Dihydroxyacetone Production: From Glycerol Catalytic Oxidation with Commercial Catalysts to Chromatographic Separation

Review on synthesis of lactic acid and lactates from biomass derived carbohydrates via chemocatalysis routes

The utilization of renewable lignocellulosic biomass resources is a promising solution to deal with the deficit of fossil resources and the associated environmental concerns. Among diverse biomass-derived products, lactic acid (LA) stands out as one of the most successful commodities and also a platform to connect raw biomass feedstocks with value-added chemicals and degradable polymers. Herein, we critically review the recent advances in the design and development of base, acid, and multifunctional catalytic systems for the conversion of different carbohydrates to LA and alkyl lactates via chemical routes. In addition to critically evaluating the advantages and disadvantages of different catalytic systems, we provide deep insights into the reaction mechanisms, including the reaction pathways of different feedstocks, the catalytic roles of different kinds of active sites, and the structure-activity relationship. We conclude with our perspective on the key challenges and future opportunities.

Non-catalytic glycerol dehydrogenation to dihydroxyacetone using needle-in-tube dielectric barrier discharge plasma

Glycerol, a by-product of biodiesel production, could be converted into various value-added products. This work focuses on its dehydrogenation to dihydroxyacetone (DHA), which is mainly used in the cosmetics industry. While several methods have been employed for DHA production, some necessitate catalysts and involve harsh reaction conditions as well as long reaction times. A needle-in-tube type dielectric barrier discharge (DBD) plasma technique for catalyst-free and environmentally-friendly glycerol conversion into DHA via dehydrogenation process was investigated using 0.1 M glycerol dissolved in deionized (DI) water at ambient temperature and pressure. The optimal condition was 60 W input power, 5 mm gap distance between the end of the needle and the liquid surface, and 0.5 L/min He flow rate. The highest DHA yield of 29.3% was obtained at 3 h with a DHA selectivity of 51.6% and glycerol conversion of 56.9%. Although the system allowed over 80% of glycerol to transform after 5 h, the DHA yield decreased after 3 h because the DHA product could further react with the reactive species in the plasma. The catalyst-free DBD plasma technique offers a simple and environmentally conscious method for DHA production via the dehydrogenation of glycerol.

Hydrogenolysis of glycerol over TiO2-supported Pt-WOx catalysts: Effects of the TiO2 crystal phase and WOx loading

The selective hydrogenolysis of glycerol to 1,3-propanediol (1,3-PDO) with high added value is attraction but challenging. Pt-WO_x-based catalysts have been extensively studied in the selective hydrogenolysis of glycerol. The catalyst support and the physicochemical state of WO_x play important roles on this reaction. In this paper, Pt-WO_x catalysts supported on TiO₂ with different crystal forms were prepared and studied for their catalytic performance in hydrogenolysis of glycerol. It was observed that the catalytic performance of anatase-type (A-type) TiO₂-supported catalyst (Pt/W/A-Ti) is much better than that of the rutile-type (R-type) TiO₂ catalyst (Pt/W/R-Ti) due to its higher stability. Furthermore, the influence of W loading amount and state were thoroughly investigated for the Pt/W/A-Ti catalysts, and Pt/W/A-TiO₂ with 5 wt% loading of WO_x achieved the best catalytic performance (100% conversion of glycerol and 41% yield of 1,3-PDO under the optimal reaction conditions), owing to the suitable WO_x domains and high dispersion of W species, as evidenced by XRD patterns and TEM images. Mechanism study by in-situ DRIFTS experiments indicated that glycerol was first converted to 3-hydroxypropanal and then converted to 1,3-PDO through subsequent reactions.