Efficient Catalytic Conversion of Glucose into Lactic Acid over Y-β and Yb-β Zeolites

Valorizing natural-abundant glucose to lactic acid using a MOF-808 catalyst under green hydrothermal conditions

Highly robust Zr-based MOF-808, featuring Lewis acid Zr sites and coordinate hydroxide ions upon the removal of the monocarboxylate capping reagent, emerges as an efficient catalyst for the hydrothermal conversion of glucose into lactic acid. A remarkable 99% glucose conversion with an impressive 76.6% yield of lactic acid can be achieved. The large pore window of MOF-808 facilitates the diffusion of glucose to the active sites within the framework. The single-site attribute of the catalytic center enables a high selectivity of lactic acid over the competitive product, 5-(hydroxymethyl)furfural, under hydrothermal reaction conditions.

Eco-Friendly Approach for the Recovery of Lactic Acid by Complex Extraction

To meet the growing demand for high-purity lactic acid (LA) for biocompatible and biodegradable polymers, LA recovery by green techniques has been attracting the attention. This study focuses on the evaluation of vegetable oils as organic phase diluents in complex extraction of LA with an aliphatic tertiary amine extractant, trioctylamine (TOA). Eight vegetable oils were tested, and their performances were evaluated individually and compared with those obtained using 1-octanol. Extraction yields with these oils were similar; however, efficiencies with safflower oil (SFO) were slightly higher than those obtained with other oils tested. Efficiency with SFO + TOA varied inversely with temperature and pH; however, it increased with higher LA and TOA concentrations. Within the ranges of parameters investigated, the highest yield in SFO was 66% and was achieved at the highest TOA (1.0 M) and LA (1.5 M) concentrations. The efficiency obtained in 1-octanol under the identical conditions was 76%. Thus, the yields obtained with SFO + TOA and 1-octanol + TOA were comparable under most of the conditions tested, especially at the higher LA concentrations, which is preferred for commercial production. Following that, >99% of the LA was transferred from the organic phase to the (second) aqueous phase using NaOH (1.0 M) as a stripping agent. The organic phase was tested in subsequent extractions, and yields comparable to those obtained in the first uses were achieved. This study demonstrated that vegetable oils have the potential to be used as organic phase diluents during complex extraction of LA.