An Acidic Two-Step Hydrothermal Process To Enhance Acetic Acid Production from Carbohydrate Biomass

Catalyst and base-free, direct oxidation of chitin to lactic acid with hydrogen peroxide

In recent years, the research on the conversion of chitin to high value-added chemicals has attracted more and more attention. At present, the method of preparing lactic acid from chitin mostly uses strong base or catalyst. The reaction system under alkaline condition not only corrodes the container but also easily harms the human body. Herein, a simple and effective method to convert chitin to organic acids in catalyst and base-free conditions is developed. The use of H2O2 only can efficiently convert chitin to organic acids in the absence of bases and catalysts. Under the optimal conditions of 30 mg chitin, 2.1 mL water, 0.9 mL H2O2 at 230 °C for 1.5 h, the lactic acid yield of chitin can reach 58.2 % and the total organic acid yield can reach 84.0 %. This work provides an efficient method for the resource utilization of chitin biomass.

Catalytic conversion of cellulosic biomass to harvest high-valued organic acids

Catalytic conversion of biomass provides an alternative way for the production of organic acids from renewable feedstocks. The emerging process contains complex reactions and strategies to cut down those complex biogenic materials into target molecules. Here, we review the catalytic conversion of cellulosic biomass toward high-valued organic acids. This work has summarized the key controlling reactions which lead toward formic acid, glycolic acid, or sugar acids in oxidative conditions and the main pathways for lactic acid or levulinic acid in the anaerobic environment from cellulosic biomass and its derivatives. We evaluate and compare different strategies and methods such as one-pot and two-step conversion. Additionally, the optimization of catalytic reactions has been discussed to realize the design of C-C coupling reactions, the development of multifunctional materials, and new efficient system. In all, this article gives an insight guide to precisely convert cellulosic biomass into target organic acids.

Potential application of carbohydrate biomass in hydrometallurgy: one-pot reduction of metal oxides/salts under mild hydrothermal conditions

Carbohydrate biomass can be employed as a reductant for metallic material preparation due to it possessing diverse reducing functional groups. The reported studies focused on reduction of metal ions in acidic solution with the aid of biomass. However, we found alkali hydrothermal conditions are favorable to metal compound reduction, even direct conversion of metal oxides to metals. Based on our previous research on direct reduction of CuO and NiO into the corresponding metals, herein, conversion of other metal oxides (Fe2O3, MnO2, Co3O4, PbO2) with glucose was investigated to illustrate the universal applicability of direct reduction of metal oxides with carbohydrates under alkali hydrothermal conditions. Furthermore, metal salt reduction by carbohydrates was studied and the reduction performance of glucose and cellulose with and without alkali was compared. The results showed an alkaline hydrothermal environment is more conducive to metal reduction. Unlike the complete reduction of CuO and NiO, oxides of Fe(iii), Mn(iv), Co(iii) and Pb(iv) can only be partially reduced under the experimental conditions. Not only carbohydrates but also decomposed intermediates can reduce metal oxides or salts. In addition, due to the formation of stable complexes between the anions of salts and the decomposition products of carbohydrates, the reduction effects of various copper salts are significantly different. This study may provide an alternative approach to metal preparation in hydrometallurgy.

Degradation process regulation of waste LCD panel to ensure the remain of indium in solid phase by hydrothermal reaction

The environmental risks and recycling potential of organic materials and indium of waste LCD panel has produced commercial value. It has been found that hydrothermal reaction can achieve an efficient and clean degradation of organic materials in a closed environment. However, as the degradation process occurs, the glass substrate is gradually exposed to the hydrothermal environment. Whether the metal indium is dissolved into the liquid phase and whether it affects product quality and the subsequent leaching process need to be discussed. In present study, simultaneous organic materials degradation and pretreatment of indium recycling was achieved due to the regulation of parameters. Effects of reaction temperature, reaction time, H₂O₂ supply and pH of the reaction solution on the transfer of indium in liquid and solid phase were investigated. The results showed that the degradation rate of the organic material reach 90% under the neutral condition of 300℃ of reaction temperature, 36 mL of water and 7.2 mL of H₂O₂ supply and 11 min of reaction time. This pretreatment method effectively realized the resource recovery of waste LCD panel and the outflow of metal indium was inhibited at the same time, thus further comprehensive recycling of resources could be prepared.

Catalytic oxidation of carbohydrates into organic acids and furan chemicals

A review on the development of new routes for the production of organic acids and furan compoundsviacatalytic oxidation reactions.