34]. Initially, they demonstrated that glycolaldehyde, an aldose with two carbon atoms, usually produced via reverse aldol condensation of C 6 sugars, can also generate LA with 28% yield using 0.75 M·NaOH basic catalyst (300°C, 10 min) [26].…”

Cascade Production of Lactic Acid from Universal Types of Sugars Catalyzed by Lanthanum Triflate

“…In contrast, catalytic processes to produce lactic acid offer high reactionr ates and simple separation of products. [16] Moreover,t he formation of lactic acid salt in alkaline condition makes the separation and purification of lactic acid more difficult. [4,11] This retro-aldol condensation has typicallyb een renderedb ya lkaline conditions, but faces problemso fl ow yield and selectivity for lactic acid with side products including formic acid, malonic acid, and acetic acid.…”

“…[14][15][16] Sels and co-workers reported a6 0% yield of total esters from cellulose catalyzed by tin triflate in methanola t2 00 8Ca fter 4h. [14][15][16] Sels and co-workers reported a6 0% yield of total esters from cellulose catalyzed by tin triflate in methanola t2 00 8Ca fter 4h.…”

“…[4,11] This retro-aldol condensation has typicallyb een renderedb ya lkaline conditions, but faces problemso fl ow yield and selectivity for lactic acid with side products including formic acid, malonic acid, and acetic acid. [16] Moreover,t he formation of lactic acid salt in alkaline condition makes the separation and purification of lactic acid more difficult. It is thus necessary to develop methodst hat can result in high yield and selectivity of lactic acid in neutralc ondition.…”

“…Recently,n on-edible cellulose conversion into lactic acid has become am ajor interesto fm any researchers because it serves as ap latform chemical for the production of varietyo fc hemicals and polymers. [14][15][16] Sels and co-workers reported a6 0% yield of total esters from cellulose catalyzed by tin triflate in methanola t2 00 8Ca fter 4h. [17] Wang et al reported 68 %y ield of lactic acid from ball-milled cellulose catalyzed by Lead (II) ions in aqueous solution at 190 8Ca fter 4h.…”